JP2003025590A - Nozzle plate and method for manufacturing nozzle plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle plate where a nozzle is formed round in an ink jet direction with its diameter reduced, and a method for manufacturing the nozzle plate simply and accurately. SOLUTION: An ink jet head 1 has a plurality of nozzles 2 formed to respectively communicate with a plurality of liquid chambers where ink is filled. The nozzle 2 has its diameter 2r reduced from an ink inflow part 2i from which the ink enters to an ink discharge part 2o where the entering ink is discharged. A cross section of the nozzle 2 is formed to be smoothly round. Particularly, the nozzle 2 is formed so that a value x (x=n/N) obtained by dividing a diameter n at a 3/5 point of a thickness D between end parts of an R shape part by a diameter N of the ink discharge part 2o is in a range of 1<=x<=1.7. Accordingly, ink can be fully discharged by a low driving voltage, and the ink discharge performance is improved, thus enabling saving power, printing at high speed and driving with a high printing quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle plate and a method for manufacturing the nozzle plate, and more particularly, to a nozzle plate having nozzles each having a small diameter in a round shape in the ink ejection direction and the nozzle plate. The present invention relates to a method for manufacturing a nozzle plate that can be manufactured easily and accurately.

[0002]

2. Description of the Related Art Ink jet recording apparatuses are capable of non-contact recording without the need for processes such as development and fixing, so that colorization is easy and noise during recording is extremely low. Since it has many advantages such as high-speed printing, high flexibility of ink, and use of cheap plain paper, it has spread to image forming apparatuses such as printers, copying machines, and facsimile machines. There is.

Among these ink jet systems, the so-called drop-on-demand type, which ejects ink droplets only when print recording is required, is currently in the mainstream because it does not require recovery of ink droplets unnecessary for recording.

Such an ink jet recording apparatus generally has a nozzle plate having a plurality of nozzles formed therein, an ink liquid chamber in which each nozzle communicates with each other, and an actuator arranged corresponding to each nozzle. Recording is performed on a recording material such as paper by pressurizing ink in the ink liquid chamber by displacement of the actuator, heat generation, and the like to eject ink droplets from the nozzle holes.

However, recent ink jet recording apparatuses are required to have high speed and high print quality, and in order to achieve high speed and high print quality, it is necessary to use multiple nozzles and have a high density. When a piezoelectric element is used as an actuator, it is difficult to finely process the piezoelectric element and bond it to each diaphragm, and the dimensional accuracy in conventional machining causes large variations in print quality. Therefore, the method using the piezoelectric element cannot support high speed and high print quality.

Further, in the conventional ink heating system, since the ink is heated by the thin-film resistance heating body, it is possible to deal with the multi-nozzle and high density. However, there is a problem that the resistance heating body is easily damaged by repeated rapid heating / cooling during driving and shock when bubbles disappear, and the life of the inkjet head is short.

As a method for solving the above-mentioned problems,
As a drive means of the actuator, there is a so-called electrostatic system in which a vibrating plate is vibrated by using an electrostatic force to eject ink, and this electrostatic system inkjet head can be miniaturized and densified. Further, it has the advantage of a long life.

However, the electrostatic type ink jet head is, for example,
There is a problem that the driving force is small. That is, an inkjet head using a laminated piezoelectric element has a large driving force because several tens of piezoelectric elements are laminated, a voltage is applied in parallel to each element, and a mechanical displacement amount is taken out in series. However, in the electrostatic ink jet head, the driving force is generally small because the driving is simply based on the displacement recovery force of the diaphragm. For example, in an electrostatic ink jet head, when the inner shape of the nozzle is a straight shape or when the inner shape of the nozzle is a substantially straight shape with a taper angle of 5 ° or less, sufficient ink ejection with a small driving voltage is possible. Hard to do.

As an inexpensive method for forming a straight nozzle on a nozzle plate, electroforming is performed on a conductive substrate on which a dry film resist corresponding to the nozzle is patterned, and then the substrate and the dry film resist are peeled off. There are ways. Further, a large taper can be formed inside the nozzle by changing the exposure amount condition and the like.

However, when forming a large number of nozzles on the nozzle plate, it is difficult to stably form both the nozzle diameter accuracy and the taper angle control.

Further, in recent years, energy saving has been actively demanded also in image forming apparatuses such as printers, copying machines and facsimile machines, and it is important for an ink jet head to obtain sufficient characteristics with a small driving energy. It is one of the characteristics.

Further, as for high printing quality, an inkjet head utilizing electrostatic force has a great influence on the ejection performance due to the nozzle shape, like other types of inkjet heads, and further improvement is required. Regarding the influence of the shape inside the nozzle on ejection, the shape inside the nozzle affects the way energy is propagated from the energy generating means to the ink and the process in which the ink passes through the nozzle to form ink droplets. Shape greatly affects image quality.

Conventionally, a plurality of plate-shaped bodies of different materials having different inclination angles of holes opened by laser beam irradiation are sequentially laminated from the one having the smaller inclination angle, and the plate-shaped body having the smaller inclination angle is formed. A method for manufacturing a nozzle plate of an ink jet recording head in which a laser beam is irradiated from the side of the body to form an opening in which the taper angle in each material layer is gradually increased, and the opening is used as a nozzle. Has been proposed (see Japanese Patent Laid-Open No. 11-91114).

That is, according to the method for manufacturing the nozzle plate of the ink jet recording head, when the nozzles are opened by irradiating the laser beam, the nozzle forming member is combined with plate materials having different inclination angles when the holes are opened, so that the nozzle cross section is The shape is formed into a substantially R shape to sufficiently reduce the fluid resistance to the ink and improve the ink ejection efficiency.

Further, conventionally, JP-A-8-132614, JP-A-8-276589 and JP-A-10-5.
Japanese Patent No. 8679 discloses a method of producing a nozzle by electroforming, and by utilizing the fact that the electrodeposited film protrudes on the surface of the electrically insulating film, a nozzle shape is formed in the R shape of the electrodeposited film. Trying to. In addition, JP-A-8-13261
Japanese Patent Laid-Open No. 4 and Japanese Patent Application Laid-Open No. 8-276589 disclose that the inside of the R shape formed by electroforming is coated with a resin to control the inside shape.

[0016]

However, the techniques described in the above publications still need to be improved in order to manufacture a nozzle plate having good ejection characteristics with a small amount of energy.

That is, in the method for manufacturing a nozzle plate of an ink jet recording head described in Japanese Patent Laid-Open No. 11-91114, at least some discontinuous points are generated in the inner cross section of the nozzle, and the ink in the nozzle is There is a possibility that the fluctuation of the meniscus may be adversely affected and the ink ejection characteristics may be deteriorated, and a problem in terms of strength of the interface between different materials may occur.

Further, JP-A-8-132614, JP-A-8-276589 and JP-A-10-5867.
In the technique described in Japanese Patent Publication No. 9, an R is formed inside the nozzle by using electroforming.
Even if an attempt is made to form a shape, it is not possible to control the R shape with high precision to improve the ejection performance, and it is not possible to stably form a nozzle shape having the same profile.
As a result, there is a problem in that the nozzle holes have different shapes and the ejection characteristics may deteriorate.

Further, in JP-A-8-132614 and JP-A-8-276589, it is attempted to control the internal shape by coating the inside of the R shape formed by electroforming with a resin. Since it is not possible to control the R shape with high precision, it is difficult to make the inner shape constant by coating with a resin.

Therefore, according to the first aspect of the present invention, a plurality of nozzles that communicate with a plurality of liquid chambers filled with ink are formed, and the liquid is generated by the restoring force of the diaphragm that is deformed by electrostatic force. The diameter of the nozzle of the nozzle plate for ejecting the ink in the liquid chamber from the nozzle due to the pressure change in the chamber becomes smaller from the ink inflow side where the ink in the liquid chamber flows in to the ink ejection side for ejecting the inflowing ink. In addition, by making the cross-sectional shape into a smooth round shape, the driving force is effective even in the electrostatic system where the nozzle has a small fluid resistance and is a continuous surface and the driving force is relatively small. That is, it is possible to sufficiently discharge the ink with a low driving voltage and to improve the ink discharge performance to save power, achieve high-speed printing and high print quality. Is an object of the present invention to provide a nozzle plate.

According to a second aspect of the present invention, the round shape of the nozzle is in the direction from the ink ejection side to the ink injection side, and is 3/5 of the thickness from the end portion to the end portion of the round shaped portion.
Value x obtained by dividing the diameter n at the position n by the diameter N of the ink ejection portion
However, by setting the range of 1 ≦ x ≦ 1.7, the holding power of the ink meniscus can be enhanced, the ink can be ejected strongly against the disturbance, and the refilling of the meniscus can be speeded up further. It is an object of the present invention to provide a nozzle plate that can stably realize high-speed printing and high printing quality.

According to a third aspect of the present invention, a plurality of nozzles that communicate with a plurality of liquid chambers filled with ink are formed, and the inside of the liquid chamber is generated by the restoring force of the diaphragm that is deformed by electrostatic force. When manufacturing a nozzle plate that causes the ink in the liquid chamber to be ejected from a nozzle by a pressure change, an electrical insulating film is formed on a portion that will be a nozzle on a predetermined substrate,
On the surface of the substrate, an organic additive having an S element in the molecule or an organic additive having a benzene ring skeleton, or
After performing electroforming using a plating solution containing an organic additive having a benzene ring skeleton, the electrical insulating film is removed,
A nozzle is formed in which the electrodeposited film is peeled from the substrate, and the diameter of the electrodeposited film is reduced from the ink inflow side into which the ink in the liquid chamber flows to the ink discharge side for discharging the inflowed ink. At the same time, the cross-sectional shape of the nozzle is
By using a nozzle plate that is formed in a smooth round shape, a round shape that smoothly continues from the ink injection side that effectively propagates the driving force to the ink to the ink ejection side that provides meniscus stability and accelerated movement The nozzle plate can be easily manufactured, the lateral growth of the electrodeposited film is suppressed, the dimensional stability of the nozzle discharge hole is improved, the ink discharge accuracy is good, and the nozzle plate with good image quality is easy and high. It is an object of the present invention to provide a method for manufacturing a nozzle plate that can be manufactured with high accuracy.

According to the fourth aspect of the present invention, by applying eutectoid plating of a predetermined water-repellent film on the surface of the nozzle plate on the ink ejection side, ink is prevented from adhering to the periphery of the ink ejection portion of the nozzle plate. An object of the present invention is to provide a nozzle plate manufacturing method capable of manufacturing a nozzle plate capable of stably obtaining high image quality easily and with high accuracy.

[0024]

According to another aspect of the present invention, there is provided a nozzle plate in which a plurality of nozzles communicating with a plurality of liquid chambers filled with ink are formed and which is deformed by electrostatic force. In the nozzle plate that causes the ink in the liquid chamber to be ejected from the nozzle due to the pressure change in the liquid chamber that is generated by the restoring force of
The above-mentioned object is achieved by reducing the size from the ink inflow side into which the ink in the liquid chamber flows to the ink discharge side from which the inflowing ink is discharged, and by forming the cross-sectional shape into a smooth round shape. ing.

According to the above structure, a plurality of nozzles that communicate with a plurality of liquid chambers filled with ink are formed, and the pressure change in the liquid chambers caused by the restoring force of the diaphragm deformed by electrostatic force. In the nozzle of the nozzle plate for ejecting the ink in the liquid chamber from the nozzle, the diameter is reduced from the ink inflow side where the ink in the liquid chamber flows into the ink ejection side for ejecting the inflowing ink,
Since the cross-sectional shape is formed in a smooth round shape, the nozzle has a small fluid resistance, and
As a continuous surface, even with an electrostatic system where the driving force is relatively small, the driving force can be effectively propagated to the ink, sufficient ink ejection can be performed with a low driving voltage, and the ink ejection performance is improved. As a result, power saving, high speed printing and high print quality driving can be performed.

In this case, for example, as described in claim 2, the nozzle is in the direction from the ink ejection side to the ink injection side, and the thickness from the end to the end of the round-shaped portion. Assuming that a value obtained by dividing the diameter n at the position of 3/5 by the diameter N of the ink ejection portion is x (= n / N), even if the x value is in the range of 1 ≦ x ≦ 1.7, Good.

According to the above construction, the round shape of the nozzle has a diameter in the direction from the ink ejection side to the ink injection side and at a position of ⅓ of the thickness from the end to the end of the round shape portion. The value x obtained by dividing n by the diameter N of the ink ejection portion is 1 ≦
Since x is in the range of 1.7, it is possible to enhance the holding power of the ink meniscus to enable strong ink ejection against disturbance, and to refill the meniscus quickly. Higher-speed printing and higher printing quality can be realized in a stable manner.

According to a third aspect of the present invention, there is provided a method for manufacturing a nozzle plate, wherein a plurality of nozzles communicating with a plurality of liquid chambers filled with ink are formed, and a restoring force of a diaphragm deformed by electrostatic force. In the method of manufacturing a nozzle plate in which ink in the liquid chamber is ejected from the nozzles by the pressure change in the liquid chamber that occurs in step 1, an electrical insulating film is formed on a portion of the predetermined substrate that will be the nozzle, , Electroplating using an organic additive having an S element in the molecule or an organic additive having a benzene ring skeleton, or a plating solution containing an organic additive having a benzene ring skeleton is performed, and then an electrical insulating film is formed. To remove the electrodeposited film from the substrate, and the electrodeposited film is discharged from the ink inflow side where the diameter of the electrodeposited film is in the ink chamber into which the inflowing ink is discharged. With smaller the nozzle is formed to the discharge side, by a nozzle plate cross-sectional shape of the nozzle is formed into a smooth round shape, has achieved the above objects.

According to the above construction, a plurality of nozzles that communicate with a plurality of liquid chambers filled with ink are formed, and the pressure change in the liquid chambers caused by the restoring force of the diaphragm deformed by electrostatic force. In manufacturing a nozzle plate for ejecting ink in the liquid chamber from nozzles, an electrically insulating film is formed on a portion of a predetermined substrate that serves as a nozzle, and an organic addition containing an S element in the molecule is formed on the surface of the substrate. After performing electroforming using a plating solution containing an agent or an organic additive having a benzene ring skeleton, or an organic additive having a benzene ring skeleton, the electrical insulating film is removed and the electrodeposited film is removed from the substrate. A nozzle is formed that is peeled off and the diameter of the electrodeposition film is reduced from the ink inflow side into which the ink in the liquid chamber flows to the ink ejection side to eject the inflowing ink. In addition, since the nozzle plate is a nozzle plate in which the cross-sectional shape of the nozzle is formed in a smooth round shape, the driving force is effectively propagated to the ink from the ink injection side to the ink discharge side that brings stability and accelerated movement of the meniscus. It is possible to easily produce a smoothly continuous round shape, suppress the lateral growth of the electrodeposited film, and improve the dimensional stability of the nozzle ejection holes, thus improving the ink ejection accuracy. A good nozzle plate with good image quality can be easily manufactured with high precision.

In this case, for example, as described in claim 4, in the method of manufacturing the nozzle plate, a predetermined water-repellent film may be subjected to eutectoid plating on the surface of the nozzle plate on the ink ejection side. .

According to the above construction, the surface of the nozzle plate on the ink ejection side is subjected to eutectoid plating of a predetermined water-repellent film such as nickel-Teflon (registered trademark). It is possible to easily and highly accurately manufacture a nozzle plate that can prevent ink from adhering and can stably obtain high image quality.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and therefore have various technically preferable limitations. However, the scope of the present invention refers to the present invention particularly in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

1 to 5 are views showing an embodiment of a nozzle plate and a method of manufacturing the nozzle plate of the present invention, and FIG. 1 is an embodiment of the method of manufacturing the nozzle plate and the nozzle plate of the present invention. FIG. 7 is a front sectional view of a nozzle plate to which the above embodiment is applied.

In FIG. 1, the nozzle plate 1 is formed of a metal such as nickel, cobalt, manganese, copper, iron, zinc, etc. Although only one nozzle plate 1 is shown in FIG. , A plurality of nozzles 2 are formed. The nozzle 2 is formed in a circular shape whose diameter 2r decreases from the ink inflow portion 2i toward the ink ejection portion 2o, and the inner wall surface of the nozzle 2 extends from the ink inflow side 2i to the ink ejection side 2o. It is formed in an R shape (round shape) that is smoothly continuous toward the side. In particular, the nozzle 2 has a cross-sectional shape in the vicinity of the ink ejection portion 2o, which is formed into a substantially truncated cone shape that is close to a cylindrical shape.

In the R shape of the nozzle 2, the diameter of the nozzle 2 in the direction from the ink ejection portion 2o to the ink inflow portion 2i and at the 3/5 point of the thickness D between the end portions of the R shaped portion. The value obtained by dividing n by the diameter N of the ink ejection portion 2o is x (x
= N / N), the R shape is formed so that the value x is in the range of 1 ≦ x ≦ 1.7.

The nozzle 2 of the nozzle plate 1 is manufactured by the following manufacturing process. That is, as shown in FIG. 3, first, as the substrate 10, at least a member having conductivity on its surface, for example, stainless steel (SUS) is used, and the substrate 10 is deformed by the stress generated by Ni electrodeposition described later. It has a sufficient thickness.

On this substrate 10, as shown in FIG. 3, an electric insulating film 11 such as a dry film resist (DFR) is formed.
Is patterned, electroforming such as Ni electroforming is performed on the surface, and then the electric insulating film 11 is removed. Further, the electrodeposited film 12 is peeled off from the substrate 10, and the electrodeposited film 12 is attached to the nozzle 2
And the nozzle plate 1 is formed. As the material of the nozzle plate 1, metals such as nickel, cobalt, manganese, copper, iron and zinc can be used.

Although the method of manufacturing the nozzle plate 1 has been described as electroforming, the nozzle plate 1 having the nozzles 2 may be manufactured by a method such as pressing.

In the method for manufacturing the nozzle plate 1 described above, when the R-shaped nozzle 2 is manufactured inside the nozzle 2 by using at least electroforming as a part of the process, an organic element having an S element in its molecule is used. A plating solution containing an additive or an organic additive having a benzene ring skeleton is used. As the organic additive having the S element in the molecule or the organic additive having a benzene ring skeleton, sulfonic acid-based, sulfonamide-based, sulfonimide-based, coumarin or saccharin and salts thereof, and the like can be used. When an organic substance containing these S elements in the molecule or an organic additive having a benzene ring skeleton is added to the plating solution, the organic additive is adsorbed on the electrodeposition surface, and crystal growth in the film thickness direction occurs. Suppression, relaxation of the current density distribution and suppression of concentrated precipitation in the high current density portion are performed. Further, due to the plating stress distorted in the tangential direction of the outer circumference of the nozzle 2, the distortion in the center direction of the nozzle 2 also affects the R shape. Therefore, for example, as shown in FIG. 3, when the nozzle plate 1 is manufactured by electroforming, the electrode plate is protruded onto the electric insulating film 11 to suppress the electrodeposition of the portion forming the nozzle discharge portion 2o side, and as a result, A substantially frustoconical shape close to a substantially columnar shape is formed, in which the R-shaped slope is steep from the ink injection portion 2i side to the ink ejection portion 2o side. In addition, the nozzle plate 1
When electroforming under the above conditions, the electrical insulation film 1
By suppressing the protrusion of the electrodeposition on the surface 1, the amount of the electrodeposition with respect to the diameter of the electric insulating film 11 is reduced,
A deformed shape that is likely to occur when protruding is less likely to occur, the shape of the nozzle 2 is stabilized, and high-quality image formation is possible.

Next, the operation of this embodiment will be described. The nozzle plate 1 of the present embodiment is formed of a metal such as nickel, cobalt, manganese, copper, iron and zinc, and the nozzle plate 1 has a diameter 2r from the ink inflow portion 2i to the ink ejection portion 2o. The nozzle 2 is formed in a circular shape having a circular shape that becomes smaller toward the side of the nozzle 2. The inner wall surface of the nozzle 2 is formed in an R shape that is smoothly continuous from the ink inflow portion 2i side toward the ink ejection portion 2o side. In particular, the nozzle 2 has a cross-sectional shape as shown in FIG.
In the vicinity of the ink ejection portion 2o, it is formed in a substantially truncated cone shape that is close to a cylindrical shape. Furthermore, the nozzle 2 has its R
In terms of shape, from the ink injection portion 2i to the ink ejection portion 2o
As a value indicating the R shape extending to the side, the ink ejection portion 2o
Is evaluated using the ratio of the diameter N of the nozzle 2 to the diameter of the inside of the nozzle 2,
Diameter n at the 3/5 point of the thickness D between the end portions of the R-shaped portion
Is divided by the diameter N of the ink ejection portion 2o, x (x = n
/ N), the value x is 1 ≦ x ≦ 1.
In the case of the range of 7, the ink droplet volume Mj and the ink droplet ejection speed Vj at the ink ejection portion 2o are stable, and stable and high-quality images and high-speed print recording are possible. 2, the diameter N of the ink ejection portion 2o is set to R
A value x, which is obtained by dividing the thickness D between the end portions of the shape portion by the diameter n at the 3/5 point, is formed in an R shape such that 1 ≦ x ≦ 1.7.

Therefore, the nozzle plate 1 of the present embodiment has less fluid resistance than the nozzle plate in which the inside of the nozzle plate 1 is straight from the ink ejection portion side to the ink injection portion side, and further, the nozzle plate 1 with respect to the drive element. The ink contact area can be increased, and the displacement energy of the vibration plate due to the electrostatic force having a weak driving force can be sufficiently propagated to the ink in the ink injection portion 2i of the nozzle plate 1. Further, since the R shape of the nozzle 2 is smoothly and continuously recessed from the ink ejection portion 2o side to the ink injection portion 2i side, there is no discontinuous point in its cross-sectional shape,
Stable ink ejection can be performed.

That is, it has been conventionally known that the shape of the nozzle 2 of the nozzle plate 1 has a great influence on the characteristics of the ink droplet. For example, the diameter of the ink ejection portion 2o is the ink droplet volume Mj and the ink droplet ejection. The velocity Vj is greatly influenced, and the shape inside the nozzle 2 has a great influence on the ejection direction and ejection stability of the ink droplets.

The internal shape of the nozzle 2 has a great influence on the ejection of ink droplets due to the change in the state of the meniscus of the ink formed inside the nozzle 2, and in particular, the refilling of the ink (ink meniscus Refilling to initial position) affects image quality and recording speed. The ink meniscus is formed in the smallest diameter portion of the nozzle 2, and after the ink is ejected from the nozzle 2,
The meniscus position of the ink largely changes to the state of being drawn toward the ink injecting portion 2i, but when this ink is drawn into the nozzle 2, it returns to the initial meniscus position before the next ink droplet is ejected. Is required. If a drive signal for ejecting the next ink drop is input before the ink meniscus has fully returned, the volume Mj of the ink drop becomes small and the ejection speed V of the ink drop.
j becomes faster. Then, as described above, the volume Mj of the ink droplet and the ejection speed Vj of the ink droplet have a great influence on the output image in the drop-on-demand type inkjet head, and the volume Mj of the ink droplet and the ejection of the ink droplet. When the speed Vj is unstable, the quality of the output image is deteriorated. Further, by returning the ink meniscus to the initial position at a faster timing, it is possible to increase the drive frequency of ink droplet ejection and increase the recording speed.

Here, there are the following methods for controlling the speed at which the ink meniscus returns to the initial position. First, the first method is the magnitude of the capillary force in the nozzle, and by decreasing the inner diameter of the nozzle, the capillary force is increased and the meniscus return speed can be increased. However, when it is attempted to control the capillary force by reducing the inner diameter of the nozzle, the volume Mj of the ink droplet is increased.
It causes a problem that becomes smaller.

Then, in order to improve the capillary force without reducing the volume Mj of the ink droplet, the inner shape of the nozzle should be closer to the ink ejection portion 2o side like the nozzle 2 of the nozzle plate 1 of the present embodiment. It is preferable that the shape is continuously narrowed down. The influence of the shape of the nozzle 2 on the performance of the ink jet head includes the change in the ink refill ability as described above, the change in the image quality and the recording speed due to the change in the ink refill ability, and the resistance to various disturbances. There is For example, various disturbances such as vibration generated by reciprocating movement during printing and residual vibration caused by driving of the adjacent nozzle 2 may occur in the nozzle plate 1, and when such disturbance occurs. , The meniscus of the ink is affected, and the output image is likely to be disturbed. In order to make the nozzle strong against such disturbance, it is preferable that the ink meniscus does not fluctuate. For that purpose, the internal shape of the nozzle should be substantially the same as the meniscus forming part in a substantially cylindrical shape. You can deal with it.

That is, in order to perform high-quality images and high-speed print recording, and further, to form images that are robust against disturbance and always stable, the cross-sectional shape thereof is the same as that of the nozzle 2 of the nozzle plate 1 of the present embodiment. It is desirable that the R shape, in particular, the substantially frustoconical shape close to the cylindrical shape near the ink ejection portion 2o, as shown in FIG.

As a result of the experiment, in the R shape of the nozzle 2, as a value indicating the R shape from the ink injecting portion 2i side to the ink ejecting portion 2o side, as described above, the diameter N of the ink ejecting portion 2o. And the diameter on the inner side of the nozzle 2 are evaluated, and the direction is the direction from the ink ejection portion 2o to the ink inflow portion 2i, and the thickness is 3/5 at the end portion of the R-shaped portion. When the value x is a value obtained by dividing the diameter n in (1) by the diameter N of the ink ejecting portion 2o, and the value x is in the range of 1 ≦ x ≦ 1.7, the ink ejecting portion 2o Volume M of ink drop at
j and the ink droplet ejection speed Vj are stable, and stable and high-quality images and high-speed print recording are possible. For example, when the R shape of the nozzle 2 of FIG. 1 and the R shape of the nozzle 2 of FIG. 2 are compared, the R shape of the nozzle 2 of FIG. 2 has a stable ink droplet volume Mj and ink droplet ejection speed Vj. It is possible to obtain a high-quality image and high-speed print recording, and further, it is possible to perform stable image formation that is resistant to disturbance and is always stable.

In the nozzle plate 1 of this embodiment, the surface of the nozzle plate 1 on the ink ejection portion 2o side may be subjected to eutectoid plating of a water repellent film such as nickel-Teflon (registered trademark).

By doing so, it is possible to prevent ink from adhering to the periphery of the ink ejection portion 2o of the nozzle plate 1, and it is possible to stably obtain high image quality.

[0050]

EXAMPLES <Comparative Example> As a comparative example, a nozzle plate having straight nozzles was prepared and joined to an electrostatic drive actuator to form an inkjet head.

This nozzle plate is 34.4 × 7.2.
mm, the film thickness is 50 μm, and two nozzle rows each having 192 nozzles are formed. The nozzle has a diameter of 20 μm and is formed in a straight shape. The nozzle plate was formed by electroforming nickel on a SUS substrate on which a dry film resist corresponding to the nozzle was patterned, and then peeling off the substrate and the dry film resist to form a nozzle plate having straight nozzles. . The straight shape of the nozzle is about 5 depending on the dry film patterning conditions.
A taper of ° is provided.

When the ink jet head equipped with this nozzle plate is driven and evaluated, the ink ejection speed Vj is set to 7 m / s. The voltage required for driving is shown in FIG. So that 36V
Met.

When ink droplets were ejected using this nozzle plate, the diameter accuracy within one plate was ± 1.5 μm.
m (see FIG. 4).

Example 1 As Example 1, a nozzle plate having round-shaped nozzles was prepared and bonded to an electrostatic drive actuator to form an ink jet head.

This nozzle plate is similar to the comparative example.
The size is 34.4 × 7.2 mm, and two nozzle rows each including 192 nozzles are formed.

For this nozzle plate, nickel electroforming was performed on a SUS substrate on which a dry film resist was patterned to a diameter of 80 μm and a thickness of 1.1 μm, and then SUS was performed.
It was formed by peeling the substrate and the resist.

At this time, the shape of the nozzle did not follow the pattern of the dry film resist, but the electrodeposited film was made to protrude and grow on the surface of the dry film to form a round shape. The film thickness of the electrodeposition was 30 μm as in the comparative example.
It was about m. At this time, the film thickness was adjusted so that the nozzle diameter was 20 μm. The plating solutions used were as follows: plating solution: nickel sulfamate plating, surface tension: 41 dyne / cm, pH: 4.0 (adjusted with boric acid and sulfamic acid).

At this time, the value x obtained by dividing the diameter n at the point of 3/5 of the thickness between the end portions of the R portion of the nozzle by the diameter N of the ink ejection portion is 2.0 (x = 2.0) (see FIG. 4).

When this nozzle plate was attached to an electrostatically driven ink jet head and evaluated in the same manner as in the comparative example, when the ink ejection speed Vj was set to 7 m / s, the voltage required for driving was As shown in FIG. 4, the voltage was 30V, which was 6V lower than that of the straight nozzle of the comparative example.

The diameter accuracy in one plate is ± 0.6.
The driving frequency was 12 kHz (see FIG. 4) in the region where the ink ejection speed Vj fluctuates within ± 1 m / s.

Example 2 As Example 2, a nozzle plate having round-shaped nozzles was prepared and bonded to an electrostatic drive actuator to form an ink jet head.

Similar to the first embodiment, this nozzle plate is 34.4 × 7.2 mm, and two nozzle rows each having 192 nozzles are formed.

This nozzle plate was manufactured by the same manufacturing method as in Example 1, but an organic additive (naphthalene-1,3,6-trisodium trisodium salt) containing S element in the molecule was added to the plating solution. In addition, the concentration was adjusted to 0.9 g / l to prepare a nozzle plate having round-shaped nozzles.

At this time, the value x obtained by dividing the diameter n at the point of 3/5 of the thickness between the end portions of the R portion of the nozzle by the diameter N of the ink ejection portion is 1.7 (x = 1.7) (see FIG. 4).

When this nozzle plate was attached to an electrostatically driven ink jet head and evaluated in the same manner as in the comparative example, when the ink discharge speed Vj was set to 7 m / s, the voltage required for driving was as shown in FIG. As shown in FIG. 4, as in Example 1, the voltage was 30 V, and the diameter accuracy in one plate was further improved to ± 0.6 μm (see FIG. 4). Regarding the drive frequency characteristic, the drive frequency in the region where the ink ejection speed Vj fluctuates within ± 1 m / s is 14 kHz (see FIG. 4), and the printing speed can be further increased. .

<Example 3> As Example 3, a nozzle plate having round-shaped nozzles of Example 2 was prepared and joined to an electrostatic drive actuator to form an ink jet head.

Similar to the first embodiment, this nozzle plate is 34.4 × 7.2 mm, and two nozzle rows each having 192 nozzles are formed.

This nozzle plate was prepared by the same manufacturing method as in Example 1, except that an organic additive containing S element in the molecule was adjusted to 3.0 g / l in a plating solution to form a round nozzle. Was prepared.

At this time, the value x obtained by dividing the diameter n at the point of 3/5 of the thickness between the end portions of the R portion of the nozzle by the diameter N of the ink ejection portion is 1.5 (x = 1.5) (see FIG. 4).

When this nozzle plate was attached to an electrostatically driven ink jet head and evaluated in the same manner as in the comparative example, when the ink discharge speed Vj was set to 7 m / s, the voltage required for driving was As shown in FIG. 4, the voltage was 31 V, which was about the same as in Example 1, and the diameter accuracy in one plate was further improved to ± 0.4 μm (see FIG. 4). Regarding the drive frequency characteristic, the drive frequency in the region where the ink ejection speed Vj fluctuates within ± 1 m / s is 16 kHz (see FIG. 4), and it is possible to further increase the recording speed. .

Example 4 As Example 4, a nozzle plate having the round nozzles of Example 2 was prepared and joined to an electrostatic drive actuator to form an ink jet head.

Similar to the first embodiment, this nozzle plate is 34.4 × 7.2 mm, and two nozzle rows each having 192 nozzles are formed.

This nozzle plate was prepared by the same manufacturing method as in Example 1, except that the organic additive containing S element in the molecule was adjusted to 7.0 g / l in the plating solution to prepare a round nozzle. Was prepared.

At this time, the value x obtained by dividing the diameter n at the point 3/5 of the thickness between the end portions of the R portion of the nozzle by the diameter N of the ink ejection portion is 1.3 (x = 1.3) (see FIG. 4).

When this nozzle plate was attached to an electrostatically driven ink jet head and evaluated in the same manner as in the comparative example, when the ink ejection speed Vj was set to 7 m / s, the voltage required for driving was As shown in FIG. 4, the voltage was 31.5 V, which was the same level as in Example 1, and the diameter accuracy in one plate was ± 0.4 μm (see FIG. 4). Regarding the drive frequency characteristic, the drive frequency in the region where the ink ejection speed Vj fluctuates within ± 1 m / s is 18
Since the frequency is kHz (see FIG. 4), the recording speed can be further increased.

Then, in Examples 1 to 4, when the nozzle surface was plated with a Ni-PTFE eutectoid plating film, there was no ink residue and stable ejection could be realized.

Example 5 As Example 4, a nozzle plate having the round nozzles of Example 2 was prepared and joined to an electrostatic drive actuator to form an ink jet head.

This nozzle plate has a size of 34.4 × 7.2 mm and has two nozzle rows each having 192 nozzles in a row, as in the first embodiment.

The nozzle plate has a dry film resist patterning diameter of 120 μm and a film thickness of
The thickness was 1.1 μm, and the film thickness was 50 μm.

At this time, the concentration of the organic additive having the S element in the molecule added to the plating solution was varied and the diameter of the nozzle on the ink ejection side and the diameter of the ink injection side were measured. The ratio of the diameter on the ink injection side / the diameter on the ink ejection side with respect to the concentration of the organic additive contained in Example 2 changed as shown in FIG.

As can be seen from FIG. 5, it was confirmed that the higher the concentration of the organic additive containing S element in the molecule, the smaller the ratio of the diameter on the ink injection side / the diameter on the ink ejection side, and the smaller the amount of protrusion. We were able to. The nozzle size became stable as the ratio of the diameter of the ink injection side / the diameter of the ink ejection side decreased.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

[0083]

According to the nozzle plate of the first aspect of the present invention, a plurality of nozzles, which communicate with a plurality of liquid chambers filled with ink, are formed, and the diaphragm which is deformed by electrostatic force is restored. Ink ejection for ejecting the inflowing ink from the ink inflow side where the ink in the liquid chamber is ejected from the ink inflow side where the ink in the liquid chamber is ejected by the pressure change in the liquid chamber caused by the force As the cross-sectional shape of the nozzle is reduced to the side and formed into a smooth round shape, the nozzle has a small fluid resistance and is a continuous surface, and even with an electrostatic system with a relatively small driving force, The driving force can be effectively transmitted to the ink, sufficient ink ejection can be performed with a low driving voltage, and the ink ejection performance is improved to save power. It can be driven in high-speed printing and high printing quality.

According to the second aspect of the nozzle plate of the present invention, the round shape of the nozzle has a thickness of 3 from the end of the round-shaped portion to the end of the round-shaped portion in the direction from the ink ejection side to the ink injection side. Since the value x obtained by dividing the diameter n at the position of / 5 by the diameter N of the ink ejection portion is in the range of 1 ≦ x ≦ 1.7, the holding force of the ink meniscus is increased,
It is possible to eject ink that is strong against disturbance.
Further, the refilling of the meniscus can be accelerated, and higher speed printing and high printing quality can be stably realized.

According to the method for manufacturing a nozzle plate of the third aspect of the present invention, a plurality of nozzles that respectively communicate with a plurality of liquid chambers filled with ink are formed, and a vibration plate that is deformed by electrostatic force is formed. When manufacturing a nozzle plate that ejects the ink in the liquid chamber from the nozzles by the pressure change in the liquid chamber generated by the restoring force, an electrical insulating film is formed on the portion of the predetermined substrate that will become the nozzle, and on the surface of the substrate. ,
After performing electroforming using a plating solution containing an organic additive having an S element in the molecule or an organic additive having a benzene ring skeleton, or an organic additive having a benzene ring skeleton, the electrically insulating film is removed. Then, the electrodeposited film is peeled off from the substrate, and the diameter of the electrodeposited film is reduced from the ink inflow side into which the ink in the liquid chamber flows to the ink discharge side for discharging the inflowed ink. In addition, since the nozzle plate is formed so that the cross-sectional shape of the nozzle is a smooth round shape, the driving force is effectively propagated to the ink, and the stability and accelerated movement of the meniscus are provided from the ink injection side. A round shape that smoothly continues to the ink ejection side can be easily produced, and lateral growth of the electrodeposited film can be suppressed to improve the nozzle ejection hole. It is possible to improve the law stability, the ink ejection accuracy is good, it is possible to produce a good nozzle plate of the image quality easily and highly accurately.

According to the method for manufacturing a nozzle plate of the fourth aspect of the invention, the surface of the nozzle plate on the ink ejection side is subjected to eutectoid plating of a predetermined water-repellent film such as nickel-Teflon (registered trademark). Therefore, it is possible to prevent ink from adhering to the periphery of the ink ejection portion, and it is possible to easily and highly accurately manufacture a nozzle plate that can stably obtain high image quality.

[Brief description of drawings]

FIG. 1 is an enlarged front sectional view of a nozzle portion of a nozzle plate to which an embodiment of a nozzle plate and a method for manufacturing the nozzle plate of the present invention is applied.

FIG. 2 is an enlarged front cross-sectional view of a nozzle of the nozzle plate shown in FIG.

FIG. 3 is a front cross-sectional view showing a process of manufacturing the nozzle plate of FIG. 1, showing a state in which an electric insulating film is formed on a substrate and a nozzle plate is manufactured by electrodeposition.

FIG. 4 is a nozzle shape of Comparative Example and Examples 1 to 4;
The figure which compares and shows x value, drive power, drive frequency, and diameter accuracy.

FIG. 5 is a diagram showing the relationship between the concentration of an organic additive having an S element in the molecule added to the plating solution and the ratio of the injection side diameter / ejection side diameter of the nozzle.

[Explanation of symbols]

1 nozzle plate 2 nozzles 2i Ink inlet 2o ink ejector 2r nozzle diameter 10 substrates 11 Electric insulation film 12 Electrodeposition film

Claims (4)

[Claims] 1. A plurality of nozzles, which communicate with a plurality of liquid chambers filled with ink, are formed, and the liquid is changed by a pressure change in the liquid chamber generated by a restoring force of a diaphragm deformed by an electrostatic force. In the nozzle plate for ejecting ink in the chamber from the nozzle, the diameter of the nozzle decreases from the ink inflow side into which the ink in the liquid chamber flows to the ink ejection side in which the inflow ink is ejected, and Nozzle plate characterized by having a smooth round shape in cross section. 2. The ink has a diameter n at a position of 3/5 of the thickness from the end of the round shape portion to the end in the direction from the ink ejection side to the ink injection side. The nozzle plate according to claim 1, wherein the value x divided by the diameter N of the ejection portion is x (= n / N), and the value x is in the range of 1 ≦ x ≦ 1.7. 3. A plurality of nozzles, which communicate with a plurality of liquid chambers filled with ink, are formed, and the liquid changes due to a pressure change in the liquid chamber caused by a restoring force of a diaphragm deformed by an electrostatic force. In a method for manufacturing a nozzle plate in which ink in a room is ejected from the nozzles, an organic additive having an S element in the molecule is formed on the surface of the substrate by forming an electrically insulating film on a portion of the predetermined substrate that will be the nozzles Alternatively, after performing electroforming using a plating solution containing an organic additive having a benzene ring skeleton or an organic additive having a benzene ring skeleton, the electrical insulating film is removed, and the electrodeposited film is removed from the substrate. When the nozzle is formed, the diameter of the electrodeposited film is reduced and the diameter of the electrodeposited film is reduced from the ink inflow side into which the ink in the liquid chamber flows to the ink ejection side to eject the inflowing ink. , The method of manufacturing a nozzle plate, characterized in that the nozzle plate cross-sectional shape of the nozzle is formed into a smooth round shape. 4. The method of manufacturing a nozzle plate according to claim 3, wherein the surface of the nozzle plate on the ink ejection side is subjected to eutectoid plating of a predetermined water-repellent coating. .