Liquid ejection head and recording device

Abstract

To provide a recording device capable of suppressing deterioration in image quality.SOLUTION: Provided is a liquid discharge head 3, including: a recording element substrate having a discharge port 13, an energy generating element for generating energy for discharging a liquid from the discharge port 13, and a supply path for supplying the liquid to the discharge port 13, a recovery path for recovering the liquid not discharged from the discharge port 13; and a pressure control unit that controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path respectively so that the pressure of the liquid at the discharge port 13 becomes negative. The pressure control unit controls the pressure of the liquid in the supply path to positive, and controls the pressure of the liquid in the recovery path to negative.SELECTED DRAWING: Figure 12

Description

[Technical field]

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

[0002] The ejection ports of the recording element substrate (hereinafter sometimes simply referred to as "chip") mounted on the liquid ejection head are open to the atmosphere, and the liquid forms a meniscus at the ejection port by capillary action. Here, to prevent the liquid from leaking from the ejection port, the pressure applied to the liquid at the ejection port is generally controlled to a negative pressure (a pressure lower than that outside the liquid ejection head).

[0003] If the negative pressure (absolute value) applied to the liquid at the ejection port is excessively large, the stability of the ink droplet formation may deteriorate, leading to a deterioration in image quality. Patent Document 1 discloses a recording device that uses a pressure control unit to control the negative pressure applied to the liquid at the ejection port. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 05-075202 Summary of the Invention [Problem to be solved by the invention]

[0005] In the liquid ejection head as described above, in order to suppress deterioration of image quality due to thickening or solidification of the liquid, a flow path may be formed in which the liquid flows past the vicinity of the ejection port of the recording element substrate. In this case, in order to effectively suppress thickening or solidification of the liquid, it is preferable to increase the pressure difference of the liquid between the upstream and downstream sides of the ejection port and increase the flow rate in the vicinity of the ejection port. However, if the negative pressure of the liquid in the flow path downstream of the ejection port is excessively increased in order to increase the pressure difference of the liquid between the upstream and downstream sides of the ejection port, the negative pressure of the liquid in the ejection port will also increase, which may lead to deterioration of image quality.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a recording device capable of suppressing deterioration in image quality. [Means for solving the problem]

[0007] In order to achieve the above object, the liquid ejection head of the present invention comprises: a recording element substrate having an ejection port, an energy generating element that generates energy for ejecting liquid from the ejection port, a supply path that supplies liquid to the ejection port, and a recovery path that recovers liquid not ejected from the ejection port; a pressure control unit that controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the pressure of the liquid at the discharge port becomes negative; Equipped with The pressure control unit controls the pressure of the liquid in the supply path to a positive pressure, and controls the pressure of the liquid in the recovery path to a negative pressure. In order to achieve the above object, the recording apparatus of the present invention comprises: a liquid ejection head including a recording element substrate having an ejection port, an energy generating element that generates energy for ejecting liquid from the ejection port, a supply path that supplies liquid to the ejection port, and a recovery path that recovers liquid not ejected from the ejection port; a pressure control unit that controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the pressure of the liquid at the discharge port becomes negative; Equipped with The pressure control unit controls the pressure of the liquid in the supply path to a positive pressure, It is characterized by controlling the liquid pressure to a negative pressure. Effect of the Invention

[0008] According to the present invention, it is possible to provide a recording device capable of suppressing deterioration in image quality. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a recording apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an ink circulation path of the recording apparatus according to the embodiment. [Diagram 3] 1 is a schematic perspective view of a liquid ejection head according to an embodiment. [Figure 4] FIG. 2 is an exploded perspective view of the liquid ejection head according to the embodiment. [Diagram 5] 4A and 4B are explanatory diagrams of a flow path member according to the embodiment. [Figure 6] 4 is an explanatory diagram of a flow path of a flow path member according to the embodiment. FIG. [Figure 7] FIG. 2 is an explanatory diagram of a discharge module according to the embodiment. [Figure 8] FIG. 2 is an explanatory diagram of a recording element substrate according to the embodiment. [Figure 9] FIG. 2 is a perspective view showing a cross section of a recording element substrate according to the embodiment. [Figure 10] 5A and 5B are explanatory diagrams of a pressure adjustment mechanism according to the embodiment. [Figure 11] 4 is a graph showing an example of the relationship between valve opening and valve resistance. [Figure 12] FIG. 2 is a side view of the liquid ejection head according to the embodiment. [Figure 13] FIG. 4 is a diagram illustrating an example of the configuration of a negative pressure control unit according to the embodiment. [Figure 14] FIG. 2 is an explanatory diagram of a negative pressure control unit of a first configuration example. [Figure 15] FIG. 11 is an explanatory diagram of a negative pressure control unit of a second configuration example. [Figure 16] FIG. 13 is an explanatory diagram of a negative pressure control unit of a third configuration example. [Figure 17] FIG. 13 is an explanatory diagram of a negative pressure control unit of a fourth configuration example. [Figure 18] FIG. 13 is an explanatory diagram of a negative pressure control unit of a fifth configuration example. [Figure 19] 13 is an explanatory diagram of a negative pressure control unit according to a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Note that the dimensions, materials, shapes, and relative positions of the components described in the embodiment may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiment.

[0011] Hereinafter, an embodiment in which the present invention is applied to a liquid ejection head (inkjet head) that ejects liquid such as ink by a thermal method will be described. The thermal method is a method in which liquid is ejected by generating bubbles using a heating element provided in the liquid ejection head. However, the present invention is not limited to liquid ejection heads using the thermal method, and can also be applied to liquid ejection heads using a piezoelectric method or various other liquid ejection methods.

[0012] In the following embodiments, the inkjet recording device is configured to circulate ink as a liquid between the tank and the liquid ejection head. However, for example, instead of circulating the ink, two tanks may be provided on the upstream and downstream sides of the liquid ejection head, and the ink may be caused to flow from one tank to the other tank, thereby causing the ink to flow in the pressure chamber.

[0013] Furthermore, the liquid ejection head in the following embodiments is a so-called line type head, which has a length corresponding to the width of the recording medium. However, the present invention can also be applied to a so-called serial type liquid ejection head, which performs printing while scanning the recording medium. An example of a serial type liquid ejection head is a configuration in which one recording element substrate for black ink and one for color ink are mounted, but this is not limited to this. A short line head that is shorter than the width of the recording medium and in which several recording element substrates are arranged so that the ejection openings overlap in the ejection opening row direction is used. and scanning the image onto a recording medium.

[0014] [Embodiment] <Inkjet recording device> The following describes a printing apparatus 1000 according to an embodiment of the present invention. Fig. 1 is a perspective view showing a schematic configuration of the printing apparatus 1000. The printing apparatus 1000 is an apparatus that ejects liquid, and in particular, is an inkjet printing apparatus that ejects ink to perform printing.

[0015] The recording device 1000 includes a transport unit 1 that transports the recording medium 2, and four line-type liquid ejection heads 3. The liquid ejection heads 3 are arranged so that their longitudinal direction is substantially perpendicular to the transport direction of the recording medium 2. The recording device 1000 is a line-type recording device that performs continuous recording in one pass while transporting multiple recording media 2 continuously or intermittently. The recording media 2 are not limited to cut paper, and may be continuous roll paper. Furthermore, the recording media 2 are not limited to paper, and may be film, etc.

[0016] Each of the four liquid ejection heads 3 is configured to be capable of ejecting one color of ink out of CMYK (cyan, magenta, yellow, black) ink, and the recording device 1000 is capable of full-color printing. An ink flow path for supplying ink to the liquid ejection heads 3 is connected to the liquid ejection heads 3, and is fluidly connected to the main tank 1006 and the buffer tank 1003 (see FIG. 2) through the ink flow path. In addition, an electrical control unit for transmitting power and ejection control signals to the liquid ejection heads 3 is electrically connected to the liquid ejection heads 3. Details of the liquid paths and electrical signal paths of the liquid ejection heads 3 will be described later.

[0017] <Ink circulation system> Next, an ink circulation system in the recording apparatus 1000 will be described. FIG. 2 is a schematic diagram showing an ink circulation path applied to the recording apparatus 1000. The liquid ejection head 3 is fluidically connected to a first circulation pump 1002 through a liquid connection part 111, and is fluidically connected to a second circulation pump 1004 through a liquid connection part 112. The first circulation pump 1002 and the second circulation pump 1004 are each fluidically connected to a buffer tank 1003. In the recording apparatus 1000 of this embodiment, the ink circulates and flows in the order of the liquid ejection head 3, the first circulation pump 1002, the buffer tank 1003, and the second circulation pump 1004. Note that, in FIG. 2, for the sake of simplicity, only a path through which one color of ink flows among CMYK inks is shown, but the recording apparatus 1000 is provided with circulation paths for inks of four colors.

[0018] The buffer tank 1003 is a sub-tank that is fluidly connected to the main tank 1006 via a refill pump 1005. The buffer tank 1003 has an air communication port that connects the inside of the tank with the outside, and is capable of discharging air bubbles in the ink to the outside. When ink is discharged (discharged) from the discharge ports of the liquid discharge head 3 due to a printing operation, suction recovery, or the like and ink is consumed by the liquid discharge head 3, the refill pump 1005 transfers the consumed amount of ink from the main tank 1006 to the buffer tank 1003.

[0019] The first circulation pump 1002 has a role of drawing out ink from inside the liquid ejection head 3 through the liquid connection part 111 of the liquid ejection head 3 and flowing it to the buffer tank 1003. When the liquid ejection head 3 is driven, the first circulation pump 1002 causes a constant amount of ink to flow through the common recovery flow path 212 of the liquid ejection head 3. The common recovery flow path 212 of the liquid ejection head 3 will be described in detail later.

[0020] The second circulation pump 1004 serves to feed ink from the buffer tank 1003 to the liquid connection portion 112 of the liquid ejection head 3. In this manner, the recording apparatus 1000 of this embodiment has In the embodiment, ink is circulated between the liquid ejection head 3 and the buffer tank 1003 by a first circulation pump 1002 and a second circulation pump 1004 .

[0021] The liquid ejection head 3 is composed of a liquid supply unit 220, a negative pressure control unit 230, and a liquid ejection unit 300. The ink flow paths in the liquid ejection head 3 are composed of flow paths formed in each unit. In this embodiment, the negative pressure control unit 230 is mounted on the liquid ejection head 3, but in applying the present invention, the negative pressure control unit 230 may be provided separately from the liquid ejection head 3.

[0022] The liquid supply unit 220 is provided with a liquid connection part 111 connected to a first circulation pump 1002, and a liquid connection part 112 connected to a second circulation pump 1004. Furthermore, a filter 221 for removing foreign matter from the ink being supplied is provided inside the liquid supply unit 220. In this embodiment, a filter 221 is provided for each ink color, and is disposed at a position communicating with the opening of the liquid connection part 112.

[0023] The negative pressure control unit 230 is a pressure control unit (pressure control means) that controls the pressure of ink supplied to the liquid ejection unit 300. The negative pressure control unit 230 is provided between the ink path between the second circulation pump 1004 and the liquid ejection unit 300. The negative pressure control unit 230 has a function of operating to maintain the pressure downstream of the negative pressure control unit 230 (the liquid ejection unit 300 side) at a preset constant pressure when the flow rate of the circulation system fluctuates due to a difference in duty during printing.

[0024] In the vicinity of the ejection port of the liquid ejection head 3, a negative pressure is applied to the ink to form a meniscus in the ejection port in order to prevent the ink from leaking. When the negative pressure of the ink fluctuates, the meniscus surface position in the ejection port fluctuates, and the volume of the ejected ink droplets also fluctuates. If the droplet volume fluctuates significantly, image quality may deteriorate due to the occurrence of uneven density. In addition, if the negative pressure at the ejection port is excessively large, the meniscus surface position may fluctuate significantly, making the formation of the ejected ink droplets unstable, and image quality (print quality) may deteriorate. Therefore, in this embodiment, the negative pressure control unit 230 maintains the pressure of the ink supplied to the liquid ejection unit 300 having the ejection port constant.

[0025] Here, negative pressure refers to pressure lower than atmospheric pressure, and refers to the pressure difference with atmospheric pressure. In the following explanation, a large negative pressure refers to a large difference with respect to atmospheric pressure, and refers to a large absolute value of pressure. Moreover, positive pressure refers to a pressure higher than atmospheric pressure, and refers to the pressure difference with atmospheric pressure.

[0026] 2, the negative pressure control unit 230 includes two pressure adjustment mechanisms 232 (negative pressure adjustment mechanisms) in which different control pressures of ink are set. In the following, of the two pressure adjustment mechanisms 232, the one whose control pressure is set to a relatively high pressure will be referred to as the first pressure adjustment mechanism 232H, and the other whose control pressure is set to a relatively low pressure will be referred to as the second pressure adjustment mechanism 232L, and will be described separately as necessary. Note that the control pressures of the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L are both negative pressures, and the negative pressure control unit 230 is configured so that the negative pressure in the first pressure adjustment mechanism 232H is smaller than the negative pressure in the second pressure adjustment mechanism 232L.

[0027] The first pressure adjustment mechanism 232H is connected to a common supply flow path 211 provided in the liquid discharge unit 300 via the liquid supply unit 220. The second pressure adjustment mechanism 232L is connected to a common recovery flow path 212 provided in the liquid discharge unit 300 via the liquid supply unit 220.

[0028] In this embodiment, a single flow path is formed from the liquid connection part 112 to the filter 221. The flow path is divided downstream of the filter 221. One of the divided flow paths is connected to the first pressure adjustment mechanism 232H, and the other is connected to the second pressure adjustment mechanism 232L. That is, a portion of the ink that has passed through the filter 221 is adjusted to a relatively high pressure by the first pressure adjustment mechanism 232H and flows into the common supply flow path 211, and the remaining ink is adjusted to a relatively low pressure by the second pressure adjustment mechanism 232L and flows into the common recovery flow path 212.

[0029] The liquid ejection unit 300 is provided with a common supply flow path 211, a common recovery flow path 212, and a plurality of recording element substrates 10. Each recording element substrate 10 is provided with an individual supply flow path 213a communicating with the common supply flow path 211, and an individual recovery flow path 213b communicating with the common recovery flow path 212. With this flow path configuration, a flow (arrow in FIG. 2) occurs in the liquid ejection unit 300 in which ink flows from the common supply flow path 211 through the internal flow path of the recording element substrate 10 to the common recovery flow path 212. A first pressure adjustment mechanism 232H is connected to the common supply flow path 211, and a second pressure adjustment mechanism 232L is connected to the common recovery flow path 212. These pressure adjustment mechanisms 232 generate a pressure difference between the common supply flow path 211 and the common recovery flow path 212, so that a flow of ink occurs from the common supply flow path 211 to the common recovery flow path 212. During a printing operation, a part of the ink that has flowed into the common supply flow path 211 is ejected from the ejection ports formed in the printing element substrate 10 , and the remaining ink flows into the common recovery flow path 212 .

[0030] With the above-mentioned configuration, in the liquid ejection unit 300, while ink flows through the common supply flow path 211 and the common recovery flow path 212, a flow occurs in which a part of the ink passes through each recording element substrate 10. By the ink flowing from the common supply flow path 211 to the common recovery flow path 212 via the recording element substrate 10, heat generated in the recording element substrate 10 can be discharged to the outside of the recording element substrate 10. Furthermore, with such a configuration, when recording is being performed by the liquid ejection head 3, ink flow can be generated even in ejection ports and pressure chambers that are not performing recording, so that thickening and solidification of the ink in those areas can be suppressed. Furthermore, thickened ink and foreign matter in the ink can be discharged to the common recovery flow path 212. That is, with the liquid ejection head 3 of this embodiment, deterioration of image quality can be suppressed, and high-speed, high-image-quality recording is possible.

[0031] It should be noted that the two pressure adjustment mechanisms 232 arranged in the negative pressure control unit 230 described above do not necessarily need to control the pressure to a negative pressure, but it is preferable to control the pressure to a pressure that maintains a negative pressure at the ejection port of the recording element substrate 10. In order to control the pressure value of the ejection port more accurately, it is necessary to suppress pressure fluctuations in the flow path from the pressure adjustment mechanism 232 to the ejection port, so it is preferable that the pressure adjustment mechanism 232 is arranged in a position close to the ejection port. Therefore, for accurate pressure control, it is more preferable that the negative pressure control unit 230 is mounted on the liquid ejection head 3 as in this embodiment.

[0032] 2 constitute a pressure control assembly. To achieve high-quality printing, it is necessary to maintain the pressure difference by suppressing fluctuations in pressure loss that occur in the flow path from the two pressure adjustment mechanisms 232 to the ejection port, and to stabilize the circulating flow rate through the ejection port. For this reason, it is preferable to mount the negative pressure control unit 230 on the liquid ejection head 3, shorten the length of the flow path from the pressure adjustment mechanism 232 to the ejection port, and reduce the pressure loss.

[0033] In this embodiment, a common filter 221 is provided upstream of the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L. In this configuration, pressure loss can be reduced compared to a configuration in which a filter is provided downstream of each of the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L. Furthermore, since it is possible to prevent the negative pressure of the ink at the ejection openings of the recording element substrate 10 (its absolute value) from becoming excessively large, deterioration in image quality can be suppressed.

[0034] <Liquid ejection head> Next, the configuration of the liquid ejection head 3 according to this embodiment will be described. Figures 3(a) and 3(b) are perspective views of the liquid ejection head 3 according to this embodiment. Figure 3(a) shows the liquid ejection head 3 as viewed from below where the recording element substrate 10 is provided, and Figure 3(b) shows the liquid ejection head 3 as viewed from above. The liquid ejection head 3 is a line-type liquid ejection head in which 17 recording element substrates 10 are linearly arranged (arranged inline).

[0035] The liquid ejection head 3 includes a plurality of flexible wiring boards 40 and an electric wiring board 90. As shown in Fig. 3(a), the liquid ejection head 3 is provided with the same number of flexible wiring boards 40 as the recording element substrates 10, and one flexible wiring board 40 is connected to one recording element substrate 10.

[0036] The liquid ejection head 3 is provided with a signal input terminal 91 and a power supply terminal 92 electrically connected to each recording element substrate 10 via the flexible wiring substrate 40 and the electric wiring substrate 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to a control unit of the recording device 1000. The signal input terminal 91 supplies an ejection drive signal to the recording element substrate 10, and the power supply terminal 92 supplies the recording element substrate 10 with power required for ink ejection. By consolidating the wiring using an electric circuit in the electric wiring substrate 90, the number of signal input terminals 91 and power supply terminals 92 can be made smaller than the number of recording element substrates 10. With this configuration, the number of electrical connections to be connected and disconnected when assembling or replacing the liquid ejection head 3 to the recording device 1000 is reduced, improving work efficiency.

[0037] 3(b), liquid connection part 111 provided at one end of liquid ejection head 3 in the longitudinal direction and liquid connection part 112 provided at the other end are connected to a liquid supply system of recording apparatus 1000. With this configuration, ink of four colors, CMYK, is supplied from the supply system of recording apparatus 1000 to liquid ejection head 3, and ink that has passed through liquid ejection head 3 is collected into the supply system of recording apparatus 1000. In this way, ink of each color can circulate via the ink flow path of recording apparatus 1000 and the ink flow path of liquid ejection head 3.

[0038] 4 is an exploded perspective view of the liquid ejection head 3, and shows the parts and units that constitute the liquid ejection head 3. In this embodiment, a liquid ejection unit 300, a liquid supply unit 220, and an electric wiring board 90 are attached to a housing 80.

[0039] The liquid supply unit 220 is composed of a filter box 222 having a filter 221 provided therein, and an ink connector 223. A negative pressure control unit 230 is attached to the filter box 222, and ink that has passed through the filter 221 is supplied from the filter box 222 to the negative pressure control unit 230. The filter box 222 and the ink connector 223 are attached to the housing 80 with the joint rubber 100 sandwiched between them.

[0040] The negative pressure control unit 230 is a unit including a pressure adjustment valve. The negative pressure control unit 230 greatly attenuates pressure loss changes in the supply system of the recording device 1000 (the supply system upstream of the liquid ejection head 3) that occur with fluctuations in the liquid flow rate, by the action of valves and spring members provided inside the negative pressure control unit 230. The negative pressure control unit 230 can stabilize negative pressure changes downstream of the negative pressure control unit 230 (the liquid ejection unit 300 side) within a certain range.

[0041] A first pressure adjustment mechanism 232H and a second pressure adjustment mechanism 232L are built into the negative pressure control unit 230 for each color, and each pressure adjustment mechanism 232 includes a pressure adjustment valve. The first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L are set to different control pressures. The first pressure adjustment mechanism 232H on the high pressure side is connected to a common supply flow path 211 in the liquid discharge unit 300 via the liquid supply unit 220. The second pressure adjustment mechanism 232L on the low pressure side is connected to a common recovery flow path 212 in the liquid discharge unit 300 via the liquid supply unit 220.

[0042] The housing 80 supports the liquid ejection unit 300 and the electric wiring board 90, and also plays a role in ensuring the rigidity of the liquid ejection head 3. The housing 80 is composed of a liquid ejection unit support part 81 and an electric wiring board support part 82. The electric wiring board support part 82 is a support part that supports the electric wiring board 90, and is fixed to the liquid ejection unit support part 81 by screwing. Fig. 4 shows how the liquid ejection unit support part 81 and the electric wiring board support part 82 are separated.

[0043] The liquid ejection unit support part 81 has a role of correcting warping and deformation of the liquid ejection unit 300 to ensure the relative positional accuracy of the multiple recording element substrates 10, and suppresses streaks and unevenness in the recorded material. For this reason, the liquid ejection unit support part 81 preferably has sufficient rigidity, and is preferably made of a metal material such as SUS or aluminum, or a ceramic such as alumina. The liquid ejection unit support part 81 is provided with openings 83 and 84 into which the joint rubber 100 is inserted. Ink supplied from the liquid supply unit 220 is led to the second flow path member 60 constituting the liquid ejection unit 300 via the joint rubber 100.

[0044] The electrical wiring board 90 is provided with a plurality of connection terminals 93, and is electrically connected to the discharge module 200 including the flexible wiring board 40. In this embodiment, one connection terminal 93 is provided for each discharge module 200.

[0045] The liquid ejection unit 300 is composed of a plurality of ejection modules 200 and a flow path member 210, and a cover member 130 is attached to the surface of the liquid ejection unit 300 on the recording medium side. As shown in FIG. 4, the cover member 130 is a member having a frame-shaped surface in which a long opening 131 is provided in the longitudinal direction of the liquid ejection head 3. When the liquid ejection unit 300 is assembled, the recording element substrate 10 and the sealant 110 (see FIG. 9) included in the ejection module 200 are exposed from the opening 131. The frame portion around the opening 131 functions as a contact surface of a cap member that caps the liquid ejection head 3 during standby for recording. The liquid ejection head 3 is preferably configured such that an adhesive, sealant, filler, or the like is applied along the periphery of the opening 131 to fill unevenness and gaps on the ejection port surface of the liquid ejection unit 300, thereby forming a closed space when capped.

[0046] Next, the configuration of the flow path member 210 included in the liquid ejection unit 300 will be described. The flow path member 210 is formed by laminating a first flow path member 50 and a second flow path member 60. A plurality of ejection modules 200 are joined to the joining surface of the first flow path member 50 with an adhesive. The flow paths formed inside the flow path member 210 are configured to distribute ink supplied from the liquid supply unit 220 to each ejection module 200, and return ink circulating from the ejection modules 200 to the liquid supply unit 220. The flow path member 210 is fixed to the liquid ejection unit support part 81 by screwing.

[0047] 5(a) to (c) are explanatory diagrams of the flow path member 210, showing detailed configurations of the first flow path member 50 and the second flow path member 60 that constitute the flow path member 210. FIG. 5(a) shows the front surface (contact surface with the recording element substrate 10) of the first flow path member 50. FIG. 5(b) shows the back surface (contact surface with the second flow path member 60) of the first flow path member 50. FIG. 5(c) shows the back surface (contact surface with the first flow path member 50) of the second flow path member 60.

[0048] A plurality of communication ports 51 are arranged on the surface of the first flow path member 50. The communication ports 51 are regularly arranged in the longitudinal direction of the liquid ejection head 3. A group of communication ports 51 constituting a repeating pattern of the communication ports 51 corresponds to one recording element substrate 10. The communication port 51 is an opening that fluidly connects to the recording element substrate 10, and is a component of the individual supply flow paths 213a and the individual recovery flow paths 213b.

[0049] The second flow path member 60 is formed with a common flow path groove extending in the longitudinal direction of the liquid ejection head 3, and common communication ports 61 that are located at both ends of the second flow path member 60 and communicate with the common flow path groove. The common communication ports 61 are formed in the bottom surface of the common flow path groove, and are fluidly connected to the liquid supply unit 220.

[0050] 6(a) and (b) are explanatory diagrams of the flow paths formed inside the flow path member 210. Fig. 6(a) shows the flow path structure when the flow path member 210 is viewed in the opening direction of the communication port 51. Fig. 6(b) is a cross-sectional view taken along line AA in Fig. 6(a), and shows the flow path structure when the flow path member 210 is viewed in a direction perpendicular to the opening direction of the communication port 51.

[0051] A common supply flow path 211 and a common recovery flow path 212 extend in the longitudinal direction inside the first flow path member 50. In Fig. 6(a), the relative positions of the common supply flow path 211 and the common recovery flow path 212 with respect to the recording element substrate 10 are indicated by dotted lines. The common supply flow path 211 and the common recovery flow path 212 are fluidly connected to the opening 21 of the recording element substrate 10 via the communication port 51 of the first flow path member 50 and the communication port 31 of the support member 30. The support member 30 is a component of the discharge module 200, and will be described in detail later.

[0052] As described above, the common supply flow path 211 is connected to the first pressure adjustment mechanism 232H, which has a relatively high set pressure, and the common recovery flow path 212 is connected to the second pressure adjustment mechanism 232L, which has a relatively low set pressure. In this embodiment, the ink supply path for supplying ink to the recording element substrate 10 is composed of the individual supply flow paths 213a including the common communication port 61, the common supply flow path 211, and the communication port 51. The pressure of the ink passing through the ink supply path is adjusted mainly by the first pressure adjustment mechanism 232H. On the other hand, the ink recovery path for recovering ink from the recording element substrate 10 is composed of the individual recovery flow paths 213b including the communication port 51, the common recovery flow path 212, and the common communication port 61. The pressure of the ink passing through the ink recovery path is adjusted mainly by the second pressure adjustment mechanism 232L. When the discharge operation according to the discharge data is performed in the recording element substrate 10, the ink that is not consumed by the discharge operation among the ink supplied through the ink supply path is recovered to the ink recovery path and circulated.

[0053] <Discharge module> Next, a detailed configuration of the discharge module 200 will be described. Figures 7(a) and (b) are explanatory diagrams of the discharge module 200. Figure 7(a) is a perspective view of the discharge module 200 in an assembled state, and Figure 7(b) is an exploded perspective view of the discharge module 200. The discharge module 200 is composed of a recording element substrate 10, a support member 30 that supports the recording element substrate 10, and a flexible wiring substrate 40 for electrically connecting the recording element substrate 10 to an electric wiring substrate 90.

[0054] The recording element substrate 10 is provided with a terminal 16. A terminal 41 electrically connected to the terminal 16 is provided at one end of the flexible wiring substrate 40, and a terminal 42 electrically connected to a connection terminal 93 (see FIG. 4) of the electric wiring substrate 90 is provided at the other end.

[0055] A method for manufacturing the discharge module 200 will be described. First, the recording element substrate 10 and the flexible wiring substrate 40 are bonded onto the support member 30. Then, the end of the recording element substrate 10 is The terminal 16 and a terminal 41 on the flexible wiring board 40 are electrically connected by wire bonding, and the wire bonding portion (electrical connection portion) is covered and sealed with a sealing material 110. A terminal 42 provided on the end portion opposite to the end portion connected to the terminal 41 and the recording element substrate 10 of the flexible wiring board 40 is electrically connected to a connection terminal 93 of the electrical wiring board 90.

[0056] The support member 30 is a support body that supports the recording element substrate 10 and also a flow path member that fluidly connects the recording element substrate 10 and the flow path member 210, and therefore it is preferable that the support member 30 has a high degree of flatness and can be joined to the recording element substrate 10 with sufficiently high reliability. Therefore, the material of the support member 30 is preferably, for example, alumina or a resin material.

[0057] <Printing element substrate> Next, the detailed configuration of the recording element substrate 10 will be described. FIGS. 8(a) to (c) are explanatory diagrams of the recording element substrate 10 according to this embodiment. FIG. 8(a) shows the surface of the recording element substrate 10 on which the ejection ports 13 are formed. FIG. 8(b) is an enlarged view of part B shown in FIG. 8(a). FIG. 8(c) shows the reverse side of the surface shown in FIG. 8(a). Note that the configuration of the recording element substrate 10 shown in FIGS. 8(a) to (c) is one of the configuration examples. In applying the present invention, for example, the number of ejection port arrays formed in the ejection port forming member 12 of the recording element substrate 10 may be more or less than the number shown in FIG. 8(a). In the following description, the direction in which the ejection port array in which the multiple ejection ports 13 are linearly arranged extends is referred to as the "ejection port array direction".

[0058] 8(b), recording elements 15, which are heat generating elements (energy generating elements) for generating thermal energy to bubble ink, are disposed at positions corresponding to the ejection ports 13. In the recording element substrate 10, a plurality of pressure chambers 23, each including a recording element 15 therein, are partitioned by partition walls 22.

[0059] The recording elements 15 are electrically connected to the terminals 16 by electrical wiring provided on the recording element substrate 10. The recording elements 15 generate heat and boil the ink based on a pulse signal input from a control circuit of the recording device 1000 via an electrical wiring substrate 90 (see FIG. 5) and a flexible wiring substrate 40. The recording element substrate 10 ejects ink from the ejection ports 13 by utilizing the force of bubbles generated by this boiling.

[0060] 8(b), a supply path 18 and a recovery path 19 extend along each ejection port array on the recording element substrate 10. The supply path 18 and the recovery path 19 are arranged to sandwich the ejection port array between them, and are flow paths extending in the ejection port array direction. The supply path 18 communicates with the ejection port 13 (pressure chamber 23) via the supply port 17a, and the recovery path 19 communicates with the ejection port 13 (pressure chamber 23) via the recovery port 17b.

[0061] As shown in Fig. 8(c), a sheet-like cover plate 20 is laminated on the back surface (the surface opposite to the surface on which the ejection ports 13 are formed) of the recording element substrate 10. The cover plate 20, which is a lid member, is provided with a plurality of openings 21 that communicate with the supply paths 18 and the recovery paths 19. In this embodiment, the cover plate 20 is provided with three openings 21 for one supply path 18 and two openings 21 for one recovery path 19, but the number of openings is not limited to this when applying the present invention. Each of the openings 21 of the cover plate 20 communicates with one of the plurality of communication ports 51 shown in Fig. 6(a).

[0062] It is preferable that the cover plate 20 has sufficient corrosion resistance against ink. Also, from the viewpoint of preventing color mixing, high precision is required for the shape and position of the opening 21. Therefore, it is preferable to use a photosensitive resin material or a silicon plate as the material for the cover plate 20 and to provide the opening 21 by a photolithography process.

[0063] Next, the flow of ink in the recording element substrate 10 will be described with reference to Fig. 9. Fig. 9 is a perspective view showing a cross section (cross section CC in Fig. 8(a)) of the recording element substrate 10, and shows the flow path configuration of the recording element substrate 10. The cover plate 20 functions as a lid that forms part of the walls of the supply path 18 and the recovery path 19 formed in the substrate 11 of the recording element substrate 10.

[0064] The recording element substrate 10 is constructed by laminating a substrate 11 made of Si and a discharge port forming member 12 made of a photosensitive resin. A cover plate 20 is bonded to the rear surface of the substrate 11 (the surface opposite to the surface connected to the discharge port forming member 12). Recording elements 15 are formed on the surface of the substrate 11 facing the discharge port forming member 12. Grooves that form a supply path 18 and a recovery path 19 extending along the discharge port array are formed on the surface of the substrate 11 facing the cover plate 20.

[0065] Of the supply path 18 and recovery path 19 formed by the substrate 11 and the cover plate 20, the former is connected to a common supply path 211 in a path member 210, and the latter is connected to a common recovery path 212 in the path member 210. As described above, the first pressure adjustment mechanism 232H is connected to the common supply path 211, and the second pressure adjustment mechanism 232L is connected to the common recovery path 212, so that a pressure difference occurs between the supply path 18 and the recovery path 19.

[0066] When a pressure difference occurs and ink is ejected from the ejection ports 13 to perform recording, in the flow paths corresponding to the ejection ports 13 for which no ejection operation is being performed, the ink in the supply path 18 flows to the recovery path 19 via the supply port 17a, the pressure chamber 23, and the recovery port 17b. In FIG. 9, the ink flow direction is indicated by arrow D. In this way, by configuring the ink to flow even in the flow paths corresponding to the ejection ports 13 for which no ejection operation is being performed, thickened ink, bubbles, foreign matter, and the like that are generated by evaporation from the ejection ports 13 can be recovered to the recovery path 19. Also, it is possible to suppress the ink in the ejection ports 13 and the pressure chambers 23 from becoming thicker and the concentration of the coloring material from increasing.

[0067] The ink recovered to the recovery channel 19 passes through the opening 21 of the cover plate 20 , the communication port 31 of the support member 30 , the communication port 51 of the first channel member 50 , and the common recovery channel 212 in this order, and is then recovered to the ink path of the recording device 1000 .

[0068] <Pressure adjustment mechanism> Next, the pressure adjustment mechanism 232 will be described in detail. Fig. 10(a) to (d) are diagrams showing the structure of the pressure adjustment mechanism 232 according to this embodiment. Fig. 10(a) is a perspective view showing the appearance of the pressure adjustment mechanism 232. Fig. 10(b) is a plan view showing the appearance of the pressure adjustment mechanism 232. Fig. 10(c) and Fig. 10(d) are E-E cross-sectional views of Fig. 10(b). Fig. 10(c) shows a state in which the movable valve 2325 is closed and pressure adjustment is not performed by the pressure reducing valve. Fig. 10(d) shows a state in which the movable valve 2325 is open and pressure control is performed by the pressure reducing valve. The operating principle of the pressure adjustment mechanism 232 is similar to that of what is generally called a "pressure reducing regulator."

[0069] The pressure adjustment mechanism 232 is a pressure reducing valve that reduces and adjusts the pressure of the ink that has flowed inside. A pressure chamber 2323, an orifice 2320, and a liquid circulation chamber 2324 that communicates with the orifice 2320 are formed inside a housing 231 of the pressure adjustment mechanism 232. The pressure adjustment mechanism 232 includes a pressure receiving plate 2321 that functions as a pressure receiving portion, a flexible film 2322 that fluidly seals the pressure receiving plate 2321 and the housing 231, a movable valve 2325 that opens and closes the orifice 2320, a spring 2326, and a spring 2330. The orifice 2320 is located upstream of the pressure chamber 2323 in the ink flow direction, and is configured to be openable and closable by the movable valve 2325 that is a valve body.

[0070] The movable valve 2325 is configured to be rotatable (swingable) around a rotation shaft 2327. It is a lever member. The rotating shaft 2327 extends in a direction perpendicular to the plane of the paper in Fig. 10(c), and the movable valve 2325 is configured to be rotatable in a clockwise direction and a counterclockwise direction in Fig. 10(c). The movable valve 2325 is biased by a spring 2330 in a direction moving from a position where the orifice 2320 is opened to a position where the orifice 2320 is closed (downward in Fig. 10(c)).

[0071] The movable valve 2325 is provided with a closing portion 2328 that closes the gap with the orifice 2320 on one end side in a direction perpendicular to the axial direction of the rotating shaft 2327, and a contact portion 2329 with the pressure-receiving plate 2321 on the other end side. The rotating shaft 2327 is located between the closing portion 2328 and the contact portion 2329, and is supported by the housing 231. The contact portion 2329 is arranged so as to be able to come into contact with the pressure-receiving plate 2321 inside the pressure chamber 2323. The movable valve 2325 is provided downstream of the orifice 2320 in the ink flow direction, and opens and closes the orifice 2320.

[0072] The pressure-receiving plate 2321 is configured to be movable by the pressure difference between the pressure chamber 2323 and the outside of the housing 231. The pressure-receiving plate 2321 is biased by a spring 2326 in a direction (upward in FIG. 10(c)) away from the contact portion 2329 of the movable valve 2325. In this embodiment, the biasing direction of the spring 2326 and the biasing direction of the spring 2330 are opposite to each other. Due to these biasing members, under normal circumstances, as shown in FIG. 10(c), the movable valve 2325 abuts against a portion of the housing 231 near the orifice 2320, blocking the gap between the movable valve 2325 and the housing 231, and the orifice 2320 is in a closed state.

[0073] When the pressure-receiving plate 2321 moves in a direction approaching the movable valve 2325 (downward in FIG. 10(c)) so as to reduce the volume of the pressure chamber 2323, it comes into contact with the contact portion 2329 of the movable valve 2325. When the pressure-receiving plate 2321 continues to move further, the movable valve 2325 rotates around the rotating shaft 2327, with the contact point between the pressure-receiving plate 2321 and the contact portion 2329 as the force point and the contact point between the rotating shaft 2327 and the housing 231 as the fulcrum. Then, the movable valve 2325 moves against the biasing force of the spring 2330, and a gap is generated between the orifice 2320 and the movable valve 2325. Conversely, when the pressure plate 2321 moves away from the movable valve 2325 and the biasing force of the spring 2330 exceeds the force due to the pressure difference between the upstream and downstream sides of the orifice 2320, the movable valve 2325 rotates in the opposite direction to close the gap. In this way, the movable valve 2325 is configured to be able to open and close the orifice 2320 in conjunction with the operation of the pressure plate 2321.

[0074] The direction in which the pressure plate 2321 presses the rotating shaft 2327 when the movable valve 2325 is opened is substantially opposite to the direction in which the spring 2326 urges the pressure plate 2321. In Fig. 10(d), the distance from the fulcrum to the point of force in the direction perpendicular to the pressing direction of the pressure plate 2321 is shown as L1, and the distance from the fulcrum to the valve center is shown as L2. The valve center is the center of the cross section of the orifice 2320.

[0075] Ink flowing in from the upstream side of the pressure adjustment mechanism 232 flows into the pressure chamber 2323 through the gap between the movable valve 2325 and the orifice 2320, and transmits its pressure to the pressure-receiving plate 2321. After that, the ink flows out from the downstream side of the pressure adjustment mechanism 232.

[0076] In the pressure adjustment mechanism 232 of this embodiment, the pressure inside the pressure chamber 2323 is determined by the following relational expression which indicates the balance of forces applied to each part. The principle of leverage is applied to balance the forces. (k d x d +P2S d )*L1=(-k v x v +(P1-P2)*S v )*L2...(Formula 1) L1: The distance from the fulcrum to the force point in the direction perpendicular to the pressing direction of the pressure plate 2321 L2: The distance from the fulcrum to the center of the valve in a direction perpendicular to the pressing direction of the pressure plate 2321 P1: Ink pressure on the upstream side of the orifice 2320 (liquid flow chamber 2324) (pressure difference with atmospheric pressure) P2: Ink pressure in the pressure chamber 2323 (pressure difference with atmospheric pressure) k d : Spring constant of the spring 2326 that biases the pressure plate 2321 x d : Spring displacement of the spring 2326 that biases the pressure plate 2321 k v : Spring constant of the spring 2330 that biases the movable valve 2325 x v : Spring displacement of the spring 2330 that biases the movable valve 2325 S d : Pressure receiving area of ​​the pressure receiving part (pressure receiving plate 2321 and flexible film 2322) S v : Pressure receiving area of ​​movable valve 2325

[0077] Moreover, by rearranging (Equation 1), the ink pressure P2 can be expressed by the following (Equation 2). P2=(-k d x dL1-k v x v L2+P1S v L2) / (S d L1+S v L2)...(Formula 2)

[0078] From the above (Equation 2), it can be seen that ink pressure P2 can be set to a desired control pressure by changing the spring force of spring 2326 and spring 2330, which are the biasing members.

[0079] Furthermore, if the valve resistance is R and the flow rate passing through the orifice 2320 is Q, then the following equation 3 holds: P2=P1-QR...(Formula 3)

[0080] In this embodiment, the orifice 2320 and the movable valve 2325 are configured so that the valve resistance R and the valve opening are inversely proportional to each other. That is, when the valve opening increases and the flow rate Q passing through the orifice 2320 increases, the valve resistance R decreases. FIG. 11 is a graph showing an example of the relationship between the valve resistance R and the valve opening. In the graph of FIG. 11, the vertical axis is the valve resistance R [Pa·min / ml / cp] and the horizontal axis is the valve opening [mm]. The ink pressure P2 is determined by determining the valve position so that (Equation 2) and (Equation 3) are satisfied simultaneously.

[0081] As described above, the negative pressure control unit 230 of this embodiment includes two pressure adjustment mechanisms 232, each with a different control pressure. The ink outlet of the first pressure adjustment mechanism 232H, whose control pressure is set to a relatively high pressure, is connected to the common supply flow path 211, and the ink outlet of the second pressure adjustment mechanism 232L, whose control pressure is set to a relatively low pressure, is connected to the common recovery flow path 212. In this configuration, in order to suppress settling of ink containing a large amount of solid content such as pigments and to achieve high-quality printing, it is preferable that the flow rate from the common supply flow path 211 to the common recovery flow path 212 is large.

[0082] In order to increase the flow rate, it is preferable that the difference between the ink pressure in the common supply flow path 211 and the ink pressure in the common recovery flow path 212 is large, that is, the difference between the control pressure of the first pressure adjustment mechanism 232H and the control pressure of the second pressure adjustment mechanism 232L is large. It is preferable that the pressure difference between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L is, for example, 2000 [Pa] or more. In this embodiment, the negative pressure control unit 230 is configured to obtain a desired pressure difference by changing the spring force or the like between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L.

[0083] When the pressure difference is 2000 [Pa], if the flow path resistance inside the recording element substrate 10 is 100 [Pa·min / ml / cP], it becomes possible to flow 2 [cP] ink at 10 [ml / min], and sedimentation can be suppressed. Note that the flow path resistance inside the recording element substrate 10 is the total flow path resistance of the supply path 18, supply port 17a, recovery port 17b, and recovery path 19 shown in FIG. 9.

[0084] To achieve even higher quality printing, it is advisable to stabilize the amount of ink ejected. If the negative pressure at the ejection port 13 becomes excessively large, the amount of ink ejected may become unstable. Therefore, in order to stabilize the amount of ink ejected, it is preferable to set the negative pressure at the ejection port 13 to -5000 [Pa] or more (absolute value 5000 or less).

[0085] The ink pressure at the ejection port 13 is approximately the average value of the ink pressures in the common supply flow path 211 and the common recovery flow path 212. As described above, it is preferable that the pressure difference between the common supply flow path 211 and the common recovery flow path 212 is large, but if the negative pressure of the common recovery flow path 212, which is controlled to the low pressure side, is increased in order to increase the pressure difference, the negative pressure at the ejection port 13 may become excessively large. Therefore, in this embodiment, the negative pressure control unit 230 is configured to control the ink pressure in the supply path 18 and the supply port 17a of the recording element substrate 10 that supply ink to the ejection port 13 (pressure chamber 23) to a positive pressure.

[0086] In this embodiment, the first pressure adjustment mechanism 232H, which controls the pressure of ink flowing through the supply path 18 and the supply port 17a, is disposed above the ejection port 13. Figure 12 is a side view of the liquid ejection head 3 according to this embodiment, and shows the positional relationship between the first pressure adjustment mechanism 232H and the ejection port 13.

[0087] In this embodiment, the liquid ejection head 3 is configured so that the height difference between the center of the first orifice 2320H of the first pressure adjustment mechanism 232H and the surface on which the ejection port 13 of the recording element substrate 10 is formed is 30 [mm] in the gravity direction. With this configuration, the ink pressure increases before flowing from the first pressure adjustment mechanism 232H to the ejection port 13 due to the height difference between the first pressure adjustment mechanism 232H and the ejection port 13. Specifically, if the pressure control value of the first pressure adjustment mechanism 232H is -200 [Pa] and the specific gravity of the ink is 1 [g / cm^3], the ink pressure in the supply path 18 and the supply port 17a can be controlled to a positive pressure of approximately +100 [Pa] by providing a height difference of 30 [mm].

[0088] As described above, according to the configuration of this embodiment, the negative pressure control unit 230 controls the ink in the supply path 18 to a positive pressure and controls the ink in the recovery path 19 to a negative pressure, thereby preventing the negative pressure of the ink in the ejection port 13 of the recording element substrate 10 from becoming excessively large. Furthermore, in this embodiment, the filter 221 is provided upstream of the negative pressure control unit 230, and no filter is provided between the negative pressure control unit 230 and the liquid ejection unit 300, so that pressure loss can be reduced and the negative pressure of the ink in the ejection port 13 can be prevented from becoming excessively large. Therefore, according to the configuration of this embodiment, the flow rate of the ink flowing from the common supply flow path 211 to the common recovery flow path 212 can be increased while preventing the negative pressure of the ejection port 13 from becoming excessively large. In addition, since the ink ejection amount can be stabilized while preventing the ink from settling, etc., deterioration of image quality can be prevented.

[0089] This embodiment is particularly suitable for the case where high-performance ink is used for the purpose of improving image quality and is prone to thickening, adhesion, and sedimentation. Examples of inks prone to thickening, adhesion, and sedimentation include inks containing titanium oxide or hollow particles, inks with a viscosity of 3 cp or more, inks with a water content of 50% or more, etc.

[0090] In the above embodiment, the negative pressure control unit 230 is configured by the pressure adjustment mechanism 232 which is a negative pressure adjustment mechanism, but the application of the present invention is not limited to this configuration. For example, of the two pressure adjustment mechanisms 232, the first pressure adjustment mechanism 232H, whose control pressure is set to a relatively high pressure, may be used as a positive pressure adjustment mechanism to control the ink pressure at the outlet of the first pressure adjustment mechanism 232H to a positive pressure.

[0091] Moreover, the two pressure adjustment mechanisms 232 may be disposed facing each other in one housing. Fig. 13 is a diagram showing a configuration example of the negative pressure control unit 230. As shown in Fig. 13, in the following description, the reference numerals of the components of the first pressure adjustment mechanism 232H are followed by a suffix H, and the reference numerals of the components of the second pressure adjustment mechanism 232L are followed by a suffix L, and the components are described separately as necessary.

[0092] In the configuration example shown in Fig. 13, the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L are arranged point-symmetrically to each other. With such an arrangement, the two pressure adjustment mechanisms 232 are arranged in one housing to form an integrated unit, thereby realizing space saving. In this case, the same ink may be flowed through the two pressure adjustment mechanisms 232, or they may be controlled to different pressures. When controlling to different pressures, one of the two pressure adjustment mechanisms 232 is fluidly connected to the upstream side of the ejection nozzle and the other is fluidly connected to the downstream side, thereby circulating the ink in the ejection nozzle and preventing the ink from sticking in the ejection nozzle.

[0093] In the above embodiment, the pressure adjustment mechanism 232 is provided with a coupled spring constituted by the springs 2326 and 2330 as the biasing means, but the application of the present invention is not limited to this configuration. If the biasing force of one spring is sufficient to control the ink pressure to a desired negative pressure in the pressure adjustment mechanism 232, the configuration may be such that only one of the springs 2326 and 2330 is provided.

[0094] [Example of negative pressure control unit configuration] In the above-described embodiment, different control pressures are set for the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L of the negative pressure control unit 230. Hereinafter, a specific configuration for generating a pressure difference between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L will be described by way of example.

[0095] <First configuration example> First, a first configuration example in which a pressure difference is generated by utilizing a head difference will be described. FIG. 14 is an explanatory diagram of the negative pressure control unit 230 of the first configuration example. In the first configuration example, the first orifice 2320H of the first pressure adjustment mechanism 232H and the second orifice 2320L of the second pressure adjustment mechanism 232L are arranged to be shifted in the direction of gravity. With this configuration, a difference 235 is generated between the distance in the direction of gravity between the first orifice 2320H of the first pressure adjustment mechanism 232H and the discharge port 13 and the distance in the direction of gravity between the second orifice 2320L of the second pressure adjustment mechanism 232L and the discharge port 13. In the first configuration example, the first pressure adjustment mechanism 232H is arranged above the second pressure adjustment mechanism 232L. The value of the difference 235 can be appropriately determined according to the pressure difference to be generated.

[0096] In the first configuration example, a more accurate pressure difference can be generated by the difference 235, and the factors that cause fluctuations in the pressure difference can be reduced. This configuration is particularly suitable when there is ample space in the gravity direction of the liquid ejection head 3 and the recording apparatus 1000, and it is desired to accurately control the pressure difference.

[0097] <Second configuration example> Next, a second configuration example will be described in which a pressure difference is generated by changing the spring constant in each pressure adjustment mechanism 232. FIG. 15 is an explanatory diagram of a negative pressure control unit 230 of the second configuration example. In the second configuration example, the spring constant k d and the spring constant k of the spring 2330L of the second pressure adjustment mechanism 232L. d and are set to different values.

[0098] As shown in the above (Equation 2), the spring constant k d The pressure plate 2321 changes The biasing force changes, and the ink pressure P2 changes. Therefore, in the second configuration example, the spring constant k d By making a difference between the biasing force of the spring (first biasing member) 2326H biasing the first movable valve 2325H and the biasing force of the spring (second biasing member) 2326L biasing the second movable valve 2325L, a pressure difference can be generated. Also, with such a configuration, all parts other than the spring 2330 can be used in common between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L.

[0099] A specific example is shown below. In (Equation 2), the ink pressure P2 (pressure difference with respect to atmospheric pressure) in the pressure chamber 2323 is set to -3000 [Pa], and the spring constant k d Let the spring constant k d1 Then, the following (Equation 4) holds. -3000=(-k d1 x d L1-k v x v L2+P1S v L2) / (S d L1+S v L2)...(Formula 4)

[0100] Rearranging (Equation 4), k d1 is expressed as follows (Equation 5). k d1 =-(-3000(Sd L1+S v L2)+k v x v L2-P1S v L2) / x d L1...(Formula 5)

[0101] On the other hand, the ink pressure P2 (pressure difference with respect to atmospheric pressure) in the pressure chamber 2323 is set to -5000 [Pa], and the spring constant k d Let the spring constant k d2 Then, k d2 is expressed as follows (Equation 6). k d2 =-(-5000(S d L1+S v L2)+k v x v L2-P1S v L2) / x d L1...(Formula 6)

[0102] From the above, the spring constant k is expressed as (Equation 5) and (Equation 6). d By changing the spring constant k , the ink pressure P2 of each pressure adjustment mechanism 232 can be adjusted. That is, for each of the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L, an appropriate spring constant k according to the control pressure is set. d A desired pressure difference can be generated by using the spring 2330. For example, the spring constant k is set so that the biasing force of the spring 2326H of the first pressure adjustment mechanism 232H, which has a relatively high control pressure, is smaller than the biasing force of the spring 2326L of the second pressure adjustment mechanism 232L, which has a relatively low control pressure. d It is preferable to select

[0103] In the second configuration example, the spring constant k d The spring constant k of spring 2326 was set to v There may be a difference between the spring constant k d and the spring constant k vIn addition, as a method for changing the spring constant, for example, a spring with a different number of turns or a spring made of a different material may be used, but the method is not particularly limited.

[0104] <Third configuration example> Next, a third configuration example will be described in which a pressure difference is generated by changing the spring storage length in each pressure adjustment mechanism 232. Figures 16(a) and (b) are explanatory diagrams of the negative pressure control unit 230 of the third configuration example. In the third configuration example, the spring storage length of the spring 2326H of the first pressure adjustment mechanism 232H and the spring storage length of the spring 2326L of the second pressure adjustment mechanism 232L are set to different lengths.

[0105] The spring storage length refers to the length from one end of the spring to the other end when the movable valve 2325 is closed. When the same spring is used, a spring with a shorter spring storage length increases the spring displacement and therefore the biasing force of the spring, compared to a configuration with a longer spring storage length.

[0106] FIG. 16(a) shows the structure of a negative pressure control unit 230 and a second pressure adjustment mechanism according to a third configuration example. 232L。 The first pressure adjustment mechanism 232H of the third configuration example is provided with a spring holder 2331H, and one end of the spring 2326H is supported by the spring holder 2331H. Similarly, the second pressure adjustment mechanism 232L is provided with a spring holder 2331L, and one end of the spring 2326L is supported by the spring holder 2331L. That is, the spring storage length of the spring 2326L is equal to the length from the spring support surface of the spring holder 2331 to the spring support surface of the second movable valve 2325L. Similarly, the spring storage length of the spring 2326L is equal to the length from the spring support surface of the spring holder 2331 to the spring support surface of the second movable valve 2325L. The spring storage length of the spring 2330 is equal to the length from the spring support surface of the pressure-receiving plate 2321 to the spring support surface of the housing 231 when the movable valve 2325 is closed.

[0107] In the third configuration example, the spring holders 2331H and 2331L are configured so that the spring storage length 236 in the second pressure adjustment mechanism 232L is different from the spring storage length in the first pressure adjustment mechanism 232H. With this configuration, a difference occurs between the biasing force of the spring (first biasing member) 2326H biasing the first movable valve 2325H and the biasing force of the spring (second biasing member) 2326L biasing the second movable valve 2325L, so that a pressure difference can be generated. With this configuration, accurate pressure control is possible, so that a desired pressure difference can be generated and the ink circulation flow rate in the ejection port can be adjusted with higher accuracy. For example, it is preferable to select the spring storage length so that the biasing force of the spring 2330H of the first pressure adjustment mechanism 232H, which has a relatively high control pressure, is smaller than the biasing force of the spring 2330L of the second pressure adjustment mechanism 232L, which has a relatively low control pressure.

[0108] 16(b) shows an enlarged view of the structure of the negative pressure control unit 230 according to a modified example of the third configuration example and the spring storage part of the second pressure adjustment mechanism 232L. In a configuration in which the spring storage length is changed to generate a pressure difference, it is preferable that the spring holder 2331 is composed of multiple parts and the spring storage length is adjustable.

[0109] In the third configuration example, a difference is provided in the spring storage length of the spring 2326 in the two pressure adjustment mechanisms 232, but a difference may be provided in the spring storage length of the spring 2330, or a difference may be provided in the spring storage lengths of both springs. With this configuration, it becomes possible to adjust the control pressure after assembling the negative pressure control unit 230. In turn, since more accurate pressure control becomes possible, a desired pressure difference can be generated and the ink circulation flow speed in the ejection port can be adjusted with higher precision.

[0110] <Fourth configuration example> Next, the pressure receiving area S of the pressure receiving portion (the pressure receiving plate 2321 and the flexible film 2322) in each pressure adjustment mechanism 232 dA fourth configuration example in which a pressure difference is generated by changing the pressure difference between the first pressure receiving plate 2321H and the second pressure receiving plate 2321L of the second pressure adjustment mechanism 232L is described below. Fig. 17 is an explanatory diagram of the negative pressure control unit 230 of the fourth configuration example. In the fourth configuration example, the diameter 237H of the first pressure receiving plate 2321H of the first pressure adjustment mechanism 232H and the diameter 237L of the second pressure receiving plate 2321L of the second pressure adjustment mechanism 232L are different in length. The first pressure receiving plate 2321H and the second pressure receiving plate 2321L are substantially circular plates, and their respective pressure receiving areas are different from each other.

[0111] As in the fourth configuration example, the diameter 237H of the first pressure receiving plate 2321H and the diameter 237L of the second pressure receiving plate 2321L are changed to change the pressure receiving area S of the pressure receiving portion. d By adjusting the pressure P2 of each pressure adjustment mechanism 232, it is possible to adjust the ink pressure P2 of each pressure adjustment mechanism 232. For example, it is preferable to configure the pressure receiving area of ​​the first pressure receiving plate 2321H of the first pressure adjustment mechanism 232H, which has a relatively high control pressure, to be larger than the pressure receiving area of ​​the second pressure receiving plate 2321L of the second pressure adjustment mechanism 232L, which has a relatively low control pressure. Also, by increasing the pressure receiving area of ​​the pressure receiving plate 2321, it is possible to reduce the influence of fluctuations in the ink pressure P1 applied from the orifice 2320 side.

[0112] In the fourth configuration example, the flexible film 2322 is provided to seal the gap between the pressure-receiving plate 2321 and the housing 231, but the application of the present invention is not limited to this configuration. Any sealing configuration that can fluidly seal and does not interfere with the operation of the pressure-receiving plate 2321 or the opening and closing operation of the movable valve 2325 can be used for the pressure adjustment mechanism 232, not limited to the flexible film 2322.

[0113] <Fifth Configuration Example> Next, the pressure receiving area S of the movable valve 2325 in each pressure adjustment mechanism 232 vA fifth configuration example in which a pressure difference is generated by changing the pressure difference will be described. FIG. 18 is an explanatory diagram of the negative pressure control unit 230 of the fifth configuration example, showing the structure of the negative pressure control unit 230 and an enlarged view of the vicinity of the second orifice 2320L of the second pressure adjustment mechanism 232L. When the movable valve 2325 is closed, the inner part of the contact part between the movable valve 2325 and the housing 231 (the part surrounded by the closed part 2328 of the movable valve 2325) is approximately circular and receives pressure from the liquid circulation chamber 2324 side. Hereinafter, the diameter of the part of the movable valve 2325 that receives pressure from the liquid circulation chamber 2324 side will be described as a pressure receiving diameter 238. In the fifth configuration example, the pressure receiving diameter 238H of the first movable valve 2325H of the first pressure adjustment mechanism 232H and the pressure receiving diameter 238L of the second movable valve 2325L of the second pressure adjustment mechanism 232L are different in length.

[0114] As in the fifth configuration example, the pressure receiving diameter 238H of the first movable valve 2325H and the pressure receiving diameter 238L of the second movable valve 2325L are changed to change the pressure receiving area S v By adjusting the pressure receiving diameter 238 of the movable valve 2325, the ink pressure P2 of each pressure adjustment mechanism 232 can be adjusted. Also, for example, by reducing the pressure receiving diameter 238 of the movable valve 2325, the size of the negative pressure control unit 230 can be reduced. v If the pressure receiving area S becomes too small, the valve resistance is likely to fluctuate due to the inclination of the movable valve 2325, and the control pressure may become unstable. v is preferably set taking into consideration the size of the negative pressure control unit 230 and the stability of the control pressure.

[0115] In the fifth configuration example, the pressure receiving portion of the movable valve 2325 is a substantially circular flat surface, but the application of the present invention is not limited to this configuration. v By changing various dimensions to adjust the pressure P2, the ink pressure P2 of the pressure adjustment mechanism 232 can be adjusted to a desired pressure.

[0116] As shown in the first to fifth configuration examples, by changing the arrangement positions or dimensions of some of the components in the two pressure adjustment mechanisms 232, a difference in the control pressure can be generated. Furthermore, according to the first to fifth configuration examples, since there are many components that can be used in common between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L, the number of components used in the negative pressure control unit 230 can be reduced, which can lead to cost reduction. In particular, in the configuration in which only the spring 2326 is a separate component that is not common between the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L as in the second configuration example, the number of components increases only for the spring 2326, which does not require a mold for molding, so that an increase in costs can be more effectively suppressed.

[0117] The first to fifth configuration examples may be combined rather than used alone. For example, the second and fourth configuration examples may be combined to use dedicated springs 2326 and pressure-receiving plates 2321 for the first pressure adjustment mechanism 232H and the second pressure adjustment mechanism 232L, respectively. By combining the configuration examples, the control range of the ink pressure in each pressure adjustment mechanism 232 can be expanded.

[0118] In the above-described embodiment and configuration examples, the negative pressure control unit 230 is configured with the movable valve 2325, which is a lever valve, but the application of the present invention is not limited to such a configuration. A direct-acting valve 2332 configured to be capable of translation may be provided instead of the valve 2325. FIG. 19 is a diagram showing a pressure adjustment mechanism 232 according to a modified example, and shows the configuration of the pressure adjustment mechanism 232 including the direct-acting valve 2332.

[0119] The disclosure of this embodiment includes the following configuration. (Configuration 1) a recording element substrate having an ejection port, an energy generating element that generates energy for ejecting liquid from the ejection port, a supply path that supplies liquid to the ejection port, and a recovery path that recovers liquid not ejected from the ejection port; a pressure control unit that controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the pressure of the liquid at the discharge port becomes negative; Equipped with The liquid ejection head, wherein the pressure control unit controls the pressure of the liquid in the supply path to a positive pressure, and controls the pressure of the liquid in the recovery path to a negative pressure. (Configuration 2) The liquid ejection head described in configuration 1, wherein the pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the difference between the pressures is 2000 Pa or more. (Configuration 3) 3. The liquid ejection head according to configuration 2, wherein the flow path resistance of the supply path and the recovery path is 100 [Pa·min / ml / cP] or less. (Configuration 4) A liquid ejection head described in any one of configurations 1 to 3, characterized in that the pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the negative pressure of the liquid at the ejection port is -5000 [Pa] or more. (Configuration 5) the pressure control unit includes a first pressure adjustment mechanism that adjusts the pressure of the liquid to a negative pressure and sends the liquid to the supply path, and a second pressure adjustment mechanism that adjusts the pressure of the liquid to a negative pressure and sends the liquid to the recovery path, 5. The liquid ejection head according to any one of configurations 1 to 4, wherein the first pressure adjustment mechanism is located above the ejection port. (Configuration 6) the first pressure adjustment mechanism has an orifice and a movable valve configured to be able to open and close the orifice, 6. The liquid ejection head according to configuration 5, wherein the difference in height between the center of the orifice and the surface on which the ejection port is formed in the direction of gravity is 30 mm or more. (Configuration 7) 7. The liquid ejection head according to configuration 5 or 6, wherein the first pressure adjustment mechanism and the second pressure adjustment mechanism are arranged to be shifted from each other in the direction of gravity. (Configuration 8) the first pressure adjustment mechanism includes a first orifice, a first pressure plate configured to be movable in response to a pressure difference between the inside and the outside of the first pressure adjustment mechanism, and a first movable valve configured to open and close the first orifice in conjunction with the movement of the first pressure plate; A liquid ejection head described in any one of configurations 5 to 7, characterized in that the second pressure adjustment mechanism has a second orifice, a second pressure plate configured to be movable due to the pressure difference between the inside and outside of the second pressure adjustment mechanism, and a second movable valve configured to open and close the second orifice in conjunction with the movement of the second pressure plate. (Configuration 9) the first movable valve is configured to be movable from a position where the first orifice is closed to a position where the first orifice is opened by being pressed by the first pressure plate, The first pressure adjustment mechanism is configured to move the first pressure plate in a direction away from the first movable valve. a first biasing member for biasing the the second movable valve is configured to be movable from a position where the second orifice is closed to a position where the second orifice is opened by being pressed by the second pressure plate, the second pressure adjustment mechanism has a second biasing member that biases the second pressure receiving plate in a direction away from the second movable valve, 9. The liquid ejection head according to configuration 8, wherein the biasing force of the first biasing member is smaller than the biasing force of the second biasing member. (Configuration 10) the first pressure adjustment mechanism has a first biasing member that biases the first movable valve in a direction in which the first movable valve moves from a position at which the first orifice is opened to a position at which the first orifice is closed, the second pressure adjustment mechanism has a second biasing member that biases the second movable valve in a direction in which the second movable valve moves from a position at which the second movable valve opens the second orifice to a position at which the second orifice is closed, 10. The liquid ejection head according to configuration 8 or 9, wherein the biasing force of the first biasing member is smaller than the biasing force of the second biasing member. (Configuration 11) 11. The liquid ejection head according to any one of configurations 8 to 10, wherein a pressure receiving area of ​​the first pressure receiving plate is larger than a pressure receiving area of ​​the second pressure receiving plate. (Configuration 12) A liquid ejection head described in any one of configurations 8 to 11, characterized in that the area of ​​a pressure-receiving portion where the first movable valve receives pressure from the first orifice side is different from the area of ​​a pressure-receiving portion where the second movable valve receives pressure from the second orifice side. (Configuration 13) 13. The liquid ejection head according to any one of configurations 1 to 12, wherein the liquid whose pressure is controlled by the pressure control unit contains titanium oxide or hollow particles. (Configuration 14) 14. The liquid ejection head according to any one of configurations 1 to 13, wherein the viscosity of the liquid, the pressure of which is controlled by the pressure control unit, is 3 [cp] or more. (Configuration 15) 15. The liquid ejection head according to any one of configurations 1 to 14, wherein the water ratio of the liquid whose pressure is controlled by the pressure control unit is 50% or more. (Configuration 16) a liquid ejection head including a recording element substrate having an ejection port, an energy generating element that generates energy for ejecting liquid from the ejection port, a supply path that supplies liquid to the ejection port, and a recovery path that recovers liquid not ejected from the ejection port; a pressure control unit that controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the pressure of the liquid at the discharge port becomes negative; Equipped with The recording apparatus according to claim 1, wherein the pressure control unit controls the pressure of the liquid in the supply path to a positive pressure and the pressure of the liquid in the recovery path to a negative pressure. (Configuration 17) 17. The recording apparatus according to claim 16, wherein the pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the difference between the pressures is 2000 [Pa] or more. (Configuration 18) 18. The recording apparatus according to claim 16, wherein the pressure control unit controls the pressure of the liquid in the supply path and the recovery path so that the negative pressure of the liquid at the ejection port is −5000 [Pa] or more. (Configuration 19) the pressure control unit includes a first pressure adjustment mechanism that adjusts the pressure of the liquid to a negative pressure and sends the liquid to the supply path, and a second pressure adjustment mechanism that adjusts the pressure of the liquid to a negative pressure and sends the liquid to the recovery path, 19. The recording apparatus according to any one of configurations 16 to 18, wherein the first pressure adjustment mechanism is located above the ejection orifices. [Explanation of symbols]

[0120] 3...liquid ejection head, 10...printing element substrate, 13...ejection port, 15...printing element (energy generating element), 18...supply path, 19...recovery path, 230...pressure control unit

Claims

1. A recording element substrate having a discharge port, an energy generating element that generates energy to discharge liquid from the discharge port, a supply path that supplies liquid to the discharge port, and a recovery path that recovers liquid that was not discharged from the discharge port, A pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path, respectively, so that the pressure of the liquid at the discharge port becomes negative pressure. Equipped with, The pressure control unit includes a first pressure adjustment mechanism that adjusts the liquid pressure to negative pressure and sends it to the supply path, and a second pressure adjustment mechanism that adjusts the liquid pressure to negative pressure and sends it to the recovery path, and controls the liquid pressure in the supply path to positive pressure and the liquid pressure in the recovery path to negative pressure so that the difference between the liquid pressure in the supply path and the liquid pressure in the recovery path is 2000 [Pa] or more. The liquid discharge head is characterized in that the first pressure adjustment mechanism is located above the discharge port.

2. The liquid dispensing head according to claim 1, characterized in that the flow resistance value of the supply path and the recovery path is 100 [Pa・min / ml / cP] or less.

3. The liquid discharge head according to claim 1, characterized in that the pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path so that the negative pressure of the liquid at the discharge port is -5000 [Pa] or more.

4. The first pressure adjustment mechanism includes an orifice and a movable valve configured to open and close the orifice. The liquid discharge head according to claim 1, characterized in that, in the direction of gravity, the height difference between the center of the orifice and the surface on which the discharge port is formed is 30 mm or more.

5. The liquid discharge head according to claim 1, characterized in that the first pressure adjustment mechanism and the second pressure adjustment mechanism are arranged offset from each other in the direction of gravity.

6. The first pressure adjustment mechanism includes a first orifice, a first pressure receiving plate configured to be movable by the pressure difference between the inside and outside of the first pressure adjustment mechanism, and a first movable valve configured to open and close the first orifice in conjunction with the movement of the first pressure receiving plate. The liquid discharge head according to claim 1, characterized in that the second pressure adjustment mechanism comprises a second orifice, a second pressure receiving plate configured to be movable by the pressure difference between the inside and outside of the second pressure adjustment mechanism, and a second movable valve configured to open and close the second orifice in conjunction with the movement of the second pressure receiving plate.

7. The first movable valve is configured to move from a position that closes the first orifice to a position that opens the first orifice when pressed against the first pressure plate. The first pressure adjustment mechanism has a first biasing member that biases the first pressure receiving plate in a direction away from the first movable valve, The second movable valve is configured to move from a position that closes the second orifice to a position that opens the second orifice when pressed against the second pressure plate. The second pressure adjustment mechanism has a second biasing member that biases the second pressure receiving plate in a direction away from the second movable valve, The liquid discharge head according to claim 6, characterized in that the biasing force of the first biasing member is smaller than the biasing force of the second biasing member.

8. The first pressure adjustment mechanism includes a first biasing member that biases the first movable valve in a direction that moves the first movable valve from a position in which the first orifice is open to a position in which the first orifice is closed. The second pressure adjustment mechanism includes a second biasing member that biases the second movable valve in a direction that moves the second movable valve from a position in which it opens the second orifice to a position in which it closes the second orifice. The liquid discharge head according to claim 6, characterized in that the biasing force of the first biasing member is smaller than the biasing force of the second biasing member.

9. The liquid discharge head according to claim 6, characterized in that the pressure-receiving area of ​​the first pressure-receiving plate is larger than the pressure-receiving area of ​​the second pressure-receiving plate.

10. The liquid discharge head according to claim 6, characterized in that the area of ​​the pressure-receiving portion of the first movable valve that receives pressure from the first orifice side is different from the area of ​​the pressure-receiving portion of the second movable valve that receives pressure from the second orifice side.

11. The liquid discharge head according to claim 1, characterized in that the liquid whose pressure is controlled by the pressure control unit contains titanium dioxide or hollow particles.

12. The liquid dispensing head according to claim 1, characterized in that the viscosity of the liquid whose pressure is controlled by the pressure control unit is 3 [cp] or more.

13. The liquid discharge head according to claim 1, characterized in that the water content of the liquid whose pressure is controlled by the pressure control unit is 50% or more.

14. A liquid discharge head comprising a recording element substrate having a discharge port, an energy generating element that generates energy to discharge liquid from the discharge port, a supply path that supplies liquid to the discharge port, and a recovery path that recovers liquid that was not discharged from the discharge port, A pressure control unit controls the pressure of the liquid in the supply path and the pressure of the liquid in the recovery path, respectively, so that the pressure of the liquid at the discharge port becomes negative pressure. Equipped with, The pressure control unit includes a first pressure adjustment mechanism that adjusts the liquid pressure to negative pressure and sends it to the supply path, and a second pressure adjustment mechanism that adjusts the liquid pressure to negative pressure and sends it to the recovery path, and controls the liquid pressure in the supply path to positive pressure and the liquid pressure in the recovery path to negative pressure so that the difference between the liquid pressure in the supply path and the liquid pressure in the recovery path is 2000 [Pa] or more. The recording device is characterized in that the first pressure adjustment mechanism is located above the discharge port.

15. The recording device according to claim 14, characterized in that the pressure control unit controls the pressure of the liquid in the supply path and the recovery path so that the negative pressure of the liquid at the discharge port is -5000 [Pa] or more.

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