JP2014058079A - Droplet discharge head and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet discharge head capable of inhibiting warpage, and to provide an image formation device.SOLUTION: A droplet discharge head 10 includes: a driving control part, such as a drive IC 20, which controls driving of pressure increase means, such as a piezoelectric element 14, for increasing a pressure in a liquid chamber such as an individual liquid chamber 2 and causing a liquid in the liquid chamber to be discharged from a nozzle 11a; a member, such as a holding substrate 15, which has a housing wall 24a of a housing part 24 in which the driving control part is housed; and a sealing material 17 which seals a connection part between the pressure increase means and the driving control part. The droplet discharge head 10 has a structure where the sealing material 17 is provided in a gap between the housing wall 24a and the driving control part. The droplet discharge head 10 includes a contractive force absorbing part, such as a side wall part 24c, for absorbing a contractive force of the sealing material 17, which occurs during the manufacturing, and inhibiting warpage of the droplet discharge head 10.

Description

  The present invention relates to a droplet discharge head and an image forming apparatus.

  Printers, fax machines, copiers, plotters, or image forming apparatuses that combine multiple functions of these, for example, are equipped with a droplet ejection head that ejects ink droplets, and ink droplets are printed on paper while conveying media There is an ink jet recording apparatus that forms an image by adhering. The medium here is also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, a recording paper, and the like are also used synonymously. The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics. The image formation is not only giving an image having a meaning such as a character or a figure to the medium but also giving an image having no meaning such as a pattern to the medium (simply ejecting a droplet). Also means. The ink is not limited to so-called ink, and is not particularly limited as long as it becomes liquid when ejected. For example, the ink is a generic term for liquids including DNA samples, resists, pattern materials, and the like. Use.

  As a droplet discharge head, for example, as described in Patent Document 1, a plurality of nozzles, a plurality of individual liquid chambers communicating with each nozzle, a pressure increasing unit that pressurizes each individual liquid chamber, A configuration including a common liquid chamber communicating with the liquid chamber is known. As the pressure increasing means, for example, a heater is installed in the individual liquid chamber to vaporize the liquid in the individual liquid chamber to increase the pressure in the individual liquid chamber, an actuator is installed in the individual liquid chamber, and the individual liquid chamber is deformed. There is an actuator system that boosts the pressure in the individual liquid chamber. Examples of the actuator method include a piezoelectric element method and an electrostatic method depending on the type of actuator.

FIG. 14 is a longitudinal sectional view of the droplet discharge head 100 described in Patent Document 1. As shown in FIG.
In this patent document 1, an electrostatic actuator that electrostatically vibrates the diaphragm 103 is used as a boosting unit that boosts the individual liquid chamber 102.
As shown in FIG. 14, the droplet discharge head 100 accommodates a nozzle substrate 111 in which two nozzle rows composed of a plurality of nozzles 101 are formed in parallel with each other, a wall surface of a plurality of individual liquid chambers 102, and a drive IC 120 described later. It has the individual liquid chamber substrate 112 on which the side wall 124a of the accommodating portion 124 and the like are formed. In addition, it has a cavity substrate 113 provided with a plurality of diaphragms 103 constituting a part of the wall surface of each individual liquid chamber 102. Furthermore, it has an electrode substrate 114 provided corresponding to the plurality of diaphragms 103 of the cavity substrate 113 and formed with individual electrodes 104 facing the diaphragm 103 with a predetermined gap.

  One end of each individual electrode 104 is connected to the driving IC 120 by a connection unit 119, and a driving signal is supplied from the driving IC 120. Each individual electrode 104, the drive IC 120, and the connection portion 119 are sealed with a sealing material 105, and a short circuit due to moisture adhering to the connection portion 119 is prevented.

FIG. 15 is a diagram illustrating a manufacturing process of the droplet discharge head 100 described in Patent Document 1.
First, as shown in FIG. 15A, the driving IC 120 is connected to the electrode substrate 114 so as to be connected to each individual electrode 104 exposed from the hole 121 at the center in the drawing of the cavity substrate 113 bonded to the electrode substrate 114. Implement above.

  Next, as shown in FIG. 15B, a sealing material 105 is applied to the connection portion 119 between the individual electrode 104 and the drive IC 120 with a needle (not shown) to seal the connection portion 119.

  Next, as shown in FIG. 15C, the individual liquid chamber substrate 112 on which the wall surface of the individual liquid chamber 102 and the wall surface 124 a of the accommodating portion 124 in which the driving IC 120 is accommodated is bonded to the cavity substrate 113. Then, as shown in FIG. 15D, the droplet discharge head 100 is formed by bonding the nozzle substrate 111 in which the nozzle holes 101 are formed to the individual liquid chamber substrate 112 using an adhesive or the like. .

  However, the droplet discharge head 100 described in Patent Document 1 has the following problems. That is, in the droplet discharge head 100 described in Patent Document 1, the drive IC 120 is connected to the electrode substrate 114, the connection portion 119 is sealed with the sealing material member 105, and then the storage portion that stores the drive IC 120. The individual liquid chamber substrate 112 on which the side wall 124a is formed is bonded. For this reason, when the sealing material 105 is applied to the connection portion 119, the sealing material 105 may adhere to the portion X of the cavity substrate 113 shown in FIG. If the portion of the cavity substrate 113 to which the sealing material 105 is attached is a joint portion with the individual liquid chamber substrate 112, a bonding failure may occur at the portion to which the sealing material 105 is attached. Therefore, as shown in FIG. 15C, it is necessary to join the individual liquid chamber substrate 112 to the cavity substrate 113 at a position somewhat away from the position where the sealing material 105 is applied. This is a problem that the gap between the side wall 124a forming the 124 and the driving IC 120 becomes large, and the droplet discharge head 100 is enlarged.

Therefore, the applicant of the present application is developing a droplet discharge head manufactured by the following process.
16 and 17 are diagrams showing a manufacturing process of the droplet discharge head 10 ′ under development.
The droplet discharge head 10 ′ under development shown in FIG. 16 uses a piezoelectric actuator system using a piezoelectric element 14 composed of a lower electrode 14a, a piezoelectric body 14b, and an upper electrode 14c as a boosting means. In addition, the droplet discharge head under development differs from the droplet discharge head disclosed in Patent Document 1 shown in FIG. 14 in that the storage unit 24 that stores a drive IC as a drive control unit is provided as an individual liquid chamber substrate. 12 is provided on a holding substrate 15 that holds 12 or the like.

  In the droplet discharge head 10 ′ under development, as shown in FIG. 16A, a thin film-like diaphragm 13 is laminated on the individual liquid chamber substrate 12 before the individual liquid chambers are formed. ing. On the vibration plate 13, a plurality of piezoelectric elements 14 including a lower electrode 14 a, a piezoelectric body 14 b, and an upper electrode 14 c are located at positions corresponding to a plurality of individual liquid chambers formed on the individual liquid chamber substrate 12 in a later step. Is formed. In the center of the figure, a connection electrode 30 of the piezoelectric element 14 is provided.

  As shown in FIG. 16B, the holding substrate 15 on which the side wall 24a of the accommodating portion that accommodates the drive IC 20 as the drive control portion is formed is bonded to the substrate on which the piezoelectric element 14 is provided. Next, the drive IC 20 is inserted into the housing portion 24, and the drive IC 20 is connected to the connection electrode 30 of the piezoelectric element 14.

  The droplet discharge head 10 ′ under development is bonded to the holding substrate 15 on which the side wall 24 a of the accommodating portion 24 that accommodates the drive IC 20 is formed before being sealed with the sealing material. Therefore, the sealing material does not adhere to a portion other than the predetermined location, and the bonding failure of the holding substrate 15 does not occur. Therefore, the joint portion of the holding substrate 15 can be provided in the vicinity of the connection portion between the drive IC 20 and the connection electrode 30. Thereby, the clearance gap between the side wall 24a of the accommodating part 24 and drive IC20 can be narrowed, and size reduction of a droplet discharge head can be achieved.

  When the drive IC 20 is connected to the connection electrode 30 of the piezoelectric element 14, as shown in FIG. 17C, a sealing material 17 made of a thermosetting resin is injected from the opening of the housing portion 24, and is 100 ° C. or higher. In this environment, the sealing material 17 is thermally cured to seal the connection portion. Originally, only the connecting portion between the drive IC 20 and the connection electrode 30 may be sealed with the sealing material 17, but the droplet discharge head 10 ′ under development is downsized. Therefore, the gap between the drive IC 20 and the side wall 24a of the housing portion 24 is narrowed. For this reason, the needle for applying the sealing material 17 cannot be inserted into the gap between the drive IC 20 and the side wall 24 a of the housing portion 24. Therefore, the sealing material 17 cannot be applied only to the connection portion between the drive IC 20 and the connection electrode 30. Therefore, the sealing material 17 is injected from the opening of the housing portion 24 and the sealing material 17 is filled in the gap between the drive IC 20 and the side wall 24 a of the housing portion 24, thereby connecting the connection portion between the driving IC 20 and the connection electrode 30. It is sealed.

  Thereafter, as shown in FIG. 17D, after the individual liquid chamber 2 and the like are formed on the individual liquid chamber substrate 12, the nozzle plate 11 is fixed to the individual liquid chamber substrate 12, and the liquid droplet ejection head 10 ′ under development is It is formed.

  However, the droplet discharge head 10 ′ under development has a new problem that the droplet discharge head is warped.

  The present invention has been made in view of the above problems, and an object thereof is to provide a droplet discharge head and an image forming apparatus capable of suppressing warpage.

  In order to achieve the above object, the invention of claim 1 includes: a drive control unit that drives and controls a boosting unit that boosts the pressure in the liquid chamber and discharges the liquid in the liquid chamber from the nozzle; and the drive control unit houses the drive control unit. In the liquid droplet ejection head, comprising: a member having a storage wall of the storage portion; and a sealing material that seals a connection portion between the boosting unit and the control drive unit; And having a sealing force absorbing portion that absorbs the contracting force of the sealing material generated during manufacturing and suppresses the warp of the droplet discharge head. It is what.

  As a result of earnest research on the cause of warping of the droplet discharge head 10 ′ under development, the present applicant has found the following. That is, in order to cure the sealing material 17 made of a thermosetting resin filled in the gap between the drive IC 20 as the drive control unit and the side wall 24a of the housing unit 24, the manufacturing process shown in FIG. It is necessary to hold the droplet discharge head in an environment of 100 ° C. or higher for a predetermined time. At this time, the sealing material 17, the holding substrate 15, the individual liquid chamber substrate 12, and the like are thermally expanded, but the thermal expansion coefficient of the sealing material 17 is larger than the thermal expansion coefficient of the holding substrate 15. For this reason, when the droplet discharge head in the middle of manufacture shown in FIG. 17C is returned to room temperature, the shrinkage amount of the sealing material 17 becomes larger than the shrinkage amount of the holding substrate 15. As a result, a force is applied so that the sealing material 17 fixed to the side wall 24a of the housing portion 24 pulls the side wall 24a of the housing portion 24 toward the driving IC 20 side. As a result, as shown by an arrow Z in FIG. 17C, a contraction stress is applied to the entire holding substrate 15 that is a substrate on which the side wall of the housing portion is formed, so that the holding substrate 15 contracts to the center in FIG.

  In the stage shown in FIG. 17C, the individual liquid chamber substrate 12 is not formed with the individual liquid chamber substrate 12, and the rigidity of the individual liquid chamber substrate 12 is high. There is almost no warpage. However, as shown in FIG. 17D, when the individual liquid chamber 2 or the like is formed and the rigidity of the individual liquid chamber substrate 12 decreases, the holding substrate 15 contracts toward the center in the figure due to the contraction stress. End up. As a result, as shown by an arrow Y in FIG. 17D, both ends of the droplet discharge head in the drawing move upward in the drawing, and the central portion of the nozzle plate 11 in the drawing protrudes downward in the drawing. I found out that I was warping.

  Therefore, in the present invention, a contraction force absorbing portion that absorbs the contraction force of the sealing material at the time of manufacturing is provided, and the contraction force absorbing portion absorbs the contraction force of the sealing material at the time of manufacturing, thereby discharging droplets. Suppresses warping of the head.

  According to the present invention, it is possible to suppress the warp of the droplet discharge head due to the shrinkage force of the sealing material.

The top view which shows the separate liquid chamber board | substrate of the droplet discharge head which concerns on this embodiment. The top view of the holding substrate of the droplet discharge head. AA sectional drawing of FIG. 4A and 4B are diagrams illustrating a manufacturing process of a droplet discharge head according to the present embodiment. The figure explaining the continuation of the manufacturing process. FIG. 9 is a plan view showing a holding substrate of a droplet discharge head according to Modification 1 (A) is a top view which shows the holding substrate of the droplet discharge head of the modification 2, (b) is sectional drawing of the droplet discharge head of the modification 2. FIG. FIG. 9 is a plan view showing a holding substrate of a droplet discharge head according to Modification 3; The top view which shows the holding substrate of the aspect which arranged the absorption groove | channel 2 rows. The top view which shows the holding | maintenance board | substrate of the aspect which provided the contraction force absorption member in the side wall. Schematic explaining the whole structure of the mechanism part of a serial type inkjet recording device. Plan view of the main part of the mechanism Schematic explaining the whole structure of the mechanism part of a line type inkjet recording device. Sectional drawing of the conventional droplet discharge head. The figure explaining the manufacturing process of the conventional droplet discharge head. The figure explaining the manufacturing process of the droplet discharge head under development. The figure explaining the continuation of the manufacturing process of the droplet discharge head under development.

Hereinafter, the present invention will be described in detail based on embodiments.
1 is a plan view showing an individual liquid chamber substrate of the droplet discharge head 10, FIG. 2 is a plan view of a holding substrate, FIG. 3 is a cross-sectional view of the droplet discharge head, and FIG. It is AA 'sectional drawing.
As shown in FIG. 3, the droplet discharge head 10 of this embodiment has a structure in which a nozzle plate 11, an individual liquid chamber substrate 12 on which a plurality of individual liquid chambers 2 are formed, a holding substrate 15 and the like are laminated. ing.

  As shown in FIG. 3, the nozzle plate 11 is a substrate in which a plurality of nozzle arrays 11 each having a plurality of nozzles 11a for discharging ink are arranged, and any material can be selected from the required rigidity and workability. Can be used. In the present embodiment, the number of nozzles in the nozzle row is 300. In addition, the droplet discharge head 10 of the present embodiment has two nozzle rows, but may be four rows, eight rows, or the like.

  Examples of the material for the nozzle plate 11 include metals such as SUS and nickel, alloys such as silicon and ceramics, and resin materials such as polyimide. The processing method of the nozzle 11a can be selected arbitrarily from the characteristics of the material and the required accuracy and workability, and examples include electroforming plating method, etching method, press processing method, laser processing method, photolithography method, etc. it can. The opening diameter, the number of arrays, and the array density of the nozzles 11a can be set to an optimum combination according to the specifications required for the droplet discharge head 10.

  On the individual liquid chamber substrate 12, a plurality of individual liquid chambers 2, fluid resistance portions 3, and common liquid chambers 4 corresponding to the respective nozzles 11a are formed. In addition, a vibration plate 13 is provided on the individual liquid chamber substrate 12, and a lower electrode 14a, a piezoelectric body 14b, and an upper electrode 14c are stacked at a position facing the individual liquid chamber 2 with the vibration plate 13 interposed therebetween. A piezoelectric element 14 is provided as boosting means.

  While the method of boosting the individual liquid chamber 2 using the piezoelectric element 14 can cope with inks having a wide range of physical properties, it has been difficult to increase the density of the liquid chamber array and to reduce the size of the head. However, a technique for increasing the density by using a so-called MEMS process has been established. That is, a semiconductor device manufacturing process (photolithography) is performed by forming a unimorph type actuator in which the diaphragm 13, the lower electrode 14a, the piezoelectric body 14b, the upper electrode 14c, and the like are laminated on the individual liquid chamber substrate 12 using a thin film forming technique. It is possible to increase the density by patterning individual piezoelectric elements 14 and wirings corresponding to the individual liquid chambers.

  Any substrate material for the individual liquid chamber substrate 12 can be used in view of processability and physical properties. Each individual liquid chamber 2 is partitioned by a partition wall. The height of each individual liquid chamber 2 can be arbitrarily set from the head characteristics, but is preferably in the range of 20 to 100 μm. The partition walls between the individual liquid chambers can be arbitrarily set according to the arrangement density, but the partition wall width is preferably 10 to 30 μm. Further, when the partition wall width is narrow, when the piezoelectric element 14 corresponding to a specific individual liquid chamber 2 is driven, mutual interference occurs between the individual liquid chambers adjacent to the individual liquid chamber 2, and the discharge variation increases. . When the partition wall width is narrowed, it can be dealt with by reducing the liquid chamber height.

  Further, when the droplet discharge head 10 is configured so as to have a function of forming an image of 300 dpi or more, the pitch of the individual liquid chambers 2 needs to be 85 μm or less. Thus, in the case where the individual liquid chambers 2 are formed at a narrow pitch interval, it is preferable to use a silicon substrate that can be used for photolithography. Although processing of each individual liquid chamber 2 can be performed arbitrarily, when using the above-described photolithography method, either a wet etching method or a dry etching method can be used. In any method, the diaphragm 103 can be used as an etch stop layer by making the liquid chamber side of the diaphragm 13 provided on the individual liquid chamber substrate 12 into a silicon dioxide film or the like, so that the height of the liquid chamber can be controlled with high accuracy. can do.

  A diaphragm 13 is provided on the individual liquid chamber substrate 12. The vibration plate 13 provided on the individual liquid chamber substrate 12 constitutes an upper wall portion of each individual liquid chamber 2 and is vibrated by a piezoelectric element 14 described later, whereby pressure is applied to the ink in the individual liquid chamber 2. And a droplet is discharged from the nozzle 11a.

Although any diaphragm 13 can be used, it is preferable to use a material having high rigidity such as silicon, nitride, oxide, or carbide. Alternatively, a stacked structure of these materials may be used. In the case where the diaphragm 13 is a laminated film, it is preferable that the internal stress of each material is taken into account and the residual stress is small. For example, the vibration plate 13, when the stack of _Si 3 _{N 4} and SiO ₂ is a SiO ₂ serving as the _Si 3 _{N 4} as the tensile stress and compressive stress are alternately laminated, mentioned above as an example of the stress relaxation It is done.

  The thickness of the diaphragm 13 can be selected according to desired characteristics, but is generally preferably in the range of 0.5 μm to 10 μm, and more preferably in the range of 1.0 to 5.0 μm. If the diaphragm 13 is too thin, the diaphragm 13 is likely to be damaged due to cracks or the like, and if it is too thick, the amount of displacement becomes small and the discharge efficiency decreases. Moreover, when too thin, the natural frequency of the diaphragm 13 will fall, and the drive frequency cannot be raised.

  A piezoelectric element 14 as a boosting unit in which a lower electrode 14a, a piezoelectric body 14b, and an upper electrode 14c are stacked is provided at a position facing the individual liquid chamber 2 with the diaphragm 13 interposed therebetween.

  The lower electrode 14a and the upper electrode 14c of the piezoelectric element 14 can be made of any conductive material. Examples include metals, alloys and conductive compounds. A single layer film or a laminated film of these materials may be used. Further, as a material for the lower electrode 14a and the upper electrode 14c, it is necessary to select a material that does not react with or diffuse to the piezoelectric body 14b sandwiched between these electrodes. For this reason, it is necessary to select a highly stable material. Further, if necessary, the adhesiveness between the piezoelectric body 14b and the diaphragm 13 is taken into consideration, between the lower electrode 14a and the diaphragm 13, between the lower electrode 14a and the piezoelectric body 14b, and between the upper electrode 14c and the piezoelectric body 14b. An adhesion layer may be formed between the two. As specific examples of the lower electrode 14a and the upper electrode 14c, Pt, Ir, Ir oxide, Pd, Pd oxide, and the like can be given as highly stable materials. Examples of the adhesion layer include Ti, Ta, W, and Cr.

  As the material of the piezoelectric body 14b, a ferroelectric material exhibiting piezoelectricity can be used. As examples, lead zirconate titanate and barium titanate are generally used. Arbitrary methods can be used as the film formation method of the piezoelectric body 14b, and examples thereof include a sputtering method and a sol-gel method. The sol-gel method is preferable because the film formation temperature is low.

  The piezoelectric element 14 composed of the piezoelectric body 14b and the electrodes 14a and 14c needs to be formed above the individual liquid chamber 2 with the diaphragm 13 interposed therebetween. When the piezoelectric element 14 is formed on the partition wall that divides the individual liquid chamber 2, the deformation of the diaphragm 13 is hindered, which causes a decrease in discharge efficiency or damage of the piezoelectric element due to stress concentration. The piezoelectric element 14 is formed on the individual liquid chamber 2 with the vibration plate 13 interposed therebetween by patterning using a photolithography method or the like. In addition, when the piezoelectric body 14b is formed by the sol-gel method, a spin coating method or a printing method can also be used. Further, the lower electrode 14 a constituting the piezoelectric element 14 may be common to the individual liquid chambers 2. In this case, the upper electrode 14 c and the piezoelectric body 14 b are patterned for each individual liquid chamber 2.

  The individual liquid chamber substrate 12 is formed with a fluid resistance portion 3 having a narrow flow path that communicates the common liquid chamber 4 and the individual liquid chamber 2. In the present embodiment, the fluid resistance unit 3 is a narrow channel in the direction orthogonal to the paper surface of FIG. The fluid resistance unit 3 has a function of supplying ink from the common liquid chamber 4 to the individual liquid chamber 2, and at the same time, by driving the piezoelectric element 14, the pressure generated in the individual liquid chamber 2 prevents backflow of ink. Is discharged from the nozzle 11a. Therefore, it is necessary to reduce the cross-sectional area of the individual liquid chamber 2 in the ink flow direction and increase the fluid resistance. When silicon is used for the individual liquid chamber substrate 12 and the individual liquid chamber 2 and the fluid resistance portion 3 are formed by photolithography (+ etching), there is an advantage that the individual liquid chamber 2 can be processed under the same conditions.

  The vertical height of the fluid resistance unit 3 in FIG. 3 is preferably the same as that of the individual liquid chamber 2. This is because the fluid resistance can be increased by making the height of the fluid resistance portion 3 from the nozzle plate 11 shorter than that of the individual liquid chamber substrate 12, but in this case, the overetching amount of the individual liquid chamber 2 is reduced. It is necessary to control by time management. For this reason, the height of each fluid resistance part 3 cannot be made uniform due to variations in the etching rate, and the discharge uniformity may be deteriorated.

  On the other hand, by forming the fluid resistance portion up to the diaphragm 13 and making the height of the fluid resistance portion 3 the same as the height of the individual liquid chamber 2, the height of each fluid resistance portion 3 can be made uniform. Ink droplet ejection uniformity can be easily ensured.

  In order to input drive signals to the piezoelectric elements 14 arranged so as to correspond to the individual liquid chambers 2, as shown in FIG. 1, individual wires 14d are drawn from the upper electrodes 14c, respectively. Each individual wiring 14d is drawn out to a substantially central portion in a direction orthogonal to the nozzle arrangement direction of the substrate, and an individual wiring pad 30 is provided at the end.

  Further, a common wiring is drawn out from the lower electrode 14a of each piezoelectric element 14, and the common wiring 14e is near one end of the individual liquid chamber substrate 12 in the nozzle arrangement direction (see FIG. 1A). From the vicinity of the lower end in the drawing), the wiring is drawn to a common wiring pad (not shown) provided near the center.

  The individual wires 14d and the common wires are formed on the first insulating film 41a formed on the diaphragm 13, and the individual wires 14d and the common wires are covered with the second insulating film 41c. .

The individual wiring 14d and the common wiring 14e are preferably formed by the same material and the same process. As the wiring material, a metal / alloy / conductive material having a low resistance value can be used. Further, as the wiring material, it is necessary to use a material having a low contact resistance with the upper electrode 14c and the lower electrode 14a. Examples include Al, Au, Ag, Pd, Ir, W, Ti, Ta, Cu, Cr, and the like, and a stacked structure of these materials may be used in order to reduce contact resistance. As a material for reducing the contact resistance, any conductive compound may be used. Examples include oxides such as Ta ₂ O ₅ , TiO ₂ , TiN, ZnO, In ₂ O ₃ and SnO, nitrides, and composite compounds thereof. The film thickness can be arbitrarily set, but is preferably 3 μm or less. In addition, it is preferable to employ a film forming method with high film thickness uniformity such as a vacuum film forming method.

  Further, since the individual wiring 14d and the common wiring 14e also serve as a joint surface with a holding substrate 15 described later (see FIG. 3), it is necessary to adopt a film thickness / film forming method that can ensure height uniformity. Further, as shown in FIG. 3, the metal layer 41b and the second insulating film 41c made of the same material as the first insulating film 41a, the individual wiring 14d, and the common wiring 14e are also arranged around the ink supply port 5. Since the openings of the holding substrate 15 and the individual liquid chamber substrate 12 are joined in the vicinity of the ink supply port, sealing properties are required. For this reason, in order to improve the height uniformity of the individual wiring 14d and the common wiring 14e with the bonding surface of the holding substrate 15, the periphery of the supply port has the same configuration as the bonding surface of the individual wiring 14d and the common wiring 14e with the holding substrate 15. And improving the reliability of bonding.

  Further, bumps for connecting the driving IC 20 are formed on the individual wiring pads 30 and the common wiring pads (not shown). Examples of the bump forming method include an electrolytic plating method, an electroless plating method, and a stud bump method. Examples of the bump material include Au, Ag, Cu, Ni, and solder.

  A drive IC 20 for generating pressure fluctuations in each piezoelectric element 14 is connected to the individual wiring pad 30 and a common wiring pad (not shown). As a method of connecting the driving IC 20 to the wiring pad, for example, ACF (Anisotropic Conductive Film) bonding using FPC (Flexible Printed Circuits), solder bonding, wire bonding method, flip chip method of directly bonding to the output terminal of the driving IC 20 Etc. can be selected. However, when FPC is used, FPC parts costs are incurred, so the wire bonding method and the flip chip method are preferable because of low cost. In addition, the wire bonding method has a slower tact than the flip chip method, and therefore, the productivity is poor, and a narrow pitch is disadvantageous. For this reason, in this embodiment, the drive 1C20 is directly bonded to the wiring pad using the flip chip method.

  The drive IC 20 as the drive control unit is formed by a wafer process, and bumps are also formed on the wiring pads of the drive IC 20. Thereafter, the drive IC 20 is formed by dividing each chip by dicing or the like.

Since the individual liquid chamber substrate 12 is as thin as 20 to 100 μm, the holding substrate 15 is joined to make the individual liquid chamber substrate 12 difficult to deform in order to ensure the rigidity of the individual liquid chamber substrate 12. Therefore, the holding substrate 15 is preferably not a low-rigidity material such as resin but a high-rigidity material such as silicon. In addition, in order to prevent the individual liquid chamber substrate 12 from warping, it is necessary to select a material having a close thermal expansion coefficient. Therefore, it is preferable to use ceramic materials such as glass, silicon, SiO ₂ , ZrO ₂ , and Al ₂ O ₃ .

  A plurality of recesses 16 for securing a space in which the piezoelectric element 14 can be driven and the diaphragm 13 can be displaced is formed in a region facing the piezoelectric element 14 of the holding substrate 15. Each concave portion of the holding substrate is partitioned for each individual liquid chamber 2 and joined on the individual liquid chamber partition walls. Thereby, the rigidity of the individual liquid chamber substrate 12 having a small plate thickness can be increased, and mutual interference between adjacent liquid chambers when the piezoelectric element 14 is driven can be reduced. Further, since the concave portion 16 of the holding substrate 15 is partitioned for each individual liquid chamber 2, high processing accuracy is required for high density, and the partition width for partitioning the concave portion 16 of the holding substrate 15 in the 300 dpi head. Is preferably 5 to 20 μm.

  In addition, as shown in FIG. 2, the holding substrate 15 is formed with a housing portion 24 for housing the drive IC 20. If an external force such as bending or impact is applied to the connection portion between the driving IC 20 and the wiring pad, the connection between the driving IC 20 and the wiring pad may be disconnected. Further, the connection between the drive IC 20 and the wiring pad may be disconnected due to thermal stress. In addition, due to temperature and humidity changes, moisture may adhere to the connection portion between the drive IC 20 and the wiring pad, and this connection portion may be corroded. From the viewpoint of preventing these problems, in the present embodiment, as shown in FIG. 3, the accommodating portion 24 is filled with the sealing material 17 to underfill the connecting portion between the drive IC 20 and the wiring pad.

  The sealing material 17 uses a thermosetting resin, and after the liquid thermosetting resin is poured into the gap between the drive IC 20 of the housing portion 24 and the side wall 24a of the housing portion, the thermosetting resin is heated by 100 ° or more. To cure. However, since the shrinkage rate of the sealing material 17 is higher than that of the holding substrate 15 when the temperature is returned to room temperature after that, the holding substrate 15 is shrunk by the shrinkage force of the sealing material 17 and the droplet discharge head 10 is bent. In FIG. 3, there is a case in which a warp such that the central portion of the droplet discharge head 10 is convex downward in the drawing may occur.

  For this reason, in this embodiment, as shown in FIGS. 2 and 3, the absorption hole 18 is provided around the accommodating portion 24 of the holding substrate 15, and the holding substrate 15 has a contracting force due to contraction of the sealing material 17. When added, only the periphery of the accommodating portion 24 of the holding substrate 15 is deformed to absorb the contraction force, and warpage due to the contraction force can be suppressed. By providing the absorption hole 18 around the accommodating portion 24 of the holding substrate 15, the periphery of the side wall 24a of the accommodating portion 24 (hereinafter referred to as the side wall portion 24c) can be elastically deformed. Thereby, when the sealing material 17 tries to contract, the side wall part 24c of the accommodating part 24 as a contraction force absorption part elastically deforms and moves to the drive IC 20 side, thereby absorbing the contraction stress. Thereby, it is possible to suppress the entire holding substrate 15 from being contracted by the contracting force of the sealing material 17, and it is possible to suppress warping of the droplet discharge head 10.

  The absorption hole portion 18 is formed in the vicinity of the accommodating portion 24. For example, the absorption hole 18 is formed at a distance from the side wall 24a by the thickness of the holding substrate 15, that is, about 600 μm.

Next, manufacture of the droplet discharge head 10 of this embodiment will be described.
4 and 5 are diagrams for explaining a manufacturing process of the droplet discharge head 10.
First, as shown in FIG. 4A, the manufacture of a substrate composed of the individual liquid chamber substrate 12, the piezoelectric element 14 and the like to which the holding substrate 15 is bonded will be described.

A diaphragm 13 having a three-layer structure of 0.6 μm SiO ₂ layer, 1.5 μm Si layer, and 0.4 μm SiO ₂ layer is formed on a silicon wafer as an individual liquid chamber substrate 12 having a diameter of 6 inches and a thickness of 600 μm. After that, a lower electrode layer composed of a 20 nm Ti layer and a 200 nm Pt layer is formed by sputtering. Next, a film of 2 μm in thickness was formed on the lower electrode layer by a sol-gel method using lead zirconate titanate (PZT) as an organometallic solution, and then fired at 700 ° C. to form a PZT piezoelectric film. Thereafter, a Pt layer having a thickness of 200 nm is formed on the piezoelectric film by a sputtering method to form an upper electrode layer.

  After the formation of the upper electrode layer, the upper electrode layer, the piezoelectric film, and the lower electrode layer are patterned by a dry etching method, thereby forming the piezoelectric elements 14 corresponding to the individual liquid chambers 2 arranged as shown in FIG. The arrangement pitch of the piezoelectric elements 14 was 85 μm, and the width of the piezoelectric body 14b was 40 μm. The length of the piezoelectric element 14 in the longitudinal direction (FIG. 1 (c) left-right direction) was set to 1000 μm. The number of arrangement of the piezoelectric elements 14 was 300. Further, the droplet discharge heads 10 of the present embodiment are arranged in two rows, but may be four rows, eight rows, or the like.

  Next, a first insulating film 41a is formed by plasma CVD, and individual wiring contact holes and common wiring contact holes are formed in the first insulating film 41a on the upper electrode 14c. Next, a metal layer was formed by sequentially laminating a 50 nm Ti layer and a 2 μm Al layer and performing dry etching, thereby forming an individual wiring 14 d and a common wiring 14 e and a metal layer 41 b around the ink supply port. The width of the common wiring 14e was 300 μm. Then, the second insulating film 41c is formed on the metal layer 41b, the individual wiring 14d, and the common wiring 14e by plasma CVD.

  Next, the portion of the diaphragm 13 that becomes the ink supply port 5 is removed by dry etching. Then, stud bumps made of Au are formed on the electrode pads 30 which are the ends of the individual wirings 14d and the common wirings 14e drawn out from the piezoelectric elements 14, and the holding substrate 15 as shown in FIG. A substrate to be bonded is formed.

  Next, the holding substrate 15 in which the accommodating portion 24, the ink supply port 5, the absorption hole portion 18, and the concave portion 16 shown in FIGS. 2 and 3 are formed is formed using a φ6 inch silicon wafer.

  First, the wafer is polished to a thickness of 400 μm, and an oxide film or the like is formed on the holding substrate 15 on the individual liquid chamber substrate 12 side. Next, the oxide film at the portions that become the concave portion 16, the accommodating portion 24, the ink supply port 5, and the absorption hole portion 18 is removed by photolithography patterning. Next, a resist is formed on the patterned oxide film, and through holes that pass through the holding substrate 15 such as the storage portion 24, the slit-shaped absorption hole portion 18 parallel to the storage portion 24, and the ink supply port 5 are formed. Photoresist patterning is performed on the resist. Then, the accommodating portion 24, the absorption hole portion 18, and the ink supply port 5 are formed through the ICP etching from the individual liquid chamber substrate side.

  Next, only the resist on the individual liquid chamber substrate side of the holding substrate 15 is removed, and the concave portion 16 is formed by half-etching the substrate side by ICP etching using the first patterned oxide film pattern as a mask. Finally, by removing the oxide film, it is possible to form the holding substrate 15 in which the accommodating portion 24, the ink supply port 5, the absorption hole portion 18, and the concave portion 16 are formed.

  An epoxy adhesive is applied to the bonding surface of the holding substrate 15 formed as described above with a flexo printing machine at a film thickness of 2 μm and bonded, and the adhesive is cured to bond the holding substrate 15 to the individual liquid chamber substrate 12. (See FIG. 4B).

  After the holding substrate 15 is bonded, the driving IC 20 is bonded. Au stud bumps are formed on the electrodes of the driving IC 20, and are bonded onto the stud bumps of the wiring pads 30 on the individual liquid chamber substrate 12. An ultrasonic method was used as a bonding method. Thereafter, the liquid sealing material 17 is injected into the gap between the driving IC 20 and the side wall 24a of the housing portion 24 using a needle (see FIG. 5C). As the sealing material 17, a thermosetting epoxy resin was used. By using an epoxy resin as the sealing material 17, the epoxy resin can obtain high water resistance and can maintain high insulation properties for a long time. In the present embodiment, it is preferable to use a thermosetting resin as the sealing material 17 so that the sealing material 17 can be reliably cured. This is because, for example, when a resin curable by light energy such as an ultraviolet curable resin is used as the sealing material, it is not possible to irradiate the connection portion between the driving IC 20 and the wiring pad 30 with the sealing material 17. Cannot be cured. On the other hand, when a thermosetting resin is used, thermal energy can be reliably applied to the connection portion between the drive IC 20 and the wiring pad 30, and the sealing material 17 can be reliably cured.

  After injecting the epoxy resin sealing material 17 into the gap between the driving IC 20 and the side wall 24a of the housing portion 24, the epoxy resin sealing material 17 is held at 100 ° C. or higher for 1 hour or longer to cure the thermosetting resin and return to room temperature.

  In the present embodiment, after the holding substrate 15 is bonded, the driving IC 20 is bonded and the connecting portion between the driving IC 20 and the wiring pad is sealed with the sealing material 17. As described above, the holding substrate 15 is bonded onto the second insulating film 41c on the individual liquid chamber substrate 12 before the connection portion is sealed with the sealing material 17, so that the holding substrate 15 of the second insulating film 41c is bonded. The sealing material 17 does not adhere to the joint surface. Thereby, the holding substrate 15 can be favorably bonded onto the second insulating film 41c.

  Further, since the sealing material 17 is for preventing the connection between the driving IC 20 and the wiring pad 30 from being disconnected or corroded as described above, the sealing material 17 is connected to the driving IC 20. It is sufficient to apply only to the connection portion with the wiring pad 30. However, in this embodiment, as described above, when the holding substrate 15 is bonded and then the sealing material 17 is applied, the needle is applied only to the connection portion between the drive IC 20 and the wiring pad 30. Needs to be inserted into the gap between the drive IC 20 and the side wall 24 a of the housing portion 24. In this case, if the gap between the drive IC 20 and the side wall 24a of the accommodating portion 24 is increased so that the needle enters, the droplet discharge head 10 is increased in size. Therefore, in the present embodiment, the gap between the drive IC 20 and the side wall 24a of the housing portion 24 is set to a space where the needle cannot be inserted, and the sealing material 17 is opened from the opening side (the side opposite to the substrate side) of the housing portion 24. Injecting. For this reason, in the present embodiment, the sealing material 17 is also sealed in the gap between the side wall 24a of the housing portion 24 and the drive IC 20.

  As described above, in order to cure the sealing material 17 made of thermosetting resin, in the present embodiment, the droplet discharge head in the middle of manufacture shown in FIG. Hold. Therefore, each member constituting the droplet discharge head 10 is thermally expanded. When the temperature is returned to room temperature from the high temperature environment as described above, each thermally expanded member contracts. Since the thermal expansion coefficient of the sealing material 17 is higher than the thermal expansion coefficient of the holding substrate 15, the sealing material 17 contracts more than the holding substrate 15 when the temperature is returned to room temperature. Therefore, the sealing material 17 fixed to the side wall 24a of the housing portion 24 is applied with a contraction stress that moves the side wall 24a of the housing portion 24 toward the drive IC 20 side. In the present embodiment, as shown in FIG. 2, the slit-shaped absorption hole 18 is provided around the housing portion 24, and only the side wall portion 24c (around the side wall 24a) of the housing portion 24 is elastically deformed. It is configured as follows. Therefore, when a contraction stress that pulls the side wall 24a to the drive IC side due to the contraction of the sealing material 17 is applied, the side wall portion 24c as the contraction force absorbing portion is elastically deformed to absorb the contraction stress. Thereby, the shrinkage stress applied to the holding substrate 15 can be significantly reduced as compared with the case where the absorption hole 18 is not provided.

  When the sealing material 17 is thermally cured, the thickness of the individual liquid chamber substrate 12 is as thick as 600 μm, and the rigidity of the individual liquid chamber substrate 12 is high. Therefore, even if the absorption hole 18 is not provided, the warpage at this point is originally small. However, as will be described below, when the individual liquid chamber substrate 12 is polished to 80 μm and the individual liquid chamber 2 or the like is formed, the rigidity of the individual liquid chamber substrate 12 is greatly reduced. Warpage occurs in the case that is not provided.

  When the sealing material 17 is thermally cured, as shown in FIG. 5D, the 600 μm individual liquid chamber substrate 12 is polished to 80 μm. After polishing, the individual liquid chamber 2, the fluid resistance portion 3, and the common liquid chamber 4 are formed by ICP dry etching. The width of the individual liquid chamber 2 (in the direction orthogonal to the plane of FIG. 5) was 60 μm, the width of the fluid resistance portion 3 was 30 μm, and the length of the individual liquid chamber 2 (left-right direction in FIG. 5) was 300 μm. Etching of the fluid resistance unit 3 and the individual liquid chamber 2 was performed until reaching the vibration plate 13 so as to have the same height. Further, since the ink supply port 5 of the vibration plate 13 has already been removed, if the portion corresponding to the common liquid chamber 4 reaches the vibration plate 13, it becomes a through hole, and the ink supply port 5 and the common liquid chamber 4. Will be in communication.

  Here, when the individual liquid chamber substrate 12 is polished, the thickness of the substrate composed of the individual liquid chamber substrate 12 and the holding substrate 15 is reduced by about half from 1000 μm to 480 μm, and the bending rigidity is reduced to about 1/8. Therefore, in the case where the absorption hole portion 18 is not formed, warping occurs at this point due to the contraction force of the sealing material 17. On the other hand, in the present embodiment, as described above, only the accommodating wall portion 24c is deformed to absorb the contraction force, so that the contraction stress of the holding substrate 15 is remarkably reduced. Even after polishing, almost no warpage occurred.

  When the individual liquid chamber 2 or the like is formed on the individual liquid chamber substrate 12, the wafer is cut into chips by dicing. Next, the nozzle plate 11 and the individual liquid chamber substrate 12 are joined by the same method as the holding substrate 15. As the nozzle plate 11, a SUS material having a thickness of 30 μm formed by press-forming nozzles 11a having a diameter of 20 μm at a pitch of 85 μm was used. Then, a connection substrate for connecting to a SUS ink tank (not shown) is joined on the holding substrate 15 and connected to the ink tank, whereby the droplet discharge head 10 is formed.

  In the present embodiment, as described above, since the warping of the member made up of the holding substrate 15 and the individual liquid chamber substrate 12 is suppressed, the warping occurs when the nozzle plate 11 or a connection substrate (not shown) is joined. It is not necessary to apply a large load to correct this. Therefore, it is possible to easily join the nozzle plate 11 and a connection substrate (not shown). Further, after correcting the warp of the member made up of the holding substrate 15 and the individual liquid chamber substrate 12 and joining the nozzle plate 11 and the connection substrate (not shown), the member made up of the holding substrate 15 and the individual liquid chamber substrate 12 is the original. In order to return to the warped state, it is possible to satisfactorily suppress the disconnection with the nozzle plate 11 or the disconnection with the common liquid chamber substrate (not shown).

  Next, a modification of this embodiment will be described.

[Modification 1]
FIG. 6 is a plan view showing the holding substrate 15 of the droplet discharge head according to the first modification.
As shown in FIG. 6, the holding substrate 15 of Modification 1 has a configuration in which the absorption hole portion 18 is not formed around the lateral side wall 24 a-1 (side wall extending in the left-right direction in the drawing) of the accommodating portion 24. It is what. The side wall 24a-1 in the short direction has a smaller contact area with the sealing material 17 injected into the accommodating portion 24 than the side wall 24a-2 in the longitudinal direction extending in the vertical direction in the drawing. For this reason, when the sealing material 17 contracts, the force with which the lateral side wall 24a-1 is pulled toward the drive IC 20 by the sealing material 17 is weak. For this reason, even if the absorption hole 18 is not provided in the vicinity of the side wall 24a-1 in the short direction, the member composed of the holding substrate 15 and the individual liquid chamber substrate 12 does not warp greatly. For this reason, in the first modification, the absorption hole 18 is not provided in the vicinity of the side wall 24a-1 in the lateral direction.

  In the first modification, the strength of the holding substrate 15 can be increased compared with the case where the absorption hole 18 is not provided in the vicinity of the side wall 24a-1 in the short direction. Moreover, since the absorption hole 18 is formed around the side wall 24a-2 in the longitudinal direction that receives a large contractive force from the sealing material 17, warpage can be suppressed satisfactorily.

[Modification 2]
7A and 7B are schematic configuration diagrams of a droplet discharge head according to Modification 2. FIG. 7A is a plan view showing a holding substrate 15, and FIG. 7B is a cross-sectional view.
In the second modification, the structure for absorbing the contraction force formed around the side wall of the accommodating portion 24 is formed into a groove shape as the absorption groove 181.

  As shown in FIG. 7B, the bottom surface of the absorption groove 181 is provided on the side opposite to the connection portion side (the individual liquid chamber substrate 12 side) between the drive IC 20 and the wiring pad 30. Since the main purpose of the sealing material 17 is to seal the connection portion between the driving IC 20 and the wiring pad, as shown in FIG. 7B, the opening side of the accommodating portion 24 (with the individual liquid chamber substrate 12 and The sealing material 17 is not injected up to the opposite side. For this reason, the shrinkage force from the sealing material 17 is not applied to the side wall 24 a on the opening side (the side opposite to the individual liquid chamber substrate 12) of the housing portion 24. In contrast, the individual liquid chamber substrate 12 side of the accommodating portion 24 is filled with the sealing material 17 in order to securely seal the connection portion between the driving IC 20 and the wiring pad. For this reason, the contraction rate on the individual liquid chamber substrate 12 side of the holding substrate 15 increases accordingly, and the contraction force applied to the side wall 24a on the individual liquid chamber substrate 12 side also increases.

  Therefore, the contraction force of the sealing material 17 can be efficiently absorbed by providing the bottom surface of the absorption groove 181 on the opening side of the housing portion 24 (the side opposite to the individual liquid chamber substrate 12). In addition, the rigidity of the holding substrate 15 can be increased as compared with the configuration in which the absorption hole portion 18 is provided, and the holding substrate 15 can have strength to prevent the holding substrate 15 from being broken in the manufacturing process.

[Modification 3]
FIG. 8 is a plan view showing the holding substrate 15 of the droplet discharge head of Modification 3.
This modification 3 is a modification of the previous modification 2. As shown in FIG. 8, a plurality of slit-shaped absorption grooves 181 are provided in the longitudinal direction (vertical direction in the figure).

As shown in FIG. 8, by dividing the absorption groove 181 into a plurality of parts, the strength of the holding substrate 15 can be increased compared to the configuration shown in FIG. Thereby, compared with the structure shown in FIG. 7, it can suppress that the holding substrate 15 is broken by a manufacturing process. The interval between the absorption grooves 181 is such that the portion between the absorption grooves 181 is not broken by the contraction force of the sealing material 17, and the side wall portion 24 c can be deformed to absorb the contraction force of the sealing material satisfactorily. The interval between the absorption grooves 181 and the length of the absorption grooves 181 in the vertical direction in the figure are set as appropriate. As a specific example, the width b of each absorption groove is 100 μm, the distance d from the side wall 24a to the absorption groove 181 is 200 μm, the length a of each absorption groove is 1000 μm, and the distance c between the absorption grooves is 200 μm. By setting it as such a dimensional relationship, the location between the absorption grooves 181 is not destroyed, but the shrinkage | contraction force of the sealing material 17 can be absorbed favorably.
Moreover, in the structure shown in FIG. 8, although it is set as the absorption groove | channel 181, the structure penetrated as an absorption hole may be sufficient.

  Further, as shown in FIG. 9, the absorption grooves 181 may be arranged in two rows so that the first row and the second row are staggered. By setting it as this structure, the ability to absorb the contractive force of the sealing material 17 can be significantly enhanced while maintaining the strength. As a specific example, the width of each absorption groove 181 is 100 μm, the distance from the side wall 24a of the accommodating portion 24 to the absorption groove 181 is 200 μm, the length of each absorption groove 181 is 1000 μm, and the distance c between the absorption grooves 181 is: 500 μm, distance e between the first and second rows e: 200 μm. Further, there may be two or more rows of the absorption grooves 181 as long as the strength of the holding substrate 15 and the shrinkage stress of the holding substrate are optimized.

  Further, as shown in FIG. 10, a contraction force absorbing member 182 made of an elastic member such as rubber or sponge may be provided on the side wall 24a. With this configuration, the sealing material 17 filled in the accommodating portion 24 is fixed to the contraction force absorbing member 182 so that the sealing material 17 is moved to the contraction force absorbing member 182 toward the driving IC 20 due to contraction. Stress is applied. When a contraction stress that pulls the contraction force absorbing member 182 to the drive IC side due to the contraction of the sealing material 17 is applied, the contraction force absorption member 182 made of an elastic member such as rubber or sponge is elastically deformed to absorb the contraction stress. To do. Thereby, the contraction force applied to the side wall 24a can be reduced, and even if the absorption groove 181 is divided into a plurality of parts to slightly increase the strength and the side wall part 24c is hardly deformed, the remaining contraction force is applied to the side wall part 24c. It can absorb well. Thereby, the ability to absorb the shrinkage force of the sealing material 17 can be significantly enhanced while maintaining the strength.

  The contraction force absorbing member 182 can be formed by dipping or the like on the side wall 24 a of the accommodating portion 24 of the holding substrate 15 by applying a resist on both surfaces of the holding substrate 15.

Next, a configuration example of an ink jet recording apparatus as an example of an image forming apparatus including the droplet discharge head 10 according to the embodiment will be described.
FIG. 11 is a schematic diagram for explaining the overall configuration of the mechanism unit of the ink jet recording apparatus, and FIG. 12 is a plan view of the main part of the mechanism unit.
This ink jet recording apparatus is a serial type ink jet recording apparatus, and a carriage 233 is slidably held in a main scanning direction by a main guide rod 231 and a sub guide rod 232 which are guide members horizontally mounted on left and right side plates 221A and 221B. To do. Then, the main scanning motor (not shown) moves and scans in the direction indicated by the arrow (carriage main scanning direction) in FIG. 2 via the timing belt. The carriage 233 is mounted with a droplet discharge head unit for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). In this droplet discharge head unit, the recording head 234 is arranged in a sub-scanning direction perpendicular to the main scanning direction with a nozzle row composed of a plurality of nozzles, and the ink droplet discharging direction is directed downward. The recording head 234 is configured by attaching droplet discharge heads 234a and 234b each having two nozzle rows to one base member. Then, one nozzle row of one head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and one nozzle row of the other head 234b has magenta (M) droplets. Droplets are discharged, and the other nozzle row discharges yellow (Y) droplets. In this example, a four-color droplet is ejected with a two-head configuration, but a droplet ejection head for each color may be provided. The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 235” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridge 210 of each color by the supply unit 224 via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. Paper roller) 243 and paper feed roller 243. A separation pad 244 made of a material having a large friction coefficient is provided, and the separation pad 244 is urged toward the paper feed roller 243 side. A sheet 242 fed from the sheet feeding unit is fed to the lower side of the recording head 234. For this purpose, a guide member 245 for guiding the paper 242, a counter roller 246, a conveyance guide member 247, and a pressing member 248 having a tip pressure roller 249 are provided. In addition, a transport belt 251 serving as a transport unit for electrostatically attracting the fed paper 242 and transporting the paper 242 at a position facing the recording head 234 is provided. The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction).

  In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown). Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. ing. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272. Further, a maintenance / recovery mechanism 281 for maintaining and recovering the nozzle state of the recording head 234 is disposed in a non-printing area on one side in the scanning direction of the carriage 233. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge thickened ink. Yes.

  In addition, in the non-printing area on the other side of the carriage 233 in the scanning direction, idle ejection that receives droplets when performing idle ejection that ejects droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like. A receptacle 288 is arranged. The idle discharge receiver 288 includes an opening 289 along the nozzle row direction of the recording head 234. In the image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245. Then, the paper is sandwiched between the transport belt 251 and the counter roller 246 and transported. Further, the front end is guided by the transport guide 237 and pressed against the transport belt 251 by the front end pressure roller 249, and the transport direction is changed by approximately 90 °. The At this time, an alternating voltage is applied to the charging roller 256 so that a positive output and a negative output are alternately repeated. In this case, a positive voltage and a negative voltage are alternately charged in a band shape with a predetermined width in a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251. Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203. As described above, since the image forming apparatus includes the droplet discharge head according to the present invention as a recording head, it is possible to perform highly reliable and stable droplet discharge, and to perform high-speed and high-quality images. Can be formed.

  Next, another configuration example of the ink jet recording apparatus as an example of an image forming apparatus including the droplet discharge head 10 according to the embodiment will be described. FIG. 13 is a schematic configuration diagram of another entire mechanism unit of the ink jet recording apparatus. This ink jet recording apparatus is a line type ink jet recording apparatus, and has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided. A sheet 403 fed from the sheet feeding tray 404 is taken in, and a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405. Thereafter, the paper 403 is discharged onto a paper discharge tray 406 attached to the side of the apparatus main body 401. In addition, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided. When performing double-sided printing, after the one-side (front) printing is completed, the paper 403 is taken into the double-sided unit 407 while being conveyed in the reverse direction by the conveyance mechanism 405. Then, the sheet is reversed and sent to the transport mechanism 405 again with the other side (back side) as a printable side, and the paper 403 is discharged to the discharge tray 406 after the other side (back side) printing is completed. Here, the image forming unit 402, for example, ejects droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y), and has four full-line droplet ejection heads 10. The recording heads 411k, 411c, 411m, and 411y (referred to as “recording heads 411” when colors are not distinguished) are provided, and each recording head 411 has a nozzle surface on which nozzles for discharging droplets are directed downward. It is attached to the head holder 413.

  Also, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (hereinafter referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) for maintaining and recovering the performance of the recording head is provided corresponding to each recording head 411. During the head performance maintenance operation such as purge processing and wiping processing, the recording head 411 and the maintenance / recovery mechanism 412 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 412 faces the nozzle surface of the recording head 411. Let Here, the recording head 411 is arranged to eject droplets of each color in the order of blank, cyan, magenta, and yellow from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this.

  Further, as the line-type recording head, one or a plurality of recording heads provided with a plurality of nozzle rows for discharging droplets of each color at predetermined intervals can be used. Further, the recording head and the recording liquid cartridge that supplies ink to the recording head can be integrated or separated. The sheets 403 in the sheet feed tray 404 are separated one by one by a sheet feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401. Then, the sheet is fed between the registration roller 425 and the conveyance belt 433 along the guide surface 423a of the conveyance guide member 423, and is fed to the conveyance belt 433 of the conveyance mechanism 405 via the guide member 426 at a predetermined timing.

  In addition, the conveyance guide member 423 is also formed with a guide surface 423 b for guiding the paper 403 sent out from the duplex unit 407. Further, a guide member 427 for guiding the sheet 403 returned from the transport mechanism 405 to the duplex unit 407 during duplex printing is also provided. The transport mechanism 405 includes a transport belt 433, a charging roller 434, a plantain member 435, and a pressing roller 436. The conveyance belt 433 is an endless conveyance belt that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432. The charging roller 434 is a charging roller for charging the conveyance belt 433. The platen member 435 is a member that maintains the flatness of the transport belt 433 at a portion facing the image forming unit 402. The holding roller 436 presses the sheet 403 fed from the conveying belt 433 against the conveying roller 431 side. Although not shown in the drawings, a cleaning roller made of a porous material or the like, which is a cleaning means for removing ink attached to the conveyance belt 433, is also provided. On the downstream side of the transport mechanism 405, a paper discharge roller 438 and a spur 439 for sending the paper 403 on which an image is recorded to the paper discharge tray 406 are provided.

  In the image forming apparatus configured as described above, the transport belt 433 moves in the direction indicated by the arrow and is charged by coming into contact with the charging roller 434 to which a high potential applied voltage is applied. When the paper 403 is fed onto the conveyance belt 433 charged to this high potential, the paper 403 is electrostatically attracted to the conveyance belt 433. In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface. Then, the sheet 403 is moved around the conveyor belt 433, and droplets are ejected from the recording head 411. As a result, a required image is formed on the sheet 403, and the sheet 403 on which the image is recorded is discharged to the discharge tray 406 by the discharge roller 438.

  Thus, in this ink jet recording apparatus, it is possible to improve the uniformity of droplet discharge by reducing the resistance of the common electrode and suppressing delamination as will be described later. In the above embodiment, the liquid droplet ejection head according to the present invention is applied to the ink jet head. It can also be applied to heads.

  In the above description, the piezoelectric actuator method using the piezoelectric element 14 is employed as the pressure increasing means for increasing the pressure of the individual liquid chamber 2 and ejecting ink droplets from the nozzles. It is possible to use a thermal method in which bubbles are generated in the individual liquid chamber 2 by using the pressure to raise the pressure of the individual liquid chamber and eject ink droplets from the nozzles.

What has been described above is an example, and the present invention has a specific effect for each of the following aspects.
(Aspect 1)
A drive control unit such as a drive IC 20 for driving and controlling a boosting unit such as a piezoelectric element 14 that increases the pressure of the liquid chamber such as the individual liquid chamber 2 and discharges the liquid in the liquid chamber from the nozzle 11a is accommodated in the drive control unit. In the droplet discharge head 10 including a member such as the holding substrate 15 having the accommodating wall 24a of the accommodating portion 24 and the sealing material 17 that seals the connecting portion between the boosting means and the control driving portion, the accommodating wall The side wall portion having the sealing material 17 in the gap between the drive control unit 24a and the warp of the liquid droplet ejection head 10 by absorbing the contraction force of the sealing material 17 generated during manufacturing. It has a contraction force absorbing portion such as 24c.
By providing such a configuration, it is possible to suppress warping of the droplet discharge head as described in the embodiment.

(Aspect 2)
Further, in the droplet discharge head 10 of (Aspect 1), the droplet discharge head 10 is formed after bonding a substrate such as the holding substrate 15 having the accommodating wall 24a to a substrate on which a boosting unit such as the piezoelectric element 14 is formed. The sealing material 17 is manufactured through a process of filling a gap between the housing wall 24a and a drive control unit such as a drive IC.
By providing such a configuration, as described in the embodiment, it is possible to prevent the bonding failure of the substrate having the accommodation wall 24a and to reduce the size of the droplet discharge head 10.

(Aspect 3)
Further, in the liquid droplet ejection head 10 of (Aspect 1) or (Aspect 2), the contraction force absorbing portion is configured to be elastic only around the accommodation wall 24a of a member such as the holding substrate 15 having the accommodation wall 24a. Formed.
By adopting such a configuration, as described in the embodiment, the contraction force of the sealing material can be absorbed by elastically deforming only the periphery of the storage wall 24a, and the warpage of the droplet discharge head 10 can be suppressed. be able to.

(Aspect 4)
Further, in the droplet discharge head 10 of (Aspect 3), by providing a through hole such as the absorption hole 18 around the accommodation wall of a member such as the holding substrate 15 having the accommodation wall 24a, the contraction force of the side wall 24c or the like. An absorption part was formed.
With such a configuration, as described in the embodiment, the periphery of the accommodation wall 24a can be elastically deformed.

(Aspect 5)
Further, in the droplet discharge head 10 of (Aspect 3), a contraction force absorbing portion such as the side wall portion 24c is formed by providing a groove such as the absorption groove 181 around the housing wall of a member such as the holding substrate 15.
Even with this configuration, as described in the second modification, the periphery of the accommodation wall 24a can be elastically deformed. Further, the strength of the substrate having the accommodating wall 24a such as the holding substrate 15 can be increased as compared with the case where the through-hole is formed, and the occurrence of cracking of the substrate can be suppressed.

(Aspect 6)
Further, in the liquid droplet ejection head 10 of (Aspect 5), the bottom surfaces of the grooves such as the absorption grooves 181 are provided on the side opposite to the connection portion side.
By providing such a configuration, the shrinkage force of the sealing material can be satisfactorily absorbed as described in the second modification.

(Aspect 7)
Further, in the droplet discharge head 10 of any one of (Aspect 4) to (Aspect 6), by providing such a configuration in which a plurality of through holes or grooves are arranged around the accommodation wall, as described in Modification 3, Compared with the case where a single long through-hole or groove is provided, the strength of the substrate such as the holding substrate 15 having the accommodation wall 24a can be increased, and the occurrence of cracks in the substrate can be suppressed.

(Aspect 8)
Further, in the droplet discharge head of (Aspect 7), through holes or grooves are staggered around the accommodation wall 24a.
With this configuration, as described with reference to FIG. 9, the strength of the substrate such as the holding substrate 15 having the accommodation wall 24a can be increased, and the periphery of the accommodation wall 24a can be elastically deformed satisfactorily. Can be absorbed well.

(Aspect 9)
Further, in an image forming apparatus equipped with a droplet discharge head for discharging droplets, the droplet discharge head according to any one of (Aspect 1) to (Aspect 8) is used as the droplet discharge head.
By providing such a configuration, a good image can be obtained.

2: individual liquid chamber 3: fluid resistance unit 4: common liquid chamber 5: ink supply port 10: droplet discharge head 11: nozzle plate 11a: nozzle 12: individual liquid chamber substrate 13: vibration plate 14: piezoelectric element 14a: lower part Electrode 14b: Piezoelectric body 14c: Upper electrode 14d: Individual wiring 14e: Common wiring 15: Holding substrate 16: Recess 17: Sealing material 18: Absorption hole 24: Housing 24a: Side wall 24c: Side wall 30: Individual wiring pad (Connection electrode)
41a: first insulating film 41b: metal layer 41c: second insulating film

JP 2006-281648 A

Claims (9)

A drive control unit that drives and controls a boosting unit that boosts the pressure in the liquid chamber and discharges the liquid in the liquid chamber from the nozzle;
A member having a storage wall of a storage unit in which the drive control unit is stored;
In a droplet discharge head provided with a sealing material that seals a connection portion between the boosting unit and the control drive unit,
It is the structure which has the above-mentioned sealing material in the crevice between the above-mentioned storage wall and the above-mentioned drive control part,
A droplet discharge head, comprising: a contraction force absorbing portion that absorbs a contraction force of the sealing material generated during manufacture and suppresses warpage of the droplet discharge head. The droplet discharge head according to claim 1.
The droplet discharge head includes a step of filling the gap between the storage wall and the drive control unit with the sealing material after the member having the storage wall is joined to the member on which the booster is formed. A liquid droplet ejection head manufactured through the process described above. The droplet discharge head according to claim 1 or 2,
A droplet discharge head, wherein the contraction force absorbing portion is formed by a configuration in which only the periphery of the housing wall of the member having the housing wall is elastic. The droplet discharge head according to claim 3.
A droplet discharge head, wherein the contraction force absorbing portion is formed by providing a through hole around the housing wall of the member having the housing wall. The droplet discharge head according to claim 3.
A droplet discharge head, wherein the contraction force absorbing portion is formed by providing a groove around the accommodation wall of the member having the accommodation wall. The droplet discharge head according to claim 5.
A droplet discharge head characterized in that the bottom surface of the groove is provided on the side opposite to the connection portion side. In the droplet discharge head according to any one of claims 4 to 6,
A droplet discharge head, wherein a plurality of the through holes or the grooves are arranged around the storage wall. The droplet discharge head according to claim 7.
A droplet discharge head, wherein the through holes or grooves are arranged in a staggered manner around the accommodation wall. In an image forming apparatus equipped with a droplet discharge head for discharging droplets,
An image forming apparatus using the droplet discharge head according to claim 1 as the droplet discharge head.

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