JP5862097B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

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

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. Devices such as ink jet recording devices are known.

  As a liquid discharge head, for example, a groove is formed on a piezoelectric body as pressure generating means for generating pressure by applying ink, which is liquid in a liquid chamber, in particular, a laminated piezoelectric member in which piezoelectric layers and internal electrodes are alternately stacked. A piezoelectric actuator having a plurality of columnar piezoelectric elements (piezoelectric columns) applied thereto, and deforming an elastically deformable diaphragm that forms a wall surface in the liquid chamber by displacement of the laminated piezoelectric member in the direction d33 or d31. A so-called piezoelectric head that discharges droplets by changing the volume and pressure in the room is known.

  As such a piezoelectric head, a piezoelectric member in which a plurality of piezoelectric element columns are formed, a common external electrode formed in the piezoelectric member and common to two or more piezoelectric element columns to which a drive signal is applied, and a common external It is known that a metal member disposed in parallel with a surface on which an electrode is formed, and the metal member and a common external electrode surface are directly electrically joined by a molten conductive material (Patent Document) 1).

  A piezoelectric member having a plurality of piezoelectric element columns in which piezoelectric layers and internal electrodes are alternately stacked; and a wiring member that feeds power to the piezoelectric element columns of the piezoelectric member. A first common external electrode provided on one of the opposing surfaces and an individual external electrode provided on the other surface, and connected to the first common external electrode on the surface side on which the individual external electrode is formed The wiring member is connected to the surface of the piezoelectric member on which the individual external electrodes are formed, and feeds power to the individual external electrode and the second common external electrode to connect to the piezoelectric member. A common electrode wiring connected across a plurality of second common external electrodes formed on the plurality of piezoelectric element columns, and a receding from the front end direction with respect to the common electrode wiring. And individual electrode wiring connected to It is known to (Patent Document 2).

JP 2011-086896 A JP 2011-056730 A

  However, in the configuration disclosed in Patent Document 1, it is necessary to add a metal member, which increases the cost. Further, since the heat capacity of the metal member is large, it is necessary to increase the thermal energy when joining the common electrode of the piezoelectric member and the metal member, which may result in poor bonding or depolarization of the piezoelectric member.

  In the configuration disclosed in Patent Document 2, since the common wiring of the wiring member is provided on the driving surface side of the piezoelectric member from the individual electrode portion, the wiring member mounted with the driving IC or the like is more piezoelectric than the individual electrode. An electrode for IC operation inspection is provided on the drive surface side of the member, and after the inspection, the electrode is cut between the individual electrode and the operation inspection electrode, and the bonding electrode portion with the piezoelectric element is used as the terminal portion of the wiring board. Needs to be multilayer wiring. Further, in order to use the individual electrode as the operation inspection electrode, the inspection cost becomes high, for example, by using an inspection probe that can be soft-touched so as not to damage the individual electrode.

  This invention is made | formed in view of said point, and it aims at reducing the joining defect of a piezoelectric member and a wiring member, and the damage of both members, without causing the increase in member cost or test | inspection cost.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A plurality of piezoelectric columns arranged corresponding to a plurality of individual liquid chambers through which nozzles for discharging liquid droplets communicate, and at least one common electrode extracting piezoelectric column not corresponding to the individual liquid chambers extend along the nozzle arrangement direction. Two piezoelectric members provided
A flexible wiring member that gives a drive signal to a plurality of piezoelectric pillars of the two piezoelectric members;
The two piezoelectric members are arranged at a predetermined interval in a direction orthogonal to the nozzle arrangement direction,
Wherein the two piezoelectric members, respectively, on the inner surface facing in a direction orthogonal to the nozzle arrangement direction, the plurality of common first common external electrode to a piezoelectric column provided, the outer surface side opposite to the inner surface side In addition, an individual external electrode for each of the plurality of piezoelectric columns is provided, and a second common external electrode that communicates with the first common external electrode on the inner surface side is provided on the piezoelectric column for taking out the common electrode,
The wiring member is provided with an opening corresponding to the two piezoelectric members, and is bent on the outer surface side of the two piezoelectric members across the two piezoelectric members,
The wiring member is provided with an individual electrode wiring and a first common electrode wiring, and is connected to an individual external electrode and a second common external electrode on the outer surface side of the two piezoelectric members,
The wiring member is provided with a second common electrode wiring that communicates with the first common electrode wiring along a nozzle arrangement direction between the two piezoelectric members, and the second common electrode wiring is connected to the two piezoelectric members. It was set as the structure connected to the said 1st common external electrode of the said inner surface side.

According to the onset bright, without causing an increase in material cost and inspection cost can be reduced damage bonding failure or both members of the piezoelectric member and the wiring member.

It is an exploded perspective view showing an example of a liquid discharge head concerning the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is sectional explanatory drawing of the bipitch structure along the liquid chamber transversal direction of the head. It is sectional explanatory drawing of the normal pitch structure along the liquid chamber transversal direction of the head. It is plane explanatory drawing of the state before bending FPC with which it uses for description of 1st Embodiment of this invention. It is a side explanatory view similarly. FIG. 6 is a cross-sectional explanatory view taken along line AA in FIG. 5 in a state after the FPC is bent and joined. FIG. 6 is a cross-sectional explanatory view taken along the line BB in FIG. 5. It is sectional explanatory drawing of the direction orthogonal to the nozzle arrangement direction explaining the connection structure of a piezoelectric member and FPC. It is side explanatory drawing similar to FIG. 6 with which it uses for description of 2nd Embodiment of this invention. FIG. 4 is a side explanatory view of a mechanism portion for explaining an example of an image forming apparatus according to the present invention. It is a principal part top explanatory drawing of a mechanism part similarly.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional explanatory view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIGS. 3 and 4 are nozzle arrangement directions of the head. It is sectional explanatory drawing of the different example along (liquid chamber transversal direction).

  The liquid discharge head includes a flow path substrate (liquid chamber substrate) 1 formed of a SUS substrate, a vibration plate member 2 bonded to the lower surface of the flow path substrate 1, and a nozzle plate 3 bonded to the upper surface of the flow path substrate 1. And a plurality of individual liquid chambers (pressurized liquid chambers, pressure chambers) as individual flow paths through which the plurality of nozzles 4 that discharge droplets (liquid droplets) communicate with each other via the nozzle communication path 5. , Also referred to as a pressurizing chamber, a flow path, etc. Hereinafter, also referred to simply as a “liquid chamber”.) 6, a fluid resistance portion 7 that also serves as a supply path for supplying ink to the liquid chamber 6, and the fluid resistance portion 7 A communication portion 8 communicating with the liquid chamber 6 is formed, and ink is supplied from a common liquid chamber 10 formed in a frame member 17 described later through a supply port 9 formed in the diaphragm member 2 in the communication portion 8.

  The flow path substrate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path substrate 1 is formed by etching the SUS substrate using an acidic etchant or machining such as punching (pressing) to open openings such as the communication path 5, the pressurized liquid chamber 6, and the fluid resistance portion 7. Each is formed.

  The diaphragm member 2 has each vibration region (diaphragm portion) 2a that forms a wall surface corresponding to each liquid chamber 6, and an island-shaped convex portion on the outer side of the vibration region 2a (on the side opposite to the liquid chamber 6). 2b is provided, and the upper end surfaces (joint surfaces) of the piezoelectric columns 12A and 12B of the laminated piezoelectric member 12 as drive means (actuator means, pressure generating means) for deforming the vibration region 2a are joined to the island-shaped convex portions 2b. doing. The lower end surface of the multilayer piezoelectric member 12 is joined to the base member 13.

  Here, the piezoelectric member 12 is formed by alternately laminating piezoelectric material layers 21 and internal electrodes 22a and 22b. The internal electrodes 22a and 22b are respectively substantially perpendicular to the end face, that is, the diaphragm member 2 of the piezoelectric member 12. By pulling out to the side surface, connecting to the end face electrodes (external electrodes) 23, 24 formed on the side face, and applying a voltage between the end face electrodes (external electrodes) 23, 24, displacement in the stacking direction occurs. Here, the external electrode 23 is used as an individual external electrode (individual electrode), and the external electrode 24 is used as a first common external electrode (common electrode).

  This piezoelectric member 12 forms grooves 40 by half-cut dicing, thereby forming piezoelectric pillars 12A and 12B, which are a required number of pillar-shaped piezoelectric elements, for one piezoelectric member 12 in a comb-like shape at a predetermined interval. It is a thing.

  The piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, but a piezoelectric column that is driven by giving a driving waveform is a driving column 12A, and a piezoelectric column that is used as a simple column without giving a driving waveform is a non-driving column. It is distinguished as 12B. In this case, as shown in FIG. 3, a bi-pitch configuration in which drive columns 12A and non-drive columns 12B are used alternately, or a normal pitch configuration in which all piezoelectric columns are used as drive columns 12A as shown in FIG. Either can be adopted.

  The piezoelectric member 12 is connected to an FPC 15 as a flexible wiring member for giving a driving signal to the driving column 12A.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the liquid chambers 6 and bonded to the flow path substrate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  Further, a frame member 17 formed by injection molding with an epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the actuator portion constituted by the piezoelectric member 12, the base member 13, the FPC 15, and the like. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port 19 for supplying a recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as an ink cartridge.

  In the liquid ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the drive column 12A according to an image recorded from a control unit (not shown). As a result, the driving column 12A to which the pulse voltage is applied is displaced to deform the vibration region 2a of the vibration plate member 2 in the direction of the nozzle plate 3, and the liquid in the liquid chamber 6 is changed by the volume (volume) change of the liquid chamber 6. By applying pressure, droplets are discharged from the nozzles 4 of the nozzle plate 3.

  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, when the voltage application to the drive column 12A is turned off, the diaphragm member 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. . At this time, ink is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  In addition to the above-described punching, the liquid discharge head is not limited to the pulling method (a method in which the vibrating plate member 2 is released from the pulled state and pressurized with a restoring force), and the pulling-pushing method (the vibrating plate member 2 is fixed). It can also be driven by a method such as a method of holding at an intermediate position, pulling from this position, and then extruding.

  Next, a first embodiment of the present invention will be described with reference to FIGS. 5 is an explanatory plan view of a state before the FPC is bent for explanation of the embodiment, FIG. 6 is a side explanatory view, and FIG. 7 is an AA line of FIG. 5 in a state after the FPC is bent and joined. 8 is a cross-sectional explanatory view taken along the line BB in FIG. 5, and FIG. 9 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction for explaining the connection structure between the piezoelectric member and the FPC.

  At one end (or both ends) of one piezoelectric member 12, a common electrode extraction piezoelectric column 12Ba which is a non-driving column having a width (hereinafter the same) in the piezoelectric column arrangement direction (nozzle arrangement direction) wider than the driving column 12A. The other piezoelectric pillars have a bi-pitch configuration in which the driving pillars 12A and the non-driving pillars (posts) 12B are alternately used.

  As shown in FIG. 8, the two piezoelectric members 12 and 12 are arranged on the base member 13 at a predetermined interval in a direction orthogonal to the nozzle arrangement direction. In this case, the piezoelectric members 12 and 12 are configured so that the drive columns 12A are arranged in a staggered manner.

  Here, as described above, the two piezoelectric members 12 and 12 have a common external electrode (this is referred to as a “first common electrode”) common to the plurality of drive pillars 12A on the inner surface facing in the direction orthogonal to the nozzle arrangement direction. 24) and an individual external electrode 23 for each of the plurality of driving columns 12A is provided on the outer surface side opposite to the inner surface side.

  In addition, the piezoelectric column 12Ba for taking out the common electrode of the piezoelectric members 12 and 12 has a second outer side that leads to the first common external electrode 24 on the inner side on the same outer side as the surface on which the individual external electrode 23 of the driving column 12A is provided. A common external electrode 25 is provided.

  The individual external electrode 23, the first common external electrode 24, and the second common external electrode 25 are formed by forming a metal film with a thickness of about 1 μm by sputtering or the like. The metal film is a multilayer film of Cr, Ni, Cu, Au or the like, and the outermost surface is an Au film having high bonding reliability with solder.

  Further, the height H2 of the common electrode take-out piezoelectric column 12Ba is lower than the height H1 of the other piezoelectric columns 12A and 12B (H2 <H1). This height difference (H1-H2) is the thickness of the electrode portion (base material 31 + wiring 32 + connecting member (solder) 41) of the FPC 15−the height of the island-like convex portion 2b of the diaphragm member 2.

  In addition, the height of the inactive region portion where the voltage is not applied without being sandwiched between the internal electrodes 22a and 22b on the first common external electrode 24 side of the piezoelectric member 12 is the common electrode extraction provided with the second common external electrode 25. The height is the same as the height H2 of the piezoelectric pillar 12Ba for use.

  Here, since the base material 31 of the FPC 15 has a height that does not exceed the piezoelectric column 12A, the piezoelectric columns excluding the piezoelectric columns 12Ba at both ends regardless of the height of the island-shaped convex portions 2b of the diaphragm member 2. 12A, 12B and the diaphragm member 2 can be joined.

  In addition, the common electrode take-out piezoelectric column 12Ba of the piezoelectric member 12 and the inactive region portion on the first common external electrode 24 side having the same height are set to a height at which the uppermost internal electrode 22b is partially exposed. . In addition, as a method of forming the height of the piezoelectric member 12 partially low, a method of removing by mechanical processing can be used.

  On the other hand, the FPC 15 includes a base material 31, an individual electrode wiring 32A, a first common electrode wiring 32B, a second common electrode wiring 32C (referred to as “wiring 32” when not distinguished), a solder resist 33, and a drive IC 34 mounted thereon. Has been.

  The wiring 32 is made of highly conductive Cu, for example, with a film thickness of 8 μm. In the case of lower resistance, those having a film thickness of 12, 18, 35 μm or the like can be used.

  The solder resist 33 is formed in a region 15 </ b> B that faces the side surface of the base member 13 of the FPC 15.

  The electrode portion 15A of the FPC 15 is used as an electrode wiring because the wiring 32 is exposed.

  Further, the FPC 15 is formed with an opening 15 </ b> C corresponding to the two piezoelectric members 12, 12 by punching the base material 31.

  Here, the individual electrode wiring 32 </ b> A is disposed inside the first common electrode wiring 32 </ b> B and is formed up to the connection terminal of the drive IC 34.

  The first common electrode wiring 32 </ b> B is disposed outside the individual electrode wiring 32 </ b> A, is pulled out to a position corresponding to the space between the two piezoelectric members 12, 12, and is arranged in a nozzle array at a position corresponding to the space between the two piezoelectric members 12, 12. It is connected to the second common electrode wiring 32C provided along the direction.

  Here, two drive ICs 34 and 34 for driving the two piezoelectric members 12 are mounted on the FPC 15. Further, the FPC 15 connects the first common electrode wirings 32 </ b> B connected to the two piezoelectric members 12, 12 to make the potentials of the first common external electrodes 24 of the two piezoelectric members 12, 12 the same. In addition, when it is not necessary to make the electric potential of the common external electrode 24 of the two piezoelectric members 12 and 12 the same, it is not necessary to connect the first common electrode wirings 32B.

  In addition, solder 41 is formed on the wiring 32 in advance by a printing method, a plating method, or the like.

  The two piezoelectric members 12 and 12 and the FPC 15 include the individual external electrode 23 and the individual electrode wiring 32A, the second common external electrode 25 and the first common electrode wiring 32B, and the first common external electrode 24 and the second common electrode wiring 32C. The internal electrode 22b and the second common electrode wiring 32C are joined by solder 41 and are electrically connected.

Next, the joining process of the piezoelectric member 12 and the FPC 15 will be described.
First, the FPC 15 is aligned with the two piezoelectric members 12 and 12, and the joint surfaces of the piezoelectric columns 12A and 12B with the diaphragm member 2 excluding the piezoelectric columns 12Ba at both ends of the piezoelectric member 12 are exposed from the opening 15C. In this state, the two piezoelectric members 12 and 12 are overlapped.

  Next, the FPC 15 is bent at a portion 15D corresponding to a corner on the outer surface side of each of the piezoelectric members 12 and 12, and the individual electrode wiring 32A, the first common electrode wiring 32B, the individual external electrode 23 of the piezoelectric members 12 and 12, Two common external electrodes 25 are stacked. Then, the individual electrode wiring 32A and the first common electrode wiring 32B of the FPC 15 are joined to the individual external electrode 23 and the second common external electrode 25 of the piezoelectric members 12 and 12 by pressurizing and heating the joint portion.

  Further, the second common electrode wiring 32C of the FPC 15 and the first common external electrode 24 and the internal electrode 22b of the piezoelectric members 12 and 12 are joined in the same manner.

  Specifically, a heater joining method for joining by heating the base material 31 on the back surface of the electrode portion 15A of the FPC 15 with a heater chip (block) while increasing the temperature of the heater chip in a pulsed manner to melt and cure the solder 41. In addition, a laser bonding method or the like can be used in which the FPC 15 is pressed by a laser transmitting rigid member such as glass and the solder is melted and cured by irradiating the wiring 32 and the solder 41 with laser light.

  In particular, the bonding between the second common electrode wiring 32C and the first common external electrode 24 and the internal electrode 22b of the piezoelectric member 12 is preferably performed by a laser bonding method because the space between the two piezoelectric members 12 and 12 is narrow.

  The solder 41 may be any material that has a lower melting point than the wiring 32 and the base material 31 of the FPC 15 made of a metal member and is made of a conductive material. Lead (Pb) It is preferable that it does not contain. For example, as the solder 41, solder containing tin (Sn) and bismuth (Bi) as main components can be used. Since lead is not contained, it is effective from the viewpoint of environmental protection, and the solder 41 mainly composed of tin (Sn) and bismuth (Bi) has a very low melting point among non-lead members. Therefore, the electrodes of the FPC 15 and the electrodes of the piezoelectric member 12 can be easily welded without damaging the FPC 15 and the piezoelectric member 12.

  Here, the solder 41 is used as the electrical connection member, but an anisotropic conductive film, a conductive adhesive, or the like can also be used.

  This electrical connection member can be formed on the external electrode of the piezoelectric member 12, but by forming it on the wiring 32 (electrode portion 15 </ b> A) of the FPC 15, the exposed portion of the internal electrode 22 b of the piezoelectric member 12 and the second portion of the FPC 15. The common electrode wiring 32C can also be bonded.

  Here, FPC is used as the wiring member. However, it may be any film that is thin and is provided with a plurality of electrodes arranged in parallel with each other and can be bent. For example, TAB (Tape Automated Bonding) may be used. it can.

  Further, the second common electrode wiring 32C of the FPC 15 connected to the two piezoelectric members 12 is separately formed. Thereby, the heat dissipation with respect to the heating amount can be reduced during bonding, and the temperature rise of the bonded portion can be suppressed. That is, thermal damage to the piezoelectric member 12 and the FPC 15 during bonding can be reduced.

  When there is little thermal damage to the piezoelectric element and FPC during bonding, the second common electrode wiring 32C connected to the two piezoelectric members 12 may be made as one thick wiring without being separated. Further, the first common external electrode 24 of the piezoelectric member 12, the exposed internal electrode 22b, and the second common electrode wiring 32C of the FPC 15 may be joined in a spot shape without being joined together.

  As described above, one wiring member having flexibility is bent, and the wiring of the wiring member and the inner and outer electrodes of the two piezoelectric members are connected by the electric connection member. Since most of the current flowing in the current flows in the second common electrode wiring of the wiring member, more current can flow than in the case where only the second common external electrode having a high wiring resistance is energized.

  In other words, as the head is lengthened and densified, it is possible to prevent burning or scorching due to heat generation even when the current to the common electrode increases, especially when simultaneously driving multiple channels of piezoelectric columns. In addition, since the resistance is increased, the discharge characteristics of the central channel are not deteriorated as compared with the channel at the end of the piezoelectric member, and stable droplet discharge can be realized stably.

  Also, compared to the case where a metal member is added between two piezoelectric members, the cost of the member is not increased, and the heat capacity of the second common electrode wiring of the wiring member is sufficiently small compared to the heat capacity of the metal member, so that the bonding failure And depolarization of the piezoelectric element can be suppressed.

  Further, by providing an IC inspection pad in the opening 15C of the FPC 15, there is no cost increase related to the inspection of the FPC which is a wiring member.

  In addition, the height of at least a part of the common electrode extraction piezoelectric column 12Ba provided with the second common external electrode 25 at the ends of the two piezoelectric members 12 and 12 is set lower than the other piezoelectric columns 12A and 12B. . Accordingly, the second common electrode wiring 32C and the piezoelectric member are connected in a state where the first common electrode wiring 32B of the FPC 15 is connected to the second common electrode wiring 32C in which the driving electrode is connected between the two piezoelectric members 12 and 12. It is possible to achieve both the connection of the 12 first common external electrodes 24 and the bonding of the piezoelectric member 12 and the diaphragm member 2.

  In addition, the height of the inactive region where no voltage is applied to the inner surface of the piezoelectric columns of the two piezoelectric members 12 and 12 is made the same as the height of the piezoelectric column for taking out the common electrode provided with the second common external electrode. Therefore, the interval between the two piezoelectric members can be narrowed.

  In addition, since the uppermost internal electrode is exposed in the portion where the height of the common electrode extraction piezoelectric column provided with the second common external electrode is lowered and the inactive region portion, the exposed internal electrode and the FPC Wiring can be connected by an electrical connection member, and the resistance of the common electrode wiring portion can be further reduced.

  Furthermore, since the second common electrode wiring 32C and the first common external electrode 24 of the piezoelectric member 12 are vertically joined, the connection area is small, but by connecting the second common electrode wiring 32C and the exposed internal electrode 22b, The connection area is increased and the connection reliability is improved.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 is an explanatory side view similar to FIG. 6 for explaining the embodiment.

  In the first embodiment, the entire height of the common electrode lead-out piezoelectric column 12Ba provided with the second common external electrode 25 is lowered, whereas in the present embodiment, the common common electrode provided with the second common external electrode 25 is provided. The height of the electrode extraction piezoelectric column 12Ba is partially lower than the other piezoelectric columns 12A and 12B.

  Even if comprised in this way, the effect similar to the said 1st Embodiment can be acquired.

  Next, an example of an image forming apparatus equipped with the liquid ejection head according to the present invention will be described with reference to FIGS. FIG. 11 is an explanatory side view of the mechanism of the apparatus, and FIG. 12 is an explanatory plan view of the main part of the mechanism.

  This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 has recording heads 234a and 234b (which are composed of liquid ejection heads according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). When not distinguished, it is referred to as “recording head 234”). A nozzle row composed of a plurality of nozzles is arranged in the sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ink droplet ejection direction facing downward.

  Each of the recording heads 234 has two nozzle rows. One nozzle row of the recording head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 234b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. In this example, four-color droplets are ejected in a two-head configuration. However, a recording head for each color can be provided, and a nozzle row in which a plurality of nozzles ejecting four-color droplets are arranged. It is also possible to have a single recording head configuration.

  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 via a supply tube 236 for each color by a supply unit (not shown).

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  In addition, in the non-printing area on the other side in the scanning direction of the carriage 233, the liquid that receives liquid droplets when performing idle ejection that ejects liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ink recovery unit (empty discharge receiver) 288 that is a recovery container is disposed, and the ink recovery unit 288 includes an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the image forming apparatus includes the liquid ejection head according to the present invention, there is no bonding failure, the reliability of the recording head is improved, and stable recording can be performed.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Nozzle plate 3 Vibration plate 4 Nozzle 6 Individual liquid chamber 10 Common liquid chamber 12 Piezoelectric member 12A Piezoelectric column (drive column)
12B Piezoelectric column (non-driven column)
12Ba Piezoelectric column for common electrode extraction 13 Base member 15 FPC (wiring member)
15C opening 23 individual external electrode 24 first common external electrode 25 second common external electrode 31A individual electrode wiring 31B first common electrode wiring 31C second common electrode wiring 234 carriage 235 recording head

Claims (5)

A plurality of piezoelectric columns arranged corresponding to a plurality of individual liquid chambers through which nozzles for discharging liquid droplets communicate, and at least one common electrode extracting piezoelectric column not corresponding to the individual liquid chambers extend along the nozzle arrangement direction. Two piezoelectric members provided
A flexible wiring member that gives a drive signal to a plurality of piezoelectric pillars of the two piezoelectric members;
The two piezoelectric members are arranged at a predetermined interval in a direction orthogonal to the nozzle arrangement direction,
Wherein the two piezoelectric members, respectively, on the inner surface facing in a direction orthogonal to the nozzle arrangement direction, the plurality of common first common external electrode to a piezoelectric column provided, the outer surface side opposite to the inner surface side In addition, an individual external electrode for each of the plurality of piezoelectric columns is provided, and a second common external electrode that communicates with the first common external electrode on the inner surface side is provided on the piezoelectric column for taking out the common electrode,
The wiring member is provided with an opening corresponding to the two piezoelectric members, and is bent on the outer surface side of the two piezoelectric members across the two piezoelectric members,
The wiring member is provided with an individual electrode wiring and a first common electrode wiring, and is connected to an individual external electrode and a second common external electrode on the outer surface side of the two piezoelectric members,
The wiring member is provided with a second common electrode wiring that communicates with the first common electrode wiring along a nozzle arrangement direction between the two piezoelectric members, and the second common electrode wiring is connected to the two piezoelectric members. The liquid discharge head is connected to the first common external electrode on the inner surface side.   The liquid discharge head according to claim 1, wherein the height of at least a part of the common electrode take-out piezoelectric column is lower than the other piezoelectric columns.   3. The liquid ejection head according to claim 1, wherein a height of the inactive region portion on the inner surface side of the two piezoelectric members is the same as a height of the piezoelectric column for taking out the common electrode.   The liquid ejection head according to claim 2, wherein the common electrode extraction piezoelectric column has an internal electrode exposed at a portion whose height is lower than that of the other piezoelectric column.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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