Liquid discharge head and liquid discharge device

Abstract

To reduce temperature rise of an ink flowing into a liquid discharge head body.SOLUTION: A liquid discharge head includes: a plurality of recording element substrates for discharging a liquid; a passage member for supplying the liquid to the recording element substrates; and a liquid supply unit which supplies the liquid to a passage of the passage member and is disposed at the opposite side of the recording element substrates with respect to the passage member. The liquid supply unit directly or indirectly contacts with a part of the passage member.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus, and more particularly to a configuration for managing the temperature of a liquid ejection head. [Background technology]

[0002] Some liquid ejection heads, such as recording heads that eject ink, are provided with a filter on the upstream side of the head body to prevent clogging of the ejection section, and a negative pressure generating mechanism to control the liquid pressure in the ejection section within a predetermined range.

[0003] In a so-called full-line head in which the ejection ports are arranged across the width of the recording medium being conveyed, the filter area tends to be large because the ejection flow rate is large. In addition, a nozzle circulation configuration that circulates the ink to the ejection section may be adopted, and in this case, the negative pressure generating mechanism is often installed on both the upstream and downstream sides of the ejection section. As a result, there is a problem that the head becomes large. In response to this, as described in Patent Document 1, a configuration is known in which the filter, negative pressure generating mechanism, and distribution flow paths connecting these to the head body are arranged close to the top of the head body, thereby achieving miniaturization. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-10757 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration shown in Patent Document 1, the ink passes through a distribution channel and a filter channel that are in contact with almost the entire ejection head before flowing into the head body, so heat generated by the ejection operation of the ejection head is transferred to the ink, causing it to rise in temperature. As a result, the temperature of the ink flowing into the head body also increases, and the ink temperature at the ejection section also increases. This can cause problems such as thickening due to evaporation of the ink and changes in colorant concentration.

[0006] An object of the present disclosure is to provide a liquid ejection head capable of reducing the rise in temperature of ink flowing into the liquid ejection head body, and a liquid ejection apparatus including the same. [Means for solving the problem]

[0007] A liquid ejection head according to one aspect of the present disclosure comprises a plurality of recording element substrates for ejecting liquid, a flow path member for supplying liquid to the recording element substrates, and a liquid supply unit for supplying liquid to a flow path of the flow path member, the liquid supply unit being arranged on the opposite side of the flow path member to the recording element substrates, and is characterized in that the liquid supply unit directly or indirectly abuts a portion of the flow path member. Effect of the Invention

[0008] According to the present invention, it is possible to reduce the temperature rise of the ink flowing into the liquid ejection head body. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an example of a liquid ejection device. [Diagram 2] FIG. 1 is a conceptual diagram of a control system. [Diagram 3] FIG. 2 is a schematic diagram of an ink supply system. [Figure 4] FIG. 2 is a perspective view of a liquid ejection head. [Diagram 5] FIG. 2 is an exploded view of the liquid ejection head. [Figure 6] FIG. [Figure 7]FIG. [Figure 8] 1A and 1B are perspective and cross-sectional views of a flow path. [Figure 9] 1A and 1B are perspective and exploded views of a dispensing module; [Figure 10] FIG. [Figure 11] FIG. 2 is a cross-sectional view of a recording element substrate. [Figure 12] FIG. 4 is a schematic diagram of a temperature control area of ​​a recording element substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the following description does not limit the scope of the present disclosure. As an example, the present embodiment employs a thermal method in which a heating element generates bubbles to eject liquid, but the present disclosure can also be applied to liquid ejection heads employing a piezo method or various other liquid ejection methods.

[0011] (First embodiment) First, the temperature rise of ink flowing into the head body, which the embodiment of the present invention aims to solve, will be described in detail. The recording element substrate constituting the head body is provided with a heating element, and the temperature rises due to the driving of the heating element accompanying the ejection operation. Therefore, the flow path members directly or indirectly joined to the recording element substrate, for example, the first flow path member 50 and the second flow path member 60 shown in FIG. 5, etc., receive heat from the recording element substrate constituting the ejection module 200 and rise in temperature. As a result, heat is transferred from the liquid flow path member 50 etc. to the liquid supply section arranged on the upper part of the second flow path member 60 (opposite side of the ejection module 200) in the figure, and the ink rises in temperature in the liquid supply section. In addition, since the heat is carried to one side (downstream side) in the direction in which the liquid flow path members 50 and 60 extend due to the flow of ink in the flow path inside the liquid flow path member 50, when the liquid supply section abuts against the downstream flow path member, the temperature rise in the supply section becomes even more remarkable. As a result, the temperature of the ink flowing into the head body rises, causing problems such as thickening due to evaporation of the ink.

[0012] In the following, an embodiment of the present invention for solving the above problems will be described in detail.

[0013] <Overall configuration of liquid ejection device> FIG. 1 shows a liquid ejection device 1000 according to the present embodiment. In the figure, the X direction is the transport direction of the recording medium 2, the Y direction is the width direction of the recording medium 2, and the Z direction is the vertical direction. The liquid ejection device 1000 of the present embodiment includes a paper transport unit 1 that transports the recording medium 2, and a line-type liquid ejection head 3 arranged approximately perpendicular to the X direction, which is the transport direction of the recording medium 2. The liquid ejection head 3 is capable of recording a color image on the recording medium 2 by ejecting ink of cyan (C), magenta (M), yellow (Y), and black (Bk). The four liquid ejection heads 3 are arranged in the X direction in the order of cyan, magenta, yellow, and black, and the inks are applied to the recording medium 2 in this order. In each liquid ejection head 3, a plurality of ejection openings that eject ink are arranged in the Y direction.

[0014] 1 shows cut paper as the recording medium 2, the recording medium 2 may be continuous paper supplied from a roll of paper. The recording medium is not limited to paper and may be film or the like.

[0015] 2 is a block diagram for explaining the control configuration of the liquid ejection device 1000. The control unit 500 is composed of a CPU and the like, and controls the entire liquid ejection device 1000 while using a RAM 502 as a work area in accordance with programs and various parameters stored in a ROM 501. The control unit 500 performs predetermined image processing on image data received from an externally connected host device 600 in accordance with the programs and parameters stored in the ROM 501, and generates ejection data that can be ejected by the liquid ejection head 3. Then, the liquid ejection head 3 is driven in accordance with this ejection data, causing it to eject ink at a predetermined frequency.

[0016] During the ejection operation by the liquid ejection head 3, the control unit 500 drives the transport motor 503 to transport the recording medium 2 in the X direction at a speed corresponding to the drive frequency. As a result, an image is recorded on the recording medium 2 according to the image data received from the host device 600. Information on the use area of ​​the ejection ports used for ejection in the liquid ejection head 3 is stored in the ROM 501 in a rewritable manner for each liquid ejection head 3. The method of setting the use area will be described in detail later.

[0017] <Ink circulation system> FIG. 3 is a schematic diagram showing a circulation path applied to the liquid ejection device of this embodiment, in which the liquid ejection head 3 is fluidly connected to a first circulation pump 1002, a buffer tank 1003, and the like. In FIG. 3, only a path through which one color of ink of CMYK ink flows is shown for the sake of simplicity of explanation, but in reality, circulation paths corresponding to a plurality of colors are provided in the liquid ejection head 3 and the liquid ejection device body. The buffer tank 1003 as a sub-tank connected to the main tank 1006 has an air communication port (not shown) that communicates the inside of the tank with the outside, and is capable of discharging air bubbles in the ink to the outside. The buffer tank 1003 is also connected to a refill pump 1005. When liquid is consumed in the liquid ejection head 3 by discharging (discharging) ink from the ejection port of the liquid ejection head for recording by ejecting ink, suction recovery, and the like, the refill pump 1005 transfers the amount of consumed ink from the main tank 1006 to the buffer tank 1003.

[0018] The first circulation pump 1002 has a role of drawing liquid from the liquid connection portion 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 certain amount of ink to flow inside the common recovery channel 212.

[0019] The negative pressure control unit 230 is provided between the second circulation pump 1004 and the liquid ejection unit 300. Therefore, 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 even if the flow rate of the circulation system varies due to a difference in the duty for performing printing.

[0020] As shown in FIG. 3, the negative pressure control unit 230 includes two pressure adjustment mechanisms, each of which is set with a different control pressure. Of the two negative pressure adjustment mechanisms, the relatively high pressure setting side (indicated as H in FIG. 3) and the relatively low pressure side (indicated as L in FIG. 3) are connected to the common supply flow path 211 and the common recovery flow path 212 in the liquid ejection unit 300, respectively, via the liquid supply unit 220. The liquid ejection unit 300 is provided with the common supply flow path 211, the common recovery flow path 212, and individual supply flow paths 213a and individual recovery flow paths 213b that communicate with each recording element substrate. Since the individual flow path 213 communicates with the common supply flow path 211 and the common recovery flow path 212, a part of the liquid flown by the second circulation pump 1004 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 (arrow in FIG. 3). This is because a pressure difference is provided between the pressure adjustment mechanism H connected to the common supply flow path 211 and the pressure adjustment mechanism L connected to the common recovery flow path 212, and the first circulation pump 1002 is connected only to the common recovery flow path 212.

[0021] Therefore, the liquid is supplied from the supply system of the liquid ejection device 1000 to the liquid ejection head 3, and the liquid that has passed through the liquid ejection head 3 is recovered to the supply system of the liquid ejection device 1000. As a result, the liquid can be circulated through the path of the liquid ejection device 1000 and the path of the liquid ejection head 3. In the liquid ejection unit 300 of this embodiment, a flow of liquid that passes through the common recovery flow path 212 and a flow from the common supply flow path 211 through each recording element substrate 10 to the common recovery flow path 212 are generated. Therefore, heat generated in each recording element substrate 10 can be discharged to the outside of the recording element substrate 10 by the flow from the common supply flow path 211 to the common recovery flow path 212. With this configuration, when recording is being performed by the liquid ejection head 3, a flow of ink can be generated even in ejection ports and pressure chambers that are not performing recording, so that thickening of the ink in those areas can be suppressed. Viscous ink and foreign matter in the ink can be discharged to the common recovery flow path 212. Therefore, the liquid ejection head 3 of this embodiment is capable of high-speed, high-quality recording.

[0022] <Configuration of Liquid Ejection Head> 4(a) and 4(b) are perspective views of the liquid ejection head 3 according to this embodiment. FIG. 5 is an exploded perspective view of FIG. 4. The liquid ejection head 3 is a line-type liquid ejection head in which 17 recording element substrates 10 capable of ejecting ink are arranged in a straight line (arranged in-line). As shown in FIG. 4(a) and FIG. 4(b), the liquid ejection head 3 includes each recording element substrate 10, a signal input terminal 91 and a power supply terminal 92 electrically connected via a flexible wiring substrate 40 and an electric wiring substrate 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to a control unit of the liquid ejection device 1000, and supply an ejection drive signal and power required for ejection to the recording element substrate 10, respectively. By consolidating the wiring by the electric circuit in the electric wiring substrate 90, the number of signal output terminals 91 and the power supply terminals 92 can be made smaller than the number of recording element substrates 10. This allows for a smaller number of electrical connections to be removed when assembling the liquid ejection head 3 to the liquid ejection device 1000 or when replacing the liquid ejection head.

[0023] The housing 80 is composed of a liquid discharge unit support part 81 and an electric wiring board support part 82, and supports the liquid discharge unit 300 and the electric wiring board 90 while ensuring the rigidity of the liquid discharge head 3. The electric wiring board support part 82 is for supporting the electric wiring board 90, and is fixed to the liquid discharge unit support part 81 by screwing. The liquid discharge unit support part 81 is provided with openings 83 and 84 into which the joint rubber 100 is inserted. The liquid supplied from the liquid supply unit 220 is led to the second flow path member 60 constituting the liquid discharge unit 300 through the joint rubber 100. In this embodiment, the flow directions of the common supply flow path 211 and the common recovery flow path 212 (see FIG. 7) are the same, but the present invention is also applicable even if they are reversed. As described above, the liquid discharge unit (head body) 300 is composed of the flow path member 210 including the first flow path member 50 and the second flow path member 60, and a plurality of discharge modules 200 including the recording element substrate 10.

[0024] Next, the configuration of the flow path member 210 included in the liquid discharge unit 300 will be described. As shown in Fig. 5, the flow path member 210 is formed by laminating a first flow path member 50 and a second flow path member 60, and a plurality of discharge modules 200 are bonded to the bonding surface of the first flow path member 50 with an adhesive (not shown). As a result, the liquid supplied from the liquid supply unit 220 is distributed to each discharge module 200. In addition, the liquid circulating from the discharge modules 200 flows into a common recovery flow path 212 in the flow path member, and is discharged to the outside of the head via a liquid connection part 111 of the liquid discharge head 3. In addition, the flow path member 210 is fixed to the liquid discharge unit support part 81 by screwing.

[0025] In the above-described configuration of the liquid ejection head 3, the liquid supply unit 220 has a length that is approximately half the length of the flow path member 210 constituting the liquid ejection unit 300, as shown by the distance between two auxiliary lines shown by dashed lines in FIG. 5. This allows the area where the liquid supply unit 220 and the flow path member 210 are in direct contact with each other or indirectly through another member to be limited to a part of the length of the liquid ejection unit 300, and the amount of heat transferred from the liquid ejection unit 300 through the flow path member 210 can be suppressed. As a result, it is possible to suppress the temperature rise of the ink supplied from the liquid supply unit 220, and it is possible to prevent the ink from thickening due to the temperature rise in the ink ejection section of the liquid ejection unit 300. The length of the liquid supply unit 220 is not limited to the above-described 1 / 2. From the viewpoint of suppressing the amount of heat transferred to the liquid supply unit 220, the shorter the length of the liquid supply unit 220, the better it is to be 1 / 2 or less. However, in order to ensure a certain degree of area for the filter 221 (FIG. 6), it is preferable that the length of the liquid supply unit 220 is 1 / 4 or more of the length of the liquid ejection unit 300. By ensuring a certain degree of area for the filter 221, it is possible to suppress stagnation of the flow of liquid. In addition, since the ink flow in the common flow path in the first flow path member 50 constituting the flow path member 210 is from the left (upstream side) to the right (downstream side) in Fig. 5, the ink in the common flow path receives a greater amount of heat from the liquid ejection unit 300 on the downstream side. For this reason, arranging the liquid supply unit 220 on the upstream side (between the above two auxiliary lines) is effective in reducing the amount of heat transferred to the liquid supply unit 220.

[0026] Fig. 6(a) is an exploded perspective view of the liquid supply unit 220, and Fig. 6(b) is an explanatory diagram showing the flow of liquid within the liquid supply unit 220. The liquid supply unit 220 includes an upper lid part 220a that abuts against the negative pressure control unit 230, a liquid supply unit main body part 220b, a filter 221, and a lower lid part 220c. The liquid supply unit 220 is arranged in this order: upper lid part 220a, liquid supply unit main body part 220b, filter 221, and lower lid part 220c.

[0027] The upper cover 220a has a plurality of openings. In this embodiment, the upper cover 220a has five openings. This allows the upper cover 220a to flow liquid from the first circulation pump 1002 to the negative pressure control unit 230. The liquid supply unit main body 220b includes a liquid connection portion 111, two openings for sending liquid to the negative pressure control unit 230, and two flow paths for sending liquid discharged from the negative pressure control unit 230 to the liquid discharge unit 300. The lower cover 220c includes a flow path for sending liquid through the filter 221 and the negative pressure control unit 230 to the flow path member 210.

[0028] Next, the flow of liquid in the liquid supply unit 220 will be described. As shown in FIG. 6(b), the liquid flows in from the liquid connection part 111 in the liquid supply unit 220 (arrow a) and flows on the back side of the liquid supply unit main body part 220b (arrow b). Then, the liquid passes through a filter 221 to remove foreign matter in the liquid being supplied, and flows into the negative pressure control unit 230 arranged on the front side of the liquid supply unit main body part 220b (arrows c1, c2). The negative pressure control unit 230 is a unit consisting of a pressure adjustment valve. The negative pressure control unit 230 largely attenuates the pressure loss change in the supply system of the liquid ejection device 1000 (the supply system on the upstream side of the liquid ejection head 3) that occurs with the fluctuation of the flow rate of the liquid by the action of the valves and spring members provided therein. Then, the negative pressure control unit 230 can stabilize the negative pressure change downstream of the pressure control unit (the liquid ejection unit 300 side) within a certain range. The ink flowing out from the negative pressure control unit 230 (arrows d1, d2) flows in the longitudinal direction of the liquid supply unit 220 (arrows e1, e2), and flows into the liquid ejection unit 300.

[0029] As shown in Fig. 6(b), it is preferable to place the filter 221 upstream of the negative pressure control unit 230. This makes it possible to keep the pressure inside the head constant even if the pressure loss increases over time due to clogging of the filter 221 or the like. The negative pressure control unit 230 also has two built-in pressure adjustment valves, each set to a different control pressure. By connecting the high pressure side to the common supply flow path 211 in the liquid ejection unit 300 via the liquid supply unit 220 and the low pressure side to the common recovery flow path 212, it is possible to circulate ink in the pressure chambers described above.

[0030] As described above, the ink flowing into the head main body passes through the liquid supply unit that directly or indirectly abuts on the liquid ejection unit 300, which has been heated by the heat generated by the recording element substrate, and so the ink temperature rises within the liquid supply unit. In contrast, by configuring the supply unit 220 to directly or indirectly abut only a portion of the first flow path member and the second flow path member, it is possible to reduce the temperature rise of the ink within the supply unit described above.

[0031] Figures 7(a) to (d) are diagrams for explaining the detailed configuration of the flow path member 210. Figure 7(a) shows the contact surface of the support member 30 with the recording element substrate 10, Figure 7(b) shows the contact surface of the first flow path member 50 with the support member 30, Figure 7(c) shows a middle layer cross section of the first flow path member, and Figure 7(d) shows the surface of the second flow path member on the liquid discharge unit support section 81 side. Figures 7(a) to (c) are diagrams viewed from the discharge port surface, and Figure 7(d) is a diagram viewed from the opposite side, the liquid discharge unit support section 81 side.

[0032] A plurality of support members 30 arranged in the Y direction are disposed on the first flow path member 50, and one recording element substrate 10 is disposed on each support member 30. With this configuration, by adjusting the number of arranged ejection modules 200, liquid ejection heads 3 of various sizes can be assembled.

[0033] 7(a), a support member communication port 31 that is fluidly connected to the recording element substrate 10 and serves as the individual supply flow path 213a and the individual recovery flow path 213b described in Fig. 3 is formed on the surface of the support member 30 that abuts against the recording element substrate 10. As shown in Fig. 6(b), the support member communication port 31 is fluidly connected to the common supply flow path 211 or the common recovery flow path 212 via the communication port 51 formed in the flow path member 50 in Fig. 1.

[0034] 7(c), common flow path grooves 61, 62 extending in the Y direction are formed in the middle layer of the first flow path member 50, and serve as the common supply flow path 211 and the common recovery flow path 212 described in FIGS. 3(a) and 3(b). As shown in FIG. 7(d), a common communication port 63 that is fluidly connected to the liquid supply unit 220 is formed at both ends or one end of the common flow path grooves 61, 62.

[0035] 8(a) and (b) are a perspective view and a cross-sectional view for explaining a flow path structure formed inside the flow path member 210, the support member 30, and the cover plate 20. Fig. 8(a) is an enlarged perspective view of the flow path member 210, the support member 30, and the cover plate 20 as viewed from the Z direction, and Fig. 8(b) is an FF cross-sectional view of Fig. 8(a).

[0036] The recording element substrate 10 of the discharge module 200 is placed on the communication port 51 of the first flow path member 50 via the support member 30. Note that although the communication port 51 corresponding to the common recovery flow path 212 is not shown in Fig. 8(b), it is clear from Fig. 8(a) that it is shown in another cross section.

[0037] As already described, the common supply flow path 211 is connected to the first negative pressure control unit 230 with a relatively high pressure, and the common recovery flow path 212 is connected to the second negative pressure control unit 230 with a relatively low pressure. An ink supply path is formed that supplies ink to a flow path formed in the recording element substrate 10 through the common communication port 63 (see FIG. 7), the common supply flow path 211, and the support member communication port 31. Similarly, an ink recovery path is formed from the flow path in the recording element substrate 10 through the support member communication port 31, the communication port 51, the common recovery flow path 212, and the common communication port 63 (see FIG. 8). While the ink is circulated in this manner, the recording element substrate 10 performs an ejection operation according to the ejection data, and the ink that is supplied through the ink supply path and is not consumed by the ejection operation is recovered through the ink recovery path.

[0038] <Explanation of the discharge module> FIG. 9(a) is a perspective view showing one discharge module 200, and FIG. 9(b) is an exploded view thereof. In the manufacturing method of the discharge module 200, first, the recording element substrate 10 and the flexible wiring substrate 40 are bonded onto the support member 30 in which the liquid support member communication port 31 is provided in advance. Then, the terminal 16 on the recording element substrate 10 and the terminal 41 on the flexible wiring substrate 40 are electrically connected by wire bonding, and then the wire bonding portion (electrical connection portion) is covered and sealed with a sealant 110. The terminal 42 on the flexible wiring substrate 40 opposite the recording element substrate 10 is electrically connected to the connection terminal 93 (see FIG. 5) of the electrical wiring substrate 90. The support member 30 is a support body that supports the recording element substrate 10 and is also a flow path member that fluidly communicates the recording element substrate 10 and the flow path member 210, so it is preferable that the support member 30 has a high flatness and can be joined to the recording element substrate with sufficiently high reliability. For example, alumina or a resin material is preferable as the material.

[0039] <Explanation of the structure of the recording element substrate> FIG. 10(a) shows a plan view of the surface of the recording element substrate 10 on which the ejection ports 13 are formed, FIG. 10(b) shows an enlarged view of the portion indicated by A in FIG. 10(a), and FIG. 10(c) shows a plan view of the back surface of FIG. 10(a). Here, the configuration of the recording element substrate 10 in this embodiment will be described. Hereinafter, the direction in which the ejection port array in which the multiple ejection ports 13 are arranged extends will be referred to as the "ejection port array direction". As shown in FIG. 10(b), a recording element 15, which is a heat generating element (pressure generating element) for foaming the liquid by utilizing the thermal energy generated by the ejection port 13, is disposed at a position corresponding to each ejection port 13. A pressure chamber 23 having the recording element 15 therein is partitioned by a partition wall 22. The recording element 15 is electrically connected to a terminal 16 by an electric wiring (not shown) provided on the recording element substrate 10. The recording elements 15 generate heat based on pulse signals input from the control circuit of the liquid ejection device 1000 via the electric wiring board 90 (see FIG. 5) and the flexible wiring board 40 (see FIG. 9) to boil the liquid. The liquid is ejected from the ejection ports 13 by the bubbling force caused by this boiling. As shown in FIG. 10(b), along each ejection port row, a liquid supply path 18 extends on one side, and a liquid recovery path 19 extends on the other side. The liquid supply path 18 and the liquid recovery path 19 are flow paths that extend in the ejection port row direction and are provided in the recording element substrate 10, and communicate with the ejection ports 13 via the supply port 17a and the recovery port 17b, respectively.

[0040] As shown in FIG. 10(c), a sheet-like cover plate 20 is laminated on the back surface of the recording element substrate 10, opposite to the surface on which the ejection ports 13 are formed, and the cover plate 20 is provided with a plurality of openings 21 communicating with the liquid supply passages 18 and the liquid recovery passages 19, which will be described later. In this embodiment, the cover plate 20 is provided with four supply openings 21a for each liquid supply passage 18 and three recovery openings 21b for each liquid recovery passage 19, but the number of openings is not limited to this. As shown in FIG. 10(b), each opening 21 of the cover plate 20 communicates with the communication port 51 shown in FIG. 8(a). The cover plate 20 is preferably one having sufficient corrosion resistance against liquid, and high accuracy is required for the opening shape and opening position of the opening 21 so that ink can be supplied to the pressure chamber.

[0041] FIG. 11 is a perspective view showing a cross section of the recording element substrate 10 and the cover plate 20 at II in FIG. 10(a). In FIG. 11, four rows of ejection ports are shown in the ejection port forming member 12 of the recording element substrate 10, but the present invention may have more or less rows of ejection ports. Here, the flow of liquid in the recording element substrate 10 will be described. The cover plate 20 functions as a lid that forms part of the walls of the liquid supply path 18 and the liquid recovery path 19 formed in the substrate 11 of the recording element substrate 10. The recording element substrate 10 is formed by laminating the substrate 11 made of Si or the like and the ejection port forming member 12 made of a photosensitive resin, and the cover plate 20 is bonded to the back surface of the substrate 11. The recording elements 15 are formed on one surface of the substrate 11 (see FIG. 10), and grooves that form the liquid supply path 18 and the liquid recovery path 19 extending along the ejection port rows are formed on the back surface of the substrate 11. The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the cover plate 20 are connected to a common supply flow path 211 and a common recovery flow path 212 in the flow path member 210, respectively, and a pressure difference is generated between the liquid supply path 18 and the liquid recovery path 19. This pressure difference causes the liquid in the liquid supply path 18 provided in the substrate 11 to flow to the liquid recovery path 19 via the supply port 17a, the pressure chamber 23, and the recovery port 17b (arrow C in FIG. 11). This flow allows the thickened ink, bubbles, foreign matter, and the like that are generated by evaporation from the ejection port 13 in the ejection port 13 and the pressure chamber 23 that are not ejecting to be collected into the liquid recovery path 19. In addition, it is possible to suppress the ink in the ejection port 13 and the pressure chamber 23 from becoming thicker and the concentration of the coloring material from increasing. The liquid recovered to the liquid recovery path 19 is recovered in the order of the opening 21 and the support member communication port 31 of the support member 30, the communication port 51 of the first flow path member 50, and the common recovery flow path 212, as shown in Figure 8, and is then recovered to the supply path of the liquid ejection device 1000.

[0042] FIG. 12 shows a schematic diagram of each recording element substrate 10 divided into a plurality of areas for temperature adjustment. A temperature sensor 301 and an individually controllable sub-heater 302 are provided for each area, and the control unit 500 (see FIG. 2) adjusts the temperature based on the temperature set for each area using the temperature sensor 301 and the sub-heater 302. That is, the control unit 500 drives the sub-heater 302 only for areas where the temperature detected by the temperature sensor 301 is equal to or lower than the target temperature. By setting the target temperature of the recording element substrate 10 to a relatively high temperature, it is possible to reduce the viscosity of the ink and perform the ejection operation and circulation favorably. In addition, by performing such temperature control and suppressing the temperature variation within the recording element substrate 10 and the temperature variation between the plurality of recording element substrates 10 within a predetermined range, it is possible to reduce the ejection amount variation caused by the temperature variation and suppress density unevenness in the recorded image.

[0043] In terms of image quality, it is preferable that the target temperature of the recording element substrate 10 is set to a temperature equal to or higher than the equilibrium temperature of the recording element substrate 10 when all the recording elements 15 are driven at the highest possible driving frequency. As the temperature sensor 301, a diode sensor, an aluminum sensor, or the like can be used.

[0044] Incidentally, the recording elements 15, which are heat generating elements, can also be used as heating means for the recording element substrate 10. Specifically, the recording element substrate 10 can be heated by applying a voltage to the recording elements 15 that does not cause bubbles to form. In this embodiment, the recording elements 15 may be used as heating means instead of the sub-heater 302, or the sub-heater 302 and the recording elements 15 may be used in combination.

[0045] <Other Examples> This embodiment illustrates a head that prints one color with one head, but the present invention can also be applied to a multi-color head that prints multiple colors with one head.

[0046] In addition, although the present embodiment is described on the premise of a so-called thermal head that heats and ejects ink, it can also be applied to a liquid ejection head that uses a piezoelectric element. This is because a drive waveform generating circuit (IC) arranged to apply a drive waveform to the piezoelectric element also generates heat in a head that uses a piezoelectric element, and therefore, when the IC is arranged near the recording element substrate, the same phenomenon as that of the thermal head described above occurs.

[0047] Furthermore, in this embodiment, a configuration (hereinafter, nozzle circulation configuration) is shown in which ink circulates through the pressure chambers 23 in the recording element substrate, where the rise in temperature downstream of the common flow path is particularly noticeable, but the present invention is not limited to the nozzle circulation configuration.

[0048] The disclosure of this embodiment includes configurations typified by the following liquid ejection head examples.

[0049] <Configuration 1> A plurality of recording element substrates for ejecting liquid; a flow path member for supplying liquid to the recording element substrate; a liquid supply unit that supplies liquid to a flow path of the flow path member, the liquid supply unit being disposed on an opposite side of the flow path member from the recording element substrate; The liquid ejection head, wherein the liquid supply unit directly or indirectly contacts a part of the flow path member.

[0050] <Configuration 2> 2. The liquid ejection head according to configuration 1, wherein the length of the liquid supply unit in the longitudinal direction is equal to or less than half the length of the flow path member in the longitudinal direction.

[0051] <Configuration 3> 3. The liquid ejection head according to configuration 2, wherein the length of the liquid supply unit in the longitudinal direction is equal to or greater than ¼ of the length of the flow path member in the longitudinal direction.

[0052] <Configuration 4> 4. The liquid ejection head according to any one of configurations 1 to 3, wherein a center in a longitudinal direction of the liquid supply unit is disposed upstream of a center of the flow path member in the flow path of the flow path member.

[0053] <Component 5> 5. The liquid ejection head according to any one of configurations 1 to 4, wherein the flow path member has a common recovery flow path that directly or indirectly recovers the liquid recovered from the recording element substrate.

[0054] <Component 6> 6. The liquid ejection head according to any one of configurations 1 to 5, wherein the liquid flows in the flow path member in the same direction.

[0055] <Component 7> A liquid ejection head described in any one of configurations 1 to 6, characterized in that the liquid flow direction in the flow path member is reversed, and the longitudinal center of the liquid supply unit is positioned upstream of the common recovery flow path from the center of the flow path member.

[0056] <Component 8> The liquid ejection head according to any one of configurations 1 to 7, further comprising a negative pressure generating mechanism disposed on the side of the flow path member opposite to the recording element substrate.

[0057] <Component 9> 9. The liquid ejection head according to configuration 8, wherein a filter is disposed on the opposite side of the flow path member to the recording element substrate and upstream of the negative pressure generating mechanism.

[0058] <Component 10> 10. The liquid ejection head according to configuration 9, wherein the length in the longitudinal direction of the negative pressure generating mechanism is equal to or greater than half the length of the liquid supply unit.

[0059] <Component 11> 11. The liquid ejection head according to any one of configurations 1 to 10, wherein the recording element substrate includes a pressure generating mechanism.

[0060] <Component 12> 12. The liquid ejection head according to configuration 11, wherein the pressure generating mechanism is a heating element.

[0061] <Component 13> 13. The liquid ejection head according to configuration 12, wherein the pressure generating mechanism is a piezoelectric element, and a drive circuit board for driving the piezoelectric element is disposed on the recording element board side of the flow path member.

[0062] <Component 14> A liquid tank for containing the liquid; 14. A liquid ejection device comprising: a liquid ejection head according to any one of configurations 1 to 13, connected to the liquid tank. [Explanation of symbols]

[0063] 10 Recording element board 210 Flow path components 220 Liquid Supply Unit

Claims

1. Multiple recording element substrates for dispensing liquid, A flow channel member having a common flow channel that communicates with the plurality of recording element substrates and liquid, A negative pressure generating mechanism is positioned on the opposite side of the recording element substrate from the flow channel member, A liquid supply unit for supplying liquid to the flow path of the flow path member, comprising a liquid supply unit disposed between the flow path member and the negative pressure generating mechanism, a liquid discharge head, The longitudinal length of the liquid supply unit is shorter than the longitudinal length of the flow path member. The common channel extends in the longitudinal direction and is configured such that liquid flows from the first side in the longitudinal direction to the second side opposite the first side. The liquid supply unit is arranged such that, in the longitudinal direction, the center of the liquid supply unit is located on the first side of the common flow path with respect to the center of the flow path member. The liquid discharge head is characterized by comprising only one set of a negative pressure control unit and a liquid supply unit that communicates with the negative pressure control unit and the flow path member.

2. The liquid discharge head according to claim 1, characterized in that the longitudinal length of the liquid supply unit is 1 / 2 or less of the longitudinal length of the flow channel member.

3. The liquid discharge head according to claim 2, characterized in that the longitudinal length of the liquid supply unit is 1 / 4 or more of the longitudinal length of the flow path member.

4. The liquid discharge head according to claim 1, characterized in that the common channel includes a common supply channel for directly or indirectly supplying liquid to the plurality of recording element substrates, and a common recovery channel for directly or indirectly recovering the liquid recovered from the plurality of recording element substrates.

5. The liquid discharge head according to claim 4, characterized in that the liquid flow direction in the common supply channel and the common recovery channel are the same.

6. The liquid discharge head according to claim 1, characterized in that the direction of liquid flow in the flow channel member is reversed, and the longitudinal center of the liquid supply unit is located upstream of the common recovery channel from the center of the flow channel member.

7. The liquid discharge head according to claim 1, characterized in that the negative pressure generating mechanism is arranged on the side of the flow channel member opposite to the recording element substrate.

8. The liquid discharge head according to claim 7, characterized in that the filter is positioned on the side of the flow channel member opposite to the recording element substrate and upstream of the negative pressure generation mechanism.

9. The liquid discharge head according to claim 8, characterized in that the longitudinal length of the negative pressure generating mechanism is approximately half or more of the longitudinal length of the liquid supply unit.

10. The liquid discharge head according to claim 1, characterized in that the recording element substrate is equipped with a pressure generation mechanism.

11. The liquid discharge head according to claim 10, characterized in that the pressure generating mechanism is a heating element.

12. The liquid discharge head according to claim 11, characterized in that the pressure generating mechanism is a piezoelectric element, and a drive circuit board for driving the piezoelectric element is arranged on the recording element board side of the flow path member.

13. A liquid tank for containing the aforementioned liquid, A liquid dispensing device comprising a liquid dispensing head according to any one of claims 1 to 12, which is connected to the liquid tank.

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