JP6954174B2 - Liquid discharge head, liquid discharge unit and device that discharges liquid - Google Patents

Description

The present invention relates to a liquid discharge head, a liquid discharge unit, and a device for discharging a liquid.

An image forming apparatus is known that forms an image or the like with liquid ink discharged by a liquid ejection head. Such a device is a kind of "device for discharging liquid" including a liquid discharge unit including a liquid discharge head. The liquid discharge head provided in the device is provided with a plurality of liquid discharge ports (nozzles) in order to realize higher quality image formation and higher speed image formation, and the density of these nozzles is high. It is arranged.

The liquid ejection head includes a nozzle plate and a head component that constitutes an ink supply structure up to an ejection port formed on the nozzle plate. Then, a nozzle cover is attached to protect the nozzle plate and the head constituent member from the collision of the recording medium with the nozzle plate and the head constituent member and the collision of the wiper member for cleaning the nozzle. The nozzle cover has a structure in which the portion corresponding to the nozzle is an opening so that the liquid ink discharged from the nozzle faces the recording medium, and engages with the housing frame of the liquid discharge head. If the gap between this nozzle cover and the surface on which the nozzles are arranged (nozzle surface) is large, the recording medium may enter the gap and cause media clogging (jam) or damage the nozzle. , Etc. occur. Therefore, it is necessary to set the gap between the nozzle cover and the nozzle surface to be less than or equal to the thickness of the recording medium.

In the conventional liquid discharge head, a structure for attaching the nozzle cover with a simple structure is disclosed by providing a protrusion on the outside of the housing frame and providing a hole in the nozzle cover so that the protrusion can be fitted. (See, for example, Patent Document 1).

As in Patent Document 1, when the nozzle cover is fitted to the housing frame, when the nozzle cover is fitted to the housing frame due to the tolerance of the positions and sizes of the protrusions and holes that serve as the fitting portions. The gap between the nozzle surface and the nozzle cover may not always be set to a predetermined value (less than or equal to the thickness of the recording medium). In this case, it is unavoidable that the medium is clogged between the nozzle cover and the nozzle surface, resulting in a jam state.

Further, since the liquid discharge head including the nozzle surface is formed by laminating a head component composed of a frame, an individual liquid chamber substrate, and a nozzle plate with an adhesive, a hole portion (fitting portion) of the frame from the nozzle surface is formed. ) Will increase. In order to achieve the purpose of providing the nozzle cover in consideration of the tolerance, it is necessary to improve the accuracy of the nozzle cover and the head constituent members, or to select and use the parts. Then, there arises a problem that the manufacturing cost of the liquid discharge head including the nozzle cover becomes high. On the other hand, in order to avoid selecting the nozzle cover and the head constituent members, the position (height) of the protrusion on the nozzle cover side may be set to the tolerance range of the hole on the frame side. The gap between the nozzle cover and the nozzle surface will not be less than the thickness of the recording medium. That is, there is a trade-off between setting the gap between the nozzle cover and the nozzle surface to be less than or equal to the thickness of the recording medium and the manufacturing cost of the liquid discharge head.

An object of the present invention is to provide a liquid discharge head capable of relaxing the tolerance between the nozzle surface and the nozzle cover included in the liquid discharge head.

In the present invention for solving the above problems, a head main body having a nozzle surface composed of a plurality of nozzles for ejecting droplets and an opening attached to the head main body and facing the nozzle surface. A liquid discharge head including a nozzle cover, wherein a first engaging portion for engaging the nozzle cover with a frame forming a surface orthogonal to the nozzle surface is formed in the head main body portion. The nozzle cover has flexibility, and a second engaging portion that engages with the first engaging portion is formed, and the first engaging portion and the second engaging portion are engaged with each other. It is characterized in that there are a plurality of positions in the height direction of the surface.

According to the present invention, the tolerance between the nozzle surface and the nozzle cover provided in the liquid discharge head can be relaxed.

The perspective view of the apparatus which discharges a liquid which concerns on one Embodiment of this invention. The cross-sectional view of the liquid discharge head which concerns on this embodiment. (A) enlarged cross-sectional view and (b) enlarged plan view of a part of the region of FIG. A cross-sectional view of the liquid discharge head according to the present embodiment in the lateral direction (a) and a cross-sectional view in the longitudinal direction (b). The figure which shows the characteristic of the nozzle cover which concerns on this embodiment (a) figure which shows the initial state, (b) figure which shows the state at the time of engagement. (A) Short sectional view and (b) Longitudinal sectional view of the liquid discharge head according to another embodiment. (A) Short sectional view and (b) Longitudinal sectional view of the liquid discharge head according to still another embodiment. The perspective view which shows the appearance of the nozzle cover which concerns on this embodiment. The perspective view which shows the appearance of the nozzle cover which concerns on another embodiment. The plan view of the main part which shows an example of the apparatus which discharges a liquid which concerns on this invention. FIG. 5 is an explanatory side view of a main part showing another example of the device for discharging the liquid according to the present invention. The plan view of the main part which shows an example of the liquid discharge unit which concerns on this invention. The front explanatory view which shows another example of the liquid discharge unit which concerns on this invention.

Hereinafter, embodiments of the liquid discharge head, the liquid discharge unit, and the device for discharging the liquid according to the present invention will be described with reference to the drawings. The main feature of the present invention is the structure of the liquid discharge head. That is, the liquid discharge head according to the present invention is characterized by an engaging portion between the frame and the head cover. The gist is that in the engaging part of the frame and the head cover, the engaging part of the frame side, the engaging part of the head cover, or both of these engaging parts are set so that the tolerance of the positional relationship with each other can be absorbed. It is to have multiple structures. For example, in the engaging portion on the frame side, the nozzle cover can be stopped at an arbitrary height because a plurality of protrusions arranged in the height direction are serrated. As a result, while alleviating the tolerance of the head (frame) and the nozzle cover, the gap between the head (frame) and the nozzle cover can be made smaller than the paper thickness, and the cost required for the structure of attaching the nozzle cover to the frame can be reduced at the same time. Can be done. The engaging portion on the nozzle cover side may be a hole or a slit as long as it has a shape that can be engaged with the engaging portion on the frame side, and various shapes can be adopted. According to the liquid discharge head according to the present invention having the above characteristics, the requirement for assembly accuracy between the frame and the nozzle cover is relaxed, and parts selection is not required, so that cost reduction can be achieved.

First, an embodiment of an apparatus for discharging a liquid according to the present invention will be described with reference to FIG. As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment includes a mechanism unit 12 including an inkjet head 100, which is an embodiment of a liquid ejection head, inside the apparatus main body 11. In the mechanical unit 12, an ink cartridge 14 having an inkjet head 100 is mounted on a carriage 13 that can move in the scanning direction indicated by an arrow A in FIG.

Next, the basic configuration of the inkjet head 100 will be described with reference to FIG. FIG. 2 is a cross-sectional view in the longitudinal direction of the inkjet head 100 having a substantially rectangular parallelepiped outer shape. As shown in FIG. 2, the inkjet head 100 includes a nozzle cover 301, a structure 25 in which a plurality of parts are laminated, a common liquid chamber 105, a damper 106, a plate 107, and a buffer in this order from the bottom. A chamber 108, a frame 22, and a supply port 24 are provided. The supply port 24 is an opening for supplying liquid to the common liquid chamber and the individual liquid chamber through the supply component 201. A structure formed of the structure 25, the damper 106, the plate 107, and the frame 22 is used as the head main body.

The nozzle cover 301 is provided with an opening 304 corresponding to the nozzle 102a described later and a square hole which is a cover-side engaging portion 302 that engages with the frame 22.

The frame 22 is a component that constitutes the housing of the inkjet head 100, has a role of holding other components included in the inkjet head 100, and is integrally formed with the common liquid chamber 105. Any material can be used for the frame 22 from the viewpoint of required rigidity and workability. Examples of the material that can be used for the frame 22 include iron such as carbon steel (S45C), alloys such as stainless steel (SUS), inorganic materials such as silicon and ceramics, and resin materials such as epoxy and PPS. can. Those having corrosion resistance and low dust generation are preferable.

As the processing method of the frame 22, etching, press processing, laser processing, photolithography method, injection molding and the like can be used depending on the material. When a resin material such as epoxy or PPS is used, it is preferable to use a resin material containing 30% to 50% of glass fiber in order to prevent dimensional error due to heat shrinkage at the time of joining with other parts. An adhesive relief groove may be provided on the joint surface of the frame 22 with the damper 106 in order to secure the area of the damper 106.

The frame 22 is formed with a frame-side engaging portion 303 with which the nozzle cover 301 engages. The frame-side engaging portion 303 is a portion having a convex shape in which a part of the outer surface of the frame 22 is projected. Details of the frame-side engaging portion 303 will be described later.

An elastic adhesive is used for joining the frame 22 and the holding substrate 104, which will be described later. The elastic adhesive is for absorbing structural vibrations and pressure fluctuations related to the individual liquid chamber substrate 103, the common liquid chamber 105, and the individual liquid chamber 103a. As the elastic adhesive, any material can be selected from silicon-based, urethane-based, and those using biomass resources. The elastic modulus of the elastic adhesive is preferably several tens of MPa or less. Further, a material that can be heat-cured is desirable in order to shorten the curing time.

The damper 106 is a component that forms a part of the common liquid chamber 105. Any material can be used for the damper 106 from the viewpoint of required rigidity and workability. Materials that can be used for the damper 106 include, for example, alloys such as stainless steel (SUS), metal materials such as nickel (Ni), inorganic materials such as silicon and ceramics, epoxy, PPS, thermoplastic elastomers, and thermocurable materials. Examples thereof include resin materials such as elastomers and silicone rubbers.

The damper 106 is preferably thin and has low rigidity. Further, from the viewpoint of air permeability and moisture permeability, metal is preferable to resin. In the case of metal, for example, when it is produced by electroforming, the thickness of the portion adjacent to the common liquid chamber 105 is about 1 μm to 7 μm, and the thickness of the other portion is about 10 μm to 30 μm. This facilitates the handling of the damper 106.

The plate 107 is a component provided for improving the sealability of the frame 22 and the damper 106 by reliably pressurizing the damper 106 in order to improve the damper handleability when joining the damper 106 and the frame 22.

As the material of the plate 107, any material can be used from the viewpoint of required rigidity and workability. For example, carbon steel (S45C) iron, stainless steel (SUS) alloys, silicon, inorganic materials such as ceramics, and resin materials such as epoxy and PPS can be mentioned. As its properties, those having corrosion resistance and low dust generation are preferable. As a processing method for obtaining the plate 107, a processing method can be adopted by etching, press processing, laser processing, photolithography method, injection molding, or the like, depending on the type of the material. Further, when a resin material such as epoxy or PPS is used, a dimensional error due to heat shrinkage may become a problem at the time of joining with other parts, so that a glass fiber containing 30% to 50% is preferable.

The nozzle cover 301 is a member for protecting the components constituting the inkjet head 100, such as the nozzle substrate 102, from collision with the recording medium and collision with the wiper. Any material can be used for the nozzle cover 301 from the viewpoint of required rigidity and workability. Examples of the material that can be used for the nozzle cover 301 include iron such as carbon steel (S45C), alloys such as stainless steel (SUS), inorganic materials such as silicon and ceramics, and resin materials such as epoxy and PPS. .. The material used for the nozzle cover 301 is preferably a material having corrosion resistance and low dust generation. Further, the material used for the nozzle cover 301 is preferably one that exhibits springiness. Therefore, iron such as carbon steel (S45C) and metal such as an alloy such as stainless steel (SUS), which can exhibit the springiness required for adhesion to the housing and nozzle surface of the inkjet head 100, are desirable.

The nozzle cover 301 is preferably treated with a water-repellent film in order to prevent ink accumulation. As the processing method of the nozzle cover 301, etching, press processing, laser processing, photolithography method, injection molding and the like can be adopted depending on the material. For example, in the case of metal press working, it is desirable that the plate thickness is about 0.1 mm to 1.5 mm. An opening 304 that exposes the nozzle surface is formed on the bottom surface of the nozzle cover 301 so that the ink droplets ejected from the nozzle surface face the recording medium. Further, the nozzle cover 301 is formed with a cover-side engaging portion 302 forming a second engaging portion for fitting to the frame 22. The cover-side engaging portion 302 is, for example, a square hole, but may have a slit shape. The details of the cover-side engaging portion 302 will be described later.

FIG. 3A is a longitudinal sectional view of one individual liquid chamber 103a included in the structure 25 shown in FIG. FIG. 3B is a cross-sectional view taken along the line AA of FIG. 3A. In FIG. 3A, the nozzle substrate 102, the individual liquid chamber substrate 103, the diaphragm 111, the piezoelectric element 112, the drive circuit member 113, and the holding substrate 104 are laminated in this order from the bottom.

The nozzle substrate 102 is a substrate in which a plurality of nozzles 102a serving as ejection ports for ejecting liquid ink are arranged. As the material (material) forming the nozzle substrate 102, any material can be used from the viewpoint of required rigidity and workability. Examples of the material that can be used for the nozzle substrate 102 include metals or alloys such as stainless steel (SUS) and nickel (Ni), inorganic materials such as silicon and ceramics, and resin materials such as polyimide. As the processing method for forming the nozzle 102a, any processing method can be selected from the characteristics of the material and the required accuracy and workability. For example, an electroforming plating method, an etching method, a press processing method, a laser processing method, a photolithography method, and the like. The opening diameter, the number of arrangements, and the arrangement density of the nozzles 102a can be optimally combined according to the specifications required for the inkjet head 100.

The individual liquid chamber substrate 103 is a substrate laminated on the upper surface of the nozzle substrate 102. The individual liquid chamber substrate 103 is formed with a plurality of individual liquid chambers 103a, a fluid resistance portion 103b, and a liquid supply port 103c. A plurality of individual liquid chambers 103a are formed corresponding to the nozzles 102a. Each upper wall portion of the individual liquid chamber 103a is formed by a diaphragm 111. A fluid resistance portion 103b is formed on the individual liquid chamber substrate 103. The fluid resistance unit 103b communicates the individual liquid chamber 103a with the liquid supply port 103c, which serves as an inlet for ink to be supplied from the common liquid chamber 105 (see FIG. 2), and the individual liquid chamber 103a. It has a function of supplying ink to the liquid chamber 103a.

Further, the fluid resistance unit 103b prevents the backflow of ink due to the pressure generated in the individual liquid chamber 103a by driving the piezoelectric element 112 so that the ink is discharged only from the nozzle 102a. Therefore, the individual liquid chamber 103a is formed so that the cross-sectional area in the ink flow direction becomes small, and has a structure for preventing backflow of ink by increasing the fluid resistance. When silicon is used for the individual liquid chamber substrate 103 and the individual liquid chamber 103a and the fluid resistance portion 103b are formed by the photolithography method and the etching method, they can be processed under the same conditions as the individual liquid chamber 103a.

The individual liquid chamber 103a is partitioned by a partition wall, and a piezoelectric element 112 corresponding to each is formed. The height of the individual liquid chamber 103a can be arbitrarily set from the head characteristics. In this case, it is preferably in the range of 20 μm to 100 μm. The partition wall of the individual liquid chamber 103a can be arbitrarily set according to the arrangement density. For example, when the image formed by using the inkjet head 100 is 300 dpi (about 85 μm pitch), the partition wall is a partition wall. The width is preferably 10 μm to 30 μm. Further, when the partition wall width is narrow, mutual interference between adjacent liquid chambers may occur when the piezoelectric element 112 of the adjacent individual liquid chambers 103a is driven. When mutual completion occurs, the discharge variation becomes large. When the partition wall width is narrowed, mutual interference can be prevented by lowering the liquid chamber height.

As the individual liquid chamber substrate 103, any material having predetermined processability and physical properties can be used as the material (material) thereof. As a material that can be used for the individual liquid chamber substrate 103, for example, if the image formed by using the inkjet head 100 is 300 dpi (about 85 μm pitch) or more, a photolithography method can be used for silicon. A substrate is preferred. Any method can be used for processing the individual liquid chamber 103a, but when the above-mentioned photolithography method is used, either a wet etching method or a dry etching method can be used. Regardless of which method is used, the etch stop layer can be formed by forming the individual liquid chamber 103a side of the diaphragm 111 with a silicon dioxide film or the like, so that the height of the liquid chamber can be controlled with high accuracy.

The individual liquid chamber 103a has a function of ejecting ink as droplets from the nozzle 102a by applying pressure to the liquid ink. A piezoelectric element 112 is laminated on the upper portion of the diaphragm 111 forming the upper wall portion of the individual liquid chamber 103a. The piezoelectric element 112 is configured by laminating a lower electrode 115, a piezoelectric body, and an upper electrode 114. Any diaphragm 111 can be used, but it is preferable to use a highly rigid material such as silicon, nitride, oxide, or carbide. Further, a laminated structure of these materials may be used. In the case of a laminated film, an example is a configuration in which silicon nitride (Si ₃ N _{4 ), which is a tensile stress, and silicon dioxide (SiO 2} ), which is a compressive stress, are alternately laminated to relieve stress.

Further, any conductive material can be used for the lower electrode 115 and the upper electrode 114. Examples of materials that can be used for these include metals, alloys, and conductive compounds. Either of these materials as a single-layer film or a laminated film can be used for the lower electrode 115 and the upper electrode 114. Further, since it is necessary to select a material that does not react with or diffuse with the piezoelectric element 112, it is necessary to select a material having high stability. Further, if necessary, the adhesion layer may be formed in consideration of the adhesion between the piezoelectric element 112 and the diaphragm 111. Examples of the materials of the lower electrode 115 and the upper electrode 114 include platinum (Pt), iridium (Ir), iridium oxide, palladium (Pd), palladium oxide and the like as highly stable materials. Examples of the adhesion layer with the diaphragm 111 include titanium (Ti), tantalum (Ta), tungsten (W), chromium (Cr) and the like.

As the material of the piezoelectric material used for the piezoelectric element 112, a ferroelectric material exhibiting piezoelectricity can be used. For example, lead zirconate titanate and barium titanate are common. Any method can be used as the method for forming the piezoelectric material. For example, there are a sputtering method and a sol-gel method. Among them, the sol-gel method is preferable because of its low film formation temperature. The upper electrode 114 and the piezoelectric body need to be patterned for each individual liquid chamber 103a. For patterning, a normal photolithography method can be used. Further, when the piezoelectric material is formed by the sol-gel method, a spin coating method or a printing method can also be used. The piezoelectric element 112 needs to be formed on the upper part of the individual liquid chamber 103a.

The wiring for inputting the drive signal to the arranged piezoelectric elements 112 is configured to draw out individual wiring from the upper electrode 114 and draw out the wiring from the lower electrode 115. The upper electrode 114 is connected to the connection pad via individual wiring that is part of the wiring layer. The drive IC for controlling the drive signal is arranged on the circuit board of the drive circuit member 113 and is connected to the connection pad. Therefore, wiring is performed from the drive IC to the upper electrode 114 via the connection pad. It is desirable that the wiring is formed of the same material and in the same process. As the wiring material, a metal, an alloy, or a conductive material having a low resistance value can be used. Further, it is necessary to use a material having a low contact resistance with the upper electrode 114 and the lower electrode 115. For example, aluminum (Al), gold (Au), silver (Ag), palladium (Pd), iridium (Ir), tungsten (W), titanium (Ti), tantalum (Ta), copper (Cu), chromium (Cr). ) And so on.

In addition, in order to reduce the contact resistance, a laminated structure of these materials may be used. Any conductive compound may be used as the material for lowering the contact resistance. For example, tantalum pentoxide (Ta ₂ O ₅ ), titanium oxide (TIO ₂ ), titanium nitride (TiN), zinc oxide (ZnO), indium oxide (III) ( _In2 O ₃ ), tin oxide (II) (S). _{n O)} such oxides, nitrides, and their complex compounds. The film thickness can be set arbitrarily, but is preferably 3 μm or less. Further, it is preferable to adopt a film forming method having high film thickness uniformity such as a vacuum film forming method.

The holding substrate 104 is arranged on the upper surface of the individual liquid chamber substrate 103. A recess 104a is formed in the holding substrate 104 at a position corresponding to the piezoelectric element 112. The recess 104a is formed at a position surrounding the piezoelectric element 112. The holding substrate 104 is formed with a holding substrate opening 116 that communicates the liquid supply port with the frame 22 (see FIG. 2). The recess 104a is for securing a space in which the diaphragm 111 can be displaced by driving the piezoelectric element 112.

Since the thickness of the individual liquid chamber substrate 103 is as thin as 20 μm to 100 μm, the holding substrate 104 is joined to the side facing the nozzle substrate 102 in order to secure the rigidity of the individual liquid chamber substrate 103. Any material can be used as the material of the holding substrate 104, but a material having a coefficient of thermal expansion close to that of the individual liquid chamber substrate 103 is selected in order to prevent warpage. Therefore, it is preferable to use a ceramic material such as glass, silicon, silicon dioxide (SiO ₂ ), zirconia (ZrO ₂ ), and aluminum oxide (Al ₂ O _3). The holding substrate 104 has an opening communicating with each other in the arrangement direction of the individual liquid chambers 103a. This opening becomes a part of the common liquid chamber 105.

The recesses 104a of the holding substrate 104 are preferably formed by partitioning each individual liquid chamber 103a and joined on the partition wall of the individual liquid chamber 103a. By joining the recesses 104a, the rigidity of the individual liquid chamber substrate 103 having a thin plate thickness can be increased. As a result, mutual interference between adjacent liquid chambers when the piezoelectric element 112 is driven can be reduced. For that purpose, the holding substrate 104 is preferably a high-rigidity material such as silicon, not a low-rigidity material such as resin. Further, since the recess 104a of the holding substrate 104 is partitioned for each individual liquid chamber 103a, a high degree of processing accuracy is required for high density. Therefore, in the 300 dpi head, it is desirable that the partition wall width of the holding substrate 104 is 5 to 20 μm.

Next, the engagement structure between the nozzle cover 301 and the frame 22 included in the inkjet head 100 will be described in more detail. 4A and 4B are cross-sectional views of the inkjet head 100 according to the present embodiment, in which FIG. 4A is a cross-sectional view taken along the lateral direction of the frame 22, and FIG. 4B is a cross-sectional view taken along the longitudinal direction of the frame 22. Note that FIG. 4 omits the details of the internal structure of the inkjet head 100 and shows only the contour portion forming the outer shape.

As shown in FIG. 4A, the frame 22 has a frame-side engaging portion 305 forming the first engaging portion formed on the wall surface in the longitudinal direction. The frame-side engaging portion 305 according to the present embodiment is composed of a plurality of convex portions, and the shape thereof is serrated in the height direction of the wall surface. The serrated protrusions are formed at intervals of several μm to several hundred μm.

As shown in FIG. 4B, a plurality of frame-side engaging portions 305 are formed side by side in the height direction in the vicinity of both ends in the longitudinal direction of the frame 22. It is desirable that the length in the longitudinal direction is in the range of 1 mm to several mm. In FIG. 4B, frame-side engaging portions 305 are formed at a total of two locations at each of the longitudinal end portions of the frame 22, but they may also be formed at intermediate positions in the longitudinal direction. In that case, as will be described later, the engaging portion on the nozzle cover side may also be formed so as to match the position of the engaging portion 305 on the frame side.

The nozzle cover 301 is formed with a cover-side engaging portion 302 that constitutes a second engaging portion. The cover-side engaging portion 302 is, for example, a square hole formed so that a protrusion of the frame-side engaging portion 305 is caught. The cover-side engaging portion 302 is formed at a position that matches the forming position of the frame-side engaging portion 305.

The nozzle cover 301 is formed with an opening 304 on a surface facing the nozzle 102a when fitted to the frame 22. The opening 304 exposes the nozzle 102a.

The outer shape of the nozzle cover 301 according to this embodiment is shown in FIG. The nozzle cover 301 is a member integrally formed of a single metal thin plate as a member, and the end portion of the thin plate is in a bent state to form an opening above the nozzle cover 301. ing. Each side surface of the nozzle cover 301 stands substantially vertically from the bottom surface and is bent toward the inside of the nozzle cover 301 on the way to the end forming the opening. The portion above the bent portion and in the predetermined height direction from the bottom surface is bent toward the outside of the nozzle cover 301. As a result, the upper end of each side surface (wall surface) is oriented toward the outside of the nozzle cover 301, and the upper opening is widened. That is, a part of the wall surface of the nozzle cover 301, the portion close to the upper opening has a substantially V-shaped vertical cross-sectional shape, and the substantially V-shaped apex is a portion recessed inside the nozzle cover 301. Equivalent to. As shown in FIG. 9, a second engaging portion is formed in the vicinity of the V-shaped portion.

As described above, the bottom surface of the nozzle cover 301 is formed with an opening 304 facing the nozzle 102a. The nozzle cover 301 is formed with a cover-side engaging portion 302. The cover-side engaging portion 302 is formed as a hole portion of a square hole so that the cross-sectional shape of the frame-side engaging portion 305 can be engaged with the serrated protrusion. The cover-side engaging portions 302 are formed at a plurality of locations on one side surface, for example, at two locations each near the end portion in the longitudinal direction. The cover-side engaging portion 302 is formed on both side surfaces of the nozzle cover 301. The area of the opening portion at the upper part of the nozzle cover 301 is substantially equal to or smaller than the area of the bottom surface of the frame 22. When the nozzle cover 301 is covered so as to be pushed upward from the bottom surface side of the frame 22, the opening dimension is expanded outward along the frame side engaging portion 305. After that, it engages with the frame 22 at a predetermined position.

The change in the state when the nozzle cover 301 is engaged with the frame 22 will be described with reference to FIG. FIG. 5A illustrates an initial state of the nozzle cover 301 before it is fitted to the frame 22. FIG. 5B illustrates a warped state of the nozzle cover 301 when it is fitted to the frame 22. As shown in FIG. 5B, the nozzle cover 301 is a component having elasticity so that the opening dimension of the upper opening portion expands according to the outer peripheral dimension of the frame 22. A part of the side surface of the nozzle cover 301 is V-shaped and is recessed inward from the upper opening portion. Therefore, this recessed portion hits the outer wall of the frame and the upper opening portion of the nozzle cover 301 is outward. Expand by pushing. The nozzle cover 301 is integrally formed as a substantially box body in which the upper surface of the rectangular parallelepiped is open, and the material is a flexible metal. Therefore, when the opening portion on the upper surface is changed so as to be expanded, the opening 304 on the lower surface is in a state of warping upward. There is a nozzle surface of the inkjet head 100 at a position facing the opening 304. Due to the warp of the nozzle cover 301, the nozzle cover 301 and the nozzle surface come into closer contact with each other.

Return to FIG. Each of the protrusions constituting the frame-side engaging portion 305 has an inclined portion in which the amount of protrusion from the bottom to the top increases outward, and a portion protruding outward with a certain length as an apex on the wall surface of the frame 22. It consists of a flat part connected to. Therefore, when the nozzle cover 301 is pushed upward from below, the portion further above the formation position of the cover-side engaging portion 302 faces outward along the diagonally upward surface of the frame-side engaging portion 305. The opening at the top of the nozzle cover 301 is expanded outward. When pushed to a certain height, the cover-side engaging portion 302 moves toward the outer wall of the frame 22 along the flat surface portion of the frame-side engaging portion 305. At this time, the cover-side engaging portion 302 is caught and engaged with one of the protrusions of the frame-side engaging portion 305. After that, when the nozzle cover 301 is further pushed into the frame 22, the cover-side engaging portion 302 engages with the frame-side engaging portion 305 at a higher position. As a result, the nozzle cover 301 can be fixed in a state where the gap between the nozzle surface of the inkjet head 100 and the nozzle cover 301 is small.

According to the inkjet head 100 having the above configuration, the nozzle cover 301 can be reliably mounted on the frame 22, and the gap between the nozzle surface and the nozzle cover 301 is set to be equal to or less than the desired thickness of the recording medium. Can be done.

Next, another embodiment of the engagement structure between the nozzle cover 301 and the frame 22 included in the inkjet head 100 will be described. FIG. 6 is also a cross-sectional view of the inkjet head 100 according to the present embodiment, showing the contours of the frame 22 and the nozzle cover 301, and omitting a detailed internal structure. FIG. 6A is a cross-sectional view taken along the lateral direction of the frame 22, and FIG. 6B is a cross-sectional view taken along the longitudinal direction of the frame 22. In the frame 22 according to the present embodiment, the frame-side engaging portion 306 as the first engaging portion formed on a part of the wall surface is formed as a recess in which the wall surface of the frame 22 is recessed inward. A plurality of recesses forming the frame-side engaging portion 306 are formed, and a saw-shaped portion is formed as a whole.

As shown in FIG. 6A, the frame-side engaging portion 306 is a plurality of protrusions formed on the outer surface of the frame 22 and having a serrated shape in the height direction. The protrusions are formed at intervals of several μm to several hundred μm. The frame-side engaging portion 305 is preferably provided over a range of 1 mm to several mm.

As shown in FIG. 6B, a plurality of frame-side engaging portions 306 are formed side by side in the height direction in the vicinity of the end portion in the longitudinal direction of the frame 22. The length in the longitudinal direction is preferably in the range of 1 mm to several mm. In FIG. 6B, frame-side engaging portions 306 are formed at a total of two locations at each of the longitudinal end portions of the frame 22, but they may also be formed at intermediate positions in the longitudinal direction. In that case, the engaging portion on the head cover side may also be formed so as to match the position of the engaging portion 306 on the frame side.

The difference from the frame-side engaging portion 305 described above is that a part of the wall surface of the frame 22 is recessed inward to form a serrated protrusion between the recesses. This protrusion is formed so as not to extend to the outside of the outer wall surface of the frame 22. Therefore, when the nozzle cover 301 is pushed up from below and fitted, the opening above the nozzle cover 301 is not expanded, and the peripheral wall of the nozzle cover 301 is expanded outward even after fitting. Never. Therefore, the outer shape of the inkjet head 100 can be reduced, and the assembling property when a plurality of inkjet heads 100 are used side by side can be improved. Moreover, the entire unit can be made smaller.

Next, another embodiment of the engagement structure between the nozzle cover 301 and the frame 22 included in the inkjet head 100 will be described. FIG. 7 is also a cross-sectional view of the inkjet head 100 according to the present embodiment, showing the contours of the frame 22 and the nozzle cover 301, and omitting a detailed internal structure. In the present embodiment, the frame-side engaging portion 303 included in the frame 22 is formed of one protrusion (claw) having a part of the outer wall of the frame 22 protruding outward.

Further, the cover-side engaging portion 307 according to the present embodiment is not a square hole formed at a predetermined height position of the nozzle cover 301, but a long and plurality of slits formed at different positions in the height direction. It is formed by a part.

When the nozzle cover 301 is covered by pushing the upper opening from the bottom surface side of the frame 22, the V-shaped portion of the nozzle cover 301 is pushed outward along the protrusion of the frame side engaging portion 303, and the nozzle cover 301 is pushed. The opening on the top surface of the is expanded. When the nozzle cover 301 is pushed upward, the frame-side engaging portion 305 is inserted into the lower slit (cover-side engaging portion 307) of any of the slits of the cover-side engaging portion 307 at the predetermined position. Engage. As a result, the nozzle cover 301 can be fixed in a state where the gap between the nozzle surface of the inkjet head 100 and the nozzle cover 301 is small. The cover-side engaging portions 307 included in the nozzle cover 301 according to the present embodiment are formed on both sides of the nozzle cover 301 in the longitudinal direction.

Since the cover-side engaging portion 307 may be capable of engaging with the frame-side engaging portion 303 of the frame 22 at any position, the cover-side engaging portion 307 is formed with a length extending to the total length in the longitudinal direction of the nozzle cover 301. You may. Further, as shown in FIG. 8, the cover-side engaging portion 307 may be formed at a position that is a part of the longitudinal direction and faces the position where the frame-side engaging portion 303 is formed. The cover-side engaging portion 307 is formed of a plurality of slit-shaped portions. If the frame-side engaging portion 303 is inserted into any of the slits, the nozzle cover 301 and the frame 22 are engaged. Since a plurality of slits are formed side by side in the height direction, the height of the nozzle cover 301 can be easily adjusted by engaging the frame-side engaging portion 303 with the slits at any of the height positions. can.

According to the inkjet head 100 having the above configuration, the nozzle cover 301 can be securely fitted to the frame 22, and the gap between the nozzle surface and the nozzle cover 301 is set to be equal to or less than the desired thickness of the recording medium. , Or the nozzle surface and the nozzle cover 301 can be brought into close contact with each other.

Next, an example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view of the main part of the device, and FIG. 11 is a side view of the main part of the device.

This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which the inkjet head 100 and the head tank 441 according to the embodiment of the present invention are integrated. The inkjet head 100 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the inkjet head 100 is mounted by arranging a nozzle array composed of a plurality of nozzles in the sub-scanning direction orthogonal to the main scanning direction and directing the ejection direction downward.

The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the inkjet head 100 to the inkjet head 100.

The supply mechanism 494 includes a cartridge holder 451 which is a filling portion for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is sent from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

This device includes a transport mechanism 495 for transporting the paper 410 as a recording medium. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

The transport belt 412 attracts the paper 410 and transports it at a position facing the inkjet head 100. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the inkjet head 100 is arranged on the side of the transport belt 412.

The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the inkjet head 100, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In this device configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is transported in the sub-scanning direction by the orbital movement of the transport belt 412.

Therefore, by driving the inkjet head 100 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is discharged to the stopped paper 410 to form an image.

As described above, since this device includes the liquid discharge head according to the present invention, it is possible to stably form a high-quality image.

Next, an embodiment of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 12 is an explanatory plan view of a main part of the unit.

This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and an inkjet among the members constituting the device for discharging the liquid. It is composed of a head 100.

A liquid discharge unit may be configured in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.

Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 13 is a front explanatory view of the unit.

This liquid discharge unit is composed of an inkjet head 100 to which the flow path component 444 is attached and a tube 456 connected to the flow path component 444.

The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 that electrically connects to the inkjet head 100 is provided on the upper part of the flow path component 444.

In the present application, the "device for discharging a liquid" is a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid toward the air or the liquid.

The "device for discharging the liquid" can also include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that discharges a liquid", an image forming device that is a device that discharges a liquid to form an image on a medium, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "material to which a liquid can adhere" means a material to which a liquid can adhere even temporarily. The material of the "material to which the liquid adheres" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or the like as long as the liquid can adhere even temporarily.

The "liquid" also includes inks, treatment liquids, DNA samples, resists, pattern materials, binders, modeling liquids and the like.

Further, the "device for discharging the liquid" includes both a serial type device for moving the liquid discharge head and a line type device for not moving the liquid discharge head, unless otherwise specified.

In addition, as a "device for ejecting liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials. There is an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid in which the above-mentioned material is dispersed in a solution through a nozzle 102a.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and is an aggregate of parts related to liquid discharge. For example, the "liquid discharge unit" includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

Here, "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, adhesion, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional component, and the mechanism may be detachably attached to each other.

For example, as a liquid discharge unit, there is a liquid discharge head and a head tank integrated, such as the liquid discharge unit 440 shown in FIG. Further, there is a case in which the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a liquid discharge head and a carriage integrated.

Further, as a liquid discharge unit, there is a liquid discharge head in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member forming a part of the scanning movement mechanism. Further, as shown in FIG. 12, there is a liquid ejection unit in which the inkjet head 100, the carriage, and the main scanning moving mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which the inkjet head 100 is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the inkjet head 100, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, as shown in FIG. 13, a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. ..

The main scanning movement mechanism shall also include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

Further, the pressure generating means used for the "liquid discharge head" is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described in the above embodiment, it is composed of a thermal actuator using an electrothermal conversion element such as a heat generating resistor, a vibrating plate, and a counter electrode. An electrostatic actuator or the like may be used.

In addition, image formation, recording, printing, printing, printing, modeling, etc. in the terms of the present application are all synonymous.

10: Image forming device 11: Device main body 12: Mechanism part 13: Carriage 14: Ink cartridge 22: Frame 24: Supply port 25: Individual liquid chamber forming substrate 100: Inkjet head 102: Nozzle substrate 102a: Nozzle 103: Individual liquid chamber Substrate 103a: Individual liquid chamber 103b: Fluid resistance part 103c: Liquid supply port 104: Holding substrate 104a: Recessed 105: Common liquid chamber 106: Damper 107: Plate 108: Buffer chamber 111: Vibrating plate 112: piezoelectric element 113: Drive circuit Member 114: Upper electrode 115: Lower electrode 116: Holding substrate opening 201: Supply part 301: Nozzle cover 302: Cover side engaging part 303: Frame side engaging part 304: Opening 305: Frame side engaging part 306: Frame side engaging part 307: Cover side engaging part

Japanese Unexamined Patent Publication No. 2015-150686

Claims (10)

A head body having a nozzle surface composed of a plurality of nozzles for ejecting droplets,
A nozzle cover that is attached to the head body and has an opening at a position facing the nozzle surface.
It is a liquid discharge head having
The head body portion is formed with a first engaging portion that engages the nozzle cover with a frame that forms a surface orthogonal to the nozzle surface.
The nozzle cover has flexibility, and a second engaging portion that engages with the first engaging portion is formed.
There are a plurality of engaging positions between the first engaging portion and the second engaging portion in the height direction of the surface.
A liquid discharge head characterized by that. The first engaging portion is a plurality of convex portions formed at intervals in the height direction of the surface and projecting from the surface.
The second engaging portion is a hole portion that can be engaged with the convex portion.
The liquid discharge head according to claim 1. The first engaging portion is a plurality of convex portions formed at intervals in the height direction of the surface and formed together with a plurality of concave portions recessed inside the surface.
The second engaging portion is a hole portion that can be engaged with the convex portion.
The liquid discharge head according to claim 1. The convex portion of the first engaging portion has a serrated cross-sectional shape.
The liquid discharge head according to claim 2 or 3. The first engaging portion is a convex portion formed on the surface, and is a convex portion.
The second engaging portion is a plurality of holes formed at intervals along the height direction of the surface.
The liquid discharge head according to claim 1. The hole has a long slit shape along a direction orthogonal to the height direction of the surface.
The liquid discharge head according to claim 5. The first engaging portion is formed at both ends in a direction orthogonal to the height direction of the surface, respectively.
The liquid discharge head according to any one of claims 1 to 6. The nozzle cover is a member integrally formed from a thin metal plate.
The liquid discharge head according to any one of claims 1 to 7. A head tank for storing the liquid to be supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying the liquid to the liquid discharge head, and a maintenance / recovery mechanism for maintaining and recovering the liquid discharge head. , At least one of the main scanning moving mechanism for moving the liquid discharging head in the main scanning direction and the liquid discharging head are integrated.
The liquid discharge unit according to any one of claims 1 to 8, wherein the liquid discharge head is the liquid discharge head. A device that drives a liquid discharge head to discharge liquid.
The device for discharging a liquid, wherein the liquid discharge head is the liquid discharge head according to any one of claims 1 to 8.

Images