JP2009233903A - Liquid jet head and liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet head can secure a sufficient liquid jetting amount even in the case of using high-viscosity liquid, and prevent components contained in the liquid from being deposited in the vicinity of a nozzle, thereby, satisfactorily jet the liquid, and to provide a liquid jet apparatus. <P>SOLUTION: The liquid jet head includes: a nozzle plate 14 with nozzle openings 13 formed in a liquid jet surface thereof, for jetting ink; a flow path forming substrate 12 bonded to the side opposite to the liquid jet surface of the nozzle plate 14, with liquid flow paths including pressure generation chambers 11 communicating with the nozzle openings 13; a piezoelectric element 16 that applies pressure into the pressure generation chamber 11; and a heat medium communicating with the heating path 40, for heating the ink in the liquid flow path. The nozzle plate 14 includes a first plate 14a bonded to the flow path forming substrate 12 and a second plate 14b bonded to the first plate 14a. The second plate 14b is composed of a material having heat-conductivity lower than that of the first plate 14a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, and is particularly useful when applied to a liquid having a high viscosity.

  A typical example of a liquid ejecting head that ejects droplets is an ink jet recording head that ejects ink droplets. As an ink jet recording head, for example, a nozzle plate having nozzles formed therein, a channel forming substrate on which a liquid channel including a plurality of pressure generating chambers communicating with the nozzles is formed, and one of the channel forming substrates are provided. Some have pressure generating means formed on the direction side.

  Recently, there is an increasing demand for printing not only on paper but also on printing objects such as plastic and glass. Since such a print object has low ink absorbability, high-viscosity ink is used to reliably fix the ink to the print object. Ink jet recording heads reduce the viscosity of ink by heating the ink in the liquid flow path because high viscosity ink is too high at room temperature. By reducing the viscosity of the ink, the ink flows stably through the liquid flow path, so that good ink ejection characteristics can be obtained (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-19790

  However, the ink contains a particle component such as a pigment, and when the solvent is evaporated by heating the ink, the particle component may be deposited in the vicinity of the nozzle. When the particle component is deposited in the vicinity of the nozzle, there arises a problem that ink droplets are not ejected straight from the nozzle or the nozzle is clogged with the particle component.

  Such a problem exists not only in an ink jet recording head that ejects ink droplets, but also in other liquid ejecting heads that eject droplets other than ink droplets.

  The present invention has been made in view of such circumstances, and even when a high-viscosity liquid is used, a sufficient discharge amount can be ensured, and components contained in the liquid can be prevented from being deposited near the nozzle. It is an object of the present invention to provide a liquid ejecting head and a liquid ejecting apparatus that can discharge liquid satisfactorily.

The present invention that solves the above-described problems includes a nozzle plate in which a nozzle opening is provided on a liquid ejecting surface that ejects liquid, and a surface that is opposite to the liquid ejecting surface of the nozzle plate and communicates with the nozzle opening. A flow path forming substrate having a liquid flow path including a pressure generating chamber, pressure generating means for applying a pressure for ejecting droplets into the pressure generating chamber, and heating for heating the liquid in the liquid flow path And the nozzle plate includes a first plate bonded to the flow path forming substrate and a second plate bonded to the first plate, and the second plate is The liquid ejecting head is made of a material having a thermal conductivity lower than that of the first plate.
In this aspect, since the thermal conductivity of the second plate is lower than that of the first plate, it is difficult for the heat of the liquid in the liquid flow path to be transmitted to the second plate. For this reason, the temperature rise of the second plate is suppressed. Thereby, since the evaporation of the liquid is suppressed in the vicinity of the nozzle opening, the particle component of the liquid is hardly precipitated in the vicinity of the nozzle opening, and the nozzle opening is not clogged due to the precipitation of the particle component. For this reason, a liquid ejecting head capable of ejecting a liquid straight from the nozzle opening with high accuracy is provided. In addition, a highly reliable liquid jet head that prevents ejection failure due to complete clogging is provided.

  Here, it is preferable to include a cooling means for cooling the second plate. According to this, since the temperature in the vicinity of the nozzle opening of the second plate is cooled, the evaporation of the liquid is further suppressed in the vicinity of the nozzle opening, and the precipitation of the particle component can be reliably prevented.

  Moreover, it is preferable that the said cooling means is a cooling element provided in the said liquid ejection surface side of the said 2nd plate. According to this, precipitation of a particle component can be prevented more reliably.

  Moreover, it is preferable that the said heating means is the conducting wire for heating arrange | positioned at the said flow-path formation board | substrate. According to this, since the liquid flowing through the pressure generating chamber close to the liquid discharge side is heated, it is possible to reliably heat the liquid and reduce its viscosity.

  Moreover, it is preferable that the said heating means is a heat medium which circulates through the heating flow path formed in the said flow path formation board | substrate. According to this, since the liquid flowing through the pressure generating chamber close to the liquid discharge side is heated, it is possible to reliably heat the liquid and reduce its viscosity.

  Further, it is preferable that a water repellent film is provided on the liquid ejection surface of the second plate. According to this, it can prevent that the liquid from a nozzle opening adheres to the surface of a 2nd plate.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head.
According to this aspect, it is possible to realize a liquid ejecting apparatus that improves reliability and is excellent in liquid ejection characteristics.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a schematic cross-sectional view showing an ink jet recording head that is an example of a liquid jet head according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of a main part of the ink jet recording head.

  As shown in FIGS. 1 and 2, the ink jet recording head 10 of this embodiment includes a flow path forming substrate 12 having a plurality of pressure generation chambers 11 and a plurality of nozzle openings 13 communicating with each pressure generation chamber 11. The nozzle plate 14 provided, the vibration plate 15 provided on the surface of the flow path forming substrate 12 opposite to the nozzle plate 14, and the region corresponding to each pressure generating chamber 11 on the vibration plate 15. A piezoelectric element unit 17 having a piezoelectric element 16 and a head case 19 having an accommodating portion 18 that is fixed on the vibration plate 15 and accommodates the piezoelectric element unit 17 are included.

  In the flow path forming substrate 12, a plurality of pressure generating chambers 11 are partitioned by a partition wall and arranged in parallel in the width direction on the surface layer portion on one side. For example, in the present embodiment, a plurality of pressure generation chambers 11 are arranged in parallel on the flow path forming substrate 12, and ink is supplied to each pressure generation chamber 11 outside the row of each pressure generation chamber 11. A reservoir 21 is provided penetrating the flow path forming substrate 12 in the thickness direction. Each pressure generating chamber 11 and the reservoir 21 communicate with each other via an ink supply path 22. In this embodiment, the ink supply path 22 is formed with a width narrower than that of the pressure generation chamber 11, and plays a role of maintaining a constant flow path resistance of ink flowing from the reservoir 21 into the pressure generation chamber 11. Further, a nozzle communication hole 23 penetrating the flow path forming substrate 12 is formed on the end side of the pressure generating chamber 11 opposite to the reservoir 21. The reservoir 21 communicates with an ink introduction path 41 formed so as to penetrate in the thickness direction of the head case 19. The ink introduction path 41 is a flow path that guides ink from an ink cartridge (not shown) to the reservoir 21. That is, a liquid flow path including the reservoir 21, the ink supply path 22, the pressure generation chamber 11, and the nozzle communication hole 23 is formed on the flow path forming substrate 12.

  As will be described in detail later, as an example of a heating unit that heats ink in the liquid flow path, a heating flow path 40 through which a heat medium flows is formed in the flow path forming substrate 12. Since the ink is heated by such a heat medium and the viscosity thereof is lowered, the ink can stably flow through the pressure generating chamber 11 and the like, and good ink ejection characteristics can be obtained.

  In this embodiment, the flow path forming substrate 12 is made of a silicon single crystal substrate, and the pressure generating chamber 11 and the like provided in the flow path forming substrate 12 are formed by etching the flow path forming substrate 12. ing.

  On one surface side of the flow path forming substrate 12, a nozzle plate 14 having a nozzle opening 13 is bonded via an adhesive or a heat welding film, and each nozzle opening 13 is provided on the flow path forming substrate 12. The pressure generating chambers 11 communicate with each other through the nozzle communication holes 23.

  The nozzle plate 14 is composed of a first plate 14a joined to the flow path forming substrate 12 and a second plate 14b joined to the first plate 14a. The first plate 14a is made of a material having a thermal conductivity lower than that of the first plate 14a. The material of the second plate 14b is preferably silicon or glass, for example, and the material of the first plate 14a in this case is preferably SUS. Moreover, the 1st plate 14a and the 2nd plate 14b may be formed from the single layer, and may be formed from the multiple layer. When formed from a plurality of layers, the layer on the liquid ejection surface of the nozzle plate 14 (the surface on the side opposite to the flow path forming substrate 12 of the second plate 14b) is directed toward the layer on the flow path forming substrate 12 side. A nozzle plate formed so as to have a high thermal conductivity is used.

  Thus, if the thermal conductivity of the second plate 14b is lower than that of the first plate 14a, the heat of the ink in the pressure generating chamber 11 and the like is difficult to transfer to the second plate 14b. Temperature rise is suppressed. Thereby, since the evaporation of the ink is suppressed in the vicinity of the nozzle opening 13, the particle component of the ink is difficult to deposit in the vicinity of the nozzle opening 13, and the clogging of the nozzle opening 13 due to the precipitation of the particle component is prevented. For this reason, an ink jet recording head capable of ejecting ink straight from the nozzle opening 13 with high accuracy is provided. Further, there is provided an ink jet recording head having high reliability in which ejection failure due to complete clogging is prevented.

  Further, due to the difference in thermal conductivity described above, the temperature of the first plate 14a is kept at the same temperature as the ink in the liquid flow path because the heat is not easily transmitted to the second plate 14b. . For this reason, in the area | region which the ink of the 1st plate 14a touches directly, for example, area | region A1 which opposes the reservoir | reserver 21 of the 1st plate 14a, and area | region A2 which opposes the nozzle communicating hole 23, the reservoir | reserver 21 and the nozzle communicating hole 23 of The temperature of the ink can be maintained without taking the heat of the ink. As a result, the viscosity of the ink can be reduced, and a stable distribution of the ink in the liquid channel can be ensured.

  Note that a cooling means for cooling the second plate 14b may be provided in the ink jet recording head so that the temperature on the liquid ejection surface side of the nozzle plate 14 is low. According to this, the vicinity of the nozzle opening 13 can be more reliably maintained at a low temperature, and the precipitation of the particle component in the vicinity of the nozzle opening 13 can be more reliably prevented. An example of the cooling means will be described later.

  In this embodiment, a water repellent film 42 is provided on the surface of the second plate 14b so that ink from the nozzle openings 13 does not adhere to the surface of the second plate 14b.

  Further, a diaphragm 15 is bonded to the other surface side of the flow path forming substrate 12, that is, the opening surface side of the pressure generating chamber 11, and each pressure generating chamber 11 is sealed by the diaphragm 15.

  The diaphragm 15 is formed of a composite plate of an elastic film 24 made of an elastic member such as a resin film and a support plate 25 made of, for example, a metal material that supports the elastic film 24, and is elastic. The membrane 24 side is bonded to the flow path forming substrate 12. For example, in the present embodiment, the elastic film 24 is made of a PPS (polyphenylene sulfide) film, and the support plate 25 is made of a stainless steel plate (SUS). In addition, an island portion 26 with which the tip end portion of the piezoelectric element 16 abuts is provided in a region of the diaphragm 15 facing each pressure generating chamber 11. That is, a thin portion 27 thinner than other regions is formed in a region of the diaphragm 15 facing the peripheral edge of each pressure generating chamber 11, and an island portion 26 is provided inside each thin portion 27. ing. Further, in the present embodiment, in the region facing the reservoir 21 of the vibration plate 15, as in the case of the thin portion 27, the support portion 25 is removed by etching, and the compliance portion 28 configured substantially only by the elastic film 24 is provided. Is provided. The compliance portion 28 absorbs the pressure change when the elastic film 24 of the compliance portion 28 is deformed when the pressure change in the reservoir 21 occurs, and always keeps the pressure in the reservoir 21 constant. Fulfill.

  Each piezoelectric element 16 constituting the piezoelectric element unit 17 is fixed in a state where the tip of the active region is in contact with the island portion 26 of the diaphragm 15.

  Here, the piezoelectric element 16 which is a pressure generating means for generating a pressure for ejecting ink droplets into the pressure generating chamber 11 is integrally formed in one piezoelectric element unit 17 in this embodiment. That is, a piezoelectric element forming member 32 is formed by laminating piezoelectric materials 29 and electrode forming materials 30 and 31 alternately in a sandwich shape, and the piezoelectric element forming members 32 correspond to the respective pressure generating chambers 11. Each piezoelectric element 16 is formed by cutting on the comb teeth. That is, in this embodiment, the plurality of piezoelectric elements 16 are integrally formed. An inactive region that does not contribute to the vibration of the piezoelectric element 16 (piezoelectric element forming member 32), that is, the base end side of the piezoelectric element 16 is fixed to the fixed substrate 33. A circuit board 35 having a wiring 34 for supplying a signal for driving each piezoelectric element 16 is connected to the surface opposite to the fixed board 33 in the vicinity of the base end portion of the piezoelectric element 16. In the embodiment, the piezoelectric element unit 17 is configured by the piezoelectric element 16 (piezoelectric element forming member 32), the fixed substrate 33, and the circuit substrate 35.

  Such a piezoelectric element unit 17 is fixed in a state where the tip of the piezoelectric element 16 is in contact with the island part 26 of the diaphragm 15 described above. For example, in the present embodiment, the head case 19 is fixed on the diaphragm 15 as described above, and the piezoelectric element unit 17 is accommodated in the accommodating portion 18 of the head case 19 and the piezoelectric element 16 is fixed. The fixed substrate 33 thus fixed is fixed to the head case 19 on the surface opposite to the piezoelectric element 16.

  The head case 19 is provided with a plurality of accommodating portions 18 in which the piezoelectric element units 17 are accommodated.

  In the present embodiment, three accommodating portions 18 are provided side by side, and one piezoelectric element unit 17 is disposed in one accommodating portion 18. That is, the ink jet recording head 10 of the present embodiment is provided with a total of three piezoelectric element units 17. In the ink jet recording head 10 of the present embodiment, since the rows of nozzle openings 13 are provided for each piezoelectric element unit 17, three rows of nozzle openings 13 are provided.

  On the head case 19, a wiring board 37 provided with a plurality of conductive pads 36 to which the wirings 34 of the circuit board 35 are connected is fixed. The substrate 37 is substantially blocked. The wiring board 37 is formed with a slit-like opening 38 in a region facing the housing part 18 of the head case 19, and the circuit board 35 is drawn out of the housing part 18 from the opening 38 of the wiring board 37. It is.

  Note that one opening 38 of the wiring board 37 is provided for each accommodating portion 18, that is, three openings are provided in the present embodiment, and one piezoelectric element unit 17 provided in one accommodating portion 18 is provided. One circuit board 35 connected to is pulled out from one opening 38.

  In this embodiment, the circuit board 35 constituting the piezoelectric element unit 17 is a flexible printed circuit board (FPC) on which a driving IC (not shown) for driving the piezoelectric element 16 is mounted, for example, a tape carrier package (TCP). And chip-on-film (COF), flexible flat cable (FFC), and the like. And each wiring 34 of the circuit board 35 is connected to the electrode forming materials 30 and 31 which comprise the piezoelectric element 16 by the solder | pewter, anisotropic conductive material, etc. in the base end part side, for example. On the other hand, on the tip end side, each wiring 34 is joined to each conductive pad 36 of the wiring board 37. Specifically, each wiring 34 is connected to the wiring board 37 in a state where the front end of the circuit board 35 drawn out of the housing portion 18 from the opening 38 of the wiring board 37 is bent along the surface of the wiring board 37. The conductive pads 36 are joined via solder (not shown).

  In such an ink jet recording head 10, when ejecting ink droplets, the volume of each pressure generating chamber 11 is changed by deformation of the piezoelectric element 16 and the diaphragm 15 to eject ink droplets from a predetermined nozzle opening 13. It is like that. Specifically, when ink is supplied to the reservoir 21 from an ink cartridge (not shown), the ink is distributed to each pressure generating chamber 11 via the ink supply path 22. Actually, the piezoelectric element 16 is contracted by applying a voltage to the piezoelectric element 16. As a result, the diaphragm 15 is deformed together with the piezoelectric element 16 to expand the volume of the pressure generating chamber 11, and ink is drawn into the pressure generating chamber 11. Then, after the ink is filled up to the nozzle opening 13, the voltage applied to the electrode forming materials 30 and 31 of the piezoelectric element 16 is released according to a recording signal supplied via the wiring substrate 37. As a result, the piezoelectric element 16 is expanded to return to the original state, and the diaphragm 15 is also displaced to return to the original state. As a result, the volume of the pressure generation chamber 11 contracts, the pressure in the pressure generation chamber 11 increases, and ink droplets are ejected from the nozzle openings 13.

  Here, the heating flow path which is an example of a heating means is demonstrated using FIG. FIG. 3 is a cross-sectional view taken along line A-A ′ of FIG. 2.

  As shown in the figure, the flow path forming substrate 12 includes a reservoir 21 in the partition wall 43 that defines the pressure generation chamber 11, the outside of the pressure generation chamber 11, and a groove portion that is continuously provided between the pressure generation chambers 11. A heating flow path 40 is provided. A heating medium such as water heated to a predetermined temperature is circulated through the heating channel 40 by a heating medium supply means (not shown), and the heat of the heating medium heats the ink via the partition wall 43. Yes.

  According to such a heat medium flowing through the heating flow path 40, the ink flowing from the reservoir 21 near the ink ejection side to the nozzle communication hole 23 in the liquid flow path is heated. It can be reliably heated to lower its viscosity.

  Of course, not only when the ink in the nozzle communication hole 23 is heated from the reservoir 21, but also the ink flowing through the ink cartridge and the ink introduction path 41 may be heated. Further, the heating means is not limited to the heat medium flowing through the heating flow path 40. For example, when a flow path forming substrate made of SUS is used, a voltage may be applied to the flow path forming substrate to heat the entire flow path forming substrate, and the heat may be used to heat the ink. Further, similarly to the heating flow path 40, heating conductors are disposed outside the reservoir 21 and the pressure generation chamber 11 in the partition wall 43 defining the pressure generation chamber 11 and between the pressure generation chambers 11. You may heat the ink of a liquid flow path with the heat which arises by sending an electric current.

  Here, the cooling element which is an example of a cooling means is demonstrated using FIG. 4A and 4B are a plan view and a cross-sectional view taken along the line A-A ′ of the liquid ejection surface side of the nozzle plate. As illustrated, a cooling element 44 is disposed on the surface (liquid ejection surface) of the second plate 14b so as to surround the nozzle row of the nozzle openings 13. As the cooling element 44, for example, a Peltier element is used. The cooling element 44 is configured such that the second plate 14b is cooled, whereby the vicinity of the nozzle row of the second plate 14b is cooled and the ink is evaporated near the nozzle opening 13. It is possible to suppress the precipitation of the ink particle component in the nozzle opening 13. For this reason, an ink jet recording head capable of ejecting ink with higher accuracy and reliably preventing clogging of the nozzle openings 13 is provided.

  The cooling means is not limited to the cooling element 44. For example, the cooling means may be a refrigerant having a temperature lower than that of the heated ink through the refrigerant flow path provided in the second plate 14b.

  These ink jet recording heads constitute a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and are mounted on the ink jet recording apparatus. FIG. 5 is a schematic view showing an example of the ink jet recording apparatus.

  As shown in FIG. 5, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S which is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is designed to be transported.

  Although an ink jet recording head has been described as an example of a liquid ejecting head, the present invention is intended for a wide range of liquid ejecting heads in general and manufactures a liquid ejecting head that ejects liquid droplets other than ink droplets. Of course, the method can also be applied. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 2 is a schematic cross-sectional view of a recording head according to an embodiment. FIG. 3 is a cross-sectional view of a main part of the recording head according to the embodiment. It is sectional drawing of the flow-path formation board | substrate which concerns on embodiment. It is the top view and sectional view of a nozzle plate concerning an embodiment. 1 is a schematic view of an ink jet recording apparatus according to an embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Recording head, 11 Pressure generating chamber, 12 Flow path formation board, 13 Nozzle opening, 14 Nozzle plate, 15 Diaphragm, 16 Piezoelectric element, 17 Piezoelectric element unit, 18 accommodating part, 19 Head case, 21 Reservoir, 22 Ink supply Path, 23 nozzle communication hole, 24 elastic film, 25 support plate, 26 island part, 27 thin part, 28 compliance part, 29 piezoelectric material, 30, 31 electrode forming material, 32 piezoelectric element forming member, 33 fixed substrate, 34 wiring 35 circuit board, 36 conductive pad, 37 wiring board, 38 opening, 40 heating flow path, 41 ink introduction path, 42 water repellent film, 43 partition wall, 44 cooling element

Claims (7)

A nozzle plate provided with nozzle openings on a liquid ejection surface for ejecting liquid;
A flow path forming substrate having a liquid flow path including a pressure generating chamber joined to a surface of the nozzle plate opposite to the liquid ejection surface and communicating with the nozzle opening;
Pressure generating means for applying pressure for ejecting droplets into the pressure generating chamber;
Heating means for heating the liquid in the liquid flow path,
The nozzle plate includes a first plate joined to the flow path forming substrate and a second plate joined to the first plate,
The liquid ejecting head according to claim 1, wherein the second plate is made of a material having a thermal conductivity lower than that of the first plate. The liquid ejecting head according to claim 1,
A liquid ejecting head comprising cooling means for cooling the second plate. The liquid ejecting head according to claim 2,
The liquid ejecting head, wherein the cooling means is a cooling element provided on the liquid ejecting surface side of the second plate. In the liquid jet head according to any one of claims 1 to 3,
The liquid ejecting head according to claim 1, wherein the heating means is a heating wire disposed on the flow path forming substrate. In the liquid jet head according to any one of claims 1 to 3,
The liquid ejecting head according to claim 1, wherein the heating unit is a heat medium that circulates in a heating flow path formed on the flow path forming substrate. In the liquid jet head according to any one of claims 1 to 5,
A liquid ejecting head, wherein a water repellent film is provided on the liquid ejecting surface of the second plate.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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