JPH1110874A - Ink jet recording head for ultraviolet curable ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eject ink containing an ultraviolet curing agent or an organic agent as ink drops without creating clogging. SOLUTION: This recording head comprises an elastic plate deformed by the deformation of a piezoelectric vibrator, a fluid passage forming substrate that forms a pressure generating chamber for receiving ink from an ink reservoir via an ink supply hole and a nozzle plate 10 having a nozzle opening 11 which is communicated to the pressure generating chamber to eject ink drops. The nozzle plate 10 having a light shading property comprises an eutectoid plating layer 28 having ink repellency in the vicinity of the nozzle opening. As a result, the ink K moves back to the innermost portion of the pressure generating chamber by virtue of the repellency of the eutectoid plating layer 28 in a condition that the ink drops are not ejected and ultraviolet rays are shaded by the nozzle plate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head suitable for printing on a printed circuit board or the like with special ink.

[0002]

2. Description of the Related Art In a printed circuit board, a shape, a character, and the like are printed for the purpose of clarifying an arrangement position of a component and a type of the component. For such printing,
A method of screen-printing an ink having an insulating property using a screen in which a pattern is previously formed as a window is used. However, a circuit board on which high-density mounting is performed has a problem that positioning is difficult, and a new screen needs to be manufactured every time a design change or the like is performed.

In order to solve such a problem, a piezoelectric vibrator is used which does not needlessly heat a liquid as in a bubble jet type recording head, and which can relatively freely adjust a discharge pressure by an electric signal. The colored liquid is ejected as droplets by the inkjet recording head,
2. Description of the Related Art Devices for drawing patterns and characters on an object to be coated such as a printed circuit board have been put to practical use. According to this, since character data and pattern data are extracted from the printed circuit design data, and characters and patterns can be printed only by discharging a colored liquid based on the data, it is not necessary to manufacture a printing screen. There is an advantage that design changes can be flexibly dealt with.

[0004]

On the other hand, on the other hand, the ink used for such a purpose is a pigment which has electrical insulation properties and does not corrode the printed wiring pattern, for example, titanium oxide is used. Since it contains an ultraviolet curing agent for the purpose of improvement, there is a problem that unlike ink used for recording on pulp or the like, clogging of an ink jet recording head is liable to occur. In order to alleviate such a problem, it has been proposed to add an aliphatic polyhydric alcohol such as glycerin to an ultraviolet curable ink as disclosed in, for example, JP-A-8-48922. According to this, the time until clogging can be extended, but there is a problem that irreversible clogging occurs when ultraviolet rays are irradiated near the nozzle opening, because the curing is basically performed by ultraviolet rays. .

The present invention has been made in view of such a problem, and an object of the present invention is to provide an inkjet recording method suitable for an ultraviolet curable ink which can prevent clogging of the ultraviolet curable ink. Is to provide a head. Another object of the present invention is to provide an ink jet recording head suitable for an ultraviolet curable ink which has durability against an organic agent contained in the ink.

[0006]

According to the present invention, there is provided an elastic plate which is deformed by displacement of a piezoelectric vibrator, and supplies ink from an ink reservoir through an ink supply port. A flow path forming substrate forming a receiving pressure generating chamber, and a nozzle plate provided with a nozzle opening for discharging ink droplets in communication with the pressure generating chamber,
The nozzle plate has a light-shielding property and has a water-repellent eutectoid plating layer near the nozzle opening.

[0007]

In the non-ink drop ejection state, the ink retreats to the interior of the pressure generating chamber due to the water repellency of the eutectoid plating layer, and the ultraviolet light is blocked by the nozzle plate. Curing of the ink due to the ultraviolet rays is prevented.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an embodiment of a printed circuit board printing apparatus, in which a carriage 1 on which an ink jet recording head described later is mounted.
Is reciprocally movable in the direction of arrow A by a drive motor (not shown) housed in the mechanism chamber 3 of the frame 2, and the ink cartridge 5
Is supplied to the ink jet recording head.

Below the frame 2, a stage 6 for supporting the printing material P is provided on both sides of a guide member 8 of a base 7 so as to face a nozzle opening of an ink jet type recording head. (In the direction indicated by).

2 and 3 show an embodiment of the above-mentioned ink jet recording head. In the drawings, reference numeral 10 denotes a nozzle plate having nozzle openings 11, 11, 11,. The flow path forming plates 13 are elastic plates, and both sides of the flow path forming plate 12 are sealed with the nozzle plate 10 and the elastic plate 13 to form the ink flow path unit 14.

The nozzle plate 10, the flow path forming substrate 12, and the elastic plate 13 are made of a material having corrosion resistance to an organic solvent component contained in the ultraviolet curable ink, for example, metal, single crystal silicon, fine ceramic, or the like. It consists of.

The ink flow path unit 14 is configured such that a recess or a through hole formed in the flow path forming plate 12 is
0, and the other surface is sealed with an elastic plate 13 so that the pressure generating chamber 15 communicating with the nozzle opening 11 and the ink reservoir 1
6, and an ink supply port 17 for connecting the pressure generating chamber 15 and the ink reservoir 16 are formed. The ink supply port 17 is accommodated in the head holder 19 so as to receive the extension displacement and the contraction displacement of the piezoelectric vibrator 20 described later on the elastic plate 13. I have.

The piezoelectric vibrator 20 is formed by alternately laminating a piezoelectric material 21, an internal electrode serving as one pole, and conductive materials 22 and 23 forming an internal electrode serving as the other pole in parallel with the direction of extension. Is configured as a vibrator in a so-called longitudinal vibration mode, which contracts and expands at the time of transition from the charged state to the discharged state, with the distal end being in contact with the elastic plate 13 so as to face the pressure generating chamber 15 and the like. The end is fixed to the base 24. In the drawing, reference numeral 25 denotes an ink introduction tube for supplying ink to the ink reservoir 16 by the ink supply tube 4, reference numeral 26 denotes a frame serving also as a shield case for fixing the flow path unit 14 to the head holder 19, and Reference numeral 27 denotes a flexible cable that supplies a drive signal to the piezoelectric vibrator 20.

The nozzle plate 10 is made of a material which is opaque to ultraviolet rays, for example, a metal. As shown in FIG. 4A, the nozzle plate 10 extends straight from the ink discharge side surface 10a of the nozzle plate 11 to the nozzle opening 11 as shown in FIG. Part 11
a, a eutectoid plating layer 28 of a fluoropolymer is formed in a region extending to the tapered portion 11b.

The eutectoid plating layer 28 is formed by forming a base of nickel, a nickel-cobalt alloy, a nickel-phosphorus alloy, or a nickel-boric acid alloy on the surface of the metal constituting the nozzle plate body, and then forming a fluorine-based resin such as polytetrafluoroethylene. , Polyfluoroalkylbutadiene,
Immerse polyfluorovinylidene, polyfluorovinyl, polydiperfluoroalkyl fumarate alone or in a mixed electrolytic solution, apply an electric field, pull it up after a predetermined time, and heat it at a temperature of about 350 ° C. Is formed.

As a result, the fluororesin uniformly adheres to the surface of the nozzle plate 10 using nickel ions as a medium to form a smooth, hard, and ink-repellent layer near the nozzle opening 11.

In this embodiment, the ink supply tube 4
When the ultraviolet curable ink is supplied from the ink cartridge 5 to the ink reservoir 16 of the recording head and print data is output from the host, the piezoelectric vibrator 20 contracts to expand the pressure generating chamber 15, and the ink in the ink reservoir 16 Flows into the pressure generating chamber 15 through the ink supply port 17.

Then, when the drive signal to the piezoelectric vibrator 20 is cut off, the pressure generating chamber 15 is contracted in the process of expanding and returning to the original state, and the pressure generating chamber 15 is cured by an ultraviolet curing type. Pressurize the ink. As a result, ink droplets are ejected from the nozzle openings 11 and fly toward the printed circuit board P to form dots corresponding to the print data on the printed circuit board P. Needless to say, since the heating and vaporization for generating the pressure are not required for discharging the ink droplets unlike the valve jet, there is no possibility that the ultraviolet curable ink is deteriorated.

When the ink jet recording head has completed printing for one scan, the operation of moving the stage 6 by the print width of the recording head and printing the next area is repeated.

The ink droplets adhering to the printed circuit board P are cured by the irradiation of ultraviolet light from an unillustrated ultraviolet light source, and become a printed matter having frictional resistance. As described above, during printing, the ink near the nozzle openings is sequentially discharged as ink droplets, and therefore cannot be cured at the nozzle openings 11 even if irradiated with ultraviolet rays.

When printing is completed, the meniscus M of the ink located in the vicinity of the nozzle opening 11 is displaced by the water repellency of the eutectoid plating layer 25 formed in the nozzle opening 11 as shown in FIG. And the ultraviolet light is blocked by the nozzle plate, so that the amount of ultraviolet light received by the ink in the vicinity of the nozzle opening and the ink K in the pressure generating chamber 15 is extremely small, so that curing by ultraviolet rays does not occur. , The time to clogging is greatly extended.

Further, since the member constituting the flow path unit which is in direct contact with the ink is made of metal,
It is not affected by the solvent and the like in the ink and shows high durability.

In the above-described embodiment, a piezoelectric vibrator having a piezoelectric constant d31 is used. However, as shown in FIG. It is apparent that the same effect is obtained even when the piezoelectric vibrators having the piezoelectric constant d33 alternately stacked are used.

FIGS. 6 and 7 show a second embodiment of an ink jet type recording head which can be used in the above-mentioned apparatus. In the drawing, reference numeral 10 denotes a nozzle plate having a nozzle opening 11 formed therein. Is an ink reservoir forming substrate, 31
Denotes an ink supply port forming substrate, which forms the ink supply unit 32.

As described above, the nozzle plate 10 is provided with a fluorine-based polymer in a region extending from the surface 10a on the ink ejection side to the straight portion 11a and the tapered portion 11b of the nozzle opening 11 as shown in FIG. The eutectoid plating layer 28 is formed.

The ink reservoir forming substrate 30 is provided with ink reservoirs 34 and 34 for receiving ink supply from the ink guide port 33 of the ink supply port forming substrate 31 and nozzle communication holes 35 and 35 connected to the nozzle openings 11. ing.

The ink supply port forming substrate 31 also serves as a fixed substrate for an actuator unit 38 described later, and has ink reservoirs 34, 34 at one end on the pressure generating chamber side.
Ink supply ports 36, 36 connecting the pressure generating chamber and the pressure generating chamber,
Nozzle communication holes 37, 37 for communicating the other end side of the pressure generating chamber with the nozzle openings 11, 11;
3 is provided.

On the other hand, the actuator unit 38 includes a first lid member 39, a piezoelectric vibrator 40 which is flexibly displaced,
A spacer 42 that partitions the pressure generating chamber 41 and a second lid member 43 are stacked. These members 39,
40, 42, and 43 are integrally formed without using an adhesive by forming a ceramic material into a predetermined shape, laminating and firing.

The first cover member 39 is made of a thin plate of zirconia having a thickness of about 10 μm, has a common electrode 44 formed on one surface thereof as one pole, and has a pressure generating chamber 4 formed on the surface thereof.
The piezoelectric vibrators 40 and 40 are fixed so as to face the first and the first 41, respectively.

The spacer 42 is formed by piercing a through hole in a ceramic plate made of zirconia (ZrO 2) having a thickness suitable for forming the pressure generating chambers 41, for example, 150 μm, and a second lid member. Reference numeral 43 designates ink supply ports 36 and 36 and a pressure generating chamber 4 on a ceramic plate made of zirconia or the like.
1, 41, and the nozzle openings 11, 11 and the pressure generating chamber 4
Communication holes 44, 4 for communicating with the other ends of 1, 41 respectively
4, 45 and 45 are provided.

The actuator unit 38 and the flow path unit 32 are integrally fixed to each other by an adhesive means having durability against ink to constitute an ink jet recording head.

In this embodiment, the ink supply tube 4
Supplies the ultraviolet curable ink from the ink cartridge 5 to the ink reservoirs 34, 34 of the recording head, and outputs print data from the host. When the print data is output from the host, the pressure generating chamber 41 is expanded by the piezoelectric vibrator 40, and the ink reservoirs 34, 3,
The ink No. 4 flows into the pressure generating chambers 41, 41 via the ink supply ports 36, 36.

Next, when the drive signal to the piezoelectric vibrator 20 is cut off, the displacement of the piezoelectric vibrator 40 causes the pressure generating chamber 41,
41 is shrunk and the ultraviolet curable ink is
The ink droplets are ejected as ink droplets, and fly toward the printed circuit board P to form dots corresponding to the print data on the printed circuit board P. As described above, during printing, the ink near the nozzle openings is sequentially discharged as ink droplets, and therefore cannot be cured at the nozzle openings 11 even if irradiated with ultraviolet rays.

When the printing is completed, the meniscus M of the ink retreats to the inner side of the pressure generating chamber 41 due to the water repellency of the eutectoid plating layer 25 and the ultraviolet light is blocked by the nozzle plate 10 as described above. , The time to clogging is greatly extended.

The channel unit 3 which comes into direct contact with the ink
Since the members constituting the actuator unit 2 and the actuator unit 38 are made of ceramic or metal, they are not affected by the solvent or the like in the ink and exhibit high durability.

FIGS. 8 and 9 show a third embodiment of an ink jet type recording head which can be used in the above-described apparatus. In the drawing, reference numeral 10 denotes a nozzle plate having a nozzle opening 11 formed therein. Is a substrate for forming an ink pressure generation chamber, and a recording head is formed by sealing the opening of the substrate 50 for forming the ink pressure generation with the nozzle plate 10.

As shown in FIG. 4A, the nozzle plate 10 has a fluorine-based polymer in a region extending from the ink ejection side surface 10a to the straight portion 11a and the tapered portion 11b of the nozzle opening 11, as shown in FIG. The eutectoid plating layer 28 is formed.

The ink pressure generating chamber forming substrate 50 is formed by etching a silicon single crystal substrate so as to form one surface as an opening surface 51 and form a substrate 52 which is elastically deformed on the back surface, preferably a membrane portion made of silicon oxide. A pressure generating chamber 53, an ink reservoir 54 for supplying ink to the pressure generating chamber 53, and an ink supply port 55 for communicating the pressure generating chamber 53 and the ink reservoir 54 with a constant fluid resistance are formed. .

The nozzle plate 1 is connected to the opening surface 51 such that the nozzle opening 11 communicates with one end of the pressure generating chamber 53.
And a piezoelectric vibrating element 56 made of a piezoelectric film formed by a film forming method on the rear substrate 52.
Are formed in a region facing the pressure generating chamber 52.

The piezoelectric vibrating element 56 is formed by repeatedly applying and drying a PZT-based piezoelectric film precursor material obtained by mixing lead titanate and lead zirconate to a thickness of 1 μm by a sol-gel method. 3 at 650 ° C in atmosphere
And then heating at 900 ° C. for 1 minute.

In the drawing, reference numeral 57 denotes an ink guide port formed on the substrate 52 side of the ink pressure generating chamber substrate 50, reference numeral 58 denotes a flexible cable for supplying a drive signal for the piezoelectric vibrating element 56, and further reference numeral. Reference numeral 59 denotes a head holder.

In this embodiment, the ultraviolet curable ink is supplied from the ink cartridge 5 to the ink reservoir 54 of the recording head by the ink supply tube 4 through the ink supply tube 4 and the print data is output from the host. The pressure generating chamber 52 is expanded, and the ink in the ink reservoir 54 flows into the pressure generating chamber 52 via the ink supply port 55.

When the driving signal to the piezoelectric vibrating element 56 is cut off, the displacement of the piezoelectric vibrator 56 causes the pressure generating chamber 52 to move.
Is contracted, and the ultraviolet curable ink is ejected from the nozzle openings 11 as ink droplets, flies toward the printed circuit board P, and forms dots corresponding to the print data on the printed circuit board P.

When the printing is completed, the meniscus M of the ink retreats to the inner side of the pressure generating chamber 52 due to the water repellency of the eutectoid plating layer 25 and the ultraviolet light is blocked by the nozzle plate 10 as described above. , The time to clogging is greatly extended.

Since the members constituting the flow path unit which is in direct contact with the ink are made of a silicon single crystal substrate, silicon oxide, metal or the like, they are not affected by the solvent in the ink. Shows high durability.

[0046]

As described above, according to the present invention, the elastic plate which is deformed by the displacement of the piezoelectric vibrator and the pressure generating chamber which receives the supply of ink from the ink reservoir through the ink supply port are formed. A flow path forming substrate and a nozzle plate having a nozzle opening communicating with the pressure generating chamber and ejecting ink droplets. The nozzle plate has a light-shielding property, and ink-repellent eutectoid plating near the nozzle opening. In the non-ink droplet ejection state, the ink retreats to the back of the pressure generating chamber due to the water repellency of the eutectoid plating layer, and the ultraviolet light can be blocked by the nozzle plate, and the nozzle opening and the flow path forming substrate Curing of the ink due to the ultraviolet rays can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a printing apparatus to which an ink jet recording head of the present invention is applied.

FIG. 2 is an assembled perspective view showing an embodiment of the ink jet recording head of the present invention.

FIG. 3 is a diagram showing a cross-sectional structure of the recording head.

FIGS. 4A and 4B are a cross-sectional view showing an example of a nozzle plate of the recording head in an enlarged manner in the vicinity of a nozzle opening, and a diagram showing a state of a meniscus in a non-printing state. It is.

FIG. 5 is a diagram showing another embodiment of the piezoelectric vibrator applicable to the recording head.

FIG. 6 is an assembled perspective view showing another embodiment of the ink jet recording head of the present invention.

FIG. 7 is a diagram showing a cross-sectional structure of the recording head.

FIG. 8 is an assembled perspective view showing another embodiment of the ink jet recording head of the present invention.

FIG. 9 is a diagram showing a cross-sectional structure of the recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 4 Ink supply tube 5 Ink cartridge 6 Stage for mounting printed material 10 Nozzle plate 11 Nozzle opening 14 Flow path unit 20 Piezoelectric vibrator 28 Eutectoid plating layer for ink repellency 32 Flow path unit 38 Actuator unit 40 Piezoelectric vibrator M Meniscus K Ink

Claims (11)

[Claims] An elastic plate that is deformed by receiving a displacement of a piezoelectric vibrator; a flow path forming substrate that forms a pressure generating chamber that receives supply of ink from an ink reservoir via an ink supply port;
A nozzle plate having a nozzle opening communicating with the pressure generating chamber and discharging ink droplets, wherein the nozzle plate has a light-shielding property and has an ink-repellent eutectoid plating layer near the nozzle opening. Ink jet recording head for curable ink. 2. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein the eutectoid plating is a fluororesin. 3. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein the elastic plate, the flow path forming substrate, and the nozzle plate are made of a non-organic material. 4. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein said flow path forming substrate is formed of a silicon single crystal substrate. 5. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein said flow path forming substrate is made of ceramic. 6. The ink jet recording head according to claim 1, wherein the elastic plate is made of metal. 7. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein said elastic plate is made of silicon oxide. 8. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein the piezoelectric vibrator expands and contracts in the axial direction. 9. The ink jet recording head for ultraviolet curable ink according to claim 1, wherein the piezoelectric vibrator is displaced. 10. The ink jet recording head for ultraviolet curable ink according to claim 9, wherein the piezoelectric vibrator is formed by firing a thin plate of a piezoelectric material. 11. The ink jet recording head for ultraviolet curable ink according to claim 9, wherein said piezoelectric vibrator is formed by forming a film of a piezoelectric material.