JP5896275B2 - Droplet discharge head and image forming apparatus - Google Patents

Description

  The present invention relates to a droplet discharge head that generates pressure fluctuations in an individual liquid chamber and discharges liquid from nozzles formed in the individual liquid chamber, and an image forming apparatus equipped with the droplet discharge head.

  In general, a printer, a fax machine, a copier, a plotter, or an image forming apparatus that combines a plurality of these functions includes, for example, a liquid ejection head that ejects ink droplets, and ejects ink droplets while conveying a medium. There is an ink jet recording apparatus that forms an image by adhering to a medium. The medium here is also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, a recording paper, and the like are also used synonymously. 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. The image formation is not only giving an image having a meaning such as a character or a figure to the medium but also giving an image having no meaning such as a pattern to the medium (simply ejecting a droplet). Also means. The ink is not limited to so-called ink, and is not particularly limited as long as it becomes liquid when ejected. For example, the ink is a generic term for liquids including DNA samples, resists, pattern materials, and the like. Use.

  An ink jet head (hereinafter referred to as a recording head) mounted on the ink jet recording apparatus includes an individual liquid chamber that communicates with a nozzle that ejects ink droplets, and a pressure generating unit that generates a pressure change in the individual liquid chamber. Has been. A plurality of pressure generating means have been put into practical use and commercialized. Examples include a thermal ink jet method that uses a pressure fluctuation by vaporizing a liquid by installing a heater in the individual liquid chamber, and a method that changes the pressure in the individual liquid chamber by installing an actuator in the individual liquid chamber. Among these, the method using an actuator includes, for example, a piezoelectric element method and an electrostatic method depending on the type of the actuator. Among the methods using the actuator, the piezoelectric element method discharges ink droplets from the nozzles by deforming and displacing a vibration plate constituting a part of the individual liquid chamber using the piezoelectric element. The piezoelectric element is formed by laminating a common electrode, a piezoelectric body, and individual electrodes. While this piezoelectric element system can cope with ink having a wide range of physical properties, it is required to increase the density of the liquid chamber arrangement and to reduce the size of the recording head. These requirements can be achieved by using a MEMS (Micro Electro Mechanical Systems) process. Specifically, a unimorph type piezoelectric actuator unit in which a common electrode, a piezoelectric body, an individual electrode, and the like are laminated on a vibration plate constituting a part of an individual liquid chamber using a thin film forming process which is one of MEMS processes. Is provided. Then, using a semiconductor device manufacturing process (hereinafter referred to as a thin film process) which is one of the MEMS processes, the common electrodes of the individual piezoelectric elements and the wirings from the individual electrodes are patterned. As a result, it is possible to achieve a higher density of the liquid chamber arrangement and a smaller recording head.

  By increasing the density and reducing the size in this way, the number and density of nozzle arrays per head can be increased, the number of ejected dots per scan can be increased, and the printing speed can be increased. And the number of nozzle arrays per head increases, and the number of piezoelectric elements also increases. In the case of such a recording head having a large number of arrangements, since the recording density is increased, a method of drawing out common electrode wirings electrically connected to the common electrodes from both ends of the head in the arrangement direction of the piezoelectric elements is generally used. Each common electrode wiring drawn out from both ends of the head is grounded, for example, in order to make a driving voltage applied between the individual electrode and the common electrode of the piezoelectric element a predetermined potential difference. When the resistance of the common electrode wiring is high, a voltage drop due to the common electrode wiring increases from the both ends of the head toward the center in the arrangement direction of the piezoelectric elements. In the central piezoelectric element, the voltage drop due to the common electrode wiring is large, so that the voltage value is lower than the voltage value of the predetermined drive voltage. For this reason, a sufficient driving voltage is not applied to the piezoelectric element corresponding to the nozzle near the center in the arrangement direction of the piezoelectric elements of the recording head, and the deformation displacement amount of the piezoelectric body becomes unstable, and the droplet discharge is not performed. Uniformity deteriorates.

  On the other hand, when the common electrode wiring is formed by using the thin film process, it is difficult to form a thick film because a metal or an alloy is formed by a sputtering method, a CVD method, or the like. Specifically, it is difficult to obtain a film thickness of 5 [μm] or more. Generally, it is necessary to set the film thickness to 1 [μm] or less from the viewpoint of film stress and manufacturing efficiency (process time). It is said that. For this reason, it is necessary to increase the cross-sectional area of the common electrode wiring in order to reduce the resistance of the common electrode wiring when the thin film process is used. As a result, the common electrode wiring is widened, the head size is increased, the number of chips acquired per wafer is reduced, and this causes an increase in cost. For this reason, a method for reducing the resistance of the common electrode wiring using the thin film process is required.

  As a droplet discharge head for reducing the resistance of the common electrode wiring by using this thin film process, the one described in Patent Document 1 is known. The droplet discharge head of Patent Document 1 includes a nozzle plate having a plurality of nozzles that discharge liquid, and a liquid chamber substrate that is stacked on the nozzle plate and forms a plurality of individual liquid chambers that communicate with the nozzles. ing. A diaphragm is formed on a part of the inner wall of the individual liquid chamber. The vibration plate is provided with a piezoelectric actuator section having a plurality of piezoelectric bodies for boosting each individual liquid chamber, and a common electrode and individual electrodes provided so as to sandwich the piezoelectric bodies. A driving voltage is applied between the common electrode and the individual electrode of the piezoelectric actuator unit by a driving voltage applying unit. The common electrode is made of Pt having a low resistivity. A first common electrode wiring made of a material different from Pt is arranged on the common electrode through the insulating layer, and the first common electrode wiring is shared through the contact hole for the common electrode opened in the insulating layer. It is electrically connected to the electrode. Since the first common electrode wiring is composed of the same layer as the individual electrode wiring drawn from the piezoelectric element, it cannot be made thick. Therefore, in the droplet discharge head disclosed in Patent Document 1, the second common electrode wiring which is another wiring is stacked on the first common electrode wiring. As a result, the total cross-sectional area of the first common electrode wiring and the second common electrode wiring is increased, and the resistance of the common electrode wiring is greatly reduced.

  Then, when the second common electrode wiring is stacked on the first common electrode wiring, the first common electrode wiring and the common electrode contract due to a temperature change during the stacking process. Since the shrinkage rates of the first common electrode wiring and the common electrode at this time are different, stress is generated inside each layer of the first common electrode wiring and the common electrode, and the first common electrode in the contact hole There is a possibility that peeling occurs at the interface between the wiring and the common electrode. Therefore, in the droplet discharge head of Patent Document 1, contact holes are provided at a plurality of locations in the longitudinal direction of the first and second common electrode wirings, and the common electrode and the first common electrode wiring in each contact hole are provided. The contact area is kept small. This suppresses the stress generated in each layer of the first common electrode wiring and the common electrode, and prevents the occurrence of peeling at the interface between the first common electrode wiring and the common electrode in each contact hole. doing.

  FIG. 11 is a plan view of a part of the configuration of the recording head under development by the present applicant, and FIG. 12 is a cross-sectional view taken along the line A-A 'of FIG. In the recording head 500 under development by the present applicant, the first common electrode wiring 514 corresponding to the first common electrode wiring of Patent Document 1 is stacked on the common electrode 512 in the arrangement direction of the piezoelectric bodies 516. . A second common electrode wiring 518 corresponding to the second common electrode wiring of Patent Document 1 is stacked on a part of the first common electrode wiring 514. The width of the first common electrode wiring 514 in the short direction is wider than the width of the second common electrode wiring 518 in the short direction. Contact holes 520 are provided in a plurality of locations in the short direction of the first common electrode wiring 514. As a result, even in the recording head under development, the resistance of the entire common electrode wiring is reduced.

  In the recording head 500 under development, the nozzle plate 503, the flow path substrate 502, the vibration plate 501, the common electrode 512, the piezoelectric body 516, the individual electrode 511, the holding substrate 504, and the common liquid chamber substrate 505 are joined in this order. doing. By joining the plate-like members in this way, an individual liquid chamber 509, an individual liquid chamber 509, an ink supply port 507, and a common liquid chamber 506 communicating with the nozzle 510 are formed. The nozzle 510 communicates with the individual liquid chamber 509 with pressure generated by driving a piezoelectric element formed on the vibration plate 501 of the individual liquid chamber 509 and including the piezoelectric body 516, the individual electrode 511, and the common electrode 512. Ink is ejected. The piezoelectric element is driven by being connected to the driving IC 515 at the point where the piezoelectric element is drawn from the individual electrode 511 and the common electrode 512 using the individual electrode wiring 513 and the first common electrode wiring 514, respectively.

  As shown in FIG. 12, the second common electrode wiring 518 is installed in the cavity of the concave portion 523 of the holding substrate 504 provided above the first common electrode wiring 514. The space of the concave portion 523 of the holding substrate 504 has a structure that becomes narrower upward. That is, the height of the central space in the direction orthogonal to the arrangement direction of the nozzles of the holding substrate 504 is higher than the heights on both sides. For this reason, the second common electrode wiring 518 is laminated on the first common electrode wiring 514 with a thickness of, for example, 10 [μm]. Therefore, in order to prevent the second common electrode wiring 518 from contacting the wall surface of the holding substrate 504, A second common electrode wiring 518 is stacked in the center direction in the short direction of the first common electrode wiring 514 having a high height so as to extend in the nozzle arrangement direction.

  In the recording head under development having such a configuration, the stress generated by the temperature change during the stacking process is caused by contact holes (in the first common electrode wiring 514 formed by stacking the second common electrode wiring 518 ( It was found that it was concentrated in the first common electrode wiring 514 at 520 (hereinafter referred to as the first contact hole). Since the first contact hole 520 is provided, the contact hole (hereinafter referred to as the second contact hole) provided in the portion of the first common electrode wiring 514 where the stress is not stacked on the second common electrode wiring 518 is provided. (Referred to as a contact hole) 520. For this reason, the stress generated in the first common electrode wiring 514 in the second contact hole 520 is reduced. However, once peeling occurs at the interface between the first common electrode wiring 514 and the common electrode 512 in the first contact hole 520, the stress propagates to the second contact hole 520 at once. It was also found that the impact caused by the propagation of the stress easily causes separation at the interface between the first common electrode wiring 514 and the common electrode 512 in the second contact hole 520.

  The present invention has been made in view of the above problems, and its purpose is to achieve both liquid resistance reduction of the common electrode wiring and suppression of occurrence of peeling at the interface between the common electrode and the common electrode wiring. It is an object to provide a droplet discharge head and an image forming apparatus capable of improving the uniformity of droplet discharge.

In order to achieve the above object, a nozzle plate having a plurality of nozzles for discharging liquid, a liquid chamber substrate stacked on the nozzle plate and forming a plurality of individual liquid chambers respectively communicating with the nozzles, and the individual liquid A plurality of piezoelectric bodies that pressurize each individual liquid chamber via a diaphragm that constitutes a part of the chamber, a piezoelectric actuator unit having a common electrode and an individual electrode provided so as to sandwich the piezoelectric body, and A driving voltage applying unit that applies a driving voltage between the common electrode and the individual electrode; a first common electrode wiring that electrically connects the common electrode and the driving voltage applying unit; A second common electrode wiring layered on the common electrode wiring layer, and the first common electrode wiring layer including the first common electrode wiring layer on which the second common electrode wiring layer is stacked has a plurality of contact holes. Before Connected to a common electrode, and applying the drive voltage between the common electrode and the individual electrode by the drive voltage applying means, the piezoelectric body is deformed and displaced, and the diaphragm is deformed and displaced, in the droplet discharge head for discharging liquid droplets from the nozzle by the pressure of the individual liquid chamber is changed, and laminating the second common electrode wiring on a portion of the first common electrode line, the The second common electrode wiring is formed in a substantially central portion of the first common electrode wiring in a direction that is continuous in the nozzle arrangement direction and perpendicular to the nozzle arrangement direction, and the contact hole The second common electrode wiring is formed on both sides of the stacked first common electrode wiring.

In the present invention, since the second common electrode wiring is stacked on the first common electrode wiring, the resistance of the common electrode wiring can be reduced in the same manner as the droplet discharge head of Patent Document 1.
Then, the second common electrode wiring in which stress generated due to the difference in contraction rate between the first common electrode wiring and the common electrode due to the temperature change during the stacking process is concentrated due to the lamination process. The common electrode contact hole provided in the portion of the first common electrode wiring laminated is formed on both sides of the first common electrode wiring laminated with the second common electrode wiring . For this reason, the stress is dispersed on the average inside the first common electrode wiring in each common electrode contact hole. As a result, the stress dispersed on average in each common electrode contact hole is applied to the common electrode contact hole provided in the portion of the first common electrode wiring in which the second common electrode wiring as in Patent Document 1 is stacked. The stress is intensively generated inside the first common electrode wiring in FIG. Therefore, peeling at the interface between the common electrode and the first common electrode wiring in each common electrode contact hole can be suppressed. Thereby, it is possible to improve the uniformity of droplet discharge by satisfying both the reduction in the resistance of the common electrode wiring and the suppression of the occurrence of peeling at the interface between the common electrode and the common electrode wiring.

  According to the present invention, it is possible to improve the uniformity of droplet discharge by simultaneously reducing the resistance of the common electrode wiring and suppressing the occurrence of peeling at the interface between the common electrode and the common electrode wiring. Effects can be obtained.

It is the schematic explaining the whole structure of the mechanism part of this inkjet recording device. It is a principal part top view of the mechanism part of this inkjet recording device. It is a schematic block diagram of the whole another mechanism part of this inkjet recording device. FIG. 2 is a plan view illustrating a configuration of a part of a recording head of the inkjet recording apparatus. FIG. 5 is a cross-sectional view taken along line A-A ′ of FIG. 4. It is sectional drawing of the nozzle arrangement direction of a single chamber liquid chamber. It is sectional drawing of the nozzle arrangement direction of an ink supply path. It is a top view which shows the structure of the modification of the recording head of this inkjet recording device. FIG. 7 is a cross-sectional view taken along line A-A ′ of FIG. 6. It is a top view which shows the structure of another modification of the recording head of this inkjet recording device. FIG. 6 is a plan view of a partial configuration of a recording head under development. It is A-A 'line sectional drawing of FIG.

Hereinafter, a configuration example of an ink jet recording apparatus as an example of an image forming apparatus including a liquid ejection head according to an embodiment of the present invention will be described.
FIG. 1 is a schematic diagram for explaining the overall structure of a mechanism portion of the ink jet recording apparatus, and FIG. 2 is a plan view of a principal portion of the mechanism portion.
This ink jet recording apparatus is a serial type ink jet recording apparatus, and a carriage 233 is slidably held in a main scanning direction by a main guide rod 231 and a sub guide rod 232 which are guide members horizontally mounted on left and right side plates 221A and 221B. To do. Then, the main scanning motor (not shown) moves and scans in the direction indicated by the arrow (carriage main scanning direction) in FIG. 2 via the timing belt. The carriage 233 is equipped with a liquid ejection head unit for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). In this droplet discharge head unit, the recording head 234 is arranged in a sub-scanning direction perpendicular to the main scanning direction with a nozzle row composed of a plurality of nozzles, and the ink droplet discharging direction is directed downward. The recording head 234 is configured by attaching liquid ejection heads 234a and 234b each having two nozzle rows to one base member. Then, one nozzle row of one head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and one nozzle row of the other head 234b has magenta (M) droplets. Droplets are discharged, and the other nozzle row discharges yellow (Y) droplets. Here, the two-head configuration is configured to eject droplets of four colors, but a liquid ejection head for each color can also be provided. The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 235” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridge 210 of each color by the supply unit 224 via the supply tube 236 of each color.

  On the other hand, as a paper 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. Paper roller) 243 and paper feed roller 243. A separation pad 244 made of a material having a large friction coefficient is provided, and the separation pad 244 is urged toward the paper feed roller 243 side. A sheet 242 fed from the sheet feeding unit is fed to the lower side of the recording head 234. For this purpose, a guide member 245 for guiding the paper 242, a counter roller 246, a conveyance guide member 247, and a pressing member 248 having a tip pressure roller 249 are provided. In addition, a transport belt 251 serving as a transport unit for electrostatically attracting the fed paper 242 and transporting the paper 242 at a position facing the recording head 234 is provided. 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. ing. 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 receptacle 288 is arranged. The idle discharge receiver 288 includes an opening 289 along the nozzle row direction of the recording head 234. In the 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. Then, the paper is sandwiched between the transport belt 251 and the counter roller 246 and transported. Further, the front end is guided by the transport guide 237 and pressed against the transport belt 251 by the front end pressure roller 249, and the transport direction is changed by approximately 90 °. The At this time, an alternating voltage is applied to the charging roller 256 so that a positive output and a negative output are alternately repeated. In this case, a positive voltage and a negative voltage are alternately charged in a band shape with a predetermined width in a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251. Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203. As described above, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, it is possible to perform highly reliable and stable droplet discharge and form a high-quality image at high speed. can do.

  Next, another configuration example of the ink jet recording apparatus as an example of an image forming apparatus including the liquid ejection head according to the embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram of another entire mechanism unit of the ink jet recording apparatus. This ink jet recording apparatus is a line type ink jet recording apparatus, and 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, and a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405. Thereafter, the paper 403 is discharged onto a paper discharge tray 406 attached to the side of the apparatus main body 401. In addition, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided. When performing double-sided printing, after the one-side (front) printing is completed, the paper 403 is taken into the double-sided unit 407 while being conveyed in the reverse direction by the conveyance mechanism 405. Then, the sheet is reversed and sent to the transport mechanism 405 again with the other side (back side) as a printable side, and the paper 403 is discharged to the 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.

  Also, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (hereinafter referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) for maintaining and recovering the performance of the recording head is provided corresponding to each recording head 411. During the head performance maintenance operation such as purge processing and 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. Let Here, the recording head 411 is arranged to eject droplets of each color in the order of blank, 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 recording head, one or a plurality of recording heads provided with a plurality of nozzle rows for discharging droplets of each color at predetermined intervals can be used. Further, the recording head and the recording liquid cartridge that supplies ink to the recording head can be integrated or separated. The sheets 403 in the sheet feed tray 404 are separated one by one by a sheet feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401. Then, the sheet is fed between the registration roller 425 and the conveyance belt 433 along the guide surface 423a of the conveyance guide member 423, and is conveyed to the conveyance belt 433 of the conveyance mechanism 405 through 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 transport mechanism 405 includes a transport belt 433, a charging roller 434, a plantain member 435, and a pressing roller 436. The conveyance belt 433 is an endless conveyance belt that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432. The charging roller 434 is a charging roller for charging the conveyance belt 433. The platen member 435 is a member that maintains the flatness of the transport belt 433 at a portion facing the image forming unit 402. The holding roller 436 presses the sheet 403 fed from the conveying belt 433 against the conveying roller 431 side. Although not shown in the drawings, a cleaning roller made of a porous material or the like, which is a cleaning means for removing ink attached to the conveyance belt 433, is also provided. 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 transport belt 433 moves in the direction indicated by the arrow and is charged by coming into contact with the charging roller 434 to which a high potential applied voltage is applied. When the paper 403 is fed onto the conveyance belt 433 charged to this high potential, the paper 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 sheet 403 is moved around the conveyor belt 433, and droplets are ejected from the recording head 411. As a result, a required image is formed on the sheet 403, and the sheet 403 on which the image is recorded is discharged to the discharge tray 406 by the discharge roller 438.

  Thus, in this ink jet recording apparatus, it is possible to improve the uniformity of droplet discharge by reducing the resistance of the common electrode and suppressing delamination as will be described later. In the above embodiment, the droplet discharge head according to the present invention is applied to an inkjet head. However, a droplet discharge head for discharging a liquid droplet other than ink, for example, a liquid resist for patterning, a droplet discharge for discharging a gene analysis sample. It can also be applied to heads.

  Next, the configuration of the droplet discharge head of this embodiment will be described. 4 is a plan view showing a configuration of a part of a recording head of the ink jet recording apparatus, and FIG. 5 is a cross-sectional view taken along line A-A ′ of FIG. 4. FIG. 6 is a cross-sectional view of the individual chamber liquid chamber in the nozzle arrangement direction. FIG. 7 is a cross-sectional view of the ink supply path in the nozzle array direction. In a recording head 500 as a droplet discharge head, a flow path substrate 502 is bonded to the lower surface of the vibration plate 501, and a nozzle plate 503 is bonded to the lower surface of the flow path substrate 502. Then, the holding substrate 504 and the common liquid chamber substrate 505 are stacked on the vibration plate 501 and the flow path substrate 502 to form an ink flow path. An ink supply port 507 that opens to the flow path substrate 502 via a common liquid chamber (holding substrate 504, common liquid chamber substrate 505) 506 in which ink from an ink tank (not shown) communicates with the ink tank, ink supply It is supplied to the channel 508 and the individual liquid chamber 509. Ink is ejected from a nozzle 510 communicating with the individual liquid chamber 509 with pressure generated by driving a piezoelectric element formed on the vibration plate 501 of the individual liquid chamber 509 and including the piezoelectric body 516, the individual electrode 511, and the common electrode 512. Discharge. The piezoelectric element is driven by being connected to the driving IC 515 at the point where the piezoelectric element is drawn from the individual electrode 511 and the common electrode 512 using the individual electrode wiring 513 and the first common electrode wiring 514, respectively.

  The nozzle plate 503 is a substrate on which ink ejection nozzles 510 are arranged, and any material can be used from the required rigidity and workability. Examples include metals or alloys such as SUS and nickel, inorganic materials such as silicon and ceramics, and resin materials such as polyimide. The processing method of the nozzle can be selected from material characteristics, required accuracy, and workability, and examples include electroforming plating method, etching method, press processing method, laser processing method, photolithography method, etc. . The nozzle aperture diameter, the number of arrays, and the array density can be set to an optimum combination in accordance with the specifications required for the ink head.

In addition, an ink supply port 507, an ink supply path 508, and an individual liquid chamber 509 are formed in the flow path substrate 502. Any substrate material can be used from the viewpoint of workability and physical properties. However, it is preferable to use a silicon substrate capable of using a photolithography method at 300 [dpi] (about 85 [μm] pitch) or more. Any processing of the liquid chamber can be used, but when the above-described photolithography method is used, either a wet etching method or a dry etching method can be used. In any method, since the liquid chamber side of the diaphragm is made of a silicon dioxide film or the like, an etch stop layer can be formed, so that the height of the liquid chamber can be controlled with high accuracy. The individual liquid chamber 509 has a function of applying a pressure to the ink and discharging a droplet from the nozzle 510. A vibration plate 501 is formed above the individual liquid chamber 509, and a piezoelectric element in which the common electrode 512, the piezoelectric body 516, and the individual electrode 511 are stacked is formed on the vibration plate 501. Although any diaphragm 501 can be used, it is preferable to use a material having high rigidity such as silicon, nitride, oxide, or carbide. Alternatively, a stacked structure of these materials may be used. In the case of a laminated film, it is preferable that the residual stress is reduced in consideration of the internal stress of each material. For example, in the case of stacking Si ₃ N ₄ and SiO _2, a configuration in which Si ₃ N _{4 serving as} tensile stress and SiO _{2 serving} as compressive stress are alternately stacked to relieve the stress is given as an example. The thickness of the diaphragm 501 can be selected according to desired characteristics, but is preferably in the range of about 0.5 [μm] to 10 [μm], more preferably in the range of 1.0 to 5.0 [μm]. It is. If the diaphragm is too thin, the diaphragm is likely to be damaged due to cracks or the like, and if it is too thick, the amount of displacement becomes small and the discharge efficiency is lowered. Moreover, when too thin, the natural frequency of a diaphragm will fall and the subject that a drive frequency cannot be raised occurs.

  Further, the common electrode 512 and the individual electrode 511 can be made of any conductive material. Examples include metals, alloys, and conductive compounds. A single layer film or a laminated film of these materials may be used. Furthermore, since it is necessary to select a material that does not react or diffuse with the piezoelectric body 516, it is necessary to select a highly stable material. In addition, an adhesion layer may be formed in consideration of adhesion between the piezoelectric body 516 and the diaphragm 501 as necessary. Examples of the electrode material include Pt, Ir, Ir oxide, Pd, Pd oxide and the like as highly stable materials. Further, examples of the adhesion layer with the diaphragm 501 include Ti, Ta, W, and Cr. As the piezoelectric material, a ferroelectric material exhibiting piezoelectricity can be used. As examples, lead zirconate titanate and barium titanate are generally used. Arbitrary methods can be used as the method for forming the piezoelectric body, and examples thereof include a sputtering method and a sol-gel method, and the sol-gel method is preferable because the film forming temperature is low. The upper electrode and the piezoelectric body need to be patterned for each individual liquid chamber. For patterning, a normal photolithography method can be used. Also, when the piezoelectric film is formed by the sol-gel method, a spin coating method or a printing method can also be used. The piezoelectric element including the piezoelectric body 516, the individual electrode 511, and the common electrode 512 needs to be formed in the upper part of the individual liquid chamber 509. When formed on the partition wall that divides the individual liquid chamber 509, the partition wall impedes deformation of the diaphragm, which causes a decrease in discharge efficiency or damage to the piezoelectric element due to stress concentration.

  In addition, an ink supply path 508 is formed in the flow path substrate 502 so as to communicate with the individual liquid chamber 509. The ink supply path 508 has a function of supplying ink from the common liquid chamber 506 to the individual liquid chamber 509. Furthermore, the ink supply path 508 has a function as a fluid resistance section that prevents back flow of ink by the pressure generated in the individual liquid chamber 509 by driving the piezoelectric element and discharges it from the nozzle. Therefore, it is necessary to reduce the cross-sectional area of the individual liquid chamber 509 in the ink flow direction and increase the fluid resistance. The height of the ink supply path needs to be substantially the same as that of the individual liquid chamber 509. When silicon is used for the flow path substrate 502 and the individual liquid chamber 509 and the ink supply path 508 are formed using a photolithography method (+ etching), there is an advantage that processing can be performed under the same conditions as the individual liquid chamber 509. By making the height of the ink supply path 508 lower than that of the individual liquid chamber 509, the fluid resistance can be increased. In order to increase the fluid resistance, it is necessary to control the over-etching amount of the individual liquid chambers by time management. Therefore, the fluid resistance cannot be made uniform due to variations in the etching rate. As a result, the discharge uniformity is deteriorated. On the other hand, when the ink supply path 508 is the same as the height of the individual liquid chamber 509, the upper part of the ink supply path 508 becomes a vibration plate without a piezoelectric element, which becomes a compliance component and lowers the discharge efficiency.

  Further, as described above, since the height of the ink supply path 508 is substantially the same as that of the individual liquid chamber 509, it is necessary to reduce the width of the ink supply path 508 in order to increase the fluid resistance. When the width of the ink supply path 508 is narrowed, the cross-sectional shape (particularly near the diaphragm) tends to become unstable. Therefore, the diaphragm compliance value on the ink supply path tends to vary. Therefore, by forming a laminated film on the ink supply path, the rigidity is increased, and the compliance value and its variation are reduced to reduce the discharge variation. The laminated film on the ink supply path will be described in the later-described common electrode wiring configuration. The ink supply path 508 communicates with the common liquid chamber 506 through the ink supply path 508 in which the vibration plate 501 is opened.

  The individual liquid chambers 509 are arranged as ink jet heads by arranging them in the nozzle arrangement direction via partition walls. As shown in FIG. 4, the individual liquid chamber 509 is partitioned by a partition wall 527, and a piezoelectric element is formed in each of the partition chambers. The height of the individual liquid chamber 509 can be arbitrarily set from the head characteristics, but is preferably in the range of 20 to 100 [μm]. The partition walls 527 between the individual liquid chambers can be arbitrarily set in accordance with the arrangement density, but the partition wall width is preferably 10 to 30 [μm]. Further, when the partition wall width is narrow, when the piezoelectric elements of the adjacent individual liquid chambers are driven, mutual interference occurs between the adjacent liquid chambers, and the discharge variation becomes large. When narrowing the partition wall width, it is possible to reduce the height of the liquid chamber.

  In order to input a drive signal to the arranged piezoelectric elements, the individual electrode wiring 513 is drawn from the individual electrode 511 and the first common electrode wiring 514 is drawn from the common electrode 512. The individual electrodes 511 arranged are led out to the individual electrode pads 517 through the individual electrode wirings 513. The common electrode 512 extends to the ink supply path before the ink supply port on the side opposite to the individual electrode pad 517, and is drawn out to the common electrode wiring 518 through the first common electrode wiring 514 that is electrically connected to the common electrode 512. An insulating film 519 is formed between the common electrode 512 and the first common electrode wiring 514 and is electrically connected through a contact hole 520 opened in the insulating film 519. The individual electrode wiring 513 is drawn out to the individual electrode pad 517, and the first common electrode wiring 514 is drawn out to the common electrode pad 525, and is connected to the driving IC 515 through the opening of the holding substrate 504. Further, by stacking the common electrode wiring 518 that is electrically connected to the first common electrode wiring 514 on the ink supply path, the electrical resistance of the entire common electrode wiring is reduced.

The individual electrode wiring 513 and the first common electrode wiring 514 are preferably formed using the same material and the same process. As the electrode material, a metal, an alloy, or a conductive material having a low resistance value can be used. In addition, it is necessary to use the individual electrode 511 and the common electrode 512 and a material having low contact resistance. Examples include Al, Au, Ag, Pd, Ir, W, Ti, Ta, Cu, Cr, and the like, and a stacked structure of these materials may be used in order to reduce contact resistance. As a material for reducing the contact resistance, any conductive compound may be used. Examples include oxides and nitrides such as Ta ₂ O ₅ , TiO ₂ , TiN, ZnO, In ₂ O ₃ , SnO, and composite compounds thereof. The film thickness can be arbitrarily set, but is preferably 1 [μm] or less. In addition, it is preferable to employ a film forming method with high film thickness uniformity such as a vacuum film forming method. Since these electrodes serve as a joint surface with a holding substrate, which will be described later, it is necessary to adopt a film thickness method and a film forming method that can ensure height uniformity.

  In addition, the second common electrode wiring 518 has a function of reducing the resistance value of the common electrode 512. As shown in FIG. 4, the individual liquid chambers 509 and the piezoelectric elements are stacked on the common electrode 512 in the arrangement direction. Since the first common electrode wiring 514 and the second common electrode wiring 518 need to be conductive, it is necessary to use a combination of materials having low contact resistance. Although any material can be used as the material of the second common electrode wiring 518, it is necessary to use a metal, an alloy, or a conductive compound having a small specific resistance. Moreover, since it is necessary to increase the film thickness in order to reduce the resistance in a small area on the substrate, it is necessary to select a material and a method for forming the thick film. As a film thickness, 10-100 [micrometer] is preferable, More preferably, it is 10-50 [micrometer]. Examples of the process capable of forming a thick film include an electrolytic plating method, an electroless plating method, and a screen printing method. Examples of the electrode material capable of forming these thick films include Au, Ag, Cu, Ni, Cr, and the like and alloys containing them. In addition, it is preferable to select a film formation method or material having a small residual stress after film formation. By forming the second common electrode wiring 518, even when the second common electrode wiring 518 is taken out from the end in the arrangement direction of the individual liquid chambers 509, a voltage drop due to the distance from the taking-out portion is less likely to occur. Thus, it is possible to improve the discharge uniformity.

  An individual electrode pad 517 and a common electrode pad 525 are formed on the individual electrode 511 and the common electrode 512 drawn to the opening of the holding substrate 504. A wiring 521 for inputting a signal from the driving IC 515 is connected to each of these pads. An arbitrary method can be used for the connection of the wiring 521, and examples thereof include an ACF bonding using FPC, a solder bonding, a wire bonding method, and a flip chip method for directly bonding to the output terminal 526 of the driving IC. It is necessary to select the material and structure of the pad portion according to each bonding method.

As described above, since the flow path substrate 502 has a thickness of 20 to 100 [μm], the holding substrate 504 is bonded to the side facing the nozzle plate 503 in order to ensure the rigidity of the flow path substrate 502. Although any material can be used for the holding substrate 504, it is necessary to select a material having a thermal expansion coefficient close to prevent the flow path substrate 504 from warping. Therefore, it is preferable to use ceramic materials such as glass, silicon, SiO ₂ , ZrO ₂ , and Al ₂ O ₃ . The holding substrate 504 needs to have an opening for forming the common liquid chamber 506. The opening is connected to the ink supply port 507 of the flow path substrate 502. Further, a recess 522 of the holding substrate 504 is formed in a region facing the individual liquid chamber 509. It is necessary to secure a space in which the piezoelectric element can be driven and the diaphragm 501 can be displaced. As shown in FIG. 6, it is preferable that the concave portion 522 of the holding substrate 504 is partitioned for each individual liquid chamber 509 and bonded on the partition between the individual liquid chambers. Thereby, the rigidity of the thin channel substrate 502 can be increased, and mutual interference between adjacent liquid chambers when the piezoelectric element is driven can be reduced.

  Furthermore, as shown in FIG. 7, it is necessary to form a recess 523 of the holding substrate 504 in a region where the common electrode 511 is formed. It is necessary to select a film forming method capable of forming a thick film for the second common electrode wiring 518 described above. When a plating method, a screen printing method or the like is used, the film thickness uniformity tends to deteriorate. Therefore, if the portion where the common electrode wiring 518 is formed is used as a joint surface with the holding substrate 504, the ink sealability is deteriorated. In addition, if the adhesive is applied thick in order to absorb the film thickness variation, excess adhesive flows into the ink flow path and the piezoelectric element portion, and the characteristics are deteriorated. Therefore, it is necessary to form a recess 523 having a depth greater than or equal to the thickness of the second common electrode wiring 518 in the region of the holding substrate 504 facing the thick second common electrode wiring 518. The depth of the concave portion 523 of the holding substrate 504 is preferably a depth obtained by adding 10 to 30 [μm] to the film thickness of the second common electrode wiring 518.

  Further, the concave portion 522 of the holding substrate 504 and the concave portion 523 of the holding substrate 504 need to be provided separately. As shown in FIG. 5, the rigidity of the ink supply path 508 can be increased by the joint surface between the holding substrate 504 and the flow path substrate 502 formed between the recess 522 of the holding substrate 504 and the recess 523 of the holding substrate 504.

  Next, as shown in FIGS. 8 and 9, the modification of the present embodiment is different from the present embodiment in that the common electrode contact hole 520 is provided only on one side of the first common electrode wiring 514. is there. By doing in this way, the location of the contact hole used as the starting point of interface peeling can be reduced, and reliability can be ensured.

  Further, as shown in FIG. 10, another modification of the present embodiment is such that the second common electrode wiring 518 has a discontinuous shape, and the common electrode contact hole 520 is disposed between each common electrode wiring. By doing so, the second common electrode wirings 518 are separated from each other, whereby stress generated by plating or the like can be reduced, and interface peeling can be made difficult to occur.

Hereinafter, examples of the droplet discharge head of the present embodiment will be described.
(Example)
.phi.6 [inch], thickness 600 [[mu] m] of SiO ₂ 0.6 [μm] on a silicon wafer, 1.5 Si [[mu] m], 3 by laminating a SiO ₂ 0.4 [μm] After forming a diaphragm having a layered structure, a common electrode was formed by sputtering using Ti of 20 [nm] and Pt of 200 [nm]. A lead zirconate titanate (PZT) film having a thickness of 2 [μm] was formed on the common electrode by a sol-gel method using an organometallic solution, and then fired at 700 ° C. to form a PZT piezoelectric film. Thereafter, Pt was deposited on the piezoelectric film by a 200 [nm] sputtering method to form individual electrodes. After forming the individual electrodes, the individual electrodes, the piezoelectric body, and the common electrode were patterned by a dry etching method to form a piezoelectric element pattern having an arrangement as shown in FIG. The arrangement pitch of the piezoelectric elements was 85 [μm], and the width of the piezoelectric body was 50 [μm]. The length in the longitudinal direction of the piezoelectric element was set to 1000 [μm]. The number of piezoelectric elements arranged was 300.

  After the piezoelectric element is formed, an interlayer insulating film (insulating film 519 in FIG. 5) is formed by plasma CVD, and an individual electrode contact hole 524 and a common electrode contact hole 520 are formed in the interlayer insulating film 519 on the individual electrodes. Thereafter, Ti 50 nm and Al 500 nm are sequentially stacked and dry etched. As a result, the individual electrode wiring 513 and the first common electrode wiring 514 are patterned. Here, as shown in FIG. 4, the common electrode contact hole 520 is not disposed under the second common electrode wiring 518, but is disposed on both sides of the first common electrode wiring 514. Further, it is arranged not on the ink supply path but on the partition wall of the flow path substrate 502. This is because the contact hole is likely to be a starting point of interface peeling, and is therefore not disposed at a deformed location on the ink supply path. The electrode pattern was configured as shown in FIG. The width of the first common electrode wiring 514 was set to 300 [μm].

  After removing the diaphragm at the ink supply port portion shown in FIG. 4 by dry etching, a second common electrode wiring 518 made of Ni was formed on the first common electrode wiring 514 by electroless plating. The film thickness was 20 [μm] and the width was 200 [μm]. By forming the second common electrode wiring 518, the resistance can be greatly reduced. Further, since the common electrode contact hole 520 is not disposed under the common electrode wiring, even if a thick plating film as thick as 20 [μm] is formed, interfacial delamination between layers can be suppressed.

  A holding substrate 504 having recesses 522 and 523 of the holding substrate 504 and an opening of the holding substrate 504 was formed using a silicon wafer having a diameter of 6 inches. The concave portions 522 and 523 of the holding substrate 504 were formed by using an ICP dry etching method, and the depth was set to 30 [μm]. The opening of the holding substrate 504 was opened using a sand blast method. The holding substrate 504 was bonded by applying an epoxy adhesive to the bonding surface of the prepared holding substrate 504 with a film thickness of 2 [μm] using a flexographic printing machine and curing the adhesive. Thereafter, after the 600 [μm] flow path substrate 502 was polished to 80 [μm], the individual liquid chamber 509 and the ink supply path 508 were formed by the ICP dry etching method. The width of the individual liquid chamber 509 was 60 [μm], the width of the ink supply path 508 was 30 [μm], and the length was 300 [μm]. Etching of the ink supply path 508 and the individual liquid chamber 509 was performed until the vibration plate 501 was reached. Further, since the diaphragm 501 of the ink supply port 507 is etched in advance, a through-hole can be formed. After the wafer was cut into chips by dicing, the nozzle plate 503 and the flow path substrate 502 were bonded in the same manner as the holding substrate 504. As the nozzle plate 503, a SUS material having a thickness of 30 [μm] formed by press forming nozzles 510 having a diameter of 20 [μm] at a pitch of 85 [μm] was used. As shown in FIG. 4, a common liquid chamber substrate 505 made of SUS is bonded onto the holding substrate 504 and connected to an ink tank not shown in the drawing. Thus, an inkjet head could be obtained by bonding the TAB mounted with the driver IC to the individual electrode pad 517 by ACF bonding.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is first in a direction that is continuous in the nozzle arrangement direction and orthogonal to the nozzle arrangement direction. The contact hole is formed on both sides of the first common electrode wiring in which the second common electrode wiring is stacked. According to this, since the second common electrode wiring 518 is laminated on the first common electrode wiring 514 as described in the above embodiment, the common electrode is similar to the liquid droplet ejection head described in Patent Document 1. The resistance of the wiring can be reduced. Then, by performing the lamination process, the stress generated due to the difference in contraction rate between the first common electrode wiring 514 and the common electrode 512 due to the temperature change during the lamination process is intensively generated. A common electrode contact hole 520 provided in a portion of the first common electrode wiring 514 in which the electrode wiring 518 is stacked is formed on both sides of the first common electrode wiring in which the second common electrode wiring is stacked . For this reason, the stress is dispersed on the average inside the first common electrode wiring 514 in each common electrode contact hole 520. As a result, the stress dispersed on average in each of the common electrode contact holes 520 is common to the first common electrode wiring 514 formed by stacking the second common electrode wiring 518 as in Patent Document 1 described above. The stress is smaller than the stress generated intensively inside the first common electrode wiring 514 in the electrode contact hole 520. Therefore, peeling at the interface between the common electrode 512 and the first common electrode wiring 514 in each common electrode contact hole 520 can be suppressed. Thereby, it is possible to improve the uniformity of droplet discharge by satisfying both the reduction in the resistance of the common electrode wiring and the suppression of the occurrence of peeling at the interface between the common electrode and the common electrode wiring .
( Aspect B)
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is first in a direction that is continuous in the nozzle arrangement direction and orthogonal to the nozzle arrangement direction . is the formation in a substantially central portion of the common electrode lines, the contact hole, the second common electrode wires are formed only on one side of the first common electrode wires are stacked. According to this, as described in the modification of the above embodiment, the number of common electrode contact holes 520 that are the starting points of separation at the interface between the common electrode 512 and the first common electrode wiring 514 can be reduced. .
(Aspect C)
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is formed discontinuously in the nozzle arrangement direction. According to this, as described in another modification of the above-described embodiment, the common electrode wirings 518 are separated from each other, so that the action generated by plating or the like can be reduced. Then, peeling at the interface between the common electrode 512 and the first common electrode wiring 514 in the common electrode contact hole 520 can be made difficult to occur.
(Aspect D )
In any one of (Aspect A) to (Aspect C ), the contact hole is formed on a partition partitioning each individual liquid chamber. According to this, as described in another modification of the above embodiment, the internal pressure fluctuation due to the deformation displacement of the diaphragm occurs in the individual liquid chamber. When the common electrode contact hole 520 is provided above the individual liquid chamber, the deformation displacement of the diaphragm propagates to the common electrode contact hole 520, and the common electrode 512 and the first common electrode wiring 514 in the common electrode contact hole 520 Peeling easily occurs at the interface. For this reason, the common electrode contact hole 520 is formed on a partition partitioning each individual liquid chamber where the individual liquid chamber is not disposed. Accordingly, the propagation amount of the deformation displacement of the diaphragm can be reduced, and peeling at the interface between the common electrode 512 and the first common electrode wiring 514 in the common electrode contact hole 520 can be reduced.
(Aspect E )
(Aspect A) In any one of (Aspect C) , the first common electrode wiring is formed of any one of Al, Au, Ag, Pd, Ir, W, Ti, Ta, Cu, and Cr. According to this, as described in the above embodiment, the first common electrode wiring 514 has a low resistance and no voltage drop occurs in the common electrode 512 and the first common electrode wiring 514. Thereby, a sufficient driving voltage is stably applied to all the piezoelectric bodies of the recording head, and the uniformity of droplet ejection can be maintained.
(Aspect F )
In any one of (Aspect A) to (Aspect C ), the second common electrode wiring is formed of any one of Au, Ag, Cu, Ni, and Cr. According to this, as described in the above embodiment, the second common electrode wiring 518 has a low resistance, and the common electrode 512, the first common electrode wiring 514, and the second common electrode wiring 518 have a voltage drop. Don't be. Thereby, a sufficient driving voltage is stably applied to all the piezoelectric bodies of the recording head, and the uniformity of droplet ejection can be maintained.
(Aspect G )
An image is formed by discharging a recording liquid onto a recording material from a nozzle of any one of the droplet discharge heads of (Aspect A) to (Aspect F ). According to this, as described in the another embodiment, a sufficient driving voltage is stably applied to all the piezoelectric bodies of the recording head, and the uniformity of droplet ejection can be maintained. Therefore, highly reliable and stable droplet discharge can be performed, and a high-speed and high-quality image can be formed.

500 Recording head 501 Vibration plate 502 Channel substrate 503 Nozzle plate 504 Holding substrate 505 Common liquid chamber substrate 506 Common liquid chamber 507 Ink supply port 508 Ink supply channel 509 Individual liquid chamber 510 Nozzle 511 Individual electrode 512 Common electrode 513 Individual electrode wiring 514 First common electrode wiring 515 drive IC
516 Piezoelectric body 517 Individual electrode pad 518 Second common electrode wiring 519 Insulating film 520 Common electrode contact hole 521 Wiring 522 Recess 523 Recess 524 Individual electrode contact hole 525 Common electrode pad 526 Output terminal 527 Partition

JP 2006-255972 A

Claims (7)

A nozzle plate having a plurality of nozzles for discharging liquid, a liquid chamber substrate which is stacked on the nozzle plate and forms a plurality of individual liquid chambers respectively communicating with the nozzles, and a vibration constituting a part of the individual liquid chamber A plurality of piezoelectric bodies that pressurize each individual liquid chamber through a plate, a common electrode provided to sandwich the piezoelectric bodies and a piezoelectric actuator section having the individual electrodes, and the common electrode and the individual electrodes. A driving voltage applying means for applying a driving voltage therebetween, a first common electrode wiring for electrically connecting the common electrode and the driving voltage applying means, and a laminate on the first common electrode wiring. A first common electrode wiring including the first common electrode wiring in which the second common electrode wiring is stacked, and the first common electrode wiring is connected to the common electrode through a plurality of contact holes. And said When the driving voltage is applied between the common electrode and the individual electrode by the dynamic voltage applying means, the piezoelectric body is deformed and displaced, and the diaphragm is deformed and displaced, and the pressure in the individual liquid chamber is changed. In a droplet discharge head that discharges droplets from the nozzle by changing,
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is continuous with the nozzle arrangement direction and orthogonal to the nozzle arrangement direction. is formed at a substantially central portion in the direction of the first common electrode wiring, the contact hole, said second common electrode wirings are formed on both sides of the stacked first common electrode wirings A droplet discharge head that is characterized. A nozzle plate having a plurality of nozzles for discharging liquid, a liquid chamber substrate which is stacked on the nozzle plate and forms a plurality of individual liquid chambers respectively communicating with the nozzles, and a vibration constituting a part of the individual liquid chamber A plurality of piezoelectric bodies that pressurize each individual liquid chamber through a plate, a common electrode provided to sandwich the piezoelectric bodies and a piezoelectric actuator section having the individual electrodes, and the common electrode and the individual electrodes. A driving voltage applying means for applying a driving voltage therebetween, a first common electrode wiring for electrically connecting the common electrode and the driving voltage applying means, and a laminate on the first common electrode wiring. A first common electrode wiring including the first common electrode wiring in which the second common electrode wiring is stacked, and the first common electrode wiring is connected to the common electrode through a plurality of contact holes. And said When the driving voltage is applied between the common electrode and the individual electrode by the dynamic voltage applying means, the piezoelectric body is deformed and displaced, and the diaphragm is deformed and displaced, and the pressure in the individual liquid chamber is changed. In a droplet discharge head that discharges droplets from the nozzle by changing,
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is continuous with the nozzle arrangement direction and orthogonal to the nozzle arrangement direction. is formed at a substantially central portion in the direction of the first common electrode wiring, the contact hole, said second common electrode wires are formed only on one side of the laminated first common electrode wirings A droplet discharge head that is characterized. A nozzle plate having a plurality of nozzles for discharging liquid, a liquid chamber substrate which is stacked on the nozzle plate and forms a plurality of individual liquid chambers respectively communicating with the nozzles, and a vibration constituting a part of the individual liquid chamber A plurality of piezoelectric bodies that pressurize each individual liquid chamber through a plate, a common electrode provided to sandwich the piezoelectric bodies and a piezoelectric actuator section having the individual electrodes, and the common electrode and the individual electrodes. A driving voltage applying means for applying a driving voltage therebetween, a first common electrode wiring for electrically connecting the common electrode and the driving voltage applying means, and a laminate on the first common electrode wiring. A first common electrode wiring including the first common electrode wiring in which the second common electrode wiring is stacked, and the first common electrode wiring is connected to the common electrode through a plurality of contact holes. And said When the driving voltage is applied between the common electrode and the individual electrode by the dynamic voltage applying means, the piezoelectric body is deformed and displaced, and the diaphragm is deformed and displaced, and the pressure in the individual liquid chamber is changed. In a droplet discharge head that discharges droplets from the nozzle by changing,
The second common electrode wiring is stacked on a part of the first common electrode wiring, and the second common electrode wiring is formed discontinuously in the nozzle arrangement direction. Droplet discharge head. In the droplet discharge head according to any one of claims 1 to 3 ,
The droplet discharge head according to claim 1, wherein the contact hole is formed on a partition partitioning the individual liquid chambers. In the droplet discharge head according to any one of claims 1 to 3 ,
The liquid droplet ejection head, wherein the first common electrode wiring is formed of any one of Al, Au, Ag, Pd, Ir, W, Ti, Ta, Cu, and Cr. In the droplet discharge head according to any one of claims 1 to 3 ,
The liquid droplet ejection head, wherein the second common electrode wiring is formed of any one of Au, Ag, Cu, Ni, and Cr. Image forming apparatus and forming an image by ejecting the recording material the recording liquid from the nozzles of the droplet discharge head according to any one of claims 1-6.

Images