JP3729002B2 - Inkjet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head that ejects ink droplets from nozzle holes in order to record images, characters, and the like on recording paper.
[0002]
[Prior art]
Inkjet printers, which are widely used as recording devices, are configured to record print data such as images and characters by landing ink droplets on a print medium (recording paper). Inkjet recording that ejects ink droplets from nozzle holes A head is provided.
[0003]
The ink jet recording head includes a nozzle plate in which a large number of nozzle holes for ejecting ink droplets are arranged. The nozzle plate is supported by a carriage in a state of facing the recording paper, and extends in the width direction of the recording paper along the guide member. Move (main scan).
[0004]
For example, as disclosed in Japanese Patent Laid-Open No. 6-320725, in a recording head in which ink droplets are ejected by a piezoelectric vibrator, a nozzle plate is bonded to a vibration plate via a spacer. In the spacers, ink channels and pressure chambers are formed in a predetermined pattern, and are integrated into a channel unit to maintain airtightness. A 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 the front end surface of the case. At this time, each piezoelectric chamber is connected to each nozzle hole. The vibrators are in contact with each other, that is, the piezoelectric vibrators are brought into contact with the diaphragm from the opening (window) formed on the front end surface of the case, and the diaphragm of each pressure chamber is vibrated. The pressure fluctuates in this way, thereby causing ink droplets to be appropriately discharged.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional ink jet recording head, the adhesive applied (transferred) to the joint surface at the tip of the case has fluidity. Therefore, when the flow path unit is joined to the case side, the adhesive surface is bonded. The adhesive flows and the adhesive protrudes into the opening facing each piezoelectric vibrator. Then, the adhesive that has flowed out adheres to the elastic partition of the pressure chamber, that is, the elastic sheet of the diaphragm, so that the bending characteristic of the diaphragm is changed, and as a result, the ink ejection characteristics vary in the array of nozzle holes. There is a problem that the printing quality is deteriorated. In particular, in the case of color printing, the recording head has a structure in which a plurality of nozzle hole arrays in which a large number of nozzle holes are arrayed are arranged, and the interval between adjacent nozzle hole arrays is reduced for miniaturization. The influence of the problem that the agent flows out is great.
[0006]
The present invention has been made in view of the above circumstances, and its purpose is to reduce the flow of adhesive to the diaphragm side constituting a part of the pressure chamber when the flow path unit and the case are joined. It is an object of the present invention to provide an ink jet recording head that can maintain a good bending characteristic of a vibration plate and can prevent deterioration in printing quality.
[0007]
[Means for Solving the Problems]
The present invention has been proposed in order to achieve the above-described object.In the first aspect of the present invention, a flow path unit provided with a plurality of nozzle hole arrays, and a joint surface for joining the flow path units, A case having a plurality of openings corresponding to the nozzle hole row, and a housing empty portion communicating with each opening formed therein, and the case is fixed in the housing empty portion of this case, and the output portion at the front end faces the opening. Pressure generating means joined to a diaphragm constituting a part of the pressure chamber in a state, and the diaphragm is displaced by an output portion of the pressure generating means to discharge ink in the pressure chamber from the nozzle hole. In the ink jet type recording head, a rib formed between a plurality of the openings of the case and a recess formed on a joint surface between the channel unit, the recess is opened to the atmosphere, and the case and the channel unit And the joint surface with An ink jet recording head is characterized by comprising a a ventilation passage which extends to the opposite side.
[0008]
According to a second aspect of the present invention, in the ink jet recording head according to the first aspect, a reinforcing material is inserted into the rib portion, and the width of the concave portion is set narrower than the thickness of the reinforcing material. is there.
[0009]
According to a third aspect of the present invention, a concave portion for compliance is formed on the joint surface of the case, the concave portion for compliance is opened to the atmosphere, and a communication path that communicates the concave portion for compliance 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 provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an ink jet recording head of the present invention will be described with reference to the drawings. 1 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 view. FIG. 3 is a cross-sectional view of the recording head 1 cut along the YZ plane of FIG. 1, FIG. 3 is an enlarged cross-sectional view of the main part, and FIG. 4 is a plan view for explaining the joint surface of the case.
[0016]
The ink jet recording head 1 includes a nozzle hole in a nozzle plate 5 constituting a part of a flow path unit 4 by driving a piezoelectric vibrator 3 housed in a plastic box-like case 2 as pressure generating means. 50 is configured to eject ink droplets.
[0017]
The flow path unit 4 has a configuration 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 an empty portion serving as a pressure chamber in a predetermined pattern. In addition, the nozzle plate 5 and the diaphragm 7 are bonded together and integrated to maintain airtightness.
[0018]
The nozzle plate 5 is provided with a plurality of nozzle holes 50 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, in the case 2, two strip-shaped elongated openings 20 are formed in parallel on the joint surface with the flow path unit 4, and the comb-shaped tip of the piezoelectric vibrator 3 faces the openings 20. The tip of each one (output portion) is in contact with a predetermined portion (island portion) of the diaphragm 7.
[0019]
The spacer 6 is formed of a silicon wafer or the like, and by etching the spacer 6, each empty portion is partitioned into a predetermined pattern. As shown in FIGS. 2 and 3, a plurality of spacers 6 communicate with each nozzle hole 50. The pressure chambers 60, the common ink chambers 61, and the partition walls constituting the plurality of ink supply paths 62 connected from the common ink chambers 61 to the pressure chambers 60 are appropriately formed. Note that the ink supply pipe 8 is connected to the common ink chamber 61 through a connection port 63 provided in the vibration plate 7, and ink stored in an ink cartridge (not shown) is supplied.
[0020]
As shown in FIG. 2, the diaphragm 7 has a double structure in which an elastic body film (resin film) 7b such as a PPS film is laminated on a stainless steel plate 7a as a metal plate, and portions corresponding to the pressure chambers 60 are as follows. The stainless steel plate side is etched in an annular shape, and island portions 70 are formed in the ring, and the tip (output portion) of each piezoelectric vibrator 3 is joined to each island portion 70.
[0021]
The piezoelectric vibrator 3 has a plurality of tips (output portions) arranged corresponding to the respective pressure chambers 60, and these form a slit portion in a comb shape at a predetermined pitch on one large piezoelectric vibrator. The base part of the array is fixed to the fixed plate 9 to form a vibrator unit 39. Note that the piezoelectric vibrator 3 shown in the drawing contracts in a direction perpendicular to the stacking direction of the piezoelectric body and the electrodes when charged, pulls the diaphragm 7, expands the pressure chamber 60, and expands and vibrates when discharged. The pressure chamber 60 is contracted by pressing the plate 7. Then, ink droplets are ejected from the nozzle holes 50 using changes in the ink pressure in the pressure chamber 60 accompanying expansion / contraction of the pressure chamber 60.
[0022]
As shown in FIG. 2, the case 2 is formed with a storage space 21 for storing the transducer unit 39, and the storage space 21 is located on the opposite side from the opening 20 on the joint surface with the flow path unit 4. The vibrator unit 39 is inserted in such a posture that the tip of the piezoelectric vibrator 3 faces the opening 20, and the fixing plate 9 is placed at a position where each tip is flush with the opening 20. It is attached by fixing it to. In this embodiment, the storage empty part 21 is formed in two, and the rib part 22 is provided between both. As shown in FIG. 4, a concave portion 23 is provided on a portion sandwiched between both openings 21 of the housing empty portion 21, that is, an end surface of the rib portion 22, on the joint surface of the case 2 with the flow path unit 4. Further, a compliance recess 24 is provided on the opposite surface across the opening 20.
[0023]
The concave portion 23 is a concave portion which is a main component of the present invention, and is formed into a strip shape along the opening 20 for the purpose of minimizing the protrusion of the adhesive during bonding by reducing the application area of the adhesive. Is formed. As shown in FIG. 4, the recess 23 is connected to a communication pipe 10 as an air passage. The communication pipe 10 is formed in the case 2 toward its base, and a pipe end on the base side. Is open to the atmosphere. Therefore, the recess 23 is configured to be constantly at atmospheric pressure via the communication pipe 10 regardless of opening / closing of the opening on the joint surface side.
[0024]
On the other hand, the compliance concave portion 24 is a hollow portion intended to obtain a large compliance by easily deforming the vibration plate 7 easily, and is also formed in a band shape along the opening 20. Thus, the compliance recess 24 is not only different in arrangement from the recess 23 but also has a different purpose and function.
[0025]
With the above configuration, the ink jet recording head 1 of the present embodiment is provided with the concave portion 23 on the joint surface between the case 2 and the flow path unit 4, and therefore the joint area is reduced by the provision of the concave portion 23. The amount of adhesive to be applied (transferred) at the time of joining with the flow path unit 4 is reduced. In addition, since there is a portion that flows into the recess 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 diaphragm 7, particularly the elastic film (elastic sheet) 7 b. Can be reduced. Further, since the recess 23 is opened 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 atmospheric pressure. Therefore, even if the opening of the recess 23 is closed during bonding, there is no problem in that a part of the excess adhesive on the bonding surface flows into the recess 23.
[0026]
As described above, in the present embodiment, in combination with the reduction of the adhesive application area by the concave portion 23, the surplus adhesive that has conventionally flowed out to the two sides of the rib portion 22 is formed on both sides of the concave portion 23. The flow is distributed to a total of four locations on both sides of the rib portion 22, and the flow-out amount per location 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 bending characteristic of the diaphragm 7 can be maintained satisfactorily, thereby preventing a decrease in print quality.
[0027]
Note that the air passage such as the communication pipe 10 that opens the recess 23 to the atmosphere extends in the case 2 in a direction crossing the joint surface, and on the surface of the case 2 opposite to the joint surface or in the case 2. It is preferable to open the pipe end. With this configuration, there is a possibility that the ink attached to the side surface of the case 2 may enter the air passage from this opening, and this can be prevented. That is, when used for a long period of time, ink mist tends to adhere to and accumulate on the side surface of the flow path unit 4 and the vicinity of the case, and there is an effect of preventing the ink from entering the inside of the recording head 1 and adhesion reliability is improved. Rise.
[0028]
Further, as shown in FIG. 5, the air passage may be formed in parallel with the joint surface, and the pipe end may be opened on the side surface of the case 2 near the joint surface. With this configuration, ink attached to the side surface of the case 2 may enter the air passage, but the diaphragm 7 is bonded in a state of covering the air passage. Never reach. However, since the part where the adhesion boundary is exposed to ink increases, it is preferable to open the other part by the communication pipe 10 as in the above-described embodiment, rather than opening the side of the case 2.
[0029]
FIG. 6 shows a second embodiment of the present invention and is a plan view showing the case 2 of the recording head 1 similarly to FIG. In the second embodiment, the recess 23 provided on the end surface of the rib portion 22 is not connected to a separate communication pipe, but instead a connection path 25 connecting the recess 23 and the compliance recess 24 is joined to the case 2. The compliance recess 24 is provided with a communication path 26 connected to the atmosphere to reduce the deformation resistance of the elastic film of the diaphragm 7 as a ventilation path. The recess 23 is opened to the atmosphere via the communication path 25. 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 in the first embodiment can be obtained.
[0030]
FIG. 7 is a plan view showing the case 2 of the recording head 1 as in FIG. 4 according to the third embodiment of the present invention. In the third embodiment, only the recesses 23 are formed on the joint surfaces between the openings 20, that is, the end surfaces of the ribs 22, and since there is no air release to the recesses 23, the amount of adhesive pushed into the recesses 23 is Although it may be less than in the case of the first and second embodiments, the application amount of the adhesive is reduced by providing the recess 23, and the amount flowing into the opening 20 side is expected to be reduced to a smaller amount than before. it can.
[0031]
FIG. 8 shows a fourth embodiment of the present invention and is a plan view showing the case 2 of the recording head 1 similarly to 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, the end surface of the rib portion 22, and the concave portions 27 are sealed by joining the flow path unit 4. Is adopted. In this case, since a large number of the concave portions 27 are provided side by side, it is easy to ensure the rigidity of the case 2, and on the other hand, the operation is the same as that of the third embodiment, and the same effect is obtained.
[0032]
In the case of the present embodiment, a part of the thickness of the diaphragm 7 joined to the joining surface of the case 2 is communicated with each recess 27 and one end is on the side of the case 2 as shown by a one-dot chain line in the figure. An open air groove 65 may be formed to open the air. In order to form the groove 65 in the vibration plate 7, the vibration plate 7 is composed of a laminate of a resin film and a metal plate such as a stainless steel plate. By removing, a groove 65 having a predetermined width can be formed. The plate thickness of a metal plate such as a stainless steel plate is easier to manage the dimensions and contributes to space saving as compared to the case where a recess is formed in the case 2 which is a molded product. In other words, the volume required by adding the flow-out amount of the adhesive and the clearance to the atmosphere is the required volume, but when the recess is formed as a part of the injection molded product, the tolerance becomes larger than in the etching process, Forming the groove 65 by etching the diaphragm 7 requires a smaller area and contributes to space saving.
[0033]
FIG. 9 shows a fifth embodiment of the present invention and is a cross-sectional view of the recording head 1 cut in the same manner as in FIG. In the fifth embodiment, the reinforcing material 11 such as a metal plate is inserted into the rib portion 22, and the width W <b> 1 of the concave portion 23 provided on the rib portion 22 is set to be narrower than the thickness W <b> 2 of the reinforcing material 11. Take. With this configuration, since the width W1 of the recess 23 is narrower than the thickness W2 of the reinforcing material 11, it is easy to ensure the rigidity in the vicinity of the end surface of the rib portion 22 in which the recess 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 material 11 side, sufficient strength can be obtained, and deformation of the flow path unit 4 can be effectively prevented. Therefore, the rib portion 22 can be made thin, and the recording head 1 can be further miniaturized.
[0034]
The pressure generating means is not limited to the piezoelectric vibrator 3 described above, and may be a magnetostrictive element, for example. Further, the number of nozzle rows is not limited to two, but may be a plurality of rows.
[0035]
【The invention's effect】
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 between the rib and the flow path unit located between the plurality of openings of the case, the joint area is reduced by the amount of the concave portion, The amount of adhesive applied when joining with the flow path unit is reduced. For this reason, since the amount of the adhesive flowing into the opening facing the output portion of the pressure generating means is reduced, and there is also a portion flowing into the recess, the amount flowing into the opening side can be further reduced. Therefore, when the flow path unit and the case are joined, it is possible to reduce the flow of the adhesive to the diaphragm side of the pressure chamber, and as a result, it is possible to keep the flexure characteristics of the diaphragm favorable. Thereby, it is possible to prevent a decrease in print quality due to the adhesive adhered to the diaphragm.
[0036]
According to invention of Claim 2, since the recessed part is open | released to air | atmosphere, even if the opening of a recessed part is obstruct | occluded by the flow path unit, the inside of a recessed part can be maintained at atmospheric pressure. Therefore, the adhesive can smoothly flow into the recess.
[0037]
According to the invention of claim 3, since the air passage that connects one end to the concave portion and opens the concave portion to the atmosphere extends in a direction crossing the joint surface of the case, the other end of the air passage is joined to the case. Open at the part away from the surface and open to the atmosphere. Therefore, even if the ink adheres to the vicinity of the flow path unit of the recording head when it is used for a long time, the adhered ink is prevented from penetrating the adhesive through the air passage and entering the inside of the recording head. it can.
[0038]
According to the invention of claim 4, since the reinforcing material is inserted into the rib portion formed between the storage empty portions, and the width of the concave portion is set narrower than the thickness of the reinforcing material, the rigidity of the rib portion, In particular, it is easy to ensure the rigidity of the rib portion near the center portion of the nozzle hole row. Therefore, the compressive force of the rib portion that acts when the piezoelectric vibrator contracts can be reliably received.
[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 of FIG.
FIG. 3 is an enlarged cross-sectional view of a main part.
FIG. 4 is a plan view for explaining a joint surface of the case.
FIG. 5 is a plan view of the joint surface of the case showing the main part of the embodiment in which the air passage is opened on the side surface of the case.
FIG. 6 is a plan view of a joint surface of a case showing the 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 showing a fourth embodiment.
FIG. 9 is a cross-sectional view of a recording head showing a fifth embodiment in which a reinforcing material is inserted in the rib portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inkjet 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 empty part 22 Rib part 23 Concave part 24 For compliance Recess 25 communication path 26 communication path 27 recess 39 transducer unit 50 nozzle hole 60 pressure chamber 61 common ink chamber 62 ink supply path 63 connection port 65 groove 70 island section

Claims (3)

A flow path unit provided with a plurality of nozzle hole rows;
A case in which a plurality of openings corresponding to the nozzle hole rows are formed on the joint surface for joining the flow path units, and a housing empty portion communicating with each opening is formed inside,
A pressure generating means that is fixed in the housing empty portion of the case and is 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 for discharging the ink in the pressure chamber from the nozzle hole by displacing the diaphragm by the output portion of the pressure generating means,
A recess formed on a joint surface between the rib and the flow path unit located between the plurality of openings of the case;
An ink jet recording head comprising: an air passage that opens the concave portion to the atmosphere and extends on a side opposite to a joint surface between the case and the flow path unit.   2. The ink jet recording head according to claim 1, wherein a reinforcing material is inserted into the rib portion, and the width of the concave portion is set narrower than the thickness of the reinforcing material.   The compliance concave portion is formed on the joint surface of the case, the compliance concave portion is opened to the atmosphere, and a communication path is formed on the joint surface to communicate the compliance concave portion and the concave portion. Or an ink jet recording head described in 2;

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