Liquid discharge head and method for manufacturing same

Abstract

To provide a liquid discharge head suppressed in deformation even when a pressure chamber is formed by using a resin.SOLUTION: The liquid discharge head comprises: a nozzle plate provided with a nozzle for discharging a liquid; and a substrate having a piezoelectric element configured to generate pressure for discharging the liquid through the nozzle. A wall member including a resin is provided between the nozzle plate and the substrate. A space surrounded by the wall member, the nozzle plate, and the substrate communicates with the nozzle. A structure configured to connect at least two side surfaces among the four side surfaces of the wall member forming the space is provided.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a manufacturing method thereof. [Background technology]

[0002] In order to achieve higher definition and quality printing in an inkjet printer as a liquid ejection device, it is necessary to improve the processing accuracy of the liquid ejection head and make the liquid ejection head more precise. Patent Document 1 describes a piezoelectric liquid ejection head that uses a photosensitive resin in the pressure chamber, making it possible to highly integrate nozzles at low cost. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4300565 Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid ejection head described in Patent Document 1, it is shown that the nozzles can be highly integrated by increasing the processing accuracy by using a photosensitive resin to form the pressure chambers. However, when the nozzle integration is increased, the walls between adjacent pressure chambers become thinner and more susceptible to deformation, which may result in a decrease in the liquid ejection frequency.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS In order to solve the above problems, an object of the present invention is to provide a liquid ejection head in which deformation is suppressed even when a pressure chamber is formed using resin, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a liquid ejection head comprising a nozzle plate provided with a nozzle for ejecting liquid, and a substrate having a piezoelectric element configured to generate pressure for ejecting liquid from the nozzle, wherein a wall member containing a resin is provided between the nozzle plate and the substrate, and a space surrounded by the wall member, the nozzle plate and the substrate is connected to the nozzle, and a structure configured to connect at least two of four sides of the wall member to form the space is provided.

[0007] The present invention also provides a method for manufacturing a liquid ejection head, comprising: a nozzle plate provided with a nozzle for ejecting liquid; and a substrate having a piezoelectric element configured to generate pressure for ejecting liquid from the nozzle; a wall member containing resin is provided between the nozzle plate and the substrate; a space surrounded by the wall member, the nozzle plate, and the substrate communicates with the nozzle to form the space; and a structure configured to connect at least two of four side surfaces of the wall member is provided, the method comprising the steps of forming the piezoelectric element on the substrate, forming the wall member on the substrate using a photosensitive resin, and bonding the nozzle plate to the wall member, wherein the step of forming the wall member comprises the steps of molding a first photosensitive resin and exposing it to light, molding a second photosensitive resin on the first photosensitive resin and exposing it to light, and developing the first photosensitive resin and the second photosensitive resin all at once. Effect of the Invention

[0008] As a result of intensive research, the inventors of the present application have discovered that when forming the walls that constitute the pressure chambers using photosensitive resin, by also creating structures that support at least two side walls of the pressure chambers, a decrease in the liquid ejection frequency can be suppressed. According to the present invention, a liquid ejection head in which deformation is suppressed even when the pressure chambers are formed using resin, and a manufacturing method thereof are provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Diagram 2] FIG. 1 is a diagram illustrating an example of a liquid ejection head of a comparative example. [Diagram 3] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Figure 4] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Diagram 5] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Figure 6] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Figure 7] 1 is a diagram illustrating an example of a liquid ejection head of the present invention. [Figure 8] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. [Figure 9] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. [Figure 10] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. [Figure 11] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. [Figure 12] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. [Figure 13] 5A to 5C are diagrams illustrating an example of a method for manufacturing a liquid ejection head according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 is a top view showing an example of a liquid ejection head of the present invention, as viewed from the nozzle 11 side. The dashed lines in the figure indicate part of the internal structure that cannot be seen from the nozzle 11 side. A plurality of nozzles 11 are lined up in a row, and roughly rectangular parallelepiped pressure chambers 10 corresponding to each nozzle 11 are arranged with their long sides adjacent to each other in the short direction of the pressure chambers. The shape of the pressure chambers does not have to be limited to a roughly rectangular parallelepiped shape.

[0011] First, the problem of the present invention will be described with reference to FIG. 2 and a liquid ejection head of a comparative example. FIG. 2(A) is a cross-sectional view along the longitudinal direction of the pressure chamber. The substrate 1 has a piezoelectric element 2, a vibration plate 3, and a liquid supply port 4. Here, the piezoelectric element has a substantially rectangular shape extending in the longitudinal direction of the pressure chamber 10, which is a substantially rectangular parallelepiped. A pressure chamber wall member 5 is connected to the surface of the substrate 1 on the side having the vibration plate 3, and a nozzle plate 6 provided with a nozzle 11 is connected to the surface of the pressure chamber wall member opposite the substrate 1 side. The pressure chamber 10 is a space surrounded by the nozzle plate 6, the substrate 1, and the pressure chamber wall member 5, and communicates with the nozzle 11. The liquid supplied from the liquid supply port 4 to the pressure chamber 10 and the nozzle 11 drives the piezoelectric element 2, and the vibration plate 3 bends toward the inside of the pressure chamber 10, and is ejected from the nozzle. The pressure chamber wall member 5 is formed of a resin such as a photosensitive material, which makes it possible to realize high integration of nozzles at low cost. Furthermore, it is easier to improve the processing accuracy compared to when the pressure chamber wall member 5 is made of an inorganic material.

[0012] Fig. 2(B) is a cross-sectional view taken along CC' in Fig. 2(A), and Fig. 2(D) is a perspective view of the pressure chamber wall member 5 as viewed from the bonding surface with the nozzle plate 6. A plurality of pressure chambers 10 are arranged adjacent to each other in the short direction of the pressure chambers 10, sandwiching a pressure chamber wall 50 therebetween. If a plurality of nozzles 11 and pressure chambers 10 are formed at high density and the pressure chamber wall 50 is thin, the pressure chamber wall 50 becomes easily deformed as shown in Fig. 2(B). This may affect the ejection of liquid.

[0013] FIG. 2(C) is a diagram showing an example of a manufacturing process of a liquid ejection head of a comparative example, showing a state in which a pressure chamber wall member 5 is connected to a substrate 1. When processing a pressure chamber wall member 5 having a pressure chamber 10 using a resin, the pressure chamber wall 50 of the pressure chamber wall member 5 may be deformed. The deformation of the pressure chamber wall 50 may occur in a developing process, a drying process, a heat treatment process when the resin is a photosensitive resin, and in a subsequent surface treatment process, a film formation process, a process of forming a nozzle plate 6, etc. This may result in insufficient processing accuracy of the pressure chamber in the liquid ejection head, which may affect the ejection of liquid. The deformation of the pressure chamber wall 50 becomes more noticeable as the wall width becomes narrower and the longitudinal length of the pressure chamber 10 becomes longer. Another factor that makes the pressure chamber wall 50 more likely to deform is that the pressure chamber wall member 5 is made of a resin with low rigidity.

[0014] An example of a liquid ejection head of the present invention is shown in Fig. 3. As with the liquid ejection head of the comparative example described above, the pressure chamber wall member 5 is made of a resin such as a photosensitive material. From the viewpoint of improving processing accuracy, the resin used is preferably a photosensitive resin, and furthermore, from the viewpoint of heat resistance, it is more preferable that the resin used is a photosensitive epoxy resin.

[0015] FIG. 3(A) is a cross-sectional view taken along line A-A' in FIG. 1, and is a cross-sectional view taken along the longitudinal direction of the pressure chamber 10. FIG. 3(B) is a cross-sectional view taken along line B-B' in FIG. 1. FIG. 3(D) is a perspective view of the pressure chamber wall member 5 as viewed from the joining surface with the nozzle plate 6. FIG. 3(E) is a cross-sectional view taken along line D-D' in FIG. 3(A), and shows only the pressure chamber wall member 5. The liquid ejection head of the present invention is provided with a structure 7 configured to connect at least two of the four side surfaces (pressure chamber walls 50) that form the pressure chamber 10 (space). FIG. 3(B) shows how the pressure chamber wall 50 is supported by the structure 7. The structure 7 has the effect of suppressing deformation of the pressure chamber wall member 5. This makes it easier to make the pressure chamber wall 50 thinner, and has the effect of enabling further integration of the nozzles 11.

[0016] 3, the structure 7 is formed integrally with the pressure chamber wall member 5. By integrally forming the structure 7 from the same resin (same material) as the pressure chamber wall member 5, high processing accuracy can be obtained and the manufacturing process can be simplified. Note that the structure 7 may be a different material from the pressure chamber wall member 5.

[0017] Fig. 3(C) is a diagram showing an example of a process for manufacturing a liquid ejection head according to the present invention, and shows a state in which a pressure chamber wall member 5 is connected to a substrate 1. Compared to the comparative example shown in Fig. 2(C), deformation of the pressure chamber wall member 5 (pressure chamber wall 50) is suppressed by the structure 7 connecting the pressure chamber walls 50.

[0018] In addition, as shown in FIG. 3, it is preferable that the structure 7 continuously connects the pressure chamber walls 50 between the spaces in the short-side direction of the pressure chamber 10. In this case, the deformation suppression effect relative to the size of the structure 7 is high, which is preferable for increasing the density of the nozzle 11. As shown in FIG. 3(A) and (B), the height of the pressure chamber 10 is T, and the thickness of the pressure chamber walls 50 between adjacent pressure chambers 10 in the short-side direction (thickness of the pressure chamber wall member 5) is L. As a result of the inventor forming the pressure chamber wall member from an epoxy resin-based negative photosensitive material, when the aspect ratio is T / L>6, the deformation of the pressure chamber wall 50 after photosensitive resin development was confirmed to be significant. Therefore, the larger the ratio of T, the more likely it is that the processing accuracy will decrease, and the occurrence rate of the pressure chamber wall 5 being greatly deformed during the manufacture of the head will increase. Since the structure 7 of the present invention suppresses the deformation of the wall, the higher the ratio of T in the aspect ratio L:T, the higher the effect of suppressing the decrease in processing accuracy or the effect of suppressing the deformation of the pressure chamber according to the present invention, which is preferable. The ratio of T to L preferably satisfies the relationship T / L>1, and is preferably T / L>2, which is higher than the commonly used dimensional ratio L:T=1:2. Furthermore, it is more preferable that T / L>4, which allows doubling the nozzle integration density with a general structure, and even more preferable that T / L>6, in which deformation after development becomes an issue.

[0019] 4(A) to 4(E) are diagrams showing various examples of the arrangement of the structure 7 in the liquid ejection head of the present invention, and in any configuration, the structure 7 can provide the effect of suppressing deformation of the pressure chamber wall 50. Furthermore, as shown in Fig. 4, the nozzle 11 may have a multi-stage structure.

[0020] As shown in FIG. 4A, the surface of the pressure chamber 10 that contacts the vibration plate 3 is the first surface 100, and the surface of the pressure chamber 10 that contacts the nozzle plate 6 is the second surface 200. The first surface 100 is the surface of the pressure chamber on the piezoelectric element side, and the second surface 200 is the surface of the pressure chamber on the nozzle plate side. In FIG. 4A, the structure 7 is disposed at a position that contacts the first surface 100. When the structure 7 is disposed at a position that faces the piezoelectric element 2 through the vibration plate 3 as in FIG. 4A, the deformation suppression effect of the pressure chamber wall 50 can be obtained, but the operation of the vibration plate 3 when the piezoelectric element 2 is driven may be affected. Therefore, when the structure 7 is disposed on the first surface 100, it is preferable to dispose it at a position that does not face the piezoelectric element through the vibration plate 3.

[0021] 4(B), the structure 7 is disposed at a position away from both the first surface 100 and the second surface 200. In this case, the effect of suppressing deformation of the pressure chamber wall 50 can be obtained while the influence on the operation of the vibration plate 3 when the piezoelectric element 2 is driven is small, so that this is preferable to a configuration in which the structure 7 is disposed on the first surface 100.

[0022] In FIG. 4(C), the structure 7 is disposed on the first surface 100, and is disposed on both ends of the piezoelectric element 2 in the longitudinal direction of the pressure chamber 10. Since the structure 7 is located at a position that does not face the piezoelectric element 2 across the vibration plate 3, the deformation of the pressure chamber wall 50 is suppressed without significantly affecting the operation of the vibration plate 3 when the piezoelectric element 2 is driven. Furthermore, since the structure 7 is located at both ends of the piezoelectric element 2, the effect of concentrating the pressure of the liquid on the nozzle 11 is obtained, which is preferable. In FIG. 4(D), the structure 7 is disposed at a position away from both the first surface 100 and the second surface 200, and at a position facing both ends of the piezoelectric element 2. Also, in FIG. 4(E), the structure 7 is disposed on the second surface 200, and at a position facing both ends of the piezoelectric element 2. 4(C)-(D), when viewed in plan from a direction perpendicular to the substrate, the structures 7 are disposed at both longitudinal ends of the piezoelectric element 2, thereby obtaining the effect of suppressing deformation of the pressure chamber wall 50 while minimizing the effect on the operation of the piezoelectric element 2 and the diaphragm 3. Furthermore, this is more preferable because it has the effect of concentrating the pressure of the liquid on the nozzle 11.

[0023] Fig. 5 is a diagram showing another example of the configuration of the liquid ejection head of the present invention. As shown in Fig. 5(A) to (C), the structure 7 may reinforce the pressure chamber wall 50 in the longitudinal direction to suppress deformation. Fig. 5(A) is a cross-sectional view at a position corresponding to D-D' in Fig. 3, Fig. 5(B) is a cross-sectional view at A-A' in Fig. 5(A), and Fig. 5(C) is a cross-sectional view at B-B' in Fig. 5(A).

[0024] As shown in Figs. 5(D) to (F), the structure 7 reinforces the pressure chamber wall 50 in the longitudinal direction and further connects the pressure chamber wall 50 continuously in the lateral direction, thereby enhancing the effect of suppressing deformation of the pressure chamber wall 50. Fig. 5(D) is a cross-sectional view at a position corresponding to D-D' in Fig. 3, Fig. 5(E) is a cross-sectional view at C-C' in Fig. 5(D), and Fig. 5(F) is a cross-sectional view at D-D' in Fig. 5(D). Here, when viewed in a plan view from a direction perpendicular to the substrate 1, the area of ​​the vibration plate 3 corresponding to each pressure chamber 10 and the piezoelectric element 2 is defined as an effective vibration area, the length of the effective vibration area in the longitudinal direction is R, and the length of the part of the longitudinal length that does not overlap with the structure 7 is S. Considering the suppression of deformation of the pressure chamber wall 50 and the efficiency of transmitting the pressure of liquid ejection to the nozzle, the ratio of S to R is preferably 30% to 90%, more preferably 50% to 70%.

[0025] As shown in Figs. 5(G) to (I), the pressure chamber 10 may have a length Q of which the structure 7 is not included in the length P in the longitudinal direction. Fig. 5(G) is a cross-sectional view at a position corresponding to D-D' in Fig. 3, Fig. 5(H) is a cross-sectional view at E-E' in Fig. 5(G), and Fig. 5(I) is a cross-sectional view at F-F' in Fig. 5(G). Since a part of the pressure applied to the liquid escapes from the nozzle 11 to the outside, the length Q of which the structure 7 is not included is disposed adjacent to the nozzle 11, thereby enhancing the effect of suppressing deformation of the pressure chamber wall 50. Furthermore, the design constraint due to the structure 7 is reduced, and the effect of increasing the design freedom of the nozzle 11 is obtained. The smaller the ratio of Q to P, the higher the effect of suppressing deformation of the wall, and is preferably 90% or less, more preferably 70% or less, and even more preferably 50% or less. In addition, it is preferable to have a structure in which the ratio of the overlapping portion of the structure 7 and the pressure chamber 10 decreases from the liquid supply port 4 toward the nozzle side when viewed in a plan view from a direction perpendicular to the substrate 1. In this case, the effect of concentrating the pressure of the liquid ejection pressure applied to the liquid from the piezoelectric element to the nozzle can be increased. The greater the ratio of the length of the structure to the length of the pressure chamber in the longitudinal direction (the longitudinal direction of the space), the greater the effect, and it is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0026] Figure 6 is a diagram showing another example of a liquid ejection head according to the present invention. As shown in Figure 6(A), even when the height of the nozzle 11 in the direction perpendicular to the substrate 1 is large, the effect of the structure 7 can be obtained.

[0027] 6(B) shows a case where the structure 7 and the pressure chamber wall member 5 are integrated. Even in this case, the effect of providing the structure 7 can be obtained. The structure is a member that reinforces the pressure chamber wall 50. When the structure 7 and the pressure chamber wall 50 are integrated, the portion of the pressure chamber wall member 5 that faces the diaphragm 3 is regarded as the structure 7.

[0028] 6(C) shows structure 7 and structure 70, which also functions as a damper having a vibration suppressing effect on the liquid to prevent crosstalk. Giving structure 7 a function other than supporting the pressure chamber wall reduces the number of components and facilitates manufacturing.

[0029] 6(D) shows a configuration having a structure 7, in which the nozzle plate 6 is made up of multiple members, and the liquid supply port 4 is disposed in the pressure chamber wall member 5. Even in this configuration, the structure 7 has a role of supporting the pressure chamber wall, and has the effect of concentrating the pressure applied to the liquid from the piezoelectric element to the nozzle.

[0030] As shown in Fig. 7, the effects of the present invention can be obtained even in a liquid ejection head configured to circulate liquid inside. The substrate 1 has a liquid supply port 4a for supplying liquid to the pressure chamber 10, and a liquid outlet port 4b for causing the liquid to flow out from the pressure chamber 10. In all of the liquid ejection heads of the present invention shown in Fig. 7, the structures 7 continuously connect the pressure chamber walls 50 in the short side direction.

[0031] In Fig. 7(A), the structure 7 is disposed on both ends of the piezoelectric element 2 on the first surface 100. In Fig. 7(B), the structure 7 is disposed on both ends of the piezoelectric element 2 on the second surface 200. In either structure, the structure 7 exerts the effect of suppressing deformation of the pressure chamber wall 50, but the efficiency of liquid circulation inside the nozzle 11 is higher in Fig. 7(A) and is therefore preferable.

[0032] In FIG. 7(C), the structures 7 are disposed on both ends of the piezoelectric element 2 in the direction of circulation of the liquid, on the second surface 200 on the liquid supply port 4a side of the nozzle, and on the first surface 100 on the liquid outlet 4b side of the nozzle. This configuration provides the effect of promoting liquid circulation into the nozzle 11. The arrangement of the nozzle 11 can be adjusted between the front and rear structures. Also, in addition to the configuration of FIG. 7(C), FIG. 7(D) further includes a structure 7 that contacts the first surface 100 on the liquid supply port 4a side, in addition to the structure 7 that contacts the second surface on the liquid supply port 4a side of the nozzle 11. That is, in the direction of circulation of the liquid, a structure that contacts the first surface and a structure that contacts the second surface are provided on the liquid supply port side of the nozzle. Also, by adjusting the arrangement of the structures 7, the effect of efficiently adjusting the liquid resistance on the liquid supply port 4a side can be obtained. 7(E) shows a configuration in which a part of the nozzle 11 protrudes toward the liquid outlet 4b side from the structure 7, which has the effect of improving the efficiency of liquid circulation inside the nozzle 11. FIG. 7(F) shows a configuration in which a part of the nozzle 11 protrudes toward the liquid outlet 4b side from the structure 7, which has the effect of improving the efficiency of liquid circulation inside the nozzle. In addition, on the liquid supply port 4a side, the structure 7 is provided in contact with the first surface 100 at the rear, and the liquid supply port 4a further has the structure 7 in contact with the second surface 200, which has the effect of making it possible to adjust the liquid resistance at a location away from the nozzle 11.

[0033] An example of a method for manufacturing a liquid ejection head according to the present invention will be described with reference to Fig. 8. Each of the following steps can be performed using a known technique.

[0034] As shown in Fig. 8(A), a substrate 1 having a piezoelectric element 2 is prepared. In Fig. 8(A), the substrate 1 further has a vibration plate 3, a liquid supply port 4a, and a liquid outlet port 4b.

[0035] Next, as shown in FIG. 8(B), a mold material 8 is formed on the substrate 1. A photosensitive material mainly composed of novolac resin, acrylic resin, or the like can be used for the mold material 8. Alternatively, cyclized rubber or the like can be used. In order to form the mold material 8 from a photosensitive material, by changing the exposure conditions for each location, it is possible to form a portion that penetrates to the first surface of the substrate during development and a portion that does not penetrate. The portion that does not penetrate becomes the portion that corresponds to the structure 7 when the pressure chamber wall member 5 is formed.

[0036] Next, as shown in FIG. 8(C), the pressure chamber wall member 5 is formed on the mold material 8 using a photosensitive resin. The pressure chamber wall member 5 can be formed by a method such as spin coating, slit coating, spray coating, nanoimprinting, dipping, or a method using a dry film. Next, exposure and development using a mask are performed to form the nozzle 11. Here, when forming the pressure chamber wall member 5 on the mold material 8, the unevenness of the mold material 8 may affect the flatness of the pressure chamber wall member 5. In that case, a flattening process such as polishing may be added after the pressure chamber wall member is formed.

[0037] Next, as shown in Fig. 8(D), the mold material 8 is removed. The mold material 8 can be removed by dry processing or wet processing, and wet processing is preferable because it is easy to obtain a selectivity with respect to the pressure chamber wall member 5. By removing the mold material 8, the pressure chamber wall member 5 including the structures 7 is formed. In the liquid ejection head shown in Fig. 8, the nozzle plate 6 and the pressure chamber wall member 5 are configured to be integrated together.

[0038] Furthermore, as shown in FIG. 8(E), a functional film 9 may be formed on the pressure chamber wall member 5 and the structure 7. The functional film 9 may be formed on a location other than the pressure chamber wall member 5 or the structure 7. From the viewpoint of liquid ejection, the functional film 9 is preferably a film that enhances the strength of the pressure chamber wall member 5. The functional film 9 may be used as a protective film that prevents damage during the manufacturing process or enhances resistance to the liquid that the liquid ejection head comes into contact with, or as a film that adjusts affinity with the liquid, and may be a laminated film of films having these functions. In order to enhance the strength of the pressure chamber wall member 5, it is preferable to use a material with a Young's modulus of 50 GPa or more for the functional film 9. In general, the Young's modulus of resin is lower than that of metal, etc., and it has been reported that epoxy resin has a Young's modulus of about 2 GPa, and even resins with a large Young's modulus are less than 5 GPa. Therefore, if the Young's modulus of the functional film 9 is 50 GPa, it will be 10 times or more higher than that of resins with a high Young's modulus. Stainless steel, Ni, Ir, Ta, W, Mo, Cr, Co, Fe, Ru, SiC, TiC, WC, B4C, ZrO2, Al2O3, Ta2O5, AlN, Si3N4, TiN, diamond, etc. can be used.

[0039] The functional film 9 can be formed by PVD (physical vapor deposition), ALD (atomic layer deposition) and CVD (chemical vapor deposition). In PVD, sputtering, vacuum deposition, molecular beam epitaxy, laser deposition, electron beam deposition, etc. can be used. In CVD, various methods using heat, plasma, electromagnetic waves, catalysts, etc. can be combined. Alternatively, wet processing such as plating can be used. In addition, the functional film 9 can be formed by combining these film formation methods. After forming the functional film 9, processing using heat, electromagnetic waves, electron beams, plasma, etc. can be performed. In addition, when considering film formation on a fine structure such as the pressure chamber wall member 5 of the present invention, defects may occur due to bubbles in wet processing, and even if the defects are reduced by repeating film formation and cleaning, it is not preferable from the viewpoint of film thickness control. Therefore, it is preferable to use PVD, CVD and ALD, which are less likely to cause defects. Among these, CVD is more preferable from the viewpoint of coverage, and ALD, which has excellent adhesion to the fine structure, is even more preferable. When it is desired to selectively form the functional film 9 on the surface of the nozzle plate 6, PVD, which is a highly directional film formation method, is preferred, and among these, vacuum deposition, molecular beam epitaxy, laser deposition, and electron beam deposition, which are easy to increase the degree of vacuum during film formation, are more preferred.

[0040] Another example of the method for manufacturing a liquid ejection head according to the present invention will be described with reference to Fig. 9. Each of the following steps can be performed using a known technique.

[0041] As shown in Fig. 9(A), a substrate 1 having a piezoelectric element 2 is prepared. In Fig. 9(A), the substrate 1 further has a vibration plate 3, a liquid supply port 4a, and a liquid outlet port 4b.

[0042] 9(B), a first pressure chamber wall member 51 is formed using a photosensitive resin on the substrate 1. Exposure is performed using a mask to form a latent image of a portion 151 that will become the pressure chamber wall member 5.

[0043] 9(C), the second pressure chamber wall member 52 is molded on the first pressure chamber wall member 51 using a photosensitive resin. Exposure is performed using a mask to form a latent image of a portion 152 that will become the pressure chamber wall member 5. Here, in molding the second pressure chamber wall member 52, a photosensitive resin or exposure conditions may be selected using known techniques such that the first pressure chamber wall member 51 is less susceptible to the effects of exposure during the formation of the second pressure chamber wall member 52.

[0044] 9(D), the first nozzle plate member 61 is molded. Exposure is performed using a mask to form a latent image of the portion 161 that will become the nozzle plate. Here, in molding the first nozzle plate member 61, a photosensitive resin or exposure conditions that are less likely to be affected by exposure to light can be selected using known techniques.

[0045] As described above, by using latent image formation by photolithography to form the pressure chamber wall member and the nozzle plate member, the flatness and thickness accuracy of the formed members can be improved more easily than when a mold material is used. It is also possible to form the first pressure chamber wall member 51 and the second pressure chamber wall member 52 as one layer and to fabricate the pressure chamber wall member and the structure 7 by a method of partially changing the exposure conditions. However, variations in the exposure conditions may deteriorate the processing accuracy in the height direction. Therefore, by forming the pressure chamber wall member from two or more layers of photosensitive resin as in the present invention, the processing accuracy of the structure 7 can be improved more easily.

[0046] 9(E), a second nozzle plate member 62 is formed. Exposure is performed using a mask to form a latent image of a portion 162 that will become the nozzle plate. Here, in forming the second nozzle plate member 62, a photosensitive resin or exposure conditions that are unlikely to affect the pressure chamber wall member and the first nozzle plate member 61 due to exposure may be selected using known technology.

[0047] 9(F), the multiple layers are developed all at once to form the pressure chamber wall member 5, the nozzle plate 6, and the structure 7. A functional film 9 may be formed on the pressure chamber wall member 5 and the structure 7 as described above.

[0048] Another example of the method for manufacturing a liquid ejection head according to the present invention will be described with reference to Fig. 10. Each of the following steps can be performed using a known technique.

[0049] As shown in Fig. 10(A), a substrate 1 having a piezoelectric element 2 is prepared. In Fig. 10(A), the substrate 1 further has a vibration plate 3, a liquid supply port 4a, and a liquid outlet port 4b.

[0050] 10(B), a first pressure chamber wall member 51 is formed using a photosensitive resin on the substrate 1. Exposure is performed using a mask to form a latent image of a portion 151 that will become the pressure chamber wall member.

[0051] 10(C), the second pressure chamber wall member 52 is formed. Exposure is performed using a mask to form a latent image of the portion 152 that will become the pressure chamber wall member. Here, in forming the second pressure chamber wall member 52, a photosensitive resin or exposure conditions that will prevent the first pressure chamber wall member 51 from being affected by exposure during the formation of the pressure chamber wall member 52 may be selected using known technology.

[0052] Subsequently, as shown in FIG. 10(D), the multiple layers are developed at once to form the pressure chambers 10 and the structures 7.

[0053] Next, as shown in FIG. 10(E), the nozzle plate 6 is bonded to the pressure chamber wall member 5 using an adhesive 20. At this time, as shown in FIG. 10(E), a recess 30 may be formed in at least one of the pressure chamber wall member 5 and the nozzle plate 61. The recess 30 can be used as an adhesive storage hole for controlling the overflow of the adhesive. By forming the recess 30 in the pressure chamber wall member 5 using a photosensitive resin, it is possible to obtain an effect of improving the dimensional accuracy of the adhesive storage hole. The shape of the recess 30 can be a known shape such as a combination of a circle, an ellipse, a square, a rectangle, a triangle, etc., or a hole or a groove in a shape surrounded by a curve.

[0054] 10(F), the nozzles 11 of the nozzle plate are penetrated. Furthermore, the functional film 9 may be formed on the pressure chamber wall member 5 and the structure 7 as described above.

[0055] Yet another example of the method for manufacturing a liquid ejection head according to the present invention will be described with reference to Figures 11 to 13. Each of the following steps can be performed using a known technique.

[0056] First, as shown in Fig. 11(A), a pressure chamber wall member 5 having a first pressure chamber wall member 51 and a second pressure chamber wall member 52 is formed on a substrate 1 having a piezoelectric element 2, a vibration plate 3, a liquid supply port 4a, and a liquid outlet port 4b. This can be formed by the same process as Figs. 10(A) to (D). Fig. 11(B) is a cross-sectional view taken along line A-A' in Fig. 11(A), and Fig. 11(C) is a plan view of the pressure chamber wall member 5 as viewed from the second pressure chamber wall member 52 side. As shown in Figs. 11(B) and 11(C), a plurality of pressure chambers 10 are arranged adjacent to each other in the short side direction, and a recess 30 is formed in the pressure chamber wall 50.

[0057] Next, as shown in FIG. 12, a functional film 9 is formed on the surfaces of the pressure chamber wall member 5 and the structure 7. FIG. 12(A) is a cross-sectional view along the longitudinal direction of the pressure chamber, and FIG. 12(B) is a cross-sectional view taken along A-A' in FIG. 12(A). The functional film 9 is also formed on the wall surface of the recess 30, thereby obtaining the effect of increasing the strength of the pressure chamber wall member 5. In the subsequent process of joining and processing the nozzle plate 6 to the pressure chamber wall member 5, or in the process of mounting the chips that have been diced into individual pieces, a processing process using plasma processing or a cleaning process may be performed. In this case, the functional film 9 can also be used as a film that protects the pressure chamber wall member 5 from damage that may occur during plasma processing or the like.

[0058] Next, as shown in Fig. 13(A), the nozzle plate 6 is adhered to the pressure chamber wall member 5 using adhesive 20. Note that Fig. 13(A) is a cross-sectional view in a direction along the longitudinal direction of the pressure chamber, and Fig. 13(B) is a cross-sectional view taken along line A-A' in Fig. 13(A).

[0059] In the liquid ejection head of the present invention, ink is supplied from an ink tank outside the head, and further, inside the head, ink is supplied to each pressure chamber 10 and nozzle 11 through liquid supply port 4a. The liquid ejection head of the present invention further has a drive circuit (not shown) on substrate 1 that provides an electric signal for driving each piezoelectric element 2. When an electric signal is provided from the drive circuit to piezoelectric element 2, vibration plate 3 bends toward pressure chamber 10 due to the piezoelectric effect of piezoelectric element 2, and liquid is ejected from nozzle 11.

[0060] In the liquid ejection head of the present invention, the nozzles can be highly integrated. Depending on the application of the liquid ejection head, the more droplets that are ejected at one time, the more preferable it may be. In that case, it is effective to drive two or more piezoelectric elements simultaneously in the liquid ejection head of the present invention. In this case, an integrated circuit is generally used, but due to the influence of the process temperature when forming the piezoelectric element, there may be a manufacturing problem that it is difficult to fabricate the piezoelectric element and the integrated circuit on one substrate, and an increase in cost may be a problem. Therefore, it is preferable to have a common wiring that inputs a driving electric signal to two or more piezoelectric elements. It is preferable to have a common wiring connected to two or more piezoelectric elements, and the number of piezoelectric elements connected to one common wiring is more preferably 10 or more, even more preferably 100 or more, and particularly preferably 1000 or more. In this case, the effect of reducing the number of pads for inputting electric signals can also be obtained.

[0061] <Example> A liquid ejection head having the structure shown in FIG. 4(E) was formed by the process shown in FIG.

[0062] A substrate 1 was formed having a piezoelectric element 2 including PZT (lead zirconate titanate), a drive circuit (not shown), a liquid supply port 4, and a vibration plate 3 having a silicon base material.

[0063] A pressure chamber wall member 5 was formed on the first surface 100 side of the substrate 1 using two layers of photosensitive resin. First, a negative type photosensitive epoxy resin made into a dry film with a thickness of 40 μm was transferred to the first surface 100 as the first pressure chamber wall member 51. Next, exposure was performed using a photomask and PEB (Post Exposure Bake) was performed to form a latent image of the portion that would become the pressure chamber 10. Next, a negative type photosensitive epoxy resin made into a dry film with a thickness of 20 μm was transferred to the first pressure chamber wall member 51 as the second pressure chamber wall member 52. Exposure was performed using a photomask and PEB was performed to form a latent image of the portion that would become the pressure chamber 10 and the structure 7. Then, the first pressure chamber wall member 51 and the second pressure chamber wall member 52 were developed together using an organic solvent. Furthermore, a heat treatment was performed to promote the hardening of the epoxy resin. The width of the pressure chamber walls 50 between the pressure chambers 10 was 10 μm, the width in the short direction of the pressure chamber was 32.5 μm, the width in the long direction was 1000 μm, and the pitch of the pressure chambers 10 was 42.5 μm. The structure 7 was formed at both ends in the long direction using second pressure chamber wall members 52, and the height was 20 μm, which is determined by the film thickness of the second pressure chamber wall member 52, and the width was 40 μm. A 0.5 μm thick Al2O3 film was formed on the pressure chamber wall member 5 as the functional film 9 by ALD, and a 0.5 μm thick Ta2O5 film was further formed thereon.

[0064] Next, the thermosetting epoxy adhesive 20 on the film was transferred to the pressure chamber wall member 5, and the nozzle plate 6 with a part of the nozzle processed therein was joined. Silicon was used for the nozzle plate 6. Furthermore, a mask pattern was formed on the nozzle plate 6 using resist, and then the nozzles 11 were penetrated by dry etching to form a liquid ejection head.

[0065] Also, as a comparative example, a liquid ejection head not having the structure 7 was formed. The components other than the structure 7 were formed in the same manner as the liquid ejection head of the above-mentioned Example. When the liquid ejection heads of the Example and Comparative Example were compared, the liquid ejection head of the Example had a higher dimensional accuracy of the pressure chamber wall 50 than the Comparative Example, and a higher ejection frequency was obtained. [Explanation of symbols]

[0066] 1 Board 2. Piezoelectric element 3 Vibration plate 4 Liquid supply port 5 Pressure chamber wall member 50 Pressure chamber wall 51 first pressure chamber wall member 52 Second pressure chamber wall member 6 Nozzle Plate 7 Structure 8 Profile material 9. Functional membrane 10 Pressure Chamber 11 Nozzle

Claims

1. A liquid discharge head comprising a nozzle plate provided with a nozzle for discharging a liquid, and a substrate having a piezoelectric element configured to generate a pressure for discharging the liquid from the nozzle. It includes a wall member formed of resin provided between the nozzle plate and the substrate and constituting a pressure chamber communicating with the nozzle. A liquid discharge head, characterized in that a structure configured to connect at least two of a plurality of side surfaces of the wall member forming one of the pressure chambers is provided.

2. The liquid discharge head according to claim 1, wherein the pressure chamber is a space surrounded by the wall member, the nozzle plate, and the substrate.

3. The liquid discharge head according to claim 1, wherein the structure is integrally formed of the same material as the wall member.

4. It has a plurality of the nozzles and a plurality of the pressure chambers provided corresponding to the nozzles. The plurality of the pressure chambers having a substantially rectangular parallelepiped shape are arranged in the short side direction of the pressure chamber. The liquid discharge head according to claim 1, wherein, when viewed in plan from a direction perpendicular to the substrate, the structure continuously connects the wall member between the plurality of pressure chambers in the short side direction of the pressure chamber.

5. It has a plurality of the nozzles and a plurality of the pressure chambers provided corresponding to the nozzles and having a substantially rectangular parallelepiped shape. The liquid discharge head according to claim 1, wherein when the thickness of the wall member between the pressure chambers adjacent to each other in the short side direction of the pressure chamber is L and the height of the pressure chamber in the direction perpendicular to the substrate is T, T / L > 2.

6. The liquid discharge head according to claim 1, wherein, when viewed in plan from a direction perpendicular to the substrate, the structure is arranged at both longitudinal ends of the piezoelectric element having a substantially rectangular shape.

7. Further, a diaphragm is provided between the piezoelectric element and the pressure chamber, In the effective vibration region of the diaphragm corresponding to the pressure chamber and the piezoelectric element, When viewed in plan from a direction perpendicular to the substrate, the ratio of the length of the portion of the effective vibration region in the longitudinal direction that does not overlap with the structure is 30% or more and 90% or less. The liquid ejection head according to claim 1.

8. When viewed in plan from a direction perpendicular to the substrate, the ratio of the length of the portion of the pressure chamber in the longitudinal direction that does not have the structure to the length of the pressure chamber in the longitudinal direction is 90% or less. The liquid ejection head according to claim 1.

9. The substrate has a liquid supply port for supplying liquid to the pressure chamber, When viewed in plan from a direction perpendicular to the substrate, the ratio of the overlapping portion of the structure and the pressure chamber decreases from the liquid supply port side toward the nozzle side, The length of the structure in the longitudinal direction of the pressure chamber is 20% or more of the length of the pressure chamber. The liquid ejection head according to claim 1.

10. The substrate has a liquid supply port for supplying liquid to the pressure chamber and a liquid outlet for allowing the liquid to flow out of the pressure chamber, and is configured such that the liquid circulates between the pressure chamber and the outside of the pressure chamber. The liquid ejection head according to claim 1.

11. With respect to the direction perpendicular to the substrate, the surface of the pressure chamber on the piezoelectric element side is defined as the first surface, and the surface on the nozzle plate side is defined as the second surface, When viewed in plan from a direction perpendicular to the substrate, the first structure and the second structure are arranged at both ends in the longitudinal direction of the piezoelectric element, In the liquid circulation direction, the first structure is provided on the first surface on the liquid supply port side of the nozzle, and the second structure is provided on the second surface. The liquid ejection head according to claim 10.

12. With the surface of the pressure chamber on the piezoelectric element side in the direction perpendicular to the substrate being defined as the first surface, in the liquid circulation direction, the structure is disposed on the first surface on the liquid outlet side, and a part of the nozzle protrudes toward the liquid outlet side beyond the structure on the liquid outlet side. The liquid ejection head according to claim 10.

13. The liquid ejection head according to claim 1, wherein the wall member and the structure are covered with a film made of a material having a Young's modulus of 50 GPa or more.

14. The liquid ejection head according to claim 1, wherein the wall member is composed of two or more layers of resin.

15. The liquid ejection head according to claim 1, wherein the nozzle plate and the wall member are integrally formed.

16. The wall member and the nozzle plate are joined using an adhesive, and at least one of the wall member or the nozzle plate has a recess configured to allow the adhesive to enter. The liquid ejection head according to claim 1.

17. The liquid ejection head according to claim 16, wherein the recess is covered with a film made of a material having a Young's modulus of 50 GPa or more.

18. Further, it has a drive circuit for applying a drive electrical signal for driving each piezoelectric element, and the drive circuit has a wiring for inputting the drive electrical signal common to two or more of the piezoelectric elements. The liquid ejection head according to claim 1.

19. It includes a nozzle plate provided with nozzles for ejecting liquid and a substrate having piezoelectric elements configured to generate pressure for ejecting liquid from the nozzles, and a wall member containing resin provided between the nozzle plate and the substrate and configured to form a pressure chamber communicating with the nozzles. A method for manufacturing a liquid ejection head, characterized in that a structure configured to connect at least two of a plurality of side surfaces of the wall member forming the pressure chamber is provided. A step of forming the piezoelectric element on the substrate; A step of forming the wall member on the substrate using a photosensitive resin; A step of bonding the nozzle plate to the wall member. The method for manufacturing a liquid ejection head, wherein the step of forming the wall member includes a step of molding and exposing a first photosensitive resin, a step of molding and exposing a second photosensitive resin on the first photosensitive resin, and a step of developing the first photosensitive resin and the second photosensitive resin together.

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