JP2008068476A - Liquid discharge head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that discharge efficiency is decreased because mutual interference is caused by the fluctuation of a channel plate and a nozzle plate, when high-density arrangement is performed by a head for a piezoelectric element to a diaphragm. <P>SOLUTION: This liquid discharge head comprises the diaphragm 2 which forms a wall surface of a pressure liquid chamber 6 communicating with a nozzle 4 for ejecting a droplet, and the piezoelectric element 12 which pressurizes a liquid in the pressure liquid chamber 6 via the diaphragm 2. The diaphragm 2 is provided with a connecting portion 11 which is joined to the piezoelectric element 12. The connecting portion 11 comprises a first layer 11A on the side of the diaphragm 2, and a second layer 11B on the side of the piezoelectric element 12. The first layer 11A is formed in such a shape that its width in the short-side direction (y-direction) of the pressure liquid chamber is narrower than that of the pressure liquid chamber 6, and continuously formed throughout the pressure liquid chamber 6 in the longitudinal direction (x-direction) of the pressure liquid chamber. The second layer 11B is formed in such a shape that the longitudinal (x-direction) length of the pressure liquid chamber is shorter than that of the first layer 11A, and that the short-side-direction (y-direction) width of the pressure liquid chamber is equal to that of the first layer 11A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid discharge head and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine of these, for example, a liquid (e.g., a liquid ejecting apparatus) including a recording head composed of a liquid ejecting head for ejecting liquid droplets of a recording liquid (liquid) is used. Hereinafter, although it is also referred to as “paper”, the material is not limited, and a recording medium as a liquid (hereinafter, referred to as “recording medium”, “recording medium”, “transfer material”, “recording paper” and the like is also used synonymously). Some of them perform image formation (recording, printing, printing, and printing are also used synonymously) by attaching the ink to the paper.

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” 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. Further, the liquid is not limited to the recording liquid and ink, and is not particularly limited as long as it is a liquid capable of forming an image. Further, the liquid ejection apparatus means an apparatus that ejects liquid from a liquid ejection head, and is not limited to an apparatus that forms an image.

  As the liquid discharge head, for example, a nozzle plate in which nozzles for discharging droplets are formed, a flow path member (flow path plate) that forms a liquid chamber in which the nozzles communicate, a vibration plate that forms one wall surface of the liquid chamber, A device including a piezoelectric element as pressure generating means (energy generating means) that generates energy for pressurizing liquid in a liquid chamber via a vibration plate is known.

As a liquid discharge head using such a piezoelectric element, there is a bi-pitch structure in which piezoelectric elements that are driven and displaced and piezoelectric elements that are columns are alternately arranged, and a piezoelectric that is a column that is arranged only by piezoelectric elements that are driven and displaced. A normal pitch structure with no elements is known.
It consists of an actuator unit. The bi-pitch structure head supports the flow path member that forms the liquid chamber with the support, so that when the piezoelectric element is driven, the flow path member and the entire nozzle plate are displaced, so that the liquid chamber is not driven. Although it is possible to reduce the mutual interference that the pressure change occurs and the droplet ejection characteristics fluctuate, the nozzle pitch becomes relatively wide due to the support columns interposed between the piezoelectric elements, and as a result, it is difficult to arrange the nozzles at high density. . On the other hand, since the head having the normal pitch structure is easy to increase in density because there is no support portion for supporting the flow path member, mutual interference is likely to occur.

  In addition, when the number of nozzles increases due to higher density, in order to reduce the current consumption per channel (a general term for each part corresponding to one nozzle), it is possible to drive at a lower voltage, that is, the ejection efficiency is reduced. There is a demand for improvement.

Conventionally, in order to suppress such mutual interference and improve discharge efficiency, for example, Patent Document 1 discloses that a non-driving column (support portion) is made of a material having a larger elastic coefficient than a driving column. It is described that the cross-sectional area of the non-driving column is increased by making the cross-sectional area of the non-driving column larger than the cross-sectional area of the driving column.
JP 2000-351207 A

In Patent Document 2, the end of the laminated piezoelectric body opposite to the joint surface with the diaphragm is in a state of an unconstrained end that can be displaced in the pressurizing direction to the diaphragm by the laminated piezoelectric body. It is described that a liquid in a pressure chamber is pressurized through a vibration plate by expansion and contraction of a piezoelectric body so that a droplet is discharged from a nozzle.
JP 2005-125773 A

Patent Document 3 describes that a diaphragm is easily deformed by forming a recess in the approximate center of a piezoelectric element arrangement region of the diaphragm.
JP 2005-104038 A

In Patent Document 4, the diaphragm and the piezoelectric element are joined via a relay member, the length of the relay member in the direction orthogonal to the nozzle row direction is Tf, and the nozzle row on the surface to be joined to the relay member of the piezoelectric element. It is described that Ta <Tf <Tp, where Tp is the length in the direction orthogonal to the direction and Ta is the active portion length in the direction orthogonal to the nozzle row direction of the surface joined to the relay member of the piezoelectric element. Has been.
JP 2005-014506 A

In Patent Document 5, the diaphragm is composed of a thin part and a thick part, and the region of the thin part is separated by the thick part with which the driving means abuts, that is, in the longitudinal direction of the diaphragm. It is described that a thick-walled portion having a narrower width than the transverse direction of the diaphragm is continuously formed over the entire region in the longitudinal direction of the liquid chamber.
JP 2003-019793 A

Patent Document 6 describes that a diaphragm and a transducer corresponding to a piezoelectric element are connected via an incompressible viscoelastic member.
Japanese Patent Publication No. 02-052625

  However, as described in Patent Document 1, the non-driving column (support portion) is formed of a material having a larger elastic coefficient than the driving column, or the cross-sectional area of the non-driving column is made larger than the cross-sectional area of the driving column. In the configuration, the structure of the driving column and the non-driving column is different, and design restrictions are increased due to the construction method. For example, in order to increase the rigidity, it is necessary to arrange materials having different rigidity, the construction method becomes complicated, and there is a problem that increasing the width of the non-driven column cannot increase the density.

  As described in Patent Document 2, in the configuration in which the end opposite to the joint surface with the diaphragm of the laminated piezoelectric body is not completely fixed, the displacement of the piezoelectric body is absorbed, and the discharge There is a problem that efficiency decreases.

  In the configuration in which the concave portion is formed in the approximate center of the piezoelectric element arrangement region of the diaphragm as described in Patent Document 3, not only the processing of the concave portion is difficult, but if the rigidity of the diaphragm is too low, There is a problem that the discharge efficiency is lowered due to the absorption of the indoor pressure.

  In the configuration in which a thick portion having a narrower width than the short direction of the diaphragm is continuously formed in the longitudinal direction of the diaphragm in the longitudinal direction of the diaphragm as described in Patent Document 5, The entire piezoelectric element is connected to the diaphragm via the thick wall, making the structure vulnerable to mutual interference. If the position accuracy of the piezoelectric element is poor, the flow path member that forms the liquid chamber interferes with the piezoelectric element. Thus, there is a problem that the piezoelectric element may lift the flow path member.

  The present invention has been made in view of the above problems, and provides a liquid discharge head in which mutual interference is suppressed even when nozzles are arranged in high density and discharge efficiency does not decrease, and an image forming apparatus including the liquid discharge head. For the purpose.

  In order to solve the above-described problems, in the liquid discharge head according to the present invention, the diaphragm is provided with a connecting portion that joins the pressure generating means, and the connecting portion includes at least the first layer on the diaphragm side and the pressure generating means side. The first layer has a shorter width in the lateral direction of the pressurized liquid chamber than the width of the pressurized liquid chamber, and is continuous over the entire pressurized liquid chamber in the longitudinal direction of the pressurized liquid chamber. The second layer is configured such that the length of the pressurized liquid chamber in the longitudinal direction is shorter than that of the first layer.

  Here, the 1st layer and 2nd layer which comprise a connection part can be set as the structure currently formed with the same material. Further, the length of the second layer in the longitudinal direction of the pressurized liquid chamber can be shorter than the length of the pressure generating means in the longitudinal direction of the pressurized liquid chamber. In this case, the length of the pressurized liquid chamber in the longitudinal direction is the pressure generated. It can be configured to be shorter than the length of the means in the longitudinal direction of the pressurized liquid chamber. Moreover, it can be set as the structure whose viscosity of a liquid is 20 cp or more.

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

  According to the liquid discharge head of the present invention, the diaphragm is provided with a connecting portion that is joined to the pressure generating means, and the connecting portion includes at least a first layer on the diaphragm side and a second layer on the pressure generating means side. The first layer has a shorter width in the lateral direction of the pressurized liquid chamber than the width of the pressurized liquid chamber, and is continuously formed over the entire pressurized liquid chamber in the longitudinal direction of the pressurized liquid chamber. Since the layer has a configuration in which the length in the longitudinal direction of the pressurized liquid chamber is shorter than that of the first layer, the excluded volume increases because the first layer is formed in the entire pressurized liquid chamber. The discharge efficiency is improved, and the second layer is interposed between the first layer and the pressure generating means, so that mutual interference is reduced and high density can be achieved.

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

  Hereinafter, the best mode for carrying out the present invention will be described. An embodiment of the liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional view of the head along the longitudinal direction of the liquid chamber, FIG. 3 is an enlarged view of the main part of FIG. 2, and FIG. FIG. 5 is an explanatory plan view for explaining the relationship between the vibration plate, the connecting portion and the piezoelectric element of the head. FIG. 6 is a cross section of the head along the short direction of the liquid chamber when the bi-pitch structure is used. FIG. 7 is an explanatory view and FIG. 7 is a cross-sectional explanatory view along the short side direction of the liquid chamber of the head when the normal pitch structure is adopted.

  The liquid discharge head includes, for example, a flow path plate 1 formed of a silicon substrate, a vibration plate 2 bonded to the lower surface of the flow path plate 1, and a nozzle plate 3 bonded to the upper surface of the flow path plate 1. As a result, the nozzle 4 for ejecting ink droplets forms a pressurized liquid chamber 6 that communicates via the communication path 5, a fluid resistance portion 8, and a communication portion 9 that communicates with the liquid chamber 6 via the fluid resistance portion 7. A recording liquid (for example, ink) as a liquid is supplied to a portion 9 from a common liquid chamber 8 formed in a frame member 17 described later through a supply port 10 formed in the diaphragm 2.

  Then, on the outer side of the diaphragm 2 that forms the wall surface of the liquid chamber 6 (on the side opposite to the liquid chamber 6), corresponding to each pressurized liquid chamber 6, via a connecting portion 11 formed on the diaphragm 2. The upper end portion of the multilayer piezoelectric element 12 as pressure generating means is joined, and the lower end portion of the multilayer piezoelectric element 12 is joined and fixed to the support substrate 13. Note that the support substrate 13 may be divided for each row of the piezoelectric elements 12.

  The piezoelectric element 12 is formed by alternately stacking piezoelectric material layers 14 and internal electrodes 15a and 15b. In this case, the ink in the liquid chamber 6 may be pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 12, or the pressurized liquid chamber 6 using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 12. It can also be configured to pressurize the inner ink.

  Further, the periphery of the flow path plate 1 and the vibration plate 2 is bonded and bonded to a frame member 17 formed by injection molding with, for example, epoxy resin or polyphenylene sulfite, and the frame member 17 and the support substrate 13 are bonded to a portion (not shown). They are fixed to each other with agents. The frame member 17 is formed with the above-described common liquid chamber 8 and a supply path (communication pipe) (not shown) for supplying recording liquid from the outside to the common liquid chamber 8. Further, it is connected to a recording liquid supply source such as a recording liquid cartridge (not shown).

  Further, an FPC cable 18 is connected to the piezoelectric element 12 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. The FPC cable 18 is selectively connected to each piezoelectric element 12. A drive circuit (driver IC) 19 for applying a drive waveform is mounted.

  In the liquid ejection head configured as described above, for example, by lowering the voltage applied to the piezoelectric element 12 from the reference potential, the piezoelectric element 12 contracts, and the diaphragm 2 descends to expand the volume of the liquid chamber 6. Then, ink flows into the liquid chamber 6, and then the voltage applied to the piezoelectric element 12 is increased to extend the piezoelectric element 12, and the diaphragm 2 is deformed in the direction of the nozzle 4 to contract the volume / volume of the liquid chamber 6. As a result, the ink in the liquid chamber 6 is pressurized, and ink droplets are ejected (jetted) from the nozzle 4.

  Then, by returning the voltage applied to the piezoelectric element 12 to the reference potential, the diaphragm 2 is restored to the initial position, and the liquid chamber 6 expands to generate a negative pressure. At this time, the liquid 6 is discharged from the common liquid chamber 8. Inside is filled with ink. 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.

Therefore, the connecting portion 11 formed on the diaphragm 2 in this liquid discharge head will be described with reference to FIG.
The diaphragm 2 is provided with a connecting portion 11 to be joined to the piezoelectric element 12, and the connecting portion 11 has a first layer 11A on the diaphragm 2 side and a second layer 11B on the piezoelectric element 12 side. 4 and 5, the longitudinal direction of the pressurized liquid chamber 6 (the direction along the direction orthogonal to the direction in which the pressurized liquid chambers are arranged, or the direction along the direction perpendicular to the direction in which the nozzles are arranged) Is the same as the x direction, and the short side direction of the pressurized liquid chamber (the direction along the direction in which the pressurized liquid chambers are aligned and the direction along the direction in which the nozzles are aligned) is the “y direction”. The layer 11A has a width in the short side (y direction) of the pressurized liquid chamber shorter than the width of the pressurized liquid chamber 6, and continuously over the entire pressurized liquid chamber 6 in the longitudinal direction of the pressurized liquid chamber (x direction). The second layer 11B is formed such that the length of the pressurized liquid chamber in the longitudinal direction (x direction) is shorter than that of the first layer 11A, and the width of the pressurized liquid chamber in the short direction (y direction) is the same as that of the first layer 11A. It is formed in the same way. In addition, although it is set as 2 layer structure here, it can also be set as the structure of 3 or more layers.

  Thus, since the first layer 11A on the diaphragm 2 side constituting the connecting portion 11 that couples the piezoelectric element 12 and the diaphragm 2 is continuously formed over the entire longitudinal direction of the pressurized liquid chamber, Compared to the case where only part of the piezoelectric element 12 is formed, the excluded volume is increased and the discharge efficiency is improved. The second layer 11B on the piezoelectric element 12 side is shorter than the first layer 11A. 2 is connected only near the central portion of the piezoelectric element 12, so that mutual interference is less likely to occur.

  Here, the x-direction length Xb of the second layer 11B of the connecting portion 11 is preferably shorter than the x-direction length Xp of the piezoelectric element 12, as shown in FIG. As a result, even when the position of the piezoelectric element 12 is shifted in the x direction, the portion to which the displacement of the piezoelectric element 12 is transmitted can be adjusted in the region where the second layer 11B is present, and characteristic variation can be reduced. it can.

  In addition, the x-direction length Xc of the pressurized liquid chamber 6 is preferably shorter than the x-direction length Xp of the piezoelectric element 12. As a result, the size of the pressurized liquid chamber 6 can be shortened, the head can be miniaturized, and by increasing the resonance frequency of the liquid chamber, stable droplet discharge can be performed without causing resonance even if the head drive frequency is increased. It can be carried out.

  This liquid discharge head improves discharge efficiency, so that even a high-viscosity recording liquid having a viscosity of 20 cp or more can be discharged. In the case of high-viscosity recording liquid, the problem of remaining bubbles will occur if the pressurized liquid chamber is not miniaturized. However, in this liquid discharge head, the size of the pressurized liquid chamber can be determined regardless of the shape of the piezoelectric element. Is less likely to occur.

  Further, the first layer 11A, the second layer 11B, and the diaphragm 2 constituting the connecting portion 11 can be formed of the same material by, for example, nickel electroforming.

Next, a specific first embodiment will be described.
As Example 1, a Si substrate having a thickness of 500 μm is used for the flow path plate 1, and a pressurized liquid chamber 6 having a height of 100 μm, a length of 1000 μm in the longitudinal direction of the liquid chamber, and a width of 150 μm in the lateral direction is formed thereon. . Moreover, the diaphragm 2 having a thickness of 3 μm, the first layer 11A having a thickness of 6 μm, and the second layer 11B having a thickness of 6 μm and a length of 500 μm in the liquid chamber longitudinal direction are formed by Ni electroforming.

  Then, the diaphragm 2 is joined to the flow path plate 1, and the piezoelectric element 12 made of lead zirconate titanate is attached to the second layer 11 </ b> B of the connecting portion 11 of the diaphragm 2. The piezoelectric element 12 has a 16-layer laminated structure in which the piezoelectric layer 14 is sandwiched from above and below by silver and palladium electrodes 15a and 15b. Each layer has a thickness of 25 μm, an inactive portion of 100 μm is provided on the top of 16 layers and 300 μm on the bottom, and the height of the piezoelectric element 12 as a whole is 800 μm. In the liquid chamber longitudinal direction, the length of the active portion 25 is 700 μm, the length of the inactive portion 26 is 200 μm on both sides of the active portion 25, and the length in the liquid chamber longitudinal direction of the piezoelectric element 12 is 1100 μm as a whole. .

  Further, as Comparative Example 1, as shown in FIGS. 8 and 9, the head was manufactured with a structure in which only the second layer 11 </ b> B was used as the connecting portion and the length of the connecting portion (second layer 11 </ b> B) was 700 μm.

  Each head of Example 1 and Comparative Example 1 was assembled in an image forming apparatus (inkjet recording apparatus) having a printer configuration, and a comparison was made by a printing test.

  As a result, in the printer equipped with the head of Example 1, the droplet ejection speed from the nozzle 4 was 13 m / sec, whereas in the printer equipped with the head of Comparative Example 1, the droplet from the nozzle 4 was used. The discharge speed decreased to 11.5 m / sec, and it was confirmed that the relative discharge efficiency of the liquid discharge head according to the present invention was good.

Next, a specific second embodiment will be described.
As Example 2, a Si substrate having a thickness of 500 μm is used for the flow path plate 1, and a pressurized liquid chamber 6 having a height of 100 μm, a length of 1000 μm in the longitudinal direction of the liquid chamber, and a width of 150 μm in the lateral direction is formed thereon. . Further, the diaphragm 2 having a thickness of 3 μm, the first layer 11A having a thickness of 6 μm, and the second layer 11B having a thickness of 6 μm and a length of 800 μm in the liquid chamber longitudinal direction are formed by Ni electroforming.

  Then, the diaphragm 2 is joined to the flow path plate 1, and the piezoelectric element 12 made of lead zirconate titanate is attached to the second layer 11 </ b> B of the connecting portion 11 of the diaphragm 2. The piezoelectric element 12 has a 16-layer laminated structure in which the piezoelectric layer 14 is sandwiched from above and below by silver and palladium electrodes 15a and 15b. Each layer has a thickness of 25 μm, an inactive portion of 100 μm is provided on the top of 16 layers and 300 μm on the bottom, and the height of the piezoelectric element 12 as a whole is 800 μm. Further, in the longitudinal direction of the liquid chamber, the length of the active portion 25 is 900 μm, the length of the inactive portion 26 is 150 μm on both sides of the active portion 25, and the overall length of the piezoelectric chamber 12 in the liquid chamber is 1200 μm as a whole. .

  Further, as Comparative Example 2, as shown in FIGS. 10 and 11, a head having a structure in which only the first layer 11 </ b> A was used as a connecting portion was manufactured.

  The heads of Example 2 and Comparative Example 2 were assembled in an image forming apparatus (inkjet recording apparatus) having a printer configuration, and a comparison was made by a printing test.

  As a result, in the printer equipped with the head of Example 2, a good result was obtained that did not cause defective image quality. In the printer equipped with the head of Comparative Example 2, a plurality of white streaks occurred. A defective image such as this occurred and the characteristic improvement effect of the present invention was confirmed.

Next, an example of an image forming apparatus including a liquid discharge apparatus including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 12 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 13 is a plan view for explaining a main portion of the mechanism portion.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and sub guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 201A and 201B. 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 has recording heads 234a and 234b (which are composed of liquid ejection heads according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). When not distinguished, it is referred to as “recording head 234”). A nozzle row composed of a plurality of nozzles is arranged in the sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ink droplet ejection direction facing downward.

  Each of the recording heads 234 has two nozzle rows. One nozzle row of the recording head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 234b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  The carriage 233 is equipped with head tanks 235a and 235b (referred to as “head tank 35” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub-tank 235 is supplementarily supplied with ink of each color from the ink cartridges 210k, 210c, 210m, 210y of each color via the supply tube 36 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. 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 of FIG. 20 when the transport roller 252 is rotationally driven by a sub scanning motor (not shown) through timing.

  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 for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  In addition, in the non-printing area on the other side in the scanning direction of the carriage 233, the liquid that receives liquid droplets when performing idle ejection that ejects liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ink recovery unit (empty discharge receiver) 288 that is a recovery container is disposed, and the ink recovery unit 288 includes 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, the image forming apparatus includes the liquid discharge head according to the present invention in which mutual interference is suppressed even when the nozzles are arranged in high density and the discharge efficiency does not decrease, so that a high-quality image can be formed. .

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. Further, the present invention can also be applied to a liquid ejecting apparatus or an image forming apparatus that uses a liquid such as a recording liquid other than ink, a DNA sample, or a resist.

1 is an exploded perspective view showing an embodiment of a liquid discharge head according to the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. FIG. 3 is an enlarged view of a main part of FIG. 2. It is principal part expanded sectional explanatory drawing of the connection part vicinity of the diaphragm of the head. It is a plane explanatory view explaining the relation of the diaphragm of the head, a connecting part, and a piezoelectric element. It is sectional explanatory drawing in alignment with the liquid chamber transversal direction of the head at the time of setting it as a bipitch structure. It is sectional explanatory drawing along the transversal direction of the liquid chamber of the head at the time of setting it as a normal pitch structure. FIG. 6 is a cross-sectional explanatory diagram of a main part along the liquid chamber longitudinal direction of the head of Comparative Example 1. It is a plane explanatory view explaining the relation of the diaphragm of the head, a connecting part, and a piezoelectric element. 10 is a cross-sectional explanatory diagram of a main part along a liquid chamber longitudinal direction of a head of Comparative Example 2. FIG. It is a plane explanatory view explaining the relation of the diaphragm of the head, a connecting part, and a piezoelectric element. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flow path plate 2 ... Vibration plate 3 ... Nozzle plate 4 ... Nozzle 11 ... Connection part 11A ... 1st layer 11B ... 2nd layer 12 ... Piezoelectric element 233 ... Carriage 234 ... Recording head

Claims (6)

In a liquid ejection head comprising: a diaphragm that forms a wall surface of a pressurized liquid chamber that communicates with a nozzle that ejects droplets; and a pressure generating means that pressurizes the liquid in the pressurized liquid chamber via the diaphragm.
The diaphragm is provided with a connecting portion for joining with the pressure generating means,
This connecting portion is composed of at least a first layer on the diaphragm side and a second layer on the pressure generating means side,
The first layer has a width in the short direction of the pressurized liquid chamber shorter than a width of the pressurized liquid chamber, and is continuously formed over the entire pressurized liquid chamber in the longitudinal direction of the pressurized liquid chamber,
The liquid ejection head, wherein the second layer is formed so that the length of the pressurized liquid chamber in the longitudinal direction is shorter than that of the first layer.   The liquid discharge head according to claim 1, wherein the first layer and the second layer constituting the connecting portion are formed of the same material.   3. The liquid ejection head according to claim 1, wherein a length of the second layer in the longitudinal direction of the pressurized liquid chamber is shorter than a length of the pressure generating unit in the longitudinal direction of the pressurized liquid chamber. Discharge head.   4. The liquid discharge head according to claim 3, wherein the longitudinal length of the pressurizing liquid chamber is shorter than the length of the pressure generating means in the longitudinal direction of the pressurizing liquid chamber.   5. The liquid discharge head according to claim 1, wherein the liquid has a viscosity of 20 cp or more.   6. An image forming apparatus for forming an image with a liquid discharge head, comprising the liquid discharge head according to claim 1.

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