JP2001010054A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent incomplete ejection due to a standing bubble by tapering an ejection nozzle toward an orifice such that the extension of tapered surface does not intersect the wall face of a supply nozzle between the orifice and the interface between a resin film and an adhesive layer. SOLUTION: On the side of an ink jet head being boded to a resin film 3, recesses 6 serving as liquid chambers 7 and grooves 4 serving as nozzles on the opposite sides thereof are formed at a predetermined interval and opening 5 serving as ejection nozzles 10, communicating with orifices 9 on the rear side (face 13) of the bonding face of the resin film 3, are made in the bottom face of the groove 4 while being tapered toward the orifice 9. Inclination of the extension of tapered surface of the ejection nozzles 10 is set at such an angle as it does not intersect the wall face of the nozzle 11 between the surface of the substrate 1 and the orifice 9. According to the structure, unnecessary bubbles in the nozzle 11 can be discharged smoothly and the generation of an inconvenient recess or a flaw on the nozzle wall can be prevented during ablation.

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 for joining a resin film having an opening and a groove to a substrate having discharge means via an adhesive layer. In particular, in an ink jet head in which the orifice and the discharging means are provided in a facing relationship to each other, and the liquid is discharged in a direction substantially perpendicular to the substrate, it is possible to prevent a defective discharge due to bubbles in the nozzle,
The present invention relates to an ink jet recording apparatus for improving reliability.

[0002]

2. Description of the Related Art There is known an ink jet head in which a groove serving as a nozzle and an opening serving as an orifice are provided in a resin film, and the film is adhered to a substrate having discharge means such as a heater. The following process can be considered as a relatively simple configuration of this manufacturing method. A material that can be ablated is selected as a resin film, and an adhesive is thinly coated on the film in advance to form an adhesive layer. Thereafter, an excimer laser is irradiated from the side of the adhesive layer to form an opening having a predetermined shape, a groove and a concave portion having a predetermined depth. The processing order may be groove → opening, opening → groove. In either procedure, the film can be formed by irradiating an opening serving as an orifice and a groove serving as a nozzle with an excimer laser from substantially the same direction without changing the angle between the film and the optical axis.
Finally, the substrate and the film are bonded so that the orifice and the heater face each other. Due to the bubbling force on the heater, the droplets are ejected in a direction substantially perpendicular to the substrate.

[0003] For stable droplet formation, smoothness of the inner surface of the nozzle is important. This is for facilitating discharge of unnecessary bubbles in the nozzle. If there is a concave portion where bubbles easily adhere to the nozzle wall or a concave portion where ink flow tends to be stagnant, the retention, coalescence and growth of bubbles proceed from that location, and the risk of defects due to bubble accumulation increases. In particular, in the case of an ink jet head using a heater as a discharge means, fine bubbles are generated around the heater at the time of bubbling of the heater, and these bubbles are united in the nozzle to easily cause a bubble pool which causes a discharge failure. Bubbles in the nozzle are not preferred to prevent refilling at any point, but in particular,
If bubbles accumulate on the surface of the nozzle surrounding the ejection means facing the orifice, there is a danger that the ejection force will be absorbed and the ejection of droplets will not be possible.

According to the study of the present inventors, the starting point of the bubble is often on the nozzle wall surface parallel to the direction of ink flow in the nozzle from the liquid chamber to the discharge nozzle. In order to avoid this, it is necessary to make the nozzle surface a smooth surface having no concave portion so that bubbles are not easily attached thereto. At the same time, it is preferable that the nozzle has a smooth throttle curved surface in the path from around the heater to the orifice so that the small bubbles generated in the nozzle are discharged to the outside together with the discharge of the droplet.
For example, HEWLETT-PACKARD C1823A
Like a cartridge, an electroformed orifice plate is used, and the discharge nozzle is provided with a smooth curved surface P5 whose taper angle decreases in the discharge direction (FIG. 5B), so that smooth discharge of bubbles is performed. It is also possible.

In the ink jet head having the structure shown in FIG. 5B, a nozzle wall 17 made of a photosensitive resist also serving as an adhesive layer is provided on a substrate 1, and an electroformed portion having an opening and an orifice and having no groove is provided. The orifice plate is joined. A curved surface such as P5 having a continuously changing curvature can be relatively easily formed by electroforming. However, instead of a large degree of freedom in the shape of the discharge nozzle, it is necessary to process the nozzle and the orifice by completely different manufacturing methods.

[0006]

However, FIG.
In the ink-jet head configured as shown in (b), the nozzle and the orifice need to be processed by completely different manufacturing methods instead of having a large degree of freedom in the shape of the discharge nozzle. Further, the method of forming an orifice and a nozzle in a resin film has the following restrictions. When an orifice is opened in a resin film by ablation processing, the taper angle of the surface to be processed is usually substantially constant from the laser incident side to the emission side, that is, the taper angle of the discharge nozzle is in the discharge direction. Therefore, in order to smoothly discharge bubbles from the nozzle, it is necessary to provide a nozzle shape that has not been defined before. Also, when processing both the groove and the opening on the same film, depending on how the projection patterns of both laser beams overlap, the side surface of the wall of the nozzle or the discharge nozzle may be damaged or bubbles may adhere. An easy depression is formed, and there is a risk that bubbles may coalesce and grow from this point.

Accordingly, the present invention solves the above-mentioned problems, and in an ink jet head that processes both an orifice opening and a nozzle groove in a resin film by ablation, a discharge failure due to bubbles in the nozzle is prevented, and high reliability is achieved. It is an object to provide an ink jet head.

[0008]

According to the present invention, in order to achieve the above object, an ink jet head is constructed as follows. That is, the ink jet head of the present invention is a resin film made of an abratable material and having a discharge nozzle formed by an opening serving as an orifice, and a supply nozzle communicating with the orifice and supplying ink formed by a groove. And a substrate having discharge energy generating means, wherein the resin film and the substrate are located at a position where the orifice and the discharge energy generating means face each other, so that the droplet is discharged in a direction substantially perpendicular to the substrate. An ink jet head joined through an adhesive layer, wherein the discharge nozzle has a taper angle θ whose cross-sectional area decreases toward the orifice, and an extension of the tapered surface of the discharge nozzle is the droplet. Between the interface between the resin film and the adhesive layer and the orifice in a cross section including the axis of the direction in which the liquid is discharged. Oite, it is characterized by not cross the wall or its extension line of the supply nozzle. Further, in the inkjet head of the present invention, an extension of the tapered surface of the discharge nozzle is an interface between the resin film and the adhesive layer,
Between the orifices, a configuration that does not intersect the wall surface of the supply nozzle or an extension thereof is provided in a cross section orthogonal to the direction of the axis of the ink flow in the nozzle. Further, in the inkjet head of the present invention, the extension of the tapered surface of the discharge nozzle does not intersect the wall surface of the supply nozzle or the extension thereof between the interface between the resin film and the adhesive layer and the orifice. When viewed from the side of the ejection energy generating means, the surface of the ejection nozzle is supplied in a section including an axis of the direction in which the droplet is ejected and a section including an axis orthogonal to the direction of the axis and the axis of the ink flow. It is characterized in that it is constituted by including the surface of the nozzle. Further, in the inkjet head of the present invention, the supply nozzle has a taper angle θn in which a cross-sectional area decreases in a direction away from the substrate, at least in a vicinity of a connection portion with the discharge nozzle, and is directed toward the orifice of the discharge nozzle. Θ <θn in relation to the taper angle θ at which the cross-sectional area decreases
It is characterized by that. Further, the inkjet head according to the present invention is characterized in that an outer periphery of the discharge nozzle and / or a corner of the nozzle at a connection portion with the supply nozzle has a substantially round shape of 2 μm or more. Further, the inkjet head of the present invention,
The discharge energy generating means is a heater.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With the above-described structure, the present invention can provide a nozzle structure in which unnecessary bubbles in a nozzle are smoothly discharged while the discharge nozzle has a constant taper angle. In addition, at the time of ablation processing, it is possible to prevent the occurrence of undesired depressions and scratches on the nozzle wall due to the overlapping of the projection patterns of the openings and grooves, and to prevent the risk of bubbles adhering inside the nozzles.

[0010]

Embodiments of the present invention will be described below.
In addition, if it is in line with the idea of the present invention, the embodiment is
The present invention is not limited to the embodiments and other specific shapes in this specification. For example, the orifice need not be limited to a circle, but may be a rectangle. The same applies to the nozzle.
ArF, X as means for ablation processing
It is also conceivable to use an eCl excimer laser or a double-wave YAG laser. Further, as the discharging means, a piezo element, an electrostatic actuator, or the like may be used instead of the heater.

Embodiment 1 FIG. 1 is a schematic view of a main part of an ink jet head according to Embodiment 1 of the present invention. FIG. 1A is a view of the resin film 3 as viewed upward, and FIG.
FIG. 2B is a view of the substrate 1 (back surface) viewed upward, and FIG.
Is an enlarged view of a groove. In FIGS. 1 and 2, a concave portion 6 serving as a liquid chamber 7 is arranged on the joining surface side of the resin film 3, and grooves 4 serving as nozzles are arranged at predetermined intervals on both sides thereof.
The groove 4 has substantially the same depth as the recess 6, and an opening 5 is provided on the bottom surface of the groove 4. The opening 5 communicates with the orifice on the back side (face surface 13) of the bonding surface of the film 3.
The substrate 1 has a heater serving as a discharge means and a supply port 12 for supplying ink to the liquid chamber. The film 3 and the substrate 1 are joined at a position where the orifice 9, the opening 5 and the heater 2 substantially face the front. The Z axis is the direction in which droplets are ejected, and the Y axis is the direction in which ink flows from the liquid chamber to the heater 2 through the nozzles. The X axis is a direction orthogonal to the Y and Z axes.

Next, the manufacturing process of the ink jet head of this embodiment will be described. The manufacturing process is performed according to the flow of FIG. 3A to 3D and 3E are cross sections orthogonal to the Y axis, that is, orthogonal to the direction of the ink flow axis. The resin film 3 uses 25 μm thick Upilex (trade name: Ube Industries) as a base material. First, a water-repellent film 16 is formed on one surface of the film 3. Next, the surface of the film 3 opposite to the water-repellent film is coated with a thermosetting epoxy resin that can be ablated as an adhesive to form a B-staged adhesive layer 8 of about 3 μm.
(B)). The surface of the adhesive layer 8 becomes a bonding surface with the substrate.

Next, in order to form an opening from the side of the adhesive layer 8, a circular image similar to the orifice is projected by an excimer laser. Processing is 1.3 J / cm ² / pulse at 1
Continuous irradiation was performed at 00 Hz. The adhesive layer on the incident surface is also ablated by the excimer laser. Thus, the opening 5 and the orifice 9 having a diameter of about 20 μm and having no burrs were formed (FIG. 3C). The taper angle θ caused by the laser attenuation was about 12 °. This value varies depending on the material and thickness of the resin film 3 and the adhesive layer 8, and the energy density on the incident surface of the excimer laser to be projected.

Next, an image of the groove is projected from the same direction as in FIG. Processing is 1.3 J / cm
Irradiation was carried out at 60 Hz for 100 pulses at ² / pulse (FIG. 3 (d)). As a result, a groove having a depth of 18 to 20 μm is formed. At the same time, the recess 6 is also processed. The taper angle of the wall of the groove was about 12 ° like the opening 5. The entrance side of the opening 5 provided earlier is cut off. Finally, the film 3 and the substrate 1 are aligned and overlapped so that the orifice 9 and the heater 2 face each other, heated to about 200 degrees by applying a heat pulse, and melt-bonded. The opening 5, which becomes the liquid chamber 7 and is not cut into the groove 4, forms a discharge nozzle 10.

Next, the features of this embodiment will be described with reference to FIG. FIG. 4 is a cross section including the Z axis and the X axis.

As shown in FIG. 4A, the inclination of the extension line L of the tapered surface of the discharge nozzle 10 is expressed by the taper angle θ of the discharge nozzle 10.
4 does not intersect with the wall surface Ln of the nozzle 11 between the surface of the substrate 1 and the orifice 9. As a result, the laser, the projection pattern, and the pattern for processing the nozzles at least around the discharge means except for the direction of the liquid chamber include the former in the latter.

When a nozzle and an orifice are formed in the order of opening and groove as shown in FIG. 3, when L and Ln intersect between the interface between the resin film 3 and the adhesive layer 8 and the orifice 9, FIG.
The shape is as shown in FIG. As a result, a minute depression 15 is generated on the nozzle wall. The depression at the corner does not contribute to the refilling of the ink due to the viscosity of the ink itself, and often serves as a starting point to which bubbles to be discharged from the nozzle adhere. In the configuration where L and Ln intersect on the substrate, FIG.
When processing is performed in the order of the opening and the groove in the reverse order of the above procedure, the outer peripheral portion of the projection pattern of the opening is blocked by the edge of the groove, and the orifice is distorted into a shape different from the projection pattern.

The most preferable configuration is that L and Ln do not intersect between the orifice 9 and the surface of the substrate 1. However, it is conceivable that L and Ln intersect in the layer of the adhesive layer 8, that is, between the interface between the film 3 and the adhesive layer 8 and the substrate 1. In this case, a dent is formed on the surface of the adhesive layer 8 immediately after the ablation process. However, if the material is such that the adhesive flows during bonding with the substrate, the dent is filled with the flowing surrounding adhesive. However, if the material system does not cause such a phenomenon that the dents are refilled, or if the refilling is not sufficiently performed, the same problem as the structure shown in FIG. 5A may occur. Therefore, in order to obtain the function to be achieved by the present embodiment, instead of using the adhesive layer surface, which is the exposed surface on the laser incident side, of the combined resin film of the adhesive layer and the base material as a reference, With reference to the interface between the resin film and the adhesive layer in the resin film from the exposed surface as a reference, between the reference surface and the orifice, the wall surface Ln of the nozzle 11 of the tapered surface of the discharge nozzle 10, or any extension line Need not intersect.

The structure shown in FIG.
As shown in (b), curved surfaces Cn and C may be provided at the corners of the nozzles 11 and at the corners of the connecting portions of the discharge nozzles 10 to make the discharge of bubbles more smooth. As long as the shape does not change in curvature, such as Cn and C, it can be formed by only slightly changing the excimer laser processing procedure in FIG. For example, in order to form Cn, in FIG. 3D, the focus of the projection pattern of the groove 4 may be processed away from the incident surface, in a defocused state, or with a reduced energy density of the laser. In order to form C, it is conceivable to reverse the processing order of the groove and the opening in FIG. 3 and project the processing pattern in a defocused state when processing the opening.

In the case of an ink jet recording apparatus based on water and ejecting an ink having a viscosity of 6 [mPa * s] or less, if the depth of the groove serving as a nozzle is 10 to 50 μm, both Cn and C are 2 μm or more. The present inventors have confirmed through experiments that the discharge of bubbles is smooth by adopting the substantially R shape. However, in order to stably obtain the structure of FIG.
As described above, the processing procedure is slightly more complicated than in FIG.

[Embodiment 2] Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6B is a diagram viewed from the same line of sight as FIG. FIG. 6 shows an example in which the surface L of the discharge nozzle 10 includes the surface Ln of the nozzle 11 in a cross section including the X axis and the Z axis except for the liquid chamber side when viewed from the heater, so that the two do not intersect with the substrate 1. .

Embodiment 3 Embodiment 3 of the present invention will be described with reference to FIG. In the present embodiment, the taper angle θn7 of the nozzle 11 is
7> θ7. Specifically, the energy density of the excimer laser was 1.3 J / cm ² / pulse and the taper angle θ7 = 12 ° when the opening serving as the discharge nozzle was processed, while the energy density was 0.7 J during the groove processing. /
cm ² / pulse. As a result, θn7 = 20 °
I got

In the present embodiment, the taper with respect to the Z axis is reduced from the heater 2 toward the orifice 9 so that
This has the same effect as the plane P5 in which the curvature gradually decreases as shown in FIG. However, if θn7 is large, there is a risk that a starting point of a bubble pool similar to the depression 15 in FIG. In order to avoid this and to obtain a foam discharging effect, a water-based viscosity of 6 [mPa *
s] or less, it is preferable to satisfy the range of 5 ° <θ7 <θn7 <30 °.

[0024]

As described above, according to the present invention, it is possible to obtain a nozzle structure in which unnecessary bubbles in the nozzle are smoothly discharged.
Unnecessary dents and scratches on the nozzle wall due to the overlapping of the projection patterns of the openings and grooves can be prevented, and the risk of bubbles adhering inside the nozzles can be prevented. Therefore, according to the present invention, in an ink jet head that processes both an orifice opening and a nozzle groove in a resin film by ablation, it is possible to prevent a discharge failure due to bubbles in the nozzle and obtain a highly reliable ink jet head.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an inkjet head used in the present invention.

FIG. 2 is a diagram illustrating a configuration of an inkjet head used in the present invention.

FIG. 3 is a view for explaining a process flow of Example 1 in the present invention.

FIG. 4 is a view for explaining a process flow of Example 1 in the present invention.

FIG. 5 illustrates a relationship with a comparative example.

FIG. 6 is a diagram illustrating a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a third embodiment of the present invention.

[Explanation of symbols]

 1: substrate 2: heater 3: resin film 4: groove 5: opening 6: recess 7: liquid chamber 8: adhesive layer 9: orifice 10: discharge nozzle 11: nozzle 12: supply port 13: face surface 14: water-repellent film 15: depression 16: electroformed orifice plate 17: resist nozzle wall

Claims (6)

[Claims] 1. A resin film comprising a dischargeable nozzle formed of an ablative material and formed by an opening serving as an orifice, a supply nozzle communicating with the orifice and formed by a groove for supplying ink, and a discharge energy. A substrate having generating means, wherein the resin film and the substrate are located at a position where the orifice and the discharge energy generating means face each other, and an adhesive layer is formed so that droplets are discharged in a direction substantially perpendicular to the substrate. An ink jet head having a taper angle θ in which a cross-sectional area decreases toward the orifice, and an extension of the tapered surface of the discharge nozzle is directed in a direction in which the droplet is discharged. In the cross section including the axis of, between the interface between the resin film and the adhesive layer and the orifice, the wall of the supply nozzle Or the ink jet head, characterized in that does not intersect with the extension line thereof. 2. A configuration in which an extension of a tapered surface of the discharge nozzle does not intersect a wall surface of the supply nozzle or an extension thereof between an interface between the resin film and the adhesive layer and the orifice. The ink jet head according to claim 1, wherein the ink jet head has a cross section orthogonal to the direction of the axis of the ink flow in the nozzle. 3. A configuration in which an extension of a tapered surface of the discharge nozzle does not intersect a wall surface of the supply nozzle or an extension thereof between an interface between the resin film and the adhesive layer and the orifice. When viewed from the discharge energy generation means side, in the cross section including the axis of the direction in which the droplet is discharged, and in the cross section including the axis orthogonal to the direction of the axis and the axis of the ink flow, the surface of the discharge nozzle corresponds to the surface of the supply nozzle. The ink-jet head according to claim 1, wherein the ink-jet head is configured by being included. 4. The supply nozzle has a taper angle .theta.n in which a cross-sectional area decreases in a direction away from the substrate, at least in the vicinity of a connection portion with the discharge nozzle, and has a cross-sectional area toward the orifice of the discharge nozzle. The inkjet head according to claim 1, wherein θ <θn is set in relation to the decreasing taper angle θ. 5. An outer periphery of the discharge nozzle at a connection portion with the supply nozzle, and / or a corner of the nozzle,
The inkjet head according to any one of claims 1 to 3, wherein the ink jet head has a substantially round shape of 2 m or more. 6. The ink jet head according to claim 1, wherein the discharge energy generating means is a heater.