JP5338715B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

  The present invention particularly relates to a liquid discharge head and an image forming apparatus having a diaphragm member.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. Devices are known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar one, but includes an image given to a three-dimensionally formed image, and an image formed by three-dimensionally modeling a solid itself.

  As a conventional liquid discharge head, a piezoelectric body as pressure generating means for generating pressure by pressurizing ink, which is liquid in a liquid chamber, for example, a stacked piezoelectric element in which piezoelectric layers and internal electrodes are alternately stacked is used. A piezoelectric actuator that deforms the deformable vibration region of the vibration plate member that forms the wall surface of the liquid chamber by the displacement of the laminated piezoelectric element in the direction d33 or d31, and changes the volume and pressure of the liquid chamber to generate droplets. A so-called piezoelectric head for discharging is known. Further, as a liquid discharge head using a diaphragm member, there is an electrostatic type head or the like.

  As a diaphragm member (also referred to as a diaphragm) used for such a liquid discharge head, for example, a member formed by electroforming is known.

  By the way, in the image forming apparatus, the nozzle pitch tends to be small for high-speed and high-resolution recording, and as a result, the pitch between the liquid chambers is also small. As the pitch between the nozzles and the liquid chambers becomes narrower, mutual interference between adjacent bits increases, resulting in unstable discharge or defective discharge. In order to suppress this interference between adjacent bits and to obtain efficient diaphragm displacement, it is necessary to reduce the thickness of the diaphragm region (diaphragm part) of the diaphragm member. There arises a problem that it is likely to occur.

  In order to suppress the residual vibration of the ink in the common liquid chamber, the wall surface of the common liquid chamber of the diaphragm member may be a deformable region (damper part), and the compliance of the damper part may be increased. In order to increase the compliance, it is necessary to reduce the thickness of the damper portion or to increase the area. When the film thickness is reduced, pinholes are likely to occur as described above, and even if the area is increased, pinholes are likely to be generated stochastically.

  When such a pinhole is generated in the diaphragm portion of the diaphragm member, when the ink in the liquid chamber is pressurized, the ink leaks from the pinhole, causing an actuator malfunction or the like.

  In view of this, as a countermeasure against pinholes in the diaphragm member which is a Ni electroformed part, a resin is applied to the metal layer to fill the pinholes with the resin.

  Patent Document 1 also discloses a configuration in which a water-repellent film is formed on both surfaces or one surface of the diaphragm portion of the diaphragm member although the problem to be solved is different.

JP 2009-066794 A

  However, in order to completely fill the pinhole by applying the resin, there is a problem that the coating film thickness is increased and the vibration characteristics (displacement efficiency) of the diaphragm portion are lowered. Further, as disclosed in Patent Document 1, when a water repellent layer is formed on the liquid chamber side surface of the diaphragm member, the filling property at the time of initial filling is reduced, bubbles remain, and ejection failure (discharge failure or There is a problem that it is easy to cause an injection bend and the like, and the bonding property with the flow path member forming the liquid chamber is also lowered.

  The present invention has been made in view of the above problems, and prevents leakage of liquid even if pinholes occur while suppressing a decrease in displacement efficiency of the diaphragm member, a decrease in initial filling property, and a decrease in bondability. It aims to be able to prevent.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A nozzle for discharging droplets;
A liquid chamber in communication with the nozzle;
And a rotation plate member vibration that form a part of the wall of the liquid chamber,
The part forming a part of the wall surface of the liquid chamber in the diaphragm member has a thin part and a thick part,
The thin portion of the diaphragm member has a structure of at least three layers,
It was set as the structure by which the intermediate | middle layer between the surface layers of both sides was formed with the water repellent layer.

  The image forming apparatus according to the present invention includes the liquid discharge head according to the present invention.

According to the liquid ejection head according to the present invention, reduction in the displacement efficiency of the vibration rotation plate member, deterioration of the initial filling property, while suppressing deterioration in bonding property, even if pinholes are generated can prevent leakage of liquid.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, high reliability can be obtained and a high-quality image can be formed.

FIG. 4 is an exploded perspective view illustrating an example of a liquid discharge head according to the present invention. It is sectional explanatory drawing which follows the direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head. It is sectional explanatory drawing of an example along the nozzle arrangement direction (liquid chamber short direction) of the head. It is sectional explanatory drawing of the other example along the nozzle arrangement direction (liquid chamber short direction) of the head. It is sectional explanatory drawing of one liquid chamber part with which it uses for description of the diaphragm member of this invention. It is an expanded sectional explanatory view of the diaphragm member. It is explanatory drawing with which it uses for description of an example of the manufacturing process of the 1st layer of the diaphragm member. It is explanatory drawing with which it uses for description of the meniscus holding force of the pinhole by the 2nd layer of the diaphragm member. 1 is a schematic configuration diagram illustrating an overall configuration of a mechanism unit of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. It is a whole block diagram which shows the other example of the image forming apparatus which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional explanatory view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIGS. 3 and 4 are nozzle arrangement directions of the head. FIG. 4 is an enlarged sectional explanatory view of one liquid chamber portion.

  The liquid discharge head includes a flow path plate (flow path member, flow path substrate, liquid chamber substrate) 1 formed of a SUS substrate, and a vibration plate member 2 that forms a vibration plate bonded to the lower surface of the flow path plate 1. And a nozzle plate 3 joined to the upper surface of the flow channel plate 1, and a plurality of nozzles 4 that discharge liquid droplets (liquid droplets) thereby communicate with each other via a nozzle communication path 5. A plurality of liquid chambers (also referred to as a pressurized liquid chamber, a pressure chamber, a pressurized chamber, a flow path, etc.) 6, a fluid resistance section 7 that also serves as a supply path for supplying ink to the liquid chamber 6, and the fluid resistance section A communication part 8 communicating with the liquid chamber 6 is formed via the ink supply 7, and ink is supplied from the common liquid chamber 10 formed in the frame member 17 described later via the supply port 9 formed in the diaphragm member 2 in the communication part 8. To do.

  The flow path plate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path plate 1 is formed by etching the SUS substrate with an acidic etchant or machining such as punching (pressing) to open openings such as the communication path 5, the pressurized liquid chamber 6, and the fluid resistance portion 7. Each is formed. The flow path plate 1 can be formed by etching a single crystal silicon substrate, for example.

  Although details will be described later, the vibration plate member 2 has deformable vibration regions (diaphragm portions) 2a that form part of the wall surfaces corresponding to the liquid chambers 6, and the vibration region 2a includes the vibration member 2a. Electro-mechanical conversion as drive means (actuator means, pressure generating means) is provided with island-shaped convex portions 2b on the outer surface (opposite side to the liquid chamber 6), and the island-shaped convex portions 2b deform the vibration region 2a. A piezoelectric actuator 100 including an element is disposed.

  This piezoelectric actuator 100 has a plurality of (here, two) laminated piezoelectric members 12 bonded to an adhesive on a base member 13, and the piezoelectric member 12 is processed into a single piezoelectric element by machining a groove by half-cut dicing. A required number of piezoelectric element columns 12A and 12B are formed in a comb shape at a predetermined interval with respect to the member 12. The piezoelectric element columns 12A and 12B of the piezoelectric member 12 are the same, but the piezoelectric element column that is driven by giving a drive waveform is used as the drive piezoelectric element column 12A, and the piezoelectric element is used as a simple column without giving the drive waveform. The columns are distinguished as non-driving piezoelectric element columns 12B. Then, the upper end surface (joint surface) of the drive piezoelectric element column 12 </ b> A is joined to the island-shaped convex portion 2 b of the diaphragm member 2. Further, the upper end surface of the non-driving piezoelectric element column 12B is joined to the thick part (same thickness as the island-shaped convex part 2b) 2c of the diaphragm member 2 at a position corresponding to the liquid chamber interval wall 6A.

  Here, the piezoelectric member 12 is obtained by alternately stacking the piezoelectric material layers 21 and the internal electrodes 22A and 22B. The internal electrodes 22A and 22B are respectively substantially perpendicular to the end face, that is, the diaphragm member 2 of the piezoelectric member 12. Pulled out to the side surface (surface along the stacking direction), connected to the individual external electrode 23 and the common external electrode 24 formed on this side surface, and applying a voltage between the external electrodes 23, 24 causes displacement in the stacking direction. . The inner common external electrode 24 is drawn out to the end face on the individual external electrode 23 side through the internal electrode 22C provided in the non-drive portion of the piezoelectric member 12.

  The piezoelectric member 12 is connected to an FPC 15 which is a flexible wiring board as a flexible power supply member (wiring member) for supplying a driving signal to the driving piezoelectric element column 12A. Although not shown, the FPC 15 is mounted with a driver IC (driving circuit) that applies a driving waveform to the driving piezoelectric element column 12A, and the FPC 15 is fixed to the base member 13 with a resin member 16.

  Here, as described above, the piezoelectric element columns 12A and 12B of the piezoelectric member 12 are the same, but the piezoelectric element column to be driven by applying a driving waveform is not provided with the driving piezoelectric element column 12A. As shown in FIG. 3, the piezoelectric element column 12B used as a simple support column is a non-drive piezoelectric element column 12B, and the drive piezoelectric element column 12A and the support piezoelectric element column 12B are alternately used as a bi-pitch configuration. As shown in FIG. 4, it is possible to adopt a normal pitch configuration in which all the piezoelectric element columns are used as the driving piezoelectric element columns 12A.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the respective liquid chambers 6 and bonded to the flow path plate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  Further, a frame member 17 formed by injection molding with epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the piezoelectric actuator 100 composed of the piezoelectric element 12, the base member 13, the FPC 15, and the like. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port 19 for supplying ink from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as a cartridge.

  In the liquid discharge head configured as described above, for example, when driven by a punching method, a driving pulse voltage of 20 to 50 V is selectively applied to the driving piezoelectric element column 12A according to an image recorded from a control unit (not shown). Is applied to the piezoelectric element column 12A to which the pulse voltage is applied, and the vibration region 2a of the vibration plate 2 is deformed in the direction of the nozzle plate 3, and the liquid chamber 6 changes its volume (volume). A liquid droplet is discharged from the nozzle 4 of the nozzle plate 3 by pressurizing the liquid. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, when the voltage application to the piezoelectric element column 12A is turned off, the diaphragm 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. . At this time, ink is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  In addition to the above-described pushing, the liquid ejection head is not limited to the pulling method (a method of releasing the diaphragm 2 from the pulled state and pressurizing it with a restoring force), and the pulling-pushing method (the diaphragm 2 at the intermediate position). It is also possible to drive by pulling from this position and then extruding.

Therefore, details of the diaphragm member in the liquid discharge head will be described with reference to FIGS. 5 is a cross-sectional explanatory view of a portion corresponding to one liquid chamber, and FIG. 6 is an enlarged cross-sectional explanatory view of the diaphragm member.
The diaphragm member 2 includes a first layer 2A made of a metal layer on the surface on the actuator (piezoelectric member 12) side, and a second layer (intermediate layer) 2B made of a water-repellent layer formed on the first layer 2A. A three-layer structure is formed with a third layer (bonding layer) 3C that is a surface layer on the liquid chamber side formed on the second layer 2B.

  The first layer 2A is formed by Ni electroforming (electroforming method), and the island-shaped protrusions 2b are integrally provided.

  The manufacturing process of the first layer 2A will be described with reference to FIG. A first layer 42 for forming a part of the thin portion (diaphragm portion) 2a is formed on the electroformed support substrate 41 as shown in FIG. 5A, and a thick portion (island) is formed as shown in FIG. By forming a resist pattern 44 in which the portion corresponding to the space between the convex portion 2b and the thick portion 2c) becomes a window and performing, for example, nickel electroforming, the first layer 42 is formed as shown in FIG. Then, nickel is deposited and deposited to form a nickel layer 45. Further, by continuing the electroforming, the nickel layer 45 grows until it protrudes from the window as shown in FIG. The so-called overhang portion is also enlarged in the surface direction of 44. If this process is continued, the nickel layer 45 further extends in the thickness direction and the planar direction as shown in FIG. 5E, and after the electroforming is completed at a predetermined growth stage, the pattern 44 is removed. As a result, as shown in FIG. 5F, a metal film (plating film) having island-shaped thick portions (island-shaped convex portions 2b, thick-walled portions 2c) surrounded by concave portions is obtained. It is done.

  By using such a manufacturing method, the thin part which comprises the diaphragm part 2a of the diaphragm member 2, and the thick part which comprises the island-like convex part 2b and the thick part 2c can be produced in the same process. Moreover, photolithography can be used for pattern formation of the thick portion, and high pattern accuracy can be obtained.

  In the present invention, a water repellent layer (second layer 2B) and a bonding layer (third layer 2C) are sequentially formed with a thickness of, for example, 100 nm on the side of the first layer 2A where the flow path plates are bonded. ing.

  The second layer (intermediate layer) 2B is a water-repellent layer formed of, for example, a perfluoropolyether having alkoxysilane, silicone, or a PTFE eutectoid plating film.

  Among these, as a method of forming a perfluoropolyether having alkoxysilane as a water repellent layer, Optool DSX (trade name, manufactured by Daikin Industries, Ltd.) made of the same material is vacuum-deposited at 200 to 400 ° C. Necessary water repellency for the ink can be obtained. The deposition conditions are such that the OPTOOL DSX stock solution is depressurized to about 10-1 Pa with a rotary pump, and the temperature is gradually raised from room temperature to about 450 ° C. in this state. The film after vapor deposition is obtained by performing a heat drying treatment at approximately 70 ° C. for 10 minutes.

  The water-repellent layer forming the second layer 2B suppresses ink leakage even when pinholes are generated in the first layer 2A. That is, as shown in FIG. 8, the holding force (meniscus holding force) of the ink meniscus 52 in the pinhole 51 is 2πaγcosθ, where the pinhole radius a, the surface tension γ of the ink, and the contact angle between the ink and the substrate are θ. Can be expressed as If this meniscus holding force is greater than the force due to ink pressure, ink leakage can be suppressed. In order to increase the meniscus holding force, it is necessary to increase the contact angle θ. By providing the water repellent layer (second layer 2B), a large contact angle θ can be obtained, and the ink from the pinhole 51 can be obtained. Leakage can be suppressed.

  Here, the thickness of the water-repellent layer (second layer 2B) is preferably several nm and about a monomolecular film. By doing in this way, it becomes a water-repellent layer firmly bonded to Ni, and adhesion to the bonding layer (third layer 2C) is also improved.

The third layer (bonding layer) 2C is made of, for example, SiO ₂ .

As a method for forming the SiO ₂ layer,
(1) SiO ₂ is evaporated in vacuum to form a thin film. Or a vacuum deposition method in which Si is evaporated and passed through oxygen plasma to form a dielectric on the substrate,
(2) An oxide sputtering method in which SiO ₂ is used as a target material and atoms and clusters are knocked out with Ar plasma or the like to form a thin film on a substrate,
(3) a reactive sputtering method in which a thin film is formed on a substrate while using a Si target as a raw material and participating in a reactive gas containing oxygen;
(4) A meta mode sputtering method in which a SiO ₂ thin film is formed by repeatedly performing oxidation in a different zone from sputtering-metal thin film formation with an Si target while rotating the substrate.
Etc.

Thus, when the perfluoropolyether layer having alkoxysilane is used as the second layer 2B and the SiO ₂ layer is used as the third layer 2C, both layers can be continuously formed in a vacuum atmosphere, so the productivity is high and the film quality is high. A three-layer film with stable interlayer adhesion can be formed.

  Further, when the eutectoid plated film of PTFE is adopted as the second layer 2B and the same Ni electroformed film as the first layer is adopted as the third layer 2C, the third layer in the production process described in FIG. By sequentially plating the layer 2C, the second layer 2B, and the first layer 2A, a three-layer film having high interlayer adhesion can be formed.

  By forming the third layer 2C on the water repellent layer, when the diaphragm member 2 and the flow path plate 1 are bonded to each other by adhesive, the wettability of the adhesive can be improved and bonding can be performed satisfactorily. Without the bonding layer, the wettability between the water-repellent layer (second layer 2B) and the adhesive is extremely poor, leading to poor bonding.

  Here, the intermediate layer (second layer 2B) of the diaphragm member 2 has higher water repellency than the metal layer (first layer 2A) which is the surface layer opposite to the liquid chamber 6, and the intermediate layer (second layer). The layer 2B) has a higher water repellency than the metal layer (third layer 2C) which is the surface layer on the liquid chamber 6 side.

  By making the intermediate layer a water-repellent layer as described above, there is no need to form a layer thick enough to fill the pinhole, and the meniscus can be sufficiently retained even with a thin film deposition method such as sputtering. The leakage of ink from the pinhole can be suppressed by the force. Thereby, the fall of the displacement efficiency of a diaphragm member can be reduced. In addition, a bonding layer can be provided on the bonding surface side to be bonded to the flow path member, and it is possible to prevent a decrease in initial ink filling property and a decrease in bonding strength.

  As described above, the vibration region of the diaphragm member has a structure of at least three layers, and the intermediate layer between the surface layers on both sides is formed of a water-repellent layer. The liquid leakage can be prevented even if pinholes are generated, while suppressing the decrease in the initial state, the decrease in the initial filling property, and the decrease in the bonding property.

  The liquid discharge head according to the present invention can also be configured as a head-integrated cartridge or a cartridge-integrated head in which a cartridge for supplying ink to the head is integrated. In the above embodiment, the example in which the diaphragm member has a three-layer structure has been described. However, the diaphragm member may have a layer structure of four or more layers. In this case, at least one intermediate layer other than the surface layers on both sides is used. May be a water repellent layer.

Next, an example of the image forming apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 9 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 10 is a plan view for explaining a main portion of the mechanism portion.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes a plurality of recording heads 234 including the liquid discharge head unit according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows consisting of these nozzles are arranged in the sub-scanning direction orthogonal to the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching liquid ejection heads 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a has a black (K) droplet. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. . Note that, here, a two-head configuration is used to eject four color droplets, but a liquid ejection head for each color may be provided.

  The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 235” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridge 210 of each color by the supply unit 224 via the supply tube 236 of each color.

  On the other hand, as a paper feed unit for feeding the paper 242 loaded on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feed) that feeds the paper 242 from the paper stacking unit 241 one by one. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 for maintaining and recovering the nozzle state of the recording head 234 is disposed in a non-printing area on one side in the scanning direction of the carriage 233. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge thickened ink. Yes.

  In addition, in the non-printing area on the other side of the carriage 233 in the scanning direction, idle ejection that receives droplets when performing idle ejection that ejects droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like A receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, it is possible to perform highly reliable and stable droplet discharge and to form a high-quality image at high speed. Can do.

Next, another example of the image forming apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. In addition, FIG. 11 is a schematic block diagram of the whole mechanism part of the apparatus.
This image forming apparatus is a line type image forming apparatus, has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided, a sheet 403 fed from the sheet feeding tray 404 is taken in, a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405, and then the side of the apparatus main body 401. The paper 403 is discharged to a paper discharge tray 406 attached to the printer.

  Also, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided, and when performing duplex printing, the sheet 403 is conveyed into the duplex unit 407 while being transported in the reverse direction by the transport mechanism 405 after one-side (front) printing is completed. Then, the other side (back side) is sent back to the transport mechanism 405 as the printable side, and the paper 403 is discharged to the paper discharge tray 406 after the other side (back side) printing is completed.

  Here, the image forming unit 402 is, for example, four full-line liquids according to the present invention that discharge droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y). The recording heads 411k, 411c, 411m, and 411y (which are referred to as “recording heads 411” when the colors are not distinguished) are configured with ejection heads, and each recording head 411 has a nozzle surface on which nozzles for ejecting droplets are formed downward. The head holder 413 is attached.

  In addition, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) is provided to maintain and recover the performance of the head corresponding to each recording head 411. During the head performance maintenance operation such as wiping processing, the recording head 411 and the maintenance / recovery mechanism 412 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 412 faces the nozzle surface of the recording head 411.

  Here, the recording head 411 is arranged to eject droplets of each color in the order of black, cyan, magenta, and yellow from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this. Further, as the line-type head, one or a plurality of heads provided with a plurality of nozzle rows for discharging droplets of each color at a predetermined interval can be used, and a recording liquid cartridge for supplying ink to the heads can be used. It can be integrated or separate.

  The paper 403 in the paper feed tray 404 is separated one by one by a paper feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401, and is registered along the guide surface 423 a of the transport guide member 423. It is sent between 425 and the conveyor belt 433, and is sent to the conveyor belt 433 of the conveyor mechanism 405 via the guide member 426 at a predetermined timing.

  In addition, the conveyance guide member 423 is also formed with a guide surface 423 b for guiding the paper 403 sent out from the duplex unit 407. Further, a guide member 427 for guiding the sheet 403 returned from the transport mechanism 405 to the duplex unit 407 during duplex printing is also provided.

  The conveyance mechanism 405 includes an endless conveyance belt 433 that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432, a charging roller 434 that charges the conveyance belt 433, and an image forming unit 402. A platen member 435 that maintains the flatness of the conveying belt 433 at the opposite portion, a pressing roller 436 that presses the paper 403 fed from the conveying belt 433 against the conveying roller 431 side, and other ink (not shown) that adheres to the conveying belt 433. It has a cleaning roller made of a porous body or the like as a cleaning means for removing.

  On the downstream side of the transport mechanism 405, a paper discharge roller 438 and a spur 439 for sending the paper 403 on which an image is recorded to the paper discharge tray 406 are provided.

  In the image forming apparatus configured as described above, the conveyance belt 433 moves in the direction indicated by the arrow, and is charged by contact with the charging roller 434 to which a high potential application voltage is applied. The conveyance belt is charged to this high potential. When the sheet 403 is fed onto the sheet 433, the sheet 403 is electrostatically attracted to the conveyance belt 433. In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface.

  Then, the paper 403 is moved around the conveyor belt 433 and droplets are ejected from the recording head 411, whereby a required image is formed on the paper 403, and the paper 403 on which the image has been recorded is the paper discharge roller 438. As a result, the paper is discharged to the paper discharge tray 406.

  As described above, since the image forming apparatus includes the recording head including the liquid discharge head according to the present invention, it is possible to perform highly reliable and stable droplet discharge and to form a high-quality image at high speed. can do.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. Further, the present invention can be applied to an image forming apparatus using a liquid other than the narrowly defined ink, a fixing processing liquid, or the like.

1 Channel plate (channel member)
2 Diaphragm member 2A First layer (surface layer; metal layer)
2B 2nd layer (intermediate layer; water repellent layer)
2C 3rd layer (surface layer; bonding layer; metal layer)
2a Vibration area (diaphragm part)
2b Island-shaped convex part 3 Nozzle plate 4 Nozzle 6 Liquid chamber 10 Common liquid chamber 12 Piezoelectric member 12A Drive piezoelectric element column 12B Non-drive piezoelectric element column 13 Base member 15 FPC (wiring member)
100 Piezoelectric actuator 233 Carriage 234a, 234b Recording head 411k, 411c, 411m, 411y Recording head

Claims (7)

A nozzle for discharging droplets;
A liquid chamber in communication with the nozzle;
And a rotation plate member vibration that form a part of the wall of the liquid chamber,
The part forming a part of the wall surface of the liquid chamber in the diaphragm member has a thin part and a thick part,
The thin portion of the diaphragm member has a structure of at least three layers,
A liquid discharge head, wherein an intermediate layer between surface layers on both sides is formed of a water repellent layer.   The liquid ejection head according to claim 1, wherein the intermediate layer is a perfluoropolyether having an alkoxysilane.   The liquid ejection head according to claim 1, wherein the intermediate layer is made of silicone.   The liquid ejection head according to claim 1, wherein the intermediate layer is a eutectoid plating film containing PTFE.   The surface layer opposite to the liquid chamber of the diaphragm member is a metal layer, and the intermediate layer has higher water repellency than the metal layer forming the surface layer opposite to the liquid chamber. Item 2. The liquid discharge head according to Item 1.   The surface layer on the liquid chamber side of the diaphragm member is a metal layer, and the intermediate layer has higher water repellency than the metal layer forming the surface layer on the liquid chamber side. Liquid discharge head.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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