Liquid discharge head and liquid discharge device

Abstract

To provide a liquid discharge head that can suppress fluid crosstalk and a liquid discharge device.SOLUTION: A liquid discharge head 1 includes: a plurality of nozzles 2 for discharging the same liquid; a plurality of individual flow passages 4 which communicate with each of the plurality of nozzles 2; and piezoelectric elements 5 to be a plurality of actuators provided in each nozzle forming wall of the plurality of individual flow passages 4. Cross-sectional area of an opening 4a to be a liquid introduction section which is positioned on a side facing nozzle forming walls of the individual flow passages 4 and into which liquid is introduced from a common flow passage 3 is smaller than cross sectional area on the nozzle forming wall side of the individual flow passage 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid ejection head and an apparatus for ejecting a liquid.

Background Art

[0002] Conventionally, there has been known a liquid ejection head including a plurality of nozzles for ejecting a liquid, a plurality of individual flow paths respectively communicating with the plurality of nozzles, and a plurality of actuators respectively provided on nozzle forming walls of the plurality of individual flow paths, and driving the actuators to eject the liquid in the individual flow paths from the nozzles.

[0003] Patent Document 1 describes that when viewed from a direction orthogonal to both the arrangement direction of the plurality of nozzles and the liquid ejection direction, the width of the nozzle forming wall side of the plurality of individual flow paths is the same as the width of the liquid introduction portion from which the liquid is introduced from the common liquid chamber located on the side opposite to the nozzle forming wall.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, due to the vibration of the actuator provided on the nozzle forming wall in the liquid ejection direction, a liquid flow is generated in the individual flow path toward the liquid introduction portion, and there is a risk of backflow into the common flow path through the liquid introduction portion. The liquid that has flowed back into the common flow path may affect the flow of the liquid into the liquid introduction portion of another individual flow path, and there has been a risk of so-called fluid crosstalk occurring, which disturbs the ejection of the liquid.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention provides a liquid discharge head including a plurality of nozzles that discharge a liquid, a plurality of individual flow paths that communicate with the plurality of nozzles respectively, and a plurality of actuators provided on each nozzle forming wall of the plurality of individual flow paths, the actuators being driven to discharge the liquid in the individual flow paths from the nozzles, wherein a cross-sectional area of a liquid introduction portion that is located on a side facing the nozzle forming wall of the individual flow path and into which the liquid is introduced from a common flow path is smaller than a cross-sectional area of the individual flow path on the nozzle forming wall side.

Effects of the Invention

[0006] According to the present invention, fluid crosstalk can be suppressed.

Brief Description of the Drawings

[0007]

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Best Mode for Carrying Out the Invention

[0008] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. It should be noted that those skilled in the art can easily make changes and modifications to the present invention within the scope of the claims to form other embodiments, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode in this invention and does not limit the scope of the claims.

[0009] The liquid discharging head in the present embodiment is a nozzle plate vibration type liquid discharging head that discharges the liquid in the individual flow path from the nozzle by varying the pressure of the individual flow path by an actuator provided on a nozzle plate having nozzles. The nozzle plate vibration method has a feature that droplets can be ejected with a smaller force compared to a general unimorph type piezo head (which discharges liquid by vibrating the surface facing the wall portion (nozzle forming wall) where the nozzles of the pressure chamber communicate), and power saving of the actuator can be achieved.

[0010] FIG. 1 is a cross-sectional view schematically showing the nozzle plate vibration type liquid discharging head in the present embodiment. FIG. 2 is a perspective view schematically showing the nozzle surface of the liquid discharging head of the present embodiment. The liquid ejection head 1 includes a nozzle plate 110, an individual flow path substrate 100, and a common flow path substrate 120.

[0011] The nozzle plate 110 that forms the nozzle forming walls of the individual flow paths is in a thin film shape and has a plurality of nozzles 2 that eject liquid, and piezoelectric elements 5 as electromechanical conversion elements that are annular actuators arranged around the nozzles 2. The individual flow path substrate 100 has a plurality of individual flow paths 4 that communicate with the plurality of nozzles 2 respectively. There is a nozzle 2 on one surface of each individual flow path 4, and an opening 4a that is a liquid introduction part of the individual flow path is arranged on the side opposite to the one surface. The common flow path substrate 120 has a common flow path 3 that communicates with the plurality of individual flow paths 4. Electric connection pads 6 for connecting to electrical components such as an external power source are provided at both ends of the liquid ejection head 1.

[0012] The individual flow path substrate 100 is an SOI (Silicon on Insulator) substrate having an active layer 100a and a BOX layer 100b, and has a CMOS (complementary metal-oxide semiconductor) 101 as a drive circuit and a wiring layer 102 on the side where the vibration film 103 is formed. The CMOS 101 is provided at both ends of the individual flow path substrate 100 and is a circuit including transistors, resistors, and the like. The wiring layer 102 has a wiring part for applying a drive waveform to the first electrode 51 of the piezoelectric element 5 and a wiring part for applying a drive waveform to the second electrode 53 of the piezoelectric element 5. Also, the wiring layer 102 is electrically connected to the electric connection pad 6 via a third contact 7c formed in the vibration film 103. Further, the wiring layer 102 has the part that forms the wall part of the individual flow path removed in order to facilitate the stress control of the vibration film 103.

[0013] By incorporating the CMOS 101 into the individual flow path substrate 100, the mounting process of the drive circuit using a separate substrate can be reduced, and the area of the external connection part can also be reduced, which leads to the miniaturization of the head. Note that when the CMOS 101 is not built in the individual flow path substrate 100, the individual flow path substrate 100 may be an SI substrate, and the wiring layer 102 is also unnecessary.

[0014] The nozzle plate 110 has a nozzle forming portion (film) 111 in which a plurality of nozzles 2 are formed and which covers the piezoelectric element 5. A liquid-repellent film may be formed on the nozzle surface of this nozzle forming portion 111. By forming a liquid-repellent film on the nozzle surface, it is possible to suppress the adhesion of liquid to the nozzle surface and suppress the influence of the liquid discharged from the nozzle 2 being affected by the liquid adhering to the nozzle surface.

[0015] The piezoelectric element 5 of the nozzle plate 110 has a first electrode 51 (also referred to as a lower electrode), a piezoelectric film 52, and a second electrode 53 (also referred to as an upper electrode). The piezoelectric element 5 is covered with a first insulating film 8a. The first insulating film 8a is formed with a hole-shaped first contact 7a for making an electrical connection to the first electrode 51 and a hole-shaped second contact 7b for making an electrical connection to the second electrode 53.

[0016] Also, a first lead wiring 9a and a second lead wiring 9b are formed on the nozzle plate 110. The first lead wiring 9a electrically connects the first electrode 51 of the piezoelectric element 5 and the wiring layer 102 of the individual flow path substrate 100. The second lead wiring 9b electrically connects the second electrode 53 of the piezoelectric element 5 and the wiring layer 102 of the individual flow path substrate 100.

[0017] The first lead wiring 9a is electrically connected to the first electrode 51 via the first contact 7a and electrically connected to the wiring layer 102 via the fourth contact 7d. The second lead wiring 9b is electrically connected to the second electrode 53 via the second contact 7b and electrically connected to the wiring layer 102 via the fifth contact 7e. The first lead wiring 9a and the second lead wiring 9b are covered with a second insulating film 8b. In the present embodiment, the second insulating film 8b also covers the piezoelectric element 5 and has a function of protecting the piezoelectric element 5 by preventing moisture that has entered the resin-made nozzle forming portion 111 from entering the piezoelectric element 5.

[0018] Note that lead-out wiring portions may be provided on the first electrode 51 and the second electrode 53, respectively, and they may be electrically connected directly to the wiring layer 102 through the contacts 7d and 7e formed in the vibration film 103. Further, an adhesion improvement film for ensuring adhesion with the nozzle forming portion 111 may be formed on the second insulating film 8b.

[0019] The liquid filled in the liquid ejection head 1 enters the nozzle 2 and forms a meniscus inside the nozzle. By applying a predetermined drive waveform (voltage) to each of the electrodes 51 and 53 of the piezoelectric element 5, the piezoelectric film 52 vibrates, and the vibration film 103 vibrates in the vertical direction in FIG. 1. When the vibration film 103 vibrates, a pressure change occurs in the liquid in the individual flow path, and the liquid is ejected from the nozzle 2.

[0020] The individual flow path 4 has a round hole shape, and the inner diameter gradually increases from the opening 4a toward the nozzle plate side. The inner diameter of the opening 4a as the liquid introduction portion through which the liquid is introduced from the common flow path 3 of the individual flow path 4 is smaller than the inner diameter on the nozzle forming wall (nozzle plate 110) side of the individual flow path. Therefore, as shown in FIG. 1, when viewed from a direction orthogonal to the liquid ejection direction, the width Wt of the opening 4a is narrower than the width Wb on the nozzle plate side, and the cross-sectional area of the opening 4a is smaller than the cross-sectional area on the nozzle plate side of the individual flow path 4. The width Wb on the nozzle plate side corresponds to the width of the vibrating portion of the vibration film 103 of the individual flow path 4, and the cross-sectional area on the nozzle plate side corresponds to the cross-sectional area of the vibrating portion of the vibration film 103 of the individual flow path 4. Thus, since the cross-sectional area of the opening 4a is smaller than the cross-sectional area on the nozzle plate side (vibrating portion cross-sectional area) of the individual flow path 4, the flow path resistance of the opening 4a can be increased compared to the case where the cross-sectional areas are the same between the opening 4a and the nozzle plate side. Therefore, the flow rate of the liquid passing through the opening 4a can be reduced, and the liquid in the individual flow path flowing toward the opening 4a can be suppressed from flowing back to the common flow path 3 through the opening 4a due to the vertical vibration of the piezoelectric element 5 in the figure. As a result, fluid crosstalk can be suppressed.

[0021] The shape of the individual flow path 4 is not limited to a round hole shape, and may be rectangular when viewed from the liquid discharge direction. Further, in the rectangular individual flow path, of the two directions orthogonal to the liquid discharge direction, when viewed from either one of the directions, the width Wt of the opening 4a may be made narrower than the width of the width Wb on the nozzle plate side, and the cross-sectional area of the opening may be made smaller than the cross-sectional area on the nozzle plate side.

[0022] Further, it is sufficient that the cross-sectional area of the opening 4a is smaller than the cross-sectional area on the nozzle plate side. For example, the side wall of the individual flow path 4 may be stepped so that the width gradually increases toward the nozzle plate side. However, as shown in FIG. 1, by making the shape such that the width gradually increases from the opening 4a of the individual flow path 4 toward the nozzle plate side, as will be described later, the cross-sectional area of the opening 4a can be made as small as possible with respect to the cross-sectional area on the nozzle plate side in the processing by the Bosch process, which is preferable.

[0023] Further, as shown in FIG. 1, it is preferable that the width Wt of the opening 4a is made narrower than the width Ws of the piezoelectric element 5 as an actuator, and the cross-sectional area of the opening 4a is made smaller than the cross-sectional area of the piezoelectric element 5. As shown in FIG. 1, the width Ws of the piezoelectric element 5 is generally made narrower than the width Wb on the nozzle plate side corresponding to the vibrating portion of the individual flow path 4, and the cross-sectional area of the piezoelectric element 5 is smaller than the cross-sectional area on the nozzle plate side of the individual flow path 4. Therefore, by making the cross-sectional area of the opening 4a smaller than the cross-sectional area of the piezoelectric element 5, the flow path resistance of the opening 4a can be further increased, and the flow rate of the liquid passing through the opening 4a can be further decreased. As a result, the liquid in the individual flow path flowing toward the opening 4a can be further suppressed from flowing back to the common flow path 3 through the opening 4a due to the vibration of the piezoelectric element 5 in the vertical direction in the drawing. As a result, fluid crosstalk can be further suppressed.

[0024] Next, a method for manufacturing the liquid discharge head of the present embodiment will be described. FIGS. 3 to 12 are cross-sectional views showing a cross-section orthogonal to the arrangement direction of the nozzle holes for explaining the manufacturing process of the liquid discharge head of the present embodiment.

[0025] First, as shown in FIG. 3, a CMOS 101 as a drive circuit including transistors, resistors, etc. and a wiring layer 102 are formed on an individual flow path substrate 100 made of an SOI substrate having an active layer 100a and a BOX layer 100b. The wiring layer 102 is formed by a damascene method or the like, and the steps of forming and patterning SiO2 to create grooves, filling the grooves with wiring metal, and covering the top with SiO2 are repeated. Specifically, it is planarized by CMP polishing, and the film formation and patterning of SiO2 are repeated again. Thereby, a three-dimensional fine wiring can be constructed.

[0026] Next, as shown in FIG. 4, the wiring layer 102 corresponding to the location where the piezoelectric material is to be patterned is removed to form a diaphragm 103. The reason for removing the wiring layer 102 corresponding to the location where the piezoelectric material is to be patterned is stress control of the diaphragm 103. The SiO2 of the wiring layer 102 is difficult to control the stress of the diaphragm 103 because it undergoes multiple SiO2 film formation and polishing steps as described above. Therefore, the wiring layer 102 corresponding to the location where the piezoelectric material is to be patterned is removed to form the diaphragm 103. Note that when stress control is not required, the wiring layer 102 is used as the diaphragm 103, and the formation of the diaphragm 103 is not necessary.

[0027] The material of the diaphragm 103 may be at least an insulating substance such as SiO2, SiN, metal oxide, or resin. However, in order to increase the displacement, a material with a low Young's modulus is desirable, and considering the difference in the linear expansion coefficient from the individual flow path substrate 100, SiO2 with a relatively small difference is most desirable as the material of the diaphragm 103.

[0028] Next, as shown in FIG. 5, a first electrode layer 151, a piezoelectric layer 152, and a second electrode layer 153 are formed on the diaphragm 103. For the first electrode layer 151 and the second electrode layer 153, a metal with low electrical resistance and low reactivity is desirable, and metals such as Pt, Ir, and Mo are desirable.

[0029] Examples of the piezoelectric material constituting the piezoelectric layer 152 include PZT, AlN, etc. When the CMOS 101 and the wiring layer 102 are incorporated in the individual flow base substrate 100 for density improvement, a piezoelectric material with a film formation temperature of 450 °C or lower is desirable so as not to damage them, and AlN with a film formation temperature of 450 °C or lower is preferred.

[0030] Also, by using AlN as the piezoelectric material, the following advantages can be obtained. That is, the piezoelectric characteristics can be improved by aligning the crystal orientation of the piezoelectric film 52. In some cases, an orientation control layer may be provided between the vibration film 103 and the first electrode 51 for the orientation control. When the piezoelectric material of the piezoelectric film 52 is AlN, by using AlN also as the orientation control layer, the lattice constant of the first electrode 51 made of Mo can be made closer to that of AlN. As a result, the crystal orientation of the piezoelectric film 52 is aligned, and the improvement of the piezoelectric characteristics becomes possible.

[0031] For the film formation of the first electrode layer 151, the piezoelectric layer 152, and the second electrode layer 153, a sputtering method or a sol-gel method can be used. Since the latter has a high film formation temperature, when a drive circuit and a wiring part are incorporated in the individual flow base substrate 100, it is desirable to perform film formation using the sputtering method.

[0032] After the first electrode layer 151, the piezoelectric layer 152, and the second electrode layer 153 are formed, as shown in FIG. 6, they are formed into a suitable shape to obtain the piezoelectric element 5 composed of the first electrode 51, the piezoelectric film 52, and the second electrode 53. By processing the first electrode layer 151, the piezoelectric layer 152, and the second electrode layer 153 by photolithography and etching, the first electrode 51, the piezoelectric film 52, and the second electrode 53 of a desired shape can be easily obtained. There are wet etching and dry etching for etching, but the latter is preferred because it can suppress the corrosion of the electrodes 51, 53 and the piezoelectric film 52. Since residues are likely to remain after dry etching, a cleaning process may be added after forming to remove the residues.

[0033] After forming the first electrode 51, the piezoelectric film 52, and the second electrode 53, as shown in FIG. 7, the first insulating film 8a is formed. The first insulating film 8a has insulation properties similar to those of the diaphragm 103. Since it is desirable that the first insulating film 8a has a small Young's modulus and a linear expansion coefficient close to that of the constituent materials, it is preferable to use the same SiO2 as that of the diaphragm 103. Further, a very thin metal oxide may be used as the material of the first insulating film 8a to improve reliability.

[0034] After forming the first insulating film 8a, as shown in FIG. 7, the hole-shaped first contact 7a and second contact 7b are formed in the first insulating film 8a by photolithography and etching. Further, hole-shaped third contact 7c, fourth contact 7d, and fifth contact 7e are formed in the diaphragm 103.

[0035] Next, as shown in FIG. 8, the first lead wiring 9a, the second lead wiring 9b, and the electrical connection pad 6 are formed. Although Al or an AlCu alloy is generally used as the material of each lead wiring 9a, 9b, a noble metal can also be used to improve reliability. In this step, the first lead wiring 9a is electrically connected to the first electrode 51 through the first contact 7a and electrically connected to the wiring layer 102 through the fourth contact 7d. Further, the second lead wiring 9b is electrically connected to the second electrode 53 through the second contact 7b and electrically connected to the wiring layer 102 through the fifth contact 7e. Also, the electrical connection pad 6 is electrically connected to the wiring layer 102 through the third contact 7c.

[0036] Next, as shown in FIG. 9, the second insulating film 8b is formed so as to cover each of the lead wirings 9a, 9b, the piezoelectric element 5, and a part of the electrical connection pad 6. The second insulating film 8b may also use SiO2 similar to the first insulating film 8a, but in order to improve reliability against humidity, it is desirable to use SiN having moisture-proof properties, which is widely used as a semiconductor protective film. By having the two functions of insulation and moisture-proof properties as the second insulating film 8b, the nozzle plate 110 can be made thinner than the case where a moisture-proof protective film is formed on the second insulating film 8b. In the above steps, the piezoelectric element 5 can be driven.

[0037] Next, as shown in FIG. 10, a nozzle forming portion 111 for forming a nozzle is formed. The nozzle forming portion 111 is formed by spin coating, and it is desirable to use a resin that can be coated by spin coating for the nozzle forming portion 111. From the viewpoint of chemical resistance, SU8, BCB, etc. are desirable. Then, as shown in FIG. 11, the nozzle 2 is formed by etching. The etching of the nozzle 2 is formed by dry etching.

[0038] Next, as shown in FIG. 12, the individual flow path substrate 100 is processed by Si etching to form a plurality of individual flow paths 4 in the shape of round holes. In this step, an individual flow path 4 is formed in which the cross-sectional area of the opening 4a of the individual flow path 4 is smaller than the cross-sectional area on the nozzle plate side. In the present embodiment, the individual flow path 4 is formed such that the inner diameter gradually increases from the opening 4a toward the nozzle plate side. Therefore, as shown in FIG. 12, in a cross-section parallel to the arrangement direction of the nozzles 2, the wall surface of the individual flow path has an inverted taper shape.

[0039] In order to form the individual flow path 4 having the shape shown in FIG. 12, in the present embodiment, processing is performed using a Bosch process which is a kind of dry etching. The Bosch process is a process that repeatedly performs a series of steps including an isotropic etching step, a protective film formation step, and a bottom protective film removal step by anisotropic etching. In the Bosch process, a vertical hole can be formed by proceeding with the processing while protecting the side walls with a protective film. The time of the isotropic etching step is made longer than the time of the previous isotropic etching step, and the processing width at the bottom is made larger than the previous processing width. As a result, as shown in FIG. 12, an individual flow path 4 is formed in which the inner diameter gradually increases from the opening 4a toward the nozzle plate side, and an individual flow path 4 is formed in which the cross-sectional area of the opening 4a is smaller than the cross-sectional area on the nozzle plate side.

[0040] Next, the verification experiment conducted by the present inventor will be described. Verification experiments were conducted to create the liquid ejection heads of Examples 1 to 8 and Comparative Examples 1 to 4 by changing the thickness of the individual flow path substrate 100, the inner diameter of the opening 4a of the individual flow path, and the inner diameter of the nozzle plate side of the individual flow path. Each example and each comparative example are as follows.

[0041] [Example 1] For the individual flow path substrate 100 with a thickness of 200 μm, the liquid ejection head of Example 1 with 1200 channels was created by the above-described manufacturing method. The outer diameter of the piezoelectric film 52 in the liquid ejection head of Example 1 was 144 μm, the nozzle diameter was 20 μm, the nozzle pitch was 12000 dpi, and the thickness of the column on the nozzle plate side between the four individual flow paths was 30 μm. Also, the width Wb (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the nozzle plate side of the individual flow path 4 was 180 μm, and the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the opening 4a of the individual flow path 4 was 124 μm. Wt / Wb = 0.689.

[0042] [Example 2] The liquid ejection head of Example 2 was the same as that of Example 1 except that the width wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the opening 4a was 179 μm. In this Example 2, Wt / Wb = 0.994.

[0043] [Example 3] The liquid ejection head of Example 3 was the same as that of Example 1 except that the thickness of the individual flow path substrate 100 was 700 μm, and Wt / Wb = 0.689.

[0044] [Example 4] The liquid ejection head of Example 4 was the same as that of Example 1 except that the width wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the opening 4a was 179 μm, and Wt / Wb = 0.994.

[0045] [Example 5] The liquid ejection head of Example 5 was the same as that of Example 1 except that the width Wb (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the nozzle plate side was 500 μm and the width Wt (inner diameter) of the opening 4a was 348 μm, and Wt / Wb = 0.696.

[0046] [Example 6] The liquid ejection head of Example 6 is the same as that of Example 5 except that the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the opening 4a is 498 μm, and Wt / Wb = 0.996.

[0047] [Example 7] The liquid ejection head of Example 7 is the same as that of Example 5 except that the thickness of the individual flow path substrate 100 is 700 μm, and Wt / Wb = 0.696.

[0048] [Example 8] The liquid ejection head of Example 8 is the same as that of Example 6 except that the thickness of the individual flow path substrate 100 is 700 μm, and Wt / Wb = 0.996.

[0049] [Comparative Example 1] The liquid ejection head of Comparative Example 1 is the same as that of Example 1 except that the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction of the opening 4a is 180 μm and Wt / Wb = 1.

[0050] [Comparative Example 2] The liquid ejection head of Comparative Example 2 is the same as that of Example 3 except that the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction is 180 μm and Wt / Wb = 1.

[0051] [Comparative Example 3] The liquid ejection head of Comparative Example 3 is the same as that of Example 5 except that the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction is 500 μm and Wt / Wb = 1.

[0052] [Comparative Example 4] The liquid ejection head of Comparative Example 4 is the same as that of Example 7 except that the width Wt (inner diameter) when viewed from the direction orthogonal to the liquid ejection direction is 500 μm and Wt / Wb = 1.

[0053] For the liquid ejection heads of the above Examples 1 to 8 and Comparative Examples 1 to 4, the influence of crosstalk was investigated. First, the ejection speed V of the liquid droplets ejected from the nozzle when only the piezoelectric element of the target channel was driven, and the ejection speed V' of the target channel when the target channel and other channels around the target channel were driven simultaneously were measured. The measurement of V' was performed for each of the cases where 100 channels around the target channel were driven simultaneously, 600 channels were driven simultaneously, and all 1200 channels were driven simultaneously. Then, the influence of crosstalk was investigated using the ejection speed V and the ejection speed V'.

[0054] When crosstalk occurs, the ejection efficiency decreases, so V' < V or (V' / V) < 1. In this verification experiment, if (V' / V)×100 ≧ 60%, since the influence on the image is small, it was judged as qualified. The verification results are shown in Table 1 below.

[0055]

Table 1

[0056] As can be seen from Table 1, in Comparative Examples 1 to 4 where the width Wt (inner diameter) of the opening 4a of the individual flow path and the width Wb (inner diameter) on the nozzle plate side of the individual flow path are the same (Wt / Wb = 1) and the cross-sectional area of the opening 4a and the cross-sectional area on the nozzle plate side are the same, the ratio of the ejection speed ((V' / V)×100%) at the time of simultaneous driving of 1200 channels was less than 60%, and they were judged as unqualified.

[0057] On the other hand, in Examples 1 to 8 where the width Wt (inner diameter) of the opening 4a of the individual flow path is less than the width Wb (inner diameter) on the nozzle plate side of the individual flow path ((Wt / Wb) < 1) and the cross-sectional area of the opening 4a is smaller than the cross-sectional area on the nozzle plate side, the ratio of the ejection speed ((V' / V)×100%) was 60% or more in all cases. Thus, it was confirmed that crosstalk can be suppressed by making the cross-sectional area of the opening 4a smaller than the cross-sectional area on the nozzle plate side.

[0058] In addition, in Examples 1, 3, 5, and 7 where (Wt / Wb) is approximately 0.70, for 100-channel simultaneous driving, 600-channel simultaneous driving, and 1200-channel simultaneous driving respectively, it was confirmed that the ratio of ejection speeds ((V' / V)×100%) was 90% or more, and crosstalk could be suppressed well.

[0059] Note that in all of Examples 1, 3, 5, and 7, (Wt / Wb) is approximately 0.70. This is because when (Wt / Wb) is less than approximately 0.70, in the formation of the individual flow path 4 by the above-described Bosch process, there are portions where the etching gas does not enter, resulting in etching defects. Therefore, if (Wt / Wb) is 0.70 or more, the individual flow path 4 can be formed well at least for a substrate thickness of 700 μm or less.

[0060] From the above verification experiments, in a liquid ejection head where the substrate thickness is 200 μm or more and 700 μm or less, and the width Wb (inner diameter) when viewed from a direction orthogonal to the liquid ejection direction on the nozzle plate side of the individual flow path is 180 μm to 500 μm, if at least (Wt / Wb) is 0.70 or more and 0.99 or less, ((V' / V)×100%) can be made 60% or more, and image disturbance due to crosstalk can be kept within an acceptable range.

[0061] Next, an example of an apparatus for ejecting a liquid according to the present invention will be described with reference to FIGS. 13 and 14. FIG. 13 is a schematic explanatory view of a printing apparatus which is an inkjet recording apparatus as an apparatus for ejecting a liquid in the present embodiment. FIG. 14 is a plan explanatory view of an example of a head unit of the printing apparatus of the present embodiment.

[0062] This printing apparatus 500 which is an apparatus for ejecting a liquid includes a loading means 501 for loading a continuous body 510, and a guiding and conveying means 503 for guiding and conveying the continuous body 510 loaded from the loading means 501 to a printing means 505. Further, the printing apparatus 500 also includes a printing means 505 for performing printing to form an image by ejecting a liquid onto the continuous body 510, a drying means 507 for drying the continuous body 510, an unloading means 509 for unloading the continuous body 510, and the like.

[0063] The continuous body 510 is sent out from the original winding roller 511 of the loading means 501, guided and conveyed by the rollers of the loading means 501, the guiding and conveying means 503, the drying means 507, and the unloading means 509, and wound up by the winding roller 591 of the unloading means 509. This continuous body 510 is conveyed on the conveyance guide member 559 facing the head unit 550 in the printing means 505, and an image is printed by the liquid discharged from the head unit 550.

[0064] In the printing apparatus 500 of the present embodiment, the head unit 550 is provided with the two head modules 100A and 100B according to the above-described present embodiment on the common base member 552.

[0065] When the arrangement direction of the liquid ejection heads 1 in the direction orthogonal to the conveyance direction of the head modules 100A and 100B is defined as the head arrangement direction, the same-color liquid is ejected from the head rows 1A1 and 1A2 of the head module 100A. Similarly, the head rows 1B1 and 1B2 of the head module 100A are taken as a set, the head rows 1C1 and 1C2 of the head module 100B are taken as a set, and the head rows 1D1 and 1D2 are taken as a set, and the liquid of the required color is ejected respectively.

[0066] Next, another example of the printing apparatus as the apparatus for ejecting the liquid according to the present invention will be described with reference to FIGS. 15 and 16. FIG. 15 is a plan explanatory view of the main part of the printing apparatus of this example. FIG. 16 is a side explanatory view of the main part of the printing apparatus of this example.

[0067] The printing apparatus 500 in this example is a serial type apparatus. By means of the main scanning movement mechanism 493, the carriage 403 reciprocates in the main scanning direction. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is bridged between the left and right side plates 491A and 491B and holds the carriage 403 movably. Then, by the main scanning motor 405, the carriage 403 is reciprocated in the main scanning direction via the timing belt 408 bridged between the driving pulley 406 and the driven pulley 407.

[0068] Mounted on this carriage 403 is a liquid discharge unit 440 which integrates the liquid discharge head 1 and the head tank 441 according to the present invention. The liquid discharge head 1 discharges liquids of respective colors such as yellow (Y), cyan (C), magenta (M), and black (K). Also, the liquid discharge head 1 arranges a nozzle row composed of a plurality of nozzles in the sub-scanning direction orthogonal to the main scanning direction and is mounted with the discharge direction facing downward. The liquid discharge head 1 is connected to a liquid circulation device, and the liquid of the required color is circulated and supplied.

[0069] This printing apparatus 500 is provided with a conveyance mechanism 495 for conveying the paper 410. The conveyance mechanism 495 includes a conveyance belt 412 which is a conveyance means, and a sub-scanning motor 416 for driving the conveyance belt 412. The conveyance belt 412 adsorbs the paper 410 and conveys it at a position facing the liquid discharge head 1. This conveyance belt 412 is an endless belt and is bridged between a conveyance roller 413 and a tension roller 414. The adsorption can be performed by electrostatic adsorption or air suction, etc. Then, the conveyance belt 412 circulates and moves in the sub-scanning direction when the conveyance roller 413 is rotationally driven by the sub-scanning motor 416 via the timing belt 417 and the timing pulley 418.

[0070] Further, on one side of the carriage 403 in the main scanning direction, a maintenance and recovery mechanism 420 for maintaining and recovering the liquid ejection head 1 is arranged on the side of the conveyance belt 412. The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 for capping the nozzle surface of the liquid ejection head 1, a wiper member 422 for wiping the nozzle surface, and the like. Further, the main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the conveyance mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0071] In the printing apparatus 500 configured as described above, the sheet 410 is fed onto the conveyance belt 412 and adsorbed, and the sheet 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 412. Therefore, by driving the liquid ejection head 1 in accordance with an image signal while moving the carriage 403 in the main scanning direction, liquid is ejected onto the stopped sheet 410 to form an image.

[0072] Next, another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 17. FIG. 17 is an explanatory plan view of a main part of the liquid ejection unit in this example.

[0073] This liquid ejection unit 440 is composed of a housing portion constituted by side plates 491A, 491B, and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection head 1 among the members constituting the apparatus for ejecting the liquid.

[0074] Note that a liquid ejection unit in which the above-described maintenance and recovery mechanism 420 is further attached to, for example, the side plate 491B of the liquid ejection unit 440 can also be configured.

[0075] Next, still another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 18. FIG. 18 is an explanatory front view of the liquid ejection unit in this example.

[0076] This liquid ejection unit 440 is composed of a liquid ejection head 1 to which a flow path component 444 is attached and a tube 456 connected to the flow path component 444.

[0077] Note that the flow path component 444 is disposed inside the cover 442. Instead of the flow path component 444, a head tank 441 can also be included. Further, a contact 443 for making an electrical connection with the liquid ejection head 1 is provided on the upper part of the flow path component 444.

[0078] In the present application, the liquid to be ejected only needs to have a viscosity and surface tension that can be ejected from the head, and is not particularly limited. However, it is preferably such that the viscosity becomes 30 mPa·s or less at normal temperature and normal pressure, or by heating or cooling. More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light emitting elements, liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0079] As an energy generation source for ejecting the liquid, those using piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements), thermal actuators using electrothermal conversion elements such as heating resistors, electrostatic actuators composed of a diaphragm and a counter electrode, etc. are included.

[0080] The "liquid ejection unit" is an integrated unit of functional parts and mechanisms in the liquid ejection head, and includes an aggregate of parts related to liquid ejection. For example, the "liquid ejection unit" includes those in which at least one of the configurations of a head tank, carriage, supply mechanism, maintenance and recovery mechanism, main scanning movement mechanism, and liquid circulation device is combined with the liquid ejection head.

[0081] Here, the term "integrated" includes, for example, cases where the liquid ejection head, functional components, and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., and cases where one is held movably with respect to the other. Also, the liquid ejection head, functional components, and mechanisms may be configured to be detachable from each other.

[0082] For example, as a liquid ejection unit, there is one in which a liquid ejection head and a head tank are integrated. Also, there is one in which a liquid ejection head and a head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter can also be added between the head tank and the liquid ejection head of these liquid ejection units.

[0083] Also, as a liquid ejection unit, there is one in which a liquid ejection head and a carriage are integrated.

[0084] Also, as a liquid ejection unit, there is one in which a liquid ejection head is movably held on a guide member that constitutes a part of a scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated. Also, there is one in which a liquid ejection head, a carriage, and a main scanning movement mechanism are integrated.

[0085] Also, as a liquid ejection unit, there is one in which a cap member that is a part of a maintenance and recovery mechanism is fixed to a carriage to which a liquid ejection head is attached, and the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated.

[0086] Also, as a liquid ejection unit, there is one in which a tube is connected to a liquid ejection head to which a head tank or a flow path component is attached, and the liquid ejection head and a supply mechanism are integrated. Through this tube, the liquid from a liquid storage source is supplied to the liquid ejection head.

[0087] The main scanning movement mechanism shall also include a single guide member. Also, the supply mechanism shall include a single tube and a single loading unit.

[0088] Here, the "liquid ejection unit" is described in combination with the liquid ejection head. However, the "liquid ejection unit" includes not only the head module or head unit that includes the above-described liquid ejection head, but also those in which the functional components and mechanisms as described above are integrated.

[0089] The "device for ejecting liquid" includes a liquid ejection head, a liquid ejection unit, a head module, a head unit, etc., and a device that drives the liquid ejection head to eject liquid. The device for ejecting liquid includes not only a device that can eject liquid onto an object to which liquid can adhere, but also a device that ejects liquid into the air or liquid.

[0090] This "device for ejecting liquid" can also include means related to the feeding, conveyance, and paper discharge of an object to which liquid can adhere, as well as other pre-treatment devices, post-treatment devices, etc.

[0091] For example, as the "device for ejecting liquid", there are an image forming device that ejects ink to form an image on paper, and a three-dimensional modeling device (three-dimensional forming device) that ejects a modeling liquid onto a powder layer formed in layers of powder in order to form a three-dimensional object (three-dimensional formed object).

[0092] In addition, the "device for ejecting liquid" is not limited to those in which a significant image such as characters or figures is visualized by the ejected liquid. For example, those that form a pattern or the like that has no meaning by itself, and those that create a three-dimensional image are also included.

[0093] The above-mentioned "object to which liquid can adhere" means an object to which liquid can adhere at least temporarily, such as an object that adheres and adheres firmly, or an object that adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording sheets, films, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as test cells, and all objects to which liquid adheres are included unless otherwise particularly limited.

[0094] The material of the above-mentioned "object to which liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere temporarily.

[0095] In addition, as the "device for discharging liquid", there is a device in which a liquid discharge head and an object to which liquid can adhere move relative to each other, but it is not limited thereto. Specific examples include a serial type device that moves the liquid discharge head and a line type device that does not move the liquid discharge head.

[0096] In addition, as the "device for discharging liquid", there is also a treatment liquid application device that discharges a treatment liquid onto paper in order to modify the surface of the paper for purposes such as modifying the surface of the paper. There is also an injection granulation device that injects a composition liquid in which raw materials are dispersed in a solution through a nozzle to granulate fine particles of the raw materials.

[0097] Note that in the terms of this application, image formation, recording, printing, imprinting, printing, shaping, etc. are all synonymous.

[0098] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims, unless otherwise specifically limited in the above description.

[0099] What has been described above is an example, and each of the following aspects has a specific effect. (Aspect 1) A liquid discharge head 1 including a plurality of nozzles 2 for discharging liquid, a plurality of individual flow paths 4 communicating with the plurality of nozzles 2 respectively, and actuators such as a plurality of piezoelectric elements 5 provided on the nozzle forming walls of the plurality of individual flow paths 4, and driving the actuators to discharge the liquid in the individual flow paths from the nozzles 2, wherein the cross-sectional area of a liquid introduction part such as an opening 4a located on the side facing the nozzle forming wall of the individual flow path 4 and into which liquid is introduced from the common flow path 3 is smaller than the cross-sectional area of the nozzle forming wall side of the individual flow path 4. According to this, as described in the embodiment, by making the cross-sectional area of the liquid introduction portion into which the liquid is introduced from the common flow path smaller than the cross-sectional area on the nozzle formation wall side of the individual flow path, the flow path resistance of the liquid introduction portion can be increased compared to the case where the cross-sectional area of the liquid introduction portion is the same as the cross-sectional area on the nozzle formation wall side of the individual flow path, and the flow rate of the liquid passing through the liquid introduction portion can be decreased. As a result, it is possible to suppress the liquid flowing in the direction away from the nozzle from flowing back to the common flow path through the liquid introduction portion due to the vibration in the liquid ejection direction of the actuator. Thereby, fluid crosstalk can be suppressed.

[0100] (Aspect 2) In Aspect 1, when the width on the nozzle formation wall side, which is the nozzle plate 110 side of the individual flow path 4, is Wb and the width of the liquid introduction portion such as the opening 4a is Wt when viewed from the direction orthogonal to the liquid ejection direction, 0.7 ≦ Wt / Wb < 0.99. According to this, as described in the verification experiment, it is possible to suppress the decrease in the ejection efficiency due to crosstalk compared to Comparative Examples 1 to 4 where Wt / Wb = 1.

[0101] (Aspect 3) In Aspect 2, the width Wb on the nozzle formation wall side is 180 μm or more and 500 μm or less. According to this, as described in the verification experiment, at least when the width Wb on the nozzle formation wall side is within the range of 180 μm or more and 500 μm or less, it is possible to suppress the decrease in the ejection efficiency due to crosstalk.

[0102] (Aspect 4) In Aspect 2 or 3, the thickness of the individual flow path substrate 100 in which a plurality of individual flow paths 4 are formed is 200 μm or more and 700 μm or less. According to this, as described in the verification experiment, at least when the thickness of the flow path substrate is within the range of 200 μm or more and 700 μm or less, it is possible to suppress the decrease in the ejection efficiency due to crosstalk.

[0103] (Aspect 5) In any one of Aspects 1 to 4, the cross-sectional area of the liquid introduction part such as the opening 4a is smaller than the cross-sectional area of the vibrating part of the diaphragm 103 on the nozzle forming wall side. According to this, as described in the embodiment, compared with the case where the cross-sectional area of the liquid introduction part such as the opening 4a is the same as the cross-sectional area of the vibrating part of the diaphragm 103 of the individual flow path 4, the flow path resistance of the liquid introduction part can be increased, and the flow rate of the liquid passing through the liquid introduction part can be decreased. Thereby, it is possible to suppress the liquid flowing in the direction away from the nozzle from flowing back to the common flow path through the liquid introduction part due to the vibration of the actuator in the liquid discharge direction. Thereby, fluid crosstalk can be suppressed.

[0104] (Aspect 6) In any one of Aspects 1 to 5, the cross-sectional area of the liquid introduction part such as the opening 4a is smaller than the cross-sectional area of the actuator such as the piezoelectric element 5. According to this, as described in the embodiment, compared with the case where the cross-sectional area of the liquid introduction part such as the opening 4a is the same as the cross-sectional area of the vibrating part of the actuator such as the piezoelectric element 5, the flow path resistance of the liquid introduction part can be increased, and the flow rate of the liquid passing through the liquid introduction part can be decreased. Thereby, it is possible to suppress the liquid flowing in the direction away from the nozzle from flowing back to the common flow path through the liquid introduction part due to the vibration of the actuator in the liquid discharge direction. Thereby, fluid crosstalk can be suppressed.

[0105] (Aspect 7) In any one of Aspects 1 to 6, the plurality of individual flow paths 4 are formed by a Bosch process. According to this, as described in the embodiment, it is possible to easily form the individual flow path 4 in which the cross-sectional area of the liquid introduction part such as the opening 4a is smaller than the cross-sectional area on the nozzle forming wall side.

[0106] (Aspect 8) In Aspect 7, the individual flow path substrate 100 in which the plurality of individual flow paths 4 are formed has a drive circuit such as CMOS 101 for applying a voltage to an actuator such as the piezoelectric element 5. According to this, as described in the embodiment, it is not necessary to mount a separate substrate having a drive circuit. As a result, the area of the external connection portion can be reduced, and the head can be miniaturized.

[0107] (Aspect 9) In Aspect 8, an actuator such as the piezoelectric element 5 is formed at a temperature of 450°C or lower. According to this, as described in the embodiment, it is possible to prevent the drive circuit of the flow path substrate from being damaged by the heat during the film formation of the actuator such as the piezoelectric element 5.

[0108] (Aspect 10) In Aspect 9, an actuator such as the piezoelectric element 5 is formed by sputtering. According to this, as described in the embodiment, compared with the case of forming a film by the sol-gel method, the film formation temperature can be suppressed, and it is possible to prevent the drive circuit of the flow path substrate from being damaged by the heat during the film formation.

[0109] (Aspect 11) In a device that discharges a liquid, a liquid discharge head according to any one of Aspects 1 to 10 is provided. According to this, the liquid can be discharged favorably.

Explanation of Signs

[0110] 1: Liquid discharge head 2: Nozzle 3: Common flow path 4: Individual flow path 4a: Opening 5: Piezoelectric element 6: Electrical connection pad 7a: First contact 7b: Second contact 7c: Third contact 7d: Fourth contact 7e: Fifth contact 8a: First insulating film 8b: Second insulating film 9a: First lead wiring 9b: Second extraction wiring 51: First electrode 52: Piezoelectric film 53: Second electrode 100: Individual flow path substrate 100a: Active layer 100b: BOX layer 101: CMOS 102: Wiring layer 103: Vibration film 110: Nozzle plate 111: Nozzle forming part 120: Common flow path substrate 151: First electrode layer 152: Piezoelectric layer 153: Second electrode layer

Prior art documents

Patent documents

[0111]

Patent Document 1

Claims

1. A plurality of nozzles for discharging a liquid, A plurality of individual flow paths respectively communicating with the plurality of nozzles, A plurality of actuators respectively provided on each nozzle forming wall of the plurality of individual flow paths, and a liquid discharge head for driving the actuators to discharge the liquid in the individual flow paths from the nozzles, A liquid discharge head, wherein a cross-sectional area of a liquid introduction portion located on a side facing a nozzle forming wall of the individual flow path and into which liquid is introduced from a common flow path is smaller than a cross-sectional area on a nozzle forming wall side of the individual flow path.

2. The liquid discharge head according to claim 1, When a width of the nozzle forming wall side of the individual flow path is Wb and a width of the liquid introduction portion is Wt as viewed from a direction orthogonal to a liquid discharge direction, 0.7 ≦ Wt / Wb < 0.99 The liquid discharge head is characterized by the above.

3. The liquid discharge head according to claim 2, The liquid discharge head is characterized in that a width Wb on the nozzle forming wall side is 180 μm or more and 500 μm or less.

4. The liquid discharge head according to claim 2, The liquid discharge head is characterized in that a thickness of a flow path substrate on which the plurality of individual flow paths are formed is 200 μm or more and 700 μm or less.

5. The liquid discharge head according to claim 1, The liquid discharge head is characterized in that a cross-sectional area of the liquid introduction portion is smaller than a cross-sectional area of a vibrating portion of a diaphragm on a nozzle forming wall side.

6. The liquid discharge head according to claim 1, The liquid discharge head is characterized in that a cross-sectional area of the liquid introduction portion is smaller than a cross-sectional area of the actuator.

7. The liquid discharge head according to claim 1, The liquid discharge head is characterized in that the plurality of individual flow paths are formed by a Bosch process.

8. The liquid discharge head according to claim 7, The liquid discharge head is characterized in that a flow path substrate on which the plurality of individual flow paths are formed has a drive circuit for applying a voltage to the actuator.

9. The liquid discharge head according to claim 8, The liquid discharge head is characterized in that the actuator is formed into a film at a temperature of 450 °C or lower.

10. The liquid discharge head according to claim 9, The liquid discharge head is characterized in that the actuator is formed into a film by sputtering.

11. An apparatus for discharging a liquid, comprising the liquid discharge head according to claim 1.

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