JP7326091B2 - Inkjet head and inkjet printer - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to inkjet heads and inkjet printers.

2. Description of the Related Art Ink jet printers having a so-called shear mode type ink jet head structure that ejects ink droplets from nozzles using shear deformation of a piezoelectric member are known. In such a structure, a nozzle plate provided with nozzle holes and a piezoelectric member forming pressure chambers for holding ink are joined together so that the nozzles and the pressure chambers communicate with each other. Adhesives such as silane coupling agents, plasma treatments, and the like are used for these connections.

Japanese Patent No. 6155370 JP 2009-292917 A JP-A-7-171971

The problem to be solved by the present invention is to provide an inkjet head with excellent stability and an inkjet printer equipped with such an inkjet head.

According to embodiments, an inkjet head is provided. An inkjet head includes a nozzle plate, a piezoelectric member, and a fluorine compound layer. The nozzle plate includes nozzles that eject ink toward the recording medium. The piezoelectric member forms a pressure chamber at a position communicating with the nozzle, and changes the pressure in the pressure chamber to eject the ink in the pressure chamber. The fluorine compound layer is located at least between the piezoelectric member and the nozzle plate. The fluorine compound layer includes a first layer, a second layer and a third layer. The first layer is located on the nozzle plate side. The second layer is located on the piezoelectric member side. A third layer is located between the first and second layers. The X-ray photoelectron spectroscopy spectra of the first to third layers each contain peaks belonging to _CF2 groups. The peak area PA3 of _CF2 groups contained in the X-ray photoelectron spectroscopy spectrum of the third layer is larger than the peak area PA1 of _CF2 groups contained in the X-ray photoelectron spectroscopy spectrum of the first layer, and It is larger than the peak area PA2 of _CF2 groups contained in the X-ray photoelectron spectroscopy spectrum.

According to another embodiment, an inkjet printer is provided. An inkjet printer includes an inkjet head and a medium holding mechanism according to the embodiment. A medium holding mechanism holds a recording medium facing the inkjet head.

1 is a perspective view showing an inkjet head according to an embodiment; FIG. 2 is an exploded perspective view showing an actuator plate, a frame, and a nozzle plate that constitute the inkjet head according to the embodiment; FIG. 1 is a partially cut top view of an inkjet head according to an embodiment; FIG. FIG. 4 is a cross-sectional view along a plane perpendicular to the Y-axis showing part of the inkjet head shown in FIG. 3 ; FIG. 4 is a cross-sectional view schematically showing a state in which an electrode protective film is bonded to an electrode; FIG. 2 is a cross-sectional view schematically showing first to third layers included in a fluorine compound layer; The graph which shows an example of the XPS spectrum of a 1st layer and a 3rd layer. 1 is a schematic diagram showing an inkjet printer according to an embodiment; FIG.

1. Inkjet head 1-1. Configuration Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a perspective view showing an on-demand type inkjet head 1 used by being mounted on a head carriage of an inkjet printer, according to an embodiment. In the following description, an orthogonal coordinate system consisting of X-, Y-, and Z-axes is used. For the sake of convenience, the direction indicated by the arrow in the drawing is the positive direction. The X-axis direction corresponds to the print width direction. The Y-axis direction corresponds to the direction in which the recording medium is conveyed. The positive direction of the Z axis is the direction facing the recording medium.

Schematically described with reference to FIG. 1, the ink jet head 1 comprises an ink manifold 10, an actuator plate 20, a frame 40 and a nozzle plate 50. As shown in FIG.

The actuator plate 20 has a rectangular shape whose longitudinal direction is the X-axis direction. Examples of materials for the actuator plate 20 include alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), aluminum nitride (AlN), and lead zirconate titanate (PZT: Pb(Zr, Ti)O ₃ ) and the like.

The actuator plate 20 is superimposed on the ink manifold 10 so as to close the open end of the ink manifold 10 . The ink manifold 10 is connected to the ink cartridges via an ink supply pipe 11 and an ink return pipe 12 .

A frame 40 is mounted on the actuator plate 20 . A nozzle plate 50 is mounted on the frame 40 . A plurality of nozzles N are provided on the nozzle plate 50 at predetermined intervals so as to form two rows each extending in the X-axis direction and arranged in the Y-axis direction.

FIG. 2 is an exploded perspective view of the actuator plate 20, the frame 40 and the nozzle plate 50 that constitute the inkjet head according to the embodiment. FIG. 3 is a partially cut top view of the inkjet head according to the embodiment. 4 is a cross-sectional view along a plane perpendicular to the Y-axis showing part of the inkjet head shown in FIG. 3. FIG.
The inkjet head 1 is of a so-called shear mode shared wall side shooter type.

As shown in FIGS. 2 and 3, the actuator plate 20 is provided with a plurality of ink supply ports 21 spaced apart along the X-axis direction so as to form a row at the center in the Y-axis direction. there is In the actuator plate 20, a plurality of ink discharge ports 22 are arranged in the X-axis direction so as to form rows at positions spaced apart from the rows of the ink supply ports 21 in the Y-axis plus direction and the Y-axis minus direction. are spaced apart along the

A plurality of piezoelectric members 30 are provided between the central row of ink supply ports 21 and one row of ink discharge ports 22 . These piezoelectric members 30 form a row extending in the X-axis direction. A plurality of piezoelectric members 30 are also provided between the central row of ink supply ports 21 and the row of ink discharge ports 22 on the other side. These piezoelectric members 30 also form a row extending in the X-axis direction.

Each row of piezoelectric members 30 is composed of a first piezoelectric body 301 and a second piezoelectric body 302 laminated on the actuator plate 20, as shown in FIG. Materials for the first piezoelectric body 301 and the second piezoelectric body 302 include, for example, lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), and the like. The first piezoelectric body 301 and the second piezoelectric body 302 are polarized in opposite directions along the thickness direction.

A laminate composed of the first piezoelectric body 301 and the second piezoelectric body 302 is provided with a plurality of grooves each extending in the Y-axis direction and arranged in the X-axis direction. These grooves are open on the second piezoelectric body 302 side and have a depth greater than the thickness of the second piezoelectric body 302 . Hereinafter, a portion of this laminate sandwiched between adjacent grooves will be referred to as a channel wall. These channel walls each extend in the Y-axis direction and are aligned in the X-axis direction.

The piezoelectric member 30 forms a pressure chamber 32 at a position communicating with a nozzle N, which will be described later, and changes the pressure in the pressure chamber 32 to eject the ink in the pressure chamber 32 . The pressure chamber 32 through which the ink flows is a space located in a groove between two adjacent channel walls. The width of the pressure chamber 32, here, the dimension of the pressure chamber 32 along the X-axis direction is preferably in the range of 20 μm or more and 100 μm or less, more preferably in the range of 50 μm or more and 80 μm or less.

Electrodes 33 are formed on the sidewalls and bottom surrounding the pressure chamber 32 . That is, the electrodes 33 are formed in the portions of the piezoelectric member 30 adjacent to the pressure chambers 32 . These electrodes 33 are connected to wiring patterns 31 extending along the Y-axis direction. The electrodes 33 apply driving pulses to the piezoelectric member 30 .

An electrode protection film 34 is formed on the surface of the actuator plate 20 including the electrodes 33 and the wiring pattern 31 except for the connection portion with the flexible printed circuit board, which will be described later. The electrode protective film 34 has insulating properties. The electrode protective film 34 is, for example, a film containing a fluorine compound. A fluorine compound is, for example, a fluorine resin containing a repeating unit containing a cyclic structure. The cyclic structure is preferably an aliphatic ring, more preferably a structure containing a heterocyclic ring composed of carbon and oxygen.

FIG. 5 is a cross-sectional view schematically showing a state in which the electrode protective film is bonded to the electrode. The electrode protection film 34 shown in FIG. 5 is a film made of a fluorine compound containing a five-membered ring structure. The structure shown in FIG. 5 represents the monomer of the fluorine compound. A fluorine compound having the structure shown in FIG. 5 can be a polymer containing a five-membered ring structure in a repeating unit. The electrode protective film 34 is bonded to the electrode 33 via an ether bond. The fluorine compound shown in FIG. 5 is, for example, Cytop (registered trademark) manufactured by AGC Corporation.

As the electrode protection film 34, a film containing a compound having a polyparaxylylene skeleton, that is, a parylene film may be used. The electrode protection film 34 may be a laminate of a parylene film and a film containing a fluorine compound. The electrode protection film 34 may be omitted.

As shown in FIG. 4, the nozzle plate 50 includes a nozzle plate base material 501, a liquid-repellent film 502 provided on its medium facing surface (ejection surface for ejecting ink from the nozzles N), and a back surface of the medium facing surface ( and a liquid-repellent film 503 provided on the surface in contact with the pressure chamber 32 . The nozzle plate base material 501 is made of, for example, a resin film such as a polyimide film. The liquid-repellent films 502 and 503 are, for example, films containing a fluorine compound. As the film containing a fluorine compound, the same film as the electrode protection film 34 described above can be used. The liquid-repellent films 502 and 503 may be made of the same material or may be made of different materials.

The frame 40 has an opening as shown in FIGS. This opening is smaller than the actuator plate 20 and larger than the area of the actuator plate 20 where the ink supply port 21, the piezoelectric member 30, and the ink discharge port 22 are provided. The frame 40 is made of ceramics, for example. The frame 40 is joined to the actuator plate 20 with an adhesive layer containing a fluorine compound (not shown). The adhesive layer is a fluorine compound layer having the same configuration as the fluorine compound layer 70 described later. The frame 40 may be joined to the actuator plate 20 with an adhesive other than a fluorine compound. Frame 40 may be omitted.

Nozzle plate 50 is larger than the opening of frame 40 . The nozzle plate 50 is joined to the frame 40 by an adhesive layer (not shown). The adhesive layer is a fluorine compound layer having the same configuration as the fluorine compound layer 70 described later. The nozzle plate 50 may be joined to the frame 40 with an adhesive other than a fluorine compound.

The nozzle plate 50 is provided with a plurality of nozzles N for ejecting ink toward the recording medium. These nozzles N form two rows corresponding to the pressure chambers 32 . The diameter of the nozzle N increases in the direction of the pressure chamber 32 from the surface facing the recording medium. The dimension of the nozzle N is set to a predetermined value according to the ink ejection amount. The nozzle N can be formed, for example, by performing laser processing using an excimer laser.

The actuator plate 20, frame 40 and nozzle plate 50 are integrated as shown in FIG. 1 to form a hollow structure. The area surrounded by the actuator plate 20, frame 40 and nozzle plate 50 is the ink flow chamber. Ink is supplied from the ink manifold 10 to the ink circulation chamber through the ink supply port 21 , passes through the pressure chamber 32 , and surplus ink is circulated back to the ink manifold 10 through the ink discharge port 22 . A part of the ink is ejected from the nozzle N while flowing through the pressure chamber 32 and used for printing.

A flexible printed circuit board 60 is connected to the wiring pattern 31 at a position on the actuator plate 20 and outside the frame 40 . A drive circuit 61 for driving the piezoelectric member 30 is mounted on the flexible printed circuit board 60 .

The nozzle plate 50 is joined to the piezoelectric member 30 by the fluorine compound layer 70 . A fluorine compound layer 70 is located between the piezoelectric member 30 and the nozzle plate 50 . The fluorine compound layer 70 is provided between the portion 302a of the surface of the piezoelectric member 30 provided with the grooves, which is not covered with the electrode 33, and the surface of the nozzle plate 50 opposite to the surface provided with the liquid-repellent film 502. positioned.

The fluorine compound layer 70 has a three-layer structure consisting of first to third layers. The fluorine compound layer 70 is considered to have the structure shown in FIG. FIG. 6 is a cross-sectional view schematically showing the first to third layers included in the fluorine compound layer. The fluorine compound layer 70 shown in FIG. 6 includes a first layer 701 , a second layer 702 and a third layer 703 .

It can be confirmed by X-ray photoelectron spectroscopy (XPS) analysis that the fluorine compound layer 70 includes the first to third layers. That is, by performing XPS analysis at regular intervals along the thickness direction of the fluorine compound layer 70, it can be confirmed that the fluorine compound layer 70 has three layer structures with different XPS spectra.

The first layer 701 is located closest to the nozzle plate 50 . The XPS spectrum of the first layer 701 contains peaks belonging to _CF2 groups. A second layer 702 is located closest to the piezoelectric member 30 . The XPS spectrum of the second layer 702 contains peaks belonging to _CF2 groups. The XPS spectrum of the second layer is typically the same as the XPS spectrum of the first layer 701 . A third layer 703 is located between the first layer 701 and the second layer 702 . The XPS spectrum of the third layer is larger than the area PA1 of the peaks belonging to the _CF2 groups contained in the XPS spectrum of the first layer 701 and the area of the peaks belonging to the _CF2 groups contained in the XPS spectrum of the second layer 702. It contains peaks belonging to _CF2 groups with areas larger than area PA2. That is, the third layer 703 contains more CF ₂ groups than the first layer 701 and the second layer 702 . The fluorine compound layer 70 having such a three-layer structure exhibits excellent durability and adhesiveness. Also, the fluorine compound layer 70 can be repeatedly bonded and peeled. Details of this characteristic will be described later.

The ratio PA3/PA1 between the peak area PA3 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the third layer 703 and the peak area PA1 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the first layer 701 is It is preferably 2 or more and 3 or less. Also, the ratio PA3/PA2 between the area PA3 and the peak area PA2 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the second layer 702 is preferably 2 or more and 3 or less. The fluorine compound layer 70 having the ratio PA3/PA1 and the ratio PA3/PA2 within this range is superior in durability and adhesiveness.

The XPS spectra of the first layer 701 and the second layer 702 may further contain at least one atomic group selected from the group consisting of CF ₂ O groups and CF groups. The XPS spectra of the first layer 701 and the second layer 702 preferably contain _CF2O groups. The fact that the first layer 701 and the second layer 702 contain CF ₂ O groups indicates that the fluorine compound layer 70 is a film formed by bonding fluorine compounds having the ring structure shown in FIG. obtain.

FIG. 7 is a graph showing an example of XPS spectra of the first layer and the third layer. The XPS spectra of the first layer 701 and the third layer 703 shown in FIG. 7 both contain CF ₂ O groups, CF ₂ groups and CF groups. As shown in FIG. 7, in the XPS spectrum, the peak attributed to the CF ₂ O bond appears on the higher bond energy side within the range of 1 eV or more and 1.3 eV or less than the bond energy of the peak attributed to the CF ₂ bond. The peak attributed to the CF bond appears on the lower bond energy side within a range of 1.7 eV or more and 2 eV or less than the bond energy of the peak attributed to the _CF2 bond.

The thickness of the fluorine compound layer 70 is preferably 1 μm or more and 5 μm or less. When the thickness is within this range, good adhesion can be maintained for a longer period of time. The ratio of the thickness of the third layer 703 to the thickness of the fluorine compound layer 70 is preferably 0.5% or more and 2% or less.

1-2. Ink Ejection Hereinafter, the operation of the piezoelectric member 30 will be described with reference to FIGS. 3 and 4. FIG. Here, the operation will be described assuming that pressure chambers 32 are also formed on both sides of the central pressure chamber 32 . Assume that the electrodes 33 corresponding to the three adjacent pressure chambers 32 are electrodes A, B, and C, respectively, and the electrode 33 corresponding to the central pressure chamber 32 is electrode B.

In order to eject ink from the nozzle N, first, for example, a voltage pulse having a potential higher than that of the electrodes A and C on both sides is applied to the center electrode B to generate an electric field in a direction perpendicular to the channel wall. Let Thus, the channel walls are driven in shear mode, and the pair of channel walls sandwiching the central pressure chamber 32 are deformed such that the central pressure chamber 32 expands.

Next, a voltage pulse with a potential higher than that of the central electrode B is applied to the adjacent electrodes A and C to generate an electric field perpendicular to the channel wall. Thus, the channel walls are driven in shear mode, and the pair of channel walls sandwiching the central pressure chamber 32 are deformed such that the central pressure chamber 32 contracts. By this operation, pressure is applied to the ink in the central pressure chamber 32, and the ink is ejected from the nozzle N corresponding to this pressure chamber 32 to land on the recording medium. Thus, in this inkjet head 1, ink is ejected from the nozzles N using the piezoelectric member 30 as an actuator.

In a printing process using this inkjet head 1, for example, all nozzles N are divided into three groups, and the driving operation described above is performed in three cycles by time-division control, thereby printing onto a recording medium.

1-3. Manufacturing Method A method of manufacturing the inkjet head 1 shown in FIGS. 1 to 4 will be described.
First, as shown in FIGS. 2 and 3, a structure in which the piezoelectric member 30 is provided on the actuator plate 20 is formed by a conventionally known method. Next, as shown in FIGS. 2 to 4, wiring patterns 31 and electrodes 33 are formed on the piezoelectric member 30 and the actuator plate 20 by plating, for example.

Next, as shown in FIG. 4, the electrode 33 and the portion 302a of the surface of the second piezoelectric body 302 that is not covered with the electrode 33 are coated with a fluorine compound-containing liquid to form a coating film. . As a method for forming the coating film, for example, a spray method, a spin coating method, or an immersion method is used. The fluorine compound-containing liquid includes, for example, a fluorine compound and a fluorine-based organic solvent capable of dissolving the fluorine compound. The fluorine compound can be a polymer that forms a cyclic structure at a specific temperature (so-called cyclic bonding temperature) and has a structure containing the cyclic structure as a repeating unit. As the fluorine compound, CYTOP (registered trademark) type A manufactured by AGC Corporation can be used.

This coating film is subjected to heat treatment to form the electrode protection film 34 . In the heat treatment, the heating temperature is set to the cyclic bond temperature or higher, preferably 100° C. or higher and 200° C. or lower, and the heating time is preferably set to 30 minutes or longer and 2 hours or shorter. The surface of the electrode 33 and the portion 302a of the second piezoelectric body 302 may be pretreated prior to the application of the fluorine compound-containing liquid. Examples of the pretreatment include application of a silane coupling agent, plasma treatment, and the like. By performing such a pretreatment, the adhesion between the electrode 33 and the portion 302a of the second piezoelectric body 302 and the electrode protective film 34 can be enhanced. The structure shown in FIG. 5 can be obtained by using CYTOP (registered trademark) manufactured by AGC Corporation as the fluorine compound.

Next, both main surfaces of the frame 40 are coated with a fluorine compound-containing liquid to form coating films. As the fluorine compound-containing liquid, the same liquid as described above can be used. An adhesive layer (not shown) is obtained by heat-treating the coating film in the same manner as described above. As shown in FIG. 2, the frame 40 is attached to the upper surface of the actuator plate 20 via an adhesive layer provided on one main surface of the frame 40 .

Next, a nozzle plate 50 having liquid-repellent films 502 and 503 is prepared. Specifically, first, the nozzle plate base material 501 is prepared. The nozzle plate base material 501 is provided with holes that serve as nozzles. When holes to be nozzles are provided after the liquid-repellent films 502 and 503 are formed, the nozzle plate base material 501 may be one without holes.

A fluorine compound-containing liquid is applied to both surfaces of the nozzle plate base material 501 to form a coating film. As the fluorine compound-containing liquid, the same liquid as described above can be used. The liquid-repellent films 502 and 503 are obtained by heat-treating the coating film in the same manner as described above. Also, prior to applying the fluorine compound-containing liquid, the surface of the nozzle plate base material 501 may be pretreated in the same manner as described above.

Next, the nozzle plate 50 , the frame 40 and the piezoelectric member 30 are arranged so that the liquid-repellent film 503 faces the surface of the piezoelectric member 30 on which the electrode protective film 34 is provided, and the frame 40 is placed between the nozzle plate 50 and the piezoelectric member 30 . , and overlapped so that the nozzle N and the pressure chamber 32 communicate with each other. Then, it is heated, for example, at a temperature of 100° C. or higher and 200° C. or lower for 30 minutes or longer and 2 hours or shorter.

As a result, as shown in FIG. 4, the portions of the liquid-repellent film 503 and the electrode protection film 34 that are in contact with each other are integrated to form the fluorine compound layer 70 . Further, although not shown, portions of the adhesive layer provided on the main surfaces of the liquid-repellent film 503 and the frame 40 that contact each other are integrated to form a fluorine compound layer, which is provided on the main surfaces of the electrode protective film 34 and the frame 40 . The portions of the adhesive layers that are in contact with each other are integrated to form a fluorine compound layer. That is, it is thought that the ring structures shown in FIG. 5 positioned above and below so as to face each other are opened by heating, and then the ring-opened portions are joined together to form the ring structure shown in FIG. Thereby, the nozzle plate 50 is joined to the piezoelectric member 30 and the frame 40 .

The inkjet head 1 according to the embodiment can be manufactured by the above method. In this manufacturing method, the nozzle plate 50 can be attached to the actuator plate 20 without using conventional adhesives such as silane coupling agents, epoxy adhesives, and urethane adhesives.

Although the method of forming the coating film of the fluorine compound-containing liquid on the frame 40 has been described here, the application of the fluorine compound-containing liquid to the frame 40 may be omitted. A conventional adhesive may be used to bond the frame 40 to the actuator plate 20 and nozzle plate 50 .

2. Inkjet printer 2-1. Configuration FIG. 8 shows a schematic diagram of the inkjet printer 100 .
The inkjet printer 100 according to the embodiment includes inkjet heads 115C, 115M, 115Y and 115Bk, and a medium holding mechanism 110 that holds a recording medium facing the inkjet heads 115C, 115M, 115Y and 115Bk. Each of the inkjet heads 115C, 115M, 115Y and 115Bk is the inkjet head 1 described with reference to FIGS.

The inkjet printer 100 shown in FIG. 8 includes a housing in which a paper discharge tray 118 is provided. Cassettes 101a and 101b, paper feed rollers 102 and 103, transport roller pairs 104 and 105, registration roller pair 106, transport belt 107, fan 119, negative pressure chamber 111, transport roller pairs 112, 113 and 114, Inkjet heads 115C, 115M, 115Y and 115Bk, ink cartridges 116C, 116M, 116Y and 116Bk, and tubes 117C, 117M, 117Y and 117Bk are installed.

The cassettes 101a and 101b accommodate recording media P of different sizes. The paper feed roller 102 or 103 takes out the recording medium P corresponding to the size of the selected recording medium from the cassette 101a or 101b and conveys it to the conveying roller pairs 104 and 105 and the registration roller pair .

The transport belt 107 is tensioned by a driving roller 108 and two driven rollers 109 . Holes are provided at predetermined intervals on the surface of the transport belt 107 . A negative pressure chamber 111 connected to a fan 119 is installed inside the transport belt 107 to attract the recording medium P to the transport belt 107 . Conveying roller pairs 112 , 113 and 114 are installed downstream of the conveying belt 107 in the conveying direction. A heater for heating the print layer formed on the recording medium P can be installed on the transport path from the transport belt 107 to the discharge tray 118 .

Four inkjet heads for ejecting ink onto the recording medium P according to image data are arranged above the transport belt 107 . Specifically, an inkjet head 115C that ejects cyan (C) ink, an inkjet head 115M that ejects magenta (M) ink, an inkjet head 115Y that ejects yellow (Y) ink, and an inkjet head 115Y that ejects black (Bk) ink. The inkjet heads 115Bk are arranged in this order from the upstream side.

Above the inkjet heads 115C, 115M, 115Y and 115Bk are cyan (C) ink cartridges 116C, magenta (M) ink cartridges 116M, yellow (Y) ink cartridges 116Y and black ink cartridges 116C and 116M, respectively. (Bk) An ink cartridge 116Bk is installed. These ink cartridges 116C, 116M, 116Y and 116Bk are connected to inkjet heads 115C, 115M, 115Y and 115Bk by tubes 117C, 117M, 117Y and 117Bk, respectively.

Although not shown, the inkjet printer 100 may include heaters for heating the liquid-repellent films on the nozzle plates of the inkjet heads 115C, 115M, 115Y and 115Bk. When the liquid repellency of the liquid repellent film of the ink jet head is lowered, the liquid repellent property of the liquid repellent film can be recovered by reheating the liquid repellent film.

2-2. Image Formation Next, the image formation operation of the inkjet printer 100 will be described.
First, an image processing means (not shown) starts image processing for recording, generates an image signal corresponding to the image data, and generates a control signal for controlling the operation of various rollers, the negative pressure chamber 111, and the like. do.

The paper feeding rollers 102 or 103 take out the recording medium P of the selected size one by one from the cassette 101a or 101b under the control of the image processing means, and convey them to the conveying roller pairs 104 and 105 and the registration roller pair 106. do. The registration roller pair 106 corrects the skew of the recording medium P and conveys the recording medium P at a predetermined timing.

The negative pressure chamber 111 sucks air through holes in the conveyor belt 107 . Accordingly, the recording medium P is conveyed to positions below the inkjet heads 115C, 115M, 115Y and 115Bk in sequence as the conveying belt 107 moves while being attracted to the conveying belt 107 .

The inkjet heads 115C, 115M, 115Y and 115Bk eject ink in synchronization with the timing at which the recording medium P is conveyed under the control of the image processing means. Thus, a color image is formed at a desired position on the recording medium P. FIG.

Thereafter, conveying roller pairs 112 , 113 and 114 discharge the recording medium P on which the image is formed to a paper discharge tray 118 . When a heater is installed in the transport path from the transport belt 107 to the discharge tray 118, the print layer formed on the recording medium P may be heated by the heater. Heating by the heater can improve the adhesion of the print layer to the recording medium P, especially when the recording medium P is impermeable.

3. Effect Silane coupling agents, epoxy-based adhesives, urethane-based adhesives, and the like are sometimes used as adhesives for bonding the nozzle plate 50 and the piezoelectric member 30 . When these adhesives come into contact with the ink inside the pressure chamber 32, they may dissolve in the ink depending on the pH of the ink and the type of solvent. When the adhesive dissolves in the ink, the bondability between the nozzle plate 50 and the piezoelectric member 30 is lost, and the nozzle plate 50 may separate from the actuator plate 20 .

In the inkjet head 1 according to the embodiment, the fluorine compound layer 70 exists between the nozzle plate 50 and the piezoelectric member 30 . The fluorine compound layer 70 serves as an adhesive that bonds the nozzle plate 50 and the piezoelectric member 30 together. Since the fluorine compound layer 70 is a film containing a fluorine compound, it is excellent in water repellency and oil repellency, and also excellent in chemical resistance. Therefore, even if the fluorine compound layer 70 comes into contact with the ink inside the pressure chamber 32, it is difficult to dissolve in the ink. Therefore, this inkjet head 1 can stably eject ink over a long period of time. In addition, this inkjet head 1 can be applied to various inks including alkaline water-soluble inks that readily dissolve conventional adhesives, regardless of the pH of the ink or the type of solvent.

Further, the fluorine compound layer 70 can be debonded by ultraviolet (UV) irradiation and then rebonded by heating. This will be explained below.

The fluorine compound layer 70 joins the nozzle plate 50 to which the first layer 701 is bonded and the piezoelectric member 30 to which the second layer 702 is bonded by a third layer 703 having an annular structure shown in FIG. The annular structure of the third layer 703 can be cut, for example, by irradiating from the nozzle plate 50 side with UV light having a wavelength that cuts only CC bonds. As a result, the fluorine compound layer 70 is separated into two layers at the intermediate position, and the nozzle plate 50 and the piezoelectric member 30 can be separated. By heating the peeled nozzle plate 50 and the piezoelectric member 30 while they are in contact with each other, the cut annular structure is formed again, and the nozzle plate 50 and the piezoelectric member 30 can be rejoined.

That is, the fluorine compound layer 70 can reversibly bond and separate the nozzle plate 50 and the piezoelectric member 30 . Therefore, the inkjet head 1 can significantly reduce manufacturing defects due to misalignment of the joint position of the nozzle plate 50, for example.

Although the inkjet head 1 has been described above as an example, the bonding by the fluorine compound layer 70 can be used in a wide range of fields such as machinery, electricity, communication, and construction, regardless of the material and properties of the base material.

Examples are described below.
(Example 1)
The ink jet head 1 shown in FIGS. 1 to 4 was produced as follows.
First, a structure including piezoelectric members 30 and electrodes 33 was formed on the actuator plate 20 . PZT was used as the piezoelectric member 30 . Next, a fluorine compound-containing liquid was applied onto the electrode 33 by a spin coating method to form a coating film. This coating film was subjected to heat treatment at 180° C. for 30 minutes to obtain an electrode protective film 34 . CYTOP (registered trademark) A type manufactured by AGC Corporation was used as the fluorine compound-containing liquid.

Next, the fluorine compound-containing liquid was applied to both surfaces of the frame 40 by spin coating to form a coating film. This coating film was subjected to a heat treatment at 200° C. for 2 hours to provide an adhesive layer on both sides of the frame 40 . As shown in FIG. 2, a frame 40 was attached to the upper surface of the actuator plate 20 via an adhesive layer.

Next, both surfaces of the nozzle plate base material 501 were coated with the fluorine compound-containing liquid using a spin coating method to form a coating film. This coating film was subjected to heat treatment at 180° C. for 30 minutes to form liquid-repellent films 502 and 503 on both surfaces of the nozzle plate base material 501 . A polyimide film was used as the nozzle plate base material 501 .

The nozzle plate 50 , the frame 40 and the piezoelectric member 30 are arranged such that the liquid-repellent film 503 faces the surface of the piezoelectric member 30 on which the electrode protective film 34 is provided, and the frame 40 is interposed between the nozzle plate 50 and the piezoelectric member 30 . , so that the nozzle N and the pressure chamber 32 communicate with each other to obtain a laminate. This laminate was subjected to heat treatment at 200° C. for 2 hours to form the fluorine compound layer 70 and join the nozzle plate 50 and the actuator plate 20 together.

(Comparative example 1)
A film made of polyparaxylylene (parylene C) is used as the electrode protective film 34, an epoxy adhesive is used as the adhesive layer of the frame 40, and an epoxy adhesive is used instead of the liquid-repellent film 503. An inkjet head 1 was obtained in the same manner as in Example 1, except for the above.

(XPS analysis)
The XPS spectrum of the fluorine compound layer 70 of the inkjet head manufactured in Example 1 was measured by the method described above. The results are shown in FIG. The XPS spectrum of the second layer 702 was identical to the XPS spectrum of the first layer 701.

(Stability evaluation)
Using water-based ink, the stability of the inkjet heads of Examples and Comparative Examples was evaluated. Specifically, a tensile test was performed after the bonding portion was immersed in water-based ink for a long period of time.

As a result, the tensile test strength of the inkjet head of the example was greater than the tensile test strength of the inkjet head of the comparative example. That is, the stability of the inkjet head of the example was superior to that of the inkjet head of the comparative example.

Since the inkjet head according to at least one embodiment described above has at least the fluorine compound layer positioned between the piezoelectric member and the nozzle plate, excellent stability can be achieved.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

REFERENCE SIGNS LIST 1 inkjet head 10 ink manifold 11 ink supply pipe 12 ink return pipe 20 actuator plate 21 ink supply port 22 ink discharge port 30 piezoelectric member 31 wiring pattern 32 Pressure chamber 33 Electrode 34 Electrode protection film 40 Frame 50 Nozzle plate 60 Flexible printed circuit board 61 Drive circuit 70 Fluorine compound layer 100 Inkjet printer 101a Cassette 101b Cassette 102 Paper feed roller 103 Paper feed roller 104 Conveyance roller pair 105 Conveyance roller pair 106 Registration roller pair 107 Conveyor belt 108 Drive roller 109 Driven roller 110 Medium holding mechanism 111 Negative pressure chamber 112 Carrying roller pair 113 Carrying roller pair 114 Carrying roller pair 115Bk Inkjet head 115C Inkjet head 115M Inkjet head 115Y Inkjet head 116Bk Ink cartridge 116C...Ink cartridge 116M...Ink cartridge 116Y...Ink cartridge 117Bk...Tube 117C...Tube 117M...Tube 117Y...Tube 118...Discharge tray 119...Fan 301...First piezoelectric body , 302 Second piezoelectric body 501 Nozzle plate base material 502 Liquid-repellent film 503 Liquid-repellent film 701 First layer 702 Second layer 703 Third layer N Nozzle P …recoding media.

Claims (5)

a nozzle plate including nozzles for ejecting ink toward a recording medium;
a piezoelectric member that forms a pressure chamber at a position that communicates with the nozzle, and changes the pressure in the pressure chamber to eject the ink in the pressure chamber;
a fluorine compound layer positioned between at least the piezoelectric member and the nozzle plate;
The fluorine compound layer includes a first layer located on the nozzle plate side, a second layer located on the piezoelectric member side, and a third layer located between the first layer and the second layer. ,
The X-ray photoelectron spectroscopy spectra of the first to third layers each include a peak belonging to CF ₂ groups, and the peak area PA3 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the third layer is An inkjet head larger than the peak area PA1 of CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the layer and larger than the peak area PA2 of CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the second layer. The ratio PA3/PA1 between the peak area PA3 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the third layer and the peak area PA1 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the first layer, and , the ratio PA3/PA2 between the peak area PA3 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the third layer and the peak area PA2 of the CF ₂ groups contained in the X-ray photoelectron spectroscopy spectrum of the second layer is , 2 or more and 3 or less. 3. The inkjet head according to claim 1, wherein the X-ray photoelectron spectroscopy spectra of the first layer and the second layer each further include peaks belonging to _CF2O groups. an electrode positioned in a portion of the piezoelectric member adjacent to the pressure chamber and applying a driving pulse to the piezoelectric member;
4. The inkjet head according to any one of claims 1 to 3, further comprising an electrode protective film covering the electrodes and containing a fluorine compound. The inkjet head according to any one of claims 1 to 4;
and a medium holding mechanism that holds the recording medium facing the inkjet head.