Liquid discharge head and liquid discharging device

Abstract

To provide a liquid discharge head and a liquid discharging device that can discharge also a material with high melt temperature, can achieve reduction of consumption power, and can achieve down-sizing of a device.SOLUTION: A liquid discharge head 1 comprises a nozzle plate 110, and a pressure chamber substrate 100. The nozzle plate 110 is a thin film-like, and has: a plurality bof nozzles 2 for discharging liquid; a piezoelectric element 5 as an annular electromechanical conversion element located around the nozzles 2; and a heating heater 20. The pressure chamber substrate 100 has a plurality of pressure chambers 4 which communicate with the plurality of nozzles 2 respectively. The piezoelectric element 5 comprises a first electrode layer 151, a piezoelectric layer 152 being a piezoelectric material, and a second electrode layer 153, and the piezoelectric layer 152 is made of AlN (aluminum nitride).SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, a liquid ejection head that drives a piezoelectric body to eject a liquid from a nozzle has been known.

[0003] Patent Document 1 describes a liquid ejection head that ejects molten solder from a nozzle to form solder bumps on a semiconductor chip or the like. A piezoelectric body is provided on a counter wall facing the nozzle forming wall of the pressure chamber, and the molten solder is ejected from the nozzle by vibrating the counter wall. Further, a heater is provided on a cover member that covers the liquid ejection head, and the solder inside the liquid ejection head is heated to a temperature equal to or higher than the melting temperature.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, there is a possibility that the ejectable material is limited. Further, as the heater, it is necessary to use a heater having a large heater capacity, and there is a possibility that the apparatus becomes large-sized.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention is a liquid ejection head that drives a piezoelectric body to eject a liquid from a nozzle, wherein the piezoelectric body and a heating heater are provided on a nozzle forming wall of a pressure chamber communicating with the nozzle.

Effects of the Invention

[0006] According to the present invention, it is possible to eject a material having a high melting temperature, and it is possible to reduce the size of the apparatus.

Brief Description of the Drawings

[0007]

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MODE FOR CARRYING OUT THE INVENTION

[0008] The best mode for carrying out the present invention will be described below 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] FIG. 1 is a perspective view schematically showing the nozzle surface of the liquid ejection head of the present embodiment, and FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1.

[0010] The liquid ejection head 1 includes a nozzle plate 110 and a pressure chamber substrate 100. The nozzle plate 110 is in a thin film shape and has a plurality of nozzles 2 for ejecting liquid, a piezoelectric element 5 as an annular electromechanical conversion element disposed around the nozzles 2, and a heater 20.

[0011] The pressure chamber substrate 100 has a plurality of pressure chambers (also referred to as individual liquid chambers and pressurized liquid chambers) 4 that communicate with the plurality of nozzles 2 respectively. There is a nozzle 2 (vibration film 103) on one surface of the pressure chamber 4, and an opening 4a of the pressure chamber is disposed on the side facing the one surface. The nozzle plate 110 and the pressure chamber substrate 100 are formed and processed by semiconductor manufacturing technology, and the pressure chambers 4, nozzles 2, piezoelectric elements 5, and heaters 20 are densely mounted at the semiconductor wafer level.

[0012] The pressure chamber substrate 100 is an SOI (Silicon on Insulator) substrate and has a drive circuit and a wiring layer 102 on the side where the vibration film 103 is formed. The drive circuit is a circuit including transistors, resistors, and the like. The wiring layer 102 has a wiring portion for applying a drive waveform to the first electrode 51 and a wiring portion for applying a drive waveform to the second electrode 53. Further, the wiring layer 102 is also provided with a wiring portion for applying a voltage to the heat generating portion 21 of the heater 20 and a wiring portion for applying a voltage to the temperature sensing portion 22 for sensing the temperature of the heater 20.

[0013] By integrating the drive circuit into the pressure chamber substrate 100, the implementation process of the drive circuit using a separate substrate can be reduced, and the area of the external connection part can also be reduced, leading to the miniaturization of the head. If the drive circuit is not built into the pressure chamber substrate 100 and an opening is provided in the nozzle plate 110 for external drive control, the pressure chamber 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. When the liquid ejection continues, the mist generated simultaneously with the ejection adheres to the nozzle surface. If a large amount of this mist adheres to the nozzle surface, the liquid ejected from the nozzle 2 may be displaced from the desired landing position under the influence of the liquid adhering to the nozzle surface. By forming a liquid-repellent film on the nozzle surface, the adhesion of the liquid to the nozzle surface can be suppressed, and the influence of the liquid adhering to the nozzle surface on the liquid ejected from the nozzle 2 can be suppressed.

[0015] The piezoelectric element 5 of the nozzle plate 110 has a first electrode 51 (also referred to as the lower electrode), a piezoelectric body 52, and a second electrode 53 (also referred to as the 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 third contact 7c for making an electrical connection to the first electrode 51 and a hole-shaped fourth contact 7d for making an electrical connection to the second electrode 53.

[0016] Also, on the first insulating film 8a, a first lead wiring 9a for electrically connecting the first electrode 51 of the piezoelectric element 5 and the wiring layer 102 of the pressure chamber substrate 100, and a second lead wiring 9b for electrically connecting the second electrode 53 of the piezoelectric element 5 and the wiring layer 102 of the pressure chamber substrate 100 are formed.

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

[0018] Note that lead wiring portions may be provided on the first electrode 51 and the second electrode 53, respectively, and they may be directly and electrically connected to the wiring layer 102 through contacts formed in the diaphragm. 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 heater 20 is disposed between the diaphragm 103 and the piezoelectric element 5 and includes a heating portion 21, a temperature sensing portion 22, and an insulating film 23. Examples of the material of the heating portion 21 include molybdenum and platinum. By using molybdenum or platinum as the heating portion 21, efficient heating due to high resistivity can be performed.

[0020] The outer end portion of the heating portion 21 (the position farthest from the nozzle) is located substantially at the same position as the outer end portion of the first electrode 51 having the largest area of the piezoelectric element 5. The heating area of the heater 20 is the maximum area of the piezoelectric element 5 (= the area of the first electrode) and corresponds to the cross-sectional area perpendicular to the liquid ejection direction of the pressure chamber 4. Thereby, the liquid in the pressure chamber 4 can be heated evenly.

[0021] Also, by using platinum as the material of the heating part 21, the material of the temperature sensing part 22 can be platinum, and they can be formed simultaneously on the same surface. As the temperature sensing part 22, by using platinum, temperature detection can be performed by utilizing the positive temperature coefficient of platinum. Thereby, based on the temperature detected by the temperature sensing part 22, the heating heater 20 can be feedback-controlled, and precise temperature control can be realized. The thickness of the heating heater 20 is 1 μm and it is formed by a thin film forming process.

[0022] In the liquid ejection head of this embodiment, a metal material such as solder, a material that is solid at normal temperature such as wax ink, or a liquid with high viscosity at normal temperature such as UV ink is used as the ejection material ejected from the nozzle. Specifically, the ejection material that is solid at normal temperature is heated to a temperature equal to or higher than the melting temperature, and the liquid with high viscosity at normal temperature is heated to a temperature equal to or higher than the temperature at which the viscosity becomes a predetermined viscosity or lower and then ejected from the nozzle 2. As described above, by providing the heating heater 20 on the nozzle plate 110, the ejection material in the pressure chamber 4 can be made into a molten state or a state with low viscosity, and the liquid can be ejected from the nozzle well. Also, since the nozzle plate 110 can be heated, it is possible to suppress the solidification of the liquid adhering to the nozzle surface.

[0023] Note that a heating heater 20 may also be provided on the partition wall that partitions the pressure chamber 4 of the pressure chamber substrate 100. Thereby, compared with the configuration in which the heating heater is provided only on the nozzle plate 110, the ejection material in the pressure chamber can be preferably maintained at a temperature equal to or higher than the melting temperature or a temperature equal to or higher than the temperature at which the viscosity becomes a predetermined viscosity or lower.

[0024] FIG. 3 is a diagram showing an example of the patterning of the heating part 21 of the heating heater 20. In this embodiment, in FIG. 3(a), the heating part 21 is patterned in a spiral shape. However, as shown in FIG. 3(b), the entire area corresponding to the pressure chamber 4 of the heater 20 may be used as the heating part. In the configuration shown in FIG. 3(a), the heating efficiency is inferior to that of the configuration shown in FIG. 3(b). However, compared with FIG. 3(b), the thickness of the diaphragm can be partially reduced, and the displacement amount of the diaphragm can be increased. On the other hand, as shown in FIG. 3(b), by using the entire area corresponding to the pressure chamber 4 of the heater 20 as the heating part, the heating efficiency can be improved compared with the spiral patterning of FIG. 3(a). As shown in FIGS. 3(a) and 3(b), the temperature sensing part 22 is provided on the nozzle side of the heating part 21 and is patterned in a ring shape.

[0025] Also, a configuration may be adopted in which a plurality of annular heating parts 21 are provided concentrically. Further, these plurality of heating parts may be controlled individually. For example, only the heating part 21 near the nozzle 2 may be heated during head cleaning so that the liquid adhered near the nozzle can be melted and removed.

[0026] FIG. 4 is a diagram showing an example of the sequence of temperature control of the heater 20. As shown in FIG. 4, an output value (current value) corresponding to the temperature of the liquid in the pressure chamber 4 (nozzle 2), which is the control target, by the temperature sensing part 22 is input to the input part 25c of the temperature adjustment part 25 as an observed value. Based on the observed value of the temperature sensing part 22 input to the input part 25c, the temperature of the liquid in the pressure chamber 4 (nozzle 2) is detected, and the detected temperature is compared with the target temperature by the comparison part 25d. Then, the difference value between the target temperature and the detected temperature is calculated by the comparison part 25d, and the difference value is output to the adjustment part 25a. The adjustment part 25a sets the power value input to the heating part 21 as an operation part as an operation amount by PID control. Then, the set power value as the operation amount is input to the heating part 21, and the liquid in the pressure chamber 4, which is the control target, is controlled to a desired temperature.

[0027] The piezoelectric body 52 is heated by a heater 20 or the like and its temperature rises. When the ejection material is a metal material such as solder, it is necessary to maintain the liquid in the pressure chamber at a temperature of 220°C or higher with the heater 20. Therefore, the temperature of the heating section 21 of the heater 20 becomes 300°C or higher. As a result, the piezoelectric body 52 of the nozzle plate 110 is exposed to a high temperature of at least 220°C or higher.

[0028] As the electrostrictive material of the piezoelectric body of the inkjet head, PZT (lead zirconate titanate) is widely used because of its high piezoelectric characteristics. PZT is a ferroelectric material and has electric dipoles in which the substance is locally divided into positively charged and negatively charged parts even without applying an external electric field. However, in ferroelectric materials such as PZT, depolarization occurs at a high temperature of 200°C or higher, resulting in the loss of piezoelectricity and displacement.

[0029] Therefore, in this embodiment, AlN (aluminum nitride) is used as the electrostrictive material of the piezoelectric body 52. Since the displacement amount of AlN does not change even at a high temperature, it can be driven well even when exposed to a high temperature of 220°C or higher.

[0030] Also, in this embodiment, a nozzle vibration method is adopted in which the piezoelectric element 5 is arranged on the nozzle plate 110, and the pressure in the pressure chamber 4 is varied by the piezoelectric element 5 of the nozzle plate 110 to eject the liquid in the pressure chamber from the nozzle. The nozzle vibration method has the characteristic that droplets can be ejected with a smaller force compared to a general unimorph type piezo head (which vibrates the surface facing the wall portion (nozzle communication wall) having a communication port communicating with the nozzle of the pressure chamber to eject the liquid). Therefore, even if AlN with a displacement amount lower than that of PZT is used as the electrostrictive material of the piezoelectric body 52, the liquid can be ejected well.

[0031] As a result, even for an ejection material with a high melting temperature such as solder, it can be melted and ejected. Also, by using AlN with high heat resistance, a configuration such as heat-insulating the piezoelectric body 52 with a heat-insulating material is not required so that the piezoelectric body 52 does not become hot due to the heater 20 or the melted ejection material, and the device can be miniaturized.

[0032] Also, by using AlN with high heat resistance whose displacement amount does not change even at high temperatures as the material of the piezoelectric body 52, the heating heater 20 can be provided on the nozzle plate 110. Thereby, the discharge material in the pressure chamber 4 can be efficiently heated, and the discharge material in the pressure chamber can be maintained at a temperature equal to or higher than the melting temperature with a small heater capacity. Thereby, reduction of power consumption can be achieved. Also, miniaturization of the heater can be achieved, and enlargement of the apparatus can be suppressed.

[0033] Furthermore, the nozzle plate 110 and the pressure chamber substrate 100 are formed and processed by semiconductor manufacturing technology, and the pressure chamber 4, the nozzle 2, the piezoelectric element 5, and the heating heater 20 are mounted in a thin film shape with high density at the semiconductor wafer level. Thereby, miniaturization of the liquid discharge head can be achieved, and the heat capacity of the liquid discharge head can be reduced. Therefore, the discharge material in the pressure chamber 4 can be heated more efficiently.

[0034] Also, by using AlN as the electrostrictive material, the following advantages can also be obtained. That is, although the piezoelectric characteristics can be improved by aligning the crystal orientation of the piezoelectric body 52, an orientation control layer may be provided between the diaphragm 103 and the first electrode 51 for the orientation control. When the material of the piezoelectric body 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 body 52 is aligned, and improvement of the piezoelectric characteristics becomes possible.

[0035] In addition, as the electrostrictive material of the piezoelectric body, aluminum nitride (AlN) containing at least one material of scandium, yttrium, titanium, magnesium, hafnium, zirconium, tin, chromium, and boron may be used. Specifically, a part of aluminum in aluminum nitride is replaced with at least one of the above materials. Thereby, at least one of the above materials can be included in aluminum nitride. As the piezoelectric material, by replacing a part of aluminum in aluminum nitride with at least one of the above materials, the piezoelectric performance can be enhanced. Further, as the electrostrictive material of the piezoelectric body 52, it is not limited to aluminum nitride, and any electrostrictive material with high heat resistance whose displacement amount does not change even in a high-temperature environment may be used.

[0036] FIG. 5 is a diagram showing a modified example of the liquid ejection head. In the liquid ejection head of this modified example, the nozzle plate 110 is arranged in the order of the vibration film 103, the piezoelectric element 5, and the heating heater 20 from the pressure chamber 4 side. In this modified example, since the piezoelectric element 5 is formed on the vibration film 103, the vibration film 103 can be vibrated well, and the displacement amount of the vibration film 103 can be increased.

[0037] On the other hand, since the liquid ejection head shown in FIG. 2 is on the pressure chamber 4 side rather than the liquid ejection head of the modified example, the ejection material in the pressure chamber 4 can be efficiently heated. Thereby, the calorific value of the heating part 21 can be suppressed, and the ejection material in the pressure chamber 4 can be maintained at a temperature equal to or higher than the melting temperature or a temperature equal to or higher than a predetermined viscosity or lower, and power consumption can be reduced.

[0038] Further, the vibration film 103, the inner heating heater, the piezoelectric element 5, and the outer heating heater may be arranged in this order from the pressure chamber 4 side, and a plurality of heating heaters may be provided on the nozzle plate. Regarding the outer heating heater, a heating part is provided only on the nozzle vicinity side, and the vicinity of the nozzle is heated by the outer heating heater during head cleaning to melt and remove the liquid adhered to the vicinity of the nozzle.

[0039] Next, the manufacturing method of the liquid ejection head of the present embodiment will be described. The liquid ejection head of this embodiment realizes low-cost and high-density mounting by forming the pressure chamber 4, nozzle 2, piezoelectric element 5, and heater 20 through a semiconductor manufacturing process. Figs. 6 to 15 are cross-sectional views showing a cross-section orthogonal to the arrangement direction of nozzle holes for explaining the manufacturing process of the liquid ejection head of this embodiment manufactured by a semiconductor manufacturing process.

[0040] First, as shown in Fig. 6, a drive circuit and wiring layer 102 including transistors, resistors, etc. are formed on the silicon film of the pressure chamber substrate 100 as an SOI (Silicon on Insulator) substrate. The wiring layer 102 is formed by a damascene method or the like. SiO2 is deposited and patterned to form grooves, and the grooves are filled with wiring metal. The above is covered with SiO2. The above steps are repeated. Specifically, it is planarized by CMP polishing, and the deposition and patterning of SiO2 are repeated again. Thereby, a three-dimensional fine wiring can be constructed. As a result, a wiring portion for applying a drive waveform to the first electrode 51 and a wiring portion for applying a drive waveform to the second electrode 53 are formed. Also, a wiring portion for applying a voltage to the heat generating portion 21 of the heater 20 and a wiring portion for applying a voltage to the temperature sensing portion 22 for sensing the temperature of the heater 20 are formed.

[0041] Next, a diaphragm 103 is formed on the surface of the pressure chamber substrate 100 where the wiring layer is formed. The material of the diaphragm 103 may be at least an insulating material 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. Considering the difference in the linear expansion coefficient from the pressure chamber substrate 100, SiO2 with a relatively small difference is most desirable as the material of the diaphragm 103.

[0042] Next, as shown in Fig. 7, a heater 20 is formed on the diaphragm 103. The heat generating part 21 and the temperature sensing part 22 of the heating heater 20 form a platinum film on the diaphragm 103 using a sputtering method, and are processed by photolithography and etching to form the heat generating part 21 and the temperature sensing part 22 of a desired pattern. Then, by forming the insulating film 23, the heating heater 20 is formed. Also, similar to the wiring layer 102 described above, the heating heater 20 may be formed by a damascene method. Specifically, SiO2 is formed and patterned to create a groove, the groove is filled with platinum, and the top is covered with SiO2, thereby forming the heating heater 20 on the diaphragm 103.

[0043] Next, as shown in FIG. 8, a first electrode layer 151, a piezoelectric layer 152, and a second electrode layer 153 are formed on the heating heater 20. 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.

[0044] By using AlN as the piezoelectric material constituting the piezoelectric layer 152, the film formation temperature can be set to 450 °C or lower. When a drive circuit (CMOS circuit) is provided in a part corresponding to the wiring layer 102, it is possible to suppress the thermal destruction of transistors, resistors, etc. constituting the drive circuit.

[0045] 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 the drive circuit and the wiring part are incorporated in the pressure chamber substrate 100, it is desirable to use the sputtering method for film formation.

[0046] After depositing the first electrode layer 151, the piezoelectric layer 152, and the second electrode layer 153, as shown in FIG. 9, they are shaped into a suitable form to obtain a piezoelectric element 5 composed of the first electrode 51, the piezoelectric body 52, and the second electrode 53. By processing the first electrode layer 151, the piezoelectric layer 152, and the second electrode layer 153 through photolithography and etching, the first electrode 51, the piezoelectric body 52, and the second electrode 53 with 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 body 52. Since residues are likely to remain after dry etching, a cleaning process may be added after shaping to remove the residues.

[0047] After forming the first electrode 51, the piezoelectric body 52, and the second electrode 53, as shown in FIG. 10, the first insulating film 8a is deposited. The first insulating film 8a has insulation properties similar to those of the diaphragm 103, preferably has a small Young's modulus, and a linear expansion coefficient close to that of the constituent materials. Therefore, it is preferable to use the same SiO2 as that of the diaphragm 103. Also, a very thin metal oxide may be used as the material of the first insulating film 8a to improve reliability.

[0048] After forming the first insulating film 8a, as shown in FIG. 10, via holes 7c and 7d in the shape of holes are formed in the first insulating film 8a through photolithography and etching. Also, via holes 7c and 7d in the shape of holes that penetrate the insulating film 23 of the diaphragm 103 and the heating heater 20 are formed.

[0049] Next, as shown in FIG. 11, the first lead wiring 9a and the second lead wiring 9b are formed. The materials of the respective lead wirings 9a, 9b are generally Al or an AlCu alloy, but noble metals can also be used to improve reliability. Through this process, the first lead wiring 9a is electrically connected to the first electrode 51 via the third contact 7c and is electrically connected to the wiring layer 102 via the first contact 7a. Also, the second lead wiring 9b is electrically connected to the second electrode 53 via the fourth contact 7d and is electrically connected to the wiring layer 102 via the second contact 7b.

[0050] Next, as shown in FIG. 12, a second insulating film 8b is formed so as to cover each lead wire 9a, 9b and the piezoelectric element 5. The second insulating film 8b may also be made of SiO2 as in the case of the first insulating film 8a, but in order to improve the reliability against humidity, it is desirable to use SiN having moisture resistance, which is widely used as a protective film for semiconductors. By having two functions of insulation and moisture resistance as the second insulating film 8b, the nozzle plate 110 can be made thinner than the case where a moisture-resistant protective film is formed on the second insulating film 8b. In the above steps, the piezoelectric element 5 can be driven.

[0051] Next, as shown in FIG. 13, 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 applied 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. 14, the nozzle 2 is formed by etching. The etching of the nozzle 2 is formed by dry etching. Next, as shown in FIG. 15, the pressure chamber substrate 100 is processed by Si etching to form a plurality of pressure chambers 4 in a round hole shape, thereby forming a liquid ejection head.

[0052] Next, an example of an apparatus for ejecting a liquid according to the present invention will be described. FIG. 16 is a schematic configuration diagram of a printing apparatus 300 as an apparatus for ejecting a liquid. As shown in FIG. 16, the printing apparatus 300 includes a liquid ejection unit 301 having a liquid ejection head 1 and a supply device 302, and a table 320 on which a substrate 310 is installed.

[0053] The liquid ejection head 1 has a common liquid chamber 3 which is a supply liquid chamber that supplies molten solder, which is a molten metal, to each pressure chamber 4. A heating heater 3a is provided on the wall of the common liquid chamber 3. The supply device 302 has a pellet loading portion 302a on which solder pellets are loaded. Solder pellets are supplied from this pellet loading portion 302a to the common liquid chamber 3. The solder pellets supplied to the common liquid chamber 3 are heated by the heating heater 3a as a second heating heater and become molten. Note that a heating heater may be provided in the supply device to supply molten solder to the common liquid chamber 3.

[0054] The liquid ejection unit 301 is configured to be movable in the left - right direction (hereinafter referred to as the sub - scanning direction) and the direction orthogonal to the paper surface (hereinafter referred to as the main scanning direction) in the figure. Then, while moving this liquid ejection unit in the main scanning direction and the sub - scanning direction, molten solder is ejected from the nozzle 2 to form solder bumps at desired positions on the substrate 310 on the table 320.

[0055] Note that the liquid ejection unit 301 may be configured to be able to eject liquid from one end to the other end in the main scanning direction, the liquid ejection unit 301 may be fixed, and the substrate 310 may be conveyed in the sub - scanning direction by a conveying device to form solder bumps at desired positions on the substrate 310. In the above printing device, although solder is used as the ejection material, solid ink such as wax ink can be used as the ejection material.

[0056] Next, another example of the printing device as a device for ejecting a liquid according to the present invention will be described with reference to FIGS. 17 and 18. FIG. 17 is a plan explanatory view of a main part of the printing device of this example. FIG. 18 is a side explanatory view of a main part of the printing device of this example.

[0057] The printing apparatus 500 in this example is a serial type apparatus. By 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, and the like. The guide member 401 is spanned 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 spanned between the driving pulley 406 and the driven pulley 407.

[0058] On this carriage 403, a liquid discharge unit 440 integrating the liquid discharge head 1 and the head tank 441 according to the present invention is mounted. The liquid discharge head 1 discharges liquids of respective colors such as yellow (Y), cyan (C), magenta (M), and black (K). Further, 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.

[0059] This printing apparatus 500 includes 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 spanned 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 is circulated in the sub-scanning direction by the conveyance roller 413 being rotationally driven via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

[0060] 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.

[0061] 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.

[0062] Next, another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 19. FIG. 19 is a plan explanatory view of a main part of the liquid ejection unit of this example.

[0063] This liquid ejection unit 440 is composed of a housing portion formed 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.

[0064] 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.

[0065] Next, still another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 20. FIG. 20 is a front explanatory view of the liquid ejection unit of this example.

[0066] 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.

[0067] 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 connector 443 for making an electrical connection with the liquid ejection head 1 is provided above the flow path component 444.

[0068] In such a printing apparatus 500, by using the liquid ejection head of the present invention, as the ejection material, it is possible to use an ink whose viscosity decreases by heating, such as UV ink, or an ink that is used by heat-melting a solid ink or the like.

[0069] Also, the liquid ejection head of the present invention can be applied to a printing apparatus that uses a metal ink containing metal nanoparticles to print a wiring pattern on a substrate. By heating and ejecting the metal ink using the liquid ejection head of the present invention, the solvent of the metal ink can be evaporated from the moment it is ejected onto the substrate, suppressing the wet spreading of the metal ink on the substrate and making it possible to form a fine wiring pattern.

[0070] As described above, the preferred embodiments of the present invention have been explained, but 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 as long as it is not particularly limited in the above description.

[0071] 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, but it is preferably at least one whose viscosity becomes 30 mPa·s or less by heating. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional additive materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, edible materials such as natural pigments, etc. Solutions, suspensions, emulsions, molten metals such as solder, etc. containing these can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic devices and light-emitting devices, liquids for forming electronic circuit resist patterns, liquids for forming solder bumps, and material liquids for three-dimensional modeling.

[0072] The "liquid ejection unit" is an integrated unit of functional components and mechanisms in a liquid ejection head, and includes an aggregate of components related to liquid ejection. For example, the "liquid ejection unit" includes at least one of the configurations of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, a main scanning movement mechanism, and a liquid circulation device combined with a liquid ejection head.

[0073] Here, the integration includes, for example, those in which the liquid ejection head and functional components and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., and those in which one is movably held with respect to the other. Also, the liquid ejection head and functional components and mechanisms may be configured to be detachable from each other.

[0074] 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.

[0075] Also, as a liquid ejection unit, there is one in which a liquid ejection head and a carriage are integrated.

[0076] In addition, as a liquid discharge unit, there is one in which a liquid discharge head is movably held by a guide member that forms part of a scanning movement mechanism, and the liquid discharge head and the scanning movement mechanism are integrated. Also, there is one in which the liquid discharge head, the carriage, and the main scanning movement mechanism are integrated.

[0077] In addition, as a liquid discharge unit, there is one in which a cap member that is part of a maintenance and recovery mechanism is fixed to a carriage to which a liquid discharge head is attached, and the liquid discharge head, the carriage, and the maintenance and recovery mechanism are integrated.

[0078] In addition, as a liquid discharge unit, there is one in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and the supply mechanism are integrated. Through this tube, the liquid from the liquid storage source is supplied to the liquid discharge head.

[0079] The main scanning movement mechanism shall include a single guide member. Also, the supply mechanism shall include a single tube and a single loading unit.

[0080] Here, the "liquid discharge unit" is described in combination with the liquid discharge head. However, the "liquid discharge unit" includes not only the head module and the head unit including the above-described liquid discharge head, but also those in which the above-described functional components and mechanisms are integrated.

[0081] The "device for discharging liquid" includes a liquid discharge head, a liquid discharge unit, a head module, a head unit, etc., and a device that drives the liquid discharge head to discharge liquid. The device for discharging liquid includes not only a device that can discharge liquid onto an object to which liquid can adhere, but also a device that discharges liquid into the air or into a liquid.

[0082] This "device for discharging liquid" can also include means related to the feeding, conveying, and paper discharging of an object to which liquid can adhere, as well as other pretreatment devices, post-treatment devices, etc.

[0083] For example, as a "device that discharges a liquid", there are an image forming device that discharges ink to form an image on paper, and a three-dimensional modeling device (3D modeling device) that discharges a modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (3D object).

[0084] Further, the "device that discharges a liquid" is not limited to those in which a meaningful image such as characters or figures is visualized by the discharged 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.

[0085] The above "thing to which a liquid can adhere" means a thing to which a liquid can adhere at least temporarily, such as a thing that adheres and adheres firmly, a thing that adheres and penetrates, etc. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and media such as test cells, and all things to which a liquid adheres are included unless otherwise particularly limited.

[0086] The material of the above "thing to which a liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as a liquid can adhere even temporarily.

[0087] Further, as a "device that discharges a liquid", there is a device in which a liquid discharge head and a thing to which a liquid can adhere move relative to each other, but it is not limited to this. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

[0088] In addition, as a "device that discharges a 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 the purpose of modifying the surface of the paper, etc. 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.

[0089] In the terms of this application, imaging, recording, printing, marking, printing, shaping, etc. are all synonymous.

[0090] What has been described above is an example, and specific effects are achieved for each of the following aspects. (Aspect 1) A liquid ejection head 1 that drives a piezoelectric body 52 to eject liquid from a nozzle 2, wherein a piezoelectric body 52 and a heater 20 are provided on a nozzle forming wall of a pressure chamber 4 communicating with the nozzle 2. In an apparatus for ejecting a material (hereinafter referred to as an ejection material) that is solid at room temperature, such as solder, it is necessary to heat the ejection material to a temperature equal to or higher than the melting temperature by a heater. Therefore, the temperature of the piezoelectric body rises due to the ejection material at a temperature equal to or higher than the melting temperature. When PZT (lead zirconate titanate) with high piezoelectric characteristics is used as the material of the piezoelectric body, the piezoelectricity is lost due to depolarization at a high temperature of 200 °C or higher, and it does not displace even when a voltage is applied. Therefore, the ejection material is limited to a material with a melting temperature of less than 200 °C. Further, when a material such as AlN (aluminum nitride) whose displacement amount does not change even at a high temperature is used as the material of the piezoelectric body, the piezoelectric characteristics are lower than those of PZT. Therefore, in the configuration of Patent Document 1 in which a piezoelectric body is provided on an opposing wall facing the nozzle forming wall of the pressure chamber, sufficient pressure cannot be generated, and there is a possibility that liquid cannot be ejected well from the nozzle. On the other hand, in Aspect 1, a piezoelectric body is provided on the nozzle forming wall, and the nozzle forming wall having the nozzle of the pressure chamber is vibrated to eject the liquid. Thereby, compared with ejecting the liquid by vibrating the opposing wall facing the nozzle forming wall of the pressure chamber, the liquid can be ejected well from the nozzle with a small pressure. Therefore, even if a material with low piezoelectric characteristics and low generated pressure, such as AlN (aluminum nitride), which has high heat resistance and whose displacement amount does not change even at a high temperature, is used as the material of the piezoelectric body, the liquid can be ejected well from the nozzle. As a result, it becomes possible to eject a material with a high melting temperature. In addition, by providing a heating heater on the nozzle forming wall, the discharge material in the pressure chamber can be efficiently heated. Compared with a heater provided on the cover covering the liquid discharge head, the discharge material in the pressure chamber can be maintained at a temperature equal to or higher than the melting temperature with a small heater capacity. As a result, power consumption can be reduced. In addition, the size of the heater can be reduced, and the enlargement of the device can be suppressed.

[0091] (Aspect 2) In Aspect 1, the heating heater 20 is provided closer to the pressure chamber 4 side than the piezoelectric body 52. According to this, as described in the embodiment, the discharge material in the pressure chamber can be efficiently heated compared to a case where the piezoelectric body 52 is provided closer to the pressure chamber 4 side than the heating heater 20.

[0092] (Aspect 3) In Aspect 1, the piezoelectric body 52 is provided closer to the pressure chamber side than the heating heater 20. According to this, as described with reference to FIG. 5, the diaphragm 103 can be efficiently vibrated compared to a case where the heating heater 20 is provided closer to the pressure chamber 4 side than the piezoelectric body 52.

[0093] (Aspect 4) In any one of Aspects 1 to 3, the heat generating portion 21 of the heating heater 20 is made of molybdenum or platinum. According to this, as described in the embodiment, efficient heating due to high resistivity can be performed.

[0094] (Aspect 5) In any one of Aspects 1 to 4, a temperature sensing portion 22 is provided on the nozzle forming wall. According to this, as described in the embodiment, based on the temperature sensed by the temperature sensing portion 22, the heating heater 20 can be controlled, and the liquid in the pressure chamber 4 can be satisfactorily maintained at the target temperature.

[0095] (Aspect 6) In aspect 5, the temperature sensing unit 22 is formed on the same layer as the heating unit 21, and both the temperature sensing unit 22 and the heating unit 21 are made of platinum. According to this, temperature can be detected with high accuracy, and efficient heating can be performed. In addition, the heating unit 21 and the temperature sensing unit 22 can be formed at once, and the manufacturing man-hours can be reduced.

[0096] (Aspect 7) In any of aspects 1 to 6, the piezoelectric body 52 is aluminum nitride or aluminum nitride containing at least one of scandium, yttrium, titanium, magnesium, hafnium, zirconium, tin, chromium, and boron. According to this, as described in the embodiment, the heat resistance of the piezoelectric body 52 can be enhanced. Thereby, even when the piezoelectric body is heated by the heated liquid in the pressure chamber or the heating heater and the temperature rises, it can be displaced well and the liquid can be discharged from the nozzle well.

[0097] (Aspect 8) In any of aspects 1 to 7, the heat generating area of the heating heater 20 is the same as the maximum cross-sectional area perpendicular to the liquid discharge direction of the piezoelectric element 5 including the piezoelectric body 52. According to this, as described in the embodiment, the liquid in the pressure chamber can be heated evenly.

[0098] (Aspect 9) In any of aspects 1 to 8, a second heating heater 3a is provided on the wall portion of the supply liquid chamber such as the common liquid chamber 3 that supplies the liquid to the pressure chamber 4. According to this, as described in the embodiment, the discharged material melted into a liquid can be supplied to the pressure chamber 4.

[0099] (Aspect 10) In any of aspects 1 to 9, the liquid discharged from the nozzle 2 is a molten metal such as solder. According to this, as described in the embodiment, solder bumps and wiring patterns can be formed on the substrate.

[0100] (Aspect 11) In an apparatus for discharging a liquid provided with a liquid discharge head, any one of the liquid discharge heads according to Aspects 1 to 10 was used as the liquid discharge head. According to this, a liquid having a high viscosity in a room temperature environment such as UV ink can be discharged after being made to have a low viscosity. Further, a discharge material that is solid in a room temperature environment such as wax ink or solder can be melted and discharged.

Explanation of Signs

[0101] 1: Liquid discharge head 2: Nozzle 3: Common liquid chamber 3a: Heating heater 4: Pressure chamber 4a: Opening 5: Piezoelectric element 7a: First contact 7b: Second contact 7c: Third contact 7d: Fourth contact 8a: First insulating film 8b: Second insulating film 9a: First lead wiring 9b: Second lead wiring 20: Heating heater 21: Heat generating part 22: Temperature sensing part 23: Insulating film 25: Temperature adjusting part 25a: Adjusting part 25c: Input part 25d: Comparing part 51: First electrode 52: Piezoelectric body 53: Second electrode 100: Pressure chamber substrate 102: Wiring layer 103: Diaphragm 110: Nozzle plate 111: Nozzle forming part 300: Printing apparatus 301: Liquid discharge unit 302: Supply apparatus 302a: Pellet Loading Section 310: Substrate 320: Table 440: Liquid Ejection Unit 441: Head Tank 500: Printing Device

Prior Art Documents

Patent Documents

[0102]

Patent Document 1

Claims

1. A liquid ejection head that drives a piezoelectric body to eject a liquid from a nozzle, characterized in that a piezoelectric body and a heating heater are provided on a nozzle forming wall of a pressure chamber communicating with the nozzle.

2. The liquid ejection head according to claim 1, characterized in that the heating heater is provided closer to the pressure chamber side than the piezoelectric body.

3. The liquid ejection head according to claim 1, characterized in that the piezoelectric body is provided closer to the pressure chamber side than the heating heater.

4. The liquid ejection head according to claim 1, characterized in that the heating heater has a heat generating portion made of molybdenum or platinum.

5. The liquid ejection head according to claim 1, characterized in that a temperature sensing portion is provided on the nozzle forming wall.

6. The liquid ejection head according to claim 5, characterized in that the temperature sensing portion is formed in the same layer as the heat generating portion of the heating heater, and the temperature sensing portion and the heat generating portion are made of platinum.

7. The liquid ejection head according to claim 1, characterized in that the piezoelectric body is aluminum nitride or aluminum nitride containing at least one of scandium, yttrium, titanium, magnesium, hafnium, zirconium, tin, chromium, and boron.

8. The liquid ejection head according to claim 1, characterized in that the heat generating area of the heating heater is equal to the maximum cross-sectional area perpendicular to the liquid ejection direction of the piezoelectric element including the piezoelectric body.

9. The liquid ejection head according to claim 1, characterized in that a second heating heater is provided on a wall portion of a supply liquid chamber that supplies liquid to the pressure chamber.

10. The liquid ejection head according to claim 1, characterized in that the liquid ejected from the nozzle is a molten metal.

11. An apparatus for ejecting a liquid provided with a liquid ejection head, characterized in that the liquid ejection head according to claim 1 is used as the liquid ejection head. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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