JP3480481B2 - Ink jet recording head and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for recording an image or a character on a recording sheet by ejecting ink droplets from a nozzle opening by expanding and contracting a piezoelectric vibrator in a longitudinal vibration mode, and more particularly, a piezoelectric vibration. The present invention relates to a mounting structure for a child and a frame.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening and a reservoir is formed by an elastic plate, and the elastic plate is elastically deformed by a piezoelectric vibrator that expands and contracts in the axial direction to expand the pressure generating chamber. The ink-jet recording head that contracts has a feature that it can be downsized and can be driven at high speed, as compared with a recording head that uses flexural vibration that deforms in the surface direction.

FIG. 9 shows an example of an ink jet recording head using such a longitudinal vibration mode piezoelectric vibrator. In the figure, reference numeral 40 is a longitudinal vibration mode piezoelectric vibrator, and a conductive layer 41, 42 and piezoelectric material layers 43 are alternately laminated, and the inactive region formed at the rear end is fixed to a fixed substrate 44 to be assembled into a vibrator unit, and the tip end of each piezoelectric vibrator 40 is fixed. The fixed substrate 44 is directly fixed to the frame 45 by the adhesive agent P so that the fixed substrate 44 is positioned so that the thick plate portion 40 a of the elastic plate 47 that seals the pressure generating chamber 46 contacts.

The elastic plate 47, the flow path forming plate 51, and the nozzle plate 52 are laminated and fixed on the surface 50 of the frame 45 to be assembled into an ink jet recording head. Reference numeral 53 in the figure indicates a thin portion formed on the peripheral edge of the thick portion 48.

[0005]

However, the distortion due to the difference in the coefficient of thermal expansion between the ceramics forming the piezoelectric vibrator 40 and the material forming the frame 45, such as plastic, is almost the same as the length of the piezoelectric vibrator 40. It occurs in proportion to L. Due to this, for example, when heating is performed in the bonding step in order to obtain stronger bonding strength, a temperature difference of 40 ° C. occurs when the temperature is returned to room temperature, and the free end length L of the piezoelectric vibrator 40 is 5 In the case of 0.5 mm, there is a problem that the expansion difference of about 10 μm occurs and the elastic plate 47 is damaged. In order to solve such a problem, it may be considered that the frame 45 is made of the same ceramic as that of the piezoelectric vibrator 40, but it takes time to process the ceramic, which is a hard material, so that the cost is increased. There's a problem.

Furthermore, in order to meet the demand for high-density printing, a recording head in which a large number of nozzle openings are arranged in one row has been put into practical use. In such a multi-nozzle recording head, a piezoelectric vibrator unit configured by fixing a large number of piezoelectric vibrators in a longitudinal vibration mode to a fixed substrate at a fixed pitch is used as a drive source. For this reason, the reaction force of the piezoelectric vibrator unit at the time of ink droplet ejection becomes large, and the adhesive layer P fixing the fixed substrate 44 fixing the piezoelectric vibrator 40 and the frame 45 is easily elastically deformed. , Piezoelectric vibrator 4
The pressing force of the pressure generating chambers 46 due to 0 decreases, and the pressing forces of the piezoelectric vibrators 40 arranged in a large number in the same row cause a difference between the ones located in the central portion and those located in the end portions. There is a problem that print quality is degraded.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the difference in thermal expansion between the piezoelectric vibrator and the frame regardless of changes in temperature. Moreover, it is an object of the present invention to provide an ink jet recording head capable of increasing the rigidity of the bonding area between the piezoelectric vibrator and the frame. Another object of the present invention is to
It is to propose a method for manufacturing the recording head.

[0008]

In order to solve such a problem, in the present invention, piezoelectric materials and conductive layers are alternately laminated, and a plurality of piezoelectric vibrators operating in a longitudinal vibration mode and a nozzle opening are provided. A flow path unit including a perforated nozzle plate, a flow path forming plate that forms a pressure generating chamber and a reservoir, and an elastic plate with which the tip of the piezoelectric vibrator contacts, the piezoelectric vibrator, and the flow path unit. In the ink jet recording head including a frame for fixing the piezoelectric vibrator, the plurality of piezoelectric vibrators are provided on a fixed substrate extending from a rear end of the piezoelectric vibrator to a front end region, and a rear end region of the piezoelectric vibrator and the fixed substrate. A rear end region of the frame is fixed via a rear end plate, and the frame has an opening for inserting the piezoelectric vibrator together with the fixed substrate at one end, and a wall facing a rear surface of the fixed substrate. And an adhesive injection groove formed so as to extend from the wall surface to the overhang portion in the vicinity of the opening and an overhang portion facing the front end surface of the fixed substrate. The fixed substrate is fixed to the frame by an agent , and the remaining portions of the plurality of piezoelectric vibrators other than those fixed to the rear end plate are free ends , and the tip side of the fixed substrate.
The tip portion of the free end is in contact with the flow path unit.

[0009]

[Function] As the difference in thermal expansion caused by the difference in the material of the frame and the piezoelectric vibrator, only the portion corresponding to the thickness of the overhang portion of the frame is involved, which is high in order to accelerate the solidification of the adhesive. Even if heat of temperature is applied, the difference in thermal expansion between the frame and the piezoelectric vibrator can be suppressed to an extremely small value, and the capillary force of the groove surely causes the adhesive to enter between the overhang portion and the fixed substrate to cause the overhang. The part and the fixed substrate are securely bonded and fixed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to illustrated embodiments. FIG. 1 is a perspective view showing an embodiment of the ink jet recording head of the present invention,
FIG. 2 is a diagram showing a cross-sectional structure in the vicinity of one piezoelectric vibrator, in which reference numeral 1 is a nozzle plate, for example, 18
Nozzle openings 2.2 with a predetermined pitch of about 0 DPI,
2 ... has been drilled.

Reference numeral 3 denotes a flow path forming plate, which is composed of a pressure generating chamber 5 so as to communicate with the nozzle opening 2, a reservoir 6 for supplying ink to these pressure generating chambers 5, and a reservoir 6 and each pressure generating chamber. The ink supply port 7 to be connected is formed.

Reference numeral 4 denotes an elastic plate, which is fixed to the back surface side of the flow path forming plate 3, that is, the surface facing the nozzle plate 1 with the flow path forming substrate 3 interposed therebetween to form the pressure generating chamber 5 and the reservoir 6. , A thick portion 9 extending in the longitudinal direction of the pressure generating chamber 5 at a position corresponding to the center line of the pressure generating chamber 5, and a thick portion 9
An elastically deformable thin-walled portion 10 is formed around the circumference of the.

The thick portion 9 is in contact with the tip of a piezoelectric vibrator 8 formed by alternately laminating conductive layers 8-1 and 8-2 and a piezoelectric material 8-3. The rigidity is such that the axial displacement of 1 to 2 μm can be transmitted to the widest possible area of the thin portion 10 covering the pressure generating chamber 5.

With this structure, the pressure generating chamber 5 is efficiently contracted and expanded by the expansion and contraction of the piezoelectric vibrators 8 ...
The ink in the reservoir 6 can be sucked from the ink supply port 7 when contracting, and the ink in the pressure generating chamber 5 can be pressurized and ejected as an ink droplet from the nozzle opening 2 when expanding.

Reference numeral 20 in the drawing denotes a frame, which is shown in FIGS.
As shown in FIG. 5, it is configured as a cylindrical body provided with a housing chamber 25 capable of housing a piezoelectric vibrator unit 16 described later by injection molding of a polymer material or the like. An opening 11 for inserting the transducer unit 16 is provided at one end of the frame 20, and a flow path formed by integrally laminating the elastic plate 4, the flow path forming plate 3, and the nozzle plate 1 at the other end. A fixing portion 22 for fixing the unit 17 is formed.

The surface of the fixed portion 22 is fixed to the fixed portion 22.
A window 23 for exposing the tip of the piezoelectric vibrator 8 is formed so as to be flush with. An overhang portion 24 is integrally formed on the piezoelectric vibrator 8 side of the window 23 so as to project to the pressure generating chamber 5 and project to the vicinity of the thick portion 9 of the elastic plate 4.

Reference numeral 26 denotes a groove for injecting an adhesive, which is the fixed substrate 14.
A wall surface 27 facing the opening 11 extending linearly in the direction of the window 23 from the vicinity of the opening 11 and reaching the vicinity of the pressure generating chamber 5 side of the overhang portion 24 is formed in an "L" shape, and the center line c is arranged in the arrangement direction. Are formed so as to be symmetrical.
The upper end of the groove 26 has a widening portion 26 for guiding the insertion of the injection needle.
a is formed.

The groove 26 is formed to have a depth, for example, about 0.2 mm, so that the adhesive can be poured into a region where the overhang portion 24 and the tip 14a of the fixed substrate 14 face each other by a capillary force. In addition, the wall surface 27 of the frame 20
Is formed as an inclined surface so as to form a wedge-shaped gap 28 which is slightly wider on the side of the opening 11 with the fixed substrate 14 inserted vertically.

Next, the vibrator unit 16 will be described. The piezoelectric vibrator 8 for ejecting ink droplets is shown in FIG.
As shown in, it is configured by cutting a piezoelectric plate formed by laminating a piezoelectric material and an electrode material at a constant pitch,
At the time of this cutting, a dummy vibrator 18 is formed by leaving a member slightly thicker than the piezoelectric vibrator 8 on both sides.

The piezoelectric vibrator 8 and the dummy vibrator 18
The rear end plate 13 is fixed to the rear end plate 13 so as to have a constant pitch, and then the rear end plate 13 is fixed to the fixed substrate 14 to form the vibrator unit 16. The fixed substrate 14 includes a piezoelectric vibrator 8 so that its tip does not protrude from the overhang portion 24 toward the piezoelectric vibrator 8.
Slope 14b is formed on the tip side.

By thus forming the dummy vibrators 18, 18 on both ends of the vibrator unit 16, when the vibrator unit 16 is inserted into the frame 20, it is formed near the window 23 of the frame 20. The tip 8a of the piezoelectric vibrator 8 can be accurately brought into contact with the thick portion 9 of the elastic plate 4 because it functions as a guide member by coming into contact with the side wall 29 that is formed.

The fixed substrate 14 is preferably made of a material having a thermal expansion coefficient similar to that of the piezoelectric vibrator 8, for example, a piezoelectric material or another ceramic material. When it is necessary to secure rigidity in order to prevent crosstalk due to time stress, it is preferable to use a metal material.

Reference numeral 12 in the drawing denotes a cap which also serves as a shield plate, and 31 denotes a wall which divides the frame 20 into two housing chambers 25.

When the recording head is constructed by using the frame 20 constructed as described above, the frame 20 is set so that the fixing portion 22 thereof faces upward, and the fixing portion 2 is fixed.
The flow path unit 17 is fixed to the 2 through the adhesive layer.

Then, the frame 20 is set again so that the opening 11 is on the upper side, and then an adhesive is applied to the tip 8a of the vibrator 8 and the vibrator unit 16 is inserted from the opening 11, so that both sides of the fixed substrate 14 are fixed. The sides are guided by the guide portions 30 on both sides of the opening 11 of the frame 20, and the above-mentioned dummy vibrators 18, 18 are provided on the side wall 2 of the opening 11 of the frame 20.
It is guided by 9 and descends.

When the tip 8a of the piezoelectric vibrator 8 comes into contact with the thick portion 9 of the elastic plate 4, the position of the piezoelectric vibrator 8 in the axial direction is determined, and at this stage, it is fixed between the fixed substrate 14 and the wall surface 27. Of the fixed substrate 14 and a surface 24a of the overhang portion 24, a slight constant gap Δg is generated.

In this state, the groove 2 formed on the wall surface 27
When a predetermined amount of liquid adhesive is injected from the expanded portion 26a of No. 6 using an injection needle or the like, it travels through the groove 26 and the overhang portion 24
It flows into groove 26b formed on the surface 24a of spread throughout the gap Δg formed between the overhang portion 24 and the tip 14 a of the fixed substrate 14 by capillary force from here.

When the adhesive is further injected, the fixed substrate 1
The adhesive enters the narrow gap 28 formed by the groove 4 and the groove 26, penetrates into the gap between the fixed substrate 14 and the wall surface 27 of the frame 20 by the capillary force, and spreads throughout.

The adhesive that has penetrated into the gap Δg forms a meniscus by the surface tension at the end of the gap Δg between the overhang portion 24 and the fixed substrate 14 and stops. Therefore, even if a slightly larger amount of adhesive is injected, the excess adhesive does not flow out to the elastic plate 4 side.

In this state, it is heated to a temperature suitable for promoting the solidification of the adhesive, for example, 60 ° C. During the curing process, the frame 20 and the fixed substrate 14 expand based on the coefficients of thermal expansion of the materials forming them, but the thermal expansion coefficients of the piezoelectric vibrator 8 and the fixed substrate 14 are selected to be substantially the same. In addition, since the thickness L0 of the overhang portion 24 is about 1 mm, the free end length L of the piezoelectric vibrator 8 is even 5.5.
Even if it is as long as about mm, the difference in thermal expansion per temperature of 40 ° C is 1
To 2 μm, which is extremely small.

On the other hand, in the conventional ink jet recording head (FIG. 9), since the other end side of the piezoelectric vibrator 40 is fixed to the frame, the free end length L of the piezoelectric vibrator L = 5.5 mm. Due to the thermal expansion strain of the frame 45 having the same length as the above, the difference due to the difference in thermal expansion is about 5 to 10 μm, which is about 5 times larger than that of the present invention.

Since the entire surface of the fixed substrate 14 having a length substantially equal to that of the piezoelectric vibrator 8 is fixed to the frame 20, the strength of the adhesive layer P interposed between the fixed substrate 14 and the frame 20. Therefore, the reaction force of the piezoelectric vibrator 8 can be received by the entire frame.

In the above-described embodiment, the groove 26 for injecting the adhesive is extended to the piezoelectric vibrator 8 side of the overhang portion 24. However, as shown in FIG.
Is formed so as to be a dead end on the same surface as the surface 24a of the overhang portion 24, the adhesive is formed by the narrow and upwardly expanding wedge-shaped gap 28 and groove 26 formed by the fixed substrate 14 and the wall surface 27. Flows into the same surface as the surface 24a of the overhang portion 24 by the capillary force.

Next, the adhesive is applied to the tip 14 of the fixed substrate 14.
a and the surface 24a of the overhang portion 24 flow into the gap Δg by a capillary force, and the gap Δg between the tip 14a of the fixed substrate 14 and the surface 24a of the overhang portion 24.
It diffuses throughout and is cured by the entire surface where the tip 14a of the fixed substrate 14 and the overhang portion 24 face each other to fix them.

Groove 26b extends to the surface of overhang portion 24
In the above-described embodiment in which the overhang portion 2 is formed,
When the groove 26b on the surface 24a of No. 4 can be formed with high accuracy, the tip 14a of the fixed substrate 14 and the overhang portion 24 are formed.
Although the adhesive can be positively evenly diffused and surely adhered to the surface 24a of the overhanging portion 24a by the groove 26b, it is difficult to form the groove 26b on the surface 24a of the overhang portion 24 with high accuracy. Easy to accompany.

On the other hand, the tip 14a of the fixed substrate 14,
Also, since it is relatively easy to ensure the flatness of the surface 24a of the overhang portion 24, the groove 26b of the overhang portion 24, which may occur due to the defect of the groove 26b of the surface 24a of the overhang portion 24, may be formed. Accidents due to the cohesion of the adhesive can be prevented, and the tip 14a of the fixed substrate 14 can be reliably bonded to the overhang portion 24.

In the above-described embodiment, the expanding portion 26a is formed for each groove 26 and the adhesive is individually injected into each groove 26. However, as shown in FIGS. As described above, one expanding portion 26d is formed so as to communicate with the upper ends of the plurality of grooves 26, for example, three grooves, and the volume is injected by the plurality of grooves 26 communicating with one expanding portion 26d. By setting the size corresponding to a proper amount of adhesive, the number of times of injection of the adhesive can be reduced and the work efficiency can be improved.

Further, according to this embodiment, the grooves 26 can be arranged at a pitch of 2 mm or less, preferably 1.5 mm or less, as compared with the case where the expanded portions are formed in the grooves 26. .

Therefore, the grooves 26 are formed on the entire surface of the wall surface 27 at such a narrow pitch, and the plurality of grooves 2 are formed.
If one expanding portion 26d is communicated with 6 and formed, the operating speed of the dispenser can be adjusted without the man-hours required to inject the adhesive, and the expanding portion 26d functions as a reservoir to adjust the absorption speed from the groove 26. Since a predetermined amount of the adhesive can be sequentially injected together, the efficiency of the bonding work can be dramatically improved, and the adhesive can be surely permeated into the bonding regions of the wall surface 27 and the overhang portion 24.

[0040]

As described above, according to the present invention ,
The adhesive penetrates the gap between the back surface of the fixed substrate and the wall surface of the frame and the space between the tip and the overhang portion by capillary force so that the adhesive can be securely fixed. The difference in thermal expansion caused by the difference in material can be limited to the portion corresponding to the thickness of the overhang portion of the frame, and the deformation of the pressure generating chamber due to the temperature change can be suppressed as small as possible.

At the same time, since the entire fixed substrate is fixed to the frame, the area of the adhesive layer is expanded to secure the adhesive strength, and the reaction force of the piezoelectric vibrator from the elastic plate can be received by the entire frame.

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing an embodiment of an ink jet recording head of the present invention.

FIG. 2 is a view showing a cross-sectional structure of the same device.

3A and 3B are views showing an embodiment of a frame with a structure of a cross section orthogonal to a wall surface facing a fixed substrate and a cross section parallel to the wall surface, respectively.

FIG. 4 is an enlarged perspective view showing the structure near the opening of the same frame.

FIG. 5 is a diagram showing a structure of a tip of a piezoelectric vibrator unit and a state of being inserted in a frame.

FIG. 6 is a view showing another embodiment of the present invention as a sectional structure in the vicinity of one piezoelectric vibrator.

FIG. 7 is a view showing another embodiment of the present invention as a sectional structure in the vicinity of one vibrator.

FIG. 8 is a diagram showing a structure of a wall surface of a frame of the recording head.

FIG. 9 is a cross-sectional view showing an example of a conventional inkjet recording head using a piezoelectric vibrator of a longitudinal vibration mode.

[Explanation of symbols]

1 nozzle plate 2 nozzle openings 3 Channel forming plate 4 elastic plate 5 Pressure generation chamber 8 Piezoelectric vibrator 9 Thick part 10 Thin part 11 frame opening 14 Fixed board 14a tip 14b slope 16 transducer unit 17 Channel unit 20 frames 23 windows 24 Overhang part 25 Transducer unit accommodation chamber 26 Groove for injection of adhesive 27 walls

Continuation of front page (56) Reference JP-A-5-220956 (JP, A) JP-A-55-109668 (JP, A) JP-A-62-36478 (JP, A) JP-A-59-94495 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16

Claims (11)

(57) [Claims] 1. A plurality of piezoelectric vibrators, in which piezoelectric materials and conductive layers are alternately laminated, which operate in a longitudinal vibration mode, a nozzle plate having nozzle openings, a flow path forming a pressure generating chamber and a reservoir. An ink jet recording head comprising: a forming plate; an elastic plate that contacts the tip of the piezoelectric vibrator; and a frame that fixes the piezoelectric vibrator and the flow path unit. A vibrator is fixed to a fixed substrate extending from a rear end of the piezoelectric vibrator to a front end region via the rear end plate of the piezoelectric vibrator rear end region and the fixed substrate rear end region, and The frame has an opening at one end for inserting the piezoelectric vibrator together with the fixed substrate, a wall surface facing the back surface of the fixed substrate, an overhang portion facing the front end surface of the fixed substrate, and the opening. A groove for injecting an adhesive formed so as to extend from the wall surface to the overhang portion in the vicinity of, and the fixed substrate is fixed to the frame by the adhesive injected into the groove, and the plurality of piezoelectric elements are provided. The remaining portion of the vibrator, which is not fixed to the rear end plate, forms a free end , and the free end on the front end side of the fixed substrate.
An ink jet recording head in which a front end portion of the sheet is in contact with the flow path unit. 2. A wedge-shaped gap that expands upward is formed on the facing surface between the fixed substrate and the frame.
The ink jet recording head according to 1. 3. The ink jet recording head according to claim 1, wherein a plurality of the grooves are formed so as to be symmetrical with respect to the arrangement direction. 4. The ink jet recording head according to claim 1, wherein the grooves are formed at a pitch of 2 mm or less. 5. The ink jet recording head according to claim 1, wherein the groove is formed partway in the overhang portion. 6. The ink jet recording head according to claim 1, wherein the groove is formed up to the vicinity of the overhang portion. 7. The ink jet recording head according to claim 1, wherein an expanded portion for injecting an adhesive is formed on the opening side of the groove. 8. The ink jet recording head according to claim 7, wherein the expanded portion for injecting the adhesive is formed so as to communicate with a plurality of the grooves. 9. The ink jet recording head according to claim 1, wherein recesses for guiding the fixed substrate are formed on both sides of the surface on which the groove is formed. 10. The ink jet recording head according to claim 1, wherein a tip end of the fixed substrate is formed in a wedge shape so that the piezoelectric vibrator mounting side has an inclined surface. 11. The plurality of piezoelectric vibrators are mounted on a fixed substrate extending from a rear end of the plurality of piezoelectric vibrators to a front end region, and a rear end region of the piezoelectric vibrator and a rear end of the fixed substrate. A vibrator unit in which a region is fixed via a rear end plate, a flow path unit including an elastic plate having a thick portion with which the tip of the piezoelectric vibrator contacts, and the piezoelectric vibrator is fixed to one end. An opening to be inserted together with the substrate and a tip of the piezoelectric vibrator of the vibrator unit at the other end.
Parts to expose the, and said overhang portion facing the distal end surface of the fixed substrate, a frame and a groove formed for adhesive injection so as to extend from the vicinity of the overhang portion is formed of the opening, consisting of In the method for manufacturing an ink jet recording head, a step of inserting the piezoelectric vibrator unit into the frame through the opening so that a front end surface of the fixed substrate contacts the overhang portion; and an adhesive agent in a groove of the frame. Of the ink jet recording head, which comprises a step of injecting and diffusing the adhesive into a gap formed between the back surface of the fixed substrate and the wall surface of the frame, and a gap between the front end surface of the fixed substrate and the overhang portion. Production method.