Recording device

Abstract

To provide a recording device capable of suppressing deformation of a flow passage member in a conveying direction of a recording medium.SOLUTION: A recording device 1000 comprises a liquid discharge head 3 that comprises a plurality of element substrates 10 and a flow passage member 210 which comprises a common supply passage 211 for supplying liquid to the plurality of element substrates 10 and a common collection passage 212 through which liquid is collected from the plurality of element substrates 10. The recording device 1000 further has, at upstream sides of the element substrates 10, heating means 250 for heating liquid flowing through the common supply passage 211.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a recording apparatus. [Background technology]

[0002] An example of a liquid ejection device (recording device) that ejects liquid onto a recording medium such as paper is an inkjet printer. An inkjet printer is equipped with a liquid ejection head, which is a part that ejects liquid. The liquid ejection head is equipped with an ejection port for ejecting liquid, a pressure generating element that generates pressure for ejecting liquid from the ejection port, a pressure chamber to which the pressure generated by the pressure generating element acts, and the like.

[0003] When performing an operation of discharging liquid from a discharge port, it is desirable that the viscosity of the liquid is within a desired range, and if the viscosity of the liquid is outside the desired range, there is a risk of the discharge performance being reduced. Patent Document 1 discloses a liquid discharge head in which a heating element for heating the liquid and controlling the viscosity of the liquid is provided near a pressure chamber. This adjusts the temperature of the liquid and controls the viscosity by driving the heating element to a degree that does not cause bubbles. Furthermore, the liquid discharge head described in Patent Document 1 has a recovery flow path for recovering the liquid from the pressure chamber in order to suppress an increase in the viscosity of the liquid caused by evaporation of the liquid from the discharge port, and has a flow path configuration that allows the liquid to circulate between the upstream and downstream of the pressure chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-213871 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, when a heating element for controlling the viscosity of the liquid is provided near the pressure chamber, the liquid heated by the heating element flows in the recovery flow path, which is a flow path downstream of the pressure chamber. Therefore, the temperature of the liquid flowing in the recovery flow path becomes higher than the temperature of the liquid flowing in the supply flow path, which is a flow path upstream of the pressure chamber and supplies the liquid to the pressure chamber. As a result, in a flow path member having a recovery flow path and a supply flow path, the temperature around the recovery flow path becomes higher than the temperature around the supply flow path, causing a temperature bias (temperature gradient) in the flow path member.

[0006] In addition, such a temperature gradient occurs in the same way when a heating element for controlling the viscosity of the liquid is provided in the pressure chamber as a pressure generating element for film boiling the liquid. Therefore, when the recovery flow path and the supply flow path are arranged side by side in the transport direction of the recording medium, the flow path member may deform in the transport direction of the recording medium due to the temperature gradient in the flow path member, which may affect the recording quality.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide a recording device that can suppress deformation of a flow path member in the transport direction of a recording medium. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a recording apparatus for recording on a recording medium, the recording apparatus having a liquid ejection head including a plurality of element substrates each including an ejection port for ejecting liquid and a heating element for heating the liquid, a common supply flow path communicating with the plurality of element substrates and supplying liquid to the plurality of element substrates, and a common recovery flow path communicating with the plurality of element substrates and recovering liquid from the plurality of element substrates, the recording apparatus comprising: the common supply flow path and the common recovery flow path are formed to be shifted from each other in a transport direction of the recording medium, A heating means for heating the liquid flowing in the common supply flow path is provided upstream of the element substrate. The temperature of the liquid flowing into the common supply flow passage is made higher than the temperature of the liquid flowing into the common recovery flow passage by the heating means. It is characterized by: Effect of the Invention

[0009] According to the present invention, it is possible to provide a recording device that can suppress deformation of a flow path member in the transport direction of a recording medium. [Brief description of the drawings]

[0010] [Figure 1] FIG. [Diagram 2] FIG. 4 is a schematic diagram showing a flow path of a liquid in the recording device. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a schematic view showing an internal structure of a flow path member in a comparative example. [Figure 7] FIG. 11 is a schematic view showing a cross section of a flow path member according to a third embodiment. [Figure 8] FIG. 8 is a perspective view of the flow path member shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The longer the flow path member, the greater the tendency for deformation of the flow path member to be. Therefore, the present invention is particularly suitable for use in so-called page-wide heads that have a flow path member longer than that of a so-called serial type liquid ejection head and that correspond to the recording width of a recording medium such as paper. A page-wide head is a head in which a plurality of ejection ports are arranged from one end to the other end of the recording medium in a direction intersecting the conveying direction of the recording medium. Below, an explanation will be given using a page-wide head as an example.

[0012] In addition, in the following embodiments, a configuration in which liquid circulates inside and outside the liquid ejection head will be described as an example, but the present invention is not limited to this. That is, the present invention can also be suitably used in a configuration in which liquid does not circulate inside and outside the liquid ejection head.

[0013] (Recording device) The recording device will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing an example of a recording device 1000 equipped with a liquid ejection head 3. The recording device 1000 shown in FIG. 1 ejects liquid from the liquid ejection head 3 onto an intermediate transfer body (intermediate transfer drum) 1007 to form an image pattern (print pattern) on the intermediate transfer body 1007, and then transfers the image pattern to a recording medium 2. In the recording device 1000, four single-color liquid ejection heads 3 corresponding to at least four types of ink, CMYK, are arranged in an arc shape along the intermediate transfer body 1007. As a result, full-color recording is performed on the intermediate transfer body 1007, and the recorded image pattern is appropriately dried on the intermediate transfer body 1007. Thereafter, the recorded image pattern is transferred from the intermediate transfer body 1007 to the recording medium 2 by a transfer roller 1008. At this time, the transfer is performed while the recording medium 2 is transported by a paper transport roller 1009.

[0014] 1 is a recording apparatus that performs recording using an intermediate transfer body 1007, but the recording apparatus equipped with the liquid ejection head of the present invention is not limited to this. That is, the recording apparatus may perform recording by ejecting liquid directly from the liquid ejection head 3 onto the recording medium 2 without using the intermediate transfer body 1007.

[0015] (liquid flow path) The liquid path will be described with reference to FIG. 2. FIG. 2 is a schematic diagram showing the liquid flow path of the recording device 1000. The two pressure adjustment mechanisms constituting the negative pressure control unit 230 are mechanisms (mechanical components with the same function as a so-called "back pressure regulator") that control the pressure fluctuations on the upstream side of the negative pressure control unit 230 to be within a certain range centered on a desired set pressure. Therefore, even if the flow rate of the liquid fluctuates due to a change in the recording duty when recording with the liquid ejection head 3, the pressure fluctuations on the upstream side (the liquid ejection unit 300 side) of the negative pressure control unit 230 are operated to be stable within a certain range centered on a preset pressure. In addition, the second circulation pump 1004 acts as a negative pressure source that reduces the pressure on the downstream side of the negative pressure control unit 230. The first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are arranged on the upstream side of the liquid ejection head 3, and the negative pressure control unit 230 is arranged in the liquid ejection head 3.

[0016] It is preferable to use the second circulation pump 1004 to pressurize the downstream side of the negative pressure control unit 230 via the liquid supply unit 220. This can suppress the effect of the head pressure of the buffer tank 1003 on the liquid ejection head 3, thereby expanding the range of options for the layout of the buffer tank 1003 in the recording apparatus 1000. The buffer tank 1003 is a tank that stores the liquid to be supplied to the liquid ejection head 3. Instead of the second circulation pump 1004, for example, a head tank arranged with a predetermined head difference with respect to the negative pressure control unit 230 can also be applied.

[0017] 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 high pressure setting side (H, FIG. 4(b)) and the low pressure side (L, FIG. 4(b)) are connected to the common supply flow channel 211 and the common recovery flow channel 212 in the liquid ejection unit 300 via the liquid supply unit 220, respectively. By making the pressure of the common supply flow channel 211 relatively higher than the pressure of the common recovery flow channel 212 by the two negative pressure adjustment mechanisms, an ink flow is generated that flows from the common supply flow channel 211 to the common recovery flow channel 212 via the individual supply flow channels 213a and the internal flow channels of each element substrate 10 (arrow). That is, the liquid recovered by the common recovery flow channel 212 circulates outside the element substrate 10 and flows to the common supply flow channel 211.

[0018] Since the negative pressure control unit 230 is disposed downstream of the liquid ejection head 3, there is little concern that dust or foreign matter generated from the negative pressure control unit 230 will flow into the head. In addition, the maximum flow rate required to supply liquid from the buffer tank 1003 to the liquid ejection head 3 can be reduced. The reason is as follows. The total flow rate in the common supply flow path 211 and the common recovery flow path 212 when circulating during standby for recording is defined as A. The value of A is defined as the minimum flow rate required to keep the temperature difference in the liquid ejection unit 300 within a desired range when adjusting the temperature of the liquid ejection head 3 during standby for recording. In addition, the ejection flow rate when ink is ejected from all ejection ports (not shown) of the liquid ejection unit 300 (during full ejection) is defined as F. Then, the amount of liquid supplied to the liquid ejection head 3 required during standby for recording is the flow rate A. And the amount of liquid supplied to the liquid ejection head 3 required during full ejection is the flow rate F. Then, the total value of the set flow rates of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002, i.e., the maximum value of the required supply flow rate, is the larger of A or F. Therefore, as long as the liquid ejection unit 300 of the same configuration is used, the maximum value of the required supply flow rate (A or F) becomes smaller. Therefore, the degree of freedom of the applicable circulation pump increases, and for example, it is possible to use a low-cost circulation pump with a simple configuration and reduce the load on a cooler (not shown) installed in the main body side path, which has the advantage of reducing the cost of the recording device main body. This advantage becomes greater as the value of A or F becomes relatively larger in the line head, and is more beneficial for line heads with a longer longitudinal length among line heads.

[0019] The first function can prevent excessive or insufficient pressure from being applied to the flow path downstream of the first circulating pumps 1001 and 1002 or upstream of the second circulating pump 1004. For example, if a malfunction of the first circulating pumps 1001 and 1002 occurs, an excessive flow rate or pressure may be applied to the liquid ejection head 3. This may cause liquid to leak from the ejection ports of the liquid ejection head 3 or cause breakage at each joint within the liquid ejection head 3. However, if a bypass valve is added to the first circulating pumps 1001 and 1002, even if excessive pressure occurs, the bypass valve 1010 opens to open the liquid path to the upstream side of each circulating pump, thereby preventing the above-mentioned trouble.

[0020] In addition, due to the second function, when the circulation drive is stopped, after the first circulation pumps 1001, 1002 and the second circulation pump 1004 are stopped, all the bypass valves 1010 are quickly opened based on a control signal from the main body side. This allows the high negative pressure (for example, several to several tens of kPa) in the downstream part of the liquid discharge head 3 (between the negative pressure control unit 230 and the second circulation pump 1004) to be released in a short time. When a volumetric pump such as a diaphragm pump is used as the circulation pump, a check valve is usually built into the pump. However, by opening the bypass valve, the pressure in the downstream part of the liquid discharge head 3 can be released from the downstream buffer tank 1003 side as well. Although the pressure in the downstream part of the liquid discharge head 3 can be released only from the upstream side, there is a pressure loss in the upstream flow path of the liquid discharge head and the flow path inside the liquid discharge head. Therefore, it takes time to release the pressure, and the pressure in the common flow path in the liquid discharge head 3 drops too much transiently, which may destroy the meniscus of the discharge port. By opening the bypass valve 1010 downstream of the liquid ejection head 3, pressure release downstream of the liquid ejection head is promoted, thereby reducing the risk of meniscus destruction at the ejection port.

[0021] 2 shows a recording apparatus in which liquid such as ink is circulated between the main tank 1006 and the liquid ejection head 3, but the present invention is not limited to this. For example, instead of circulating the ink, tanks may be provided on the upstream and downstream sides of the liquid ejection head, and the ink may flow from one tank to the other tank to cause the ink to flow.

[0022] A heating means 250 is disposed upstream of the element substrate 10 (upstream of the common supply flow path 211). Although details will be described later, by disposing the heating means 250, it is possible to increase the temperature of the liquid flowing through the common supply flow path 211, and to suppress deformation of the flow path member 210 (FIG. 3) in the transport direction of the recording medium.

[0023] (Liquid ejection head) The liquid ejection head 3 will be described with reference to Figs. 3 to 5. Fig. 3(a) is a perspective view of the liquid ejection head 3. Fig. 3(b) is an exploded perspective view of the liquid ejection head 3 (shield plate 132 is not shown). Fig. 4(a) is a side view of the liquid ejection head. Fig. 4(b) is a schematic diagram showing the flow of liquid inside the liquid ejection head 3. The circulation flow of liquid shown in Fig. 4(b) is the same as the circulation path shown in Fig. 2 in terms of circuitry, but Fig. 4(b) shows the actual flow of liquid within each component of the liquid ejection head 3. Note that some of the configuration has been simplified to facilitate understanding.

[0024] The liquid ejection head 3 has an element substrate 10 that ejects liquid from the ejection ports 13, and a flow path member 210 that has a flow path that supplies and recovers liquid to the element substrate 10. The liquid ejection head 3 is a so-called page-wide type head that has 36 element substrates 10 that are arranged linearly (in-line) in the longitudinal direction of the liquid ejection head 3. The element substrate 10 is formed with a pressure generating element 5 (FIG. 5) that generates pressure for ejecting liquid from the ejection ports 13 and a heating element 15 that heats the liquid to adjust the temperature of the liquid in the pressure chamber 7. The liquid in the pressure chamber 7 is heated by the heating element 15, and adjusted to a viscosity appropriate for ejection. The liquid ejection head 3 has a signal input terminal 91 for receiving a signal from the outside of the liquid ejection head 3, a power supply terminal 92 for receiving power, a shield plate 132 for protecting the side surface of the liquid ejection head 3, and the like.

[0025] The rigidity of the liquid ejection head 3 is ensured by the second flow path member 60 constituting the flow path member 210. The liquid ejection unit support part 81 is connected to both ends of the second flow path member 60, and this liquid ejection unit 300 is mechanically coupled to a carriage of the recording apparatus 1000 to position the liquid ejection head 3. The liquid supply unit 220 including the negative pressure control unit 230 and the electric wiring board 90 are coupled to the liquid ejection unit support part 81. A filter (not shown) is built into each of the two liquid supply units 220. The two negative pressure control units 230 are set to control pressure at different, relatively high and low negative pressures.

[0026] Next, the flow path member 210 of the liquid discharge unit 300 will be described in detail. The flow path member 210 is a laminate of a first flow path member 50 and a second flow path member 60, and distributes the liquid supplied from the liquid supply unit 220 to each discharge module 200. The flow path member 210 also functions as a flow path member for returning the liquid circulating from the discharge module 200 to the liquid supply unit 220. The second flow path member 60 of the flow path member 210 is a flow path member in which a common supply flow path 211 and a common recovery flow path 212 are formed, and has a function of mainly providing the rigidity of the liquid discharge head 3. For this reason, the material of the second flow path member 60 is preferably one having sufficient corrosion resistance against liquid and high mechanical strength. Specifically, stainless steel (SUS), Ti, alumina, etc. can be preferably used.

[0027] The first flow path member 50 is configured by arranging a plurality of members corresponding to the respective element substrates 10 adjacent to each other. With such a configuration, a plurality of element substrates 10 can be arranged on the first flow path member 50, and the length of the liquid ejection head 3 can be made to correspond to the width of the recording medium. For example, this is particularly suitable for use in a relatively long-scale liquid ejection head corresponding to a length of B2 size or larger. The individual supply flow paths 213a and the individual recovery flow paths 213b of the first flow path member 50 are fluidly connected to the element substrate 10.

[0028] In the element substrate 10, a flow path communicating with each ejection port 13 is formed, and a part or all of the supplied liquid can return through the ejection port 13 that is not ejecting. In addition, the common supply flow path 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery flow path 212 is connected to the negative pressure control unit 230 (low pressure side) via the liquid supply unit 220. Therefore, due to the pressure difference, ink flows from the common supply flow path 211 through the ejection port 13 of the element substrate 10 to the common recovery flow path 212. That is, ink flows from the upstream common supply flow path 211 through the element substrate 10 to the downstream common recovery flow path 212. Note that after the liquid is ejected from the element substrate 10, there is a possibility that the liquid may temporarily flow into the element substrate 10 from the common recovery flow path 212, but this is not considered as an upstream / downstream relationship regarding the flow of liquid in the present invention.

[0029] A set of common supply flow path 211 and common recovery flow path 212 extending in the longitudinal direction of the liquid ejection head 3 is provided in the long second flow path member 60. The flow direction of the liquid flowing in the common supply flow path 211 and the flow direction of the liquid flowing in the common recovery flow path 212 are opposite to each other, and a filter 221 is provided on the upstream side of each flow path to collect foreign matter entering from the liquid connection part 111, etc. In this way, by flowing the liquid in the common supply flow path 211 and the common recovery flow path 212 in the opposite directions to each other, heat exchange between the common supply flow path 211 and the common recovery flow path 212 is promoted, which is preferable in that the temperature gradient in the longitudinal direction in the liquid ejection head 3 is reduced. Note that in FIG. 2, the flow direction of the common supply flow path 211 and the common recovery flow path 212 are shown in the same direction to simplify the explanation.

[0030] A negative pressure control unit 230 is connected to the downstream side of each of the common supply flow path 211 and the common recovery flow path 212. In addition, the common supply flow path 211 has a branching portion into a plurality of individual supply flow paths 213a, and the common recovery flow path 212 has a branching portion into a plurality of individual recovery flow paths 213b. The individual supply flow paths 213a and the individual recovery flow paths 213b are formed in a plurality of first flow path members 50.

[0031] The negative pressure control units 230 indicated by H and L in FIG. 4(b) are units of the high pressure side (H) and the low pressure side (L). Each negative pressure control unit 230 is a back pressure type pressure adjustment mechanism set to control the pressure upstream of the negative pressure control unit 230 with relatively high (H) and low (L) negative pressures. The common supply flow path 211 is connected to the negative pressure control unit 230(H), and the common recovery flow path 212 is connected to the negative pressure control unit 230(L), so that a pressure difference occurs between the common supply flow path 211 and the common recovery flow path 212. Due to the pressure difference, the liquid flows from the common supply flow path 211 through the individual supply flow paths 213a, the element substrate 10, and the individual recovery flow paths 213b in this order to the common recovery flow path 212. The liquid in the element substrate 10 flows as indicated by the arrow 8 in FIG. 5.

[0032] FIG. 5(a) is a top view of the element substrate 10. FIG. 5(b) is an enlarged view of part B shown in FIG. 5(a). The liquid is supplied to the ejection port 13 through the individual supply flow path 213a. A heating element (hereinafter referred to as the main heater 5) is formed as a pressure generating element 5 directly below the ejection port 13. The main heater 5 is driven to cause film boiling of the liquid, and pressure is obtained for ejecting the liquid from the ejection port 13. A heating element 15 (hereinafter referred to as the sub-heater) that heats the liquid in order to control the viscosity of the liquid is formed in the vicinity of the ejection port 13 along the arrangement direction of the ejection port. The liquid is heated by driving the sub-heater 15, and the viscosity of the liquid can be controlled.

[0033] (First embodiment) The first embodiment of the present invention will be described with reference to Fig. 2 and Fig. 6. Fig. 6(a) is a schematic diagram showing the internal structure of a flow path member in a comparative example of this embodiment, and is a cross-sectional view taken along line GG in Fig. 4(a). Fig. 6(b) is a top view of the second flow path member 60 shown in Fig. 6(a) as viewed from the +Z direction, illustrating the internal structure so that the internal flow paths can be seen. Note that Fig. 6 is simplified for the purpose of explanation.

[0034] As described above, in the liquid ejection head 3 of this embodiment, the common supply flow path 211 and the common recovery flow path 212 extend in the longitudinal direction in the second flow path member 60. In other words, the common recovery flow path 211 and the common recovery flow path 212 are formed along the longitudinal direction of the flow path member. Liquid heated to a predetermined temperature by a heating element flows into the common recovery flow path 212 via the individual recovery flow paths 213b. As a result, the liquid temperature in the common recovery flow path 212 becomes higher than the liquid temperature in the common supply flow path 211, and the common recovery flow path side of the second flow path member 60 becomes relatively hot and the common supply flow path side becomes relatively cold. Due to this temperature gradient, as shown in FIG. 6(b), the common recovery flow path 212 side thermally expands more than the common supply flow path 211 side, so that the second flow path member 60 bends so as to protrude toward the common recovery flow path side in the recording medium transport direction. At this time, the higher the heating temperature of the liquid or the greater the flow rate of the liquid flowing into the common recovery channel 212, the higher the temperature of the common recovery channel 212 and the greater the amount of bending. Note that such bending increases as the length of the second flow channel member 60 increases, so there is a risk that bending will become more pronounced in a so-called page-wide type liquid ejection head having a length corresponding to the width of the recording medium 2.

[0035] Therefore, in the present invention, in order to suppress bending of the second flow path member 60 in the transport direction of the recording medium, a heating means 250 capable of heating the liquid is disposed upstream of the element substrate 10. Specifically, as shown in Fig. 2, the heating means 250 is disposed upstream of the common supply flow path 211 and between the buffer tank 1003 and the first circulation pump 1001. Note that, for example, a chiller, a heat pump, a heater, etc. can be used as the heating means, but other means may be used as long as they are capable of heating the liquid.

[0036] By providing the heating means 250, the liquid heated by the heating means 250 flows at least in the common supply flow path 211. Then, the heated liquid flows from the common supply flow path 211 through the element substrate 10 and is recovered to the common recovery flow path 212. Since the liquid already heated to a certain degree by the heating means 250 flows into the element substrate 10, the heater 5 provided in the element substrate 10 can obtain the bubbling pressure required for discharging the liquid with a small amount of heat generation. The small amount of heat generation from the heater 5 means that the temperature of the liquid in the common recovery flow path 212 into which the liquid from the element substrate 10 flows does not rise much. The fact that the temperature of the liquid in the common recovery flow path 212 does not rise much means that the temperature difference between the temperature of the liquid flowing in the common supply flow path 211 and the temperature of the liquid flowing in the common recovery flow path 212 can be suppressed from becoming large. In other words, the temperature gradient between the common supply flow path 211 and the common recovery flow path 212, which causes the flow path member 210 to deform in the transport direction of the recording medium, can be suppressed, and therefore deformation of the flow path member 210 can be suppressed.

[0037] 2 shows an example in which the heating means 250 is disposed upstream of the common supply flow path 211 and between the buffer tank 1003 and the second circulation pump 1004, but the present invention is not limited to this. That is, as long as the heating means 250 is disposed upstream of the element substrate 10, the temperature of the liquid flowing into the element substrate 10 can be preheated. Therefore, in the present invention, the heating means 250 may be disposed anywhere upstream of the element substrate 10.

[0038] The common supply flow path 211 and the common recovery flow path 212 are formed across the interior (inside) and exterior (outside) of the liquid discharge unit 300. It is more preferable to make the temperature of the liquid flowing through the common supply flow path 211 higher than the temperature of the liquid flowing through the common recovery flow path 212 at the outside (position C shown in FIG. 2) of the liquid discharge unit 300. Alternatively, it is preferable to make the temperature of the liquid flowing into the common supply flow path 211 (temperature of the liquid in the liquid supply unit) higher than the temperature of the liquid flowing into the common recovery flow path 212 (temperature of the liquid in the liquid supply unit). In this way, high-temperature liquid flows into the common supply flow path 211 in the liquid discharge unit 300, so that the amount of heat generated from the main heater 5 required for discharging the liquid can be reduced. Furthermore, even if the liquid is heated by the main heater 5, the warmed liquid flows through the common recovery flow path 212, which has a relatively low temperature. This makes it possible to reduce the difference in temperature between the liquid flowing in the common supply flow path 211 and the liquid flowing in the common recovery flow path 212, thereby further suppressing deformation of the flow path member 210 in the recording medium transport direction.

[0039] In order to make the liquid in the common supply flow path 211 and the liquid in the common recovery flow path 212 have different temperatures, the recording device may be provided with two heating means, one for the common supply flow path 211 and one for the common recovery flow path 212. In this case, however, it becomes necessary to separately manage the temperatures of the liquid flowing into the common recovery flow path 212 and the common supply flow path 211, which may complicate the device. Therefore, it is preferable to provide a heating means 250 at a position communicating with the common supply flow path 211, and to provide a desired temperature difference between the liquid in the common supply flow path 211 and the liquid in the common recovery flow path 212.

[0040] Second embodiment The second embodiment will be described. The same reference numerals are used for the same parts as those in the first embodiment, and the description will be omitted. In this embodiment, the flow rate of the liquid flowing through the common supply flow channel 211 is made larger than the flow rate of the liquid flowing through the common recovery flow channel 212 while the liquid flowing through the common supply flow channel 211 is heated by the heating means 250. In this way, when the cross-sectional areas of the common supply flow channel 211 and the common recovery flow channel 212 are the same (or approximately the same), the flow rate of the liquid flowing through the common supply flow channel 211 is larger than the flow rate of the liquid flowing through the common recovery flow channel 212. Therefore, the time required for the liquid that has flowed into the common supply flow channel 211 to flow out to the outside (the common recovery flow channel 212 or the liquid supply unit 220 (FIG. 2)) is shorter than the time required for the liquid that has flowed into the common recovery flow channel 212 to flow out to the outside (the liquid supply unit 220). In other words, the time that a certain volume of liquid stays in the common supply flow channel 211 is shorter than the time that it stays in the common recovery flow channel 212. As a result, when comparing the degree to which the liquid flowing through each flow path is cooled by the flow path member 210, the liquid flowing through the common supply flow path 211 is cooled less by the flow path member 210 than the liquid flowing through the common recovery flow path 212. That is, the temperature drop of the liquid in the common supply flow path 211 can be suppressed, and the temperature of the liquid in the common recovery flow path 212 can be lowered. By suppressing the drop in the temperature of the liquid in the common supply flow path 211, the amount of heat generated from the main heater 5 required for ejecting the liquid can be reduced. Furthermore, by lowering the temperature of the liquid in the common recovery flow path 212, even if the liquid is heated by the main heater 5, the heated liquid flows through the common recovery flow path 212, which has a relatively low temperature. As a result, the difference in temperature between the liquid flowing through the common supply flow path 211 and the liquid flowing through the common recovery flow path 212 can be made smaller, and therefore deformation of the flow path member 210 in the recording medium conveying direction can be further suppressed.

[0041] As a means for making the temperature of the liquid flowing in the common supply flow passage 211 at position C (FIG. 2) higher than the temperature of the liquid flowing in the common recovery flow passage 212 at position C, for example, the following means can be used. For example, the cross-sectional area of ​​the common supply flow passage 211 is set to be less than the cross-sectional area of ​​the common recovery flow passage 212, and the time for which the liquid flows through each flow passage is adjusted. In this way, the liquid temperature in the common supply flow passage 211 is greater than the liquid temperature in the common recovery flow passage 212. Here, the cross-sectional area of ​​the flow passage refers to the average value of the cross-sectional areas at 10 randomly selected points.

[0042] Alternatively, the thickness of the members of the flow path member 210 around the common supply flow path 211 may be made thicker and the thickness of the members around the common recovery flow path 212 may be made thinner, so that the degree to which the liquid is cooled in the common supply flow path 211 is relatively lower than that in the common recovery flow path 212. Here, the thickness of the members refers to the thickness from the flow path to the outer wall in the second flow path member 60. Alternatively, the members of the flow path member 210 may be appropriately adjusted to make the insulation rate around the common supply flow path 211 greater than the insulation rate around the common recovery flow path 212. That is, the insulation rate of the path from the heating means 250 to the common supply flow path is greater than the insulation rate of the path from the heating means to the common recovery flow path. With such a configuration, the liquid temperature in the common supply flow path can be made greater than the liquid temperature in the common recovery flow path. Another method is to make the flow path length of the common supply flow path 211 shorter than the flow path length of the common recovery flow path 212.

[0043] (Third embodiment) The third embodiment will be described with reference to Figs. 7 and 8. Note that the same reference numerals are used for the same parts as in the first embodiment, and the description will be omitted. Fig. 7 is a schematic diagram showing a cross section of a second flow path member 60 of this embodiment. Fig. 8 is a perspective view of the second flow path member 60 shown in Fig. 7(a). Note that Figs. 7 and 8 are simplified for the purpose of explanation.

[0044] In this embodiment, the liquid flowing through the common supply flow path 211 is heated by the heating means 250, as in the previous embodiments. The common supply flow path 211 and the common recovery flow path 212 are arranged so that at least a part of the common supply flow path 211 and at least a part of the common recovery flow path 212 overlap each other when viewed from the side where the ejection port opens. With this configuration, it is possible to further suppress the bending of the second flow path member 60 in the recording medium conveying direction. Note that the view from the side where the ejection port opens refers to the view seen through the internal structure of the head, such as the common supply flow path 211 and the common recovery flow path 212 of the second flow path member. When the common supply flow path 211 and the common recovery flow path 212 are arranged so that at least a part of the common supply flow path 211 and at least a part of the common recovery flow path 212 overlap each other, the above-mentioned temperature gradient occurs in a direction intersecting the recording medium conveying direction. This makes it possible to suppress the occurrence of a temperature gradient in the recording medium conveying direction, and therefore it is possible to further suppress the deformation of the second flow path member 60 in the recording medium conveying direction.

[0045] In addition, by adopting the configuration of this embodiment, a temperature gradient occurs in the second flow path member in the liquid ejection direction. This may cause the second flow path member 60 to bend in the liquid ejection direction. However, when the second flow path member 60 bends in the liquid ejection direction, the paper distance varies depending on the ejection port, but the position of the ejection port in the conveying direction of the recording medium is prevented from varying, so the effect on the recording quality is small. [Explanation of symbols]

[0046] 2 Recording media 3 Liquid ejection head 6, 15 Heating element 10 Element substrate 13 Outlet 60 Flow path member 211 Common supply channel 212 Common recovery channel 250 Heating means 1000 Recording Device

Claims

1. a plurality of element substrates each including an ejection port for ejecting liquid and a heating element for heating the liquid; a flow path member including a common supply flow path communicating with the plurality of element substrates and supplying liquid to the plurality of element substrates, and a common recovery flow path communicating with the plurality of element substrates and recovering liquid from the plurality of element substrates; A recording apparatus having a liquid ejection head including: the common supply flow path and the common recovery flow path are formed to be shifted from each other in a transport direction of the recording medium, a heating means for heating the liquid flowing in the common supply flow path, the heating means being disposed upstream of the element substrate; a heating means for heating the liquid flowing into the common supply flow passage so as to be higher in temperature than the liquid flowing into the common recovery flow passage;

2. 2. The recording apparatus according to claim 1, wherein the heating unit is disposed upstream of all of the plurality of element substrates.

3. 3. The recording apparatus according to claim 1, wherein the heating means is disposed outside the liquid ejection head.

4. the recording apparatus further includes a buffer tank that stores liquid to be supplied to the liquid ejection head; 4. The recording apparatus according to claim 1, wherein the heating means is disposed between the buffer tank and the liquid ejection head.

5. 5. The recording apparatus according to claim 1, wherein the liquid recovered by the common recovery flow path circulates outside the element substrate and flows into the common supply flow path.

6. 6. The recording apparatus according to claim 1, wherein a flow rate of the liquid flowing through the inlet of the common supply flow path is greater than a flow rate of the liquid flowing through the inlet of the common recovery flow path.

7. 7. The recording apparatus according to claim 1, wherein at least a part of the common supply flow path and at least a part of the common recovery flow path overlap each other when viewed from the side where the ejection ports are opened.

8. 8. The recording apparatus according to claim 1, wherein a cross-sectional area of ​​the common supply flow path is smaller than a cross-sectional area of ​​the common recovery flow path.

9. 9. The recording apparatus according to claim 1, wherein the length of the common supply flow path is shorter than the length of the common recovery flow path.

10. 10. The recording apparatus according to claim 1, wherein a thermal insulation rate of a path from the heating means to the common supply flow path is greater than a thermal insulation rate of a path from the heating means to the common recovery flow path.

11. 11. The recording apparatus according to claim 1, wherein the heating means is a chiller.

12. 12. The recording apparatus according to claim 1, wherein the heating element is a pressure generating element that heats liquid and generates pressure for ejecting the liquid from the ejection port.

13. 12. The recording apparatus according to claim 1, wherein the heating element is a sub-heater that heats the liquid and is separate from a pressure generating element that heats the liquid and generates pressure for ejecting the liquid from the ejection port.

14. 12. The recording apparatus according to claim 1, wherein the heating element is a pressure generating element that heats liquid to generate pressure for ejecting the liquid from the ejection port, and a sub-heater that heats liquid other than the pressure generating element.

15. 15. The recording apparatus according to claim 1, wherein the liquid ejection head is a page-wide type in which the plurality of ejection ports are arranged from one end to the other end of the recording medium in a direction intersecting a transport direction of the recording medium.

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