JP2014054759A - Droplet discharge head, head cartridge, and image formation device - Google Patents

Abstract

Disclosed is a liquid droplet ejection head capable of reducing non-ejection or abnormal ejection, stabilizing ejection and performing high-quality image formation, and an image forming apparatus equipped with the same.
A nozzle plate 2 having a plurality of nozzles 2a, a liquid chamber 1a communicating with each nozzle, a flow path plate 1 having a fluid resistance 1b, a driving means 5 for pressurizing liquid in the liquid chamber, and a supply port 3d. In the droplet discharge head 4 having the vibration plate 3 having the common liquid chamber 1c and the frame 7 having the common liquid chamber 1c, the supply port between the common liquid chamber and the vibration plate has a filter 3f having a plurality of holes. A concave portion 2b having a smaller plate thickness than other portions was provided in a portion facing the supply port of the nozzle plate, and the concave portion was continuously formed in the same direction as the parallel direction of the liquid chambers.
[Selection] Figure 3

Description

  The present invention relates to a droplet discharge head that discharges droplets from nozzles by displacing a diaphragm by a driving unit mainly composed of piezoelectric elements, and an image forming apparatus including the droplet discharge head.

  In general, an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, and a multi-function machine such as these includes a recording head including a droplet discharge head that discharges ink droplets, and a medium (paper, recording medium). And recording medium, transfer material, recording paper, etc.) while carrying an image formation (recording, printing, printing, printing, etc. are used synonymously) by adhering ink droplets to the paper. ing. As a droplet discharge head, a plurality of nozzles that discharge ink droplets and are arranged in parallel, and a plurality of liquid chambers (pressure chamber, pressurization chamber, discharge chamber, And a diaphragm that forms at least a part of the wall surface of each liquid chamber, and the diaphragm is deformed by a piezoelectric element to change the volume of the liquid chamber. A piezoelectric recording head using a piezoelectric actuator that discharges droplets is known.

  In recent years, due to a demand for higher image quality, a multi-nozzle head having a plurality of nozzles is used as a recording head for image formation, and the droplet size discharged from each nozzle tends to be reduced. For this reason, the liquid chamber tends to be smaller, and in order to reduce the nozzle pitch, it is necessary to reduce not only the liquid chamber width direction but also the liquid chamber length direction. This is to increase the resonance frequency and eject small droplets. However, even when the liquid chamber is reduced in size, it is necessary that the drive energy of the actuator element is sufficiently propagated to the liquid chamber and that the drive energy is not propagated to the partition walls separating the plurality of liquid chambers. In addition, it is necessary to make the characteristics of the liquid droplets discharged from each nozzle uniform, and it is important to reduce the difference in volume and resistance of the liquid chambers between the recording heads. It is essential.

  Furthermore, it is known that factors other than the liquid chamber structure, such as ink viscosity, bubbles and foreign matter, have a great influence on the ejection characteristics. Due to the demand for higher quality, with regard to ink viscosity, a heat source is mounted on the recording head in order to manage the ink viscosity, or the supply amount based on the ink temperature as disclosed in, for example, “Patent Document 1”. There has been proposed a configuration for adjusting the above. Regarding the bubbles, as disclosed in, for example, “Patent Document 2”, a configuration in which a space for trapping bubbles is provided in the liquid chamber has been proposed. However, the above-described configuration is effective for ink viscosity and air bubbles, but is not effective for foreign matter contamination. Thus, for example, “Patent Document 3” discloses a configuration in which a plurality of supply ports having an opening area smaller than that of the nozzle are provided in the diaphragm. With this configuration, it is possible to reduce contamination by foreign matter after the liquid chamber assembly of the droplet discharge head is completed, and as a result, it is possible to stabilize the discharge characteristics of the recording head.

  However, in the above configuration, since the diameter of the supply port (filter diameter) formed in the diaphragm is fine, the problem is that the filter is clogged over time due to foreign matter entering from upstream or generated bubbles. There is. In this case, the liquid that should be supplied from the common liquid chamber is not supplied to the individual liquid chamber, and non-ejection or abnormal ejection occurs.

  The present invention solves the above-described problems, provides a droplet discharge head that can reduce non-discharge or abnormal discharge, stabilize discharge, and perform high-quality image formation, and an image forming apparatus including the same. With the goal.

  The invention according to claim 1 is formed in a nozzle plate having a plurality of nozzles that discharge liquid as droplets, a liquid chamber that stores the liquid and that communicates with each nozzle, and a flow path that allows the liquid to flow to the liquid chamber. A flow path plate having fluid resistance, driving means for generating pressure to pressurize the liquid in the liquid chamber, and supplying at least one wall surface of the liquid chamber to supply the liquid to the liquid chamber In the liquid droplet ejection head having a diaphragm having a supply port and a frame having a common liquid chamber for storing the liquid until it flows into the liquid chamber, the supply port between the common liquid chamber and the diaphragm The nozzle plate is provided with a recess having a thickness smaller than that of the other portion at the portion facing the supply port of the nozzle plate, and the recess is parallel to the liquid chamber. Is formed continuously in the same direction as And butterflies.

  According to the present invention, even when the filter is clogged over time, the liquid volume can be secured by providing the recess in the nozzle plate, so that the liquid can be supplied to each liquid chamber without shortage. And the occurrence of non-ejection or abnormal ejection can be suppressed.

1 is a schematic perspective view of a droplet discharge head to which an embodiment of the present invention can be applied. It is a disassembled perspective view of the droplet discharge head which can apply one Embodiment of this invention. It is a schematic sectional drawing of the droplet discharge head used for the 1st Embodiment of this invention. It is principal part sectional drawing of the droplet discharge head used for the 1st Embodiment of this invention. It is the schematic of the nozzle plate used for the 1st Embodiment of this invention. It is the schematic of the flow-path board used for the 1st Embodiment of this invention. It is the schematic of the diaphragm used for the 1st Embodiment of this invention. It is the schematic of the diaphragm used for the 2nd Embodiment of this invention. It is the schematic of the diaphragm used for the modification of the 1st Embodiment of this invention. 1 is a schematic view of an edge shooter type droplet discharge head used in an embodiment of the present invention. FIG. 1 is a schematic diagram of a side shooter type droplet discharge head used in an embodiment of the present invention. FIG. 1 is a schematic front view of an image forming apparatus to which an embodiment of the present invention can be applied. 1 is a plan view of a main part of an image forming apparatus to which an embodiment of the present invention can be applied.

  1 and 2 show a droplet discharge head to which an embodiment of the present invention can be applied. In the drawing, a droplet discharge head 41 includes a head portion 42 for discharging droplets, an electric circuit board 43 on which electronic components connected to the head portion 42 are mounted, and a tank in which ink to be supplied to the head portion 42 is accommodated. 44, the frame member 17 constituting the head portion 42, the electric circuit board 43, and the tank 44 are integrated in a laminated structure. Spaces (not shown) are provided between the frame member 17 and the electric circuit board 43 and between the electric circuit board 43 and the tank 44, and the electronic component 32 is disposed on the electric circuit board 43.

  The head portion 42 includes a nozzle plate 12 on which nozzles 11 for discharging droplets are formed, a flow path plate 14 that forms a liquid chamber 13 that communicates with the nozzles 11, and vibration that forms part of the wall surface of the liquid chamber 13. A plate 15, two piezoelectric actuators 16 for displacing the vibration plate 15, and a common liquid chamber 18 that supplies ink to each liquid chamber 13 are formed, and each piezoelectric actuator 16 is housed in the nozzle plate 12 and the flow path. And a frame member 17 that holds the plate 14 and the diaphragm 15 on the front side.

  A fluid resistance unit and a liquid chamber 13 that also serve as a supply path for supplying ink to the liquid chamber 13 and the liquid chamber 13 by the flow path plate 14 and the nozzle plate 12 bonded to the upper surface and the vibration plate 15 bonded to the lower surface. And a communication hole for communicating the nozzle 11 with each other. The nozzle 11 is formed to have a diameter of 10 to 30 μm corresponding to each liquid chamber 13, and each joining surface is joined by an adhesive layer (not shown) having a thickness of about 0.4 to 10 μm.

  The nozzle plate 12 may be made of a metal such as stainless steel or nickel, a resin such as a polyimide resin film, silicon, or a combination thereof. A water repellent film is formed on the discharge surface (surface in the discharge direction) by a known method such as a plating film or a water repellent coating in order to ensure the water repellency of the ink. The flow path plate 14 is formed with each liquid chamber 13 and fluid resistance portion by processing a stainless steel substrate by etching with an acidic etchant or mechanical processing such as pressing, and each of the communication plates is arranged at 150 dpi, for example. A plurality of communication holes for communicating the liquid chamber 13 and the nozzle 11 are formed. The vibration plate 15 is formed of a nickel metal plate in this embodiment, but may be formed of a resin member or a laminated member of a resin member and a metal member.

  Each piezoelectric actuator 16 has a multilayer piezoelectric element member 22 which is a two-row pressure generating means joined to a substrate 21. Each multilayer piezoelectric element member 22 is slitted to provide each liquid chamber. Piezoelectric element columns corresponding to 13 are formed. Each laminated piezoelectric element member 22 is connected to a flexible wiring board 23 that electrically connects the piezoelectric element columns and the electric circuit board 3. The frame member 17 is formed with an opening 17 a for accommodating the piezoelectric actuator 16 in addition to the common liquid chamber 18 described above. The flexible wiring is formed of a thin film-like member that has flexibility and can be greatly deformed, and a plurality of electric circuits are provided inward, although not shown.

  On the electric circuit board 43, the piezoelectric actuator 16, the flexible wiring board 23, and the electronic component 32 connected via the wiring pattern on the electric circuit board 43 are mounted on both surfaces of the board body 31, and the droplet discharge head 41 and In addition to the FFC connector 33 and the like for connecting to the control board of the image forming apparatus main body, an opening for passing the flexible wiring board 23 is formed.

  FIG. 3 shows a first embodiment in which the features of the present invention are employed. A droplet discharge head 4 shown in FIG. 3 includes a flow path plate 1 as a liquid chamber substrate that forms a liquid chamber 1a and a fluid resistance portion 1b, and a nozzle 2a that discharges liquid droplets bonded to the upper surface of the flow path plate 1. , A diaphragm 3 bonded to the lower surface of the flow path plate 1 and having a thin portion 3a, and a laminated piezoelectric element 5 bonded to the diaphragm 3 as a driving means for changing the internal pressure of the liquid chamber 1a. And a base substrate 6 to which the laminated piezoelectric element 5 is fixed. In FIG. 3, the adhesive layer is not shown because the thickness thereof is smaller than that of other members, and in the present embodiment, the diaphragm 3 having a convex portion 3 b and a thick portion 3 c is used. ing.

  In the present embodiment, the laminated piezoelectric element 5 is formed by alternately laminating piezoelectric material layers and internal electrodes, and is configured to pressurize the liquid in the liquid chamber 1a using a vertical displacement as the piezoelectric direction. . In the present embodiment, the laminated piezoelectric element 5 is divided into comb teeth by half-cut dicing and is alternately used as a piezoelectric element driving part and a supporting part (non-driving part). Call. Since the flow path unit is supported by the support portion, it is very effective in preventing the flow path plate 1 from being lifted by the pressure increase in the liquid chamber 1a and suppressing so-called mutual interference. Further, a structure (normal pitch structure) in which the piezoelectric element driving portions of the laminated piezoelectric element 5 in which the liquid chambers 1a are further densified is made to have the same interval as the nozzle pitch and the support portions are not formed may be employed.

  Examples of the material of the flow path plate 1 include silicon, nickel, 42 alloy, SUS304, and other stainless steel materials. A liquid-resistant thin film made of a silicon oxide film, a titanium nitride film, or an organic resin film such as a metal film or polyimide may be formed on the surface of the flow path plate 1 in contact with the liquid. By forming such a liquid-resistant thin film, the flow path plate material is less likely to elute from the liquid, and the wettability is also improved, so that bubbles do not easily stay and stable droplet discharge is possible. The layers and films in the present invention include all structures that are substantially flat.

  In the configuration shown in FIG. 3, the thickness of the flow channel plate 1 is 40 to 600 μm (the liquid chamber 1 a can be formed by stacking the flow channel plates 1), and the longitudinal length 400 to 400 of the liquid chamber 1 a. The width of the liquid chamber 1a is 1600 μm and the width is 120 to 130 μm. The width of the flow path partition is about 15 to 50 μm (liquid chamber pitch 150 dpi) at the joint surface with the diaphragm 3. As shown in FIG. 4, the thickness of the flow channel plate 1 is 100 to 600 μm (the liquid chamber 1 a can be formed by laminating the flow channel plates 1), and the longitudinal length 400 to 400 of the liquid chamber 1 a. The width may be 1200 μm and the width of the liquid chamber 1a may be 50 to 70 μm (because the liquid chamber pitch is 300 dpi).

  The nozzle plate 2 is formed of a metal material, for example, a nickel plating film by an electroforming method, and has a number of nozzles 2a that are fine discharge ports for causing droplets to fly. The internal shape (inner side shape) of the nozzle 2a is a horn shape (may be a substantially cylindrical shape or a substantially truncated cone shape), and its diameter is about 15 to 35 μm on the droplet discharge side. In the present embodiment, the nozzle 2a has a diameter of 18 to 24 μm, and the nozzle pitch of each row is 150 dpi / 300 dpi. Further, a resin material may be used as the nozzle plate 2.

  On the liquid ejection surface (nozzle surface side) of the nozzle plate 2, a water repellent treatment layer 2d subjected to a water repellent surface treatment is provided. Liquid physical properties, such as tetrafluoroethylene nickel eutectoid plating, electrodeposition coating of fluororesin, evaporative fluororesin, such as vapor-deposited fluoride pitch, and baking after solvent coating of silicon resin and fluororesin The water-repellent treatment layer 2d selected according to the above is provided to stabilize the liquid droplet shape and flight characteristics and to obtain high-quality image quality.

  The frame 7 in which the engraving that becomes the supply port 3d for supplying the liquid from the outside and the common liquid chamber 1c is formed is formed by injection molding of epoxy resin. The resin material may be polyphenylene sulfide or the like.

  In the droplet discharge head 4 configured as described above, a driving waveform (pulse voltage of 10 to 50 V) is applied to the driving unit of the laminated piezoelectric element 5 in accordance with a recording signal, whereby the driving unit is displaced in the stacking direction. Is generated, the liquid chamber 1a is pressurized through the diaphragm 3, the pressure is increased, and droplets are ejected from the nozzle 2a. Thereafter, the liquid pressure in the liquid chamber 1a decreases with the end of the droplet discharge, and a negative pressure is generated in the liquid chamber 1a due to the inertia of the liquid flow and the discharge process of the driving pulse, and the liquid filling process is started. Transition. At this time, the liquid supplied from the liquid tank flows into the common liquid chamber 1c, and is filled into the liquid chamber 1a from the common liquid chamber 1c via the supply port 3d through the fluid resistance portion 1b.

  The fluid resistance portion 1b is effective in attenuating residual pressure vibration after ejection, but has resistance against refilling (refilling) due to surface tension. By appropriately selecting the fluid resistance portion 1b, it is possible to balance the attenuation of the residual pressure and the refill time, and to shorten the time (drive cycle) until shifting to the next droplet discharge operation.

  In the above-described configuration, as the shapes of the convex portion 3b and the thick portion 3c, there is a configuration in which the periphery of the convex portion 3b is surrounded by the thin portion 3a and the periphery is surrounded by the thick portion 3c. As this forming method, there is a method of stacking two nickel plating films by an electroforming method, and protrusions such as ribs may be formed by this electroforming method.

  Moreover, as the diaphragm 3, the structure which has a metal layer and a resin layer can be considered. As a member constituting the metal layer, nickel, 42 alloy, and SUS304 are conceivable. By forming a metal film such as silicon oxide or titanium on the surface, there is no need to worry about moisture permeation of the liquid. When the diaphragm 3 is a resin layer, the rigidity of the thin portion 3a is lower than that of the metal layer, so that the displacement efficiency of the laminated piezoelectric element 5 is not hindered. Moreover, when the flow path plate 1 is a metal, the bonding strength between the resin layer and the metal is enhanced as compared with the bonding between the metals. The resin layer may be a rolled film, which can provide a highly reliable product with almost no defects such as pinholes even when the thickness is reduced.

  In the present embodiment, a treatment showing affinity for the adhesive, such as forming a hydroxyl group or a silicon oxide thin film layer, may be performed in the bonding region between the vibration plate 3 and the laminated piezoelectric element 5 as the driving means. Conceivable. The silicon oxide thin film layer is formed by a method in which film formation can be performed at a temperature within a range in which heat is not relatively applied, that is, no thermal influence is generated on the diaphragm 3. Specifically, sputtering, ion beam vapor deposition, ion plating, CVD (chemical vapor deposition), P-CVD (plasma vapor deposition) and the like are suitable. In the present embodiment, the silicon oxide film is generated by oxidizing the sputtered film after sputtering of silicon. It is advantageous from the viewpoint of process time and material cost that the silicon oxide film has a minimum necessary thickness within a range in which adhesion can be secured. In this embodiment, the thickness of the silicon oxide film is used in the range of 10 to 2000 mm.

  In the water repellent treatment of this embodiment, the water repellent film is formed by a known method such as a plating film or a water repellent coating. As a water repellent treatment method, a spin coater, a roll coater, a screen printing, a spray coater, or the like can be used. In addition, a method of forming a film by vacuum deposition is also used. According to this method, the adhesion of the water repellent film is improved. In the present embodiment, the thickness of the thin part is 2 to 10 μm, and the length of the thin part region in the liquid chamber short direction is 10 to 50 μm.

  In this embodiment, polyphenylene sulfide (PPS) resin is used as the resin layer. However, other polymer materials that can be stretched, such as polyimide (PI) resin, polyetherimide (PEI) resin, polyamideimide (PAI) resin, are used. , Polybalavanic acid (PPA) resin, polysulfone (PSF) resin, polyethersulfone (PES) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, polyolefin (APO) resin, polyethylene naphthalate ( PEN) resin, aramid resin, polypropylene resin, vinylidene chloride resin, polycarbonate resin, or the like may be used.

  In FIG. 3, a filter 3 f having a plurality of holes for removing foreign matters is provided in the supply port 3 d of the diaphragm 3 constituting the droplet discharge head 4. The diameter of the hole of the filter 3f is about 5 to 20 μm, and is formed to be smaller than the diameter of the nozzle 2a. In the present embodiment, with respect to the supply port 3d formed in the diaphragm 3, almost the entire region facing the common liquid chamber 1c is set as a region where the filter 3f is provided. Here, the filter 3f may be provided with a region for blocking the flow of the adhesive.

  In the part of the nozzle plate 2 facing the filter 3f, a recess 2b having a thickness reduced compared to other parts is formed. As shown in FIG. 3, the recess 2b is formed in the liquid chamber 1a. It is formed continuously in the same direction as the parallel direction. When a metal such as stainless steel is used as the nozzle plate 2, it can be manufactured by controlling the plate thickness by a method such as etching, and when a metal such as nickel is used, for example, by electroforming. Further, the recess 2b may be continuous in the parallel direction of the liquid chambers 1a, may have a shape partitioned by several channels to several tens of channels, and the shape of the recess 2b may be rectangular or tapered. .

  The filter 3f may be provided in substantially the entire region of the supply port 3d facing the common liquid chamber 1c or may be provided corresponding to each liquid chamber 1a. Since the diameter of the hole of the filter 3f is fine, there is a high possibility that the filter 3f will be clogged with time due to foreign matter entering from the upstream side or generated bubbles. In this case, the liquid that should be supplied from the common liquid chamber 1c is not supplied to the liquid chamber 1a, and non-discharge or abnormal discharge is likely to occur. However, the liquid volume is secured by providing the nozzle plate 2 with the recess 2b. Therefore, the liquid can be supplied to each liquid chamber 1a without shortage, and the occurrence of non-discharge or abnormal discharge can be suppressed.

FIG. 4A shows a state in which the droplet discharge head 4 is superposed on the nozzle plate 2, the flow path plate 1, and the vibration plate 3 from above, and FIG. 4B shows 1 in FIG. 4A. 4 shows a cross section of the liquid chamber 1-1, and FIG. 4C shows a cross section of the filter 3f and the recess 2b, which are 2-2 cross sections of FIG. 4A.
FIG. 5 shows the nozzle plate 2, in which a plurality of nozzles 2 a and recesses 2 b are formed. The recess 2b is formed at a position facing the supply port 3d.

FIG. 6 shows the flow path plate 1, and the flow path plate 1 has three areas: a liquid chamber 1a area, a fluid resistance portion 1b area, and a damper chamber 1d area. As a method for forming the flow path plate 1, each region 1 a, 1 b, 1 d includes mechanical processing such as press processing or etching processing.
FIG. 7 shows the diaphragm 3. In the present embodiment, the hole is formed over the entire area of the filter 3f region, but the outer periphery of the filter 3f region has a hole so that the hole of the filter 3f is not clogged due to the flow of adhesive or the like. There may be no area. As this area | region, 5-50 micrometers is preferable.

  FIG. 8 shows a filter 3e used in the second embodiment of the present invention. This filter 3e is different from the filter 3f described above only in that it is provided continuously in the same direction as the parallel direction of the liquid chambers 1a, that is, in correspondence with the recess 2b. Are the same. With this configuration, the increase in the number of holes makes it difficult for filter clogging to occur over time, and it is possible to further suppress the occurrence of non-ejection or abnormal ejection as compared with the first embodiment.

  FIG. 9 shows the hole shape of the filter 3f. FIG. 9B shows a straight type A, and even such a hole shape can sufficiently serve as a filter. FIG. 9C shows a tapered type B whose diameter gradually decreases from the common liquid chamber 1c side to the damper chamber 1d side in the thickness direction, that is, from the inner side to the outer side. In the flow of liquid from the common liquid chamber 1c side to the damper chamber 1d side, foreign matter can be caught by the filter 3f, and discharge stability can be improved. Further, in the flow of liquid from the damper chamber 1d side to the common liquid chamber 1c side, since the hole diameter on the damper chamber 1d side is small, the fluid resistance of the filter 3f is high, and the effect of attenuating the residual pressure can be improved. Thereby, a high-quality and long-life droplet discharge head can be provided.

  An inkjet head, which is a droplet discharge head to which the present invention can be applied, includes an edge shooter method in which the shape from the ink flow path to the discharge port is linear, and a side shooter method in which the direction of the ink flow path differs from the direction of the discharge port Any of these may be used. Below, an example of this inkjet head is shown.

  First, an edge shooter type inkjet head will be described. In FIG. 10 showing an edge shooter type inkjet head 50, the inkjet head 50 includes an ejection energy generator 57 (an electrode for applying an ejection signal to the generator 57 and a protective layer provided on the generator 57 as required). And a top plate 53 constituting a cover of the flow path 54 and a wall material 52 constituting the side wall of the flow path 54 and the orifice 55 and a top plate 53 constituting the cover of the flow path 54.

  In the inkjet head 50, when a recording signal is applied to the ejection energy generator 57 via an electrode (not shown) in a state where the ink is stored in the flow path 54 from a liquid chamber (not shown) in which ink is stored, the generator The discharge energy generated from 57 acts on the ink in the flow path 54 above the generator 57 (discharge energy operation portion), and as a result, the ink is discharged from the orifice 55 as droplets. The ejected ink droplets adhere to a recording material such as recording paper fed in front of the orifice 55.

  Such an edge shooter-type ink jet head has the advantage that each part can be precisely miniaturized, the orifices can be multi-sized or miniaturized, and the mass productivity is high. On the other hand, there is a limit to the response frequency when ejecting ink droplets and the flying speed of ink droplets. In addition, bubbles are generated in the ink as the electrothermal conversion element generates heat. The bubbles contract due to a decrease in temperature, and the discharge energy generator 57 is gradually destroyed by an impact when the bubbles disappear in the vicinity of the discharge energy generator 57. Is done. This phenomenon is called a cavitation phenomenon, and is particularly remarkable in an edge shooter type ink jet head. For this reason, the edge shooter type inkjet head has a relatively short life.

  Next, a side shooter type inkjet head will be described. In FIG. 11, which shows a side shooter type inkjet head 60, the inkjet head 60 is provided with an orifice 65 in a top plate 63, an ink flow direction 61 to an ejection energy operating portion in a flow path 64, and an opening central axis of the orifice 65. 62 is a right angle.

  With the above-described configuration, it is possible to more efficiently convert the energy from the ejection energy generator 67 into the formation of ink droplets and their flying kinetic energy, and the structural advantage that the meniscus can be quickly restored by supplying ink. This is particularly effective when a heating element is used for the discharge energy generator 27. Further, the side shooter method can avoid the occurrence of a so-called cavitation phenomenon, which is a problem in the edge shooter method, in which the discharge energy generator is gradually destroyed by the impact when the bubbles disappear. In other words, if the bubble grows and reaches the orifice in the side shooter system, the bubble is brought into the atmosphere, and the bubble does not contract due to the temperature drop. For this reason, there is an advantage that the life of the inkjet head is long.

  Next, the image forming apparatus 100 including the droplet discharge head 4 or the inkjet heads 50 and 60 described above will be described. 12 and 13, a carriage 103 is slidably held by a guide rod 101 and a guide rail 102 that are stretched on left and right side plates (not shown), and the main scanning motor 104 is actuated via a timing belt 105. The carriage 103 is moved and scanned in the main scanning direction indicated by an arrow 13. On the carriage 103, for example, a recording head 107, which is four droplet ejection heads that eject droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K), includes a plurality of liquids. The droplet discharge ports are arranged in a direction orthogonal to the main scanning direction, and are mounted with the droplet discharge direction facing downward. A droplet discharge head using a piezoelectric actuator such as a piezoelectric element is used.

  In addition, a sub tank 108 for supplying ink of each color to the recording head 107 is mounted on the carriage 103 for each color. Each sub tank 108 is supplemented with ink from an ink cartridge as a main tank via an ink supply tube (not shown). In this embodiment, the sub tank 108 and the recording head 107 constitute the head cartridge 106. However, a configuration in which the sub tank 108 is provided separately, a configuration in which the ink cartridge is mounted on the carriage 103 without using the sub tank 108, and the like are employed. Also good.

  Under the image forming apparatus 100, a paper feeding unit that feeds the paper 112 stacked on a paper stacking unit (pressure plate) 111 such as a paper feeding cassette 110 is disposed. This paper feeding unit has a half-moon roller-shaped paper feeding roller 113 for separating and feeding the paper 112 one by one from the paper stacking unit 111, and a separation pad 114 made of a high friction resistance member disposed opposite to the paper feeding roller 113. The separation pad 114 is urged toward the paper feed roller 113 side.

  Further, as a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 that electrostatically attracts and transports the paper 112, and a guide 115 from the paper feed unit. A counter roller 122 that holds and conveys the paper 112 to be conveyed with the conveyance belt 121, a conveyance guide 123 that changes the direction of the paper 112 that is fed substantially vertically upward to substantially follow the conveyance belt 121, and a presser A tip pressure roller 125 urged toward the conveyor belt 121 by the member 124, a charging roller 126 as a charging unit for charging the surface of the conveyor belt 121, and the like are provided.

  A conveyance belt 121 made of an endless belt is stretched between a conveyance roller 127 and a tension roller 128, and the driving force from the sub-scanning motor 131 is transmitted through the timing belt 132 and the timing roller 133. The transport roller 127 circulates in the sub-scanning direction, which is the belt traveling direction in FIG. A guide member 129 is provided on the back side of the conveyance belt 121 in correspondence with an image forming area formed by the recording head 107. As shown in FIG. 13, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 that detects the rotation of the slit disk 134 is provided in the vicinity of the slit disk 134. And the sensor 135 constitute an encoder 136.

  The charging roller 126 is in contact with the surface layer of the conveyor belt 121 and is driven to rotate as the conveyor belt 121 travels, and a load of 2.5 N is applied to both ends of the support shaft as pressure. An encoder scale 142 having slits as shown in FIG. 12 is disposed in front of the carriage 103, and an encoder sensor 143 made up of a transmission type photosensor for detecting the slits of the encoder scale 142 is disposed on the front surface of the carriage 103. It is arranged. Thus, an encoder 144 that detects the position of the carriage 103 in the main scanning direction (position relative to the home position) is configured.

  As a paper discharge unit that discharges the paper 112 recorded by the recording head 107, a separation unit that separates the paper 112 from the conveyance belt 121, a paper discharge roller 152 and a paper discharge roller 153, and a paper discharge unit that stocks the paper 112 to be discharged. A paper tray 154 is provided. A double-sided paper feeding unit 161 is detachably provided on the back side of the apparatus. The double-sided paper feeding unit 161 takes in and reverses the paper 112 returned by the reverse rotation of the transport belt 121 and feeds it again between the counter roller 122 and the transport belt 121.

  In the image forming apparatus 100 configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and the conveyance belt 121 and the counter It is sandwiched between the rollers 122 and conveyed, and further, the leading end is guided by the conveying guide 123 and pressed against the conveying belt 121 by the leading end pressing roller 125, and the conveying direction is changed substantially at right angles.

  At this time, an alternating voltage is applied from a high voltage power supply to the charging roller 126 by a control circuit (not shown) so that a positive output and a negative output are alternately repeated, and the conveying belt 121 is in an alternating charging voltage pattern, that is, in a circumferential direction. In the sub-scanning direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 112 is fed onto the conveyance belt 121 in which plus and minus are alternately charged, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is moved in the sub-scanning direction by the circumferential movement of the conveyance belt 121. It is conveyed to.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103, droplets are ejected onto the stopped sheet 112 to record one line, and after the sheet 112 is conveyed by a predetermined amount, The following recording operation is performed. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 reaches the recording area, the recording operation is finished and the paper 112 is discharged to the paper discharge tray 154.

  In the case of double-sided image formation, the recording belt 112 is fed into the double-sided paper feeding unit 161 by rotating the conveyor belt 121 in reverse when the recording on the front surface (surface on which image formation is first performed) is completed. 112 is reversed (in a state where the back surface becomes the image forming surface), and is fed again between the counter roller 122 and the transport belt 121, and is controlled onto the transport belt 121 in the same manner as described above by performing timing control. After image formation, the paper is discharged to a paper discharge tray 154.

  The image forming apparatus according to the present invention can be applied to a printer, a facsimile, a copying machine, a complex machine of these, and the like, and a liquid droplet ejection head that ejects a liquid other than ink, such as a DNA sample, a resist, a pattern material, and the like. It can also be applied to a head cartridge and an image forming apparatus including these.

1 Channel plate (liquid chamber substrate)
DESCRIPTION OF SYMBOLS 1a Liquid chamber 1b Fluid resistance 1c Common liquid chamber 2 Nozzle plate 2a Nozzle 2b Recessed part 3 Diaphragm 3d Supply port 3e, 3f Filter 4 Droplet discharge head 5 Drive means (laminated piezoelectric element)
7 Frame 50, 60 Droplet discharge head (inkjet head)
100 Image forming apparatus 106 Head cartridge 107 Liquid droplet ejection head (recording head)

JP 2006-306066 A JP 2008-87464 A JP-A-2005-238531

Claims (5)

A nozzle plate having a plurality of nozzles for discharging liquid as droplets, a liquid chamber for storing the liquid and communicating with the nozzles, and a flow path having fluid resistance formed in a flow path for flowing the liquid to the liquid chamber A plate, drive means for generating pressure to pressurize the liquid in the liquid chamber, and a diaphragm having a supply port for forming at least one wall surface of the liquid chamber and supplying the liquid to the liquid chamber; A droplet discharge head having a frame having a common liquid chamber for storing the liquid until it flows into the liquid chamber;
It has a filter having a plurality of holes in the supply port between the common liquid chamber and the diaphragm, and the portion of the nozzle plate facing the supply port has a plate thickness compared to other portions. A liquid droplet ejection head, wherein a thin concave portion is provided, and the concave portion is continuously formed in the same direction as the parallel direction of the liquid chambers. The droplet discharge head according to claim 1,
The droplet discharge head, wherein the filter is continuously provided in the same direction as the parallel direction of the liquid chambers. The droplet discharge head according to claim 1 or 2,
The droplet discharge head, wherein the hole has a tapered shape.   A head cartridge comprising the droplet discharge head according to claim 1.   An image forming apparatus comprising the droplet discharge head according to claim 1.

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