Liquid discharge device and liquid discharge head

Abstract

To provide a technique which can eliminate sedimentation of a containing material generated in a circulation path while achieving stable circulation of liquid.SOLUTION: Circulation control means can execute: first circulation which returns liquid from a first pressure control chamber to the first pressure control chamber through discharge means for discharging the liquid and a second pressure control chamber using a pressure difference in the first pressure control chamber and the second pressure control chamber; and second circulation which recovers the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means to supply means which can supply the liquid to the first pressure control chamber without controlling the first pressure control chamber and the second pressure control chamber by each corresponding negative pressure while supplying the liquid to the first pressure control chamber.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and a liquid ejection head. [Background technology]

[0002] In recent years, the applications of liquid ejection devices that eject liquid are becoming more diverse, including recording devices that eject ink to record, and modeling devices for forming electrodes and manufacturing biochips, etc. For this reason, liquid ejection devices are required to stably eject various types of liquid, such as liquids that contain high concentrations of materials and liquids that contain materials with high specific gravity.

[0003] Patent Document 1 discloses a technique for discharging air bubbles in ink and eliminating settling of pigments dispersed in ink. The technique disclosed in Patent Document 1 includes a main circulation path capable of supplying ink from a common liquid chamber to a pressure chamber communicating with an ejection port, and sub-circulation paths for flowing ink from one side of the extension direction of the common liquid chamber to the other side, on either side of the ink inflow position into the common liquid chamber in the main circulation path. By switching between the two types of circulation paths, discharging air bubbles and eliminating settling are achieved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-121416 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology disclosed in Patent Document 1, if a pressure regulator with a pressure adjustment function is used in order to stably circulate the ink at a constant pressure in the main circulation path, it becomes difficult to control the ink flow rate to temporarily increase. For this reason, it is possible to use a sub-circulation path, but in this case, it is not possible to eliminate sedimentation that occurs in parts of the main circulation path other than the common liquid chamber shared with the sub-circulation path.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology that can eliminate the settling of contained materials that occurs within the circulation path while realizing stable liquid circulation. [Means for solving the problem]

[0007] In order to achieve the above object, one embodiment of a liquid ejection device according to the present disclosure includes a first pressure control chamber controlled to a first negative pressure, a second pressure control chamber connected to the first pressure control chamber via a flow path and controlled to a second negative pressure lower than the first negative pressure, ejection means capable of ejecting liquid supplied from the first pressure control chamber from an ejection port and recovering liquid not ejected from the ejection port in the second pressure control chamber, supply means capable of supplying stored liquid to the first pressure control chamber and recovering liquid in the first pressure control chamber, the second pressure control chamber, and the ejection means, and a control unit for controlling the first pressure control chamber, the second pressure control chamber, and the ejection means. and a circulation control means capable of controlling the circulation of liquid among the first pressure control chamber, the discharge means, and the supply means, wherein the circulation control means is capable of performing a first circulation in which liquid is returned to the first pressure control chamber from the first pressure control chamber through the discharge means and the second pressure control chamber by utilizing a pressure difference between the first pressure control chamber and the second pressure control chamber, and a second circulation in which liquid is supplied to the first pressure control chamber, while the first pressure control chamber and the second pressure control chamber are not controlled to their corresponding negative pressures, and the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means is recovered to the supply means. Effect of the Invention

[0008] According to the present invention, it is possible to realize stable circulation of liquid while eliminating settling of contained materials that occurs within the circulation path. [Brief description of the drawings]

[0009] [Figure 1] Schematic diagram of a recording device [Diagram 2] External view of the recording head [Diagram 3] Exploded view of the recording head [Figure 4] Cross-sectional view of the recording element substrate [Diagram 5] Circulation unit schematic diagram [Figure 6] Exploded view of the circulation unit [Figure 7] Perspective view of the circulation unit [Figure 8] Diagram showing the flow of ink in the circulation unit [Figure 9] FIG. 1 is a diagram showing an ink circulation path in a recording apparatus; [Figure 10] A block diagram showing the configuration of a control system of a printing apparatus. [Figure 11] Diagram explaining the second circulation [Figure 12] FIG. 13 is a diagram showing an ink circulation path in a recording apparatus according to another embodiment; [Figure 13] FIG. 10 is a diagram illustrating a second circulation in another embodiment. [Figure 14] FIG. 1 is a diagram showing the flow of ink in the vicinity of each pressure control chamber and each pressure control mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a liquid ejection device and a liquid ejection head will be described with reference to the accompanying drawings. Note that the following embodiment does not limit the present invention, and not all of the combinations of features described in the present embodiment are essential to the solution of the present invention. Furthermore, the positions and shapes of the components described in the embodiment are merely examples, and are not intended to limit the present invention to only those.

[0011] (First embodiment) First, a liquid ejection device according to a first embodiment will be described with reference to Figs. 1 to 11. In this embodiment, a recording device that ejects ink to a recording medium by an inkjet method and records will be described as an example of a liquid ejection device. Therefore, in this embodiment, a liquid ejection head will be described as a recording head. Recording devices include devices such as copying machines, facsimiles with communication systems, and word processors with recording functions, as well as industrial recording devices that are combined with various processing devices. In addition, the liquid ejection device according to the present invention can also be used for applications such as the production of biochips, printing of electronic circuits, and printing on non-absorbent media.

[0012] <Recording device configuration> FIG. 1 is a schematic diagram of a recording device. The recording device 10 in FIG. 1 includes a carriage 14 movably mounted on a guide shaft 12 extending in the X direction (predetermined direction), and a recording head (liquid ejection head) 16 mounted on the carriage 14 and capable of ejecting ink as a liquid by an inkjet method. Therefore, in the recording device 10, the recording head 16 is movable in the X direction via the carriage 14. In the recording device 10, when the recording medium M is conveyed by a conveying unit (not shown) in a Y direction intersecting the X direction (orthogonal in this embodiment) and reaches a recording start position, a recording operation is performed in which ink is ejected from the recording head 16 moving in the X direction onto the recording medium M. Thereafter, a conveying operation is performed in which the conveying unit conveys the recording medium M by a predetermined amount, and then the recording operation is performed again. In this manner, in the recording device 10, recording is performed by alternately executing a recording operation and a conveying operation.

[0013] The recording head 16 is composed of two types of recording heads, namely, the recording head 16a capable of ejecting six types of ink, and the recording head 16b capable of ejecting three types of ink. That is, in this embodiment, the recording head 16 is configured to be capable of ejecting nine types of ink. The recording head 16 may be configured to be composed of one type of recording head, or may be configured to be composed of three or more types of recording heads. In addition, the types of ink that the recording heads 16a and 16b can eject are not limited to the above number. Furthermore, the recording head 16 is not limited to ejecting only ink, and may be configured to be capable of ejecting liquid such as a processing liquid that performs a predetermined process on the ejected ink.

[0014] The recording device 10 includes an ink supply unit 20 capable of supplying ink stored in an ink tank 18 to the recording head 16. The ink tanks 18 store different types of ink to be ejected from the recording head 16, each independently, and in this embodiment, nine types of ink are stored. The ink tanks 18 provided in the ink supply unit 20 are connected to the recording heads 16a and 16b via a supply tube 22. The ink supply unit 20 includes a pump 904 (see FIG. 9), which pressurizes and supplies ink from the ink tanks 18 to the recording head 16 via the supply tube 22.

[0015] Although details will be described later, in this embodiment, the recording head 16b is configured to eject white ink containing a material (pigment) with a large specific gravity, and a recovery tube 24 for recovering the white ink from the recording head 16b is connected to the recording head 16b. One end of the recovery tube 24 is connected to the recording head 16b, and the other end is connected to a tank that stores the white ink in the ink tank 18. In this embodiment, the recovery tube 24 is provided at one location on the recording head 16b, but this is not limited to this. In other words, when the recording heads 16a and 16b eject a plurality of inks containing a material with a large specific gravity, that is, inks in which sedimentation of the contained material is likely to occur, recovery tubes 24 are provided in the number corresponding to the inks.

[0016] <Recording head configuration> Next, the configuration of the recording head 16 will be described. In this embodiment, the recording head 16b ejects ink in which sedimentation of contained materials is likely to occur. In this specification, "ink in which sedimentation of contained materials is likely to occur" is simply referred to as "ink in which sedimentation is likely to occur" as appropriate. Since the recording head 16a that is not configured to eject ink in which sedimentation is likely to occur can use known technology, the detailed description of the configuration will be omitted in the following description. In other words, the configuration of the recording head 16b to which the recovery tube 24 is connected will be described in detail in the following description.

[0017] Fig. 2 is an external view of the recording head 16b. Fig. 3 is an exploded view of the recording head 16b. The recording head 16b includes a recording element unit 304 having a recording element substrate 302, a circulation unit 306 that circulates ink to be supplied to the recording element substrate 302, and a housing unit 308 and a cover 310 that cover the circulation unit 306 (see Fig. 3). The recording head 16b is fixedly supported by the carriage 14 by a positioning portion (not shown) and an electrical contact provided on the carriage 14.

[0018] =Recording element unit 304= The recording element unit 304 includes a recording element substrate 302 capable of ejecting ink to be supplied, and a support member 312 (see FIG. 3) on which connection flow paths 916, 918 (see FIG. 9) are formed, which connect flow paths formed in the circulation unit 306 and the recording element substrate 302. The recording element unit 304 also includes an electric contact substrate 314 connected to an electric contact provided on the carriage 14, and an electric wiring tape 316 connecting the electric contact substrate 314 and the recording element substrate 302.

[0019] The electrical contact board 314 is configured to be electrically connectable to the electrical contacts of the carriage 14, and supplies a drive signal and drive energy to a circulation pump 322 mounted on the circulation unit 306 via a circulation unit connector 318 and a pump wiring (not shown). The electrical contact board 314 also supplies a drive signal and drive energy for driving the ejection energy generating elements 412 (see FIG. 4), which are recording elements, to the recording element board 302 via the electrical wiring tape 316. An anisotropic conductive film, wire bonding, solder mounting, etc. are used for the electrical connection between the recording element board 302 and the electrical wiring tape 316, but the method of electrically connecting the recording element board 302 and the electrical wiring tape 316 is not limited to this. In this embodiment, the connection between the recording element board 302 and the electrical wiring tape 316 is performed by wire bonding, and the part electrically connected by wire bonding is sealed with a sealant.

[0020] The recording element unit 304 is adhesively fixed to the housing unit 308, whereby the flow path of the circulation unit 306 fixed to the housing unit 308 communicates with the flow path of the recording element substrate 302 via connection flow paths 916, 918 formed in the support member 312. The recording element unit 304 and the housing unit 308 may be connected via an elastic member such as rubber or elastomer as a sealing member. The housing unit 308 is configured by combining parts that are injection molded from resin containing filler, since it has an engagement portion (not shown) for a positioning portion of the carriage 14 and an ink flow path formed therein.

[0021] =Circulation Unit 306= The recording head 16b is configured to be capable of ejecting three types of ink including ink that is prone to settling. In this embodiment, the recording head 16b is configured to be capable of ejecting white ink, which is ink that is prone to settling, and light magenta ink and light cyan ink, which are inks that are not prone to settling, i.e., inks that are relatively less prone to settling. The circulation unit 306a corresponds to the white ink, and the circulation unit 306b corresponds to the light magenta ink and light cyan ink. That is, the white ink supplied from the supply tube 22 is sent to the recording element unit 304 via the circulation unit 306a. Also, the light magenta ink and light cyan ink supplied from the supply tube 22 are sent to the recording element unit 304 via the circulation unit 306b.

[0022] The circulation units 306a and 306b include a first pressure control mechanism 320, a second pressure control mechanism 500 (see FIG. 5), and a circulation pump 322. The configurations of the first pressure control mechanism 320, the second pressure control mechanism 500, and the circulation pump 322 will be described later. The circulation units 306a and 306b include a supply port 324 for allowing ink to flow into the inside. Here, the housing unit 308 to which the supply tube 22 is connected at the connection portion 326 includes a flow path 912 (see FIG. 9) connected to the supply port 324 of the fixed circulation units 306a and 306b. As a result, the ink supplied from the supply tube 22 flows through the flow path 912 to the supply port 324.

[0023] The circulation units 306a and 306b are provided with a recovery port 328 for allowing ink to flow out from the inside. Here, the housing unit 308 to which the recovery tube 24 is connected at the connection portion 330 is provided with a flow path 922 (see FIG. 9) connected to the recovery port 328 of the fixed circulation units 306a and 306b. This allows the ink flowing out from the recovery port 328 to flow through the flow path 922 to the recovery tube 24. Note that the recovery port 328 is connected to the flow path 922 in the circulation unit 306a corresponding to the white ink that is prone to settling, but is not connected to the flow path 922 in the circulation unit 306b corresponding to the light magenta ink and light cyan ink that are less likely to settling. Therefore, in this embodiment, the recovery tube 24 is connected only to the connection portion 330 corresponding to the flow path 922 that is connected to the recovery port 328 of the circulation unit 306a.

[0024] The circulation units 306a and 306b are fixed to the housing unit 308 by screws 332. As a result, the supply port 324 and the flow path 912 are connected and communicated, and the recovery port 328 and the flow path 922 are connected. However, in the circulation unit 306b, the recovery port 328 and the flow path 922 are not connected, and only in the circulation unit 306a, the recovery port 328 communicates with the flow path 922. An elastic material such as rubber or elastomer is used as a seal member provided at the connection portion. Since the recording head 16b is configured as described above, the recording head 16b is configured to be able to easily deal with the tendency of the contained material of the ejected ink to settle by changing the circulation units 306a and 306b. At this time, the communication state between the recovery port 328 and the flow path 922 and the connection to the connection part 330 of the recovery tube 24 are changed according to the change between the circulation units 306a and 306b.

[0025] <Configuration of the Printing Element Substrate 302> Next, the configuration of the recording element substrate 302 will be described. FIG. 4 is a cross-sectional view of the recording element substrate 302. The recording element substrate 302 includes a substrate 402, an ejection port forming member 404 covering one surface of the substrate 402, and a cover plate 406 covering the other surface of the substrate 402. The ejection port forming member 404 is formed with a pressure chamber 408 that stores ink to which ejection energy is applied, and an ejection port 410 through which the ink in the pressure chamber 408 is ejected to the outside by the applied ejection energy. In the ejection port forming member 404, a plurality of ejection ports 410 are arranged along the extending direction of the recording element substrate 302. In the pressure chamber 408, an ejection energy generating element 412 that generates ejection energy as a recording element is provided at a position facing the ejection port 410 on the substrate 402. As the ejection energy generating element 412, a known element such as an electrothermal conversion element or a piezoelectric element can be used.

[0026] When an electrothermal conversion element is used, the heat generated by the element causes the ink in the pressure chamber 408 to bubble, and the resulting bubble-forming energy is used to eject ink from an ejection port 410 communicating with the pressure chamber 408. The pressure chamber 408 is formed with an inlet 414 for allowing ink to flow into the pressure chamber 408 on one side in a direction intersecting the arrangement direction of the ejection ports 410, and an outlet 416 for allowing ink to flow out of the pressure chamber 408 on the other side in the same direction. Each of the inlet 414 and the outlet 416 is provided for one or more ejection ports 410.

[0027] A supply channel 418 and a recovery channel 420 are formed in the substrate 402, extending parallel to each other along the extension direction of the discharge port 410. An inlet 414 is connected to the supply channel 418, and an outlet 416 is connected to the recovery channel 420. The supply channel 418 and the recovery channel 420 are open on the other surface side of the substrate 402, and the openings are covered by a cover plate 406.

[0028] The cover plate 406 is formed with an opening 422 that connects the supply flow channel 418 and the recovery flow channel 420 to the outside. The supply flow channel 418 is connected, via the opening 422, to a connection flow channel 916 (see FIG. 9) that communicates with a first air bubble storage flow channel 914 (see FIG. 9) described later. The recovery flow channel 420 is connected, via the opening 422, to a connection flow channel 918 (see FIG. 9) that communicates with a second air bubble storage flow channel 920 (see FIG. 9) described later. The first air bubble storage flow channel 914 and the second air bubble storage flow channel 920 are provided in the support member 312.

[0029] The openings connecting the supply flow passage 418 to the outside and the openings connecting the recovery flow passage 420 to the outside may each be provided in a single number, or two or more openings may be provided. The openings connecting the supply flow passage 418 to the outside and the openings connecting the recovery flow passage 420 to the outside may each be provided in the same number, or one may be provided more than the other. For example, nine openings 422 are formed in one supply flow passage 418, and eight openings 422 are formed in one recovery flow passage 420.

[0030] The cover plate 406 is preferably made of a material that has sufficient corrosion resistance against the ink discharged from the discharge port 410. In addition, from the viewpoint of preventing color mixing, high precision is required for the shape and position of the opening 422. For this reason, it is preferable to use a photosensitive resin material or a silicon plate as the material for the cover plate 406, and form the opening 422 by a photolithography process.

[0031] =Flow path in the recording element substrate 302= In the recording element substrate 302, ink supplied from the connection flow path 916 to the supply flow path 418 through the opening 422 flows into the pressure chamber 408 through the inlet 414 (see arrow I in FIG. 4). The ink that flows into the pressure chamber 408 flows out through the outlet 416 to the recovery flow path 420 (see arrow II in FIG. 4), and the ink in the recovery flow path 420 is recovered to the connection flow path 918 through the opening 422. The connection flow path 916 is connected to the first pressure control chamber 508 (see FIG. 5) that is pressure-controlled to a relatively low negative pressure through the first air bubble storage flow path 914 (see FIG. 9). The connection flow path 918 is connected to the second pressure control chamber 528 (see FIG. 5) that is pressure-controlled to a relatively high negative pressure through the second air bubble storage flow path 920 (see FIG. 9). The first pressure control chamber 508 and the second pressure control chamber 528 will be described later.

[0032] Therefore, the supply flow path 418 connected to the connection flow path 916 has a higher pressure than the recovery flow path 420 connected to the connection flow path 918, and this pressure difference causes ink to flow in the directions of arrows I and II in FIG. 4 in each pressure chamber 408. This ink flow makes it possible to, for example, recover ink that has thickened in the ejection port 410 during non-printing operation, and to suppress the increase in ink viscosity in the ejection port 410 that does not eject ink during printing operation. This makes it possible to suppress the deterioration of the ink ejection performance in each ejection port 410. In this way, in this embodiment, the recording element substrate 302 functions as an ejection section that can eject the supplied liquid through the ejection port and recovers the liquid that has not been ejected from the ejection port.

[0033] <Configuration of circulation unit 306> Next, the configuration of the circulation unit 306a will be described. Fig. 5 is a schematic diagram of the circulation unit 306a. Fig. 6 is an exploded view of the circulation unit 306a. Fig. 7 is a perspective view of the circulation unit 306a. The configuration of the circulation unit 306b differs from that of the circulation unit 306a only in that the recovery port 328 of the circulation unit 306a does not communicate with the flow path 922 that communicates with the connection part 330 to which the recovery tube 24 is connected.

[0034] The first pressure control mechanism 320 provided in the circulation unit 306a includes a first pressure control valve 502, a valve spring 504, and a spring receiver 506 (see FIG. 5), and these components are provided on one surface side of the base 600 (see FIG. 6). The first pressure control mechanism 320 also includes a first pressure receiving plate 510 disposed in the first pressure control chamber 508, and a first control spring 512 that biases the first pressure control chamber in a direction to expand the volume of the first pressure control chamber via the first pressure receiving plate 510 (see FIG. 5). These components are provided on the other surface side of the base 600 (see FIG. 6). The first pressure control mechanism 320 also includes a film 514 that covers the other surface side of the base 600 and constitutes a part of the multiple flow paths and a variable membrane in the first pressure control mechanism 320 (see FIG. 6).

[0035] The second pressure control mechanism 500 provided in the circulation unit 306a includes a second pressure control valve 522, a valve spring 524, and a spring receiver 526 (see FIG. 5), and these components are provided on the other surface side of the base 600 (see FIG. 6). The second pressure control mechanism 500 also includes a second pressure receiving plate 530 disposed in the second pressure control chamber 528, and a second control spring 532 that biases the second pressure control chamber 528 in a direction to expand the volume of the second pressure control chamber 528 via the second pressure receiving plate 530 (see FIG. 5). These components are provided on one surface side of the base 600 (see FIG. 6). The second pressure control mechanism 500 also includes a film 534 that covers one surface side of the base 600 and constitutes a part of the multiple flow paths and a variable membrane in the second pressure control mechanism 500.

[0036] As described above, in this embodiment, the first pressure control mechanism 320 and the second pressure control mechanism 500 are of a linear motion type using a wire spring, but are not limited to this. The first pressure control mechanism 320 and the second pressure control mechanism 500 may be a control mechanism including a leaf spring or a rotational motion, or may be configured as a pressure control mechanism controlled externally.

[0037] The circulation unit 306a includes a filter 540 in addition to the first pressure control mechanism 320, the second pressure control mechanism 500, and the circulation pump 322. The ink flowing in from the flow path 912 flows through the filter 540 and the first pressure control mechanism 320 into the first pressure control chamber 508, the internal negative pressure of which is controlled by the first pressure control mechanism 320. The first pressure control chamber 508 is connected to the second pressure control chamber 528 by two flow paths 542 and 544, and the circulation pump 322 is provided in the flow path 544. In addition, a recovery flow path 924 (see FIG. 9) is connected to the flow path 544 between the second pressure control chamber 528 and the circulation pump 322, and extends to the recovery port 328.

[0038] The circulation pump 322 is a diaphragm pump, and includes two check valves 543, a pump connection part 644 (see FIG. 6) that fixes the check valves 543 to the base part 600, a piezoelectric element 526 that serves as a driving element, and a pump housing 527 whose volume can be changed by the piezoelectric element 526. Of the two check valves 543, one check valve 543a is provided so as to be able to suck ink from the second pressure control chamber 528 side, and the other check valve 543b is provided so as to be able to discharge ink to the first pressure control chamber 508 side. With this configuration, by applying a driving voltage to the piezoelectric element 526, the volume inside the pump housing 527 (see FIG. 5) is changed, and the two check valves move alternately due to pressure fluctuations, making it possible to transport ink from the second pressure control chamber 528 to the first pressure control chamber 508. The circulation pump 322 is capable of changing the pump capacity by the voltage and frequency applied to the piezoelectric element 526.

[0039] In the recording device 10, an ink circulation path (described later) including a flow path provided in the circulation unit 306a is provided in the recording head 16b, thereby making the circulation path smaller and requiring less pumping power to stably eject ink from the ejection openings 410. This makes it possible to reduce the size of the circulation pump 322, thereby making it possible to reduce the size of the recording head 16 and accommodate high-speed recording.

[0040] In the recording apparatus 10, the first pressure control mechanism 320 and the second pressure control mechanism 500 function to maintain a constant pressure difference between the first pressure control chamber 508 and the second pressure control chamber 528. This makes it possible for the recording apparatus 10 to stably eject ink while circulating the ink in a circulation path including the circulation unit 306a and the flow path in the recording element substrate 302. This makes it possible to suppress, for example, thickening of ink in the ejection ports 410 that do not eject ink during a recording operation.

[0041] The second pressure control mechanism 500 is capable of generating a negative pressure in the second pressure control chamber 528 by applying a reaction force of the second control spring 532 to the film 534 via the second pressure receiving plate 530. Moreover, the second pressure control mechanism 500 is capable of adjusting the valve opening pressure of the second pressure control valve 522 by adjusting the spring constant of the second control spring 532, the spring constant of the valve spring 524, and the set pressure of the first pressure control chamber 508.

[0042] When the ink in the second pressure control chamber 528 is collected by the circulation pump 322 and the pressure in the second pressure control chamber 528 falls below the valve opening pressure of the second pressure control valve 522, the second pressure control valve 522 opens the orifice 546. This causes ink to flow from the first pressure control chamber 508 to the second pressure control chamber 528 via the flow path 542. When the pressure in the second pressure control chamber 528 exceeds the valve opening pressure of the second pressure control valve 522 due to the inflow of ink from the first pressure control chamber 508 via the flow path 542, the second pressure control valve 522 closes the orifice 546, and the second pressure control chamber 528 returns to the set negative pressure.

[0043] By this operation, even if the amount of ink circulating between the circulation unit 306a and the recording element substrate 302 connected via the connection flow path 918 or the like changes, the negative pressure in the second pressure control chamber 528 can be maintained at the set negative pressure.

[0044] The first pressure control mechanism 320 is capable of generating a negative pressure in the first pressure control chamber 508 by applying a reaction force of the first control spring 512 to the film 514 via the first pressure receiving plate 510. The first pressure control mechanism 320 is also capable of adjusting the valve opening pressure of the first pressure control valve 502 by adjusting the spring constant of the first control spring 512, the spring constant of the valve spring 504, and the pressure at which ink is supplied to the first pressure control chamber 508. The pressure at which ink is supplied to the first pressure control chamber 508 is a pressure that takes into consideration the pressure of the pump 904 applied to the flow path that guides the ink flowing out from the filter 540 to the first pressure control mechanism 320, and the pressure loss due to the flow of ink in the supply tube 22 and the filter 540.

[0045] When ink flows out from the first pressure control chamber 508 to the second pressure control chamber 528 via the flow path 542 and the pressure in the first pressure control chamber 508 falls below the valve opening pressure of the first pressure control valve 502, the first pressure control valve 502 opens the orifice 548. This causes ink supplied via the filter 540 to flow into the first pressure control chamber 508. Then, when the pressure in the first pressure control chamber 508 exceeds the valve opening pressure of the first pressure control valve 502 due to the inflow of ink into the first pressure control chamber 508, the first pressure control valve 502 closes the orifice 548 and the first pressure control chamber 508 returns to the set negative pressure.

[0046] When ink is ejected from the ejection port 410, the amount of ink in the circulation path including the flow path in the recording element substrate 302 and the circulation unit 306a decreases, and the negative pressure in the entire circulation path increases (i.e., the pressure decreases). The amount of ink collected by the second pressure control mechanism 500 varies depending on the pressure difference between the first pressure control chamber 508 and the second pressure control chamber 528, so the second pressure control mechanism 500 does not contribute to pressure control in the circulation path. Therefore, the first pressure control mechanism 320 adjusts the pressure in the circulation path by allowing ink supplied through the filter 540 to flow in to replace the ink ejected from the ejection port 410, so that ink can be ejected from the ejection port 410 stably.

[0047] A seal member 702 is disposed at the connection between the circulation unit 306a and the flow paths 912 and 922 provided in the housing unit 308 (see FIG. 7). A seal member 704 is disposed at the connection between the circulation unit 306a and the first air bubble storage flow path 914 and the second air bubble storage flow path 920 (see FIG. 7). These seal members 702 and 704 are joined by two-color molding of elastomer. The seal members 702 and 704 may be made of a rubber material such as EPDM.

[0048] <Ink flow in circulation unit 306a> Next, the flow of ink in the circulation unit 306a will be described. The flow of ink in the circulation unit 306a described here is the flow of ink in the first circulation described later. FIG. 8 is a diagram for explaining the flow of ink in the circulation unit 306a, where (a) shows one side of the base 600 and (b) shows the other side of the base 600. In the circulation unit 306a, grooves formed on one side and the other side of the base 600 and films 514 and 534 form a flow path through which the ink circulates. Parts that receive spring reaction force and the like are reinforced with members such as the first pressure receiving plate 510 and the second pressure receiving plate 530 and the spring receivers 506 and 526.

[0049] In the recording device 10, the ink circulation mechanism is made compact by mounting the circulation unit 306a, which includes the circulation pump 322, the first pressure control mechanism 320, and the second pressure control mechanism 500, on the recording head 16b. This makes it possible to stably eject ink while suppressing ink viscosity increase even in large-scale devices such as large-format printers.

[0050] In order to reduce the size, the circulation unit 306a penetrates the base 600 and connects the flow paths formed on one side and the other side of the base 600. Specifically, the ink flowing in from the supply port 324 passes through the filter 540 provided on one side of the base 600 and flows out to the other side of the base 600 through the through hole 802. After that, the ink flowing in through the through hole 802 to the flow path provided on the other side flows out to the one side through the through hole 804 (see arrow A), and then flows out to the other side through the orifice 548 (see arrow B). The ink flowing in to the other side through the orifice 548 flows out of the circulation unit 306a through the outflow port 706 (see FIG. 7) (see arrow C) and flows into the first bubble storage flow path 914. Furthermore, ink that has flowed through orifice 548 to the other surface flows out through through hole 806 to one surface (see arrow D), and then flows out through through hole 808 to the other surface.

[0051] Ink that flows into the other surface side through the through hole 808 flows out through the orifice 546 to the one surface side (see arrow E). In addition, on the other surface, ink that flows in from the second bubble storage channel 920 through the inlet 708 (see FIG. 7) (see arrow F) flows out to the one surface side through the through hole 810 and merges with the ink that flows out to the one surface side through the orifice 546. The merged ink then flows out to the other surface side through the through hole 812 (see arrow G), and then flows out to the outside of the circulation unit 306a from the recovery port 328 (see the dashed arrow), and flows out to the one surface side through the through hole 814 (see arrow H). Ink that flows into one side through through hole 814 flows out to the other side through through hole 816 in which one check valve 543a is provided (see arrow J), and then flows out to the one side through through hole 818 in which the other check valve 543b is provided (see arrow K).

[0052] The filter 540 traps and collects foreign matter contained in the ink flowing in from the supply port 324, thereby preventing blockage of the flow paths provided in the circulation unit 306a and the recording element substrate 302. Check valves 543a and 543b are disposed on the other side of the through holes 816 and 818 via the pump connection portion 644. As the pressure adjustment function of the first pressure control mechanism 320 and the second pressure control mechanism 500, the stability of the valve opening and closing of the pressure control valves 502 and 522 and the stable ink recovery function of the orifices 546 and 548 are important.

[0053] <Ink circulation path> Next, we will explain the ink circulation path in the recording device 10. Fig. 9 is a diagram explaining the ink circulation path provided in the recording device 10. In the recording device 10, the ink supply unit 20 and the recording head 16b are connected by a supply tube 22 and a recovery tube 24, forming a circulation path that can circulate ink between the ink supply unit 20 and the recording head 16b.

[0054] In the ink supply unit 20, the ink tank 18 is connected to the supply tube 22 via a supply path 902. The supply path 902 is provided with a pump 904 capable of transferring ink stored in the ink tank 18 to the supply tube 22. In addition, the supply path 902 is provided with a supply valve 906 that can be opened and closed between the pump 904 and the ink tank 18. When the supply valve 906 is in an open state, the ink stored in the ink tank 18 can be transferred to the supply tube 22 via the supply path 902 by driving the pump 904. On the other hand, when the supply valve 906 is in a closed state, the ink stored in the ink tank 18 cannot be transferred to the supply tube 22 via the supply path 902 even if the pump 904 is driven. In this way, in the ink supply unit 20, the supply valve 906 is configured to permit and restrict the transfer of ink from the ink tank 18 to the supply tube 22.

[0055] The ink supply unit 20 also includes a recovery path 908 that guides the ink flowing in through the recovery tube 24 to the supply path 902. The recovery path 908 is connected to the supply path 902 between the pump 904 and the supply valve 906. The recovery path 908 is also provided with a recovery valve 910, and when the recovery valve 910 is in an open state, the ink flowing in to the recovery path 908 can be guided to the supply path 902, and when the recovery valve 910 is in a closed state, the ink cannot be guided to the supply path 902 through the recovery path 908. In this way, the ink supply unit 20 is configured such that the recovery valve 910 allows and restricts the inflow of ink through the recovery tube 24 and the like.

[0056] The ink supplied through the supply tube 22 flows into the circulation unit 306a through a flow path 912 provided in the housing unit 308, and then flows into the first pressure control chamber 508 equipped with the first pressure control mechanism 320 through the filter 540. The ink that flows into the first pressure control chamber 508 flows into the second pressure control chamber 528 equipped with the second pressure control mechanism 500 through the flow path 542. The ink that flows into the first pressure control chamber 508 flows into the recording element substrate 302 through the outlet 706, the first bubble storage flow path 914, and the connection flow path 916. In the recording element substrate 302, the ink flows out from the opening 422 to the connection flow path 918 through the supply flow path 418, the inlet 414, the pressure chamber 408, the outlet 416, and the recovery flow path 420.

[0057] The ink that has flowed into the connection flow path 918 flows through the second bubble storage flow path 920, into the circulation unit 306a from the inlet 708, and into the second pressure control chamber 528. The ink in the second pressure control chamber 528 can flow into the first pressure control chamber 508 through the flow path 544. In addition, the flow path 544 is provided with a recovery flow path 924 that is connected through the recovery port 328 to a flow path 922 that communicates with the connection portion 330 between the circulation pump 322 and the second pressure control chamber 528. Therefore, the ink in the second pressure control chamber 528 can be recovered into the ink supply unit 20 through the recovery flow path 924, the flow path 922, and the recovery tube 24 by driving the pump 904. In this manner, in this embodiment, it is possible to supply liquid stored in the ink tank 18 to the first pressure control chamber 508, and it also functions as a supply unit capable of recovering ink in the first pressure control chamber 508, the second pressure control chamber 528, and the recording element substrate 302.

[0058] <Configuration of the control system of the recording device> Next, a description will be given of the configuration of the control system of the recording device 10. Fig. 10 is a block diagram showing the configuration of the control system of the recording device.

[0059] The recording apparatus 10 is connected to a data supplying device such as a host computer (hereinafter referred to as "host PC") 1004 via an interface 1002. Various data transmitted from the host PC 1004 and control signals related to various processes executed by the recording apparatus 10 are input to a control unit 1006. The control unit 1006 includes a CPU 1008 that executes various control programs, and a ROM 1010 that stores the control programs executed by the CPU 1008. The control unit 1006 also includes a RAM 1012 that stores various data such as input image data, intermediate product multi-value gradation data, a multi-pass mask, and program control variables, and is used as a work area for the CPU 1008.

[0060] The recording device 10 includes a motor driver 1016 that drives a transport motor 1014. The recording medium M is transported in the Y direction (see FIG. 1) by driving the transport motor 1014. The motor driver 1016 is controlled by a CPU 1008, which controls the driving of the transport unit via the motor driver 1016. The recording device 10 also includes a motor driver 1020 that drives a carriage motor 1018 that moves the carriage 14 in the X direction (see FIG. 1). The motor driver 1020 is controlled by the CPU 1008, which controls the movement of the carriage 14 (recording head 16) via the motor driver 1020.

[0061] The recording apparatus 10 includes a driving driver 1026 for driving a pump driving unit 1024 for driving a pump 1022. In the description using FIG. 10, the circulation pump 322 and the pump 904 are shown as pumps 1022 for ease of understanding. The driving driver 1026 is controlled by the CPU 1008, and the CPU 1008 thereby controls the driving of the circulation pump 322 and the pump 904. The recording apparatus 10 also includes a driving driver 1032 for driving a valve driving unit 1030 for driving a valve 1028. In the description using FIG. 10, the supply valve 906 and the recovery valve 910 are shown as valves 1028 for ease of understanding. The driving driver 1032 is controlled by the CPU 1008, and the CPU 1008 thereby controls the driving of the supply valve 906 and the recovery valve 910. The recording apparatus 10 also includes a head driver 1034 for driving the recording head 16. The head driver 1034 is controlled by the CPU 1008, whereby the print heads 16a and 16b are subjected to various controls, such as ink ejection timing, by the CPU 1008.

[0062] <1st cycle> In the recording device 10, in the above-described ink circulation path, a first circulation is performed during a recording operation to circulate the ink so as to suppress thickening of the ink in the ejection openings 410 that are not ejecting ink while enabling ink to be ejected stably from the ejection openings 410. Note that the first circulation is not limited to being performed only during a recording operation. For example, in order to eliminate thickening of the ink in the ejection openings 410 during a non-recording operation, the first circulation may be performed at a predetermined timing, such as a timing when a certain period of time has elapsed without a new recording operation being performed after the most recent recording operation. Note that the first circulation is performed by the recording heads 16a and 16b.

[0063] In the first circulation, first, the CPU 1008 opens the supply valve 906 to communicate the supply path 902 with the ink tank 18, and closes the recovery valve 910 to not communicate the supply path 902 with the recovery path 908 (see FIG. 9). Next, the CPU 1008 drives the pump 904 to transfer the ink stored in the ink tank 18 to the print head 16b via the supply tube 22. The subsequent flow of ink will be described with reference to the arrows in FIG. 9.

[0064] The ink transferred to the recording head 16b passes through the flow path 912 and the filter 540, and is then supplied to the first pressure control mechanism 320 and the first pressure control chamber 508. This supply of ink causes the first pressure control mechanism 320 to adjust the pressure in the first pressure control chamber 508 to a predetermined pressure (negative pressure). That is, the first pressure control mechanism 320 controls the pressure in the first pressure control chamber 508 to a first negative pressure. The CPU 1008 also drives the circulation pump 322 to transfer ink from the second pressure control chamber 528 to the first pressure control chamber 508 via the flow path 544. This transfer of ink by the circulation pump 322 causes the second pressure control mechanism 500 to adjust the pressure in the second pressure control chamber 528 to a pressure lower than the pressure in the first pressure control chamber 508. In other words, the second pressure control mechanism 500 adjusts the pressure inside the second pressure control chamber 528 to a second negative pressure that indicates a pressure lower than the first negative pressure, i.e., a second negative pressure that indicates a negative pressure value higher than the first negative pressure.

[0065] As a result, the negative pressure on the supply flow path side to the pressure chamber 408, which is connected to the first pressure control chamber 508, becomes lower than the negative pressure on the recovery flow path side from the pressure chamber 408, which is connected to the second pressure control chamber 528, and a flow of ink occurs from the supply flow path side to the recovery flow path side via the pressure chamber 408. The configuration on the supply flow path side to the pressure chamber 408 includes the first air bubble storage flow path 914, the connection flow path 916, the opening 422, the supply flow path 418, and the inlet 414. The configuration on the recovery flow path side from the pressure chamber 408 includes the outlet 416, the recovery flow path 420, the opening 422, the connection flow path 918, and the second air bubble storage flow path 920. The first air bubble storage flow path 914 and the second air bubble storage flow path 920 have a volume capable of temporarily storing air bubbles generated in the circulating ink.

[0066] Therefore, in the first circulation, an ink flow is generated from the first pressure control chamber 508 toward the pressure chamber 408 via the first bubble storage channel 914, the connection channel 916, and the supply channel 418. Also, an ink flow is generated from the pressure chamber 408 toward the second pressure control chamber 528 via the recovery channel 420, the connection channel 918, and the second bubble storage channel 920. Furthermore, an ink flow is generated from the first pressure control chamber 508 toward the second pressure control chamber 528 through the channel 542. Then, when the ink circulating through the circulation channel is discharged to the outside from the discharge port 410 and the pressure in the circulation channel is reduced, the ink supplied from the supply tube 22 flows into the first pressure control chamber 508 through the filter 540. Note that a recovery channel 924 communicating with the recovery port 328 is connected to the channel 544 between the circulation pump 322 and the second pressure control chamber 528. However, in the first circulation, because the recovery valve 910 is in a closed state in the recovery path 908 to which the recovery flow path 924 is connected via the recovery tube 24, ink does not flow into the recovery path 924, the recovery tube 24, and the recovery path 908. Thus, in this embodiment, in the first circulation, the control unit 1006 (CPU 1008) functions as a circulation control unit that can control the circulation of ink between the first pressure control chamber 508, the second pressure control chamber 528, and the recording element substrate 302.

[0067] In the first circulation, the ink located in the ejection port 410 not ejecting ink and the pressure chamber 408 communicating with the ejection port 410 is recovered through the recovery flow path 420 by the flow of ink as described above. Therefore, it is possible to suppress the increase in viscosity of the ink caused by the evaporation of the liquid component in the ink from the ejection port 410. In addition, in the first circulation, even if bubbles or thickened ink are generated in the pressure chamber 408 and the ejection port 410, they are recovered together with the circulating ink. As a result, thickened ink and bubbles flow into the flow path and the pressure control chamber in the circulation path. Since a large amount of ink is stored in the circulation path compared to the thickened ink, the viscosity is uniformed to a range that does not affect the ejection. In addition, since bubbles have buoyancy, they are stored in the first bubble storage flow path 914, the second bubble storage flow path 920, the first pressure control chamber 508, and the second pressure control chamber 528, and a state in which they do not affect the ejection of ink from the ejection port 410 can be maintained.

[0068] By performing the first circulation, it is possible to suppress the execution of preliminary ejection, which is the ejection of ink that does not contribute to printing, in order to suppress thickening of the ink in the pressure chambers 408 and the ejection ports 410, and it is possible to suppress the consumption of ink. Furthermore, since the pressure in the supply flow path 418 and the recovery flow path 420 is in a controlled state in the printing element substrate 302, it is possible to stably supply ink to the pressure chambers 408, and it is possible to stably eject ink from the ejection ports 410.

[0069] <2nd cycle> For example, in the case of white ink, which is prone to settling, the first circulation can suppress settling in some of the flow paths through which the ink continues to circulate. In addition, in the ink tank 18 that stores the white ink, the settling can be eliminated by having the user remove the ink tank 18 and shake the ink tank 18 to stir it, or by providing the ink tank 18 with a stirring function. However, in the first circulation, there may be a time when the ink does not flow in the flow path connecting the ink tank 18 and the first pressure control mechanism 320. In this case, there is a risk that the material contained in the white ink (specifically, the pigment) may settle in the flow path. In addition, if the time during which the ink circulation in the circulation path stops, such as when the recording device 10 is turned off, exceeds a predetermined time, there is a risk that the material contained in the white ink may settle in the circulation path.

[0070] When the first circulation is used to eliminate the sedimentation, for example, it is possible to increase the pump frequency of the circulation pump 322 and increase the flow rate of the circulating ink to eliminate the sedimentation caused by stirring the flow of the ink in the flow path. However, in the circulation path, the first pressure control mechanism 320 and the second pressure control mechanism 500 control the first pressure control chamber 508 and the second pressure control chamber 528 to a predetermined pressure difference. Therefore, in the flow path from the first pressure control chamber 508 to the second pressure control chamber 528 through the recording element substrate 302, the ink flow rate does not increase, and there is a risk that the ink flow will not eliminate the sedimentation. Note that in the flow path circulating the first pressure control chamber 508, the flow path 542, the second pressure control chamber 528, and the flow path 544, the ink flow rate can be improved by increasing the pump frequency of the circulation pump 322. Therefore, in the flow path, the ink flow can eliminate the sedimentation.

[0071] Therefore, in this embodiment, a second circulation is performed to eliminate the sedimentation that occurs in the flow path connecting the ink supply unit 20 and the first pressure control chamber 508 and the flow path from the first pressure control chamber 508 to the second pressure control chamber 528 via the recording element substrate 302. The flow path connecting the ink supply unit 20 and the first pressure control chamber 508 is specifically a flow path from the supply path 902 to the first pressure control mechanism 320 through the supply tube 22, the flow path 912, the supply port 324, the filter 540, etc. The flow path from the first pressure control chamber 508 to the second pressure control chamber 528 via the recording element substrate 302 is specifically a flow path from the first pressure control chamber 508 to the second pressure control chamber 528 through the first air bubble storage flow path 914, the flow path in the recording element substrate 302, and the second air bubble storage flow path 920, etc. The second circulation will be described in detail below.

[0072] In the recording device 10, the second circulation is performed at a predetermined timing when the recording operation has not been performed for a long time. The predetermined timing when the recording operation has not been performed for a long time is, for example, a timing when the ink that is prone to sedimentation has started to sediment to such an extent that it can be eliminated by the second circulation. Specifically, for example, the timing is a timing after the most recent recording operation is completed, which is after the time when the ink that is prone to sedimentation starts to sedimentation, and a certain time before the time when the sedimentation that has occurred cannot be eliminated by the second circulation. Since the recovery flow path 924 is used in the second circulation, the second circulation cannot be performed in the recording head 16a. Therefore, the second circulation is performed only in the circulation path including the flow path in the circulation unit 306a of the recording head 16b.

[0073] In the second circulation, first, the CPU 1008 closes the supply valve 906 to put the supply path 902 and the ink tank 18 in a non-communicating state, and opens the recovery valve 910 to put the supply path 902 and the recovery path 908 in a communicating state (see FIG. 11). FIG. 11 is a diagram for explaining the flow of ink in the second circulation. As a result, even if the pump 904 is driven, the ink stored in the ink tank 18 does not flow into the circulation path. Next, the CPU 1008 drives the pump 904 to start circulating the ink. Here, on the upstream side of the pump 904 (upstream side in the direction of ink flow by the pump 904), the recovery path 908 is connected to the supply path 902, and the recovery valve 910 in the recovery path 908 is in an open state. Also, on the upstream side of the pump 904, the ink tank 18 is connected to the supply path 902, and the supply valve 906 in the supply path 902 is in a closed state. Therefore, even when the pump 904 is driven, the ink stored in the ink tank 18 does not flow into the circulation path. Furthermore, by driving the pump 904, the ink in the second pressure control chamber 528 is sucked through the recovery flow path 924, the recovery tube 24, and the recovery path 908, and the ink that has been sucked and flowed into the recovery path 908 is transported to the recording head 16b through the supply tube 22.

[0074] The ink transferred to the recording head 16b passes through the flow path 912 and the filter 540, and is then supplied to the first pressure control mechanism 320 and the first pressure control chamber 508. Then, the ink in the first pressure control chamber 508 flows into the second pressure control chamber 528 through the first air bubble storage flow path 914, the connection flow path 916, the supply flow path 418, the pressure chamber 408, the recovery flow path 420, the connection flow path 918, and the second air bubble storage flow path 920. Also, the ink in the first pressure control chamber 508 flows into the second pressure control chamber 528 via the flow path 542 and the second pressure control mechanism 500.

[0075] Furthermore, the ink in the second pressure control chamber 528 flows into the recovery path 908 via the recovery flow passage 924 and the recovery tube 24 due to the drive of the pump 904 and the ink flowing in from the first pressure control chamber 508. Then, the ink that has flowed into the recovery path 908 flows out into the supply tube 22 via the supply path 902. This causes the ink to circulate between the ink supply unit 20 and the recording head 16b. Thus, in this embodiment, during the second circulation, the control unit 1006 (CPU 1008) functions as a circulation control unit that can control the circulation of ink between the first pressure control chamber 508, the second pressure control chamber 528, the recording element substrate 302, and the ink supply unit 20.

[0076] As described above, in the second circulation, the pump 904 is driven to recover ink in the second pressure control chamber 528 through the recovery path 908, the recovery tube 24, and the recovery flow path 924. In the second circulation, the negative pressure value applied to the second pressure control chamber 528 by the pump 904 is higher than the negative pressure value applied to the second pressure control chamber 528 by the circulation pump 322 during the first circulation. As a result, the flow rate of ink passing through the recording element substrate 302 from the first pressure control chamber 508 via the first bubble storage flow path 914 and the like and flowing from the recording element substrate 302 into the second pressure control chamber 528 via the second bubble storage flow path 920 and the like becomes higher than that in the first circulation. In addition, the flow rate of ink passing through the flow path 542 from the first pressure control chamber 508 toward the second pressure control chamber 528 becomes higher than that in the first circulation. Therefore, in the second circulation, it is possible to eliminate sedimentation that occurs in the flow path from the first pressure control chamber 508 to the second pressure control chamber 528 through the flow path in the recording element substrate 302, which cannot be achieved by increasing the pump frequency of the circulation pump 322 in the first circulation. Moreover, even if the sedimentation was eliminated in the first circulation, it can be eliminated in a shorter time in the second circulation. Moreover, in the flow path from the ink supply unit 20 to the first pressure control mechanism 320, where ink does not circulate in the first circulation, ink is circulated in the second circulation, so that sedimentation in the flow path can also be eliminated.

[0077] In the second circulation, the flow rate of ink in the flow path passing through the first bubble storage flow path 914, the connection flow path 916, the supply flow path 418, the pressure chamber 408, the recovery flow path 420, the connection flow path 918, and the second bubble storage flow path 920 can be increased more than in the first circulation. In addition, the flow rate of ink in the flow path passing through the first pressure control chamber 508 and the flow path 542 and the second pressure control mechanism 500 can be increased more than in the first circulation. As a result, in the second circulation, it becomes possible to more reliably eliminate sedimentation that occurs in these flow paths than in the first circulation. In addition, in the second circulation, it is possible to circulate ink also in the flow path from the ink supply unit 20 to the first pressure control mechanism 320. As a result, in the second circulation, it becomes possible to eliminate sedimentation that occurs in the flow paths that cannot be eliminated in the first circulation.

[0078] <Action and effect> In this embodiment, the recording head 16b is configured to circulate the ink supplied from the ink supply unit between the first pressure control chamber and the second pressure control chamber, which are adjusted to a negative pressure with a predetermined pressure difference between them, and a flow path formed in the recording element substrate. Furthermore, a recovery path into which the ink recovered via the recovery tube 24 flows is connected to a supply path for supplying ink from an ink tank to a supply tube, and the ink is circulated in a circulation path including these flow paths. Then, during a recording operation, a first circulation is performed to circulate the ink in the recording head 16b while the ink to be ejected is supplied, so as to maintain the pressure difference between the first pressure control chamber and the second pressure control chamber. Furthermore, when a recording operation is not performed for a predetermined time or more, a second circulation is performed to circulate the ink at a flow rate higher than that during the first circulation by recovering the ink from the second pressure control chamber and supplying the ink to the first pressure control chamber. As a result, in the recording device 10, it is possible to suppress the thickening of the ink, to stably eject the ink, and to eliminate the settling of the ink-containing material that occurs in the circulation path.

[0079] Second embodiment Next, a liquid ejection head according to a second embodiment will be described with reference to Figures 12 to 14. In the following description, the same reference numerals as those used in the first embodiment are used for the same or corresponding configurations as those of the recording apparatus described in the first embodiment, and detailed description thereof will be omitted.

[0080] The recording apparatus 10 according to the second embodiment is different from the first embodiment in that a recovery passage for recovering ink from a passage 544 in a circulation unit 306a is connected between a circulation pump 322 and a first pressure control chamber 508.

[0081] 12 is a diagram for explaining an ink circulation path provided in the recording device 10 according to the second embodiment. In the second embodiment, a recovery flow path 1224 is provided that connects the flow path 544 and the recovery port 328 and leads the ink in the flow path 544 to the recovery tube 24. The recovery flow path 1224 is provided so as to connect the flow path 544 and the recovery port 328 from between the circulation pump 322 and the first pressure control chamber 508 in the flow path 544. Since the other configurations of the recording device 10 in this embodiment and the first circulation (see the arrows in FIG. 12) are the same as those in the first embodiment, the following description will be given in detail of the second circulation that differs from the first embodiment.

[0082] <2nd cycle> FIG. 13 is a diagram for explaining the second circulation in the recording apparatus 10 according to the second embodiment. FIG. 14 is a diagram for explaining the flow of ink in the circulation unit 306a. In the second circulation, first, the CPU 1008 closes the supply valve 906 to put the supply path 902 and the ink tank 18 in a non-communicating state, and opens the recovery valve 910 to put the supply path 902 and the recovery path 908 in a communicating state. As a result, even if the pump 904 is driven, the ink stored in the ink tank 18 does not flow into the circulation path. Next, the CPU 1008 drives the pump 904 to start the circulation of the ink. By driving the pump 904 to execute the circulation of the ink, the negative pressure of the first pressure control chamber 508 becomes higher (the pressure is lower) than that of the second pressure control chamber 528 in the circulation path. In this embodiment, by driving the pump 904 to start the circulation of the ink, the ink is collected from the first pressure control chamber 508 to the ink supply unit 20 via the recovery flow path 1224. As a result, in the circulation path, the negative pressure in the first pressure control chamber 508 becomes higher (the pressure becomes lower) than that in the second pressure control chamber 528, and ink flows in the opposite direction to that in the first circulation (see the arrow in FIG. 13).

[0083] Specifically, when the pump 904 is driven, the ink in the first pressure control chamber 508 flows out into the recovery tube 24 via the flow path 544 and the recovery flow path 1224, etc. (see arrow L in FIG. 14(a)). As a result, the first pressure control chamber 508 has a lower pressure than the second pressure control chamber 528, and when the pressure in the first pressure control chamber 508 reaches the opening pressure of the first pressure control valve 502, the first pressure control valve 502 opens the orifice 548 (see FIG. 14(a)). As a result, ink supplied via the supply tube 22 flows into the first pressure control chamber 508 via the filter 540 and the first pressure control mechanism 320 (see arrow M in FIG. 14(a)).

[0084] The first pressure control chamber 508 is connected to the second pressure control chamber 528 via the second pressure control mechanism 500 and the flow path 542, and is also connected to the flow path of the recording element substrate 302 via the first air bubble storage flow path 914 and the connection flow path 916. Therefore, when the pressure in the first pressure control chamber 508 becomes lower than the pressure in the second pressure control chamber 528, ink flows from these flow paths toward the first pressure control chamber 508 (see arrows N and S in FIG. 14(a)). That is, ink flows toward the first pressure control chamber 508 via the second pressure control mechanism 500 and the flow path 542 (see arrow N in FIG. 14(a)). In addition, ink flows from the second pressure control chamber 528, through the second bubble storage channel 920, the connecting channel 918, the recovery channel 420, the pressure chamber 408, the supply channel 418, the connecting channel 916, and the first bubble storage channel 914 toward the first pressure control chamber 508 (see arrows in Figure 13).

[0085] When an amount of ink flows from the flow path 542 toward the first pressure control chamber 508, the second pressure control valve 522 of the second pressure control mechanism 500 at a valve opening pressure, the second pressure control valve 522 opens the orifice 546 (see FIG. 14(b)). As a result, the ink in the second pressure control chamber 528 flows out to the first pressure control chamber 508 via the orifice 546, and the pressure in the second pressure control chamber 528 becomes approximately the same as the pressure in the first pressure control chamber 508. When the pressures in the first pressure control chamber 508 and the second pressure control chamber 528 become approximately the same, the flow of ink from the second pressure control chamber 528 toward the flow path 542 and the second bubble storage flow path 920 stops. Then, only the ink is circulated through the first pressure control mechanism 320, the first pressure control chamber 508, the recovery flow path 1224, the recovery tube 24, the recovery path 908, the supply path 902, the supply tube 22, and the filter 540. This circulation can eliminate sedimentation in the flow path from the supply path 902 to the first pressure control chamber 508, for example, removing sediment in the supply tube 22, the connection part 326, the first pressure control valve 502, the orifice 548, etc.

[0086] The amount of ink flowing from the second pressure control chamber 528 to the flow path 542 and the second air bubble storage flow path 920 corresponds to the volume of the second pressure control chamber 528 when the second control spring 532 is expanded. Therefore, the volume of the second pressure control chamber 528, that is, the displacement stroke amount of the second control spring 532, is adjusted so that the ink flow from the second pressure control chamber 528 can reliably eliminate the settling that occurs from the second pressure control chamber 528 to the first pressure control chamber 508. In addition, in the second circulation, ink flows into the first pressure control chamber 508 via the first air bubble storage flow path 914, so that the air bubbles that have accumulated in the supply flow path 418 can be discharged. The air bubbles that have accumulated in the supply flow path 418 are usually removed by discharging the ink from the ejection port 410. Therefore, by performing the second circulation in this embodiment, it becomes unnecessary to perform an ink discharge operation for removing air bubbles remaining in the supply flow path 418, and the amount of ink consumed is reduced.

[0087] <Action and effect> In the first embodiment, the recovery flow path 924 is connected between the circulation pump 322 and the second pressure control chamber 528 in the flow path 544. In contrast to this, in the second embodiment, the recovery flow path 1224 is connected between the circulation pump 322 and the first pressure control chamber 508 in the flow path 544. Therefore, in the second embodiment, it is possible to generate a flow of ink in the opposite direction to that in the first embodiment in the second circulation. This makes it possible to achieve the same effects as the first embodiment, and also makes it possible to remove air bubbles remaining in the supply flow path 418 without discharging the ink.

[0088] (Other embodiments) The above embodiment may be modified as shown in the following (1) to (7).

[0089] (1) In the first embodiment, the recovery flow path 924 is connected to a predetermined position in the flow path 544 between the second pressure control chamber 528 and the circulation pump 322, but the present invention is not limited to this. For example, the recovery flow path 924 may be connected to any location between the pressure chamber 408 of the recording element substrate 302 and the circulation pump 322, including the recovery flow path 420, the connection flow path 918, the second bubble storage flow path 920, and the second pressure control chamber 528. In other words, the recovery flow path 924 may be connected to any location downstream of the pressure chamber 408 and upstream of the circulation pump 322.

[0090] In the second embodiment, the recovery flow path 1224 is connected to a predetermined position between the circulation pump 322 and the first pressure control chamber 508 in the flow path 544, but the present invention is not limited to this. For example, the recovery flow path 924 may be connected anywhere between the pressure chamber 408 of the recording element substrate 302 including the supply flow path 418, the connection flow path 916, the first bubble storage flow path 914, and the first pressure control chamber 508 and the circulation pump 322. In other words, the recovery flow path 924 may be connected anywhere upstream of the pressure chamber 408 and downstream of the circulation pump 322.

[0091] The above-mentioned "upstream side" and "downstream side" refer to the upstream side and downstream side in the direction in which the ink flows when circulating during the first circulation.

[0092] (2) In the above embodiment, the recovery path 908 into which ink flows in is connected via the recovery tube 24 to the supply path 902 connected to the ink tank 18, but the present invention is not limited to this. For example, a sub-tank capable of temporarily storing ink flowing out from the recovery path 908 may be provided, and the ink in the sub-tank may flow out to the supply path 902. In this case, a recovery valve 910 is provided between the sub-tank and the supply path 902. Alternatively, the recovery path 908 may be connected to the ink tank 18, and ink may flow out from the recovery path 908 into the ink tank 18. In this case, the recovery valve 910 is provided between the recovery path 908 and the ink tank 18, and the supply valve 906 is not provided. This allows air bubbles generated in the circulation path to be collected in the sub-tank or the ink tank 18, making it difficult for air bubbles to get mixed into the circulating ink. In order to improve the efficiency of collecting air bubbles, for example, the collection channels 924 and 1224 may be connected to the first air bubble storage channel 914 and the second air bubble storage channel 920 in the vicinity of their downstream sides.

[0093] (3) Although not specifically described in the first embodiment, in the second circulation, the circulation pump 322 may be driven with a pump frequency higher than that in the first circulation. This reliably increases the flow rate of ink circulating through the first pressure control chamber 508, the flow path 542, the second pressure control chamber 528, and the flow path 544, and reliably removes, for example, sediment that accumulates in the pressure control valves 502, 522 and the orifices 546, 548. In the first embodiment, the second circulation in which the circulation pump 322 is not driven and the second circulation in which the circulation pump 322 is driven with a pump frequency higher than that in the first circulation may be selectively executed, or both may be executed.

[0094] (4) In the above embodiment, a so-called serial scan type recording device has been described as an example, which records by discharging ink while moving the recording head 16 in the X direction onto the recording medium M transported in the Y direction. However, the present invention can also be applied to a so-called full line type recording device that uses a recording head in which the ejection ports 410 are arranged over a length corresponding to the width direction of the recording medium M. When applied to a full line type recording device, some of the components that are integrally provided in the recording head 16b, such as the first pressure control chamber 508, the second pressure control chamber 528, the recording element substrate 302, and the circulation pump 322, may be provided separately.

[0095] (5) In the above embodiment, the first air bubble storage channel 914 is provided between the first pressure control chamber 508 and the recording element substrate 302 as an air bubble storage section for storing air bubbles in the ink. In addition, the second air bubble storage channel 920 is provided between the second pressure control chamber 528 and the recording element substrate 302. However, the air bubble storage section may be configured to have either the first air bubble storage channel 914 or the second air bubble storage channel 920.

[0096] (6) In the above embodiment, the circulation unit 306a capable of recovering ink to the ink supply unit 20 is used in the print head 16b only for the white ink that is prone to settling, but this is not limited to this. For example, the circulation unit 306a may also be used for the light cyan ink and light magenta ink that are less prone to settling. In this case, under the control of the control unit 1006 (CPU 1008), the first circulation is performed for the white ink, light cyan ink, and light magenta ink at the timing of performing the first circulation. Furthermore, at the timing of performing the second circulation, the second circulation is performed for the white ink, and the second circulation is not performed for the light cyan ink and light magenta ink.

[0097] (7) The above embodiment and the various configurations shown in (1) and (6) above may be combined as appropriate.

[0098] The disclosure of the above embodiment includes the following configurations and methods. (Configuration 1) a first pressure control chamber controlled to a first negative pressure; a second pressure control chamber connected to the first pressure control chamber via a flow path and controlled to a second negative pressure lower than the first negative pressure; a discharge means capable of discharging liquid supplied from the first pressure control chamber from a discharge port and recovering liquid not discharged from the discharge port into the second pressure control chamber; a supply means capable of supplying the stored liquid to the first pressure control chamber and recovering the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means; a circulation control means capable of controlling the circulation of liquid among the first pressure control chamber, the second pressure control chamber, the discharge means, and the supply means, The circulation control means includes: a first circulation in which liquid is returned from the first pressure control chamber through the discharge means and the second pressure control chamber to the first pressure control chamber by utilizing a pressure difference between the first pressure control chamber and the second pressure control chamber; a second circulation in which liquid in the first pressure control chamber, the second pressure control chamber, and the ejection means is recovered to the supply means while supplying liquid to the first pressure control chamber, without the first pressure control chamber and the second pressure control chamber being controlled to their corresponding negative pressures. (Configuration 2) a flow path connecting the first pressure control chamber and the second pressure control chamber includes a flow path capable of transporting liquid from the first pressure control chamber to the second pressure control chamber by a first pump, The liquid ejection device described in configuration 1, characterized in that in the second circulation, the liquid in the first pressure control chamber, the second pressure control chamber, and the ejection means is recovered from a predetermined position in the ejection means downstream of a pressure chamber in which energy for ejecting the liquid from the ejection port is imparted to the liquid in the direction in which the liquid flows during the first circulation, and upstream of the first pump. (Configuration 3) 3. The liquid ejection device according to configuration 2, wherein the predetermined position is located between the first pump and the second pressure control chamber. (Configuration 4) In the second circulation, a negative pressure is generated by the supply means to recover the liquid, A liquid ejection device as described in configuration 2 or 3, characterized in that a negative pressure value applied to the second pressure control chamber by the supply means during the second circulation is higher than a negative pressure value applied to the second pressure control chamber by the first pump during the first circulation. (Configuration 5) a flow path connecting the first pressure control chamber and the second pressure control chamber includes a flow path capable of transporting liquid from the first pressure control chamber to the second pressure control chamber by a first pump, The liquid ejection device described in configuration 1, characterized in that in the second circulation, the liquid in the first pressure control chamber, the second pressure control chamber, and the ejection means is recovered from a predetermined position in the ejection means upstream of a pressure chamber in which energy for ejecting the liquid from the ejection port is imparted to the liquid, and downstream of the first pump, in the direction in which the liquid flows during the first circulation. (Configuration 6) 6. The liquid ejection device according to configuration 5, wherein the predetermined position is located between the first pump and the first pressure control chamber. (Configuration 7) The supply means is A storage means for storing a liquid; 7. The liquid ejection device according to any one of configurations 1 to 6, further comprising: a second pump capable of transporting the liquid stored in the storage means and the recovered liquid to the first pressure control chamber. (Configuration 8) The supply means is When the first circulation is performed, the transfer of the liquid stored in the storage means to the first pressure control chamber is permitted, and the inflow of the liquid to be recovered is restricted. The liquid ejection device described in configuration 7, characterized in that when the second circulation is performed, the transfer of the liquid stored in the storage means to the first pressure control chamber is regulated and the inflow of the recovered liquid is permitted. (Configuration 9) The supply means further includes a storage portion capable of storing the liquid to be collected, The liquid ejection device described in configuration 7, characterized in that in the second circulation, the liquid recovered and flowing into the supply means flows into the storage section and is then transported from the storage section to the first pressure control chamber by the second pump. (Configuration 10) The liquid ejection device described in configuration 7, characterized in that in the second circulation, the liquid recovered and flowing into the supply means flows into the storage means, and the liquid in the storage means is transported to the first pressure control chamber by the second pump. (Configuration 11) The first pressure control chamber and the second pressure control chamber are A pressure control mechanism for controlling the pressure in the chamber that is controlled to a negative pressure; 11. The liquid ejection device according to any one of configurations 1 to 10, further comprising: a variable membrane that varies a volume within the chamber in response to a pressure within the chamber. (Configuration 12) The pressure control mechanism includes: an orifice for admitting liquid into the chamber; a valve that opens the orifice to allow liquid to flow into the chamber when the pressure falls below a predetermined pressure due to the outflow of liquid from the chamber, and closes the orifice to prevent liquid from flowing into the chamber when the pressure exceeds the predetermined pressure due to the inflow of liquid into the chamber; 12. The liquid ejection device according to configuration 11, further comprising: a spring that biases the variable membrane in a direction that expands the volume of the chamber. (Configuration 13) A liquid ejection device as described in configuration 12, characterized in that the volume of the second pressure control chamber when the spring is extended corresponds to an amount of liquid that can eliminate settling of liquid-containing material that occurs from the second pressure control chamber to the first pressure control chamber due to the flow of ink by the second circulation. (Configuration 14) A liquid ejection device according to any one of configurations 1 to 13, characterized in that a bubble storage means capable of storing bubbles generated in the liquid is disposed at least either between the first pressure control chamber and the ejection means or between the second pressure control chamber and the ejection means. (Configuration 15) 15. The liquid ejection device according to any one of configurations 1 to 14, wherein the first circulation is performed during an operation of ejecting liquid from the ejection port. (Configuration 16) 16. The liquid ejection device according to claim 1, wherein the second circulation is performed when a period during which no operation of ejecting liquid from the ejection port is performed exceeds a predetermined period. (Configuration 17) The liquid ejection device described in configuration 16, characterized in that the specified time is a time after the time when the contained material in the liquid used begins to settle and a certain time before the time when the resulting settling can no longer be resolved by the second circulation. (Configuration 18) 18. The liquid ejection device according to claim 1, wherein the first pressure control chamber, the second pressure control chamber, and the ejection means are integrally provided in a liquid ejection head together with a flow path for circulating liquid. (Configuration 19) 19. The liquid ejection apparatus according to configuration 18, wherein the liquid ejection head ejects liquid from the ejection openings in the ejection means while moving in a predetermined direction. (Configuration 20) The liquid ejection device is capable of ejecting a plurality of liquids, the first pressure control chamber, the second pressure control chamber, the discharge means, and the supply means are provided for each of a plurality of liquids; 20. The liquid ejection device according to any one of configurations 1 to 19, wherein the circulation control means executes the first circulation for all liquids and executes the second circulation for a specified liquid. (Configuration 21) 21. The liquid ejection device according to configuration 20, wherein the predetermined liquid is a liquid in which sedimentation of contained materials occurs. (Configuration 22) a first pressure control chamber controlled to a first negative pressure; a second pressure control chamber connected to the first pressure control chamber via a flow path and controlled to a second negative pressure lower than the first negative pressure; a discharge means capable of discharging the liquid supplied from the first pressure control chamber from a discharge port and recovering the liquid not discharged from the discharge port into the second pressure control chamber, a first circulation in which liquid is returned from the first pressure control chamber through the discharge means and the second pressure control chamber to the first pressure control chamber by utilizing a pressure difference between the first pressure control chamber and the second pressure control chamber; a second circulation in which liquid is recovered in the first pressure control chamber, the second pressure control chamber, and the ejection means while liquid is supplied to the first pressure control chamber, without the first pressure control chamber and the second pressure control chamber being controlled to their corresponding negative pressures. [Explanation of symbols]

[0099] 10 Recording Device 20 Ink supply unit 302 Printing element substrate 322 Circulation Pump 508 First Pressure Control Room 528 Second Pressure Control Room 542, 544 Flow path

Claims

1. A first pressure control chamber controlled to a first negative pressure, A second pressure control chamber is connected to the first pressure control chamber via a flow path and is controlled to a second negative pressure that is lower than the first negative pressure, A discharge means capable of discharging liquid supplied from the first pressure control chamber from a discharge port, and recovering liquid that was not discharged from the discharge port into the second pressure control chamber, A supply means capable of supplying the liquid to be stored to the first pressure control chamber, and capable of recovering the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means, The system includes a circulation control means capable of controlling the circulation of liquid between the first pressure control chamber, the second pressure control chamber, the discharge means, and the supply means, The aforementioned circulation control means is A first circulation is performed by utilizing the pressure difference between the first pressure control chamber and the second pressure control chamber to return the liquid from the first pressure control chamber through the discharge means and the second pressure control chamber back to the first pressure control chamber, A liquid dispensing device characterized in that, while supplying liquid to the first pressure control chamber, the liquid in the first pressure control chamber, the second pressure control chamber, and the dispensing means is not controlled to a corresponding negative pressure, and a second circulation is performed in which the liquid is recovered to the supply means.

2. The flow path connecting the first pressure control chamber and the second pressure control chamber includes a flow path capable of transferring liquid from the first pressure control chamber to the second pressure control chamber by the first pump. The liquid discharge device according to claim 1, characterized in that, in the second circulation, the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means is recovered from a predetermined position in the discharge means downstream of the pressure chamber where energy for discharging the liquid from the discharge port is supplied to the liquid, and upstream of the first pump, in the direction in which the liquid flows during the first circulation.

3. The liquid discharge device according to claim 2, characterized in that the predetermined position is located between the first pump and the second pressure control chamber.

4. In the second circulation, the supply means generates negative pressure to recover the liquid. The liquid discharge device according to claim 2, characterized in that the negative pressure value applied to the second pressure control chamber by the supply means during the second circulation is higher than the negative pressure value applied to the second pressure control chamber by the first pump during the first circulation.

5. The flow path connecting the first pressure control chamber and the second pressure control chamber includes a flow path capable of transferring liquid from the first pressure control chamber to the second pressure control chamber by the first pump. The liquid discharge device according to claim 1, characterized in that, in the second circulation, the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means is recovered from a predetermined position upstream of the pressure chamber in the discharge means where energy for discharging the liquid from the discharge port is supplied to the liquid, and downstream of the first pump, in the direction in which the liquid flows during the first circulation.

6. The liquid discharge device according to claim 5, characterized in that the predetermined position is located between the first pump and the first pressure control chamber.

7. The supply means is A storage means for storing liquid, The liquid discharge device according to claim 1, further comprising a second pump capable of transferring the liquid stored in the storage means and the recovered liquid to the first pressure control chamber.

8. The supply means is When the first circulation is performed, the transfer of the liquid stored in the storage means to the first pressure control chamber is permitted, and the inflow of the recovered liquid is restricted. The liquid discharge device according to claim 7, characterized in that when the second circulation is performed, the transfer of the liquid stored in the storage means to the first pressure control chamber is restricted, and the inflow of the recovered liquid is permitted.

9. The supply means further comprises a storage section capable of storing the recovered liquid, The liquid discharge device according to claim 7, characterized in that, in the second circulation, the liquid recovered and flowing into the supply means flows into the storage unit and then is transferred from the storage unit to the first pressure control chamber by the second pump.

10. The liquid discharge device according to claim 7, characterized in that, in the second circulation, the liquid recovered and flowing into the supply means flows into the storage means, and the liquid in the storage means is transferred to the first pressure control chamber by the second pump.

11. The first pressure control chamber and the second pressure control chamber are A pressure control mechanism that controls the pressure inside a room that is controlled to a negative pressure, The liquid dispensing device according to claim 1, further comprising a variable membrane that changes the volume of the chamber in accordance with the pressure inside the chamber.

12. The pressure control mechanism is An orifice for introducing liquid into the aforementioned chamber, A valve that, when the pressure inside the chamber falls below a predetermined level due to the outflow of liquid from the chamber, opens the orifice to allow liquid to flow into the chamber, and when the pressure inside the chamber exceeds the predetermined level due to the inflow of liquid into the chamber, closes the orifice to prevent liquid from flowing into the chamber. The liquid dispensing device according to claim 11, further comprising a spring that biases the variable membrane in a direction that expands the volume of the chamber.

13. The liquid discharge device according to claim 12, characterized in that the volume inside the second pressure control chamber when the spring is extended corresponds to an amount of liquid capable of eliminating the sedimentation of the liquid-containing material generated from the second pressure control chamber to the first pressure control chamber by the liquid flow due to the second circulation.

14. The liquid dispensing apparatus according to claim 1, characterized in that a bubble storage means capable of storing bubbles generated in the liquid is provided between the first pressure control chamber and the dispensing means, and between the second pressure control chamber and the dispensing means.

15. The liquid dispensing device according to claim 1, characterized in that the first circulation is performed during the operation of dispensing liquid from the discharge port.

16. The liquid dispensing device according to claim 1, characterized in that the second circulation is performed when a predetermined time has elapsed during which no liquid is dispensed from the discharge port.

17. The liquid dispensing device according to claim 16, characterized in that the predetermined time is after the time when the contained material begins to settle in the liquid used, and a certain amount of time before the time when the resulting settling can no longer be resolved by the second circulation.

18. The liquid dispensing device according to claim 1, characterized in that the first pressure control chamber, the second pressure control chamber, and the dispensing means are integrally provided with a liquid dispensing head together with a flow path for circulating the liquid.

19. The liquid dispensing device according to claim 18, characterized in that the liquid dispensing head moves along a predetermined direction while dispensing liquid from the dispensing port of the dispensing means.

20. The liquid dispensing device is capable of dispensing multiple liquids. The first pressure control chamber, the second pressure control chamber, the discharge means, and the supply means are provided for each of the multiple liquids. The liquid dispensing device according to claim 1, characterized in that the circulation control means performs the first circulation for all liquids and the second circulation for a predetermined liquid.

21. The liquid dispensing device according to claim 20, characterized in that the predetermined liquid is a liquid that causes the contained material to settle.

22. A first pressure control chamber controlled to a first negative pressure, A second pressure control chamber is connected to the first pressure control chamber via a flow path and is controlled to a second negative pressure that is lower than the first negative pressure, The system includes a discharge means capable of discharging liquid supplied from the first pressure control chamber from a discharge port, and capable of recovering liquid that was not discharged from the discharge port into the second pressure control chamber. A first circulation is performed by utilizing the pressure difference between the first pressure control chamber and the second pressure control chamber to return the liquid from the first pressure control chamber through the discharge means and the second pressure control chamber back to the first pressure control chamber, A liquid discharge head characterized in that, while liquid is supplied to the first pressure control chamber, a second circulation is performed in which the liquid in the first pressure control chamber, the second pressure control chamber, and the discharge means is recovered without the first pressure control chamber and the second pressure control chamber being controlled to their respective negative pressures.

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