Liquid discharge head

Abstract

To provide a liquid discharge head that can effectively heat liquid in a flow passage even if heat quantity (electric power) of a heating member is increased.SOLUTION: A liquid discharge head includes: a flow passage member 100 that has a flow passage 105 through which liquid flows; and a heating member 113 that is mounted on an outer wall surface 200 of the flow passage member 100 and heats liquid in the flow passage 105. The heating member 113 has: a first layer 210 that includes a heat generating section 130 generating heat by energization; a second layer 211 that includes a first conductive section 131 facing one surface 130a of the heat generating section 130; and a first coupling section 132 that electrically couples the heat generating section 130 and the first conductive section 131.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head that ejects liquid. [Background technology]

[0002] In order to maintain recording quality in an inkjet recording device equipped with a liquid ejection head that ejects liquid such as ink, it is necessary to keep the amount of liquid ejected per droplet (hereinafter referred to as droplet volume) constant. Maintaining a constant droplet volume is effective in keeping the viscosity of the liquid inside the flow path of the liquid ejection head at an appropriate level. Generally, the viscosity of a liquid is highly temperature-dependent, so it is effective to keep the temperature of the liquid within a specified temperature range. Patent Document 1 describes a recording head in which a heater, which is a heating member, is attached to the outer wall surface of a manifold, which is a flow path member. In this recording head, the heater generates heat to heat the liquid in the flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5958365 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the recording head described in Patent Document 1 has the following problems. The temperature suitable for ejecting a liquid may vary depending on the liquid's components. When using a liquid with a high temperature suitable for ejection, in order to heat the liquid to a predetermined temperature within a predetermined time, it is necessary to increase the power supplied to the heater and increase the amount of heat applied to the liquid per unit time. However, increasing the amount of heat from the heater increases the temperature range of the heater's spatial temperature distribution, making it difficult to effectively heat the liquid in the flow path.

[0005] An object of the present invention is to provide a liquid ejection head that can effectively heat the liquid in the flow path even if the heat quantity (electric power) of the heating member is increased. [Means for solving the problem]

[0006] In order to achieve the above object, a liquid ejection head according to one aspect of the present invention comprises a flow path member having a flow path through which liquid flows, and a heating member attached to the outer wall surface of the flow path member and heating the liquid in the flow path, wherein the heating member comprises a first layer including a heat generating portion that generates heat when electricity is passed through it, a second layer including a first conductive portion that faces one side of the heat generating portion, and a first connecting portion that electrically connects the heat generating portion to the first conductive portion. [Effects of the Invention]

[0007] According to the present invention, the liquid in the flow path can be effectively heated even if the amount of heat (electric power) of the heating member is increased. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a liquid ejection head according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the liquid ejection head shown in FIG. [Figure 3] FIG. 2 is a schematic diagram illustrating an example of a heating member. [Figure 4] FIG. 4 is a cross-sectional view of the heating member shown in FIG. [Figure 5] 5 is a schematic diagram showing the structure of a heat generating portion and a first conductive portion shown in FIG. 4. FIG. [Figure 6] FIG. 5 is a cross-sectional view of the first coupling portion shown in FIG. 4. [Figure 7] 4 is a schematic diagram showing a path of a current flowing through the heating member shown in FIG. 3. FIG. [Figure 8] 4 is a schematic diagram showing a heat transfer path of the heating member shown in FIG. 3. FIG. [Figure 9] FIG. 10 is a schematic diagram for explaining the configuration of a heating member of a comparative example. [Figure 10]FIG. 10 is a cross-sectional view of the heating member shown in FIG. [Figure 11] FIG. 11 is a plan view of the heat generating portion shown in FIG. [Figure 12] FIG. 10 is a diagram for explaining a one-dimensional model analysis of a heating member. [Figure 13] 13 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in FIG. 12 is applied to the heating member shown in FIG. [Figure 14] 13 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in FIG. 12 is applied to the heating member shown in FIG. [Figure 15] FIG. 10 is a schematic diagram illustrating an example of a heating member of a liquid ejection head according to a second embodiment of the present invention. [Figure 16] FIG. 16 is a cross-sectional view of the heating member shown in FIG. [Figure 17] 16 is a schematic diagram showing a path of a current flowing through the heating member shown in FIG. 15. FIG. [Figure 18] 16 is a schematic diagram showing a heat transfer path of the heating member shown in FIG. 15. FIG. [Figure 19] 16 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in FIG. 12 is applied to the heating member shown in FIG. 15. FIG. [Figure 20] FIG. 10 is a schematic diagram showing a first modified example of the liquid ejection head according to the second embodiment of the present invention. [Figure 21] FIG. 10 is a schematic diagram showing a second modified example of the liquid ejection head according to the second embodiment of the present invention. [Figure 22] 17 is a cross-sectional view of the first coupling portion and the second coupling portion shown in FIG. 16. FIG. [Figure 23] 5 is a schematic diagram for explaining the relationship in size between a heat generating portion and a first conductive portion. FIG. [Figure 24] FIG. 2 is a schematic diagram showing a first modified example of the liquid ejection head according to the first embodiment of the present invention. [Figure 25] FIG. 25 is a cross-sectional view of the heating element shown in FIG. 24. [Figure 26] 25 is a schematic diagram showing a heat transfer path of the heating member shown in FIG. 24. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiments are merely examples and are not intended to limit the scope of the present invention to the embodiments.

[0010] (First embodiment) Fig. 1 is a perspective view of a liquid ejection head according to a first embodiment of the present invention. Fig. 2 is an exploded perspective view of the liquid ejection head shown in Fig. 1. In Fig. 2, both solid and dashed arrows indicate paths along which liquid such as ink flows. 1 and 2, the liquid ejection head 10 has two heating members 111 and 112, a flow path member 100 consisting of first to third flow path members 102 to 104, and four recording chips 107a, 107b, 108a, and 108b.

[0011] The first flow path member 102 is joined to one surface of the second flow path member 103, and the third flow path member 104 is joined to the other surface of the second flow path member 103. When the first to third flow path members 102 to 104 are joined together, four flow paths 105a, 105b, 106a, and 106b are formed. The flow path 105a communicates with the recording chip 107a, and the flow path 105b communicates with the recording chip 107b. The flow path 106a communicates with the recording chip 108a, and the flow path 106b communicates with the recording chip 108b.

[0012] Surfaces 200a and 200b of the first flow path member 102 opposite to the side joined to the second flow path member 103 form the outer wall surface 200 of the flow path member 100. Surface 200a is adjacent to flow paths 105a and 105b and extends in the Y direction. Surface 200b is adjacent to flow paths 106a and 106b and extends in the Y direction.

[0013] Liquids 101a and 101b are supplied to the liquid ejection head 10 from supply channels (not shown). Liquid 101a is supplied to recording chips 107a and 108b via flow channels 105a and 106b, and liquid 101b is supplied to recording chips 107b and 108a via flow channels 105b and 106a. Recording chip 107a ejects droplet 109a, and recording chip 107b ejects droplet 109b. Recording chip 108a ejects droplet 110a, and recording chip 108b ejects droplet 110b.

[0014] The heating members 111 and 112 can be configured, for example, by film heaters. The heating member 111 is T-shaped and includes heating portions 111a and 111b extending in the X direction and a terminal 111c for electrical conduction. When electrical current is applied to the terminal 111c, current flows through the heating portions 111a and 111b, generating heat. The heating member 112 is also T-shaped and includes heating portions 112a and 112b extending in the X direction and a terminal 112c for electrical conduction. When electrical current is applied to the terminal 112c, current flows through the heating portions 112a and 112b, generating heat.

[0015] The heating member 111 has heating portions 111a and 111b attached to the surface 200a of the outer wall surface 200, and can heat the liquid flowing through the flow paths 105a and 105b. Specifically, when current is applied, the heating portions 111a and 111b generate heat, which heats the first flow path member 102, and the second flow path member 103, the third flow path member 104, and the recording chips 107a and 107b are heated by thermal conduction. As a result, the liquid flowing through the flow paths 105a and 105b is also heated by thermal conduction.

[0016] The heating member 112 has heating portions 112a and 112b attached to the surface 200b of the outer wall surface 200, and can heat the liquid flowing through the flow paths 106a and 106b. Specifically, when current is applied, the heating portions 112a and 112b generate heat, which heats the first flow path member 102, and the second flow path member 103, the third flow path member 104, and the recording chips 108a and 108b are heated by thermal conduction. As a result, the liquid flowing through the flow paths 106a and 106b is also heated by thermal conduction.

[0017] Next, a detailed description will be given of the structure of the heating members 111 and 112. Because the heating members 111 and 112 have the same structure, in the following description, the heating members 111 and 112 will be referred to as heating member 113, and the configuration of heating member 113 will be described in detail.

[0018] Fig. 3 is a schematic diagram for explaining an example of the configuration of the heating member 113. Referring to Fig. 3, the flow path member 100 includes a flow path 105, and the heating member 113 is attached to the outer wall surface 200 of the flow path member 100. The flow path 105 corresponds to the flow paths 105a, 105b, 106a, and 106b shown in Fig. 2. A liquid 115 flows through the flow path 105.

[0019] The heating member 113 has a heat generating portion 130, a first conductive portion 131, and a first coupling portion 132. The heat generating portion 130 corresponds to the heating portions 111a and 111b shown in FIG. 2 and is formed, for example, by a film heater. The heat generating portion 130 extends in the X direction and has a terminal 140-2 at one end in the longitudinal direction. The terminal 140-2 is connected to the positive terminal of the power source 118. These terminals 140-1 and 140-2 are a pair of terminals for supplying electricity.

[0020] The first conductive part 131 is disposed opposite the heat generating part 130 and extends in the X direction. A terminal 140-1 is provided at one longitudinal end of the first conductive part 131. The terminal 140-1 is connected to the negative terminal of the power supply 118. The first coupling portion 132 electrically couples the heat generating portion 130 and the first conductive portion 131. Here, the other longitudinal end of the heat generating portion 130 and the other longitudinal end of the first coupling portion 132 are electrically connected via the first coupling portion 132. The material of the first conductive portion 131 and the first coupling portion 132 can be, for example, copper (Cu).

[0021] Fig. 4 is a cross-sectional view of the heating member 113 shown in Fig. 3. Fig. 4 schematically shows the cross-sectional structure of the heating member 113 in the short side direction (Y direction). 4, the heating member 113 has a multi-layer structure and includes a first layer 210 including the heat generating portion 130 and a second layer 211 including the first conductive portion 131. The heat generating portion 130 has a first surface 130a and a second surface 130b opposite the first surface 130a, and generates heat from both the first surface 130a and the second surface 130b when electricity is applied. The second surface 130b of the heat generating portion 130 is fixed to the outer wall surface 200 of the flow path member 100 via an adhesive member 135 and an insulating member 136. Of the first surface 130a and the second surface 130b, the surface located on the side of the first conductive portion 131 is referred to as "one surface."

[0022] First conductive portion 131 faces first surface (one surface) 130a of heat generating portion 130. First conductive portion 131 is sandwiched between insulating members 137 and 138, and the side of insulating member 137 is fixed to first surface 130a of heat generating portion 130. First conductive portion 131 acts to equalize the heat generated on first surface 130a of heat generating portion 130.

[0023] Fig. 5 is a diagram schematically showing the structures of the heat generating part 130 and the first conductive part 131 shown in Fig. 4. Fig. 5(a) is a plan view of the heat generating part 130, and Fig. 5(b) is a plan view of the first conductive part 131. As shown in FIG. 5(a), the heat generating unit 130 has a heat generating pattern 130-1. The heat generating pattern 130-1 is formed by folding back a wiring multiple times at regular intervals to form a planar heat generating unit, with a terminal 140-2 provided at one end of the wiring and the other end of the wiring electrically connected to the first coupling unit 132. For example, CuNi or the like can be used as the wiring material for the heat generating pattern 130-1. Note that the heat generating pattern 130-1 is not limited to the pattern shown in FIG. 5(a). The heat generating pattern 130-1 may be formed in any pattern as long as it can form a planar heat generating unit.

[0024] As shown in FIG. 5(b), the first conductive portion 131 has a uniform pattern 131-1. The uniform pattern 131-1 has a uniform shape, which is effective in equalizing the heat generated on the first surface 130a of the heat generating portion 130. One of the longitudinal ends of the uniform pattern 131-1 is provided with a terminal 140-1, and the other end is electrically connected to the first coupling portion 132. The purpose of the uniform pattern 131-1 is to equalize the heat generated in the heat generating portion 130 and to form part of the current-carrying circuit of the heat generating portion 130. For this purpose, it is preferable to use copper (Cu), for example, as the material for the uniform pattern 131-1. The pattern of the first conductive portion 131 is not limited to the pattern shown in the figure. The first conductive portion 131 may be formed in any pattern as long as it can equalize the heat generated in the heat generating portion 130 and form part of the current-carrying circuit.

[0025] 6 is a cross-sectional view of the first coupling portion 132 shown in FIG. 6. As shown in FIG. 6, the first coupling portion 132 has a through hole 132-1 and a metal thin film 132-2 formed on the inner surface of the through hole 132-1. The through hole 132-1 penetrates the first layer 210, the insulating member 137, and the second layer 211. The heat generating portion 130 of the first layer 210 is electrically connected to the first conductive portion 131 of the second layer 211 via the metal thin film 132-2.

[0026] Here, a brief description will be given of a method for forming the first coupling portion 132 shown in Fig. 6. First, the heat generating portion 130, the insulating member 137, and the first conductive portion 131 are laminated, and a through hole 132-1 is formed in the portion that will become the coupling portion. For example, the through hole 132-1 can be formed by punching with a mold or drilling. After the through hole 132-1 is formed, the inner surface of the through hole 132-1 is plated to form a thin metal film 132-2.

[0027] Next, the path of the current flowing through the heating member 113 will be described. Fig. 7 is a schematic diagram showing the path of the current flowing through the heating member 113. In Fig. 7, the solid arrows indicate the path of the current flow. As shown in FIG. 7, current is supplied from the power source 118 to the terminal 140-2 of the first conductive portion 131. In the first conductive portion 131, the current supplied to the terminal 140-2 flows through the uniform pattern 131-1 shown in FIG. 5(b) toward the first coupling portion 132. The current then flows from the first coupling portion 132 into the heat generating portion 130. In the heat generating portion 130, the current flowing from the first coupling portion 132 flows through the heat generating pattern 130-1 shown in FIG. 5(a) toward the terminal 140-1. The current then returns to the power source 118 via the terminal 140-1. In this way, the heat generating portion 130, the first conductive portion 131, and the first coupling portion 132 form a current-carrying circuit (a closed circuit for power supply).

[0028] Next, the heat transfer path of the heating member 113 will be described. Fig. 8 is a schematic diagram showing the heat transfer path of the heating member 113. In Fig. 8, the outline arrow a and the solid arrows b and c indicate the transfer of heat. The heat generated by the heat generating unit 130 moves to both the flow path member 100 side (the side of surface 130b shown in FIG. 4) and the first conductive member 131 side (the side of surface 130a shown in FIG. 4). On the first conductive member 131 side of the heat generating unit 130, the heat moves to the first conductive member 131 via the insulating member 136 shown in FIG. 4 (white arrow a) and also via the first coupling portion 132 (solid arrow b). Here, the temperature of the surface 130a of the heat generating unit 130 is highest in the center, and the white arrow a indicates the movement of heat in this center. In the first conductive member 131, the heat from the center of the surface 130a is diffused in the in-plane direction (solid arrow c). In this way, the first conductive member 131 acts to equalize the heat generated on the first surface 130a of the heat generating unit 130.

[0029] According to the liquid ejection head 10 of the present embodiment described above, the liquid 115 in the flow path 105 of the flow path member 100 is heated using the heating member 113 as shown in Figures 3 to 8. Even if the amount of heat generated by the heat generating section 130 is increased by increasing the power supplied from the power source 118, the first conductive member 131 distributes the heat evenly, making it possible to heat the liquid 115 effectively.

[0030] The following will specifically explain the above-mentioned effects of the heating member 113. Here, the problems and effects will be explained in detail in comparison with a heating member of a comparative example.

[0031] 9 is a schematic diagram illustrating the configuration of a heating member of a comparative example. As shown in FIG. 9, a heating member 117 of the comparative example is attached to the outer wall surface 200 of a flow path member 100. The flow path member 100 is the same as that shown in FIG. 3. The heating member 117 has terminals 119-1 and 119-2. The terminal 119-1 is connected to the negative terminal of a power source 118, and the terminal 119-2 is connected to the positive terminal of the power source 118.

[0032] Fig. 10 is a cross-sectional view of the heating member 117 shown in Fig. 9. Fig. 10 schematically shows the cross-sectional structure of the heating member 117 in the short-side direction (Y direction). 10, the heating member 117 includes a heat generating portion 120. The heat generating portion 120 has a first surface 120a and a second surface 120b opposite to the first surface 120a, and generates heat from both the first surface 120a and the second surface 120b when electricity is applied. The heat generating portion 120 is sandwiched between insulating members 122 and 123. The second surface 120b of the heat generating portion 120 is fixed to the outer wall surface 200 of the flow path member 100 via an adhesive member 121 and an insulating member 122.

[0033] Fig. 11 is a plan view of the heat generating part 120 shown in Fig. 10. As shown in Fig. 11, the heat generating part 120 has a heat generating pattern 120-1. The heat generating pattern 120-1 is formed by folding back a wiring multiple times at regular intervals to form a planar heat generating part, with a terminal 119-1 provided at one end of the wiring and a terminal 119-2 provided at the other end of the wiring. The wiring material of the heat generating pattern 120-1 can be, for example, CuNi.

[0034] Current is supplied from power supply 118 to terminal 119-2 of heat generating unit 120. In heat generating unit 120, the current supplied to terminal 119-2 flows through heat generating pattern 120-1 shown in Fig. 11 toward terminal 119-1. The current then returns to power supply 118 via terminal 119-1. In this way, heat generating unit 120 forms a current-carrying circuit (a closed circuit for power supply), and generates heat when a current flows through heat generating pattern 120-1.

[0035] Here, we will consider the spatial temperature distribution by modeling the heating member 117 shown in Fig. 9. Here, we assume that the thickness direction (Z direction) and depth direction (Y direction) of the heating member 117 are uniform, and only the longitudinal direction (X direction) is the subject of consideration.

[0036] FIG. 12 is a diagram for explaining one-dimensional model analysis of the heating element 117. FIG. 12 shows the temperature distribution, with the horizontal axis representing the longitudinal direction of the heat generating element 120 and the vertical axis representing temperature. On the horizontal axis, the center position of the heat generating element 120 in the longitudinal direction is set to 0, and the heat generating element 120 and the flow path member 100 are arranged symmetrically with respect to this 0 position. That is, the heat generating element 120 is arranged from -x0 to x0, and the flow path member 100 that conducts its heat is arranged from -x1 to -x0 and from x0 to x1. The boundary temperatures are given at ±x1, which are the ends of the flow path member 100. Here, the boundary temperatures can be used as boundary conditions for partial differential equations in one-dimensional model analysis.

[0037] When the temperature distribution of the heat generating portion 120 and the flow path member 100 is calculated from the heat conduction equation under the above conditions, the temperature distribution 170 shown in Fig. 12 is obtained. The temperature distribution 170 has an upward convex shape with the temperature highest at position 0, and the temperature increases linearly in the range from -x1 to -x0 (flow path member 100), and decreases linearly in the range from x0 to x1 (flow path member 100). When the heat quantity of the heat generating part 120 is increased and the temperature distribution of the heat generating part 120 and the flow path member 100 is calculated using the heat conduction equation under the same conditions, the temperature distribution 171 shown in Fig. 12 is obtained. Compared to the temperature distribution 170, the temperature of the temperature distribution 171 is higher overall while the temperatures at the ±x1 boundaries are fixed.

[0038] The temperature range of the heat generating part 120 is defined as the difference between the maximum and minimum temperatures within the heater surface (surface 120a or surface 120b shown in FIG. 10). The temperature range of the heat generating part 120 in temperature distribution 170 is ΔT0. The temperature range of the heat generating part 120 in temperature distribution 171 is ΔT1. Since ΔT0<ΔT1, it can be seen that the temperature range of the heat generating part 120 becomes larger when the heat quantity of the heat generating part 120 is increased.

[0039] Fig. 13 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in Fig. 12 is applied to the heating element 117 shown in Fig. 9. In Fig. 13, the temperature distribution is shown at the top, with the horizontal axis representing the longitudinal direction (X direction) of the heating element 117 and the vertical axis representing the temperature. From the viewpoint of effectively heating the liquid 115 in the flow path 105, it is desirable that the temperature of the heating element 117 be uniform over the entire heater surface (here, the entire longitudinal range 129). Temperature distribution 126 is a comparative temperature distribution and corresponds to temperature distribution 170 shown in FIG. 12. In temperature distribution 126, the temperature range of the heating element 117 (the difference between the maximum temperature and the minimum temperature) is ΔT2. In order to effectively heat the liquid 115, it is desirable to make the temperature range ΔT2 as small as possible.

[0040] When a liquid with a high temperature suitable for ejection is used as the liquid 115, it is necessary to increase the amount of heat (power supply) of the heating element 117. Temperature distribution 127 is an example of a temperature distribution obtained when the amount of heat (power supply) of the heating element 117 is increased, and corresponds to distribution 171 shown in FIG. 12. In temperature distribution 127, the temperature range of the heating element 117 is ΔT3 (>ΔT2). As discussed in the one-dimensional model analysis shown in FIG. 12, increasing the amount of heat (power supply) of the heating element 117 increases the temperature of the entire heater surface and widens the temperature range ΔT3 of the heating element 117. This makes it difficult to effectively heat the liquid 115 and maintain the viscosity of the liquid 115 at an appropriate level.

[0041] On the other hand, in the liquid ejection head 10 of this embodiment, the temperature range of the heating member 113 can be made smaller than the temperature range of the heating member 117 of the comparative example. Fig. 14 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in Fig. 12 is applied to the heating element 113. In Fig. 14, the temperature distribution is shown with the horizontal axis representing the longitudinal direction (X direction) of the heating element 113 and the vertical axis representing the temperature. Temperature distributions 126 and 127 are the same as those shown in Fig. 13.

[0042] Temperature distribution 141 is an example of a temperature distribution obtained when the heat quantity (power supply) of heating element 113 is increased, similar to temperature distribution 127 shown in Fig. 13. In temperature distribution 141, the temperature range of heating element 113 is ΔT4 (<ΔT3). Even when the heat quantity of heating element 113 is increased, first conductive element 131 equalizes the heat, making it possible to make temperature range ΔT4 smaller than the temperature range ΔT3 of heating element 117 of the comparative example. As a result, it is possible to heat liquid 115 effectively and maintain the viscosity of liquid 115 at an appropriate level.

[0043] Furthermore, in addition to the above-mentioned effects, the liquid ejection head 10 of this embodiment also provides the following advantageous effects.

[0044] 13, there is a method of controlling the temperature of the heating element 117 based on the maximum temperature in the temperature distribution 127. In this method, the usable area of ​​the heater surface of the heating element 117 is limited (i.e., limited to the vicinity of the center of the heater surface) so that the temperature range is smaller than the temperature range ΔT3. Such a limitation of the usable area not only prevents effective heating of the liquid 115, but is also inefficient.

[0045] According to the liquid ejection head 10 of this embodiment, the temperature range ΔT4 of the heating member 113 is smaller than the temperature range ΔT3 of the heating member 117. Therefore, when the above-described temperature control method is performed, restrictions on the usable area of ​​the heater surface can be alleviated, and the liquid 115 can be heated effectively and efficiently.

[0046] 13, it is possible to control the temperature so that the average temperature of the entire temperature distribution 127 (for example, the average of the maximum and minimum temperatures) becomes a predetermined temperature. Specifically, the temperature distribution 127 is measured to calculate the average temperature, and if the calculated value is smaller than the predetermined temperature, the power supply to the heating element 117 is increased, and if the calculated value is larger than the predetermined temperature, the power supply to the heating element 117 is stopped. With this method, a locally high temperature portion (central portion) occurs on the heater surface, making it difficult to maintain the viscosity of the recording liquid 115 at an appropriate level or changing the characteristics of the recording liquid 115.

[0047] According to the liquid ejection head 10 of this embodiment, the temperature range ΔT4 is smaller than the temperature range ΔT3, and therefore when the temperature control method described above is performed, it is possible to prevent the heater surface from having a locally high temperature (central portion), thereby maintaining the viscosity of the recording liquid 115 at an appropriate level and preventing changes in the characteristics of the recording liquid 115.

[0048] 13, it is possible to reduce the temperature range ΔT3 by equalizing the heat using a heat sink, heat pipe, etc. However, adding new components such as a heat sink or heat pipe causes the liquid ejection head to become larger.

[0049] In contrast, in the liquid ejection head 10 of this embodiment, the heating member 113 has a multilayer structure in which a second layer 211 including a first conductive portion 131 is added to a first layer 210 including the heat generating portion 130. This multilayer structure makes it possible to prevent the head from becoming large. In addition, the heat generating portion 130, the first conductive portion 131, and the first coupling portion 132 form a current-carrying circuit. This makes it possible to stabilize the potential of the added second layer 211 (first conductive portion 131) in the multilayer structure.

[0050] (Second embodiment) FIG. 15 is a schematic diagram for explaining the configuration of a heating member used in a liquid ejection head according to a second embodiment of the present invention. Referring to FIG. 15, the heating member 114 is attached to the outer wall surface 200 of the flow path member 100 having the flow path 105. The heating member 114 has a heat generating portion 130, a first conductive portion 131, a first connecting portion 132, second conductive portions 145a to 145d, and second connecting portions 146a to 146d. The flow path member 100, the heat generating portion 130, the first conductive portion 131, and the first connecting portion 132 are the same as those shown in FIG. 3. Note that one second connecting portion 146a is provided for the second conductive portion 145a, but this is not limiting. A plurality of second connecting portions 146a may be provided for the second conductive portion 145a. The same applies to the number of second connecting portions 146b to 146d.

[0051] The second conductive portions 145a to 145d are provided along both edges in the short-side direction (Y direction) of the heat generating portion 130. The second conductive portions 145a and 145b are arranged near both ends of one edge, and the second conductive portions 145c and 145d are arranged near both ends of the other edge. The second coupling portion 146a electrically couples the second conductive portion 145a to the first conductive portion 131. The second coupling portion 146b electrically couples the second conductive portion 145b to the first conductive portion 131. The second coupling portion 146c electrically couples the second conductive portion 145c to the first conductive portion 131. The second coupling portion 146d electrically couples the second conductive portion 145d to the first conductive portion 131. The second conductive portions 145a to 145d and the second coupling portions 146a to 146d may be made of, for example, copper (Cu).

[0052] Fig. 16 is a cross-sectional view of the heating member 114 shown in Fig. 15. Fig. 16 schematically shows the cross-sectional structure of the heating member 114 in the short-side direction (Y direction). Referring to FIG. 16, the heating member 114 has a multi-layer structure and includes a first layer 210 including the heat generating portion 130 and second conductive portions 145a to 145d, and a second layer 211 including the first conductive portion 131.

[0053] Each of the second conductive portions 145a to 145d faces the first conductive portion 131. The first conductive portion 131 is disposed so as to entirely cover the heat generating portion 130 and the second conductive portions 145a to 145d. An insulating member 137 is provided between the first layer 210 and the second layer 211. In the first layer 210, the second conductive portions 145a to 145d are adjacent to the heat generating portion 130 and are electrically insulated from the heat generating portion 130, but are electrically coupled to the first conductive portion 131 via the second coupling portions 146a to 146d. The first conductive portion 131 and the second conductive portions 145a to 145d act to equalize the heat generated on the first surface 130a of the heat generating portion 130.

[0054] Next, the path of the current flowing through the heating member 114 will be described. FIG. 17 is a schematic diagram showing the path of current flowing through heating member 114. In FIG. 17, solid arrows indicate the path of current flow. The path of current through heating member 114 is the same as the path of current through heating member 114 shown in FIG. 7. Current supplied from power source 118 to terminal 140-2 passes through first conductive portion 131, first coupling portion 132, and heat generating portion 130 in this order, and returns to power source 118 via terminal 140-1. In this embodiment as well, heat generating portion 130, first conductive portion 131, and first coupling portion 132 form a current circuit (a closed circuit for power supply).

[0055] Next, the heat transfer path of the heating member 114 will be described. Fig. 18 is a schematic diagram showing the heat transfer path of the heating member 114. In Fig. 18, the hollow arrow a and the solid arrows b, c, and d indicate the transfer of heat.

[0056] The heat generated by the heat generating section 130 moves to both the flow path member 100 side and the first conductive member 131 side. On the first conductive member 131 side of the heat generating section 130, the heat moves to the first conductive member 131 via the insulating member 136 shown in FIG. 16 (white arrow a) and also moves to the first conductive member 131 via the first coupling section 132 (solid arrow b). Here, the temperature of the heat generating section 130 is highest in the center, and the white arrow a indicates the movement of heat in this center. In the first conductive member 131, the heat from the center of the surface 130a is diffused in the in-plane direction (solid arrow c). The heat movement indicated by the arrows a to c is the same as that shown in FIG. 8.

[0057] Furthermore, the heat diffused in the in-plane direction in the first conductive member 131 moves to the second conductive portions 145a-145d via the second coupling portions 146a-146d (solid line arrow d). Thus, in this embodiment, the second conductive portions 145a-145d, together with the first conductive member 131, act to equalize the heat generated on the first surface 130a of the heat generating portion 130.

[0058] Fig. 19 is a diagram for explaining the temperature distribution when the one-dimensional model analysis shown in Fig. 12 is applied to the heating element 114. In Fig. 19, the temperature distribution is shown with the horizontal axis representing the longitudinal direction (X direction) of the heating element 114 and the vertical axis representing the temperature. Temperature distributions 126, 127, and 141 are the same as those shown in Fig. 14.

[0059] Temperature distribution 151 is an example of a temperature distribution obtained when the amount of heat (power supply) of heating member 114 is increased, similar to temperature distribution 141 shown in FIG. 14. In temperature distribution 151, the temperature range of heating member 114 is ΔT5 (<ΔT4). By using second conductive portions 145a-145d in addition to first conductive member 131 to equalize the heat, temperature range ΔT5 can be made smaller than the temperature range ΔT4 of heating member 113 in the first embodiment. As a result, compared to the first embodiment, it is possible to heat liquid 115 more effectively and maintain the viscosity of liquid 115 more appropriately.

[0060] The liquid ejection head of this embodiment can also achieve the same effects as those described for the liquid ejection head of the first embodiment.

[0061] The configurations of the liquid ejection heads of the first and second embodiments described above are merely examples, and various modifications are possible as required. Below, variations that differ in detail will be described.

[0062] (Position of terminal to connect power supply) Of the pair of terminals 140-1 and 140-2 that connect the power supply 118, the terminal 140-1 is provided on the first conductive portion 131 of the second layer 211, and the terminal 140-2 is provided on the heat generating portion 130 of the first layer 210, but this is not limitative. The pair of terminals 140-1 and 140-2 may be provided on either the first layer 210 or the second layer 211.

[0063] For example, in the process of forming / connecting terminals 140-1 and 140-2, the metal portions of first conductive portion 131 and heat generating portion 130 are generally exposed, and the electric wires of power supply 118 are connected to the exposed portions by brazing, welding, or the like. However, if the process of exposing the metal portions is performed on both first layer 210 including heat generating portion 130 and second layer 211 including first conductive portion 131, the number of steps may increase and reliability may decrease. If terminals 140-1 and 140-2 are formed on either first layer 210 or second layer 211, the number of steps can be reduced and reliability can be improved.

[0064] A modified example in which a pair of terminals 140-1, 140-2 are provided on the first layer 210 will be described. In the liquid ejection head of the first or second embodiment, the heat generating section 130 is composed of a first divided heat generating section and a second divided heat generating section that are electrically insulated from each other. The first connecting section 132 is composed of a first divided connecting section and a second divided connecting section. The first divided connecting section electrically connects the first divided heat generating section and the first conductive section 131. The second divided connecting section electrically connects the second divided heat generating section and the first conductive section 131. One of the pair of terminals 140-1, 140-2 is provided on the first divided heat generating section, and the other is provided on the first divided heat generating section.

[0065] A modified example in which a pair of terminals 140-1, 140-2 are provided on the second layer 211 will be described. In the liquid ejection head of the first or second embodiment, the first conductive portion 131 is composed of a first divided conductive portion and a second divided conductive portion that are electrically insulated from each other. The first connecting portion 132 is composed of a first divided connecting portion and a second divided connecting portion. The first divided connecting portion electrically connects the first divided conductive portion and the heat generating portion 130. The second divided connecting portion electrically connects the second divided conductive portion and the heat generating portion 130. One of the pair of terminals 140-1, 140-2 is provided on the first divided conductive portion, and the other is provided on the second divided conductive portion.

[0066] A more specific configuration of a modified example in which the pair of terminals 140-1 and 140-2 are provided on the second layer 211 will be described below. FIG. 20 is a schematic diagram showing a first modified example of the liquid ejection head of the second embodiment. In this first modified example, in the heating member 114 shown in FIG. 15, the first conductive portion 131 is composed of a first divided conductive portion 131a, a second divided conductive portion 131b, and an insulating portion 131c. The first connecting portion 132 is composed of a first divided connecting portion 132a and a second divided connecting portion 132b. The first divided conductive portion 131a and the second divided conductive portion 131b are electrically insulated by the insulating portion 131c. A terminal 140-1 is provided on the first divided conductive portion 131a, and a terminal 140-2 is provided on the second divided conductive portion 131b.

[0067] The first divided coupling portion 132a electrically couples the first divided conductive portion 131a and the heat generating portion 130. The second divided coupling portion 132b electrically couples the second divided conductive portion 131b and the heat generating portion 130. The second coupling portion 146a electrically couples the second conductive portion 145a and the first divided conductive portion 131a. The second coupling portion 146b electrically couples the second conductive portion 145b and the first divided conductive portion 131a. The second coupling portion 146c electrically couples the second conductive portion 145c and the second divided conductive portion 131b. The second coupling portion 146d electrically couples the second conductive portion 145d and the second divided conductive portion 131b.

[0068] (Material of the second conductive part) In the liquid ejection head of the second embodiment, the first layer 210 includes the heat generating portion 130 and the second conductive portions 145a to 145d. By forming the heat generating portion 130 and the second conductive portions 145a to 145d from the same material, the head can be manufactured more easily and reliability is improved.

[0069] (Shape of the second conductive part) In the liquid ejection head of the second embodiment, the second conductive portions 145a to 145d are arranged at the four corners of the heat generating portion 130, but this is not limiting. The second conductive portions may be provided partially or entirely around the periphery of the heat generating portion 130.

[0070] Fig. 21 is a schematic diagram showing a second modified example of the liquid ejection head of the second embodiment. The second modified example shown in Fig. 20 uses second conductive portions 161a-161e and second connecting portions 147a-147l instead of the second conductive portions 145a-145d and second connecting portions 146a-146d in the heating member 114 shown in Fig. 20.

[0071] The second conductive portions 161a to 161e are provided to surround the peripheral edge of the heat generating portion 130. The second coupling portions 147a and 147b electrically couple the second conductive portion 161a to the conductive portion 131a. The second coupling portions 147c and 147d electrically couple the second conductive portion 161b to the conductive portion 131b. The second coupling portions 147e and 147f electrically couple the second conductive portion 161c to the conductive portion 131a. The second coupling portions 147g and 147h electrically couple the second conductive portion 161c to the conductive portion 131b. The second coupling portions 147i and 147j electrically couple the second conductive portion 161e to the conductive portion 131b. The second coupling portions 147k and 147l electrically couple the second conductive portion 161f and the conductive portion 131a.

[0072] According to the second modified example described above, the temperature range ΔT5 of the heating member 114 can be further reduced, so that the liquid 115 can be heated more effectively and the viscosity of the liquid 115 can be maintained more appropriately. In addition, if it is difficult to provide the second conductive portion around the entire circumference of the heat generating portion 130 due to reasons related to head manufacturing, the second conductive portion may be arranged only in the longitudinal direction or only in the lateral direction of the heat generating portion 130.

[0073] (Size of inner diameter (area) of first and second joints) Figure 22 is a cross-sectional view of the first coupling portion 132 and the second coupling portion 145a shown in Figure 16. Figure 22(a) shows an example of a structure in which the inner diameter of the first coupling portion 132 is larger than the inner diameter of the second coupling portion 145a. Figure 22(b) shows an example of a structure in which the inner diameter of the second coupling portion 145a is larger than the inner diameter of the first coupling portion 132. The first coupling portion 132 is the same as that shown in Figure 6.

[0074] As shown in FIG. 22, the second coupling portion 146a has a through hole 146-1 and a metal thin film 146-2 formed on the inner surface of the through hole 146-1. The through hole 146-1 penetrates the first layer 210, the insulating member 137, and the second layer 211. The second conductive portion 145a of the first layer 210 is electrically connected to the first conductive portion 131 of the second layer 211 via the metal thin film 146-2. The second coupling portion 146a can be formed by the same method as the first coupling portion 132. Although not shown in FIG. 12, the second coupling portions 146b to 146d also have the same structure as the second coupling portion 146a.

[0075] From the viewpoint of ease of manufacture, the inner diameter of the first coupling portion 132 may be the same as the inner diameter of the second coupling portion 146a. Furthermore, if it is desired to pass a large current in order to increase the amount of heat (electric power) of the heat generating portion 130, the inner diameter of the first coupling portion 132 may be made larger than the inner diameter of the second coupling portion 146a, as shown in Fig. 22(a). Increasing the inner diameter of the first coupling portion 132 increases the area (surface area) on which the thin metal film 146-2 is formed, and as a result, the electrical resistance of the first coupling portion 132 is reduced, making it easier for a current to flow. On the other hand, if the effect of equalizing heat is prioritized over the ease of current flow, the inner diameter of the second coupling portion 146a may be made larger than the inner diameter of the first coupling portion 132, as shown in FIG. 22(b).

[0076] Both the first coupling portions 132 and the second coupling portions 146a are configured to penetrate the first layer 210, the insulating member 137, and the second layer 211. Therefore, from the viewpoint of the mechanical strength of the heating member 114, it is preferable that the number of first coupling portions 132 and second coupling portions 146a be as small as possible. Moreover, in order to facilitate pattern formation of the heat generating part 130 and formation of terminals for power supply connection, it is preferable that the first coupling part 132 be provided at the end of the heat generating part 130.

[0077] (Relationship between the size of the heat generating part and the size of the first conductive part) 23A and 23B are schematic diagrams illustrating the size relationship between the heat generating portion 130 and the first conductive portion 131. Fig. 23A shows an example of the size relationship, and Fig. 23B shows another example of the size relationship.

[0078] 23(a), in the heating element 113 (114), when the heat generating portion 130 and the first conductive portion 131 are projected in the thickness direction of the heating element 113 (114), the first conductive portion 131 encompasses the heat generating portion 130. According to this relationship, the temperature range ΔT4 (ΔT5) can be reduced efficiently and effectively.

[0079] 23(b), in the heating element 113 (114), when the heat generating portion 130 and the first conductive portion 131 are projected in the thickness direction of the heating element 113 (114), the projected area of ​​the first conductive portion 131 is larger than the projected area of ​​the heat generating portion 130. This relationship also makes it possible to efficiently and effectively reduce the temperature range ΔT4 (ΔT5).

[0080] (Arrangement (order) of each layer of heating element relative to flow path element) In the heating members 113 and 114, the first conductive part 131 is arranged on the side of the heat generating part 130 opposite to the flow path member 100 side, but is not limited to this. The first conductive part 131 may also be arranged on the flow path member 100 side of the heat generating part 130.

[0081] Fig. 24 is a schematic diagram showing a first modified example of the liquid ejection head of the first embodiment. The first modified example shown in Fig. 24 is basically the same as the configuration of the heating member 113 shown in Fig. 3, except that the first conductive part 131 is arranged on the flow path member 100 side of the heat generating part 130. Terminal 141-1 is provided on the heat generating part 130, and terminal 141-2 is provided on the first conductive part 131.

[0082] FIG. 25 is a cross-sectional view of the heating member 113 shown in FIG. 24. FIG. 25 shows the cross-sectional structure shown in FIG. 4, with the first layer 210 including the heat generating portion 130 and the second layer 211 including the first conductive portion 131 interchanged. The first conductive portion 131 is fixed to the outer wall surface 200 of the flow path member 100 via an adhesive member 135 and an insulating member 136. The first conductive portion 131 faces the second surface 130b of the heat generating portion 130. Heat generated on the second surface 130b of the heat generating portion 130 is conducted to the flow path member 100 via the first conductive portion 131. The first conductive portion 131 acts to equalize the heat generated on the second surface 130b of the heat generating portion 130.

[0083] Fig. 26 is a schematic diagram showing the heat transfer path of the heating member 113 shown in Fig. 24. In Fig. 26, the outline arrow a and the solid arrows b and c indicate the transfer of heat. Heat generated by the heat generating unit 130 travels from both the first surface 130a and the second surface 130b. Heat from the second surface 130b travels to the first conductive portion 131 via the insulating member 137 (white arrow a) and also travels to the first conductive member 131 via the first coupling portion 132 (solid arrow b). Here, the temperature of the second surface 130b is highest in the center, and the white arrow a indicates the transfer of heat in this center. In the first conductive member 131, the heat from the center of the second surface 130b is diffused in the in-plane direction (solid arrow c). In this way, the first conductive member 131 acts to equalize the heat generated on the second surface 130b of the heat generating unit 130.

[0084] The heat equalized by the first conductive member 131 is transferred to the flow path member 100 via the insulating member 136 and the adhesive member 135. This type of heat conduction also makes it possible to heat the liquid 115 effectively.

[0085] The disclosure of this embodiment includes the following configuration. (Configuration 1) a flow path member having a flow path through which a liquid flows; a heating member attached to an outer wall surface of the flow path member to heat the liquid in the flow path, The heating element is a first layer including a heat generating portion that generates heat when energized; a second layer including a first conductive portion facing one surface of the heat generating portion; a first coupling portion that electrically couples the heat generating portion and the first conductive portion; (Configuration 2) the first layer includes a second conductive portion adjacent to the heat generating portion and electrically insulated from the heat generating portion; 2. The liquid ejection head according to configuration 1, further comprising a second coupling portion that electrically couples the first conductive portion and the second conductive portion. (Configuration 3) 3. The liquid ejection head according to configuration 2, wherein the second conductive portion is provided so as to surround the peripheral edge of the heat generating portion. (Configuration 4) 3. The liquid ejection head according to configuration 2, wherein the second conductive portion is provided along both edges of the heat generating portion that face each other in the longitudinal direction. (Configuration 5) 3. The liquid ejection head according to configuration 2, wherein the second conductive portion is provided along both edge portions that face each other in the short direction of the heat generating portion. (Configuration 6) 6. The liquid ejection head according to any one of configurations 2 to 5, wherein the second conductive portion is made of the same material as the heat generating portion. (Configuration 7) A liquid ejection head described in any one of configurations 2 to 6, wherein the first connecting portion and the second connecting portion each have a structure in which a thin metal film is formed on the inner surface of a through hole that penetrates the first and second layers, and the inner diameter of the through hole of the first connecting portion is larger than the inner diameter of the through hole of the second connecting portion. (Configuration 8) A liquid ejection head described in any one of configurations 2 to 6, wherein the first connecting portion and the second connecting portion each have a structure in which a thin metal film is formed on the inner surface of a through hole that penetrates the first and second layers, and the inner diameter of the through hole of the second connecting portion is larger than the inner diameter of the through hole of the first connecting portion. (Configuration 9) 9. The liquid ejection head according to any one of configurations 1 to 8, wherein the first connecting portion is formed at an end of the heat generating portion. (Configuration 10) 10. The liquid ejection head according to any one of configurations 1 to 9, wherein one of a pair of terminals for energizing is provided on the heat generating portion, and the other of the pair of terminals is provided on the first conductive portion. (Configuration 11) 10. The liquid ejection head according to any one of configurations 1 to 9, wherein a pair of terminals for energizing the liquid are provided on the first layer. (Configuration 12) A liquid ejection head as described in configuration 11, wherein the heat generating portion comprises a first divided heat generating portion and a second divided heat generating portion that are electrically insulated from each other, the first connecting portion comprises a first divided connecting portion and a second divided connecting portion, the first divided connecting portion electrically connects the first divided heat generating portion and the first conductive portion, the second divided connecting portion electrically connects the second divided heat generating portion and the first conductive portion, one of the pair of terminals is provided on the first divided heat generating portion, and the other of the pair of terminals is provided on the first divided heat generating portion. (Configuration 13) 10. The liquid ejection head according to any one of configurations 1 to 9, wherein a pair of terminals for energizing the liquid are provided on the second layer. (Configuration 14) A liquid ejection head as described in configuration 13, wherein the first conductive portion comprises a first divided conductive portion and a second divided conductive portion that are electrically insulated from each other, the first connecting portion comprises a first divided connecting portion and a second divided connecting portion, the first divided connecting portion electrically connects the first divided conductive portion to the heat generating portion, the second divided connecting portion electrically connects the second divided conductive portion to the heat generating portion, one of the pair of terminals is provided on the first divided conductive portion, and the other of the pair of terminals is provided on the second divided conductive portion. (Configuration 15) A liquid ejection head described in any one of configurations 1 to 14, wherein when the heat generating portion and the first conductive portion are projected in the thickness direction of the heating member, the first conductive portion covers the heat generating portion. (Configuration 16) A liquid ejection head described in any one of configurations 1 to 14, wherein when the heat generating portion and the first conductive portion are each projected in the thickness direction of the heating member, the projected area of ​​the first conductive portion is larger than the projected area of ​​the heat generating portion. (Configuration 17) A liquid ejection head described in any one of configurations 1 to 16, wherein the heating member is attached to the outer wall surface of the flow path member so that the first layer is positioned between the flow path member and the second layer. (Configuration 18) A liquid ejection head described in any one of configurations 1 to 16, wherein the heating member is attached to the outer wall surface of the flow path member so that the second layer is positioned between the flow path member and the first layer. [Explanation of symbols]

[0086] 100 Flow path member 113 Heating element 130 Heat generating part 131 first conductive part 132 First Joint 210 First Layer 211 Second Layer

Claims

1. a flow path member having a flow path through which a liquid flows; a heating member attached to an outer wall surface of the flow path member to heat the liquid in the flow path, The heating element is a first layer including a heat generating portion that generates heat when energized; a second layer including a first conductive portion facing one surface of the heat generating portion; a first coupling portion that electrically couples the heat generating portion and the first conductive portion;

2. the first layer includes a second conductive portion adjacent to the heat generating portion and electrically insulated from the heat generating portion; The liquid ejection head according to claim 1 , further comprising a second coupling portion that electrically couples the first conductive portion and the second conductive portion.

3. The liquid ejection head according to claim 2 , wherein the second conductive portion is provided so as to surround the peripheral edge of the heat generating portion.

4. 3. The liquid ejection head according to claim 2, wherein the second conductive portion is provided along both edges of the heat generating portion that face each other in the longitudinal direction.

5. The liquid ejection head according to claim 2 , wherein the second conductive portion is provided along both edge portions of the heat generating portion that face each other in the lateral direction of the heat generating portion.

6. The liquid ejection head according to claim 2 , wherein the second conductive portion is made of the same material as the heat generating portion.

7. A liquid ejection head as described in claim 2, wherein the first connecting portion and the second connecting portion each have a structure in which a thin metal film is formed on the inner surface of a through hole penetrating the first and second layers, and the inner diameter of the through hole of the first connecting portion is larger than the inner diameter of the through hole of the second connecting portion.

8. A liquid ejection head as described in claim 2, wherein the first connecting portion and the second connecting portion each have a structure in which a thin metal film is formed on the inner surface of a through hole penetrating the first and second layers, and the inner diameter of the through hole of the second connecting portion is larger than the inner diameter of the through hole of the first connecting portion.

9. The liquid ejection head according to claim 1 , wherein the first connecting portion is formed at an end of the heat generating portion.

10. 2. The liquid ejection head according to claim 1, wherein one of the pair of terminals for energizing is provided on the heat generating portion, and the other of the pair of terminals is provided on the first conductive portion.

11. 2. The liquid ejection head according to claim 1, wherein a pair of terminals for energizing the liquid are provided on the first layer.

12. 12. A liquid ejection head as described in claim 11, wherein the heat generating portion comprises a first divided heat generating portion and a second divided heat generating portion that are electrically insulated from each other, the first connecting portion comprises a first divided connecting portion and a second divided connecting portion, the first divided connecting portion electrically connects the first divided heat generating portion and the first conductive portion, the second divided connecting portion electrically connects the second divided heat generating portion and the first conductive portion, one of the pair of terminals is provided on the first divided heat generating portion, and the other of the pair of terminals is provided on the first divided heat generating portion.

13. 2. The liquid ejection head according to claim 1, wherein a pair of terminals for energizing the liquid are provided on the second layer.

14. A liquid ejection head as described in claim 13, wherein the first conductive portion comprises a first divided conductive portion and a second divided conductive portion that are electrically insulated from each other, the first connecting portion comprises a first divided connecting portion and a second divided connecting portion, the first divided connecting portion electrically connects the first divided conductive portion to the heat generating portion, the second divided connecting portion electrically connects the second divided conductive portion to the heat generating portion, one of the pair of terminals is provided on the first divided conductive portion, and the other of the pair of terminals is provided on the second divided conductive portion.

15. The liquid ejection head according to claim 1 , wherein when the heat generating portion and the first conductive portion are projected in the thickness direction of the heating member, the first conductive portion covers the heat generating portion.

16. The liquid ejection head according to claim 1 , wherein when the heat generating portion and the first conductive portion are projected in the thickness direction of the heating member, the projected area of ​​the first conductive portion is larger than the projected area of ​​the heat generating portion.

17. The liquid ejection head according to claim 1 , wherein the heating member is attached to the outer wall surface of the flow path member such that the first layer is located between the flow path member and the second layer.

18. The liquid ejection head according to claim 1 , wherein the heating member is attached to the outer wall surface of the flow path member such that the second layer is located between the flow path member and the first layer.

Images