JP4033371B2 - Ink jet head, manufacturing method thereof, and image forming apparatus - Google Patents

Description

[0001]
[Industrial application fields]
  The present invention relates to an inkjet head andIts manufacturing method,In particular, an ink jet head having an ink supply path for supplying ink to a pressure chamber, and an image forming apparatusIts manufacturing method,The present invention relates to an image forming apparatus.
[0002]
[Prior art]
As an ink jet head used in an ink jet recording apparatus used as an image recording apparatus such as a printer, a facsimile machine, a copying apparatus, or a plotter, a nozzle for ejecting ink droplets and a pressure chamber (pressure liquid chamber, pressure chamber) communicating with the nozzle are used. A discharge chamber, a liquid chamber, an ink liquid chamber, an ink flow path, etc.) and an energy generating means for generating energy for pressurizing the ink in the pressurizing chamber, and driving the energy generating means. Thus, the ink in the pressurized chamber is pressurized and ink droplets are ejected from the nozzle holes, and an ink-on-demand system that ejects ink droplets only when recording is necessary is the mainstream.
[0003]
Conventionally, as an energy generating means for generating energy to pressurize ink in a pressurizing chamber, a piezoelectric plate is used to deform a diaphragm that forms the wall surface of the pressurizing chamber to change the volume in the pressurizing chamber and eject ink droplets. Ink droplets are ejected with pressure generated by generating bubbles by heating ink in a pressure chamber using a piezo-type device (see Japanese Patent Application Laid-Open No. 2-51734) or a heating resistor. The bubble type (see Japanese Patent Application Laid-Open No. 61-59911), and the diaphragm forming the wall surface of the pressurizing chamber is deformed by electrostatic force to change the volume in the pressurizing chamber and eject ink drops. An electrostatic type device (Japanese Patent Laid-Open No. 6-71882) is known.
[0004]
In these various ink jet heads, an ink supply path is provided for supplying new ink to the pressure chamber from the common ink flow path according to the amount of ink consumed in the pressure chamber. In this case, in order to efficiently use the pressure change in the pressurizing chamber for ink droplet ejection, the ink supply path is formed as a fine hole or groove so as to function as a fluid resistance portion that acts to reduce the backflow of ink. As the head size is reduced and the number of nozzles is increased, the pressure chamber and the ink supply path are required to be miniaturized.
[0005]
Therefore, for example, as disclosed in Japanese Patent Laid-Open No. 6-31914, a Si wafer having a crystal plane orientation (110) and a Si wafer having a given plane orientation or a borosilicate glass substrate are bonded to each other (110 1) A pressurizing chamber is known for a Si wafer having a plane orientation, and a nozzle or an ink supply path is arranged on a Si wafer or a borosilicate glass substrate having an arbitrary plane orientation. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 6-23984, there is known one in which a pressure chamber or an ink supply path is formed by photolithography using a photosensitive material.
[0006]
[Problems to be solved by the invention]
By the way, the ink supply path which is an ink flow path for supplying ink to the pressurizing chamber serves as a fluid resistance portion for preventing the backflow of the ink in the pressurizing chamber when ink droplets are ejected. If it is too large, insufficient ink replenishment to the pressurization chamber will occur when ink droplet ejection is performed at a high frequency, and if the fluid resistance is too small, the ink will flow backward from the pressurization chamber when ejecting ink droplets, resulting in efficiency Ink droplet ejection cannot be performed, and further, mutual interference occurs due to propagation of pressure waves to other pressurizing chambers.
[0007]
For this reason, the ink supply path must be manufactured with high accuracy. However, when the ink supply path is formed in a hole shape (through hole), a small diameter ink supply hole provided for each pressurizing chamber is processed for each hole. So the cost will be high. Therefore, it is conceivable to use photoetching as a method of drilling holes with a large number of micro diameters and micro pitches. However, current photo etching can be processed with less variation if it is a through hole with a diameter similar to the plate thickness. More than that, there is a limit. In addition, although there is electrical discharge machining as a method capable of drilling a small-diameter hole, as described above, a large number of holes cannot be machined at one time, and the time required for machining is extremely long, which is not suitable for mass production. .
[0008]
In addition, as the ink supply path formed in the groove shape, there is an ink jet head as described above. However, the material of the ink jet head in which the ink supply path is arranged on the Si wafer or the borosilicate glass substrate is limited. The
[0009]
In addition, a material using a photosensitive material can form a fine ink flow path, but because of its low rigidity, the liquid chamber interval wall cannot be thinned, and the ink obtained by the displacement of the diaphragm or the heating resistor is used. Since the ejection energy is absorbed by the deformation of the liquid chamber, the energy efficiency is poor and ink cannot be ejected at a high frequency.
[0010]
  The present invention has been made in view of the above-described problems, and has an ink supply path with high accuracy and excellent mass productivity.Its manufacturing method,An object of the present invention is to provide an image forming apparatus provided with the ink jet head.
[0011]
[Means for Solving the Problems]
  In order to solve the above problems, an ink jet head according to the present invention includes a nozzle that ejects ink droplets, a pressure chamber that communicates with the nozzle, and an ink supply that supplies ink to the pressure chamber from a common ink flow path. In the inkjet head having a path, the member that forms the ink supply path is formed to include a plate-shaped member made of metal or ceramics, and the plate-shaped member is formed to penetrate the plate-shaped member, and the pressure chamber side And a groove formed with a substantially circular or elliptical bulge on the common ink flow path side,The groove is a shape formed in the order of one bulging portion, a constricted portion, and the other bulging portion in a direction perpendicular to the thickness direction of the plate-like member,The ink supply path is configured to be connected to the second surface side of the back surface of the first surface of the plate member through a groove formed penetrating from the first surface side of the plate member. In the present specification, the “plate member” is used as a term including a plate member, a film member such as a plating film, or a film member.
[0012]
  here,The groove of the plate-like memberOn the pressurized fluid chamber sideThe bulging portion has a wall surface that extends substantially obliquely with respect to the ink flow direction.Can be configured. In addition, the member that forms the ink supply path is formed by laminating three layers of members, and a groove having a bulging portion is formed in the plate member of the intermediate layer. In this case, the two members sandwiching the plate member of the intermediate layer are preferably made of the same material and have the same thickness.
[0013]
  Also,The plate-like member can be made of a metal material and an oxide film is formed on the surface. Further, the member sandwiching the plate-like member has an opening corresponding to the bulging portion of the groove of the plate-like member, and this opening can be configured not to cover a portion other than the bulging portion of the groove of the plate-like member.
[0014]
  The image forming apparatus according to the present invention is equipped with the ink jet head according to the present invention.
An image forming apparatus.
[0015]
  The method for manufacturing an inkjet head according to the present invention is configured such that in the manufacturing method for manufacturing the three-layered inkjet head, the three-layer laminated member is joined simultaneously.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view of the ink jet head according to the first embodiment of the present invention, and FIG. 2 is an explanatory plan view showing the transparent state of FIG.
[0017]
This ink jet head is provided with a diaphragm 2 on a pressurizing chamber forming plate 1 and a recess 3 for forming a pressurizing chamber on which the diaphragm 2 forms a wall surface, and a piezoelectric element 4 on the outer surface of the diaphragm 2. The actuator part is constituted. On the pressurizing chamber forming plate 1, a fluid resistance forming plate 5, a connection plate 6, a common ink flow path forming plate 7 and a nozzle plate 8 are sequentially laminated to form a plurality of pressurizing chambers 10, Liquid chambers such as a common ink channel (common ink chamber) 11 for supplying ink to the pressurizing chamber 10 and an ink supply channel 12 serving as an ink channel for supplying ink from the common ink channel 11 to the pressurizing chamber 10 Is forming.
[0018]
Here, the ink supply path 12 is formed by laminating three plate-like members of the pressurizing chamber forming plate 1, the fluid resistance forming plate 5, and the connection plate 6. The fluid resistance forming plate 5 which is a plate member of these three intermediate layers is made of, for example, a highly rigid material having a thickness not exceeding 50 μm, and as shown in FIG. ) A planar substantially bone-shaped through-groove having a first opening 15 and a second opening 16 which are bulging portions that are largely open at the end on the pressure chamber 10 side and the end on the common ink flow path 11 side. It is a plate-like member in which (through hole) 13 is formed. That is, the through groove 13 is a groove having a constricted portion that is greatly opened at both ends.
[0019]
  The first opening 15 of the through groove 13 of the fluid resistance forming plate 5 is disposed at a position communicating with the pressurizing chamber 10, and the second opening 16 is disposed at a position communicating with the common ink flow path 11. ThisThe ink supply path 12 passes through a groove 13 formed so as to penetrate from the first surface side of the plate-shaped member, and the first surface (on the connection plate 6 side) of the plate-shaped member (fluid resistance forming plate 5). To the second surface side (surface on the pressurizing chamber forming plate 1 side) of the back surface of the surface.In this case, the first opening 15 communicates with the pressurizing chamber 10 as it is, and the second opening 16 communicates with the common ink flow through the common ink channel communication hole 17 formed of a through hole formed in the connection plate 6. It communicates with the road 11.
[0020]
A plurality of nozzles 18 are formed on the nozzle plate 8 corresponding to the pressure chambers 10, and these nozzles 18 are added to the fluid resistance forming plate 5, the connecting plate 6 and the common ink flow path forming plate 7. A through hole that forms a nozzle communication passage 19 that communicates with the pressure chamber 10 is formed.
[0021]
In the ink jet head configured as described above, when the drive voltage is applied to the piezoelectric element 4, the piezoelectric element 4 expands and contracts, and the vibration plate 2 is deformed and displaced toward the pressurizing chamber 10. The product is decreased, the pressure in the pressurizing chamber 10 is increased, and ink droplets are ejected from the nozzle 18 through the nozzle communication path 19.
[0022]
At this time, the ink in the pressurizing chamber 10 tends to flow into the common ink flow path 11 side through the ink supply path 12, but the ink supply path 12 becomes a fluid resistance and the ink flows into the common ink flow path 11 side. Therefore, efficient ink droplet ejection can be performed.
[0023]
As the ink droplet ejection ends, the ink pressure in the pressurizing chamber 10 decreases, and a negative pressure is generated in the pressurizing chamber 10 due to the inertia of the ink flow and the discharge process of the driving voltage, and the ink filling process proceeds. The pressure chamber 10 is filled with ink through the ink supply path 12 including the common ink flow path communication hole 17 of the connection plate 6 and the through groove 13 of the fluid resistance forming plate 5 from the common ink flow path 11. Then, when the vibration of the ink meniscus surface near the outlet of the nozzle 18 is attenuated and returns to a steady state to some extent, the operation proceeds to the next ink droplet ejection operation.
[0024]
As described above, in this ink jet head, as described above, the member that forms the ink supply path 12 is a bulge that is largely open at the end of the narrow groove 14 at the end of the pressurizing chamber 10 and the end of the common ink channel 11. It includes a fluid resistance forming plate 5 in which a planar substantially bone-shaped through groove 13 having a first opening portion 15 and a second opening portion 16 which are protruding portions is formed, and is formed by the through groove 13 of the fluid resistance forming plate 5. The flow path is at least part of the ink supply path 12.
[0025]
As a result, the slit groove (narrow groove) 14 located at the center of the through groove 13 of the fluid resistance forming plate 5 forms a fluid resistance portion in the ink supply path 12. The fluid resistance of the fluid resistance portion is determined by the thickness of the fluid resistance forming plate 5 and the width and length of the narrow groove 14. When the narrow groove 14 has a rectangular shape with a long side length a and a short side length b, the flow rate Q flowing is Q∝a * b.^ThreeTherefore, it is largely controlled by the short side length b.
[0026]
Therefore, by forming a narrow groove (slit groove) 14 that becomes a fluid resistance portion using a plate-like member (fluid resistance forming plate 5) that is a uniform and thin material, the influence of the variation in the shape of the slit groove can be reduced. An ink supply path that is difficult to receive and has a stable fluid resistance can be obtained. In addition, since the groove width can be made relatively large by using a thin plate, high-precision fine processing can be performed even by etching a metal plate and the cost can be reduced.
[0027]
Here, refer to FIGS. 3 to 5 for the shapes (planar shapes) of the first and second openings 15 and 16 that are bulged portions that are largely opened and formed at both ends of the narrow groove 14 to be the fluid resistance portion. I will explain.
The shape (planar shape) of the first and second openings 15 and 16 can be a planar square shape as shown in FIG. However, in this shape, an angular corner is formed at the connecting portion between the narrow groove 14 and the first and second openings 15 and 16, and bubbles that adversely affect ink droplet ejection characteristics are trapped in the vicinity of the corner. It becomes easy.
[0028]
Therefore, as the shape (planar shape) of the first and second openings 15 and 16, an elliptical shape as shown in FIG. 4 is used, and the connecting portion between the narrow groove 14 and the first and second openings 15 and 16. It is possible to reduce the trapping of bubbles by making it smooth. However, even in this elliptical shape (depending on the groove width and the diameter of the ellipse), the ink flowing into the first opening 15 from the narrow groove 14 is difficult to follow along the wall surface of the opening 15 and a vortex may be generated. Therefore, in the case of an elliptical shape, it is preferable to make at least the major axis in the ink flow direction.
[0029]
More preferable shapes (planar shapes) of the first and second openings 15 and 16 are, as shown in FIG. 5A or 5B, wall surfaces 15a and 16a that spread substantially obliquely with respect to the ink flow direction. Or it has 15b, 16b. That is, it is preferable that the angle θ formed between the narrow groove 14 and the first and second openings 15 and 16 is an obtuse angle, and a delta shape is formed in the vicinity of the inflow of the first opening 15 from the groove 14. With such a shape, the ink flowing into the first opening 15 from the narrow groove 14 is likely to spread as a whole along the wall surfaces 15a and 15a, and the occurrence of bubble traps and vortex flow is extremely reduced.
[0030]
In these cases, the first and second openings 15 and 16 have the same shape, but the first opening 15 on the pressurizing chamber 10 side has a shape as shown in FIG. 5A or 5B, for example. The second openings 16 on the common ink flow path 11 side may have different shapes, such as the shape shown in FIG.
[0031]
Next, the first and second openings 15 and 16, the corresponding opening on the pressure chamber 10 side (here, the opening of the recess 3), and the opening on the common ink flow path 11 side (here, common to the connection plate 6) The positional relationship with the ink channel communication hole 17) will be described with reference to FIG.
As described above, the fluid resistance value due to the narrow groove 14 serving as the fluid resistance portion is determined by the width, thickness, and length of the narrow groove 14, so that the first opening portion 15 is provided as shown in FIG. The corresponding opening position on the pressure chamber 10 side is the end of the narrow groove 14, and similarly the opening position on the common ink flow path 11 side corresponding to the second opening 16 is the end of the narrow groove 14. A fluid resistance having a resistance value determined by the narrow groove 14 can be formed.
[0032]
By the way, when the ink supply path is formed by laminating a plurality of plate-like members as in this embodiment, the displacement of the joining positions of the plate-like members is unavoidable. As described above, the opening on the pressurizing chamber 10 side is shifted from the end of the narrow groove 14 and enters the first opening 15. Similarly, the opening on the common ink flow path 11 side is shifted from the end of the narrow groove 14 and the narrow groove 14. It can happen. In such a state, the length of the narrow groove 14 serving as a fluid resistance changes, and a desired fluid resistance value may not be obtained. As a result, the fluid resistance value varies.
[0033]
Therefore, as shown in FIG. 3C, the opening on the pressurizing chamber 10 side (here, the opening of the recess 3) and the opening on the common ink channel 11 side (here, the common ink channel communication hole 17 of the connecting plate 6). ) Enters the first and second openings 15 and 16 and preferably has a positional relationship that does not cover the portions other than these openings 15 and 16, that is, the central narrow groove 14. And variation can be reduced.
[0034]
Next, in this embodiment, a fluid resistance forming plate 5 having a through groove 13 is sandwiched from above and below between the pressurizing chamber forming plate 1 and the connecting plate 6 to form a three-layer structure. When the ink supply path is formed by stacking the shape members, if the materials of the stacked members are different, warping due to a difference in thermal expansion coefficient or the like is likely to occur due to heating when stacking and joining. .
[0035]
Therefore, when laminating a plurality of plate-like members, it is preferable that all are made of the same material, but when only the plate-like member forming the intermediate layer (here, the fluid resistance forming plate 5) is made of a different material. At the time of joining, two plate-like members sandwiching the intermediate-layer plate-like member (here, the pressure chamber forming plate 1 and the connecting plate 6) are made equal in material and thickness, and the three layers are joined simultaneously. Less warpage.
[0036]
By performing such joining, dissimilar materials can be laminated without warping, and the range of selection of the material for the plate member of the intermediate layer that requires a precise processed shape can be expanded.
[0037]
As a plate-like member serving as an intermediate layer, it is preferable to use a highly rigid material such as metal or ceramics as much as possible. If a low-rigidity material is used for the intermediate layer, the intermediate layer will be crushed when a large pressure is applied during lamination and bonding, and the gap and height of the ink supply path will be narrowed, resulting in non-uniform fluid resistance. Occurs.
[0038]
Therefore, as the plate member of the intermediate layer, a material having a uniform thickness and a thin and high rigidity is most suitable, and examples thereof include metal plates such as stainless steel, copper, phosphor bronze, and nickel. These metal plates are not only inexpensive, but can be processed with high productivity such as etching. In particular, stainless steel is inexpensive because it has high marketability, can be processed by etching and pressing, and is excellent in ink resistance. Also, a nickel-based material can realize a high-quality fine shape by an electroforming method.
[0039]
In the case of using such a metal material, by forming an oxide layer on the surface by heat treatment or acid treatment, ink resistance is improved and wettability is improved, so that adhesion is also improved. In particular, heat treatment is performed not only before joining but also before drilling, so that it is possible to avoid warping during joining due to shape change due to thermal contraction of the metal material and to form a flow path with high dimensional accuracy. it can.
[0040]
Next, a second embodiment of the present invention will be described with reference to FIGS. 7 is an explanatory cross-sectional view of the inkjet head according to the embodiment, and FIG. 8 is an explanatory plan view showing the transparent state of FIG.
[0041]
In this ink jet head, a diaphragm 22 is provided on the lower surface side of a pressurizing chamber forming plate 21 having a through hole for forming a pressurizing chamber, and a laminated piezoelectric element 24 is provided on the outer surface of the diaphragm 22 to provide an actuator portion. It is composed. Further, on the pressurizing chamber forming plate 21, a fluid resistance forming plate 25, a connection plate 26, a common ink flow path forming plate 27, and a nozzle plate 28 are sequentially laminated to form a plurality of pressurizing chambers 30 and a plurality of these pressurizing chambers. A common ink channel (common ink chamber) 31 for supplying ink to the pressurizing chamber 30 and an ink supply channel 32 serving as an ink channel for supplying ink from the common ink channel 31 to the pressurizing chamber 30 are formed. Yes.
[0042]
Here, the ink supply path 32 is formed by laminating three layers of the pressurizing chamber forming plate 21, the fluid resistance forming plate 25, and the connection plate 26 with a plate-like member. As shown in FIG. 8, the fluid resistance forming plate 25, which is an intermediate layer of these three layers, is formed at the end portion on the pressurizing chamber 30 side and the end portion on the common ink flow path 31 side of the narrow groove 34 serving as the fluid resistance portion. This is a plate-like member formed with a planar substantially bone-shaped through-groove (through-hole) 33 having a first opening 35 and a second opening 36 that are bulged portions that are largely open. That is, the through-groove 33 is a groove having a constricted portion that is largely open at both ends.
[0043]
The first opening 35 of the through groove 33 of the fluid resistance forming plate 25 is disposed at a position communicating with the pressurizing chamber 30, and the second opening 36 is disposed at a position communicating with the common ink flow path 31. In this case, the first opening 35 communicates with the pressurizing chamber 30 as it is, and the second opening 36 communicates with the common ink channel 31 through a common ink channel communication hole 37 formed in the connection plate 36. is doing.
[0044]
A plurality of nozzles 38 are formed on the nozzle plate 38 corresponding to the pressure chambers 30, and these nozzles 38 are added to the fluid resistance forming plate 25, the connection plate 26 and the common ink flow path forming plate 27. A nozzle communication path 39 including a through hole communicating with the pressure chamber 30 is formed.
[0045]
Also in this ink jet head, the same effect as the ink jet head of the first embodiment described above can be obtained.
[0046]
Therefore, a more specific embodiment of the present invention will be described below.
Example 1
First, the first embodiment will be described with reference to FIGS. 1 and 2 described above.
This ink jet head relates to the first embodiment. A single crystal Si substrate having a crystal plane orientation (100) is used as the pressurizing chamber forming plate 1, and a thermal oxide film is formed on the Si substrate. The resist is patterned corresponding to the shape of No. 2, and after opening the resist, the Si substrate is etched using a hydrofluoric acid-based etching solution or an aqueous KOH solution, and the recesses 3 to be the pressurizing chamber 10 and the vibrations at the bottom of the recesses 3 Plate 2 was formed. At this time, the thickness of the diaphragm 2 was about 7 μm and the width was 200 μm.
[0047]
Then, zirconia as an intermediate layer for preventing diffusion of lead in the piezoelectric element to the Si substrate is formed on the outer surface side (rear surface side) of the diaphragm 2 by a sputtering method to a thickness of 1 μm, and on the intermediate layer. A platinum electrode having a thickness of 5 μm was formed by a screen printing method. Further, a paste obtained by pasting a calcined powder of a piezoelectric material mainly composed of PZT was screen-printed to a thickness of 20 μm and fired in the atmosphere at a temperature of 900 to 1100 ° C. A silver electrode was patterned on the fired piezoelectric body to form a piezoelectric element 4.
[0048]
On the other hand, a 30 μm-thick Kovar plate was used as the fluid resistance forming plate 5, and the holes for forming the nozzle communication holes 19 having a diameter of 200 μm and the through grooves 13 were formed by etching. As shown in FIG. 3, the through groove 13 has a shape having a constricted portion having first and second openings 15 and 16 which are bulged portions that are widely opened at both ends of a thin slit groove (narrow groove) 14. The openings 15 and 16 at both ends have a substantially circular shape with a diameter of 180 μm, and the central slit portion (thin groove 14) has a width of 60 μm and a length of 300 μm.
[0049]
After the fluid resistance forming plate 5 is plated with gold, it is positioned and superimposed on the pressurizing chamber forming plate 1 made of the Si substrate on which the vibration plate 2 is formed, and heated at 450 ° C. in a nitrogen atmosphere. Were joined. Further, a connection plate 6 having a hole for forming a nozzle communication hole 19 having a diameter of 200 μm and a common ink channel communication hole 17 is formed of a Kovar plate having a thickness of 100 μm, and this connection plate 6 is made of an epoxy adhesive (EP made by Cemedine). -170: trade name) and cured by heating at 110 ° C.
[0050]
Further, a common ink flow path forming plate 7 having a through hole forming the common ink flow path 11 and a through hole forming the nozzle communication hole 19 was formed of a Kovar plate having a thickness of 100 μm and adhered onto the connection plate 6. Finally, a nozzle 18 having a diameter of 30 μm was formed by electroforming nickel, and a nozzle plate 8 having a thickness of 50 μm having a PTFE water-repellent layer formed on the surface thereof was bonded onto the common ink flow path forming plate 7.
[0051]
When an ink jet head of 100 dpi was formed by such a construction method and an ejection experiment was conducted, good printing characteristics could be obtained.
[0052]
(Example 2)
Next, a second embodiment will be described with reference to FIGS. 7 and 8 described above.
This ink jet head relates to the second embodiment described above, and includes a vibration plate 22, a pressurizing chamber forming plate 21, a fluid resistance forming plate 25, a connection plate 26, a common ink flow path forming plate 27, and a nozzle plate 28. It has a six-layer structure that is sequentially stacked. Here, the vibration plate 22 and the nozzle plate 28 are formed by nickel electroforming, and the other pressurizing chamber forming plate 21, fluid resistance forming plate 25, connecting plate 26, and common ink flow path forming plate 27 are etched by stainless steel plate. Formed.
[0053]
In this case, the pressure chamber 30 has a width of about 100 μm, and the nozzle communication path 39 and the common ink flow path communication hole 17 have a diameter of 100 μm. The diaphragm 22 has a substantially rectangular shape, and has a structure in which the periphery of the pressurizing chamber 30 having a length of 2 mm, a width of 40 μm, and a thickness of 30 μm is surrounded by a thin portion having a thickness of 5 μm. For the stainless steel plate, only the fluid resistance forming plate (fluid resistance forming plate) 25 has a thickness of 25 μm, and the pressurizing chamber forming plate 21, the connection plate 26, and the common ink flow path forming plate 27 have a thickness of 100 μm. The through-groove 33 of the fluid resistance forming plate 25 has a shape in which first and second openings 35 and 36 which are substantially circular holes having a diameter of 100 μm provided at both ends are connected by a narrow groove 34 having a width of 60 μm and a length of 200 μm. did.
[0054]
These plate-like members are made of polyimide-based adhesive having excellent long-term reliability with respect to the ink in the order of the pressure chamber forming plate 21 -the fluid resistance forming plate 25 -the connecting plate 26 -the nozzle plate 27 -the vibrating plate 22 in this order. When the laminated piezoelectric element 24 as an actuator for driving the vibration plate 22 is bonded at 210 ° C. and a pressure of 100 kgf / cm 2, the first pressurizing chamber forming plate 21 and the fluid resistance forming plate 25 are joined. Bonding caused a warp of 500 μm or more on the plate, which hindered subsequent bonding.
[0055]
Therefore, it is presumed that the curing temperature of the used adhesive is as high as 200 ° C. or higher and the difference in thermal shrinkage due to the difference in thickness between the pressurizing chamber forming plate 21 and the fluid resistance forming plate 25. When the pressurizing chamber forming plate 21, the fluid resistance forming plate 25 and the connection plate 26 are joined at the same time, and the thin fluid resistance forming plate 25 is joined between the thick pressurizing chamber forming plate 21 and the connecting plate 26, after joining. Was reduced to about 100 μm.
[0056]
Furthermore, when heat treatment was performed at 300 ° C. before applying the adhesive to the pressurizing chamber forming plate 21, the fluid resistance forming plate 25, and the connection plate 26, the pressurizing chamber forming plate 21, the fluid resistance forming plate 25, and The joint surface of the connection plate 26 was oxidized, the adhesive could be applied more uniformly, and the adhesive strength was improved. In addition, the warpage amount of the plate after bonding was reduced to about 50 μm, and all the layers (plate-like members) could be bonded well.
[0057]
As a comparative experiment, when the liquid chamber part was immersed in an aqueous ferric chloride solution for several minutes, the effect of increasing the adhesive strength was obtained.
[0058]
Further, a plate-like member in which a fluid resistance forming plate 25 having a higher precision shape is formed by nickel electroforming, and a plate-like member in which a through groove is formed in a polyimide film by excimer laser processing are joined in a sandwich state by the above method. As a result, it was possible to bond well.
[0059]
An ink jet head using the fluid resistance forming plate 25 made of these three kinds of materials was manufactured, and its ejection characteristics were evaluated. As a result, in the case of the head having the fluid resistance forming plate 25 using the polyimide film, the characteristic variation between the channels was slightly large. This is because the pressure at the time of bonding is large and may be caused by the crushing of the fluid resistance forming plate 25. For confirmation, the fluid resistance forming plate 25 is sandwiched between glass plates and heated and pressurized under the same conditions. As a result of observing the fluid resistance portion (narrow groove 34) after curing, it was confirmed that the narrow groove had non-uniform deformation and the gap height was non-uniform. Therefore, the curing pressure is 7 kgf / cm.²When the same observation was made after switching to an adhesive of a degree, it was confirmed that the polyimide film was not deformed and the jetting characteristics were stable.
[0060]
On the other hand, a head using a stainless steel plate or a nickel electroformed plate as the fluid resistance forming plate 25 was similarly observed, and it was confirmed that there was no deformation of the fluid resistance portion. Thus, whether or not the fluid resistance portion undergoes a level of deformation that affects the ejection characteristics depends on conditions such as the adhesive used and the shape of the liquid chamber, but increases the rigidity of the fluid resistance forming plate 25. As a result, the condition is relaxed, and as a result, it is understood that the margin for selection of the adhesive and the like is widened and preferable.
[0061]
(Example 3)
Next, the third embodiment will be described with reference to FIGS. 7 and 8 as in the second embodiment. In this ink jet head, the fluid resistance forming plate 25 of Example 2 was formed of a nickel plate having a thickness of 30 μm. In order to find the relationship between the shapes of the first and second openings 35 and 36 forming the ink supply path 32 and the ink droplet ejection characteristics, the shapes of the first and second openings 35 and 36 are shown in FIG. A plurality of heads having the shape shown in FIG. 5A were manufactured and evaluated.
[0062]
First, as shown in FIG. 3, the fluid resistance forming plate 25 in which the through-groove 33 having the slit groove (narrow groove) 34 having the square holes as the openings 35 and 36 is formed by electroforming. Then, when each plate-like member was joined with an epoxy adhesive and an ink ejection experiment was conducted, a large number of channels where ink was not ejected were generated.
[0063]
In order to analyze this factor, a glass plate was attached instead of the diaphragm 32, and when the ink flow was observed when ink was injected, bubbles were found at the corners of the square holes (openings 35 and 36) at both ends. For this reason, ink supply is not performed stably, or bubbles are mixed into the pressure chamber and ink discharge pressure is used to change the volume of the bubbles. It was confirmed that discharge was not possible.
[0064]
Therefore, the fluid resistance forming plate 25 in which the openings 35 and 36 have an elliptical shape as shown in FIG. 4 was similarly manufactured by electroforming, and an ink jet head was constituted to perform jetting evaluation. As a result, good results were obtained for ink droplet ejection in the low frequency driving region, but the ejection characteristics became unstable when ink droplets were ejected by high frequency driving.
[0065]
In order to analyze this factor, in the same manner as described above, a glass plate was joined instead of the vibration plate 22 to inject ink, and the ink flow inside the liquid chamber was observed. As a result, when the flow rate of the ink is large, it is observed that a vortex is generated at the connection portion with the slit groove (thin groove 34) of the opening 35 on the pressurizing chamber side. It was estimated that the ink supply of the ink was unstable.
[0066]
Therefore, the openings 35 and 36 are shaped so that the speed change of the ink flow at the entrance and exit of the narrow groove (slit groove) 34 becomes relatively smooth as shown in FIG. As a taper shape having a wall surface 15a that extends obliquely from the angle, the angle θ between the connecting portions of the narrow groove 34 and the openings 35 and 36 at both ends is made obtuse, so that the generation of vortices can be prevented even when the ink flow rate is large. It was confirmed that ink droplets could be discharged well at high frequencies.
[0067]
In this case, the size of the angle θ depends on other conditions such as the slit width (groove width), the size of the opening, and the driving frequency, but with the frequency of about 12 kHz in the ink jet head in the configuration of this embodiment. In the case of ejecting ink, the angle should be at least 90 °, more preferably 135 ° or more.
[0068]
Also, instead of the method of forming the linear tapered wall surface shown in the present embodiment and connecting the slit groove and the opening, the shape having a smoother wall surface as shown in FIG. A similar effect can be obtained if the ink flow rate is changed.
[0069]
Example 4
Next, the fourth embodiment will be described with reference to FIGS. 7 and 8 as in the second embodiment.
In this ink jet head, the fluid resistance forming plate 25 is formed of a stainless plate having a thickness of 30 μm. A plurality of heads were manufactured in order to evaluate the positional relationship between the first and second openings 35 and 36 provided in the fluid resistance forming plate 25 and the opening of the pressurizing chamber forming plate 31 and the opening of the connection plate 36. .
[0070]
First, three sheets for forming the ink supply path so that the opening of the pressurizing chamber forming plate 21 and the opening of the connecting plate 26 are located at the end of the slit groove (narrow groove) 34 as shown in FIG. The hole position of the plate was determined, the head was assembled, and jetting evaluation was performed. As a result, it has been found that the ejection speed of ink droplets varies within the head.
[0071]
The assembly accuracy of the head subjected to this evaluation was ± 15 μm, and it was estimated that the fluid resistance length varied due to the misalignment at the time of stacking as shown in FIG.
[0072]
Therefore, as shown in FIG. 6C, the opening of the pressurizing chamber forming plate 21 and the opening of the connecting plate 26 are aligned from the end of the slit groove (narrow groove 34) as shown in FIG. When the hole position is determined at a position separated by 30 μm / min and the head is configured by laminating as before, and the ejection evaluation is performed, the variation in ejection characteristics within the head is reduced, and good results are obtained. It was.
[0073]
Accordingly, when a plurality of plate-like members are stacked, the positional relationship between the opening of the groove of the plate-like member of the intermediate layer and the opening of the plate-like member sandwiching the intermediate layer is determined by It can be seen that a highly accurate fluid resistance can be formed by securing an alignment margin by adopting a positional relationship in which the opening does not cover a portion other than the opening of the groove of the plate member of the intermediate layer.
[0074]
  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to a piezo ink jet head. However, the present invention is applied to other types of ink jet heads such as electrostatic ink jet heads and bubble jet (registered trademark) ink jet heads. Can be applied similarly. Moreover, although the groove | channel was demonstrated in the example which is a through-groove, the whole can also be made into a groove | channel with a bottom, or it can also be made into the groove | channel which only a bulging part is a through-hole. Further, although an example in which the bulging portion (opening portion) is provided on the pressure chamber side and the common ink flow path side has been described, the bulging portion may be provided only on one side. By providing the bulging part on the pressure chamber side and the common ink flow path side, the fluid resistance part can be completed with a groove, and a more accurate ink supply path can be obtained.Further, as described above, the ink jet head according to the present invention can be mounted on an image forming apparatus (image recording apparatus) such as a printer, a facsimile, a copying apparatus, or a plotter.
[0075]
【The invention's effect】
  As described above, according to the inkjet head of the present invention, the member that forms the ink supply path is formed including a plate-like member made of metal or ceramics, and the plate-like member penetrates the plate-like member. Formed in the pressurizing chamber side and the common ink flow path side, and has a groove formed with a substantially circular or elliptical bulge,The groove is a shape formed in the order of one bulging portion, a constricted portion, and the other bulging portion in a direction perpendicular to the thickness direction of the plate-like member,Since the ink supply path is connected to the second surface side of the back surface of the first surface of the plate member through the groove formed penetrating from the first surface side of the plate member. A highly accurate ink supply path can be formed.
[0076]
  here,The groove of the plate-like memberOn the pressurized fluid chamber sideThe bulging portion has a wall surface that extends substantially obliquely with respect to the ink flow direction.ConfigureAs a result, it is possible to prevent bubbles from staying and generating vortices, and to perform stable ink droplet ejection with little variation.In addition, the member that forms the ink supply path is formed by stacking three layers of members, and a groove having a bulging portion is formed in the plate member of the intermediate layer, so that a highly accurate ink supply path is formed. Can be easily formed. In this case, the two members sandwiching the plate member of the intermediate layer can be made of the same material and have the same thickness, so that a liquid chamber member having high flatness can be formed.
[0077]
  Also,The plate-like member is made of a metal material, and the bonding property can be improved by adopting a structure in which an oxide film is formed on the surface. In addition, the member sandwiching the plate-like member has an opening corresponding to the bulging portion of the groove of the plate-like member, and the opening does not cover a portion other than the bulging portion of the groove of the plate-like member. Thus, it is possible to prevent a change in the resistance value of the fluid resistance portion due to misalignment during joining, and to form a highly accurate fluid resistance portion.
[0078]
  According to the image forming apparatus of the present invention, since the ink jet head according to the present invention is mounted, stable ink droplet ejection can be performed.
[0079]
  According to the method for manufacturing an inkjet head according to the present invention, in the manufacturing method for manufacturing a three-layered inkjet head, the three-layer laminated member is bonded at the same time, so that the planarity and bondability are improved.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view of an inkjet head according to a first embodiment of the invention.
FIG. 2 is an explanatory plan view showing the transparent state of FIG.
FIG. 3 is an explanatory diagram showing an example of a planar shape of an opening of a groove
FIG. 4 is an explanatory view showing another example of the planar shape of the opening of the groove.
FIG. 5 is an explanatory diagram showing still another example of the planar shape of the groove opening.
FIG. 6 is an explanatory diagram for explaining the positional relationship between a groove opening and a corresponding opening.
FIG. 7 is a cross-sectional explanatory diagram of an inkjet head according to a second embodiment of the invention.
FIG. 8 is an explanatory plan view showing the transparent state in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,21 ... Pressurization chamber formation board, 2,22 ... Vibration board, 4,24 ... Piezoelectric element, 5,25 ... Fluid resistance formation board, 6,26 ... Connection board, 7, 27 ... Common ink flow path formation board 8, 28 ... Nozzle plate, 10, 30 ... Pressurized liquid chamber, 11, 31 ... Common ink flow path, 12, 32 ... Ink supply path, 13, 33 ... Through groove, 14, 34 ... Fine groove, 15, 35 ... 1st opening part, 16, 36 ... 2nd opening part, 17, 37 ... Common ink flow path communication hole, 18, 38 ... Nozzle, 19, 39 ... Nozzle communication path.

Claims (8)

In an inkjet head having a nozzle that ejects ink droplets, a pressure chamber that communicates with the nozzle, and an ink supply path that supplies ink to the pressure chamber from a common ink flow path.
The member forming the ink supply path is formed including a plate-like member made of metal or ceramics,
The plate-like member is formed through the plate-like member, and has a groove in which a substantially circular or elliptical bulge is formed on the pressure chamber side and the common ink channel side,
The groove has a shape formed in the order of one bulging portion, a constricted portion, and the other bulging portion in a direction perpendicular to the thickness direction of the plate-like member,
The ink supply path is connected from the first surface side of the plate-like member to the second surface side of the back surface of the first surface of the plate-like member via the groove formed through the penetrating member. An inkjet head characterized by that.   2. The ink jet head according to claim 1, wherein the bulging portion of the groove of the plate-like member on the pressurized liquid chamber side has a wall surface that extends substantially obliquely with respect to the ink flow direction. head.   3. The ink jet head according to claim 1, wherein the member forming the ink supply path is formed by stacking three layers of members, and a groove having the bulging portion is formed in a plate-like member of the intermediate layer. An inkjet head characterized by being made.   4. The ink jet head according to claim 3, wherein two members sandwiching the plate member of the intermediate layer are made of the same material and have the same thickness.   5. The ink jet head according to claim 1, wherein the plate-like member is made of a metal material, and an oxide film is formed on a surface thereof.   6. The ink jet head according to claim 1, wherein a member sandwiching the plate-like member has an opening corresponding to a bulging portion of a groove of the plate-like member, and the opening is formed on the plate-like member. An ink jet head characterized by not covering a portion other than a bulging portion in a groove.   An image forming apparatus comprising the ink jet head according to claim 1.   5. The method for manufacturing an ink-jet head according to claim 3, wherein the three-layer laminated member is joined at the same time.

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