JPH1034919A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the bonding reliability of an ink jet head having a diaphragm being deformed through a piezoelectric element by roughening the surface of the diaphragm to be bonded with other member. SOLUTION: When an actuator unit 1 is bonded to a liquid chamber unit 2, the actuator is coated at first with an adhesive by screen printing and set on a bonder and then the bonder is set in a liquid chamber unit 2. Subsequently, both units 1, 2 are aligned and bonded temporarily through adhesive. It is then taken out from the bonder and set in a pressurization unit and thermally set in a thermostatic bath while being pressurized, thus completing the bonding. In this regard, the bonding face of the liquid chamber unit 2, i.e., the bonding face of a diaphragm 12, is roughened in order to enhance bonding force with the adhesive. The roughening process includes chemical processing, e.g. immersion into aqueous solution of iron chloride or hydrochloric acid, electrical processing, e.g. corona discharge, and physical processing, e.g. dry etching.

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 a diaphragm of an ink jet head.

[0002]

2. Description of the Related Art An ink jet recording apparatus has almost no vibration and noise during recording, and is particularly easy to colorize.
In addition to a printer that outputs data from a digital processing device such as a computer, it is also used for facsimile machines, copiers, and the like. An ink jet head used in such an ink jet recording apparatus records an image on a recording medium by ejecting ink droplets from nozzles by driving actuator elements such as a piezoelectric element and a heating resistor in accordance with a recording signal. It is what you do.

[0003] Ink jet heads are structurally classified roughly into an edge shooter type in which ink droplets are ejected from the end face side of the stack of head constituent members and a side shooter type in which a circular nozzle is formed in a nozzle forming member. can do. Conventionally, as a side shooter type inkjet head, as described in, for example, JP-A-6-255099, a diaphragm having a diaphragm portion is laminated on a piezoelectric element, and a piezoelectric element is formed on the diaphragm. A nozzle chamber formed by laminating a liquid chamber pressurized via a diaphragm portion and a flow path forming member forming an ink supply path for supplying ink to the liquid chamber, and further forming a nozzle on the flow path forming member Are known.

[0004]

By the way, in accordance with the demand for high speed and high image quality of the ink jet recording apparatus, the ink jet head is arranged with a large number of nozzles at a high density. The liquid chambers which communicate with each other, the ink supply path for supplying ink to the liquid chambers, the diaphragm of the diaphragm, the piezoelectric elements for pressing each liquid chamber, and the like are also arranged in high density.

Therefore, individual components such as a piezoelectric element, a diaphragm, a flow path forming member, a nozzle forming member, etc. are formed with high precision and assembled with high precision, and peeling of the respective components at the joint surface is prevented. It is indispensable to improve the bonding reliability so as not to occur.

The present invention has been made in view of the above points, and has as its object to improve the bonding reliability of an ink jet head.

[0007]

According to a first aspect of the present invention, there is provided an ink-jet head having a diaphragm deformed by a piezoelectric element, wherein the diaphragm is joined to another member. Was subjected to a surface treatment for roughening.

According to a second aspect of the present invention, in the inkjet head of the first aspect, the actuator unit having the piezoelectric element and the liquid chamber unit having the diaphragm are joined.

According to a third aspect of the present invention, in the inkjet head of the first or second aspect, the joining surface of the vibration plate is the piezoelectric element.

A fourth aspect of the present invention is the ink jet head according to any one of the first to third aspects, wherein the surface treatment is performed by a chemical treatment.

According to a fifth aspect of the present invention, in the ink jet head according to any one of the first to third aspects, the surface treatment is performed by an electrochemical treatment.

According to a sixth aspect of the present invention, in the ink jet head of any one of the first to third aspects, the surface treatment is performed by an electrical treatment.

According to a seventh aspect of the present invention, in the ink jet head according to any one of the first to sixth aspects, the bonding surface of the diaphragm has a surface roughness R after surface treatment.
ma × 0.2 or more.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an external perspective view showing an example of an inkjet head to which the present invention is applied, FIG. 2 is an exploded perspective view of the inkjet head, and FIG.
FIG. 4 is an enlarged sectional view of a main part along a line BB in FIG. 1.

The ink jet head comprises an actuator unit 1 and a liquid chamber unit 2 joined on the actuator unit 1. The actuator unit 1 joins two laminated piezoelectric elements 4 and 4 on an insulating substrate 3 and a frame 5 made of an insulating material surrounding the two rows of piezoelectric elements 4 and 4 with an adhesive 6. ing. The piezoelectric element 4 includes a plurality of actuators 7 to which drive pulses for applying ink to droplets and flying ink droplets are provided.
A plurality of non-driving portions 8, 8... Serving as support portions to which a driving pulse is not applied are alternately arranged.

The liquid chamber unit 2 includes a first photosensitive resin layer 13 serving as a flow path forming portion formed of a photosensitive resin film (dry film resist) on a diaphragm 12 having a diaphragm portion 11, and a second photosensitive resin. A layer 14, a third photosensitive resin layer 15, and a nozzle plate 17, which is a nozzle forming member having nozzle holes 16, are sequentially laminated to form a plurality of pressurized liquid chambers serving as ink flow paths corresponding to the respective driving units 7. 18, 18 ...,
A plurality of common liquid chambers (common ink flow paths) 19, 19 for supplying ink to the pressurized liquid chambers 18, 18, and an ink flow path forming an ink supply path connecting the common liquid chamber 19 and the pressurized liquid chamber 18 Are formed respectively as ink supply paths 20, which also serve as fluid resistance portions. The liquid chamber unit 2 is firmly bonded to the actuator unit 1 with a bonding agent 21.

The substrate 3 of the actuator unit 1 has a thickness of about 0.5 to 5 mm and is made of a material similar to a piezoelectric element, and can be cut together with the piezoelectric element by, for example, a diamond grindstone. Preferably,
In this embodiment, a ceramic substrate is used. Also,
A groove 25 is formed between the piezoelectric elements 4 and 4 of the substrate 3 along the direction in which the drive units 7 are arranged.

The piezoelectric element 4 is a laminated piezoelectric element as shown in FIGS. 3 and 4, and has a thickness of 20 to 50 μm / 1 layer of PZT (= Pb (Zr · Ti) O ₃ ) 27 and Several μm /
Internal electrode 2 consisting of one layer of silver / paradium (AgPd)
8 are alternately laminated. Piezoelectric element with thickness 2
The drive voltage can be reduced by using a stacked type of 0 to 50 μm / 1 layer, and for example, an electric field strength of 1000 V / mm of the piezoelectric element can be obtained with a pulse voltage of 20 to 50 V. The material used for the piezoelectric element is not limited to the above.

Each internal electrode 28 of the piezoelectric element 4 is connected to left and right external electrodes 30 and 31 made of AgPd every other layer. On the other hand, a common electrode pattern 32 for applying a driving waveform to the driving unit 7 is formed on the substrate 3 between the laminated piezoelectric elements 4 and 4, and a selection signal is supplied to the driving unit 7. Are provided.

Then, the external electrode 30 of each drive unit 7 is connected to the common electrode pattern 32 via a conductive adhesive 34 such as a silver paste, and the external electrode 31 is similarly connected to the conductive adhesive 34.
Is connected to the individual electrode pattern 33 via the. In addition,
The common electrode pattern 32 is formed on the surface of the groove 25 formed in the center of the substrate 3 so as to conduct with the respective driving units 7. Then, an FPC cable 35 is connected to each of the common electrode pattern 32 and the individual electrode pattern 33.

On the other hand, the vibrating plate 12 of the liquid chamber unit 2 has independent island-shaped convex portions 12a corresponding to the driving portions 7 of the piezoelectric elements 4.
The diaphragm portion 11 which is located around the island-shaped convex portion 12a and is deformed by the displacement of the driving portion 7 of the piezoelectric element 4;
Thick rigid body 1 located around this diaphragm 11
2b is formed. The diaphragm portion 11 is a thinnest region (thin portion) and has a thickness of 3 to 10 μm.
About. In addition, the island-shaped convex portion 12a is a region having a large thickness, a joint region with the driving unit 7, and a thick rigid portion in the channel direction (the direction shown in FIG. 4).
The thick rigid body portion 12b is an area for joining the liquid chamber unit 2 to the frame 5. Here, the surfaces of the island-shaped convex portion 12a and the thick rigid body portion 12b serve as bonding surfaces for bonding to the piezoelectric element 4 and the frame 5, which are other members.

The material forming the vibration plate 12 can form an elastic portion capable of transmitting the pressing force of the driving unit 7 to the pressurized liquid chamber 18, has good liquid resistance to ink, and has low moisture permeability. Good. However, the diaphragm 12 has a Young's modulus of 100 in order to join the non-drive unit 8 with high rigidity.
It is preferable to use an inelastic material of Kg / mm ² or more. Here, a Ni (nickel) metal plate manufactured by the electron forming method (electroforming) as described above is used.
A very thin resin film having low moisture permeability, for example, a resin film of polyphenylene sulfide, polyimide, polyether sulfone, polychlorotrifluoroethylene, aramid, or the like can also be used.

A large number of nozzles 16 are formed in the nozzle plate 17 as fine holes for ejecting ink droplets. The diameter of the nozzles 16 is 35 μm or less on the ink droplet outlet side. I have. This nozzle plate 1
Reference numeral 7 uses a Ni (nickel) metal plate manufactured by an electron forming method (electroforming), but Si or another metal material can also be used. In practice, 32 to 64 or more nozzles 16 are arranged in two rows.
One inkjet head is manufactured with a configuration of 64 to 128 or more arranged in rows. The quality of the nozzle plate 17 having a large number of nozzles 16 determines the shape of ink droplets and the flight characteristics, and greatly affects image quality. In order to obtain higher quality image quality, it is essential to perform a uniform surface treatment.
Is formed.

Further, the substrate 3, the frame 5, and the diaphragm 1
2, ink supply holes 37, 38, and 39 for supplying ink supplied from the outside to the common liquid chamber 19 are respectively formed, and the ink supply pipes 40 connected to the ink supply holes 37 of the substrate 3 are provided. Ink is supplied.

Next, the manufacturing process of the ink jet head will be described. This ink jet head is manufactured by separately assembling the actuator unit 1 and the liquid chamber unit 2 in advance, and then bonding and bonding the units 1 and 2 to each other. By adopting such a manufacturing process,
A non-defective product of the two units 1 and 2 can be selected and assembled, thereby improving the yield, and also having an actuator unit 1 in which dust is likely to be generated in the processing and assembling process, and a liquid chamber unit 2 in which dust should be completely prevented from adhering. Can be assembled in separate steps, so that the quality itself of the completed inkjet head is improved. Hereinafter, a specific description will be given.

First, the steps of processing and assembling the actuator unit 1 are as follows. That is, the Ni / Au vapor deposition electrode pattern for the individual electrode and the Ni / Au vapor deposition electrode pattern for the common electrode are roughly patterned on the insulating substrate 3 in advance, and a plate-shaped laminated piezoelectric element is used using a positioning jig. Then, the end face electrodes formed on both end faces of each laminated piezoelectric element and the electrode patterns for the individual electrodes and the common electrodes of the substrate 3 are electrically connected with a conductive adhesive.

After that, the laminated piezoelectric element is slit into, for example, a width of about 100 μm per pitch by a dicer or the like on which a diamond grindstone is set, and divided into individual piezoelectric elements to be the driving unit 7 and the non-driving unit 8. Then
The frame 5 is adhesively bonded on the substrate 3. Then, FPC
The cable 35 is joined to the electrode pattern of the substrate 3 by heat and pressure. The FPC cable 35 has a pattern capable of selectively driving the piezoelectric element serving as the drive unit 7, and its joint is plated in advance with solder. Finally, the capacitance of each piezoelectric element is measured.

On the other hand, the processing and assembling process of the liquid chamber unit 2 will be described. The diaphragm 12 having the diaphragm portion 11 made of a Ni (nickel) metal plate and the nozzle 16 by using an electron forming method (electroforming) in advance. Is manufactured.

Then, using a photosensitive resin film (dry film resist) on the vibration plate 12 and using a mask corresponding to the flow path pattern, ultraviolet exposure is performed to cure the exposed portion and remove the unexposed portion. A necessary flow path pattern is formed by removing and developing an unexposed portion using a solvent that can be formed, washed with water, dried, and then completely cured by ultraviolet exposure and heat to form the first photosensitive resin layer 13. Form. On the other hand, a third photosensitive resin layer 15 and a second photosensitive resin layer 14 for forming a required liquid chamber pattern on the nozzle plate 17 using the same photosensitive resin film (dry film resist).
Are sequentially formed.

Then, the first photosensitive resin layer 13 and the second photosensitive resin layer 14 made of the dry film resist thus formed on the vibration plate 12 and the nozzle plate 16 are joined. This joining is performed using a positioning jig,
Pressurization and heating at a higher temperature than during the main curing are performed. Actually, in the above steps, assembling is performed using a plate having a head area corresponding to a plurality of heads.

Finally, the actuator unit 1 and the liquid chamber unit 2 completed as described above are assembled.
In this joining, an adhesive is applied to the actuator 1 by screen printing and set in a joining device, and then the liquid chamber unit 2 is set in the joining device. Then, the relative positions (X, Y directions) of the actuator 1 and the liquid chamber unit 2 are aligned at the micron order level by the joining device, and the two units are brought into contact and joined while maintaining the positional relationship. Next, ultraviolet curing (U
V) Temporary joining is performed with an adhesive, and after completion, the joined object is taken out of the joining device and set in a pressing device. After that, it is put into a constant-temperature layer together with the pressurizing device in a pressurized state and thermally cured to complete.

A description will now be given of the inter-unit bonding in such an ink-jet head and the roughening treatment of the diaphragm 12 constituting the liquid chamber unit 2. The adhesive used for bonding between the actuator unit 1 and the liquid chamber unit 2 is, for example, 9752L-ZnO.
(Trade name, manufactured by Nippon Able Stick Co., Ltd.). The material to be adhered during unit-to-unit bonding is a vibration plate 12 (for example, Ni metal) that is a liquid chamber unit bonding surface and a piezoelectric element 4 that is an actuator unit bonding surface.
(For example, PZT) and a frame 5 (for example, a thermosetting resin).

Here, if the bonding tensile strength of the adhesive used for unit-to-unit bonding is low, for example, a defect such as separation occurs at the adhesive interface between the piezoelectric element serving as the driving unit and the vibration plate, and a non-ejection nozzle is generated. And the image quality is degraded. For example, the above-mentioned adhesive 9752L-ZnO has a low bonding tensile strength with electroformed Ni metal, and is about 7 kgf / cm ² according to experiments, and a defect such as peeling occurs at such a bonding strength. Therefore, when an evaluation test was performed, a tensile strength of 10
It was confirmed that peeling occurred at less than kgf / cm ² .

Therefore, in the present invention, the bonding strength with the adhesive is improved by performing a surface treatment for roughening the bonding surface of the diaphragm which is the bonding surface of the liquid chamber unit. here,
Examples of the surface roughening treatment of the diaphragm include chemical treatment such as immersion in an aqueous solution of iron chloride, hydrochloric acid, and chromic acid, electrochemical treatment such as forming a chromic acid film, and electric treatment such as corona discharge. Physical processing such as dry etching, and mechanical processing such as sandblasting.

A specific example of this surface treatment will be described.
Here, the surface of the diaphragm component was immersed in an aqueous solution of iron chloride to increase the surface roughness. An example of the immersion condition of the aqueous solution of iron chloride on the joint surface of the Ni diaphragm is as follows. Treatment sample: Ni diaphragm Aqueous solution concentration: 5 to 50% wt iron chloride aqueous solution Aqueous solution temperature: 22 to 50 ° C Immersion time: 3 to 20 seconds

When the surface treatment was performed under the above conditions, the surface roughness (surface roughness) of the joint surface of the diaphragm was calculated as Rma ×
By using 0.2 or more, the used adhesive 9752L
-The tensile strength between ZnO and electroformed Ni diaphragm is 50kgf
/ Cm ² or more, and peeling was prevented.

Next, a manufacturing process of a diaphragm having such an iron chloride aqueous solution immersion process will be described with reference to FIGS. First, as shown in FIG. 5A, a conductor film 52 is formed on a cleaned glass substrate 51 as an electroformed support substrate by Ni sputtering with a thickness of about 800 Å as shown in FIG. 5B. Then, a portion where no diaphragm is formed is masked by a photolithography process (not shown). In the drawings, only a part of the portion forming the diaphragm is shown.

Thereafter, as shown in FIG. 2C, a first Ni layer 53 for forming the diaphragm portion 11 is formed on the conductor film 52 by Ni electroforming. Next, as shown in FIG. 3D, a predetermined resist pattern 54 is formed on the first Ni layer 53 by a photolithography process, and the surface of the first Ni layer 53 is activated. 1st as shown
A second Ni layer 55 for forming the thick rigid portion 12b and the island-shaped convex portion 12a is formed on the Ni layer 53 by Ni electroforming.

Further, as shown in FIG. 6A, a predetermined resist pattern 56 is formed on the resist pattern 54 by a photolithography process, and the surface of the second Ni layer 55 is activated. As shown in FIG. 5, a third Ni layer 57 for forming the thick rigid portion 12b and the island-shaped convex portion 12a is formed on the second Ni layer 55 by Ni electroforming. Then, as shown in FIG. 3C, an immersion treatment with an aqueous solution of iron chloride is performed, and the third Ni layer 5 is formed.
A roughened surface 58 is formed on the seven surfaces. Next, as shown in FIG. 4D, the resist patterns 54 and 56 are peeled off and separated from the glass substrate 51 to obtain the diaphragm 12 having a roughened bonding surface.

That is, after the diaphragm portion 11 of the diaphragm 12 is covered with the resist pattern 61 (the above-described resist patterns 54 and 56) as shown in FIG. The resist pattern 61 is removed as shown in FIG. By performing the surface treatment for roughening only in a specific range as described above, for example, the diaphragm portion 11 is protected by a resist pattern mask in an immersion treatment with an iron chloride aqueous solution. It is possible to prevent pinholes and the like from being generated by erosion with the aqueous solution.

In the above embodiment, the liquid chamber unit having the vibration plate and the actuator unit having the piezoelectric element are separately manufactured in advance, and the ink jet head is assembled by joining the two units. The present invention can be similarly applied to an inkjet head having a structure in which a vibration plate is joined to a piezoelectric element and a flow path forming member is joined and assembled on the vibration plate. Further, the present invention can be applied not only to an inkjet head having a side shooter structure but also to an inkjet head having an edge shooter structure. Further, as described above, the diaphragm may be other than the electroformed one.

[0042]

As described above, according to the ink-jet head of the first aspect, in the ink-jet head having the vibrating plate deformed by the piezoelectric element, the surface of the vibrating plate joined to another member is roughened. Since the surface treatment is applied, the reliability of joining the diaphragm to another member can be improved.

According to the ink jet head of the second aspect, in the ink jet head of the first aspect, the actuator unit having the piezoelectric element and the liquid chamber unit having the vibration plate are joined to each other. Reliability can be improved.

According to the ink jet head of the third aspect, in the ink jet head of the first or second aspect, since the joining surface of the vibration plate is a piezoelectric element,
The joining reliability between the diaphragm and the piezoelectric element can be improved. .

According to the ink jet head of the fourth aspect, in the ink jet head of any one of the first to third aspects, the surface treatment is performed by a chemical treatment. Performance can be improved.

According to the ink jet head of the fifth aspect, in the ink jet head according to any one of the first to third aspects, the surface treatment is performed by an electrochemical treatment, so that the vibration plate and other members can be connected to each other. Joint reliability can be improved.

According to the ink jet head of the sixth aspect, in the ink jet head of any one of the first to third aspects, the surface treatment is performed by an electric treatment, so that the vibration plate is joined to another member. Reliability can be improved.

According to the ink jet head of claim 7, in the ink jet head of any one of claims 1 to 6, the bonding surface of the diaphragm has a surface roughness after surface treatment of Rma × 0.2 or more. So that the joining tensile strength can be 10 kgf / cm ² or more,
The joining reliability between the diaphragm and other members can be improved.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an example of an inkjet head to which the present invention is applied.

FIG. 2 is an exploded perspective view of the inkjet head.

FIG. 3 is an enlarged sectional view of a main part along the line AA in FIG. 1;

FIG. 4 is an enlarged sectional view of a main part along the line BB in FIG. 1;

FIG. 5 is a process explanatory view for explaining a manufacturing process of the diaphragm.

FIG. 6 is a process explanatory view for explaining a manufacturing process of the diaphragm.

FIGS. 7A and 7B are explanatory views for explaining surface treatment of a diaphragm, wherein FIG. 7A is a schematic side view, and FIG.

8A and 8B are explanatory diagrams for explaining surface treatment of a diaphragm, wherein FIG. 8A is a schematic side view, and FIG.

[Explanation of symbols]

1. Actuator unit, 2. Liquid chamber unit, 3.
Frame, 4: piezoelectric element, 7: drive unit, 8: non-drive unit,
DESCRIPTION OF SYMBOLS 11 ... diaphragm part, 12 ... diaphragm, 12a ... island-shaped convex part, 12b ... thick rigid body part, 13, 14, 15 ... photosensitive resin layer, 16 ... nozzle, 17 ... nozzle plate, 18 ... pressurized liquid chamber , 19 ... common liquid chamber, 20 ... ink supply path, 58 ...
Roughened joint surface.

Continued on the front page (72) Inventor Masayuki Iwase 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hideyuki Makita 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yoichiro Miyaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kunio Ikeda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company

Claims (7)

[Claims] 1. An ink jet head having a diaphragm deformed by a piezoelectric element, wherein the surface treatment is performed to roughen a joint surface of the diaphragm with another member. 2. The ink jet head according to claim 1, wherein the head is formed by joining an actuator unit having the piezoelectric element and a liquid chamber unit having the diaphragm. 3. The ink-jet head according to claim 1, wherein a bonding surface of the vibration plate is the piezoelectric element. 4. The ink jet head according to claim 1, wherein said surface treatment is performed by a chemical treatment. 5. The ink-jet head according to claim 1, wherein said surface treatment is performed by an electrochemical treatment. 6. The ink jet head according to claim 1, wherein said surface treatment is performed by an electric treatment. 7. The ink jet head according to claim 1, wherein a surface roughness of the joint surface of the vibration plate after surface treatment is Rma × 0.2 or more. .