JP3127570B2 - Method of manufacturing inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to a method for manufacturing an ink jet head for performing printing on paper or the like.

[0002]

2. Description of the Related Art Generally, a nozzle orifice of an ink-jet printer has a nozzle opening, that is, a diameter of an ink droplet ejection surface in a range of 30 μm to 80 μm. In the case of using a metal plate as a material, electroforming, press working, etching, electric discharge machining, and the like are known as methods conventionally used for performing such fine hole processing.

[0003] When a synthetic resin is used, injection molding, etching, or a method of forming a photosensitive resin is known. Japanese Patent Application Laid-Open No. 1-108056 discloses a processing method using an excimer laser.

[0004]

However, in the above-mentioned prior art, a nozzle profile which realizes a high-density nozzle row arrangement and satisfies the ink droplet flying characteristics cannot be obtained. These will be described.

[0005] Ink jet printers are widely used because of their high printing speed, excellent printing quality, and quietness. Accordingly, there is a demand for further improvement in print quality. In order to improve print quality, it is essential to increase the ejection density of ink droplets. In that case, the best means is to increase the arrangement density of the nozzles and the droplet generating means.

[0006] Increasing the arrangement density of the nozzle openings can be achieved by:
Conventional techniques are possible to some extent. However, in the conventional method, the high-density arrangement and the ink droplet flying stability have opposite characteristics. This is because the volume surrounded by the nozzle profile (hereinafter, abbreviated as the nozzle volume) decreases in order to increase the nozzle arrangement density. This will be described with reference to FIG.

FIG. 7 shows a main sectional view of an ink jet head using a conventional nozzle forming member. The conventional nozzle forming member 101 has a plurality of nozzle openings 111.
The pressure chamber 205 corresponds to the nozzle opening 111. The pressure generating element 208 is connected to the pressure chamber 205.

FIG. 7A shows a standby state. FIG. 7 (b)
In, the pressure generating element 208 is displaced by the drive signal, and the ink droplet 301 is ejected from the nozzle opening 111. FIG. 7C shows a state in which the pressure generating element 208 has returned to the standby state after the ejection of the ink droplet 301. Pressure chamber 20
Since the ink pressure of No. 5 decreases, the air bubble 401 is sucked from the nozzle opening 111 to form a meniscus. Thereafter, the ink is supplied gradually, and returns to the state shown in FIG.

The meniscus shown in FIG. 7C, which extends to the outside of the nozzle profile, is extremely unstable. Such a meniscus causes the generation of independent air bubbles in the pressure chamber and the problem of a decrease in the amount of flying droplets.

As described above, in order to stabilize the meniscus, a sufficiently large nozzle volume is required as compared with the amount of ink droplets that fly. In order to increase the arrangement density and obtain a sufficient nozzle volume, a nozzle profile having an oval cross section having a minor axis in the pitch direction is most suitable.

On the other hand, the nozzle opening is preferably a perfect circle in order to stabilize the flight direction of the ink droplet. This is to make the surface tension received from the circumference of the nozzle opening uniform in all directions.

From the above, the nozzle opening is a perfect circle,
It can be said that the nozzle orifice having an oval profile is the best means for obtaining excellent print quality.

The above-mentioned prior art can realize the above-mentioned nozzle orifice by electric discharge machining for a metal material, injection molding for a resin material, and JP-A-1-1080.
56, which uses an excimer laser.

However, in the electric discharge machining, the machining size is fine and the cutting tool used is greatly consumed. Similarly, injection molding cannot ensure precise mold accuracy over a long period of time.

In the method using an excimer laser disclosed in Japanese Patent Application Laid-Open No. 1-108056, it is necessary to give a precise swinging motion to a workpiece during laser irradiation in conjunction with a laser pulse. This indicates that the excimer laser irradiation surface is always inclined, and the absolute irradiation energy becomes non-uniform. For this reason, uniform processing is difficult.
Such a complicated process cannot be said to be an inexpensive and easy method of manufacturing a nozzle forming member.

[0016]

According to the present invention, there is provided an ink jet printer.
Method of manufacturing a head includes a nozzle forming member having a plurality of nozzles orifices, in the manufacturing method of the ink jet head and an ink droplet generating means corresponding to the nozzle orifice, the processing of the nozzle orifice, said Bruno
Performing a plurality of stop holes with a predetermined laser beam diameter around the through-hole forming portion on the side of the ink droplet generating means of the chirping member, and thereafter, forming the laser beam diameter in the through-hole forming portion;
In it and a step of performing through-hole machining, the blind hole machining, who orthogonal to the pitch direction of the nozzle orifice
A locking hole machining a plurality of times while sequentially moving the laser beam center toward said through-hole forming portion from a position apart from the through hole forming element in countercurrent.

[0017]

FIG. 1 is a conceptual view showing an example of a method for manufacturing a nozzle forming member using the present invention. The present invention will be described with reference to FIG.

The workpiece 40 used in this embodiment is a film made of polyimide and having a thickness of 0.1 mm.

The laser light oscillating device 1 is an excimer laser device. In this embodiment, KrF gas is used, and the wavelength 2
48 nm was emitted at 50 Hz. The laser light output portion 11 is a rectangle of 12 × 23 mm and outputs parallel light by surface emission. The size of the light emitting surface 11 is 12 mm in height × 23 mm in width.

The laser light is output from the light emitting surface 11 as parallel light. The light output from the light emitting surface 11 is focused by the mask 2 only on the optical path necessary for processing. afterwards,
The light is reduced and collected by the biconvex lens 3, and is irradiated on the workpiece.

The configuration of the present embodiment will be described in more detail.
The mask 2 is manufactured by electric discharge machining using a plate of titanium-copper alloy having a thickness of 0.1 mm. The reason why the titanium-copper alloy is selected as the material is that it has good thermal conductivity and can withstand long-term irradiation with laser light. 0.4 for mask 2
There is a pattern 21 of a perfect circle of mm, from which the laser light passes.

A biconvex lens 3 having a focal length of 75.6 mm is placed 840 mm away from the mask 2. The focal plane is calculated by the following equation.

75.6 × 840 / (840-75.6)
≒ 83 (unit: mm) That is, the laser beam is focused at a position about 83 mm away from the lens 3. Also, a distance A between the mask 2 and the lens 3;
The reduction ratio can be calculated from the ratio of the distance B between the lens 3 and the workpiece 40.

83/840 ≒ 0.1 Therefore, the image of the image of the mask 2 formed by the image of the
It is 1 time, and becomes φ0.04 mm. This is the area processed by the laser light.

The processing procedure will be described with reference to the drawings. FIG. 2 shows the workpiece 40 in FIG. 1, and FIG. 3 shows the workpiece position 41 in FIG.

First, in FIG. 2, a laser beam is applied to a position 30 μm away from the center line 51 of the nozzle opening at a center-to-center distance. In this embodiment, the speed at which the polyimide film as the workpiece 40 is processed is 0.6 μ per pulse. Therefore, a stop hole 52 having a depth of 12 μ is formed by irradiation of 20 pulses.

Subsequently, in FIG. 3, from the position of FIG.
The workpiece is moved toward the center line 51 of the nozzle opening by a distance of 5 μm, and the laser beam is again irradiated with 20 pulses. The portion 53 overlapping with the processing point in FIG. 2 is a double depth 24 μm.
Processed.

The above operation is counted by the number of laser irradiations.
Repeat 6 times. Thereafter, the same processing is performed on the opposite side of the center line 51. This forms a step-like profile. Taking into account the overlapping part by processing from both sides, the deepest point is (6 times + 1) × 12μ = 84μ.

Finally, the laser beam is irradiated to the nozzle opening center line 51 at 200 pulses. A through hole is formed by this processing, and a nozzle opening is obtained.

By the above processing, one nozzle orifice can be formed. This nozzle orifice has a profile in which the nozzle opening is a perfect circle having a diameter of 0.04 mm and spreads stepwise only in one axial direction. On the widest ink supply side, width 0.04 mm, length 0.1 mm,
It is an ellipse of R0.02 mm.

By processing such a nozzle orifice at a plurality of locations, the nozzle forming member 110 shown in FIG. 4 is manufactured. If the short-diameter direction of the nozzle orifice matches the pitch direction, the nozzle orifice can be arranged at the highest density. In the present embodiment, the pitch of the nozzle orifices is 180 dpi, that is, 141 μ.

FIG. 5 shows a conceptual diagram of an example of an ink jet head using the nozzle forming member. The pressure generating element 208 is fixed to the fixing plate 209. In this embodiment, a laminated piezoelectric element is used as the pressure generating element.

The tip of the pressure generating element 208 is
02 is attached to the diaphragm 204. Flow path substrate 202
The nozzle forming member 110 is joined to the thick portion 212 of the nozzle. The ink is guided from the ink tank to the flow path 207 of the flow path substrate 202 through the pipe 255, passes through the supply port 206, and is filled between the vibration plate 204 and the nozzle forming member 110.

When a drive signal is given by the drive circuit 220, the pressure generating element 208 vibrates the diaphragm 204 to increase the ink pressure. Thereby, the nozzle opening 1
00, ink droplets are ejected.

The ink droplet to be ejected is 0.08 μcc
It is. The calculated nozzle volume of the nozzle forming member in FIG. 2 is about 0.3 μcc.

Since the ink-jet head using the nozzle forming member of the present invention has a large nozzle volume, the meniscus of the ink liquid after ink discharge is stable, and no bubbles are drawn. For this reason, it has become possible to obtain more stable flight characteristics than before.

As shown in FIG. 4, the nozzle orifice of the nozzle forming member manufactured according to the present embodiment has a width of 5 μm and a step height of 12 μm.
μ stepwise profile, finally connected to a straight nozzle opening. The step-like profile can be easily changed by changing the moving distance of the workpiece. The step can also be easily adjusted by changing the number of irradiation pulses. That is, by increasing the number of divisions, a smoother nozzle profile can be obtained.

Further, in this embodiment, the direction in which one nozzle orifice moves by 5 μm is limited to the uniaxial direction. However, by setting this direction to the biaxial direction, the nozzle volume can be further reduced. Large nozzle orifices can be manufactured.

FIG. 6 is a main sectional view of a nozzle forming member 110 according to another embodiment using the present invention. The processing apparatus uses the optical system shown in FIG. The material is 0.125 mm thick polyetherimide film.
It was used.

As shown in FIG. 6, the nozzle profile has a horn shape only in the major axis direction of the ellipse on the inlet side. However, it has a straight profile in the minor axis direction. As described above, according to the present invention, a shape in which the nozzle profile shows a curved change can be easily processed.

In order to form such a profile, the position and the number of irradiation pulses are obtained from the following equation and processed.

With the intersection of the center line of the nozzle orifice and the ink inlet side surface of the nozzle forming member as the origin, the x-axis is taken in the direction of the nozzle opening along the center line, and the y-axis is taken in the major axis direction. ) ² + (y + t) ² = t ² where t is the thickness of the nozzle forming member, and a is the nozzle opening radius. In this embodiment, t = 0.125 mm a = 0.02 mm.

In Equation 1, the value of x indicates the distance over which the workpiece is moved. Further, the value of y represents the processing depth. Therefore, to calculate the number of irradiation pulses p from the value of y, y
May be divided by the processing speed per pulse. In this example, as a result of the actual measurement, the processing speed of the polyetherimide was 1
0.6 μ per pulse.

The nozzle volume of the nozzle orifice of FIG. 6 is about 0.3 μcc. This nozzle forming member was again used for the ink jet head shown in FIG. In this ink jet head, a stable flight of ink droplets was obtained as in the above-described embodiment.

[0045]

As described above, according to the present invention, in a method for manufacturing an ink jet head comprising a nozzle forming member having a plurality of nozzle orifices and ink droplet generating means corresponding to the nozzle orifices, The processing of the nozzle orifice is based on the ink of the nozzle forming member.
Predetermined laser light around the through hole forming part on the droplet generation means side
And performing a plurality of times stop drilling in diameter, a step of subsequently performing through-hole machining by the laser beam diameter in the through hole forming portion
And the stop hole processing is performed on the nozzle orifice.
The laser light is directed toward the through-hole forming portion from a position away from the through-hole forming portion in a direction orthogonal to the pitch direction.
It is a stop hole processing that is performed multiple times while sequentially moving the heart
Thus, a nozzle forming member in which the nozzles are arranged at a high density can be formed by a simple method without reducing the nozzle volume. Further, the nozzle profile can be selected from an arbitrary curve. Further, all of the stop holes
By forming the body to be an ellipse having a minor axis in the pitch direction of the nozzle orifice, a sufficient nozzle volume can be obtained while increasing the nozzle arrangement density, and the meniscus can be stabilized.

Since the manufactured nozzle forming member has a large nozzle volume, the meniscus behavior of the ink liquid is stabilized. Therefore, there is an effect that an ink jet printer with stable ink droplet flight can be obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an example of a method for manufacturing a nozzle forming member of the present invention.

FIG. 2 is a perspective view including a cross section of the nozzle forming member according to the embodiment of the present invention during processing of the nozzle forming member.

FIG. 3 is a perspective view, including a cross section, showing a partway through the processing of the nozzle forming member according to the embodiment of the present invention.

FIG. 4 is a perspective view including a cross section of a nozzle forming member manufactured according to an embodiment of the present invention.

FIG. 5 is a main cross-sectional view of the inkjet head.

FIG. 6 is a perspective view including a cross section of a nozzle forming member manufactured according to another embodiment of the present invention.

FIG. 7 is a main cross-sectional view of an ink jet head using a nozzle forming member manufactured by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excimer laser apparatus 11 Laser light output surface 2 Mask 21 Mask pattern 3 Biconvex lens 40 Workpiece 41 Workpiece position during processing 51 Nozzle opening center line 52 Stop hole processing part 53 Overlapping part of stop hole processing 100 Nozzle opening 101 by the manufacturing method of the present invention 101 Nozzle forming member by the conventional manufacturing method 110 Nozzle forming member by the manufacturing method of the present invention 111 Nozzle opening by the conventional manufacturing method 202 Flow path substrate 204 Vibrating plate 205 Pressure chamber 206 Ink supply port 207 Ink flow path 208 Pressure generating element 209 Fixing plate 210 Case 212 Thick part of flow path substrate 220 Pressure generating element driving circuit 255 Ink supply pipe 301 Ink droplet 401 Air bubble

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-277554 (JP, A) JP-A-57-178768 (JP, A) JP-A-1-108056 (JP, A) JP-A-2- 241685 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/135 B23K 26/00 330

Claims (3)

(57) [Claims] 1. A nozzle forming member having a plurality of nozzles orifices, in the manufacturing method of the ink jet head and an ink droplet generating means corresponding to the nozzle orifice, the processing of the nozzle orifice, said nozzle forming member
A predetermined area around the through hole forming portion on the ink droplet generating means side
Steps of drilling multiple holes with laser beam diameter, and then
Consists of a step of performing through-hole machining by the laser beam diameter in the through hole forming portion, the stop drilling, the Nozuruo
Les from a position apart from the through hole forming element in a direction perpendicular to the pitch direction of the orifice toward said through-hole forming portion
Stop hole processing performed multiple times while sequentially moving the laser light center
A method for manufacturing an ink jet head. 2. The nozzle orifice according to claim 2, wherein said stopper hole is entirely formed in said nozzle orifice.
The method for manufacturing an ink-jet head according to claim 1, wherein the ink-jet head is formed to have an elliptical shape having a minor axis in a pitch direction of the ink jet head. Wherein the laser method according to claim 1 or 2 inkjet head according an excimer laser.