JP2011056924A - Liquid jet head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a high effect in suppressing pressure wave cannot be obtained, by reducing the area of a damper region forming part of the wall of a common liquid chamber. <P>SOLUTION: Part of the wall of the common liquid chamber 8 is formed from a vibration plate member 2. Further, a deformable regional part (damper region) 20 formed from only the first layer 2a of the vibration plate member 2 is provided. The damper region 20 has a flat region 21 and a plurality of bending regions 22 provided in the lengthwise direction of the damper region 20 across the flat region 21. The bending regions 22 are arranged in parallel to each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejection head and an image forming apparatus, and more particularly to a liquid ejection head that ejects liquid droplets and an image forming apparatus including the head.

  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. As an apparatus, an ink jet recording apparatus or the like is 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.

  The liquid discharge head includes a nozzle that discharges droplets, an individual liquid chamber (also referred to as a pressurized liquid chamber, a discharge chamber, a pressure chamber, and a liquid flow path) that communicates with the nozzle, and liquid in the pressure chamber. A pressure generating means (energy generating means) for generating pressure (energy) to be pressurized and a common liquid chamber having a relatively large volume for supplying a liquid to each pressure chamber; A liquid droplet is ejected from the nozzle by pressurizing the liquid. Here, as the pressure generating means, a thermal method using a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, a piezoelectric device (in this application, it is used as a synonym for an electromechanical transducer). There are known a piezoelectric method using an electrostatic method, an electrostatic method using an electrostatic actuator that generates an electrostatic force, and the like.

  In recent years, downsizing and higher performance have been demanded for this image forming apparatus as its application has been expanded. More specifically, high performance means that image formation is performed at high speed, droplet size, flight speed, and the like are controlled more precisely to obtain a high-quality image. Both the number and density of nozzles tend to increase in response to the demands for miniaturization and high speed. Along with this, the intervals between the pressurized liquid chambers are narrowed, and the driving frequency for applying the discharge energy tends to be high for speeding up.

  In such a liquid discharge head that is required to have a large number of high-density nozzles, pressure waves are generated in the liquid in the pressurized liquid chamber by the discharge energy applied to the predetermined pressurized liquid chamber. At the same time, the pressure fluctuation generated in the pressurized liquid chamber becomes a pressure wave and propagates to a common flow path (hereinafter referred to as “common liquid chamber”) that supplies the liquid to the plurality of pressurized liquid chambers.

  When the pressure wave propagated to the common liquid chamber propagates back to the pressurized liquid chamber that discharges the liquid droplet, the pressure of the pressurized liquid chamber is changed, and the meniscus cannot be controlled. Droplets cannot be ejected with the amount of droplets (drop volume), which may cause non-ejection of droplets. In addition, if the pressure wave propagated to the common liquid chamber propagates to the adjacent pressurized liquid chamber and causes mutual interference that affects the liquid, liquid droplets are unintentionally leaked, discharged, and unstable in discharge state. Will be triggered. As a result, obtaining a high-quality image output is hindered. Furthermore, this tendency becomes more prominent as the driving frequency of the liquid discharge head increases, and the image quality deteriorates. These phenomena hindered high density and high drive frequency of the nozzles of the liquid discharge head.

  Therefore, as a means for preventing discharge abnormality due to the propagation of the pressure wave, it is common to suppress the pressure wave by providing a damper having a large acoustic compliance in a part of the wall constituting the common liquid chamber. Has been done. To increase the damper's ability to suppress pressure waves, it is effective to increase the area of the damper. However, increasing the size of the damper leads to an increase in the size of the head.

  For this reason, there is a need for a method of increasing compliance while avoiding an increase in the size of the damper. For example, a part of the partition wall that defines the common ink chamber is configured to be thinner than the other parts, so that the nozzle row direction A long diaphragm portion is formed, and an island-shaped beam portion long in the nozzle row direction is formed on the surface of the diaphragm portion (Patent Document 1).

  Further, it is also known that the elastic film that seals one opening surface of the common ink chamber has a portion formed by plastic deformation due to an external force at a portion that seals one opening surface of the common ink chamber. (Patent Document 2).

JP 2008-173787 A Japanese Patent No. 3620293

  However, in the configuration of Patent Document 1, when a part of the damper is thinned, if it is too thin, fine holes are likely to be generated in the film due to the non-uniformity of the film thickness at the time of manufacture. There is a problem that the yield rate is increased. Although the compliance of the damper is expected to be further increased, the thickness of the damper is currently reduced to a range below 5 μm in the case of metal, for example, and there is a limit to further thinning.

  Moreover, according to the structure of patent document 2, the objective of making small the tension | tensile_strength generate | occur | produced by the thermal contraction of the damper material in a manufacturing process and enlarging a damper can be achieved certainly. However, the configuration disclosed in Patent Document 2 is effective only in a configuration that is manufactured by a combination of a specific material and a manufacturing method and tension is generated in the damper portion in the manufacturing process.

  This point will be described in detail. When the manufactured head does not generate tension, for example, no heat treatment is performed, or a damper is formed of a material having a small linear expansion coefficient such as metal, an effect can be obtained. Absent. Further, even if the configuration described in Patent Document 2 is applied, since the inside of the head is always a negative pressure both when driven and when not driven, in a configuration where the entire damper is simply bent, the formed bent portion is It always remains extended toward the liquid flow path inside the head. Therefore, when the damper expands and contracts in order to fulfill its function, the damper expands and contracts while receiving a tension in the direction that inhibits displacement from the four directions, like a flat damper without bending. That is, the tension generated before the planar damper is displaced approaches 0, but the tension generated in the direction of inhibiting the displacement when the damper is displaced cannot be reduced.

  The present invention has been made in view of the above problems, and an object thereof is to obtain a larger pressure wave absorption effect in a small area.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A plurality of nozzles for discharging droplets;
An individual flow path through which the nozzle communicates;
A common liquid chamber for supplying liquid to each individual flow path,
A deformable region portion is provided in a part of the member forming the wall surface of the common liquid chamber,
The deformable region portion has a planar region and a plurality of bending regions across the planar region,
The bending regions are arranged in parallel to each other.

  Here, the bending region may be configured to be provided adjacent to a boundary where the deformable region portion is in contact with the non-deformable region portion.

  Further, the plurality of bending regions may be provided along the nozzle arrangement direction.

  Further, the deformable region portion may be configured such that the area of the planar region is larger than the areas of the plurality of bending regions.

  In addition, the deformable region portion may be configured such that two bending regions are provided on both sides of the one planar region.

  Further, the member forming the wall surface of the common liquid chamber may be a diaphragm member having a multilayer structure, and the deformable region portion may be formed by a part of the layer of the diaphragm member.

  An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

  According to the liquid ejection head according to the present invention, the deformable region portion is provided in a part of the member forming the wall surface of the common liquid chamber, and the deformable region portion includes a planar region and a plurality of regions sandwiching the planar region. Therefore, a larger pressure wave absorption effect can be obtained with a smaller area.

  The image forming apparatus according to the present invention includes the liquid ejection head according to the present invention, so that the droplet ejection performance is stable, and stable image ejection can be performed to form a high-quality image.

FIG. 3 is an explanatory plan view of the first embodiment of the liquid ejection head according to the present invention as viewed from the nozzle direction. FIG. 2 is a cross-sectional explanatory view taken along line AA in FIG. 1. FIG. 3 is a cross-sectional explanatory view taken along line BB in FIG. 2. It is explanatory drawing of one damper area | region. It is explanatory drawing explaining the deformation | transformation state of X1-X1 vicinity of FIG. It is explanatory drawing explaining the deformation | transformation state of X2-X2 vicinity of FIG. 4 similarly. FIG. 10 is an explanatory diagram for explaining a damper region of Comparative Example 1; FIG. 10 is an explanatory diagram for explaining a damper region of Comparative Example 2; It is a plane explanatory view of one damper field for explanation of a 2nd embodiment of the liquid discharge head concerning the present invention. It is a plane explanatory view of one damper area for explanation of a third embodiment of the liquid ejection head according to the present invention. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. 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. First, a first embodiment of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an explanatory plan view of the liquid discharge head as viewed from the nozzle direction, FIG. 2 is an explanatory sectional view taken along line AA in FIG. 1, and FIG. 3 is an explanatory sectional view taken along line BB in FIG. It is.

  The liquid discharge head includes a flow path member (flow path plate, liquid chamber substrate) 1, a vibration plate member 2 bonded to the lower surface of the flow path member 1, and a nozzle plate 3 bonded to the upper surface of the flow path member 1. Thus, an individual flow path (hereinafter also referred to as a “pressurized liquid chamber”) 6 through which a nozzle 4 for discharging a droplet (liquid droplet) communicates via a communication path 5 is formed. A common liquid chamber 8 for supplying ink, which is liquid, via the communication portion 9 provided in the diaphragm member 2 to the liquid chamber 6, the communication passage 10 formed in the flow path member 1, and the fluid resistance portion 7 is a frame member 17 described later. Is formed.

  Here, the flow path member 1 is formed by anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110) using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), thereby allowing each pressurized liquid chamber 6 or Openings and grooves such as the fluid resistance portion 7 and the communication passage 10 are formed. In addition, the flow path member 1 can also form each pressurization liquid chamber 6 etc. by carrying out mechanical processing, such as etching or punching, using an acidic etching liquid, and the flow path member 1 can also be formed. 1 and the nozzle plate 3 or the diaphragm member 2 can be integrally formed by electroforming. Other photosensitive resins can also be used.

  The diaphragm member 2 is formed of a nickel plate having a three-layer structure of the first layer 2a, the second layer 2b, and the third layer 2c from the pressurized liquid chamber 6 side, and is manufactured by electroforming, for example. As the diaphragm member 2, for example, a laminated member of a resin member such as polyimide and a metal plate such as a SUS substrate, or a member formed from a resin member can be used.

  The nozzle plate 3 forms a large number of nozzles 4 corresponding to the pressurized liquid chambers 6 and is bonded to the flow path member 1 with an adhesive. As this nozzle plate 3, what consists of metals, such as stainless steel and nickel, resin, such as a polyimide resin film, silicon | silicone, and those combinations can be used. Further, the inner shape (inner shape) of the nozzle 4 is formed in a horn shape (may be a substantially cylindrical shape or a substantially frustum shape), and the hole diameter of the nozzle 4 is a diameter on the ink droplet outlet side of about 20 to. 35 μm.

  Further, a water repellent treatment layer having a water repellent surface treatment (not shown) is provided on the nozzle surface (surface in the ejection direction: ejection surface) of the nozzle plate 3. Examples of the water-repellent treatment layer include PTFE-Ni eutectoid plating, fluororesin electrodeposition coating, vapor-deposited fluororesin (e.g., fluorinated pitch), silicon resin / fluorine resin A water-repellent film selected according to the recording liquid physical properties such as baking after solvent coating is provided to stabilize the droplet shape and flight characteristics of the recording liquid and to obtain high quality image quality.

  The diaphragm member 2 includes a second layer 2b and a third layer at the center of a diaphragm portion (vibration region) 2A that is a deformable region formed by the first layer 2a corresponding to each pressurized liquid chamber 6. A convex portion 2B having a laminated structure of the layer 2c is formed, and a driving piezoelectric element column 12A of a laminated piezoelectric member constituting pressure generating means (actuator means) is joined to the convex portion 2B.

  The piezoelectric member 12 is formed with a driving piezoelectric element column 12A and a non-driving piezoelectric element column 12B in a comb shape without being divided by half-cut groove processing (slit processing). The piezoelectric member 12 is fixedly disposed on the base member 13 along the arrangement direction of the plurality of piezoelectric element columns 12A and 12B. In this case, the plurality of piezoelectric element columns arranged in a row are a driving piezoelectric element column 12A that is driven alternately and a non-driven piezoelectric element column 12B that is not driven and that is simply a column portion. The non-driving piezoelectric element column 12B, which is a support column, is joined to a portion corresponding to the liquid chamber interval wall 6A.

  The piezoelectric member 12 includes, for example, a lead zirconate titanate (PZT) piezoelectric layer 31 having a thickness of 10 to 50 μm / layer, and an internal electrode layer 32A made of silver and palladium (AgPd) having a thickness of several μm / layer, 32B are alternately stacked, and the internal electrodes 32 are alternately electrically connected to the individual electrodes 33 and the common electrode 34, which are end electrodes (external electrodes) on the end surfaces. The vibration region 2A is displaced by the expansion and contraction of the driving piezoelectric element column 12A whose piezoelectric constant is d33 (d33 indicates the expansion / contraction perpendicular to the internal electrode surface (thickness direction)) so that the liquid chamber 6 contracts and expands. It has become. When the drive signal is applied to the drive piezoelectric element column 12A and charged, it expands, and when the charge charged in the drive piezoelectric element column 12A is discharged, it contracts in the opposite direction.

  It should be noted that the configuration in which the ink in the pressurized liquid chamber 6 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric member 12 or the pressurized liquid chamber is used by using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric member 12. It is also possible to employ a configuration in which the ink in the six is pressurized. In the present embodiment, a configuration using displacement in the d33 direction is adopted.

  The base member 13 is preferably formed of a metal material. If the material (material) of the base member 13 is a metal, heat storage due to self-heating of the piezoelectric element member 12 can be prevented.

  Further, a frame member 17 is joined around the diaphragm member 2 with an adhesive. A common liquid chamber 8 for supplying liquid to each liquid chamber 6 is formed in the frame member 17. A liquid (recording liquid) is supplied from the common liquid chamber 8 to the liquid chamber 6 through the communication portion 9 formed in the diaphragm member 2. The frame member 17 is also formed with an ink supply port for supplying ink to the common liquid chamber 8 from the outside.

  The common liquid chamber 8 is formed in a rectangular shape in a planar shape in the direction in which the pressurized liquid chambers 6 are arranged (nozzle arrangement direction: this is referred to as a “common liquid chamber longitudinal direction”). A part of the wall surface of the common liquid chamber 8 is formed by the vibration plate member 2 and is a deformable region portion (this is referred to as a “damper region”) 20 including only the first layer 2 a of the vibration plate member 2. Is provided. The damper region 20 has lower rigidity than other wall surfaces formed by the frame member 17 and the diaphragm member 2 having a three-layer structure. Details of the damper region 20 will be described later.

  The damper region 20 may be two layers instead of one layer, or only the damper region 20 may be made of a material different from that of the diaphragm member 2. The damper region 20 is preferably made of a material having low gas permeability, such as metal Ni, but may be formed of a resin film or the like. By using a material having a low gas permeability for the damper region 20, even if the head is left without being used for a long period of time, an increase in the viscosity of the liquid in the liquid chamber is less likely to occur.

  In the liquid discharge head configured as described above, for example, the drive piezoelectric element column 12A contracts by lowering the voltage applied to the drive piezoelectric element column 12A from the reference potential, and the vibration region 2A of the diaphragm member 2 descends and is applied. As the volume of the pressure fluid chamber 6 expands, the ink flows into the pressure fluid chamber 6 and then the voltage applied to the drive piezoelectric element column 12A is increased to extend the drive piezoelectric element column 12A in the stacking direction, thereby vibrating. By deforming the vibration region 2A of the plate member 2 in the direction of the nozzle 4 and contracting the volume of the pressurized liquid chamber 6, the ink in the pressurized liquid chamber 6 is pressurized, and ink droplets are ejected (jetted) from the nozzle 4. )

  Then, by returning the voltage applied to the drive piezoelectric element column 12A to the reference potential, the vibration region 2A of the diaphragm member 2 is restored to the initial position, and the pressurized liquid chamber 6 expands to generate a negative pressure. At that time, the ink is filled into the pressurized liquid chamber 6 from the common liquid chamber 8. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform. Strike is to lower the potential from the reference potential, contract the piezoelectric element, increase the internal volume of the pressurized liquid chamber, and then return the potential to the reference potential, thereby returning the diaphragm to the initial position and ejecting droplets. The hitting method and the pressing method are methods of discharging droplets by raising the potential from a reference potential and pushing the diaphragm into the pressurized liquid chamber side.

Next, details of the damper region 20 in the liquid discharge head will be described with reference to FIG. 4A is an explanatory plan view of one damper region, FIG. 4B is an explanatory front view, and FIG. 4C is an explanatory side view.
As shown in FIG. 4, the damper region 20 is composed of one plane region 21 and two deflection regions 22.

  Here, the bending region 22 may be formed by pressing, or may be formed by other means, for example, electrolytic or electroless nickel plating on a substrate having a curved surface in advance. Moreover, the bending area | region 22 is provided so that the longitudinal direction (YY direction) of the area | region may be mutually parallel (including substantially parallel). Further, the longitudinal direction of the bending region 22 is provided substantially parallel to the long side of the entire damper region 20. In addition, it is preferable that the area of the planar region 21 is as large as possible. For this purpose, the two bending regions 22 and 22 are provided not at the center of the damper region 20 but at both ends, and the areas of the bending regions 22 and 22 are as follows. It is preferable that it is as small as possible within a range in which the displacement can be secured.

  In addition, although the bending area | region 22 is arrange | positioned here on both sides on both sides of the plane area 21, here, even if the number of the bending area 22 and the plane areas 21 is larger, a certain effect for increasing the compliance is obtained. I can. In addition, the long sides of the bending region 22, the long side of the bending region 22 and the long side of the damper region 20 are substantially parallel to each other, but even if these are not completely parallel, one or more straight lines, If the planar region 21 of the damper region 20 can be traversed without overlapping the bending region 22, the effect is reduced, but a certain effect can be obtained in accordance with the principle of the present invention. Similarly, the effect of the present invention can be obtained even if there is a discontinuous portion in the bending region 22 (the discontinuous portion is shown in FIG. 1).

The operation of the damper region 20 configured as described above will be described with reference to FIGS. FIG. 5 is an explanatory diagram for explaining a deformed state near X1-X1 in FIG. 4, and FIG. 6 is an explanatory diagram for explaining a deformed state near X2-X2 in FIG.
First, as shown in FIG. 5, one set of opposite directions (in the XX direction in FIG. 5) among two sets of opposite sides around the plane region 21 that is displaced according to pressure as a damper in the damper region 20. On the other side, if the amount of damper displacement is within a range where the deflection region 22 cannot be extended, the tension that impedes the damper function does not work, and the tension that the planar region 21 receives is only from the Y-Y direction.

  Then, in the vicinity of X1-X1 in FIG. 4, which is the vicinity of the end in the longitudinal direction of the damper region 20, the fixed end is close, so that, for example, a pressure of 0.2 kPa is applied as shown in FIG. As shown in FIG. 5B, for example, there is no significant difference between the case where a pressure of 3 kPa is applied, and it cannot be displaced greatly. On the other hand, in the vicinity of X2-X2 in FIG. 4, which is near the longitudinal center of the damper region 20, it is sufficiently far from the fixed end, and a pair of opposite sides can be handled as free ends. As shown in FIG. 6, for example, when a large pressure of 3 kPa is applied as shown in FIG. 6B, the displacement is larger than when a pressure of 0.2 kPa is applied.

Here, a comparative example will be described with reference to FIGS. In addition, the code | symbol uses the same thing as embodiment for description.
A comparative example 1 shown in FIG. 7 is an example having a damper region 20 composed only of a planar region, and a comparative example 2 shown in FIG. 8 is an example having a damper region 20 whose entire surface is previously bent. . In these comparative examples 1 and 2, when the negative pressure in the head is increased by driving the head and the pressure wave is suppressed by the deformation of the damper region 20 from the state of FIG. If the region 20 is deformed even slightly, a tension T in the cross-section direction is generated in a direction in which the region 20 is inhibited, and as a result, tension from all four sides forming the damper region 20 is obtained. The function of the damper will be hindered by receiving.

  That is, the configuration of the damper region according to the present embodiment is less susceptible to the inhibition of the damper function due to the tension as compared with Comparative Examples 1 and 2, so that a greater pressure wave suppression effect can be obtained. As a result, it is possible to increase the speed and improve the image quality while keeping the area of the damper region 20 small.

  Thus, a deformable region portion is provided in a part of the member forming the wall surface of the common liquid chamber, and the deformable region portion has a flat region and a plurality of bending regions across the flat region. In addition, by adopting a configuration in which the bending regions are arranged in parallel with each other in the nozzle arrangement direction, a larger pressure wave absorption effect can be obtained with a small area.

  In other words, among the four sides surrounding the planar area that functions as a damper, at least two sides facing each other can be treated as free ends by bending, so that when the damper is displaced under pressure, the deflection does not fully extend. As long as it is displaced, the planar region is not subjected to tension from the two sides having deflection. Therefore, compared to the previous configuration where deformation is hindered by deformation from the surrounding four sides when the damper is deformed, large structural compliance can be obtained, and pressure waves are effectively suppressed with a small area damper. can do. Thereby, the adverse effect of pressure waves on image formation is suppressed.

  This effect cannot be obtained when the entire planar area serving as a damper (Comparative Example 2) or all four sides surrounding the planar area are bent (in this case, the deformation is lost but the restoring force is lost). As a function). In other words, the presence of a bending region on two or more substantially parallel sides across the plane region yields a restoring force that causes the plane region to return to a flat state upon displacement. It can be done.

  In addition, the following effects can be obtained by having the restoring force of the plane region returning to the plane. For example, in the structure in which the entire deflection including the center of the damper portion (the structure of Comparative Example 2) is formed, the damper portion is always bent in the liquid flow path of the head due to the negative pressure always present in the head. Since expansion and contraction as a damper is performed around the bending, it becomes a factor of narrowing the liquid flow path and increasing fluid resistance. On the other hand, as in the above embodiment, horizontal tension acts on a pair of opposed sides around the planar region that becomes the damper region, and this acts as a restoring force as described above. Vibrates around a line connecting both ends of the planar region when the effect of the damper is exhibited. This makes it difficult to narrow the liquid flow path as compared with a configuration in which a deflection exists in the center of the damper.

  In this case, as in the above-described embodiment, at least two of the plurality of bending regions 22 are provided at positions adjacent to the boundary between the damper region 20 and another region (the three-layer structure portion of the diaphragm member 2). As a result, a planar region having a larger area can vibrate as a damper, so that the compliance of the damper region can be further increased.

  In addition, since the longitudinal direction of the bending region 22 is substantially parallel to the long side of the damper region 20, compared to the case where it is substantially parallel to the short side of the damper region 20, more Large structural compliance can be obtained.

  In addition, since the planar region 20 has one or more free ends and is likely to be deformed and plays a larger role as a damper, the area of the planar region 21 is made larger than the area of the deflecting region 22, Compliance can be increased.

  In addition, since the two deflection regions 22 and 22 are arranged across the planar region 21, the area of the planar region 21 having a free end having a large compliance becomes larger, so that the compliance of the structure of the entire damper region 20 can be reduced. In addition, since the bending portion that is deformed by the negative pressure in the head and narrows the flow path becomes small, an increase in fluid resistance can be prevented.

  In addition, the damper area 20 is formed by a part of the diaphragm member 2, and the damper area can be more easily assembled by configuring the member forming the wall surface of the common liquid chamber 8 and the damper area with a single material. It can be carried out. Further, by constituting the common liquid chamber 8 with the member forming the wall surface, the damper region 20 and the metal, the gas barrier property is higher than that of the film made of the polymer material, and it is non-existent even when left at a high temperature for a long time. It is possible to obtain a damper region in which reversible contraction hardly occurs and structural compliance can be easily maintained.

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 9 is an explanatory plan view of one damper region in the same embodiment.
In this embodiment, the bending region 22 formed on the damper region 20 is arranged not to be parallel to the longitudinal direction of the damper region 20 but to be inclined. Even in this shape, the planar region 21 without deflection is subjected to linear tension, and the two sides in contact with the deflection region 22 are free ends that are not fixed. An effect comes to be acquired.

Next, a third embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 10 is an explanatory plan view of one damper region in the same embodiment. Embodiments will be described.
In this embodiment, the bending regions 22 formed on the damper region 20 are arranged in the short side direction (direction orthogonal to the long side direction) of the damper region 20, and the number of the bending regions 22 and the planar regions 21 is set. It is an increase. Even if it is such a structure, the effect similar to the said embodiment can be acquired. In this case, as shown in FIG. 10, the interval between the bending regions 22 may not be constant. Moreover, compared with the said 1st Embodiment, there exists an advantage that it becomes easy to form the bending area | region 22 because the area of the bending area | region 22 becomes small.

  The liquid discharge head can be configured as a cartridge-integrated head integrated with an ink tank.

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. 11 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 12 is a plan view of 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 a main scanning direction by main and sub guide rods 231 and 232 which are guide members horizontally mounted on 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 ejection head according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows composed of 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.

  Each of the recording heads 234 has two nozzle rows, one of the two nozzle rows of one head 234a is a black (K) droplet, and the other two nozzle rows are cyan (C) liquid. The two nozzle rows of the other head 234b eject magenta (M) droplets, and the other two nozzle rows eject yellow (Y) droplets. Note that, here, a four-color droplet is ejected with a two-head configuration, but each of the four colors can be ejected with one head in a four-nozzle row arrangement per head.

  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, the droplet discharge performance is improved, so that a high-quality image can be formed by performing stable droplet discharge.

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. FIG. 13 is a schematic configuration diagram of the entire mechanism unit 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, 412d, 412m, 412y (referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) for maintaining and recovering the performance of the head corresponding to each recording head 411 is provided. 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 predetermined intervals can be used, and a recording liquid cartridge for supplying a recording liquid to the head and the head. Can be integrated or separated.

  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 conveyance belt 433 at the opposite portion, a pressing roller 436 that presses the paper 403 fed from the conveyance belt 433 against the conveyance roller 431 side, and other recording liquid that is attached to the conveyance belt 433, although not shown. It has a cleaning roller made of a porous material or the like, which is a cleaning means for removing (ink).

  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. 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, the droplet discharge performance is improved. Therefore, stable droplet discharge is performed to form a high-quality image at high speed. be able to.

  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, and as described above, for example, an image forming apparatus such as a printer / fax / copier multifunction machine. In addition, the present invention can also be applied to an image forming apparatus using a liquid other than the narrowly defined ink or a fixing processing liquid.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Diaphragm member 2a 1st layer 2b 2nd layer 2c 3rd layer 2A Vibration area 2B Island-shaped convex part 3 Nozzle plate 4 Nozzle 6 Liquid chamber 7 Supply path (fluid resistance part)
8 Common liquid chamber 12 Piezoelectric member 12A Drive piezoelectric element column (drive unit)
12B Non-driving piezoelectric element pillar (post)
13 Base member 17 Frame member 20 Damper area (deformable area)
21 Planar area 22 Deflection area 233 Carriage 234 Recording head (liquid ejection head)

Claims (7)

A plurality of nozzles for discharging droplets;
An individual flow path through which the nozzle communicates;
A common liquid chamber for supplying liquid to each individual flow path,
A deformable region portion is provided in a part of the member forming the wall surface of the common liquid chamber,
The deformable region portion has a planar region and a plurality of bending regions across the planar region,
The liquid ejection head, wherein the plurality of flexure regions are arranged in parallel to each other.   2. The liquid ejection head according to claim 1, wherein the bending region is provided adjacent to a boundary where the deformable region portion contacts the non-deformable region portion.   The liquid ejection head according to claim 1, wherein the plurality of bending regions are provided along a nozzle arrangement direction.   4. The liquid discharge head according to claim 1, wherein the deformable region portion has an area of the planar region larger than an area of the plurality of bending regions. 5.   5. The liquid ejection head according to claim 1, wherein the deformable region portion is provided with two bending regions on both sides of the one planar region. 6.   The member forming the wall surface of the common liquid chamber is a diaphragm member having a multilayer structure, and the deformable region portion is formed by a part of the layer of the diaphragm member. The liquid discharge head according to any one of 5 to 5.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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