JP2006218673A - Nozzle plate for liquid ejection head, manufacturing method therefor, liquid ejection head, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that ejection efficiency is decreased by having a pressure loss increased because fluid resistance is increased on the grounds that hole parts, forming nozzles, of respective layers in a nozzle plate with a laminated structure, are formed in such a shape as to have the same diameter. <P>SOLUTION: In the nozzle plate 10, a second member 12, in which a hole part 12a communicating with a hole part 11a of a first member 11 is formed, is provided on the surface, in the direction opposite to a droplet ejecting direction, of the first member 11 wherein the hole part 11a constituting the nozzle 9 for ejecting the droplet is formed. The second member 12 has a thickness t2; the surface of a laminated boundary face between the first and second members 11 and 12 has a nozzle diameter d2; the first member 11 has a thickness t1; an ejection surface has a nozzle diameter d1; the thicknesses of the respective members 11 and 12 satisfy the relationship, t1<t2; the nozzle diameters satisfy the relationship, d1<d2; and the hole part 11a of the first member 11 and the hole part 12a of the second member 12 are made concentric with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nozzle plate for a liquid discharge head, a method for manufacturing a nozzle plate for a liquid discharge head, a liquid discharge head, and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, and a multifunction machine of these, for example, an ink jet recording apparatus is known. The ink jet recording apparatus uses a liquid discharge head as a recording head, and is a recording medium such as recording paper (hereinafter referred to as “paper”, but the material is not limited to paper, and the recording medium, transfer paper, transfer material, Recording is also performed by ejecting ink droplets as a recording liquid onto the recording material, etc. (image formation, printing, printing, printing, etc. are also synonymous).

  When the liquid discharge head used for achieving high-speed recording in such an image forming apparatus is lengthened or lined, it is one of the problems to reduce the variation in nozzle hole diameter in the head. . Further, as the size of the head increases, the manufacturing cost of the nozzle plate also increases. Therefore, in order to produce a nozzle plate by simultaneously drilling a large number of nozzle holes by photolithography and etching methods, the following techniques have been proposed.

For example, as described in Patent Document 1, a nozzle plate having a laminated structure in which Ni is laminated on polyimide, and the formation process of the nozzle plate is an oxygen plasma excited on polyimide by the ECR method using Ni as a hard mask. There is a nozzle plate in which nozzle holes are drilled by dry etching.
Japanese Patent Laid-Open No. 2004-9745

As described in Patent Document 2, after laminating a metal such as Al, Ni, Cu or the like on a polyimide plate, this is patterned, and the polyimide plate is subjected to oxygen plasma by helicon waves using the patterned metal film as a mask. There is a nozzle plate in which nozzle holes are formed by dry etching.
JP 2000-218798 A

As described in Patent Document 3, dry etching is performed on a plastic film using an inorganic film such as a metal or Si oxide film as a hard mask to drill a nozzle hole. At this time, the etching mask is controlled by controlling the etching conditions. There is a nozzle plate in which the hole diameter of the plastic film is perforated smaller than the diameter of the hole to form a tapered nozzle hole.
JP-A-6-238903

As described in Patent Literature 4, there is a nozzle plate in which a nozzle plate and a nozzle reinforcing plate, which have been processed in advance with different hole sizes, are bonded and integrated with a polymer film adhesive.
JP-A-10-67102

As described in Patent Document 5, in order to improve the variation in nozzle hole diameter and liquid discharge characteristics in a nozzle plate having a laminated structure, the nozzle communication hole diameter D of the rigid substrate and the nozzle of the resin film There is a nozzle plate having a laminated structure in which the relationship D / d with the hole diameter d takes a value of 1.3 to 8.
JP 2002-240294 A

  However, in the nozzle plate described in Patent Document 1, polyimide is perforated so as to have the same opening diameter as the Ni hard mask. That is, since the nozzle diameter of the Ni hard mask member and the nozzle diameter of the polyimide member are formed to be equal, the fluid resistance increases and the pressure loss increases, resulting in an increase in injection voltage and a decrease in discharge efficiency. There is.

  Further, even in the nozzle plate described in Patent Document 2, since polyimide is perforated with a hole diameter equal to that of the patterned metal film, the fluid resistance increases and the pressure loss increases. There is a problem of causing an increase and a decrease in discharge efficiency.

  Furthermore, in the nozzle plate described in Patent Document 3, since the nozzle plate must be manufactured and aligned and bonded to the liquid chamber substrate, there is a problem that an alignment process is separately required and the process becomes complicated. .

  Further, in the nozzle plate described in Patent Document 4, since the constituent members are aligned and adhesively bonded, not only the process becomes complicated, but also the ink ejection characteristics due to misalignment between the nozzle plate and the nozzle reinforcing plate. There is a problem of causing deterioration.

  Furthermore, in the nozzle plate described in Patent Document 5, in order to separately drill the nozzle communication hole of the rigid substrate and the nozzle hole of the resin film, the center of each hole may be formed differently, There is a problem that the image quality is deteriorated due to variations in the droplet discharge direction depending on the nozzle.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and improves the liquid ejection efficiency and reduces the variation in the liquid ejection direction, the method for producing the nozzle plate, the liquid ejection head, and image formation An object is to provide an apparatus.

  In order to solve the above problems, a nozzle plate for a liquid discharge head according to the present invention has a surface opposite to the liquid droplet discharge direction of the first member in which a hole constituting a nozzle for discharging liquid droplets is formed. In the nozzle plate for a liquid discharge head provided with the second member in which the hole portion communicating with the hole portion of the first member is provided, the hole portion of the second member at the interface between the first member and the second member Is larger than the diameter of the hole of the first member on the discharge surface side, and the center of the hole of the first member and the center of the hole of the second member are formed concentrically. The configuration.

  Here, it is preferable that the thickness of the first member is thinner than the thickness of the second member. Further, it is preferable that the first member has a relatively low etching rate with respect to the etchant used when the second member is etched. Furthermore, it is preferable that the first member is an inorganic material and the second member is an organic resin. Moreover, it is preferable that the discharge side surface of the first member has water repellency.

  A manufacturing method of a nozzle plate for a liquid discharge head according to the present invention is a manufacturing method for manufacturing a nozzle plate for a liquid discharge head according to the present invention, and includes a step of etching and drilling a first member to form a hole. The first member is used as an etching mask, and the second member is perforated by etching to form a hole.

  Here, the etching of the first member and the second member is preferably performed by a dry etching method.

  The liquid discharge head according to the present invention includes the nozzle plate for a liquid discharge head according to the present invention.

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

  In the nozzle plate for a liquid ejection head according to the present invention, the diameter of the hole of the second member at the interface between the first member and the second member is larger than the diameter of the hole of the first member on the ejection surface side. Since it is configured to be large, the pressure loss is reduced and the droplet discharge efficiency is improved, and the center of the hole of the first member and the center of the hole of the second member are formed concentrically. Variations in the discharge direction can be reduced.

  A manufacturing method of a nozzle plate for a liquid discharge head according to the present invention is a manufacturing method for manufacturing a nozzle plate for a liquid discharge head according to the present invention, and includes a step of etching and drilling a first member to form a hole. Since the first member is used as an etching mask and the second member is perforated by etching to form a hole, the nozzle can be perforated in one step, and the droplet discharge efficiency is improved and the droplet is improved. A nozzle plate for a long head that reduces variations in the discharge direction can be accurately manufactured at low cost.

  Since the liquid discharge head according to the present invention includes the liquid discharge head nozzle plate according to the present invention, it is possible to improve the droplet discharge efficiency and reduce variations in the droplet discharge direction.

  Since the image forming apparatus according to the present invention includes the liquid discharge head according to the present invention, a high-quality image can be formed.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view showing an example of a liquid discharge head according to the present invention.
In this liquid discharge head, a laminated piezoelectric element 2 such as PZT is disposed on a frame support 1 made of resin or the like as a support. The multilayer piezoelectric element 2 is expanded and contracted by applying a droplet discharge drive voltage. Further, on the frame support 1, support columns 3 made of the same multilayer piezoelectric elements are arranged alternately with the multilayer piezoelectric elements 2. Since the driving voltage is not applied to the column 3, it functions as a simple column.

  A vibration plate 4 made of organic resin, metal, or a combination thereof is disposed on the piezoelectric element 2 and the support column 3, and on the vibration plate 4, a liquid chamber 6, a partition wall 7 between the liquid chambers, and not shown. The present invention has a laminated structure in which a flow path member 8 made of stainless steel or silicon having high rigidity for forming a common liquid chamber or the like is provided, and a nozzle 9 for discharging droplets is formed on the flow path member 8. A nozzle plate 10 is provided.

  The nozzle plate 10 communicates with the hole 11a of the first member 11 on the surface opposite to the droplet discharge direction of the first member 11 in which the hole 11a constituting the nozzle 9 for discharging the droplet is formed. A second member 12 having a hole 12a to be formed is provided. That is, on the flow path member 8, the second member 12 in which the hole 12a constituting the nozzle 9 is formed and the first member in which the hole 11a is also formed are laminated. The second member 12 has a thickness t <b> 2 and a nozzle diameter (diameter of the hole 12 a) d <b> 2 on the surface of the lamination interface with the first member 11. The first member 11 has a thickness t1 and a nozzle diameter (diameter of the hole 11a) d1 on the surface of the ejection surface. The thicknesses of the members 11 and 12 are in the relationship of t1 <t2, and the nozzle diameter is in the relationship of d1 <d2.

  Here, the second member 12 is formed of an organic resin film such as a polyimide film or polyethylene terephthalate (PET) film having a thickness t2 of 10 μm to 100 μm, preferably 20 μm to 50 μm, and the first member 11 is thick. A thickness t1 of 0.01 μm to 10 μm, preferably 0.05 μm to 1 μm, is formed of a material having selectivity when etching the hole 12a of the second member 12 such as a silicon oxide film or a metal film. Yes.

  The nozzle diameter d1 of the hole 11a formed in the first member 11 is 5 to 60 μm, preferably 10 to 30 μm, and the nozzle diameter d2 of the hole 12a formed in the second member 12 is the first. What is necessary is just to be larger than the nozzle diameter d1 of the hole 11a formed in the member 11. In this case, the difference between the nozzle diameters d1 and d2 is preferably 10 μm or less. If the difference is larger than that, the end of the nozzle formed on the first member 11 has a bowl shape, and this portion is likely to be damaged during liquid discharge, which may adversely affect the ejection characteristics.

  Further, the center of the hole 11 a formed in the first member 11 is formed to be concentric so as to coincide with the center of the hole 12 a formed in the second member 12. By forming the holes 11a and 12a of the first and second members 11 and 12 concentrically, it is possible to reduce variations in the droplet discharge direction.

  In addition, on the discharge side surface of the nozzle plate 10, a water-repellent material having a methyl group such as fluorine-based water-repellent film formation such as Optool (trade name) or silicone (trade name) in order to further stabilize the droplet discharge characteristics, etc. A water repellent layer 13 having water repellency to the liquid to be discharged is formed.

  The operation of the liquid discharge head configured as described above will be described. For example, in the case of driving by a pushing method, a pulse voltage is applied by selectively applying a drive pulse voltage of 20 to 50 V to the plurality of piezoelectric elements 2 according to an image recorded from a control unit (not shown). The piezoelectric element 2 is displaced to deform the diaphragm 4 toward the nozzle plate 10 and pressurize the liquid in the liquid chamber 6 by changing the volume (volume) of the liquid chamber 6. Is discharged. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, the application of voltage to the piezoelectric element 2 is turned off, so that the diaphragm 4 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. At this time, the liquid entered from the liquid supply pipe leading to a liquid tank (not shown) is filled in the liquid chamber 6, and droplets are ejected from the nozzle 9 in response to the next drive pulse application.

  Thus, in this liquid discharge head, the diameter of the hole of the second member at the interface between the first member and the second member is larger than the diameter of the hole of the first member on the discharge surface side. In addition, since the center of the hole of the first member and the center of the hole of the second member are formed concentrically, the nozzle plate is compared with the conventional nozzle plate configuration in which the thickness of the nozzle plate is equal. The fluid resistance of the entire nozzle plate when liquid passes is relatively small. As a result, pressure loss is reduced and efficient droplet discharge is possible, and variations in the liquid discharge direction are reduced. As a result, even when the liquid discharge head is a line-type head, it is possible to perform droplet discharge with good uniformity.

  Here, by making the thickness of the first member thinner than the thickness of the second member, the fluid resistance of the nozzle plate at the time of droplet discharge is smaller than that of a conventional nozzle plate configuration in which the nozzle plate has the same thickness. Further, the pressure loss is further reduced, and more efficient liquid discharge becomes possible, and the thickness of the first member is smaller than the thickness of the second member. The etching time is short and the dimensional accuracy is improved.

  Further, the first member is formed of a material having a relatively low etching rate with respect to the etchant used for etching the second member, so that the first member can be formed when etching the second member by etching. It can be used as an etching mask, it is not necessary to prepare a new etching mask, the process can be simplified, and the accuracy of the drilling process for the second member can be increased.

  Furthermore, the first member is made of an inorganic material, and the second member is made of an organic resin, so that a high etching selectivity can be obtained when the organic resin as the second member is perforated by etching, and the nozzle is highly accurate. Can be perforated.

  Further, by forming the water repellent layer on the discharge surface side surface of the first member, a stable meniscus surface is formed on the nozzle by the surface tension, so that stable droplet discharge characteristics can be obtained.

Next, a manufacturing process of the liquid discharge head including the manufacturing method of the nozzle plate for the liquid discharge head according to the present invention will be described with reference to FIGS.
First, as shown in FIG. 2A, a flow path member 8 such as SUS or silicon forming a liquid chamber or a liquid flow path is prepared, and as shown in FIG. Thus, the liquid chamber 6 and a flow path (not shown) are formed.

  Thereafter, as shown in FIG. 2C, an organic resin film 12A such as a polyimide film or a polyethylene terephthalate (PET) film is laminated and adhered as the second member 12 to the surface of the flow path member 8, and further, As shown in d), the organic resin film 12A such as a silicon oxide film or a metal film such as aluminum or nickel is etched on the organic resin film 12A as the second member by a sputtering method, a CVD method, a vacuum deposition method, or the like. The first member 11A, which is sometimes a material having selectivity, is formed. At this time, the first member 11A can be any material as long as it has an etching selectivity.

  Then, as shown in FIG. 5E, a positive or negative photosensitive resist 15 is formed on the first member 11A by a method such as spin coating or roll coating.

  Thereafter, as shown in FIG. 3A, the nozzle hole pattern is patterned on the resist 15 by ordinary photolithography, and the hole 11a is etched in the first member 11A using the resist pattern 15A as a mask. This etching process preferably uses a dry etching method having anisotropy using reactive ions by plasma excitation such as RIE, ICP, NLD, ECR, helicon, etc. in order to ensure dimensional accuracy.

  Next, as shown in FIG. 4B, the second member 12A is etched by using the resist pattern 15A and the hole 11a formed in the first member 11A as a mask, and the hole 12a is drilled. Also in this case, it is preferable to use a dry etching method using reactive ions by plasma excitation such as RIE, ICP, NLD, ECR, helicon, etc. in order to ensure dimensional accuracy.

  At this time, the hole 12a formed in the second member 12A is perforated so that the diameter d2 on the interface side with the first member 11A is larger than the diameter d1 of the hole 11a of the first member 11A. The center of the hole 11a of the first member 11A and the center of the hole 12a formed in the second member 12A are formed so as to be concentric. In normal dry etching, side etching occurs due to scattering of reactive ions or the like, and a size shift that is larger than the mask size usually occurs. Therefore, here, this condition may be used as it is, or It may be controlled so as to increase the difference between the diameters d1 and d2 by positively adjusting the etching conditions and increasing the dimensional shift. As described above, since the difference between the diameters d1 and d2 can be appropriately controlled as necessary, drilling by dry etching is particularly preferable.

  Next, as shown in FIG. 6C, a fluorine-based water repellent film such as Optool (trade name) or silicone (trade name) or the like is used to stabilize the droplet discharge characteristics on the surface of the first member 11A. A water repellent layer 13 having water repellency to the liquid to be discharged, such as a water repellent material having a methyl group, is formed. Further, as shown in FIG. 4D, the vibration plate 4, the piezoelectric element 2, the actuator 3 including the support 3 and the frame support 1, and the flow path member with the nozzle plate 10 manufactured up to the above-described steps. 8 is aligned and bonded to complete the liquid discharge head according to the present invention.

  As described above, the method includes the steps of etching and drilling the first member with an etching mask, and forming the hole by punching the first member with the etching mask and the first member as an etching mask. The nozzle holes can be drilled in one step, and a nozzle plate of a long head having a large size such as a line type head having a large number of nozzles can be easily manufactured with high accuracy and at low cost.

  In this case, the first member and the second member are not only drilled with high dimensional accuracy by using the dry etching method, but the first and second members are appropriately formed as necessary. The diameter difference of the hole of the member can be controlled.

Next, a specific first embodiment will be described with reference to FIG. In addition, the figure is sectional explanatory drawing of the Example.
Here, a liquid chamber 406 and a liquid chamber are formed on a SUS plate having a thickness of 200 μm on an actuator portion composed of a piezoelectric element 302 of PZT fixed to an ABS resin frame 301, a support portion 303, and a vibration plate 304 made of nickel. A SUS channel plate 308 having a partition wall 407 is provided, and a laminated nozzle plate 310 in which a silicon oxide film 311 having a thickness t1 = 0.2 μm is formed on a polyimide film 312 having a thickness t2 = 30 μm is provided as an SUS channel. It is provided on the plate 308.

  Here, the diameter (nozzle hole diameter) d1 of the hole 311a formed in the silicon oxide film 311 constituting the nozzle 309 is 26 μm, and the diameter (nozzle hole diameter) d2 of the hole 312a formed in the polyimide film 312 is 27 μm. Each drilling was performed by dry etching with oxygen plasma excited by a helicon wave to control the nozzle hole diameters d1 and d2.

  In such a liquid ejection head, the droplet ejection characteristics were evaluated by applying a drive voltage pulse to the piezoelectric element 302. As a comparison, when compared with the liquid discharge characteristics of a conventional liquid discharge head having the same nozzle diameter between the materials formed on the laminated nozzle plate, it was confirmed that the ejection voltage was lower than that of the conventional liquid discharge head. This shows that highly efficient liquid discharge with little pressure loss is possible.

Next, a specific second embodiment will be described with reference to FIG. In addition, the figure is sectional explanatory drawing of the Example.
Here, a liquid chamber 406 and a liquid chamber are formed on a SUS plate having a thickness of 200 μm on an actuator portion composed of a PZT piezoelectric element 402 fixed to an ABS resin frame 401, a support column 403, and a vibration plate 404 made of nickel. A SUS flow path plate 408 in which a partition wall 407 is formed is provided. A laminated nozzle plate 410 in which a silicon oxide film 411 having a thickness t1 = 0.2 μm is formed on a polyimide film 412 having a thickness t2 = 30 μm is provided on the SUS flow path plate 408.

  At this time, the diameter (nozzle hole diameter) d1 of the hole 411a formed in the silicon oxide film 411 constituting the nozzle 409 is 26 μm, and the diameter (nozzle hole diameter) d2 of the hole 412a formed in the polyimide film 412 is 27 μm. Each drilling was performed by dry etching with oxygen plasma excited by a helicon wave to control the nozzle hole diameters d1 and d2.

  Further, an optool (trade name) 413 is formed on the silicon oxide 411 constituting the nozzle plate 410 as a fluorine-based water repellent film with a thickness of 500 mm.

  In this liquid ejection head, a driving voltage pulse was applied to the piezoelectric element 402 to evaluate the droplet ejection characteristics. As a comparison, when compared with the droplet discharge characteristics of a conventional liquid discharge head having the same nozzle diameter between the materials formed on the laminated nozzle plate, it was confirmed that the jetting voltage was lowered. This shows that highly efficient liquid discharge with little pressure loss is possible. Further, it can be seen that a more stable liquid droplet discharge is possible by forming a fluorine-based water-repellent film on the silicon oxide 411 constituting the nozzle plate 410.

Next, a specific third embodiment will be described with reference to FIG. In addition, the figure is sectional explanatory drawing of the Example.
Here, a liquid chamber 506 and a liquid chamber are formed on a silicon wafer having a thickness of 400 μm on an actuator portion composed of a PZT piezoelectric element 502 fixed to an ABS resin frame 501, a support column 503, and a vibration plate 504 made of nickel. A silicon flow path plate 508 in which a partition wall 507 is formed is provided. A laminated nozzle plate 510 in which an Al film 511 having a thickness t1 = 0.5 μm is formed on a PET film 512 having a thickness t2 = 50 μm is provided on the silicon flow path plate 508.

  At this time, the diameter (nozzle hole diameter) d1 of the hole 511a formed in the Al film 511 constituting the nozzle 509 is 26 μm, and the diameter (nozzle hole diameter) d2 of the hole 512a formed in the PET film 512 is 30 μm. It is. Each drilling was performed by dry etching with oxygen plasma excited by a helicon wave to control the nozzle hole diameters d1 and d2.

  Further, on the Al film 511 constituting the nozzle plate 510, silicone (trade name) 513 is formed with a thickness of 1 μm as a methyl-based water-repellent film.

  In this liquid ejection head, a driving voltage pulse was applied to the piezoelectric element 502 to evaluate the droplet ejection characteristics. As a comparison, when compared with the droplet discharge characteristics of a conventional liquid discharge head in which the nozzle diameter is the same between the materials formed on the laminated nozzle plate, the fluid resistance of the entire nozzle plate 510 is lower than that in the first and second embodiments. Therefore, it was confirmed that the injection voltage was further lowered. This shows that highly efficient liquid discharge with less pressure loss is possible.

Next, a specific fourth embodiment will be described with reference to FIG. In addition, the figure is sectional explanatory drawing of the Example.
Here, an electrothermal conversion element 602 is provided on a silicon substrate 601, and PBO (polybenzoxazole), which is one of photosensitive polyimide resins that the electrothermal conversion element 602 faces, is patterned on the silicon substrate 601 to form a liquid. A flow path plate 608 in which a chamber 506 and a liquid chamber partition wall 507 are formed is provided. A laminated nozzle plate 610 in which an Al film 611 having a thickness t1 = 0.5 μm is formed on a polyimide film 612 having a thickness t2 = 20 μm is provided on the flow path plate 608.

  At this time, the diameter (nozzle hole diameter) d1 of the hole 611a formed in the Al film 611 constituting the nozzle 609 is 20 μm, and the diameter (nozzle hole diameter) d2 of the hole 612a formed in the polyimide film 612 is 24 μm. It is. Each perforation was performed by dry etching with oxygen plasma excited by ICP, and the nozzle hole diameters d1 and d2 were controlled.

  Further, a Ni-PTFE water-repellent film 613 is formed with a thickness of 1 μm on the Al film 611 constituting the nozzle plate 610 using the Al film 611 as an electrode.

  In this liquid discharge head, by applying a driving voltage pulse to the electrothermal conversion element 602, discharge energy due to film boiling is given to the liquid in the liquid chamber 606, and droplets are discharged from the nozzle 609. Therefore, the droplet discharge characteristics were evaluated by applying a driving voltage pulse to the electrothermal conversion element 602. As a comparison, when compared with the droplet discharge characteristics of a conventional liquid discharge head having the same nozzle diameter between the materials formed on the laminated nozzle plate, it was confirmed that the jetting voltage was lowered. This shows that highly efficient liquid discharge with little pressure loss is possible.

  Next, an example of the image forming apparatus according to the present invention provided with the liquid discharge head according to the present invention will be described with reference to FIGS. 8 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 9 is an explanatory plan view of a main part of the apparatus.

  In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown), and a driving pulley 106A is driven by a main scanning motor 104. 8 and the driven pulley 106 </ b> B through the timing belt 105 to move and scan in the direction indicated by the arrow (main scanning direction) in FIG. 8.

  For example, four independent ink jet recording liquid droplets (ink droplets) of black (K), cyan (C), magenta (M), and yellow (Y) are recorded on the carriage 103. The recording head 107 composed of the liquid ejection heads 107k, 107c, 107m, and 107y is arranged in a direction along the main scanning direction, and is mounted with the droplet ejection direction facing downward. In addition, although the independent liquid discharge head is used here, it is also possible to employ a configuration in which one or a plurality of heads having a plurality of nozzle rows for discharging recording liquid droplets of each color are used. Further, the number of colors and the arrangement order are not limited to this.

  As the liquid ejection head constituting the recording head 107, a diaphragm that forms the wall surface of the ink flow path is deformed by using an electromechanical conversion element such as a piezoelectric element as pressure generating means for pressurizing ink in the pressurized liquid chamber. A so-called piezo type that discharges ink droplets by changing the volume of the ink flow path, a so-called thermal type that utilizes film boiling of the recording liquid using an electrothermal transducer such as a heating resistor, The diaphragm and the electrode forming the wall surface are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the diaphragm and the electrode, thereby changing the volume of the ink flow path and discharging the ink droplets. An electric type, a shape memory alloy actuator using a metal phase change due to a temperature change, or the like can be used.

  The carriage 103 is equipped with a sub tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) (not shown) via an ink supply tube 109.

  On the other hand, as a sheet feeding unit for feeding a recording medium (sheet) 112 loaded on a sheet stacking unit (pressure plate) 111 such as a sheet feeding cassette 110, the sheets 112 are separated and fed from the sheet stacking unit 111 one by one. Opposite to the half-moon roller (feed roller) 113 and the feed roller 113 to be fed, a separation pad 114 made of a material having a large friction coefficient is provided, and this separation pad 114 is urged toward the feed roller 113 side.

  As a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 for electrostatically attracting and transporting the paper 112, and a paper feed unit A counter roller 122 for transporting the paper 112 fed through the guide 115 while sandwiching it between the transport belt 121 and the paper 112 fed substantially vertically upward is changed by about 90 ° and copied on the transport belt 121. A conveying guide 123 for adjusting the pressure and a tip pressure roller 125 urged toward the conveying belt 121 by a pressing member 124. In addition, a charging roller 126 that is a charging unit for charging the surface of the conveyance belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt, is stretched between the conveyance roller 127 and the tension roller 128, and the conveyance roller 127 is rotated from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133. By doing so, it is configured to circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 129 is disposed on the back side of the conveyance belt 121 in correspondence with the image forming area formed by the recording head 107.

  As shown in FIG. 9, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided. An encoder 136 is configured.

  The charging roller 126 is arranged so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121, and applies 2.5N to both ends of the shaft as a pressing force.

  Further, as shown in FIG. 8, an encoder scale 142 having slits is provided on the front side of the carriage 103, and an encoder sensor comprising a transmissive photosensor that detects the slits of the encoder scale 142 on the front side of the carriage 103. The encoder 144 for detecting the position of the carriage 103 in the main scanning direction is configured by these.

  Further, as a paper discharge unit for discharging the paper 112 recorded by the recording head 107, a separation unit for separating the paper 112 from the conveying belt 121, a paper discharge roller 152 and a paper discharge roller 153, and paper discharge A paper discharge tray 154 for stocking the paper 112 to be printed.

  A double-sided paper feeding unit 155 is detachably mounted on the back. The double-sided paper feeding unit 155 takes in the paper 112 returned by the reverse rotation of the transport belt 121, reverses it, and feeds it again between the counter roller 122 and the transport belt 121.

  Further, as shown in FIG. 9, a maintenance / recovery mechanism 156 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in the non-printing area on one side of the carriage 103 in the scanning direction.

  The maintenance / recovery machine 156 includes a cap 157 for capping each nozzle surface of the recording head 107, a wiper blade 158 which is a blade member for wiping the nozzle surface, and a discharge unit for discharging the thickened recording liquid. An empty discharge receiver 159 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording is provided.

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and includes the conveyance belt 121 and the counter roller 122. The leading end is guided by the conveying guide 123 and pressed against the conveying belt 121 by the leading end pressure roller 125, and the conveying direction is changed by approximately 90 °.

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

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103 in the forward and backward directions, ink droplets are ejected onto the stopped paper 112 to record one line, and the paper 112 is After transporting a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is finished and the paper 112 is discharged onto the paper discharge tray 54.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 112 is fed into the double-sided paper feeding unit 155 by rotating the conveyor belt 121 in the reverse direction. The paper 112 is reversed (with the back surface being the printing surface), and is fed again between the counter roller 122 and the conveyor belt 121. The timing is controlled, and the sheet is conveyed onto the conveyor bell 121 as described above. After recording on the back side, the sheet is discharged to the discharge tray 154.

  Further, during printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 155 side, and the nozzle surface of the recording head 107 is capped by the cap 157 so that the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped by the cap 157 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 158 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

  In the above embodiments, the printer configuration has been described as the image forming apparatus according to the present invention. However, the present invention is not limited to this, and can be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. Further, the present invention can be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.

FIG. 6 is an explanatory cross-sectional view showing an example of a liquid discharge head according to the present invention. FIG. 10 is an explanatory cross-sectional view illustrating the method for manufacturing the liquid discharge head. FIG. 3 is an explanatory cross-sectional view illustrating a process following FIG. 2. FIG. 3 is an explanatory cross-sectional view illustrating a first specific example of the liquid discharge head according to the present invention. FIG. 6 is a cross-sectional explanatory view showing a second specific example of the liquid ejection head according to the present invention. FIG. 10 is an explanatory cross-sectional view showing a third specific example of the liquid ejection head according to the present invention. FIG. 10 is an explanatory cross-sectional view showing a fourth specific example 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Frame 2 ... Piezoelectric element 4 ... Vibration plate 6 ... Liquid chamber 8 ... Flow path member 9 ... Nozzle 10 ... Nozzle plate 11 ... 1st member 12 ... 2nd member 13 ... Water-repellent layer 103 ... Carriage 107 ... Recording head

Claims (9)

  At least a second portion in which a hole communicating with the hole of the first member is formed on a surface opposite to the droplet discharge direction of the first member in which the hole constituting the nozzle for discharging the droplet is formed. In the nozzle plate for a liquid discharge head provided with the above-mentioned member, the diameter of the hole of the second member at the interface between the first member and the second member is on the discharge surface side of the hole of the first member. A nozzle plate for a liquid discharge head, wherein the nozzle plate is larger than the diameter, and the center of the hole of the first member and the center of the hole of the second member are formed concentrically.   2. The nozzle plate for a liquid discharge head according to claim 1, wherein the thickness of the first member is thinner than the thickness of the second member.   3. The liquid ejection head nozzle plate according to claim 1, wherein the first member has a relatively low etching rate relative to an etchant used for etching the second member. 4. Nozzle plate for head.   4. A nozzle plate for a liquid discharge head according to claim 1, wherein the first member is an inorganic material and the second member is an organic resin. Nozzle plate.   5. The nozzle plate for a liquid discharge head according to claim 1, wherein the discharge side surface of the first member has water repellency.   A manufacturing method for manufacturing a nozzle plate for a liquid discharge head according to any one of claims 1 to 5, wherein a step of etching and drilling the first member to form a hole portion; A method for manufacturing a nozzle plate for a liquid discharge head, comprising: forming a hole by punching a second member by etching as an etching mask.   7. The method for manufacturing a nozzle plate for a liquid discharge head according to claim 6, wherein the etching of the first member and the second member is performed by a dry etching method.   6. A liquid discharge head for discharging liquid droplets of a recording liquid, comprising the nozzle plate for a liquid discharge head according to any one of claims 1 to 5. 9. An image forming apparatus comprising a liquid discharge head for discharging recording liquid droplets to form an image, wherein the liquid discharge head is the liquid discharge head according to claim 8.

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