JP6683946B2 - Liquid ejection head and liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection head and a liquid ejection device including the liquid ejection head.

  An image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, and a complex machine of these includes, for example, a liquid ejection head or a liquid ejection unit, and a device that drives the liquid ejection head to eject liquid (for example, inkjet recording Device) etc. are known.

  The liquid ejection head includes a nozzle for ejecting a liquid, a flow path plate provided with an individual liquid chamber for communicating with the nozzle to store the liquid, and a pressure generating unit (driving unit or energy) for pressurizing the liquid in the individual liquid chamber. Generating means) and a common liquid chamber substrate provided with a common liquid chamber for storing the liquid until it flows into the flow path plate, and the pressure generating means is driven to pressurize the ink in the individual liquid chamber, Ink droplets are ejected from the recording medium to land on the recording medium.

  Recently, an on-demand type liquid ejection head (inkjet head) configured to eject minute droplets of ink only when recording (printing) is required has become mainstream. In the on-demand liquid ejection head, as the pressure generating means, a piezoelectric element is used to deform the diaphragm forming the wall surface of the individual liquid chamber to eject the liquid, or a heating resistor is used to eject the liquid chamber. It is known that the liquid is heated to generate bubbles and the liquid is discharged by pressure.

  When the ink used in the inkjet head is an ink in which the solvent easily evaporates (for example, a water-soluble ink having a solid color pigment), the color pigment in the ink is evaporated by evaporation of the solvent during printing or during printing standby. There is a problem that the concentration increases and the viscosity increases.

  When the viscosity of the ink, which is the liquid to be ejected, increases, the fluid resistance when ejected from the nozzles increases, so that ejection failure such as a slow ejection speed of the droplets or the ejection failure occurs. As a result, the landing position deviation of the ink droplets on the recording medium occurs, which adversely affects the image quality. In addition, there is a problem in that the amount of ink to be discarded becomes large by performing idle discharge or suction in order to remove the ink in the liquid chamber whose viscosity has increased.

  It is known to perform ink circulation in order to make ink viscosity constant and improve ink ejection accuracy (see, for example, Patent Documents 1 and 2).

  In the ink circulation system, it is necessary to cool the ink on the head driver side while heating it to lower the ink temperature during circulation. In this case, it is required to reduce the output and quantity of the cooling and heating device and to improve the cooling efficiency and the heating efficiency. On the other hand, in Patent Document 1, a circulation flow path is provided in the vicinity of the nozzle, ink is supplied from the pressure chamber to the nozzle, and when the ink is ejected from the nozzle, a part of the ink is also flown in the circulation flow path. There has been proposed a configuration that suppresses an increase in ink viscosity due to circulation of ink.

  Further, in the circulation type droplet discharge head, since the flow paths are arranged in parallel, ink flow may occur in a direction opposite to the intended direction at the time of discharge or maintenance. On the other hand, in Patent Document 2, a circulation flow in which ink circulates around a pressure chamber is used as a droplet discharge head capable of generating a flow in a reverse direction during maintenance while preventing a reverse flow in normal circulation. By providing a passage, changing the shape of the connection passage connecting the pressure passage and the circulation passage between the circulation passage and the pressure chamber, and utilizing the fluid resistance generated by the shape change, from the circulation passage to the pressure chamber, A configuration has been proposed in which ink flows from the pressure chamber to the circulation channel.

  However, the configurations described in Patent Document 1 and Patent Document 2 require a means (for example, a pump) for causing the ink in the circulation channel to flow. In addition, since the movement of ink from the circulation channel to the pressure chamber and the movement of ink from the pressure chamber to the circulation channel depend on the pressure element of the pressure chamber, if ink is not ejected from the nozzle, Since the solvent is evaporated and the ink viscosity in the nozzle increases, there is a problem that the ink ejection speed from the nozzle becomes slow when printing is restarted and the image quality deteriorates.

  Therefore, according to the present invention, it is possible to reliably circulate the liquid to be ejected both during liquid ejection and during ejection standby, prevent an increase in viscosity of the liquid, and suppress a decrease in liquid ejection speed or ejection accuracy. An object of the present invention is to provide a simple liquid ejection head.

In order to achieve such an object, a liquid ejection head according to the present invention has a nozzle plate having a plurality of nozzles for ejecting a liquid, one end communicating with the nozzle via a communication pipe, and the other end communicating with a common liquid chamber. A flow path plate that forms an individual liquid chamber, a communication tube plate that forms the communication pipe, a vibration plate that forms at least a part of the wall surface of the individual liquid chamber, and a first that transmits pressure fluctuations to the vibration plate. In the liquid discharge head including the pressure generating means of (1), a circulation channel for collecting and circulating a part of the liquid supplied to the nozzle is provided, and the liquid remaining in the communication pipe flows into the circulation channel. And an individual circulation channel that collects the liquid in the individual circulation channel, and the individual circulation channel has a cross-sectional area of the channel toward the connection portion with the common circulation channel. It has an enlarged cross-sectional area and Comprising a second pressure generating means for transmitting a pressure variation in a member constituting at least a part of the wall area, said the circulation flow path plate to form the circulation flow path and the nozzle plate is bonded, said cross-sectional enlarged region Is a liquid discharge head characterized in that at least a part of its wall surface is constituted by the nozzle plate, and the second pressure generating means is provided on the nozzle plate .

  According to the present invention, it is possible to reliably circulate the liquid to be ejected both during liquid ejection and during ejection standby, prevent increase in the viscosity of the liquid, and suppress deterioration of the liquid ejection speed and ejection accuracy. It is possible to provide a possible liquid ejection head.

It is a perspective view which shows typically the state which decomposed | disassembled the liquid discharge head of this invention. It is a sectional view showing an example of a liquid discharge head of the present invention. It is a partially expanded view of a circulation channel plate. FIG. 3 is a partially enlarged view of a cross section showing an example of the liquid ejection head of the present invention. FIG. 3 is a partially enlarged view of a cross section showing an example of the liquid ejection head of the present invention. FIG. 3 is a partially enlarged view of a cross section showing an example of the liquid ejection head of the present invention. FIG. 1 is a schematic diagram of an inkjet image forming apparatus that is one embodiment of a liquid ejection apparatus according to the present invention. It is a graph which shows the relationship between a cross-sectional area ratio and a fluid resistance coefficient.

  Hereinafter, a liquid ejection head and a liquid ejection device according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions and the like can be modified within the scope that those skilled in the art can contemplate, and any mode Also in the above, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

[Liquid ejection head]
In the present application, a “liquid ejection head” is a functional component that ejects and ejects liquid from a nozzle.
The liquid to be ejected is not particularly limited as long as it has a viscosity and a surface tension that can be ejected from the head, but it is one that has a viscosity of 30 mPa · s or less at room temperature and atmospheric pressure, or by heating and cooling. It is preferable. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins and calcium. , Solutions, suspensions, emulsions containing edible materials such as natural pigments, etc., such as ink-jet inks, surface treatment solutions, components of electronic devices and light-emitting devices, and formation of electronic circuit resist patterns. It can be used for applications such as a working fluid and a three-dimensional modeling material fluid.

  Piezoelectric actuators (multilayer piezoelectric element and thin film piezoelectric element), thermal actuators that use electrothermal conversion elements such as heating resistors, electrostatic actuators that consist of a diaphragm and counter electrode, etc. are used as the energy generation source that ejects liquid What you do is included.

Further, in the terms of the present application, image forming, recording, printing, printing, printing, modeling, etc. are synonymous.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view schematically showing a state where the liquid ejection head of the present invention is disassembled. 2 is a sectional view taken along the line AA shown in FIG. 1, and FIG. 3 is a partially enlarged view of the circulation flow channel plate 2 forming a circulation flow channel.

The liquid ejection head of the present embodiment has a nozzle plate 1 having a plurality of nozzles 10 for ejecting liquid, an individual liquid chamber in which one end communicates with the nozzle 10 via a communication pipe 15 and the other end communicates with a common liquid chamber 12. A flow path plate 4 that forms the communication pipe 11, a communication pipe plate 3 that forms the communication pipe 15, a vibration plate 5 that forms at least a part of the wall surface of the individual liquid chamber 11, and a vibration plate 5 that transmits pressure fluctuations. One pressure generating means 6 is provided.
In the present embodiment, a description will be given based on an aspect including a piezoelectric element (piezoelectric actuator) as the first pressure generating means 6.

  The liquid ejection head of this embodiment includes a piezoelectric element support member 7, a common liquid chamber forming member 8, and a head protection member 9, and the first pressure generating means (ejection piezoelectric element) 6 has a first A first flexible substrate (ejection FPC) 14 on which a drive circuit (ejection drive circuit) 13 is mounted is connected. The first flexible substrate 14 is formed of a thin film member that is flexible and can be largely deformed, and has a plurality of electric paths on its inner surface.

The liquid ejection head of the present embodiment further has a circulation flow path for collecting and circulating a part of the liquid supplied to the nozzle 10, and the circulation flow path is an individual flow path through which the liquid remaining in the communication pipe flows. It is composed of a circulation flow channel 21 and a common circulation flow channel 22 that collects the liquid in the individual circulation flow channel, and the individual circulation flow channel 21 has a cross-sectional area of the flow channel that increases toward the connection portion with the common circulation flow channel 22. The second pressure generating means 30 having the enlarged cross-sectional area 27 and transmitting the pressure fluctuation to the member forming the wall surface of at least a part of the enlarged cross-sectional area 27 is provided.
In the present embodiment, a description will be given based on a mode in which a piezoelectric element (piezoelectric actuator) is provided as the second pressure generating means 30.

In the example shown in FIG. 2, the second pressure generating means (piezoelectric element for circulation) 30 is provided in a region constituting the wall surface of the enlarged cross-sectional region 27 of the nozzle plate 1. The circulation piezoelectric element 30 includes a circulation piezoelectric body 20, a circulation upper electrode 25, and a circulation lower electrode 26.
As the circulating piezoelectric body 20 that constitutes the circulating piezoelectric element 30, a thin film PZT that can reduce the thickness is preferable.
A second flexible substrate (circulation FPC) 24 on which a second drive circuit (circulation drive circuit) 23 is mounted is connected to the circulation piezoelectric element 30. The second flexible substrate 24 is formed of a thin film member that is flexible and can be greatly deformed, and has a plurality of electric paths on its inner surface.

Hereinafter, a case where the ejected liquid is ink will be described.
During printing, the ejected ink is supplied from the ink tank to each individual liquid chamber 11 through the ejection common liquid chamber 12a. The ink in the individual liquid chamber 11 is ejected to the outside from the nozzle 10 through the communication pipe 15 by the pressure generated by the displacement of the ejection piezoelectric element 6.
On the other hand, a part of the ink remaining in the communication pipe 15 without being discharged from the nozzle 10 flows into the individual circulation flow passage 21, passes through the enlarged cross-sectional area 27, and then flows from the common circulation flow passage 22 to the circulation common liquid chamber. It flows to 12b. The ink that has flowed into the circulation common liquid chamber 12b is supplied again for ejection.

As described above, in the flow path between the individual circulation flow path 21 and the common circulation flow path 22, when the ejection piezoelectric element 6 operates during printing, the ink flow from the individual circulation flow path 21 to the enlarged cross-sectional area 27. Occurs.
On the other hand, during printing standby, the piezoelectric element 30 for circulation operates to generate a pressure change in the cross-sectional enlarged region 27 of the individual circulation flow channel 21, and as a result, the ink in the cross-sectional enlarged region 27 communicates with the individual circulation flow channel 21. A flow in the direction of the pipe 15 and a flow in the direction of the common circulation channel 22 occur.
Since the cross-sectional area of the individual circulation flow passage 21 on the side of the communication pipe 15 is smaller than that of the enlarged cross-sectional area 27, the fluid resistance becomes large, whereas the common circulation passage 22 has a larger cross-sectional area than that of the enlarged cross-sectional area 27. Fluid resistance decreases. Therefore, the ink in the enlarged cross-sectional area 27 flows in the direction of the common circulation flow path 22, and it is possible to prevent erroneous ejection from the nozzle 10 due to the drive of the circulation piezoelectric element 30.

As described above, the fluid resistance is high from the expanded cross-sectional area 27 to the individual circulation flow path 21, ink hardly flows, and the fluid resistance is low from the expanded circulation area 21 to the expanded cross-section area 27, and the ink easily flows. preferable.
In the flow path having the shape as shown in FIG. 3, the fluid resistance when the ink flows from the individual circulation flow path 21 to the enlarged cross section area 27 (the fluid resistance of the sudden expansion tube) and the individual circulation flow path 21 from the enlarged cross section area 27. All of these conditions can be satisfied by setting the cross-sectional area ratio so that the fluid resistance when the ink flows (the fluid resistance of the rapid reduction tube) becomes constant.
FIG. 8 is a graph showing the relationship between the cross-sectional area ratio and the fluid resistance coefficient in the sudden contraction tube and the sudden expansion tube. As shown in FIG. 8, it is preferable that the ratio of the cross-sectional area of the individual circulation flow passage 21 to the cross-sectional area of the cross-sectional enlarged region 27 is 0.5.

  In addition, it is preferable that the enlargement ratio of the cross-sectional area in the cross-sectional enlarged region 27 of the individual circulation flow passage 21 is larger than the enlargement ratio of the cross-sectional area of the common circulation passage 22 in the cross-sectional enlarged region 27.

According to the liquid ejection head of the present embodiment, the common liquid chamber 12b, the individual liquid chamber 11, the communication pipe 15, the individual circulation flow path 21, and the enlarged cross-sectional area 27 can be provided without a circulation pump for circulating ink. Then, the ink can be circulated to the common circulation channel 22.
In addition, the ejected ink can be reliably circulated during the liquid ejection and the ejection standby, the increase in the viscosity of the ink can be prevented, and the decrease in the ink ejection speed and the ejection accuracy can be suppressed. .

(Second embodiment)
The liquid ejection head of this embodiment will be described with reference to FIG. FIG. 4 corresponds to a cross-sectional view taken along the line AA shown in FIG.
As shown in FIG. 4, in the liquid ejection head of the present embodiment, the circulation flow channel plate 2 forming the circulation flow channel and the nozzle plate 1 are joined, and at least a part of the wall surface of the enlarged cross-sectional area 27 has the nozzle plate 1. The second pressure generating means 30 is provided on the nozzle plate 1.
The nozzle plate 1 has a thin portion 28 at least in a region forming the wall surface of the cross-sectional enlarged region 27 of the individual circulation flow passage 21, and the thin portion 28 is provided with the second pressure generating means 30.

Since the circulation piezoelectric element 30 is provided in the thin portion 28 of the nozzle plate 1 having the reduced thickness, the circulation piezoelectric element 30 is provided as compared with the case where the circulation piezoelectric element 30 is provided in the nozzle plate having the reduced thickness (for example, the example of FIG. 2). The displacement by the element 30 becomes large.
As a result, the pressure generated in the enlarged cross-sectional area 27 increases, the flow rate from the individual circulation flow path 21 to the common circulation flow path 22 increases, and the ink circulation efficiency can be improved.

(Third embodiment)
The liquid ejection head of this embodiment will be described with reference to FIG. FIG. 5 corresponds to a cross-sectional view taken along the line AA shown in FIG.
As shown in FIG. 5, in the liquid ejection head of this embodiment, an elastic plate 29 that is elastically deformable is joined to one surface of the circulation flow channel plate 2 that forms a circulation flow channel, and at least one of the enlarged cross-sectional areas 27 is formed. The wall surface of the part is constituted by an elastic plate 29. The second pressure generating means 30 is provided on the elastic plate 29.

Since the nozzle plate 1 and the elastic plate 29 are separate members, a material (type, thickness) suitable for transmitting the displacement from the circulation piezoelectric element 30 to the enlarged sectional area 27 as the elastic plate 29 should be appropriately selected. You can
As a result, since the pressure generated in the enlarged cross-sectional area 27 can be maximized, the flow rate from the individual circulation flow passage 21 to the common circulation flow passage 22 increases, and the ink circulation efficiency can be improved.

(Fourth embodiment)
The liquid ejection head of this embodiment will be described with reference to FIG. FIG. 6 corresponds to a cross-sectional view taken along the line AA shown in FIG.
As shown in FIG. 6, in the liquid ejection head of this embodiment, an elastic plate 29 is provided between the circulation flow path plate 2 and the communication tube plate 3 and faces the nozzle plate 1 in the enlarged cross-sectional area 27. The wall surface is constituted by the elastic plate 29. The second pressure generating means 30 is provided on the elastic plate 29.

  Since the circulation piezoelectric element 30 is arranged inside the liquid ejection head body, it is protected from an external impact. Further, the gap between the nozzle 10 and the medium can be shortened as compared with the other embodiment in which the circulation piezoelectric element 30 is arranged so as to project outside the nozzle plate 1.

In any of the above embodiments, the direction of deformation by the pressure generating means can be set as appropriate.
The direction in which the cross-sectional enlarged region 27 of the individual circulation flow passage 21 is deformed by the second pressure generating means 30 and the direction in which the individual liquid chamber 11 is deformed by the first pressure generating means 6 may be opposite. The direction in which the cross-sectional enlarged region 27 of the individual circulation flow passage 21 is deformed by the second pressure generating means 30 and the direction in which the individual liquid chamber 11 is deformed by the first pressure generating means 6 may be the same direction.

[Liquid discharge device]
A liquid ejection apparatus according to the present invention is an apparatus for ejecting a liquid, and includes the liquid ejection head of the present invention. Hereinafter, a liquid ejection apparatus equipped with the liquid ejection head of the present invention will be described with reference to FIG.

  In the present application, the “device that ejects liquid” is a device that includes a liquid ejection head or a liquid ejection unit and that drives the liquid ejection head to eject liquid. The device for ejecting a liquid includes not only a device capable of ejecting a liquid to which a liquid can be attached, but also a device ejecting the liquid toward the air or into the liquid.

This "device for ejecting liquid" may include a means for feeding, carrying, and discharging paper to which liquid can be attached, as well as a pretreatment device, a posttreatment device, and the like.

For example, as an "apparatus for ejecting liquid", an image forming apparatus which is an apparatus for ejecting ink to form an image on a sheet, and for forming a three-dimensional object (three-dimensional object), powder is formed in layers. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges a modeling liquid to the powder layer.

  Further, the “apparatus for ejecting liquid” is not limited to one in which a significant image such as characters and figures is visualized by the ejected liquid. For example, it also includes those that form a pattern or the like that has no meaning per se, and those that form a three-dimensional image.

  The above-mentioned "liquid can be adhered" means a liquid which can be at least temporarily adhered, and which adheres and fixes, adheres and permeates, and the like. Specific examples include recording media such as paper, recording paper, recording paper, film and cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, inspection cells and other media. Yes, and unless otherwise specified, includes anything to which liquid adheres.

  The material of the above "material to which liquid can be adhered" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, etc. as long as liquid can be adhered to it even temporarily.

  The “liquid” may be any one that has a viscosity and a surface tension that can be ejected from the head, and is not particularly limited, but it is one that has a viscosity of 30 mPa · s or less at room temperature, atmospheric pressure, or by heating or cooling. Preferably there is. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium. , Solutions, suspensions, emulsions containing edible materials such as natural pigments, etc., such as ink-jet inks, surface treatment solutions, components of electronic devices and light-emitting devices, and formation of electronic circuit resist patterns. It can be used for applications such as a working fluid and a three-dimensional modeling material fluid.

  Further, the “device for ejecting liquid” includes a device in which the liquid ejection head and the device to which the liquid can be attached move relatively, but the device is not limited to this. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

  In addition, as the "apparatus for ejecting the liquid", a treatment liquid application device for ejecting the treatment liquid onto 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, etc. There is an injection granulating device which granulates the fine particles of the raw material by spraying a composition liquid in which is dispersed in a solution through a nozzle.

  Further, in the terms of the present application, image forming, recording, printing, printing, printing, modeling, etc. are synonymous.

FIGS. 7A and 7B illustrate an inkjet image forming apparatus, which is a liquid discharging apparatus in which the liquid discharging head of the present invention is mounted as an inkjet head, as an example.
FIGS. 7A and 7B are views showing an inkjet image forming apparatus 301 which is a liquid ejecting apparatus equipped with a liquid ejecting unit including a liquid ejecting head (inkjet head), and FIG. Is a perspective view showing the outline of FIG.

  The “liquid ejection unit” is a unit in which functional components and mechanisms are integrated with a liquid ejection head, and is a collection of components related to liquid ejection. For example, the “liquid ejection unit” includes a combination of at least one of the supply / circulation mechanism, the carriage, the maintenance / recovery mechanism, and the main scanning movement mechanism with the liquid ejection head.

  Here, the term “integrated” means, for example, a liquid discharge head, a functional component, and a mechanism that are fixed to each other by fastening, bonding, engaging, or the like, or one that is movably held with respect to the other. Including. Further, the liquid ejection head, the functional component, and the mechanism may be configured to be detachable from each other.

For example, as a liquid ejection unit, there is one in which a liquid ejection head and a supply / circulation mechanism are integrated. In addition, there is one in which a liquid ejection head and a supply / circulation mechanism are integrated by being connected to each other by a tube or the like. Here, it is also possible to add a unit including a filter between the supply / circulation mechanism of these liquid ejection units and the liquid ejection head.
Further, as a liquid ejection unit, there is one in which a liquid ejection head and a carriage are integrated.

  Further, as a liquid ejection unit, there is a unit in which a liquid ejection head and a scanning movement mechanism are integrated so that a liquid ejection head is movably held by a guide member that constitutes a part of the scanning movement mechanism.

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

  Further, as a liquid ejection unit, there is one in which a tube is connected to a liquid ejection head to which a supply / circulation mechanism or a flow path component is attached, and the liquid ejection head and the supply mechanism are integrated. The liquid from the liquid storage source is supplied to the liquid ejection head via this tube.

  The main scanning moving mechanism includes a single guide member. The supply mechanism also includes a tube unit and a loading unit unit.

  The inkjet image forming apparatus 301 is a liquid discharge device including a carriage movable in the main scanning direction, a recording head including an inkjet head mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like inside the apparatus main body. The unit is housed in the printing mechanism unit 302. A paper feed cassette (paper feed tray) 304 capable of stacking a large number of recording papers 303 can be detachably attached to the lower part of the apparatus main body from the front side, and the recording papers 303 are manually fed. The manual feed tray 305 can be opened and closed, the recording paper 303 fed from the paper feed cassette 304 or the manual feed tray 305 is taken in, the desired image is recorded by the print mechanism unit 302, and then the manual feed tray 305 is mounted on the rear surface side. The sheet is discharged to the discharge tray 306.

  The printing mechanism unit 302 holds a carriage 313 slidably in the main scanning direction (perpendicular to the paper surface) by a main guide rod 311 and a sub guide rod 312, which are guide members that are horizontally mounted on left and right side plates (not shown), On the carriage 313, a recording head 314 including an ink jet head that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (B) is provided with a plurality of ink ejection ports in the main scanning direction. They are arranged in a crossing direction, and are mounted with the ink droplet ejection direction facing downward. Further, each ink cartridge 315 for supplying each color ink to the recording head 314 is replaceably mounted on the carriage 313.

  The ink cartridge 315 has an air port that communicates with the atmosphere above, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body is used. The ink supplied to the inkjet head is maintained at a slight negative pressure.

  Further, although the recording heads 314 for the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets for the respective colors may be used. Further, the ink jet head used as the recording head 314 ejects ink by generating bubbles by a piezo type in which ink is pressed through a vibrating plate forming a wall surface of a liquid chamber by an electromechanical conversion element such as a piezoelectric element or by a heating resistor. A bubble type that pressurizes, or an electrostatic type that presses ink by displacing the vibrating plate by an electrostatic force between the vibrating plate forming the wall surface of the ink flow path and an electrode facing the vibrating plate can be used. In this embodiment, an electrostatic inkjet head is used.

  Here, the carriage 313 is slidably fitted to the main guide rod 311 on the rear side (downstream side in the sheet conveying direction) and slidably mounted on the sub guide rod 312 on the front side (downstream side in the sheet conveying direction). is doing. Then, in order to move and scan the carriage 313 in the main scanning direction, a timing belt 320 is stretched between a drive pulley 318 and a driven pulley 319 which are rotationally driven by a main scanning motor 317, and the timing belt 320 is attached to the carriage 313. The carriage 313 is reciprocally driven by forward and reverse rotations of the main scanning motor 317.

  On the other hand, in order to convey the recording paper 303 set in the paper feeding cassette 304 to the lower side of the recording head 314, a paper feeding roller 321 and a friction pad 322 for separately feeding the recording paper 303 from the paper feeding cassette 304, and a recording paper. A guide member 323 that guides 303, a conveyance roller 324 that reverses and conveys the fed recording paper 303, a conveyance roller 325 that is pressed against the peripheral surface of the conveyance roller 324, and the recording paper 303 from the conveyance roller 324. A leading end roller 326 is provided for defining the delivery angle. The transport roller 324 is rotationally driven by the sub-scanning motor 327 via a gear train.

  Further, a print receiving member 329 that is a paper guide member that guides the recording paper 303 sent out from the transport roller 324 below the recording head 314 in correspondence with the movement range of the carriage 313 in the main scanning direction is provided. A transport roller 331 and a spur 332 that are driven to rotate in order to send out the recording paper 303 in the paper discharge direction are provided on the downstream side of the print receiving member 329 in the paper transport direction, and the recording paper 303 is further sent to the paper discharge tray 306. A paper discharge roller 333, a spur 334, and guide members 335 and 336 forming a paper discharge path are arranged.

  At the time of recording, the recording head 314 is driven according to an image signal while moving the carriage 313, so that ink is ejected onto the recording sheet 303 which is stopped to record one line, and the recording sheet 303 is conveyed by a predetermined amount. Then record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the recording paper 303 reaches the recording area, the recording operation is ended and the recording paper 303 is ejected.

  A recovery device 337 for recovering the ejection failure of the recording head 314 is arranged at a position outside the recording area on the right end side of the carriage 313 in the moving direction. The recovery device has a cap means, a suction means, and a cleaning means. The carriage 313 is moved to the recovery device 337 side during printing standby, the recording head 314 is capped by the capping means, and the ejection port portion is kept wet to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant, and stable ejection performance is maintained.

  When an ejection failure occurs, the ejection port of the recording head 314 is sealed by a capping unit, and air bubbles and the like are sucked out from the ejection port by a suction unit through a tube and ink or dust adhered to the ejection port surface is cleaned. And the defective ejection is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Circulation flow path plate 3 Communication tube plate 4 Flow path plate 5 Vibration plate 6 First pressure generating means (discharge piezoelectric element)
7 Piezoelectric element support member 8 Common liquid chamber forming member 9 Head protection member 10 Nozzle 11 Pressure chamber 12 Common liquid chamber 12a Discharge common liquid chamber 12b Circulation common liquid chamber 13 First drive circuit (discharge drive circuit)
14 First flexible substrate (Discharge FPC)
15 Communication Pipe 20 Circulation Piezoelectric Body 21 Individual Circulation Flow Path 22 Common Circulation Flow Path 23 Second Drive Circuit (Circulation Drive Circuit)
24 Second flexible board (FPC for circulation)
25 Circulating Lower Electrode 26 Circulating Upper Electrode 27 Cross Section Expanded Area 28 Thin Wall 29 Elastic Plate 30 Second Pressure Generating Means (Circulating Piezoelectric Element)
301 Liquid ejecting apparatus (inkjet image forming apparatus)
313 carriage 314 recording head 315 ink cartridge

JP, 2009-241316, A Japanese Patent No. 5495385

Claims (6)

A nozzle plate having a plurality of nozzles for ejecting liquid,
A flow path plate having one end communicating with the nozzle via a communication pipe and the other end forming an individual liquid chamber communicating with the common liquid chamber;
A communication tube plate forming the communication tube;
A diaphragm that forms at least a part of the wall surface of the individual liquid chamber,
A first pressure generating means for transmitting pressure fluctuations to the vibrating plate;
A circulation channel is provided for collecting and circulating a part of the liquid supplied to the nozzle,
The circulation channel is composed of an individual circulation channel into which the liquid remaining in the communication pipe flows, and a common circulation channel that collects the liquid in the individual circulation channel, and the individual circulation channel is the common circulation channel. Second pressure generating means for transmitting a pressure fluctuation to a member forming a wall surface of at least a part of the cross-sectional enlarged area, which has a cross-sectional enlarged area in which the cross-sectional area of the flow channel is enlarged toward a connecting portion with the flow passage. Equipped with
The circulation flow path plate forming the circulation flow path and the nozzle plate are joined, and at least a part of the wall surface of the enlarged cross-sectional area is formed of the nozzle plate,
It said second pressure generating means, the liquid discharge head you characterized in that provided in the nozzle plate. The nozzle plate has a thin portion at least in a region forming a wall surface of the enlarged cross-sectional region of the individual circulation passage, and the second pressure generating means is provided in the thin portion. The liquid ejection head according to claim 1 . A nozzle plate having a plurality of nozzles for ejecting liquid,
A flow path plate having one end communicating with the nozzle via a communication pipe and the other end forming an individual liquid chamber communicating with the common liquid chamber;
A communication tube plate forming the communication tube;
A diaphragm that forms at least a part of the wall surface of the individual liquid chamber,
A first pressure generating means for transmitting pressure fluctuations to the vibrating plate;
A circulation channel is provided for collecting and circulating a part of the liquid supplied to the nozzle,
The circulation channel is composed of an individual circulation channel into which the liquid remaining in the communication pipe flows, and a common circulation channel that collects the liquid in the individual circulation channel, and the individual circulation channel is the common circulation channel. Second pressure generating means for transmitting a pressure fluctuation to a member forming a wall surface of at least a part of the cross-sectional enlarged area, which has a cross-sectional enlarged area in which the cross-sectional area of the flow channel is enlarged toward a connecting portion with the flow passage. Equipped with
An elastically deformable elastic plate is joined to one surface of the circulation flow path plate forming the circulation flow path, and at least a part of the wall surface of the enlarged cross-sectional area is formed of the elastic plate,
Said second pressure generating means, the liquid discharge head you characterized in that provided on the elastic plate. The direction in which the cross-sectional enlarged region of the individual circulation flow path is deformed by the second pressure generating means and the direction in which the individual liquid chamber is deformed by the first pressure generating means are opposite directions. liquid discharge head according to any one of claims 1 to 3. The direction in which the cross-sectional enlarged region of the individual circulation flow path is deformed by the second pressure generating means and the direction in which the individual liquid chamber is deformed by the first pressure generating means are the same direction. liquid discharge head according to any one of claims 1 to 3. A liquid ejection apparatus comprising the liquid ejection head according to any one of claims 1 to 5.