JP7463089B2 - Liquid ejection head - Google Patents

Description

The present invention relates to a liquid ejection head that ejects liquid.

A liquid ejection head ejects liquid from an ejection port to perform recording. When a certain amount of time has passed since the ejection of liquid has finished, the volatile components of the liquid remaining in the ejection port evaporate, and the viscosity of the liquid in the ejection port may increase. When the viscosity of the liquid in the ejection port increases, it becomes difficult for the liquid to be ejected from the ejection port, which may result in a decrease in the ejection speed of the ejected liquid or a situation in which the liquid is not ejected from the ejection port.

Patent Document 1 discloses a configuration in which a liquid ejection head is provided with a common supply flow path that supplies liquid to a pressure chamber that communicates with the ejection port, and a common recovery flow path that recovers liquid from the pressure chamber, thereby circulating liquid between the inside and outside of the pressure chamber. By circulating liquid between the inside and outside of the pressure chamber, it is possible to prevent the viscosity of the liquid in the ejection port from increasing.

JP 2019-043095 A

In the circulation mode described in Patent Document 1, if there is a heating element that heats the liquid in the pressure chamber, the liquid heated by the heating element will flow in the supply flow path located downstream of the pressure chamber. Therefore, the temperature of the liquid flowing in the common recovery flow path located downstream of the pressure chamber will be higher than the temperature of the liquid flowing in the common supply flow path located upstream of the pressure chamber. As a result, the temperature of the part around the common recovery flow path will be higher than the temperature of the part around the common supply flow path of the flow path member, resulting in a temperature bias (temperature gradient) within the flow path member. This temperature bias can cause deformation of the flow path member, which can affect the recording quality.

In view of the above problems, the present invention aims to provide a liquid ejection head that can suppress deformation of the flow path member.

The above-mentioned problems are solved by the present invention, which is described below. That is, the present invention is a liquid ejection head having an element substrate having a heating element for heating liquid in a pressure chamber communicating with an ejection port for ejecting liquid, a first flow path member in which a plurality of individual supply flow paths for supplying liquid to the pressure chambers and a plurality of individual recovery flow paths for recovering liquid from the pressure chambers are formed, and a second flow path member in which a common supply flow path connected to the plurality of individual supply flow paths and a common recovery flow path connected to the plurality of individual recovery flow paths are formed, the common supply flow path and the common recovery flow path are formed side by side in an arrangement direction that extends in the longitudinal direction of the second flow path member and intersects with the longitudinal direction, and either the common supply flow path or the common recovery flow path is disposed on both the side closest to one end and the side closest to the other end of the second flow path member in the arrangement direction, and two of the common supply flow paths and one of the common recovery flow paths are formed in the second flow path member .

The present invention provides a liquid ejection head that can suppress deformation of the flow path member.

FIG. FIG. 4 is a diagram showing a liquid circulation path of the recording apparatus. FIG. 2 is a diagram showing a liquid ejection head. FIG. 2 is a diagram showing a liquid ejection head. FIG. 13 is a diagram showing a second flow path member according to the related art. FIG. 4 is a view showing a second flow path member in the first embodiment. FIG. 11 is a view showing a second flow path member in the second embodiment. FIG. 13 is a view showing a second flow path member in a modified example of the second embodiment. FIG. 2 is a schematic diagram showing the configuration of an element substrate. FIG. 11 is a view showing a second flow path member in a modified example of the first embodiment.

The following describes an example of an embodiment of the present invention with reference to the drawings. Note that the longer the flow path member, the greater the deformation of the flow path member. Therefore, the present invention is particularly suitable for use with so-called page-wide heads that have flow path members longer than those of so-called serial type liquid ejection heads and correspond to the recording width of a recording medium such as paper. The following description uses a page-wide head as an example.

(Recording device)
The recording apparatus will be described with reference to FIG. 1. FIG. 1 shows a schematic diagram of an example of a recording apparatus equipped with a liquid ejection head 3 of the present invention. The recording apparatus shown in FIG. 1 is a recording apparatus that performs recording using an intermediate transfer body (intermediate transfer drum) 1007, but the recording apparatus equipped with the liquid ejection head 3 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. The recording apparatus 1000 shown in FIG. 1 ejects liquid from the liquid ejection head 3 onto the intermediate transfer body 1007 to form an image pattern (print pattern), and then transfers the image pattern to the recording medium 2. In the recording apparatus 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 recording image pattern is transferred by a transfer unit 1008 onto the recording medium 2 being transported by a paper transport roller 1009 .

(Circulation route)
The liquid circulation path will be described with reference to FIG. 2. FIG. 2 shows a schematic diagram of the liquid circulation 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 upstream of the negative pressure control unit 230 to be within a certain range centered on a desired set pressure. The second circulation pump 1004 acts as a negative pressure source that reduces the pressure downstream 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 disposed upstream of the liquid ejection head 3, and the negative pressure control unit 230 is disposed in the liquid ejection head 3.

The negative pressure control unit 230 operates to stabilize the pressure fluctuations on its upstream side (the liquid ejection unit 300 side) within a certain range centered on a preset pressure, even if the liquid flow rate fluctuates due to a change in the recording duty when recording with the liquid ejection head 3. It is preferable to pressurize the downstream side of the negative pressure control unit 230 via the liquid supply unit 220 using the second circulation pump 1004. In this way, the effect of the head pressure of the buffer tank 1003 on the liquid ejection head 3 can be suppressed, so that the range of options for the layout of the buffer tank 1003 in the recording device 1000 can be expanded. Instead of the second circulation pump 1004, for example, a head tank arranged with a predetermined head difference relative to the negative pressure control unit 230 can also be applied.

The negative pressure control unit 230 is equipped with two pressure adjustment mechanisms, each of which is set to a different control pressure. Of the two negative pressure adjustment mechanisms, the high pressure setting side (designated H) and the low pressure side (designated L) are connected to the common supply flow path 211 and the common recovery flow path 212 in the liquid ejection unit 300 via the liquid supply unit 220, respectively. By making the pressure of the common supply flow path 211 relatively higher than the pressure of the common recovery flow path 212 by the two negative pressure adjustment mechanisms, an ink flow is generated that flows from the common supply flow path 211 to the common recovery flow path 212 via the individual supply flow paths 213a and the internal flow paths of each element substrate 10 (arrow).

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 is small. 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 recording standby 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 the desired range when adjusting the temperature of the liquid ejection head 3 during recording standby. In addition, the ejection flow rate when ejecting ink from all ejection ports (not shown) of the liquid ejection unit 300 (at full ejection) is defined as F. Then, the amount of liquid supplied to the liquid ejection head 3 required during recording standby 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. In this case, 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 required supply flow rate, is the larger of A or F. Therefore, as long as the same configuration of the liquid ejection unit 300 is used, the maximum required supply amount (A or F) will be small. This increases the degree of freedom of the applicable circulation pump, and for example, it is possible to use a low-cost circulation pump with a simple configuration and reduce the load on the 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 is greater for line heads with a relatively large A or F value, and is more beneficial for line heads with a longer longitudinal length.

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

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 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 ejection 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 ejection head 3 can be released from the downstream buffer tank 1003 side as well. Although the pressure in the downstream part of the liquid ejection head 3 can be released only from the upstream side, there is a pressure loss in the upstream flow path of the liquid ejection head and the flow path inside the liquid ejection head. Therefore, it takes time to release the pressure, and the pressure in the common flow path in the liquid ejection head 3 drops too much transiently, which may destroy the meniscus of the ejection port. Opening the bypass valve 1010 downstream of the liquid ejection head 3 promotes pressure release downstream of the liquid ejection head, reducing the risk of meniscus destruction at the ejection port.

In FIG. 2, a recording device is shown 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 be caused to flow by flowing from one tank to the other tank.

(Liquid ejection head)
The liquid ejection head 3 will be described with reference to FIG. 3, FIG. 4, and FIG. 9. 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 view showing the flow of liquid inside the liquid ejection head 3. FIG. 4(c) is a perspective view showing a cross section taken along line G-G in FIG. 4(a). The flow of circulation 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 flow of liquid in each component of the actual liquid ejection head 3. Note that some of the configurations are simplified to facilitate understanding. FIG. 9 is a schematic view showing the configuration of an element substrate 10 that ejects liquid.

The liquid ejection head 3 is mainly composed of an element substrate 10 that ejects liquid from the ejection port 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 arranged in a straight line (in-line) in the longitudinal direction of the liquid ejection head 3. The element substrate 10 is formed with an energy generating element 5 (FIG. 9) that generates energy for ejecting liquid from the ejection port 13 and a heating element 6 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 6, and the viscosity is adjusted to an appropriate level 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 of the liquid ejection head 3, and the like.

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 connected to the carriage of the recording device 1000 to position the liquid ejection head 3. The liquid supply unit 220 equipped with the negative pressure control unit 230 and the electric wiring board 90 are connected 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.

Next, the flow path member 210 of the liquid ejection 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 ejection module 200. The flow path member 210 also functions as a flow path member for returning the liquid circulating from the ejection 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 the function of mainly providing the rigidity of the liquid ejection head 3. For this reason, the material of the second flow path member 60 is preferably one that has sufficient corrosion resistance against liquid and high mechanical strength. Specifically, stainless steel (SUS), Ti, alumina, etc. can be preferably used.

The first flow path member 50 is configured by arranging multiple members corresponding to each element substrate 10 adjacent to each other. With such a configuration, multiple 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, it is particularly suitable for relatively long-scale liquid ejection heads corresponding to B2 size or longer. The individual supply flow paths 213a (FIG. 4(c)) of the first flow path member 50 are fluidly connected to the element substrate 10, and the individual communication ports 53 (FIG. 4(c)) of the first flow path member 50 are fluidly connected to the communication ports 61 (FIG. 4(c)) of the second flow path member 60. The communication ports 61 of the second flow path member 60 are aligned and connected to the individual communication ports 53 of each first flow path member 50.

The element substrate 10 has flow paths that communicate with each ejection port 13, allowing some or all of the supplied liquid to circulate through ejection ports 13 that are not ejecting. 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, the pressure difference causes ink to flow from the common supply flow path 211 through the ejection ports 13 of the element substrate 10 to the common recovery flow path 212.

The liquid supply unit 220 is provided with a liquid connection section 111 and a filter 221, and the negative pressure control unit 230 is integrally formed below the liquid supply unit 220. This reduces the height distance between the negative pressure control unit 230 and the element substrate 10. This configuration reduces the number of flow path connections in the liquid supply unit 220, which not only improves reliability against leakage of recording liquid, but also has the advantage of reducing the number of parts and assembly steps.

In addition, since the head difference between the negative pressure control unit 230 and the surface on which the ejection ports 13 are formed is relatively small, the device can be suitably adapted to a recording device in which the inclination angle of the liquid ejection heads 3 differs for each liquid ejection head, as shown in FIG. 1. This is because the head difference can be reduced, and therefore the negative pressure difference applied to the ejection ports 13 of each element substrate 10 can be reduced even if multiple liquid ejection heads 3 are arranged at different inclination angles. Furthermore, the flow resistance therebetween is reduced by reducing the distance from the negative pressure control unit 230 to the element substrate 10. This also reduces the pressure loss difference due to changes in the liquid flow rate, enabling more stable negative pressure control to be performed.

In the long second flow path member 60, a set of common supply flow paths 211 and common recovery flow paths 212 extending in the longitudinal direction of the liquid ejection head 3 is provided. The flow direction of the liquid flowing through the common supply flow path 211 and 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 in the common supply flow path 211 and the common recovery flow path 212 is shown in the same direction to simplify the explanation.

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 within a plurality of first flow path members 50.

The negative pressure control units 230, indicated by H and L in FIG. 4(b), are units for 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 this 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. 9.

First Embodiment
The first embodiment of the present invention will be described with reference to FIG. 5, FIG. 6, and FIG. 10. FIG. 5(a) is a schematic diagram showing the internal structure of the second flow path member in a comparative example of this embodiment, and shows a cross section corresponding to the line G-G in FIG. 4(a). FIG. 5(b) is a top view of the second flow path member shown in FIG. 5(a) from the +Z direction, and is a schematic diagram illustrating the internal structure so that the internal flow path can be seen. FIG. 6(a) is a schematic diagram showing the internal structure of the second flow path member of this embodiment, and shows a cross section at the line G-G in FIG. 4(a). FIG. 6(b) is a top view of the second flow path member shown in FIG. 6(a) from the +Z direction, and is a schematic diagram illustrating the internal structure so that the internal flow path can be seen. Note that FIG. 5 and FIG. 6 are shown in a simplified manner with some of the configuration omitted for explanation. FIG. 10 is a front schematic diagram of the second flow path member showing a modified example of this embodiment shown in FIG. 6.

In order to explain this embodiment, a comparative example of this embodiment will be described first. As shown in FIG. 5, the common supply flow path 211 and the common recovery flow path 212 extend in the longitudinal direction (X direction) of the second flow path member 60. They are also formed side by side in the direction (Y direction) intersecting the longitudinal direction (X direction). In the common recovery flow path 212, a liquid heated by a heating element 6 that heats the liquid when passing through a pressure chamber 7 communicating with the discharge port flows. Therefore, the liquid flowing through the common recovery flow path 212 becomes hotter than the liquid flowing through the common supply flow path 211. As a result, the temperature near the common recovery flow path 212 is higher than the temperature near the common supply flow path 211 of the second flow path member, and a temperature bias occurs in the second flow path member depending on the location. Therefore, at both end portions in the lateral direction (Y direction) of the second flow path member, the temperature at one end is different from the temperature at the other end. As a result, as shown in FIG. 5(b), a deformation in the lateral direction occurs in the second flow path member 60. This deformation becomes larger as the second flow path member 60 becomes longer. In addition, the amount of deformation varies greatly depending on the material of the second flow path member 60; for example, general resins with low thermal conductivity will have little deformation due to temperature distribution bias, while alumina with high thermal conductivity will have a large deformation due to temperature distribution bias.

Therefore, in this embodiment, the same type of flow path is arranged on both outermost sides of the second flow path member 60 in the short side direction (Y direction) of the common supply flow path 211 and the common recovery flow path 212. That is, either the common supply flow path 211 or the common recovery flow path 212 is arranged on both ends in the arrangement direction (Y direction) of the common supply flow path 211 and the common recovery flow path 212. Specifically, in FIG. 6, two common supply flow paths 211 are arranged so as to sandwich one common recovery flow path 212 in the short side direction of the second flow path member 60. With this configuration, the deviation of the temperature distribution at one end side and the other end side in the short side direction (Y direction) of the second flow path member 60 is suppressed, and deformation of the second flow path member 60 can be suppressed. As a result, a liquid ejection head that enables high-quality recording can be provided.

Furthermore, by setting the cross-sectional area of the flow path according to the temperature difference between the liquids flowing through the common supply flow path 211 and the common recovery flow path 212, the effect can be more favorably achieved. For example, as shown in FIG. 10(a), the cross-sectional area of the short cross section of the common recovery flow path 212, through which a liquid with a higher temperature than the liquid flowing through the common supply flow path 211 flows, is made smaller than the cross-sectional area of the short cross section of the common supply flow path 211. As a result, the area through which the high-temperature liquid flows is reduced, so that the temperature around the common recovery flow path 212 with the reduced cross-sectional area is lower than the temperature around the common recovery flow path 212 when the cross-sectional area of the flow path is not reduced. As a result, the temperature of the part around the common recovery flow path 212 of the flow path member 60 approaches the temperature of the part around the common supply flow path 211. Therefore, by configuring in this way, the temperature difference between both ends and the center in the short direction of the second flow path member 60 can also be reduced, so that deformation in the short direction of the second flow path member 60 can be further suppressed. That is, the cross-sectional area of the flow path sandwiched between the flow paths at both ends is set so as to approach the temperature of the liquid flowing through the flow paths formed at both ends in the short direction of the second flow path member 60. In other words, when the flow paths formed at both ends in the short direction of the second flow path member 60 are common recovery flow paths, the cross-sectional area of the common supply flow path sandwiched between the common recovery flow paths is increased so that the temperature of the components around the common supply flow path becomes higher.

As shown in FIG. 10(b), the common supply flow path 211 and the common recovery flow path 212 formed in the second flow path member 60 may be formed so as to be biased toward either end side in the arrangement direction (Y direction) of the second flow path member. Furthermore, as shown in FIG. 10(c), each flow path may not be formed at the same height, that is, the center of gravity of each flow path may not be formed at the same height (position in the Z direction (direction perpendicular to the extension direction and arrangement direction of each flow path)). However, since the deformation of the member can be suppressed as the temperature distribution of the second flow path member becomes more uniform, it is preferable that the second flow path member is formed so that at least a part of the flow paths overlap each other when viewed from the arrangement direction (Y direction). Furthermore, as shown in FIG. 6, it is more preferable that each flow path is formed at equal intervals in the arrangement direction and at the same height. Note that, here, equal intervals means that the flow paths are formed at substantially the same intervals, and is considered to be equal intervals when the difference in intervals is only due to the deviation in intervals caused by manufacturing errors. Similarly, the same height means that the flow paths are substantially the same height, and is considered to be equal intervals when the only deviation is due to manufacturing errors.

Moreover, it is more preferable that the length of the flow path arranged at one end in the arrangement direction (Y direction) of the common supply flow path 211 and the common recovery flow path 212 is the same as the length of the flow path arranged at the other end. By having the same lengths of the flow paths arranged at one end and the other end, the temperature at one end and the temperature at the other end also become closer to the same temperature, and deformation of the second flow path member 60 can be further suppressed. Here, "the lengths of the flow paths are the same" means that the lengths are substantially the same. Therefore, even if there is a difference in length due to manufacturing errors, the lengths are considered to be the same if the design dimensions are the same.

The common recovery flow path 212 is formed continuously in the longitudinal direction of the second flow path member 60, and therefore has a large effect on the temperature distribution of the second flow path member 60. Therefore, in the present invention, attention is focused on the temperature difference between the common supply flow path 211 and the common recovery flow path 212, which are formed continuously in the longitudinal direction of the second flow path member.

For the sake of explanation, in the above description, the temperature of the components around the common recovery flow path 212 increases as the liquid heated by the heating element 6 that adjusts the viscosity of the liquid flows through the common recovery flow path 212. However, the temperature of the liquid flowing through the common recovery flow path 212 may increase even if the heating element 6 that adjusts the viscosity of the liquid is not provided. That is, when a heating element that heats the liquid to the point of film boiling and generates a bubbling pressure is used as the energy generating element 5, the temperature of the liquid in the pressure chamber 7 increases, and the temperature of the liquid flowing through the common recovery flow path 212 also increases. Therefore, the present invention can be suitably used when at least one of the heating element 6 or the heating element that causes film boiling of the liquid as the energy generating element is provided on the element substrate 10.

Second Embodiment
The second embodiment will be described with reference to FIG. 7 and FIG. 8. The same reference numerals are used for the same parts as those in the first embodiment, and the description will be omitted. FIG. 7(a) is a perspective schematic diagram of the second flow path member, showing a cross section at the line G-G in FIG. 4(a). FIG. 7(b) is a side schematic diagram in FIG. 7(a). FIG. 7(c) is a front schematic diagram in FIG. 7(a). FIG. 8(a) is a perspective schematic diagram of the second flow path member in a modified example of the second embodiment, showing a cross section at the line G-G in FIG. 4(a). FIG. 8(b) is a front schematic diagram in FIG. 8(a). FIG. 8(c) is a side schematic diagram in FIG. 8(a). In FIG. 7(a) to (c) and FIG. 8(a) to (c), some of the configurations are simplified to facilitate understanding.

In the second embodiment, the common supply flow path 211 and the common recovery flow path 212 are arranged at both outermost positions in the vertical direction (Z direction) of the second flow path member 60. That is, this embodiment differs from the first embodiment in that the arrangement direction of the common supply flow path 211 and the common recovery flow path 212 is the vertical direction (Z direction) of the flow path member 60. In FIG. 7, two common supply flow paths 211 are arranged to sandwich one common recovery flow path 212 in the Z direction. With this configuration, the temperature gradient of the common supply flow path 211 and the common recovery flow path 212 can be reduced, and deformation of the second flow path member 60 in the vertical direction can be suppressed. Also, as in the first embodiment, by changing the flow path aspect ratio according to the temperature difference of the liquid flowing through the common supply flow path 211 and the common recovery flow path 212 (see FIG. 7(c)), deformation of the flow path member 60 can be further suppressed.

In addition, in this embodiment, as shown in FIG. 8, the second flow path member 60 may be formed by stacking a plurality of laminated members 60a-g in the Z direction. Specifically, the laminated members 60b, 60d, and 60f in which the through holes 4 are formed and the flat plates 60a, 60c, 60e, and 60g are alternately stacked. This configuration has the effect of reducing manufacturing costs and improving component accuracy compared to the second flow path member 60 shown in FIG. 7(a). In addition, any joining method such as adhesion or welding can be suitably used between the laminated members. Note that the second flow path member may be formed by stacking a plurality of members 60a-g in the Y direction. In that case, the second flow path member 60 in which the common supply flow path 211 and the common recovery flow path 212 are arranged side by side in the Y direction as shown in FIG. 6 is formed. Similarly, the effect of reducing manufacturing costs and improving component accuracy can be obtained.

REFERENCE SIGNS 3 Liquid ejection head 6 Heating element 7 Pressure chamber 10 Element substrate 13 Ejection port 50 First flow path member 60 Second flow path member 211 Common supply flow path 212 Common recovery flow path 213a Individual supply flow path 213b Individual recovery flow path

Claims (9)

an element substrate having a heating element for heating a liquid in a pressure chamber communicating with an ejection port for ejecting the liquid;
a first flow path member in which a plurality of individual supply flow paths that supply liquid to the pressure chambers and a plurality of individual recovery flow paths that recover liquid from the pressure chambers are formed;
a second flow path member in which a common supply flow path connected to the plurality of individual supply flow paths and a common recovery flow path connected to the plurality of individual recovery flow paths are formed;
In a liquid ejection head having
the common supply flow path and the common recovery flow path are formed to extend in a longitudinal direction of the second flow path member and to be aligned with each other in an arrangement direction that is a direction intersecting the longitudinal direction,
one of the common supply flow path and the common recovery flow path is disposed on both a side closest to one end of the second flow path member and a side closest to the other end of the second flow path member in the arrangement direction,
The liquid ejection head according to claim 1, wherein the second flow path member is formed with two of the common supply flow paths and one of the common recovery flow paths. an element substrate having a heating element for heating a liquid in a pressure chamber communicating with an ejection port for ejecting the liquid;
a first flow path member in which a plurality of individual supply flow paths that supply liquid to the pressure chambers and a plurality of individual recovery flow paths that recover liquid from the pressure chambers are formed;
a second flow path member in which a common supply flow path connected to the plurality of individual supply flow paths and a common recovery flow path connected to the plurality of individual recovery flow paths are formed;
In a liquid ejection head having
the common supply flow path and the common recovery flow path are formed to extend in a longitudinal direction of the second flow path member and to be aligned with each other in an arrangement direction that is a direction intersecting the longitudinal direction,
one of the common supply flow path and the common recovery flow path is disposed on both a side closest to one end of the second flow path member and a side closest to the other end of the second flow path member in the arrangement direction,
The liquid ejection head according to claim 1, wherein the arrangement direction is a direction intersecting the longitudinal direction and a lateral direction of the second flow path member. an element substrate having a heating element for heating a liquid in a pressure chamber communicating with an ejection port for ejecting the liquid;
a first flow path member in which a plurality of individual supply flow paths that supply liquid to the pressure chambers and a plurality of individual recovery flow paths that recover liquid from the pressure chambers are formed;
a second flow path member in which a common supply flow path connected to the plurality of individual supply flow paths and a common recovery flow path connected to the plurality of individual recovery flow paths are formed;
In a liquid ejection head having
the common supply flow path and the common recovery flow path are formed to extend in a longitudinal direction of the second flow path member and to be aligned with each other in an arrangement direction that is a direction intersecting the longitudinal direction,
one of the common supply flow path and the common recovery flow path is disposed on both a side closest to one end of the second flow path member and a side closest to the other end of the second flow path member in the arrangement direction,
A liquid ejection head characterized in that the common supply flow path is arranged at one end and the other end in the arrangement direction, the common recovery flow path is arranged between the common supply flow paths arranged at the one end and the other end, and the cross-sectional area of the common recovery flow path is smaller than the cross-sectional area of the common supply flow path. 4. The liquid ejection head according to claim 1, wherein a flow direction of the liquid flowing through the common supply flow channel is opposite to a flow direction of the liquid flowing through the common recovery flow channel. 5. The liquid ejection head according to claim 1, wherein the second flow path member is formed by alternately laminating a member having a through hole and a flat plate. 6. The liquid ejection head according to claim 1, wherein the heating element is an element for adjusting the temperature of the liquid in the pressure chamber. the heating element is an element for adjusting a temperature of the liquid in the pressure chamber,
6. A liquid ejection head according to claim 1 , further comprising an energy generating element, separate from said element, for heating the liquid to cause film boiling and generating energy for ejecting the liquid from said ejection port. 8. The liquid ejection head according to claim 1, wherein the common supply flow path and the common recovery flow path are formed at equal intervals in the arrangement direction. the common supply flow path and the common recovery flow path at least partially overlap each other when the second flow path member is viewed from the arrangement direction,
The center of gravity of the common supply flow passage and the center of gravity of the common recovery flow passage are
9. The liquid ejection head according to claim 1, wherein the first and second electrodes are formed at the same position in both directions perpendicular to each other .

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