JP2001162792A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head in which print quality is prevented from lowering by minimizing outflow of adhesive to the diaphragm side of a pressure chamber at the time of bonding a channel unit and a case thereby sustaining good flexure characteristics of the diaphragm. SOLUTION: Two openings 20 corresponding to nozzle hole arrays are made in the bonding face of a channel unit 4 and a case 2 and a recess 23 is made in the bonding face between the opening of the case.

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 discharging ink droplets from nozzle holes for recording images, characters and the like on recording paper.

[0002]

2. Description of the Related Art An ink jet printer, which is frequently used as a recording apparatus, is configured to record print data such as images and characters by landing ink droplets on a print medium (recording paper). An ink jet recording head for discharging is provided.

This ink jet recording head has a nozzle plate in which a large number of nozzle holes for discharging ink droplets are arranged. The nozzle plate is supported by a carriage in a state where the nozzle plate faces the recording paper. Move (main scan) in the width direction.

For example, as disclosed in Japanese Patent Application Laid-Open No. 6-320725, in a recording head in which ink droplets are driven to be driven by a piezoelectric vibrator, a nozzle plate is bonded to a vibration plate via a spacer. The spacer is formed with a predetermined pattern of an ink flow path and an empty space serving as a pressure chamber, and is integrated into a flow path unit to maintain airtightness. Then, the vibrator unit in which a plurality of piezoelectric vibrators are arranged is housed in a box-shaped case, and a flow path unit is joined to a tip surface of the case. At this time, each piezoelectric chamber is connected to each of the nozzle holes. The vibrators are in contact with each other, that is, each piezoelectric vibrator is brought into contact with the vibrating plate through an opening (window) formed in the front end surface of the case, and the vibrating plate of each pressure chamber is vibrated. , Causing pressure fluctuations, thereby appropriately discharging ink droplets.

[0005]

However, in the above-mentioned conventional ink jet recording head, since the adhesive applied (transferred) to the joint surface at the front end of the case has fluidity, the flow path unit is joined to the case side. At this time, the adhesive flows over the joint surface and flows out to the opening facing each piezoelectric vibrator. The adhesive that has flowed out adheres to the elastic partition of the pressure chamber, that is, the elastic sheet of the vibration plate, and solidifies, so that the bending characteristics of the vibration plate are changed. As a result, the ink ejection characteristics vary in the row of nozzle holes. This causes a problem that print quality is deteriorated. In particular, in the case of color printing, the recording head employs a configuration in which multiple rows of nozzle holes are arranged, and the spacing between adjacent nozzle hole rows is narrowed for miniaturization. The effect of the problem of the agent flowing out is significant.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive to a diaphragm constituting a part of a pressure chamber when joining a flow path unit and a case. An object of the present invention is to provide an ink jet recording head which can reduce the flow-out, maintain good deflection characteristics of the diaphragm, and prevent a decrease in print quality.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and the present invention is directed to a flow path unit provided with a plurality of nozzle hole arrays and a flow path unit having the same. A case in which a plurality of openings corresponding to the nozzle hole rows are provided on the joining surface for joining the path units, and a storage space portion communicating with each opening is formed inside the case, and the case is fixed in the storage space portion of the case, and the output of the tip is Pressure generating means joined to a diaphragm constituting a part of the pressure chamber in a state where the portion faces the opening, and the diaphragm is displaced by an output portion of the pressure generating means to displace the diaphragm from the nozzle hole. An ink jet recording head for discharging ink in a pressure chamber, wherein a concave portion is formed on a joint surface located between openings of a case.

According to a second aspect of the present invention, there is provided the ink jet recording head according to the first aspect, wherein the concave portion is open to the atmosphere.

According to a third aspect of the present invention, a ventilation path having one end connected to the concave portion and opening the concave portion to the atmosphere extends in a direction crossing the joint surface of the case. 2. The ink jet recording head according to item 1.

According to a fourth aspect of the present invention, a reinforcing member is inserted into a rib portion formed between the storage cavities,
4. The ink jet recording head according to claim 1, wherein the width of the recess is set smaller than the thickness of the reinforcing material.

According to a fifth aspect of the present invention, a compliance concave portion is formed on a joint surface of a case, the compliance concave portion is opened to the atmosphere, and a communication path connecting the compliance concave portion and the concave portion is formed on the joint surface. The ink jet recording head according to claim 1, wherein the ink jet recording head is formed.

According to a sixth aspect of the present invention, the pressure generating means is a pressure oscillator.
An inkjet recording head according to any one of the above.

The ink jet type according to any one of claims 1 to 6, wherein the recess is open to the atmosphere through a groove formed in the diaphragm. It is a recording head.

According to another aspect of the present invention, the diaphragm includes:
8. The ink jet recording head according to claim 7, wherein the metal plate and the resin film are laminated, and the groove is formed by etching the metal plate.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an ink jet recording head according to the present invention will be described with reference to the drawings. FIG.
4 to 4 show an embodiment of an ink jet recording head 1 (hereinafter, referred to as a recording head 1) according to the present invention, FIG. 1 is a perspective view showing the recording head 1 in a partially exploded manner, and FIG. FIG. 3 is a cross-sectional view of the recording head 1 taken along the YZ plane in FIG. 1, FIG. 3 is an enlarged cross-sectional view of a main part, and FIG. 4 is a plan view illustrating a joint surface of the case.

The ink jet recording head 1 is driven by a piezoelectric vibrator 3 housed in a plastic box-shaped case 2 as a pressure generating means. Ink droplets are ejected from the nozzle holes 50 of the ink jet printer.

The flow path unit 4 has a structure in which a nozzle plate 5, a spacer 6, and a vibration plate 7 are laminated and laminated, and the spacer 6 is formed with an ink flow path and a space serving as a pressure chamber in a predetermined pattern. Nozzle plate 5
The airtightness is maintained by laminating the vibration plate 7 and the vibration plate 7 vertically.

In the nozzle plate 5, a plurality of nozzle holes 50 are provided in a row at a pitch corresponding to the dot formation density. In the present embodiment, two rows of nozzle holes 50 (nozzle hole rows) are provided in parallel. Correspondingly, two elongated strip-shaped openings 20 are formed in the case 2 on the joint surface with the flow path unit 4 in parallel.
Of the piezoelectric vibrator 3 faces from the
The end (output portion) of the book is configured to contact a predetermined portion (island portion) of the diaphragm 7.

The spacers 6 are formed from a silicon wafer or the like, and each of the vacant spaces is partitioned into a predetermined pattern by etching the silicon wafers. As shown in FIG. 2 and FIG. A plurality of communicating pressure chambers 6
0, a common ink chamber 61, and partition walls constituting a plurality of ink supply paths 62 connected from the common ink chamber 61 to each pressure chamber 60 are appropriately formed. In addition, in the common ink chamber 61,
The ink supply pipe 8 is connected through a connection port 63 opened in the vibration plate 7, and the ink stored in an ink cartridge (not shown) is supplied.

The vibration plate 7 has a double structure in which an elastic film (resin film) 7b such as a PPS film is laminated on a stainless plate 7a as a metal plate as shown in FIG. The stainless steel plate side is etched in a ring shape to form an island portion 70 in the ring, and the tip (output portion) of each piezoelectric vibrator 3 is joined to each island portion 70.

The piezoelectric vibrator 3 has a plurality of tips (output portions) arranged corresponding to the respective pressure chambers 60, and these are arranged in a single large piezoelectric vibrator in a comb-shaped slit portion at a predetermined pitch. Are formed, and the base of the array is fixed to the fixing plate 9 to form the vibrator unit 39. When charged, the piezoelectric vibrator 3 shown in the drawing contracts in a direction orthogonal to the lamination direction of the piezoelectric body and the electrode, pulls the vibrating plate 7 to expand the pressure chamber 60, and expands when discharged to vibrate. The pressure chamber 60 is contracted by pressing the plate 7. The nozzle hole 50 is formed by utilizing a change in the ink pressure in the pressure chamber 60 accompanying expansion and contraction of the pressure chamber 60.
To eject ink droplets.

As shown in FIG. 2, the case 2 is formed with a storage space 21 for housing the vibrator unit 39, and the storage space 21 extends from the opening 20 on the joint surface with the flow path unit 4. The vibrator unit 39 is inserted in such a manner that the front end of the piezoelectric vibrator 3 faces the opening 20, and the fixed plate 9 is stored at a position where each front end is flush with the opening 20. It is attached by being fixed to the inner wall of 21. In the present embodiment, two storage cavities 21 are formed, and a rib 22 is provided between the two.
As shown in FIG. 4, a concave portion 23 is provided on the joint surface of the case 2 with the flow path unit 4, as shown in FIG. In addition, a compliance recess 24 is provided on the opposite surface across the opening 20.

The concave portion 23 is a concave portion which is a main component of the present invention, and the opening 2 is provided for the purpose of minimizing the protrusion of the adhesive at the time of bonding by reducing the adhesive application area.
It is formed in an elongated strip shape along 0. This recess 2
3, a communication pipe 10 as an air passage, as shown in FIG.
The communication pipe 10 is formed inside the case 2 toward the base, and the pipe end is open to the atmosphere on the side of the base. Therefore, the recess 23 is configured to be always at the atmospheric pressure via the communication pipe 10 regardless of the opening and closing of the opening on the joint surface side.

On the other hand, the concave portion 24 for compliance
The concave portion is intended to obtain a large compliance by easily deforming the diaphragm 7 largely, and is also formed in a band shape along the opening 20. In this manner, the compliance recess 24 not only has a different arrangement from the recess 23 but also has a different purpose and function.

With the above configuration, in the ink jet recording head 1 according to the present embodiment, the concave portion 23 is provided on the joint surface between the case 2 and the flow path unit 4, and the joint area is reduced by the provision of the concave portion 23. The amount of adhesive applied (transferred) at the time of joining the case 2 and the flow path unit 4 is reduced. In addition, since some of the adhesive flows into the concave portion 23 at the time of joining, the amount of the adhesive that flows into the opening 20 facing the output portion of the piezoelectric vibrator 3 and adheres to the vibration plate 7, particularly the elastic film (elastic sheet) 7b. Can be reduced. Further, since the recess 23 is open to the atmosphere via the communication pipe 10, even if the opening of the recess 23 is entirely sealed by the diaphragm 7 when the flow path unit 4 is joined, the pressure in the recess 23 is large. Maintain pressure. Therefore, even if the opening of the concave portion 23 is closed at the time of joining, there is no problem in that a part of the excess adhesive on the joining surface flows into the concave portion 23.

As described above, in the present embodiment, the excess adhesive which has conventionally flowed out to two locations on both sides of the rib portion 22 is combined with the reduction of the adhesive application area by the concave portion 23. And flows out in a total of four places on both sides of the rib portion 22 and on both sides of the rib portion 22, so that the amount of flow out at one place including the opening 20 side can be significantly reduced. Therefore, when the flow path unit 4 and the case 2 are joined, the flow of the adhesive to the elastic film of the pressure chamber 60 can be reduced. For this reason, the deflection characteristic of the diaphragm 7 can be kept good, and thereby, a decrease in print quality can be prevented.

The communication pipe 10 for opening the recess 23 to the atmosphere is provided.
The air passage such as extends inside the case 2 in a direction crossing the joint surface, and the surface of the case 2 and the case 2 opposite to the joint surface.
It is preferable to open the tube end inside the tube. With such a configuration, there is a possibility that the ink attached to the side surface of the case 2 may enter the ventilation path from this opening, and this can be prevented. That is, when used for a long period of time, the ink mist easily adheres to and accumulates on the flow path unit 4 and the side surface of the case in the vicinity of the flow path unit 4. Increase.

Further, as shown in FIG. 5, an air passage may be formed in parallel with the joint surface, and the pipe end may be opened on the side of the case 2 near the joint surface. With such a configuration, there is a possibility that the ink attached to the side surface of the case 2 may enter the air passage.
Since the vibration plate 7 is adhered so as to cover the ventilation path, it does not reach the inside of the case 2 such as the opening 20 side. However, since the portion where the bonding boundary is exposed to the ink increases, it is preferable to open the other portion by the communication pipe 10 as in the above embodiment, rather than opening the side surface of the case 2.

FIG. 6 is a plan view showing a second embodiment of the present invention, in which the case 2 of the recording head 1 is shown similarly to FIG. In the second embodiment, a connecting passage connecting the concave portion 23 and the concave portion 24 for compliance is connected to the concave portion 23 provided on the end surface of the rib portion 22 without connecting a separate communication pipe. In the compliance recess 24, a communication path 26 leading to the atmosphere is provided as a ventilation path in order to reduce the deformation resistance of the elastic film of the diaphragm 7, so that the communication path 26 Connection 25
The concave portion 23 is opened to the atmosphere via the. As described above, in the second embodiment, since the concave portion 23 can be opened to the atmosphere without separately providing the communication pipe 10, the same operation and effect as those of the first embodiment can be obtained.

FIG. 7 shows a third embodiment of the present invention, and is a plan view showing the case 2 of the recording head 1 as in FIG. In the third embodiment, only the concave portion 23 is formed on the joint surface between the openings 20, that is, the end surface of the rib portion 22. Since the concave portion 23 is not open to the atmosphere, the amount of the adhesive extruded into the concave portion 23 is limited. Although it is conceivable that the amount is smaller than that in the first and second embodiments, the provision of the concave portion 23 reduces the amount of adhesive applied, and is expected to suppress the amount flowing into the opening 20 to a smaller amount than in the related art. it can.

FIG. 8 shows a fourth embodiment of the present invention, and is a plan view showing the case 2 of the recording head 1 in the same manner as FIG. In the fourth embodiment, a plurality of small concave portions 27 are provided side by side on the joint surface between the openings 20, that is, on the end surface of the rib portion 22, and these concave portions 27 are sealed by joining the flow path unit 4. Has been adopted. In this case, since the small number of the concave portions 27 are provided side by side, the rigidity of the case 2 can be easily ensured. On the other hand, the operation is the same as that of the third embodiment, and the same effect is obtained.

In the case of the present embodiment, a part of the thickness of the diaphragm 7 joined to the joint surface of the case 2 communicates with each recess 27 as shown by a dashed line in FIG. 2
An open-to-atmosphere groove 65 may be formed on the side surface to open to the atmosphere. In order to form the groove 65 in the vibration plate 7, since the vibration plate 7 is formed of a laminated body of a resin film and a metal plate such as a stainless plate, the stainless plate is etched to remove a portion overlapping each recess 27. By removing, a groove 65 having a predetermined width can be formed. The thickness of a metal plate such as a stainless steel plate
Compared to the case where the concave portion is formed in the case 2 which is a molded product, the size can be easily controlled, and the space can be saved. In other words, the volume obtained by adding the amount of the adhesive flowing out and the gap open to the atmosphere is the required volume, but if a concave portion is formed as a part of the injection molded product, the tolerance becomes larger than in the case of etching, Forming the groove 65 by etching the diaphragm 7 requires a smaller area,
Contributes to space saving.

FIG. 9 is a sectional view showing a fifth embodiment of the present invention, in which the recording head 1 is cut similarly to FIG. Fifth
In the embodiment, the reinforcing member 11 such as a metal plate is inserted into the rib portion 22, and the concave portion 23 provided on the rib portion 22 is provided.
Is set to be smaller than the thickness W2 of the reinforcing member 11. With this configuration, the width W1 of the concave portion 23 is smaller than the thickness W2 of the reinforcing member 11, so that it is easy to secure the rigidity near the end face of the rib portion 22 in which the concave portion 23 is formed. When this is done, the compressive force acting on the rib portion 22 from the diaphragm 7 side can be reliably transmitted to the reinforcing member 11 side, sufficient strength can be obtained, and deformation of the flow path unit 4 can be effectively prevented. Therefore, the rib 2
2 can be made thinner, and the size of the recording head 1 can be further reduced.

The pressure generating means is not limited to the above-described piezoelectric vibrator 3, but may be, for example, a magnetostrictive element. Further, the number of nozzle rows is not limited to two, but may be a plurality of rows.

[0035]

As described above, the ink jet recording head of the present invention has the following effects. According to the first aspect of the present invention, since the concave portion is formed in the joint surface located between the openings of the case, the joint area is reduced by the provision of the concave portion, and the joint is applied when the case and the flow path unit are joined. The amount of adhesive is reduced. For this reason, the amount of the adhesive flowing into the opening facing the output portion of the pressure generating means is reduced, and some of the adhesive flows into the concave portion, so that the amount flowing into the opening can be further reduced. Therefore, at the time of joining the flow path unit and the case, the flow of the adhesive to the diaphragm side of the pressure chamber can be reduced, and as a result, the deflection characteristics of the diaphragm can be kept good. Thus, it is possible to prevent a decrease in print quality due to the adhesive attached to the diaphragm.

According to the second aspect of the present invention, since the recess is open to the atmosphere, the inside of the recess can be maintained at the atmospheric pressure even if the opening of the recess is closed by the flow path unit. Therefore, the adhesive can flow smoothly into the recess.

According to the third aspect of the present invention, the ventilation path, one end of which is connected to the concave portion and opens the concave portion to the atmosphere, extends in the direction crossing the joint surface of the case. Open at a location away from the joint surface of the case and open to the atmosphere.
Therefore, even if the ink is used for a long time and adheres to the vicinity of the flow path unit of the recording head, the adhered ink is prevented from penetrating the adhesive through the air passage and entering the inside of the recording head. it can.

According to the fourth aspect of the present invention, the reinforcing member is inserted into the rib portion formed between the storage cavities, and the width of the concave portion is set smaller than the thickness of the reinforcing member. , Especially the rigidity of the ribs near the center of the nozzle hole row. Therefore, it is possible to reliably receive the compressive force of the rib portion that acts when the piezoelectric vibrator contracts.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a part of an ink jet recording head.

FIG. 2 is a cross-sectional view of the recording head taken along the YZ plane in FIG.

FIG. 3 is an enlarged sectional view of a main part.

FIG. 4 is a plan view illustrating a joint surface of a case.

FIG. 5 is a plan view of a joint surface of the case showing a main part of the embodiment in which a ventilation path is opened to a side surface of the case.

FIG. 6 is a plan view of a joint surface of a case showing a main part of the second embodiment.

FIG. 7 is a plan view of a joint surface of a case showing a third embodiment.

FIG. 8 is a plan view of a joint surface of a case according to a fourth embodiment.

FIG. 9 is a sectional view of a recording head showing a fifth embodiment in which a reinforcing material is inserted into a rib portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet recording head 2 Case 3 Piezoelectric vibrator 4 Flow path unit 5 Nozzle plate 6 Spacer 7 Vibration plate 8 Ink supply pipe 9 Fixing plate 10 Communication pipe 11 Reinforcement material 20 Opening 21 Storage space 22 Rib 23 Depression 24 Compliance Concave section 25 communication path 26 communication path 27 concave section 39 vibrator unit 50 nozzle hole 60 pressure chamber 61 common ink chamber 62 ink supply path 63 connection port 65 groove 70 island section

Claims (8)

[Claims] 1. A flow path unit having a plurality of nozzle hole arrays, and a storage space having a plurality of openings corresponding to the nozzle hole arrays on a joining surface for joining the flow path units, and communicating with each of the openings. And a pressure generating means fixed in the storage space of the case and joined to a diaphragm constituting a part of the pressure chamber with the output portion at the tip facing the opening, In the ink jet recording head which displaces the diaphragm by the output portion of the pressure generating means and discharges the ink in the pressure chamber from the nozzle hole, it is preferable that the concave portion is formed on the joint surface located between the openings of the case. Characteristic inkjet recording head. 2. The ink jet recording head according to claim 1, wherein the concave portion is open to the atmosphere. 3. An ink jet recording head according to claim 2, wherein a ventilation path having one end connected to said concave portion and opening said concave portion to the atmosphere is extended in a direction crossing a joint surface of said case. . 4. The method according to claim 1, wherein a reinforcing material is inserted into a rib portion formed between the storage cavities, and a width of the concave portion is set to be smaller than a thickness of the reinforcing material. The inkjet recording head according to any one of the above. 5. A compliance concave portion is formed on a joint surface of the case, the compliance concave portion is opened to the atmosphere, and a communication path connecting the compliance concave portion and the concave portion is formed on the joint surface. The ink jet recording head according to claim 1. 6. The ink jet recording head according to claim 1, wherein said pressure generating means is a piezoelectric vibrator. 7. The device according to claim 1, wherein the recess is open to the atmosphere via a groove formed in the diaphragm.
7. The ink jet recording head according to any one of items 1 to 6. 8. The ink jet recording head according to claim 7, wherein the diaphragm has a structure in which a metal plate and a resin film are laminated, and the groove is formed by etching the metal plate.