JP2001063037A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet head in which deterioration of image quality due to swelling of ink is suppressed by sandwiching a fluid resistance layer of photosensitive resin between two members of a material other than photosensitive resin thereby forming a fluid resistance part of the ink jet head. SOLUTION: A substrate 11 is held on a heat supporting member, i.e., a spacer member 21, and a PCB substrate having a head drive IC disposed in the spacer member 21 is connected with each piezoelectric element 12 of a drive unit 1 through an FPC cable 22 bonded to each electrode pattern 14, 15. A liquid chamber unit 2 is disposed thereon and the fluid resistance part thereof is formed by sandwiching a fluid resistance layer 26 of photosensitive resin, i.e., the sidewall part, between members of a material other than photosensitive resin, i.e., a diaphragm 23 and a liquid chamber lower plate 25, thus forming a channel.

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, and more particularly to an ink jet head having a fluid resistance portion.

[0002]

2. Description of the Related Art An ink-jet head in an ink-jet recording apparatus used as an image forming apparatus (image recording apparatus) such as a printer, a facsimile, a copying machine, a plotter, etc. has a nozzle for discharging ink droplets and a pressurized liquid communicating with the nozzle. A chamber (also referred to as a pressure chamber, a discharge chamber, a liquid chamber, an ink chamber, an ink flow path, etc.) and actuator means (energy generating means) for generating energy for pressurizing the ink in the discharge chamber. By driving the actuator means, the ink in the ejection chamber is pressurized to eject ink droplets from the nozzles.

[0003] There are several types of actuators depending on the type of actuator means for ejecting ink droplets (recording liquid). For example, as described in Japanese Patent Application Laid-Open No. 10-100401, a part of the wall of the liquid chamber is formed as a thin diaphragm, and a piezoelectric element as an electromechanical conversion element is disposed corresponding to the thin diaphragm to apply voltage. A piezo system that discharges ink droplets by changing the pressure in the liquid chamber by deforming the diaphragm by deformation of the piezoelectric element that accompanies it. A heating element is arranged inside the liquid chamber, and a heating element is energized. In general, a bubble jet type in which bubbles are generated by heating the ink and ink droplets are ejected by the pressure of the bubbles is well known.

Further, as described in, for example, Japanese Patent Application Laid-Open No. 2-289351, a vibration plate forming a wall surface of a liquid chamber, and individual electrodes outside the liquid chamber disposed opposite to the vibration plate are provided. An electrostatic type in which the diaphragm is deformed by an electrostatic force generated by applying an electric field between the diaphragm and the electrode, and ink droplets are ejected from nozzles by changing the pressure / volume in the liquid chamber. Has also been proposed.

With the demand for high-speed and high-quality image recording apparatuses, it is necessary to increase the degree of integration of the nozzles of the ink jet head and to reduce the diameter of the nozzles. For this reason, it is indispensable to improve the degree of integration of the liquid chamber structure and to make the fluid resistance portion finer to balance fluidly.

However, on the other hand, if the flying ink droplet volume is not ensured, the image quality deteriorates. Therefore, a pressurized liquid chamber or an ink liquid chamber for supplying ink to the pressurized liquid chamber (this is called a “common liquid chamber”). , "Common ink flow path", "common ink liquid chamber", etc.).
Therefore, securing the volume of the liquid chamber by increasing the pitch in the nozzle arrangement direction causes a reduction in the degree of integration, so that the volume in the liquid chamber volume is increased by increasing the thickness in the direction perpendicular to the nozzle arrangement direction, mainly in the thickness direction. We are trying to secure them.

Therefore, the liquid chamber portion needs a thin fluid resistance portion serving as an ink supply path between the common liquid chamber and the pressurized liquid chamber, and a thick pressurized liquid chamber and a common liquid chamber. In order to form these arbitrarily, various ink jet heads have been proposed in which thin layers such as a metal plate or a film-shaped photosensitive resin layer (dry film resist) are laminated in the thickness direction to form an ink flow path. Have been.

For example, as described in JP-A-10-71722, a vibration plate, a pressurized liquid chamber, and a pressurized liquid chamber are communicated on an actuator unit in which a laminated piezoelectric element is bonded on a substrate. And a liquid chamber unit formed by laminating and joining a liquid chamber forming member made of a film-shaped photosensitive resin forming a common liquid chamber to be formed and a nozzle plate having a nozzle communicating with the pressurized liquid chamber. . There is also known a photosensitive resin in which an ink flow path including a liquid chamber is formed by one layer.

[0009]

However, when the liquid chamber is formed of a film-like photosensitive resin layer or a laminate thereof,
However, since the dry film has water absorbency, the Young's modulus is reduced by the swelling of the ink, the rigidity of the entire liquid chamber is further reduced, the mutual interference between the channels is reduced, and the discharge efficiency is reduced. Therefore, there is a difference in the size and speed of the flying ink droplets immediately after the start of printing and after long use, and there is a problem that a large difference in image quality occurs.

The present invention has been made in view of the above points, and has as its object to provide an ink jet head capable of obtaining stable image quality over time.

In order to solve the above-mentioned problems, an ink-jet head according to the present invention comprises a fluid resistance portion for supplying ink to a liquid chamber to which a nozzle for discharging ink droplets communicates, and a fluid resistance layer made of a photosensitive resin. This is a configuration formed by being sandwiched between two members made of a material other than resin.

Here, the fluid resistance layer can be formed of a film-shaped photosensitive resin or a liquid photosensitive resin. Further, one member sandwiching the fluid resistance layer may be a diaphragm forming the wall surface of the liquid chamber. Further, it is preferable to apply an adhesion improving agent to at least one of the members sandwiching the fluid resistance layer. Furthermore, it is preferable to form an oxide film on the surface of at least one of the members sandwiching the fluid resistance layer.

Further, the fluid resistance layer may have a multilayer structure. In this case, it is preferable that a photosensitive resin layer for forming the fluid resistance layer is formed on each of the members sandwiching the fluid resistance layer, and the photosensitive resin layers are joined to each other.

It is preferable that the thickness of the fluid resistance layer does not exceed 50 μm, and the variation of the thickness of the fluid resistance layer is ±
Preferably it does not exceed 5 μm.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view showing an example of an inkjet head to which the present invention is applied, and FIG.
FIG. 3 is an enlarged cross-sectional view of a main part of the head in the inter-row direction, and FIG. 3 is an enlarged cross-sectional view of a main part of the head in the inter-channel direction.

This ink jet head includes a drive unit 1, a liquid chamber unit 2, and a head cover 3. The drive unit 1 has a plurality of laminated piezoelectric elements 12 joined and arranged in two rows on an insulating substrate 11 made of ceramic, glass epoxy resin or the like, and surrounds the periphery of the laminated piezoelectric elements 12 in each row. The frame member 13 as a liquid chamber support member is joined. Further, a common electrode pattern 14 and an individual electrode pattern 15 are provided on the substrate 11,
These common electrode pattern 14 and individual electrode pattern 1
Numerals 5 are connected to end electrodes 17, 18 in which the internal electrodes of the piezoelectric element 12 are alternately connected via a conductive adhesive 16. The common electrode pattern 14 is electrically connected to each other by filling a conductive adhesive in a hole 19 provided in the frame member 13.

The substrate 11 is supported and held on a spacer member (head holder) 21 serving as a head support member.
A PCB substrate having C and the like and each piezoelectric element 12 of the drive unit 1 are connected via an FPC cable 22 joined to each of the electrode patterns 14 and 15.

The liquid chamber unit 2 includes a vibration plate 23 made of a thin film of metal or resin, a liquid chamber lower plate 24 and a liquid chamber upper plate 25 made of a laminated metal plate constituting a liquid chamber partition member.
A fluid resistance layer 26 made of a film-shaped photosensitive resin and a nozzle plate 28 made of a metal, a resin, or the like in which the nozzle holes 27 are formed are sequentially laminated, and are formed by heat fusion.

The nozzle hole 2 is formed by these members.
7, common ink chambers 32, 32 located on both sides of the pressurized liquid chamber 31, and a fluid resistance unit for supplying ink from the common liquid chamber 32 to the pressurized liquid chamber 31. 3
3, 33 are formed. Therefore, the fluid resistance part 33
Is a liquid member which is a member made of a material other than the photosensitive resin, like the diaphragm 23 which is a member made of a material other than the photosensitive resin, with the fluid resistance layer 26 made of the photosensitive resin as a side wall. A flow path is formed between the lower chamber plate 25 and the lower chamber plate 25.

The nozzle cover (head cover) 3 is formed in a box shape to cover the peripheral portion of the nozzle plate 28 and the side surface of the head. An opening is formed corresponding to the nozzle plate 28, and the peripheral portion of the nozzle plate 28 is formed. Is bonded with an adhesive. Note that a water-repellent film 29 is formed on the surface of the nozzle plate 28.

In order to supply ink from an ink cartridge (not shown) to the liquid chamber, ink supply holes 35 to 38 are provided in the spacer member 21, the substrate 11, the frame member 13 and the vibration plate 21, respectively.
Is provided.

Next, a process for assembling the liquid chamber unit 2 will be described with reference to FIGS. First, a member in which the fluid resistance layer 26 made of a photosensitive resin is formed on the vibration plate 23 is manufactured as follows. That is, FIG.
For example, as shown in FIG.
After manufacturing a diaphragm 23 in which a polyimide film is laminated on a US substrate, a negative dry film resist 41 which is a photosensitive resin is laminated by heat and pressure as shown in FIG. The thickness of this dry film resist is, for example, about 20 to 50 μm.

Next, as shown in FIG. 3C, a pattern (a black portion is light shielding and a white portion is light transmitting) in accordance with the shape of the ink flow path (the shape of the fluid resistance portion 33) is shown. The exposed portion of the dry film resist 41 is cured by performing ultraviolet (UV) light exposure using a photomask 42 having the photomask 42. As a result, the dry film resist 41 has a cured region (exposed portion) 41a as a solvent insolubilized region and an uncured region (unexposed portion) 41b as a solvent solubilized region, as shown in FIG.

Therefore, as shown in FIG. 2E, the unexposed portion 41 is developed by using a solvent capable of removing the unexposed portion.
b, the exposed portion 41a is left, and the fluid resistive layer is formed of a photosensitive resin having a predetermined pattern formed in the exposed portion (cured region) 41a by drying and main-curing again with ultraviolet light and heat. 26 is formed.

At this time, the planar shape of the fluid resistance layer 26 made of a dry film as viewed from the nozzle surface is, as shown in FIG. 6, a part to be the fluid resistance part 33, a part to be the pressurized liquid chamber 31, and the common liquid. The chamber 32 has an open shape.

Next, as shown in FIG. 5 (a), a liquid chamber lower plate 25 made of a plate material having high rigidity such as SUS is laminated on a fluid resistance layer 26 made of a dry film, and then pressurized and fully cured. Heating is performed at a higher temperature than in the case of and bonding is performed. Then, as shown in FIG. 3B, the liquid chamber upper plate 24 and the nozzle plate 28 are joined to each other with epoxy or polyimide adhesive to form the liquid chamber unit 2.
To form

Next, a second embodiment of the present invention will be described. In this embodiment, the fluid resistance layer 26 in the above embodiment is formed by using a liquid photosensitive resin, and the other configuration is the same as the above embodiment. Therefore, FIG.
A manufacturing process of the liquid chamber unit 2 in this embodiment will be described with reference to FIG.

That is, as shown in FIG. 7A, for example, a diaphragm 23 in which a polyimide film is laminated on an etched SUS substrate is manufactured, and then a photosensitive polyimide adhesive is formed as shown in FIG. 7B. A negative resist 51 as an agent is uniformly applied by a spin coater. Pre-bake and coat each time when applying multiple coats to ensure thickness. The thickness of the resist is applied to be twice the target thickness in consideration of the fact that the film thickness is finally halved in the curing step.

Next, as shown in FIG. 3C, a pattern (in FIG. 3, a black portion is light shielding and a white portion is light transmitting) according to the shape of the ink flow path (the shape of the fluid resistance portion 33). The exposed portion of the resist 51 is cured by exposure to ultraviolet light (UV light) using a photomask 42 having the same, and heat treatment is performed at 150 ° C. As a result, the resist 51 has a cured region (exposed portion) 51a that is a solvent insolubilized region and an uncured region (unexposed portion) 51b that is a solvent solubilized region, as shown in FIG.

Therefore, as shown in FIG. 2E, the unexposed portion 51 is developed by using a solvent capable of removing the unexposed portion.
b, the exposed portion 51a is left and cured by heating at 250 ° C. or more in a nitrogen atmosphere to form a fluid resistance layer made of a photosensitive resin having a predetermined pattern formed in the exposed portion (cured region) 51a. 26 is formed.

Next, as shown in FIG. 5A, the SU is placed on the fluid resistance layer 26 made of a dry film.
A liquid chamber lower plate 25 made of a plate material having high rigidity such as S is placed on the corresponding surfaces of the fluid resistance layer 26, and is pressed for 30 seconds.
Joining by heating at 0 ° C. Then, as shown in FIG. 3B, the liquid chamber upper plate 24 and the nozzle plate 28 are
Alternatively, the corresponding surfaces are joined with a polyimide adhesive to form the liquid chamber unit 2.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 is an enlarged explanatory view of a main part of a fluid resistance portion of the ink jet head. In this embodiment, after applying the adhesion improving agent 61 such as a silane coupling agent on the diaphragm 23 by, for example, spin coating,
The fluid resistance layer 26 is formed by laminating or coating a photosensitive resin in the same manner as in the above embodiments, and is joined to the liquid chamber lower plate 25.

Also, an adhesion improving agent 62 such as a positive resist is patterned on the surface of the liquid chamber lower plate 25 to be joined to the fluid resistance layer 26, and joined to the fluid resistance layer 26.

As described above, the adhesion improving agent 61 is attached to the vibration plate 23 and the liquid chamber lower plate 25 which are the two members sandwiching the fluid resistance layer 26.
By applying 62, the adhesive force (bonding force) with the fluid resistance layer 26 is improved, and the fluid resistance layer 6 made of a photosensitive resin is formed.
Can be prevented from peeling, and the reliability is improved.

In this case, a positive resist can be easily applied by using a positive resist when patterning is required, and by using a silane coupling agent in the case of applying the whole surface, as the adhesion improver. Further, it is preferable that the applied punishment thickness does not exceed 0.5 μm.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 is an enlarged explanatory view of a main part of a fluid resistance portion of the ink jet head. In this embodiment, an oxide film 63 is formed on the surface of the liquid chamber lower plate 25 that is joined to the fluid resistance layer 26. For example, SU
When an S plate is used, a thermal oxide film 63 can be formed by performing a heat treatment at about 300 ° C. for 1 hour in the air before joining to the fluid resistance layer 26.

As described above, by forming the oxide film 63 on the liquid chamber lower plate 25 which is a member sandwiching the fluid resistance layer 26,
The adhesion between the fluid resistance layer 26 made of a photosensitive resin and the liquid chamber lower plate 25 made of a metal plate can be improved, and the reliability is improved. Note that an oxide film may be formed on the surface of the diaphragm 23 by patterning or the like.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
0 will be described. FIG. 2 is an exploded view of the liquid chamber unit of the inkjet head. In this embodiment, the fluid resistance layer 26 is composed of a lower fluid resistance layer 26a made of a photosensitive resin and an upper fluid resistance layer 26b made of a photosensitive resin.
Are joined to form a two-layer structure.

In this case, a lower fluid resistance layer 26a made of a patterned photosensitive resin layer is formed on the vibration plate 23, while an upper fluid resistance layer 26 made of the patterned photosensitive resin layer is formed on the liquid chamber lower plate 25. After forming the layer 26b, the upper fluid resistance layers 26a and 26b are laminated at corresponding positions under these layers, and are joined by pressing and heating.

As described above, by forming the fluid resistance layer 26 into a multilayer structure, the adhesive strength of the fluid resistance layer 26 is improved, and the reliability is improved. That is, the adhesive strength between the laminated film-shaped photosensitive resin layer and the metal plate when the laminated film-shaped photosensitive resin layer and the metal plate are heated under pressure is twice or more.

Next, the layer thickness (film thickness) of the fluid resistance layer 26 and the degree of the film thickness unevenness (variation) will be described. For example, when forming the pressurized liquid chamber at a pitch of 150 dpi, the width of the fluid resistance is preferably 60 μm or less, and considering the etching resolution of the photosensitive resin film, the fluid resistance layer 2
Preferably, the thickness of 6 does not exceed 50 μm.

It is preferable that the variation in the thickness of the fluid resistance layer 26 does not exceed ± 5 μm. That is, a plurality of samples having different thicknesses and variations before joining the liquid chamber lower plate 25 to the fluid resistance layer 26 formed of the photosensitive resin layer patterned on the vibration plate 23 are manufactured and degassed. After the ink was permeated into the ink, it was dried, and the state of ink permeation into the bonding area was observed with a microscope. Table 1 shows the results.

[0043]

[Table 1]

As can be seen from Table 1, unless the film thickness unevenness (film thickness variation) before joining does not exceed ± 5 μm, the photosensitive resin layer is deformed by pressurizing and heating at the time of joining, so that the film unevenness is caused by unevenness. However, if the film thickness is more uneven, pressure unevenness at the time of bonding occurs, the adhesive strength is reduced, and the ink sealability is reduced. Accordingly, the ink sealing property can be ensured by making the thickness variation before joining less than ± 5 μm so that the thickness unevenness after joining does not exceed ± 5 μm.

In the above embodiment, the present invention has been described as an example in which the present invention is applied to a piezo type ink jet head using an electromechanical transducer as an actuator.
The present invention can be similarly applied to an ink jet head that ejects ink droplets by film boiling caused by a heating resistor.

[0046]

As described above, according to the ink jet head of the present invention, the fluid resistance portion for supplying ink to the liquid chamber to which the nozzle for discharging ink droplets communicates has the fluid resistance layer made of photosensitive resin. Since it is configured to be sandwiched between two members made of a material other than the photosensitive resin, deterioration in image quality due to ink swelling can be reduced, and high image quality can be stably secured over time.

Here, the fluid resistance layer can be easily formed by forming the fluid resistance layer from a film-shaped photosensitive resin or a liquid photosensitive resin. In addition, since one member sandwiching the fluid resistance layer is a diaphragm forming the wall surface of the liquid chamber, the configuration of the liquid chamber is simplified.

Further, by applying an adhesion improving agent to at least one of the members sandwiching the fluid resistance layer,
The joining force between the fluid resistance layer made of a photosensitive resin and the member sandwiching the fluid resistance layer is improved, and the reliability is improved. Furthermore, by forming an oxide film on the surface of at least one of the members sandwiching the fluid resistance layer, the joining force between the fluid resistance layer made of a photosensitive resin and the member sandwiching the fluid resistance layer is improved, and reliability is improved. improves.

Further, by forming the fluid resistance layer into a multi-layer structure, it is possible to easily form a complicated form of fluid resistance, and to join the fluid resistance layer made of a photosensitive resin with a member sandwiching the fluid resistance layer. And reliability is improved. In this case, the bonding strength can be improved by forming a photosensitive resin layer for forming the fluid resistance layer on each of the members sandwiching the fluid resistance layer and joining the photosensitive resin layers to each other.

By setting the thickness of the fluid resistance layer not to exceed 50 μm, the etching accuracy of the fluid resistance width required for a high-density head can be guaranteed, and the reliability is improved. Furthermore, by ensuring that the variation in the thickness of the fluid resistance layer does not exceed ± 5 μm, the ink sealability can be reliably ensured and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of an inkjet head according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the head in a direction between rows.

FIG. 3 is an enlarged sectional view of a main part of the head in a direction between channels.

FIG. 4 is an explanatory view illustrating a manufacturing process of a liquid chamber unit of the inkjet head.

FIG. 5 is an explanatory view illustrating a manufacturing process of the liquid chamber unit.

FIG. 6 is an explanatory plan view of the fluid resistance layer of FIG. 4 (e).

FIG. 7 is an explanatory view illustrating a manufacturing process of a liquid chamber unit according to a second embodiment of the present invention.

FIG. 8 is an explanatory view of a main part of a fluid resistance portion according to a third embodiment of the present invention.

FIG. 9 is an explanatory view of a main part of a fluid resistance portion according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory view of a main part of a liquid chamber portion according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drive unit, 2 ... Liquid chamber unit, 3 ... Nozzle cover, 4 ... Spacer member, 11 ... Substrate, 12 ... Piezoelectric element,
13: frame member, 23: diaphragm, 24: liquid chamber upper plate,
25: liquid chamber lower plate, 26: fluid resistance layer, 26a: lower fluid resistance layer, 26b: upper fluid resistance layer, 27: nozzle, 28: nozzle plate

Claims (9)

[Claims] 1. An ink jet head for supplying ink via a fluid resistance portion to a liquid chamber to which a nozzle for discharging ink droplets communicates, wherein the fluid resistance portion includes a fluid resistance layer made of a photosensitive resin other than the photosensitive resin. An ink jet head formed between two members made of a material. 2. The ink jet head according to claim 1, wherein the fluid resistance layer is formed of a film-shaped photosensitive resin or a liquid photosensitive resin. 3. The ink jet head according to claim 1, wherein one of the members sandwiching the fluid resistance layer is a diaphragm forming a wall surface of the liquid chamber. 4. The ink jet head according to claim 1, wherein an adhesion improving agent is applied to at least one of the members sandwiching the fluid resistance layer. 5. The ink-jet head according to claim 1, wherein an oxide film is formed on a surface of at least one of the members sandwiching the fluid resistance layer. 6. The ink jet head according to claim 1, wherein the fluid resistance layer has a multilayer structure. 7. The ink jet head according to claim 6, wherein a photosensitive resin layer forming a fluid resistance layer is formed on each of the members sandwiching the fluid resistance layer, and the photosensitive resin layers are joined to each other. An ink jet head characterized by the following. 8. The ink jet head according to claim 1, wherein the thickness of the fluid resistance layer is 5
An ink jet head characterized by not exceeding 0 μm. 9. The ink jet head according to claim 1, wherein a variation in the thickness of the fluid resistance layer does not exceed ± 5 μm.