JP2001187453A - Nozzle plate for piezoelectric driving type ink-jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle plate suitable for a piezoelectric driving type ink-jet recording head for realizing the stable ink droplet ejection. SOLUTION: A part of an ink repellent covering layer 2, covering the surface of a nozzle plate 1, is provided inside the nozzle such that the void capacity inside the nozzle from the nozzle plate 1 surface to the meniscus formation surface can be in a range from 0.05 to 0.50 with respect to the ink amount of ink droplets ejected at one time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle plate of an ink jet recording head for discharging ink droplets by a piezo driving element.

[0002]

2. Description of the Related Art In an ink jet recording head of a type in which a recording image is written on a recording medium by ink droplets ejected from a nozzle, the ink droplet flies due to the state around the nozzle, that is, the wetting of the ink around the nozzle. There is a problem such as deviation in the direction.

To solve such a problem, Japanese Patent Laid-Open Publication No.
No. 7848 discloses a nozzle plate in which an ink-repellent film such as a fluororesin is uniformly formed on the inner surface of the nozzle and the surface of the nozzle plate by sputtering to suppress the wetting of the ink around the nozzle. is there.

This method has an advantage that the ink droplets can be stably fly in the axial direction of the nozzle because the ink is prevented from wetting around the nozzle. However, in the method of forming the ink-repellent film, the amount of the ink-repellent film entering the inner surface of the nozzle is not constant. If the amount of the ink-repellent film is too large, the center of vibration of the meniscus moves away from the surface of the nozzle plate. However, the energy required to discharge the required amount of ink increases, the discharge efficiency deteriorates, and if the amount of penetration is too small, the center of vibration of the meniscus becomes closer to the surface of the nozzle plate,
There is a problem in that the ink droplets are re-discharged due to the vibration of the meniscus after the ink droplets are discharged, so-called misfire is caused. Japanese Patent Application Laid-Open No. 63-122560 discloses that an ink-repellent layer is formed by slightly penetrating the inside of a nozzle opening from the surface of a nozzle plate, but there is a problem with a piezo drive type ink jet recording head. There is no disclosure of a configuration required to maintain the optimum meniscus, that is, the amount of the ink-repellent layer entering the nozzle openings.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem.
An object of the present invention is to provide a nozzle plate suitable for a piezo-drive type ink jet recording head that realizes stable ejection of ink droplets by suppressing the amount of an ink-repellent substance entering the inner surface of a nozzle within a certain range.

[0006]

That is, according to the present invention, as a nozzle plate of an ink-jet printer for achieving the above object, a one-shot nozzle in which a void volume in a nozzle from a surface of a nozzle plate to a meniscus forming surface is discharged. A part of the ink-repellent coating layer covering the surface of the nozzle plate is made to enter the inner surface of the nozzle so that the ink amount of the ink droplet is in the range of 0.05 to 0.50.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an embodiment of a nozzle plate according to the present invention in terms of a surface treatment step.
FIG. 3 shows the nozzle plate formed by this step.

The nozzle plate indicated by reference numeral 1 in FIGS. 1 to 3 is formed of metal, ceramics, silicon, glass, plastic, or the like, and is preferably titanium, chromium, iron, cobalt, nickel, copper, zinc, tin, or the like. Single materials such as gold, or alloys such as nickel-phosphorus alloy, tin-copper-phosphorus alloy (phosphor bronze), copper-zinc alloy, stainless steel, polycarbonate, pristine, ABS resin (acrylonitrile / butadiene / styrene) Polymerization), polyethylene terephthalate, polyacetal, and various photosensitive resin materials. The nozzle plate 1 has a funnel-shaped portion 4 that is largely open on the back surface 3 side.
a, and a plurality of nozzle holes 4 comprising an orifice portion 4b which is open in a cylindrical shape on the front surface 2 side.

On the back surface 2 of the nozzle plate 1, first, a photosensitive resin film 5 which is cured by light, for example, a dry film resist of Dialon FRA305-38 (trade name) manufactured by Mitsubishi Rayon Co., Ltd. is laminated. The conductive resin film 5 is heated at a temperature of about 40 to 70 ° C. while applying a pressure of 4.0 kgf / cm 2, and a part of the film 5 is placed inside the nozzle 5 to a depth of 5 to 40 μm from the surface. (FIG. 1 (a)).

Next, ultraviolet rays are irradiated from the back surface 3 and the front surface 2 of the nozzle plate 1 to cure the entire photosensitive resin film 5 that has entered the back surface 3 of the nozzle plate 1 and the nozzles 4 (FIG. )).

This step is regarded as a pretreatment step for regulating the amount d of the eutectoid plating layer 6 to enter the nozzle 4 in the next eutectoid plating layer forming step.

Since the viscosity of the photosensitive resin material used for controlling the amount d of the plating layer 6 generally changes greatly depending on the temperature, the photosensitive resin film 5 reaches the required amount d of the plating layer. Part of nozzle 4
It is better to keep the applied pressure constant and to control the temperature t applied to the photosensitive resin film 5, that is, the amount of heating, in order to allow the photosensitive resin film 5 to enter the inside.

In this embodiment, a general nozzle plate, that is, a plate thickness T of 80 μm, a nozzle diameter D of 40 μm,
Nozzle plate 1 in which the length 1 of the cylindrical portion of the nozzle is 35 μm
A photosensitive resin film 5 having a thickness of 38 .mu.m is adhered to the back surface 3, and 4.0 kgf / cm @ 2 and 5.0
When heating was performed at various temperatures t for 20 seconds while applying a pressure of kgf / cm 2, the relationship shown in FIG. 5 was obtained between the temperature t and the amount f of the photosensitive resin film 5 penetrated.

On the other hand, the amount of ultraviolet light (wavelength 365 nm) for curing the photosensitive resin film 5 required an exposure amount of 750 mJ / cm 2 in this embodiment.

Next, the nozzle plate 1 is immersed in an electrolytic solution in which particles of a water-repellent polymer resin such as nickel ion and polytetrafluoroethylene are dispersed by electric charge, and the nozzle plate 1 is stirred while the solution is being stirred. An eutectoid plating layer 6 is formed on the surface (FIG. 3C).

As the fluorine-based polymer material used in the eutectoid plating, a resin such as polytetrafluoroethylene, polybarfluoroalkoxybutadiene, polyfluorovinylidene, polyfluorovinyl, or polydiperfluoroalkyl fumarate is used alone. Used as a mixture or as a mixture.

The matrix of the plating layer 6 is not particularly limited, and an appropriate metal such as nickel, copper, silver, zinc, and tin can be selected. Preferably, nickel, nickel-cobalt alloy, nickel-phosphorus, and the like are used. Alloys, nickel-boron alloys, and the like having high surface hardness and excellent wear resistance are selected.

Thus, the particles of polytetrafluoroethylene uniformly cover the surface 2 of the nozzle plate 1 and the inner periphery of the nozzle 4 up to a point at a given depth from the surface 2.

Thereafter, the photosensitive resin film 5 that has entered the back surface 3 of the nozzle plate 1 and the nozzle 4 is dissolved and removed using an appropriate solvent, and then a load is applied to the nozzle plate 1 to generate warpage. At a temperature higher than the melting point of polytetrafluoroethylene, for example, 3
By heating at a temperature of 50 ° C. or more, an ink-repellent plating layer 6 having high hardness is formed on the surface 2 of the nozzle plate 1 and the inner peripheral surface of the nozzle up to a given depth (FIG. (D)).

Therefore, in the nozzle plate 1 configured as described above, as shown in FIG. 2, the inner edge of the nozzle 4 of the ink-repellent plating layer 6 is located at the vibration center A of the ink meniscus.
Is an important factor in determining

The gap volume in the nozzle from the surface 2 of the nozzle 4 to the vibration center A of the meniscus is Vm,
Assuming that the volume from the surface 2 to the front surface B of the ink immediately before ejection, that is, the ink amount of one ink droplet to be ejected is Vi, the smaller the penetration amount d of the plating layer 6 is, the smaller Vm / Vi is. 6 can be reduced, and an expensive driver can be eliminated. On the other hand, if the penetration amount d is made too small, the piezo driving voltage shown in FIG. A flight bend occurs as seen in

On the other hand, when the penetration amount d of the plating layer 6 is large, the drawing position C of the meniscus after the ink discharge becomes deep, so that the bubble is drawn from the front surface of the nozzle 4 or when the next ink droplet is discharged. Insufficient ink supply occurs to cause ejection failure.

A nozzle plate 1 having a thickness of 80 .mu.m having variously different penetration amounts d of the ink-repellent plating layer 6 is prepared, and these are mounted on an on-demand type ink jet printer adopting a piezo drive system. An experiment was conducted 100 times in which a 0.1 μg / dot ink droplet was fully ejected from the nozzle 4 at a response frequency of 5 KHz for 30 seconds, and the flight bending, ejection failure, and the like at that time were counted. The following results were obtained. Was.

[Table 1]

According to this experiment, the ratio of Vm / Vi, that is, the ratio of the void volume Vm in the nozzle 4 from the surface 2 of the nozzle plate 1 to the meniscus formation surface A to the ink amount Vi of one ink droplet to be ejected is 0. Below 04,
It has been found that the flight skew of the ink droplet sharply increases, and that when this ratio exceeds 0.50, ejection failure occurs rapidly.

The above is an experimental result of the nozzle 4 having the cylindrical orifice portion 4b on the front surface 2 side and the funnel-shaped portion 4a having a large opening on the rear surface 3 side. As shown in FIG. Nozzle 14 gently opened like a trumpet from orifice portion 14b on the front surface 2 side to back surface 3 side
As a result of the experiment, it became clear that the same tendency was exhibited.

From the above, Vm / Vi is set to 0.
It has been found that the penetration amount d of the plating layer 6 should be determined so as to be in the range of 04 to 0.50, more preferably in the range of 0.05 to 0.35.

FIG. 4 shows a second embodiment of the surface treatment method for the nozzle plate 1.

In this method, first, an elastic plate 7 made of rubber or the like is pressed against the surface 2 of the nozzle plate 1 with a predetermined pressing force, and a part of the elastic plate 7 is inserted into the nozzle 4 by an amount corresponding to the required insertion amount d. Let And then, nozzle 4
A dry film resist or an appropriate plasticizer 8 is applied as a masking material 8 to the entire back surface 3 of the nozzle plate 1 including the portion (FIG. 4A).

Next, when a dry film resist is used as the masking material 8, ultraviolet rays are irradiated from the back surface 3 to cure it, and when another plasticizer is used, heating or normal drying is performed. After being solidified by the treatment, the elastic material 7 is removed from the surface 2 of the nozzle plate 1 (FIG. 4B).

Next, the nozzle plate 1 is placed in an electrolyte in which particles of a water-repellent polymer resin are dispersed by electric charge.
To form an ink-repellent coating layer 9 made of an eutectoid plating layer on the surface 2 or a fluorine-based polymer water repellent on the surface 2 of the nozzle plate 1 by sputtering or dipping. (Fig. 4
(C)) Finally, the masking material 8 is dissolved and removed from the back surface 3 of the nozzle plate 1 by using an appropriate processing liquid (FIG. 4D).

[0031]

As described above, according to the present invention, the void volume in the nozzle from the surface of the nozzle plate to the surface on which the meniscus is formed has a volume of 0.1.
Since the ink-repellent coating layer was made to enter the nozzle so as to be in the range of 05 to 0.50, the vibration position of the meniscus was correctly regulated by this coating layer, without causing flight bending and ejection failure, In addition, ink droplets can be ejected with the lowest possible piezo drive energy.

[Brief description of the drawings]

FIGS. 1A to 1D are views showing an embodiment of a molding process of a nozzle plate according to the present invention.

FIG. 2 is a cross-sectional view showing an enlarged main part of an embodiment of the nozzle plate of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the nozzle plate of the present invention, in which main parts are enlarged.

FIGS. 4A to 4D are views showing another embodiment of the forming process of the nozzle plate of the present invention.

FIG. 5 is a diagram showing the relationship between temperature and the amount of photosensitive resin film entering the nozzle.

FIG. 6 is a diagram showing the relationship between Vm / Vi and the number of occurrences of flight deflection and ejection failure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Nozzle plate 4 Nozzle 5 Photosensitive resin film 6 Eutectoid plating layer 7 Elastic plate 8 Masking layer 9 Ink repellent coating layer Vm Void volume in nozzle from surface of nozzle plate to meniscus formation surface Vi Volume of ink droplet to be ejected

Continued on the front page (72) Inventor Masao Yamamori 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Kazushige Hageta 3-3-5 Yamato Suwa City, Nagano Prefecture Seiko Epson Corporation (72) Inventor Yukiyoshi Inaka 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation

Claims (3)

[Claims] 1. The nozzle plate according to claim 1, wherein a void volume in the nozzle from a surface of the nozzle plate to a meniscus forming surface is in a range of 0.05 to 0.50 with respect to an ink amount of one ink droplet to be ejected. A nozzle plate for a piezo-drive type ink jet recording head, wherein a part of an ink-repellent coating layer covering the surface is inserted into the inner surface of the nozzle. 2. A nozzle plate for a piezo-drive type ink jet recording head according to claim 1, wherein said ink repellent coating layer is formed by eutectoid plating. 3. The nozzle plate for a piezo-drive type ink jet recording head according to claim 1, wherein said ink-repellent coating layer is formed of a fluoropolymer resin material other than said eutectoid plating.