JPH10193605A - Ink jet head and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a problem such as squeeze-out of adhesive or insufficient adhesive force at the time of adhering a diaphragm by forming a liquid chamber component by an electroforming method, and forming the liquid chamber width in the component narrow at a near part for adhering the diaphragm and wide at a remote part from the diaphragm. SOLUTION: An electroforming liquid chamber member 10 formed by an electroforming method has a liquid chamber 11, a manifold 12 and an ink supply port 13 on a base plate 2, and a diaphragm for giving vibration for discharging ink in the chamber 11 is adhered to its upper surface (adhesive surface) 3. In this case, when a width of the chamber 11 at the plate 2 side is indicated by b1 and a width at the surface 3 side is indicated by b2, it is formed to satisfy b1>b2. Thus, a thickness of a liquid chamber wall 14 is formed thick near the surface 3, an area of the surface 3 is formed wide, and hence a problem of adhesive fault such as squeeze-out of the adhesive or insufficient adhesive force at the time of adhering the diaphragm is eliminated. And, sufficient ink amount of the degree that printing image quality is not deteriorated can be stored in the chamber 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head used in an apparatus such as a printer for forming an ink image on a medium such as recording paper by discharging ink droplets, and a method of manufacturing the same, and more particularly, to a main part constituting the ink jet head. And a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional piezoelectric ink jet head has a piezoelectric element for generating a driving force by an electrostrictive effect for discharging ink, a diaphragm for transmitting the driving force generated by the piezoelectric element to a liquid chamber, and an ink flow path. It comprises a liquid chamber component having a liquid chamber also serving as a pressurizing chamber, and a nozzle plate having ink discharge holes (hereinafter referred to as nozzles) for discharging ink pressurized in the liquid chamber.

FIG. 4 shows an example of a conventional piezoelectric ink jet head. The liquid chamber component 1 has a large number of deep groove-shaped liquid chambers 11 which also serve as ink flow paths and ink pressurizing chambers. Each liquid chamber 11 corresponds to a nozzle 21 opened in the nozzle plate 20, and is configured such that one nozzle 21 is arranged in one liquid chamber 11. Therefore, in order to increase the resolution of the ink jet head, it is necessary to reduce the distance between the liquid chambers 11 formed in the liquid chamber component 1. Note that the nozzle plate 20 and the liquid chamber component 1 are usually joined with an adhesive.

[0004] The diaphragm 30 is usually formed with a protruding groove called an island 31 projecting about 20 µm in a thin plate of about 3 to 5 µm. The islands 31 are used to reliably transmit the distortion to the liquid chamber 11 when the piezoelectric element 40 expands and contracts due to the electrostriction effect. Therefore, the islands 31 are arranged so as to overlap the corresponding liquid chambers 11 and piezoelectric elements 40. The liquid chamber component 1 and the diaphragm 30 are joined with an adhesive.

The piezoelectric elements 40 correspond to the respective liquid chambers 11 of the liquid chamber component 1 and are separated so as not to affect the other liquid chambers 11. These separated piezoelectric elements 40 are fixed on a base 50. Generally, for manufacturing reasons, a step is first taken in which the piezoelectric element 40 that has not been separated is first bonded to the base 50 with an adhesive and then only the piezoelectric element 40 is separated by cutting. In a state where the piezoelectric element 40 and the base 50 are joined, the piezoelectric element 40 and the island 31 formed on the diaphragm 30 corresponding thereto are joined with an adhesive.

As a conventional method of forming a liquid chamber component of a piezoelectric ink jet head, a method of molding an organic material such as an epox by an injection molding method has been generally used. In addition, there is also a molding method using a processing method called a powder injection molding method in which an oxide such as ZrO ₂ is molded by injection molding instead of an organic material. These molding methods always require a mold. However, since a very large pressure is applied when a material is injected into a mold, it is difficult to make the mold into a fine shape, and these methods are not suitable for those having a fine shape.

As a processing method suitable for forming a fine shape, there is an etching method. By using etching, it is possible to easily pattern a metal plate having a thickness of about several hundred μm into a groove shape. However, even in this method, the groove width equivalent to the film thickness is the limit in terms of increasing the density, and is not so effective. Further, in the case of etching, the groove penetrates, so that a plate-like material must be bonded to one of the surfaces of the metal plate to be used as a liquid chamber component, which complicates the process.

As described above, conventionally, the liquid chamber component and the diaphragm are formed separately and are joined by an adhesive or the like. The point required in this joining step is to minimize the amount of adhesive so that the adhesive does not protrude into the liquid chamber, and that the ink in each liquid chamber is in contact with the other liquid chamber. It must be firmly adhered so as not to conduct. These requirements become more difficult as the inkjet head advances in the direction of higher density. This is because the bonding area becomes very small due to the high density.

[0009]

In recent years, there has been a demand for a higher density of 180 dots per inch (hereinafter referred to as 180 dpi) or more. Naturally, the distance between the liquid chambers and the distance between the nozzles are also required to be equivalent to 180 dpi. 180
The interval corresponding to dpi means that the liquid chamber and the nozzle are formed at an interval of 141 μm. In the liquid chamber, it means that a wall partitioning between the liquid chambers is formed between 141 μm. When the width of the liquid chamber and the thickness of the wall are in a ratio of 1: 1, the width of the liquid chamber is 70.5 μm and the thickness of the wall is 70.5 μm.
m.

On the other hand, even when the density of the liquid chamber is reduced and the width of the liquid chamber is reduced, a sufficient amount of ink to be ejected must be secured in order to obtain a sufficient print quality. Therefore, it is necessary to increase the volume of the liquid chamber,
Inevitably, it is required to increase the height of the liquid chamber. For these reasons, an ink jet head capable of high-density printing requires a liquid chamber having a narrow liquid chamber width and a high liquid chamber height. Therefore, a forming method capable of forming a liquid chamber having such a shape is required.

In the conventional ink jet head, the liquid chamber component and the diaphragm are formed separately as described above,
Apply adhesive to the upper flat surface of the wall that separates the liquid chamber of the liquid chamber part,
Bonding with the diaphragm was performed. However, as the density of ink jet heads increases, bonding with an adhesive becomes more difficult, and it is almost impossible to apply the adhesive stably at a density exceeding 180 dpi. In this case, the problem that the surface becomes very weak occurs.

[0012]

According to the present invention, in order to solve the above-mentioned problems, a liquid chamber component is formed by electroforming, and a liquid chamber formed in the liquid chamber component has a liquid chamber width of a diaphragm. The structure was narrow in the vicinity of the substrate to be bonded and wide in the portion far from the diaphragm. That is, when attention is paid to the wall partitioning the liquid chamber, the portion near the diaphragm is thick, and the portion far from the diaphragm is thin, so that the bonding area with the diaphragm is large.

[0013]

FIG. 1 is a diagram showing a liquid chamber component of an ink jet head according to the present invention. FIG. 1 is a diagram viewed from the side where the diaphragm is bonded to facilitate understanding of the structure of the present invention. An electroforming liquid chamber member 10 is formed on the substrate 2 by electroforming. The electroforming liquid chamber member 10 forms a liquid chamber 11, a manifold 12, and an ink supply port 13. The upper surface of the electroforming liquid chamber member 10 has an adhesive surface 3 with a diaphragm having a function of giving vibration to discharge ink in the liquid chamber 11. Has a role. The liquid chamber 11 shown here serves as a pressurizing chamber for ink, the manifold 12 serves to distribute ink to each liquid chamber 11, and the ink supply port 13 serves to supply ink to the ink jet head.

The most distinctive feature of the liquid chamber component of the ink jet head of the present invention is that the cross section of the liquid chamber 11 is located on the platform. As shown in the figure, if the width of the liquid chamber 1 on the substrate 2 side is b1, and the width of the liquid surface 1 on the bonding surface 3 side is b2,
The structure is b1> b2.

Normally, it can be easily inferred from the drawings that the distance p between the liquid chambers 11 is reduced when the density of the ink jet head is increased. As the distance p between the liquid chambers decreases, the width b1 of the liquid chambers also needs to be reduced. However, in order to maintain excellent print image quality, it is better that the volume of the liquid chamber 11 is large, and for that purpose, it is desirable that the ink liquid chamber width b1 be as large as possible. For these reasons, conventionally, when the density is to be increased, the thickness of the liquid chamber wall 14, which is a wall partitioning the liquid chamber 11, has been reduced to increase the capacity of the liquid chamber 11 as much as possible.

However, by making the liquid chamber wall 14 thinner, the adhesive area of the adhesive in the step of bonding with the diaphragm is reduced, so that the adhesive protrudes into the liquid chamber or the head due to insufficient adhesive force. There have been problems such as a decrease in reliability.

In the liquid chamber component structure of the ink jet head according to the present invention, as shown in FIG. 1, the thickness of the liquid chamber wall 14 is increased near the bonding surface 3 with the diaphragm, so that the area of the bonding surface 3 is increased. As a result, all of the above-mentioned problems could be solved.

Hereinafter, the dimensions of each part of the liquid chamber component of the ink jet head according to the present invention will be described in more detail. Here, a case of a high-density inkjet head capable of printing at 180 dpi will be described as an example. In the case of 180 dpi, the distance p between the liquid chambers 11 is 141 μm. Here, from the desire to increase the volume of the liquid chamber 11 as much as possible, the liquid chamber width (substrate 2 side) b1 was set to 100 μm. as a result,
The liquid chamber wall width (substrate 2 side) b3 is 41 μm. In a conventional liquid chamber component, an adhesive must be applied within the width of 41 μm and adhered to the diaphragm. Therefore, the method of applying the adhesive is limited, and the bonding process is extremely difficult.

However, in the liquid chamber component of the present invention, the relationship between the liquid chamber width and the liquid chamber wall width is reversed in the vicinity of the bonding surface 3 with the diaphragm. On the bonding surface 3 side, the liquid chamber width b2 was 41 μm, and the liquid chamber wall width b4 was 100 μm. As a result, 100μ
An adhesive width of m width can be ensured, and in this case, an adhesive application method such as a screen printing method, an octopus printing method, or a letterpress printing method can be used, and the bonding process becomes very easy.

In the case of a component having a three-dimensional shape such as a liquid chamber component of an ink jet head of the present invention, a conventional manufacturing method such as an injection molding method or an etching method cannot be used. Therefore, in the present invention, a method of forming a liquid chamber component by combining photolithography and electroforming is used. Hereinafter, a method for manufacturing a liquid chamber component of an inkjet head according to the present invention will be described with reference to examples.

FIG. 3 is a diagram of a substrate used for manufacturing a liquid chamber component of an ink jet head according to the present invention. The substrate 2 is made of a light-transmitting transparent material. In this embodiment, a glass substrate having a thickness of 0.4 mm was used. On the substrate 2, an electrode film 4 made of a conductive material and an opaque material that blocks light is patterned into a desired shape.

The method of patterning the electrode film 4 in this embodiment will be described below. First, a Cr film was formed as the electrode film 4 on the glass substrate 2 to a thickness of 0.1 μm by a sputtering method. The film formation conditions were 4 at an Ar gas pressure of 0.01 torr.
The conditions were that RF power of 50 W was applied and sputtering was performed for 4 minutes.

Thereafter, a photosensitive resist was first coated on the Cr film by spin coating. As a photosensitive resist, a positive resist called AZ-4620 manufactured by DuPont was used and spin-coated at 4000 rpm for 30 seconds to coat it with a thickness of 6 μm.

Next, the photosensitive resist AZ-4620 is patterned using an exposure mask having a desired liquid chamber shape. Since AZ-4620 is a positive resist, a mask in which a desired liquid chamber shape is drawn with a Cr film was used as an exposure mask used here. The exposure of AZ-4620 was performed under the condition of 100 mJ / cm ² , and the development was performed by immersing in a dedicated developer at 25 ° C. for 1 minute.

After that, in a state where AZ-4620 is patterned on the Cr film, the Cr film is formed by wet etching.
The film was patterned. As an etching solution, an aqueous solution in which 16 cc of perchloric acid and 32 g of ceric ammonium nitrate were mixed in 800 cc of water was used. At this time, the wet etching method was an immersion method, and was immersed in the etching solution for about 1 minute.

Finally, the substrate is immersed in acetone and AZ
The −4620 is peeled off, and the patterning of the Cr film is completed.

FIG. 2 is a view showing a method of manufacturing a liquid chamber component of an ink jet head according to the present invention. First, as shown in FIG. 2A, a first resist 5 which is a photosensitive resin is coated on a transparent substrate 2 in which an electrode film 4 is patterned into a desired shape, and exposure is performed from the substrate 2 side. Such a method of exposing the photosensitive resin through the substrate 2 is generally called a back exposure method.

In this embodiment, a negative type resist called JSR-30 manufactured by Nippon Synthetic Rubber Co., Ltd. was used as the first resist 5. The resist was coated by a spin coating method. In this example, the substrate was rotated at 1000 rpm for 10 seconds to form a coating having a thickness of 60 μm. After coating the first resist 5, the substrate 2
Exposure is performed from the side. In this step, the exposure amount is 400 m
J / cm ² .

In the next step shown in FIG. 2B, a second resist 6 is coated on the first resist 5 and exposure is performed using an exposure mask 7. This exposure method is a commonly used exposure method, but is referred to as a front exposure method here as opposed to a back exposure method.

The second resist 6 was made of the same material as the first resist 5, and was coated by spin coating. The coating condition is 10 at 4000 rpm.
The coating was performed with a thickness of 20 μm under these conditions. After coating the second resist 6, front exposure is performed. In this embodiment, 200 mJ / c
Exposure at m ² . The exposure mask 7 used in the present embodiment
Is drawn with a shape different from the shape of the liquid chamber of the electrode film 4 patterned on the substrate 2, so that a liquid chamber having a three-dimensional shape, which is a feature of the present invention, can be formed.

In the step of FIG. 2C, the first resist 5 and the second resist 6 are simultaneously developed. In the present embodiment, development was carried out by immersion in a dedicated developer at 40 ° C. for 10 minutes.

Thereafter, as shown in FIG. 2D, electroforming was performed using the electrode film 4 serving also as a mask during back exposure as an electrode. In the manufacturing method of the present invention, since the electrode film 4 simultaneously functions as a mask and an electrode, it is also a feature of the manufacturing method of the present invention that the electrode film 4 is patterned in a continuous shape on a plane. One. By doing so, the step of forming an electrode can be omitted. As the electroforming method, a Ni electroforming method generally used widely was used. For this Ni film formation, a treatment bath having the following composition was used: water 5 L nickel sulfamate 1650 g nickel chloride 150 g boric acid 225 g sodium lauryl sulfate 5 g. Treatment bath temperature is 60 ° C, current density is 50m
A / cm ² , and the stirring speed of the bath was 1 L / min. The electroforming solution chamber member 10 was formed by this electroforming method.

Next, after cutting the AA portion shown in FIG. 2D in the direction of the arrow, finally, the first resist and the second resist 6 (the first resist is a The liquid chamber component of the ink jet head of the present invention is completed by dissolving (which is hidden from the surface of the casting liquid chamber member 10 and cannot be seen from the surface) with a stripping solution dedicated to the present resist.

[0034]

According to the liquid chamber component of the present invention, since the liquid chamber wall partitioning the liquid chamber is thick near the surface where the diaphragm is bonded, the adhesive protrudes and the adhesive strength is insufficient during the bonding process with the diaphragm. It is possible to solve the problem of poor adhesion such as the above. On the other hand, the liquid chamber wall is thin near the substrate, and the liquid chamber volume is increased. Therefore, a sufficient amount of ink that does not deteriorate the print quality can be stored in the liquid chamber. Since the conflicting problems can be solved at the same time as described above, it is possible to cope with an increase in the density of the ink jet head.

According to the method for manufacturing a liquid chamber component of the present invention, a liquid chamber (or liquid chamber) having a three-dimensional shape like the liquid chamber component of the present invention, which cannot be formed by the conventional injection molding method or etching method. Wall) could be easily formed. In addition, the manufacturing method of the present invention uses a photolithography technique generally used in the field of LSI, and has a very high accuracy as compared with the conventional method. Therefore, a high-density inkjet head of 180 dpi or more can be manufactured with a sufficient margin.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a liquid chamber component of an ink jet head of the present invention.

FIG. 2 is a diagram illustrating a method of manufacturing a liquid chamber component of an inkjet head according to the present invention.

FIG. 3 is a perspective view showing a substrate used for manufacturing a liquid chamber component of the inkjet head of the present invention.

FIG. 4 is a diagram showing a component configuration of a conventional inkjet head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 liquid chamber component 2 substrate 3 bonding surface 4 electrode film 5 first resist 6 second resist 7 exposure mask 10 electroforming liquid chamber member 11 liquid chamber 12 manifold 13 ink supply port 14 liquid chamber wall 20 nozzle plate 21 nozzle Reference Signs List 30 diaphragm 31 island 40 piezoelectric element 50 base

Claims (2)

[Claims] A liquid chamber component having a liquid chamber for storing and pressurizing ink, a nozzle for discharging the ink pressurized in the liquid chamber, and a liquid chamber component joined to the liquid chamber component and provided inside the liquid chamber. In a piezoelectric ink-jet head including a diaphragm serving as a diaphragm for pressurizing ink and a piezoelectric element which obtains a driving force by an electrostriction effect and vibrates the diaphragm, the liquid chamber component is formed by electroforming. An ink jet head having a liquid chamber formed and having a narrow cross section in the vicinity of the diaphragm and a wide cross section in a portion far from the diaphragm. 2. A liquid chamber component having a liquid chamber for storing and pressurizing ink, a nozzle for discharging the ink pressurized in the liquid chamber, and a liquid chamber component joined to the liquid chamber component and provided inside the liquid chamber. In a method for manufacturing a piezoelectric ink jet head comprising a diaphragm serving as a diaphragm for pressurizing ink and a piezoelectric element for obtaining a driving force by an electrostrictive effect and vibrating the diaphragm, the liquid chamber component is made of a conductive material. Coating a first photosensitive resin material on the substrate on which the conductive film is formed, and exposing to a desired shape; coating a second photosensitive resin material on the first photosensitive resin material; Exposing to a desired shape; simultaneously developing the first photosensitive resin material and the second photosensitive resin material; performing electroforming by energizing the conductive film; The first photosensitive tree A method of manufacturing an ink jet head, characterized in that it is formed from a material and step of separating the second photosensitive resin material.