JP2013014030A - Liquid ejection head and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that a wiring member or a piezoelectric member is enlarged, and part cost is increased.SOLUTION: A piezoelectric column 12B for removing a common electrode, which is wider than a drive column 12A, is formed at one end of a piezoelectric member 12. A common external electrode 25 for taking out connected with the common electrodes 24 of all the drive columns 12A is provided on the end face of the piezoelectric columns 12B at the individual electrode side. Individual wiring electrodes 31A of an FPC 15 are electrically connected to the individual external electrodes 23 of each of the drive columns 12A, and individual wiring electrodes 31B of the FPC 15 are electrically connected to the removal common external electrodes 25 of the piezoelectric columns 12B. A height Hb of the piezoelectric columns 12B is about as half as that of the drive columns 12A. An area per unit length in a piezoelectric column arrangement direction of the removal common external electrodes 25 is equal to the area per unit length in a piezoelectric column arrangement direction of the individual external electrodes 23.

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.

  In such a piezoelectric head, a common external electrode (also referred to as an end face electrode) serving as a common electrode in which an internal electrode of a piezoelectric column is drawn out to an end face and an individual external electrode serving as an individual electrode are respectively FPC (flexible substrate, flexible printed cable). Common wiring electrodes and individual wiring electrodes of a wiring member such as a flexible wiring board are joined, and a drive signal corresponding to an image signal is given to each piezoelectric column.

  In this case, as a method of electrically connecting a wiring electrode provided on a wiring member such as an FPC and an external electrode of a piezoelectric column, for example, a metal is interposed between both electrodes, and both electrodes are made of a laser such as glass. A method in which both electrodes are welded and joined together by melting the metal with a laser beam by bonding with a transmission rigid member, and both electrodes are made of metal by melting the metal by thermocompression bonding such as a heater. A method of welding and joining is known.

  By the way, since the amount of current flowing through the common electrode of the piezoelectric head is much larger than the amount of electricity flowing through the individual electrodes, conventionally, one end or both ends in the direction of arranging the piezoelectric columns is used as a common external electrode of a plurality of piezoelectric columns. A common electrode extraction piezoelectric column having a common external electrode for extraction (also referred to as a common electrode portion) is provided, and the width of the common electrode extraction piezoelectric column is made wider than the width of the individual piezoelectric column corresponding to each nozzle. Moreover, the width of the common wiring electrode connected to the common external electrode for taking out wiring members such as FPC is made wider than the width of the individual wiring electrode connected to the individual external electrode (Patent Document 1).

  However, when the common electrode portion (the connection portion between the common external electrode for extraction and the common wiring electrode) becomes wide, the amount of electrical connection members (solder, etc.) to be used becomes smaller between the individual electrode portions (the individual external electrodes and the individual wiring electrodes). It is necessary to give a large amount of heat at the time of connection. Similarly, since the common electrode portion is wider than the individual electrode portion in terms of the width of the wiring electrode and the width of the piezoelectric column, the amount of heat flowing to the wiring electrode and the like when connecting the common electrode portion increases, and it is necessary to give a large amount of heat also in this respect.

  Therefore, at least the solder joint portion of the FPC common wiring electrode connected to the common external electrode for extraction on the piezoelectric column side is formed in a plurality of fine line patterns, and the solder thickness of the joint portion of the common wiring electrode is set to the joint portion of the individual wiring electrode. (PTL 2), dividing the common external electrode for taking out into two and making each connection width equal to the width of the individual external electrode (PTL 3), common wiring of wiring members It is known that the electrodes are comb-shaped, the common wiring electrode length is shortened (Patent Document 4), and the wiring width (cross-sectional area) in the vicinity of the connecting portion of the wiring member is decreased (Patent Document 5). Yes.

  However, as described above, by making the electrode width of the common wiring electrode of the FPC the same as the electrode width of the individual wiring electrode, it is possible to achieve a certain improvement with respect to the bonding to the wide common external electrode for extraction on the piezoelectric column side. Since the heat capacity of the common external electrode for extraction on the piezoelectric column side is large, there arises a problem that the bonding strength of the solder is lowered.

  This reduction in bonding strength becomes a greater problem as the liquid ejection head becomes larger and denser. That is, if the head is small and has a low density, it can be joined by heating with a heater chip, and since the entire joining surface is heated, the difference in heat capacity does not matter so much, but the head becomes long (large ), When the density is increased, joining with the heater chip becomes difficult. Therefore, laser bonding is performed as described above. This is a method in which electrodes are bonded one by one by scanning a laser, and there is an advantage that the flexible substrate can be restrained from being stretched and the flexible substrate can be easily bonded to a large head.

  However, since the heating time per electrode is short in laser bonding, in the configuration of the wide extraction common external electrode described above, all the heat from the laser is absorbed by the wide extraction common external electrode of the piezoelectric column, It has been found that there is a problem that the solder cannot be joined without melting.

  In this case, it is conceivable to extend the laser irradiation time only when bonding with the common electrode part, but this cannot increase the tact time and suppress the expansion of the flexible substrate, which is the greatest feature of laser bonding. Such problems occur.

  Therefore, the width of the common external electrode for taking out the piezoelectric pillar is made equal to the width of the individual wiring electrode (Patent Document 6), or the common wiring electrode of the wiring member is divided into a plurality of parts and the width of the common wiring electrode is set to the individual wiring electrode. (Patent Document 7) makes it possible to bond a wiring member to a piezoelectric element of a long and high-density head without sacrificing the increase in tact time and the advantage of laser bonding. It has been done.

JP 2006-175845 A JP-A-11-34309 Japanese Patent Laid-Open No. 10-202876 JP 2002-86739 A JP 2006-210855 A JP 2009-160855 A JP 2010-214791 A

  However, as disclosed in Patent Document 7, when the common wiring electrode of the wiring member is divided into a plurality of parts and the width of the common wiring electrode is narrower than the width of the individual wiring electrode, the current for driving the piezoelectric column is reduced. In order to make it the same as before, it is necessary to increase the common wiring electrode area of the wiring member and the common external electrode width of the piezoelectric column. As a result, the wiring member and the piezoelectric column become large, and it is difficult to reduce the size. There is a problem that the cost becomes high.

  The present invention has been made in view of the above problems, and without increasing the size of the wiring member and the piezoelectric member and increasing the member cost, prevents an increase in tact time when the wiring member is joined to the piezoelectric column, The purpose is to enable joining in a short time.

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 droplets communicate;
At least one common electrode take-out piezoelectric column that does not correspond to the individual liquid chamber and has a wider width in the piezoelectric column arrangement direction than the plurality of piezoelectric columns;
A wiring member for providing a drive signal to the plurality of piezoelectric pillars,
The plurality of piezoelectric pillars are provided with individual external electrodes and common external electrodes,
The common electrode extraction piezoelectric column is provided with a common external electrode for extraction that leads to a common external electrode of the plurality of piezoelectric columns,
The individual external electrode is connected to an individual wiring electrode provided on the wiring member by an electrical connection member,
A common wiring electrode provided on the wiring member by an electrical connection member is connected to the common external electrode for extraction,
The area per unit length in the piezoelectric column arrangement direction of the extraction common external electrode is equal to or smaller than the area per unit length in the piezoelectric column arrangement direction of the individual external electrode.

The 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 droplets communicate;
At least one common electrode take-out piezoelectric column that does not correspond to the individual liquid chamber and has a wider width in the piezoelectric column arrangement direction than the plurality of piezoelectric columns;
A wiring member for providing a drive signal to the plurality of piezoelectric pillars,
The plurality of piezoelectric pillars are provided with individual external electrodes and common external electrodes,
The common electrode extraction piezoelectric column is provided with a common external electrode for extraction that leads to a common external electrode of the plurality of piezoelectric columns,
The individual external electrode is connected to an individual wiring electrode provided on the wiring member by an electrical connection member,
A common wiring electrode provided on the wiring member by an electrical connection member is connected to the common external electrode for extraction,
The average height of the common external electrode for extraction is set to be (the height of the individual external electrode × the individual external electrode width / the individual electrode pitch) or less.

  Here, the connection end of each wiring electrode of the wiring member may be positioned between the leading end position of the common external electrode for extraction and the leading end position of the individual external electrode.

Further, the joint end of the individual wiring electrode of the wiring member is located between the tip position of the common external electrode for extraction and the tip position of the individual external electrode,
Of the joint ends of the common wiring electrodes of the wiring member, at least the corner portion located outside in the piezoelectric column arrangement direction can be configured to be positioned closer to the base side of the column than the tip position of the extraction common external electrode.

  Further, the height of a part of the common electrode extraction piezoelectric column may be the same as the height of the plurality of piezoelectric columns.

  In addition, a piezoelectric column having the same height as the plurality of piezoelectric columns may be provided on the outer side in the piezoelectric column arrangement direction than the piezoelectric column for taking out the common electrode.

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

  According to the liquid ejection head of the present invention, the area per unit length in the piezoelectric column arrangement direction of the common external electrode for extraction is equal to or less than the area per unit length in the piezoelectric column arrangement direction of the individual external electrode. Without increasing the size of the wiring member and the piezoelectric member and increasing the member cost, it is possible to prevent an increase in tact time when the wiring member is joined to the piezoelectric column and to join in a short time.

  According to the liquid ejection head according to the present invention, since the average height of the common external electrode for extraction is equal to or less than (the height of the individual external electrode × the width of the individual external electrode / the individual electrode pitch), Without increasing the size of the piezoelectric member and increasing the member cost, it is possible to prevent an increase in tact time when the wiring member is bonded to the piezoelectric column, and to perform the bonding in a short time.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, stable image formation can be performed.

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 typical sectional explanatory drawing which follows the direction orthogonal to the nozzle arrangement direction with which it uses for description of 1st Embodiment of this invention. It is a principal part plane explanatory drawing of the joined state in the direction along a nozzle arrangement direction similarly. It is a principal part front explanatory drawing of a piezoelectric member and FPC similarly. It is a principal part front explanatory drawing in a joined state similarly. It is a principal member front explanatory drawing of a piezoelectric member and FPC used for explanation of a comparative example. It is a principal part front explanatory drawing in a joined state similarly. It is principal part front explanatory drawing of the joining state of the piezoelectric member and wiring member in 2nd Embodiment of this invention. It is principal part front explanatory drawing of the joining state of the piezoelectric member and wiring member in 3rd Embodiment of this invention. It is principal part front explanatory drawing of the joining state of the piezoelectric member and wiring member in 4th Embodiment of this invention. It is a side explanatory view of a mechanism part for explaining an example of an image forming apparatus equipped with a liquid discharge head 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 obtained by alternately stacking the piezoelectric material layers 21 and the internal electrodes 22a and 22b, and the internal electrodes 22a and 22b are respectively substantially perpendicular to the end face, that is, the diaphragm member 2 of the piezoelectric element 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 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 FPC 15 is bonded to the base member 13 with a hot melt adhesive 16 in the vicinity of the piezoelectric member 12.

  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 respective liquid chambers 6 and bonded to the flow path plate 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.

  This head is configured to pressurize the ink in the liquid chamber 6 using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric member 12, and the discharge direction of the liquid droplets is the flow direction of the recording liquid in the liquid chamber 6. The liquid droplets are ejected by different side shooter methods. By adopting the side shooter system, the size of the piezoelectric member 12 becomes substantially the size of the head, and the miniaturization of the piezoelectric member 12 can be directly linked to the miniaturization of the head, and the head can be easily miniaturized.

  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 composed of 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 a schematic cross-sectional explanatory diagram along a direction orthogonal to the nozzle arrangement direction, FIG. 6 is a principal plane explanatory diagram of a joined state in the direction along the nozzle arrangement direction, and FIGS. Similarly, the principal part front explanatory drawing of a piezoelectric member and FPC, respectively, FIG. 8 is the principal part front explanatory drawing in the joining state. Here, the description will be given of a normal pitch configuration in which all the piezoelectric columns of the piezoelectric member 12 are used as the driving column 12A except at least one piezoelectric column.

  One end (or both ends) of the piezoelectric member 12 is formed with a common electrode extraction piezoelectric column 12B which is a non-driving column having a wider width in the piezoelectric end arrangement direction (nozzle arrangement direction) than the driving column 12A (hereinafter the same). In addition, a common external electrode (common electrode portion) 25 for connecting the common external electrodes 24 of all the drive columns 12A is provided on the individual external electrode side end face of the common electrode extraction piezoelectric column 12B.

  The common external electrode 25 for extraction, the individual external electrode 23 of each drive column 12A, and the common external electrode 24 are formed at the same time as the drive column 12A and the common electrode extraction piezoelectric column 12B by groove processing by half-cut dicing. Further, the width of the drive column 12A and the width of the groove are processed so as to be substantially the same (including the same). Further, the connection between the common external electrode 25 for extraction and the common external electrode 24 of each drive column 12A is made through internal electrodes 22a and 22b that are not divided by half-cut dicing of the piezoelectric member 12.

  In the FPC 15, a plurality of individual wiring electrodes 31A and a common wiring electrode 31B are formed on a base material 30. Then, the individual wiring electrodes 31A of the FPC 15 are joined and electrically connected to the individual electrodes 23 of each drive column 12A of the piezoelectric member 12 with solder 32 which is an electrical connection member, and one end side of the piezoelectric member 12 is also connected. The common wiring electrode 31B of the FPC 15 is also joined and electrically connected to the common external electrode 25 for extraction provided on the common electrode extraction piezoelectric column 12B by the solder 32.

  In the FPC 15, a portion that is bonded to the piezoelectric member 12 side is referred to as a bonding portion 15 </ b> A, and a portion that is not bonded is referred to as a wiring portion 15 </ b> B.

  Here, as shown in FIG. 7A, the height Hb of the common electrode extraction piezoelectric column 12B is about ½ of the height Ha of the drive column 12A, and the piezoelectric column arrangement of the extraction common external electrode 25 is set. The area per unit length in the direction is the same as the area per unit length in the piezoelectric column arrangement direction of the individual external electrodes 23.

  Here, the unit length in the piezoelectric column arrangement direction is a unit length before the drive column 12A of the piezoelectric member 12 is grooved. That is, the unit length is the sum of the piezoelectric column 12 and the groove 40 provided with one electrode 23, that is, one pitch of the piezoelectric column. Here, assuming that one pitch of the piezoelectric pillars is P, the area Sa of the individual external electrode 23 is Ha × P / 2 (because the pillar width = the groove width). On the other hand, the area Sb of the common external electrode 25 for extraction is Hb × P. At this time, since the relationship is Hb = Ha / 2, Sa = Sb.

  In other words, the average height of the common external electrode 25 for extraction of the piezoelectric column 12B for common electrode extraction is the same as (height of individual external electrode × individual external electrode width / individual external electrode pitch).

  In this case, the piezoelectric column 12B for taking out the common electrode has a low height by processing the piezoelectric column after the groove processing by grinding or the like.

  On the other hand, the width of the common wiring electrode 31B of the FPC 15 is equivalent to the width of the piezoelectric column 12B for extracting the common electrode, and is wider than the individual wiring electrode 31A.

  As a method of connecting the individual external electrode 23 of the piezoelectric member 12, the common external electrode 25 for extraction, and the wiring electrodes 31A and 31B of the FPC 15, laser light is applied in a state where the FPC 15 is pressurized with a laser transmitting rigid member such as glass. Is applied to the electrode 31 and the solder 32 of the FPC 15 to melt and harden the solder 32 to use a laser bonding method. Further, the electrodes are aligned, the piezoelectric member 12 and the FPC 15 are overlapped, and the heater chip temperature is increased in pulses while the substrate 30 on the back surface of the FPC 15 is pressed with the heater chip (block) to melt the solder 32. Although a heater bonding method for bonding by curing can be used, the configuration according to the present invention is particularly effective in the case of a laser bonding method.

  The solder 32 may be any material that has a lower melting point than the electrodes 31A and 31B of the FPC 15 made of a metal member and the base material 30 of the FPC 15 and is made of a conductive material. It is preferable that it does not contain lead (Pb). For example, a solder mainly composed of tin (Sn) and bismuth (Bi) can be used as the solder 32. Since lead is not contained, it is effective from the viewpoint of environmental protection, and the solder 32 mainly composed of tin (Sn) and bismuth (Bi) has a very low melting point among non-lead members. Therefore, the electrodes 31A and 31B of the FPC 15 and the electrodes 23 and 25 of the piezoelectric member 12 can be easily welded without damaging the FPC 15 and the piezoelectric member 12.

  Here, solder is used as the electrical connection member, but an anisotropic conductive film, a conductive adhesive, or the like can also be used. Further, it can be formed in advance on the connection parts of the electrodes 23 and 25 on the piezoelectric member 12 side or the electrodes 31A and 31B of the FPC 15 by a printing method, a plating method, or the like.

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

  Next, in order to compare the configuration of the above embodiment and the configuration of the comparative example shown in FIGS. 9 and 10 in which the height of the common external electrode 25 for taking out the FPC 15 is the same as that of the individual external electrode 23, a laser bonding method is used. The individual external electrode 23 of the piezoelectric member 12, the common external electrode 25 for extraction, and the electrodes 31A and 31B of the FPC 15 were connected.

  As a result, in the configuration of the present embodiment, the common external electrode 25 for taking out the piezoelectric column 12B and the FPC 15 have a laser irradiation condition in which the solder of the individual external electrode 23 of the drive column 12A and the individual wiring electrode 31A of the FPC 15 can be melted and bonded. The common wiring electrode 31B can be bonded, and the bonding failure of the electrode of the piezoelectric member 12 and the FPC 15 and the damage of the FPC base material did not occur, and the bonding was possible.

  On the other hand, in the configuration of the comparative example, the individual external electrodes 23 could be joined without any problem under the same laser irradiation conditions as in the configuration of the present embodiment, but the common external electrode 25 for extraction could be joined without the solder melting well. There wasn't. Further, when the individual external electrodes 23 are joined under irradiation conditions that allow the solder of the common external electrode 25 for extraction to be melted, the expansion / contraction of the FPC base material is increased, resulting in poor jointing and partial damage to the FPC base material. .

  In the present embodiment, the height Hb of the common electrode extraction piezoelectric column 12B is about ½ of the height Ha of the drive column 12A, and the unit length of the extraction common external electrode 25 per unit length in the piezoelectric column arrangement direction is set. The area is the same as the area per unit length in the piezoelectric column arrangement direction of the individual external electrodes 23 (the average height of the common external electrodes 25 for extracting the piezoelectric columns 12B is the height of the individual external electrodes × the individual external electrode width / individual The same as the external electrode pitch), but it can be reduced to 1/2 or less if there are no defects such as bonding failure due to expansion / contraction of the wiring member, damage to the wiring member due to overheating, and significant reduction in production efficiency. .

  Thus, since the area per unit length in the piezoelectric column arrangement direction of the common external electrode for extraction is not more than the area per unit length in the piezoelectric column arrangement direction of the individual external electrode, the common external electrode for extraction and the individual external electrode Can be connected to the electrode of the wiring member under the same conditions, and poor connection of the electrode between the piezoelectric member and the wiring member and damage to the piezoelectric member and the wiring member can be reduced.

  Further, by setting the average height of the common external electrodes for taking out the piezoelectric members to be equal to or less than (the height of the individual external electrodes × the width of the individual external electrodes / the pitch of the individual external electrodes), the piezoelectric members are not lengthened in the pitch direction. Since the drive current flows as in the conventional case, the width of the common external electrode for taking out the piezoelectric member can be secured widely. That is, it is not necessary to increase the size of the piezoelectric member or the wiring member, and the cost of the member can be suppressed as in the conventional case.

  Moreover, since the width of the common electrode extraction piezoelectric column at the outermost end of the piezoelectric member can be increased, the strength of the piezoelectric column can be maintained. That is, damage at the time of connecting the piezoelectric member and the wiring member or at the time of other assembly can be reduced.

  In addition, as described above, by setting the area per unit length in the piezoelectric column arrangement direction of the common external electrode for extraction to be equal to or less than the area per unit length in the piezoelectric column arrangement direction of the individual external electrode, a heater chip, a laser, etc. The amount of heat of the heating tool can be uniformly applied to the common external electrode and the individual external electrode, and the excess amount of heat can be reduced.

  That is, since the connection failure between the electrodes of the piezoelectric member and the wiring member and the damage of the piezoelectric member and the wiring member can be reduced with a simple configuration, the equipment cost and the heating time can be shortened.

  As described above, the area per unit length in the piezoelectric column arrangement direction of the common external electrode for extraction is equal to or less than the area per unit length in the piezoelectric column arrangement direction of the individual external electrode, or the common external electrode for extraction The average height of each of the electrodes is equal to or less than (the height of the individual external electrodes × the width of the individual external electrodes / the pitch of the individual electrodes). An increase in tact time when joining the wiring member to the utility pole can be prevented and joining can be performed in a short time.

Next, a second embodiment of the present invention will be described with reference to FIG. In addition, FIG. 11 is a principal front explanatory view of the joined state of the piezoelectric member and the wiring member in the same embodiment.
In the present embodiment, the joint end (tip: wiring electrode end) 31Ba of the common wiring electrode 31B of the FPC 15 is formed obliquely in a direction that becomes lower toward the outer end side in the piezoelectric column arrangement direction of the piezoelectric member 12. .

  Here, as in the first embodiment, the individual external electrode 23 and the extraction common external electrode 25 of the piezoelectric member 12 and the electrodes 31A and 31B of the FPC 15 were connected using a laser bonding method.

  At this time, the joining end 31Aa of the individual wiring electrode 31A of the FPC 15 is located between the tip height position of the common external electrode 12B for extraction and the tip height position of the individual external electrode 23.

  Further, the driving column side one end portion 35a of the joint end 31Ba of the common wiring electrode 31B of the FPC 15 is located between the tip height position of the common external electrode 25 for extraction and the tip height position of the individual external electrode 23.

  On the other hand, among the joint ends 31Ba of the common wiring electrode 31B of the FPC 15, the other end portion on the end portion side of the piezoelectric member 12, that is, the corner portion (the upper left corner portion in FIG. 11) 35b located on the outer side in the piezoelectric column arrangement direction, It is located closer to the base of the column than the tip position of the common external electrode for extraction. That is, the corner portion 35b of the joint end 31Ba of the common wiring electrode 31B is joined (connected) so as to overlap the extraction common external electrode 25.

  In the configuration of the present embodiment, the common external electrode 25 for taking out the piezoelectric member 12 and the common wiring electrode for the FPC 15 under the laser irradiation condition that the solder of the individual external electrode 23 of the piezoelectric member 12 and the individual wiring electrode 31A of the FPC 15 can be melted and joined. 31B could be joined, and the electrical joining failure between the piezoelectric member and the wiring member and the damage of the FPC base material did not occur, and good joining was obtained.

  In this way, the connection end of the wiring member is positioned between the height position of the common external electrode portion for taking out the piezoelectric member and the height position of the individual external electrode, thereby enabling the individual external with a narrow electrode width. Even in the case of an electrode, the bonding area with the wiring electrode can be made larger than that in the first embodiment, and the bonding reliability in the individual external electrode portion can be improved.

  In addition, the joint end of the wiring electrode of the wiring member is between the height position of the common external electrode for taking out the piezoelectric member and the height position of the individual external electrode, and at least the outer side of the common external electrode for taking out in the piezoelectric column arrangement direction The corner portion of the common wiring electrode does not protrude from the piezoelectric member by being configured to be lower than the height position of the common external electrode for extracting the piezoelectric member (on the base side from the tip position) It is possible to prevent the wiring member from being caught and damaged by a jig or the like at the time of joining or other assembly.

  In the present embodiment, the joint end 31Ba of the common wiring electrode 31 is formed obliquely, so that the corner portion 35b located outside in the piezoelectric column arrangement direction is closer to the base of the column than the distal end position of the common external electrode 25 for extraction. Although it is set as the structure located in the side, the same effect can be acquired also by making junction end 31Ba into step shape (shape which provided the level | step difference).

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 12 is an explanatory front view of a main part in a joined state of the piezoelectric member and the wiring member in the same embodiment.
In the present embodiment, the height Hb1 of the portion 12Bb on the outer side in the piezoelectric column arrangement direction of the piezoelectric column 12B for common electrode extraction is made the same as the height Ha of the driving column 12A, and other portions of the piezoelectric column 12B for common electrode extraction are used. The height Hb2 is set to 1/3 of the height Ha of the drive column 12A.

  Then, similarly to the first embodiment, the individual external electrode 23 and the extraction common external electrode 25 of the piezoelectric member 12 and the electrodes 31A and 31B of the FPC 15 were connected using a laser bonding method.

  In the present embodiment, the extraction external common electrode 25 of the piezoelectric member 12 and the common wiring electrode 31B of the FPC 15 are provided under the laser irradiation conditions in which the solder of the individual external electrode 23 of the piezoelectric member 12 and the individual wiring electrode 31A of the FPC 15 can be melted and joined. As a result, no defective bonding of the electrode between the piezoelectric member 12 and the FPC 15 as the wiring member or damage to the FPC base material occurred, and good bonding was obtained.

  By configuring in this way, even with an individual external electrode with a narrow electrode width, the bonding area with the wiring electrode can be made wider than that of the first embodiment, and the bonding reliability in the individual external electrode portion can be improved. it can.

  Further, the corner portion of the common wiring electrode does not protrude from the piezoelectric member, and it is possible to prevent the wiring member from being caught and damaged by a jig or the like at the time of joining or other assembly.

  Furthermore, the outermost end of the piezoelectric member can be joined to the diaphragm member at the same height as the drive column, and the joining reliability with the diaphragm member is also improved.

  Here, the common wiring bulb 31A of the FPC 15 is joined only in the region where the height of the extraction common external electrode 25 is low (the region of the height Hb2). If troubles such as a significant reduction in production efficiency do not occur, it is possible to join including the region where the common external electrode 25 for extraction is high (region of height Hb1).

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 13 is an explanatory front view of the main part of the bonded state of the piezoelectric member and the wiring member in the same embodiment.
In the present embodiment, a part of the common electrode extraction piezoelectric column 12B having the same height Hb1 as the height Ha of the drive column 12A in the third embodiment on the outer side in the piezoelectric column arrangement direction is a common electrode extraction piezoelectric column 12B. And a different piezoelectric column (non-driven column) 12C.

  Then, similarly to the first embodiment, the individual external electrode 23 and the extraction common external electrode 25 of the piezoelectric member 12 and the electrodes 31A and 31B of the FPC 15 were connected using a laser bonding method.

  In the present embodiment, the extraction external common electrode 25 of the piezoelectric member 12 and the common wiring electrode 31B of the FPC 15 are provided under the laser irradiation conditions in which the solder of the individual external electrode 23 of the piezoelectric member 12 and the individual wiring electrode 31A of the FPC 15 can be melted and joined. As a result, no defective bonding of the electrode between the piezoelectric member 12 and the FPC 15 as the wiring member or damage to the FPC base material occurred, and good bonding was obtained.

  By configuring in this way, the same effect as the third embodiment can be obtained. Compared with the third embodiment, the piezoelectric column 12C can be formed by grooving by half-cut dicing or the like instead of cutting a part of the common electrode extracting piezoelectric column 12B. become.

  Next, an example of an image forming apparatus equipped with the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 14 is an explanatory side view of the mechanism of the apparatus, and FIG. 15 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, piezoelectric column for common electrode extraction)
13 Base member 15 FPC (wiring member)
23 Individual external electrode 25 Common external electrode for extraction 31A Individual wiring electrode (connection electrode)
31B Common wiring electrode (connection electrode)
32 ... Solder member 234 ... Carriage 235 ... Recording head

Claims (7)

A plurality of piezoelectric columns arranged corresponding to a plurality of individual liquid chambers through which nozzles for discharging droplets communicate;
At least one common electrode take-out piezoelectric column that does not correspond to the individual liquid chamber and has a wider width in the piezoelectric column arrangement direction than the plurality of piezoelectric columns;
A wiring member for providing a drive signal to the plurality of piezoelectric pillars,
The plurality of piezoelectric pillars are provided with individual external electrodes and common external electrodes,
The common electrode extraction piezoelectric column is provided with a common external electrode for extraction that leads to a common external electrode of the plurality of piezoelectric columns,
The individual external electrode is connected to an individual wiring electrode provided on the wiring member by an electrical connection member,
A common wiring electrode provided on the wiring member by an electrical connection member is connected to the common external electrode for extraction,
The liquid discharge head according to claim 1, wherein an area per unit length in the piezoelectric column arrangement direction of the common external electrode for extraction is equal to or less than an area per unit length in the piezoelectric column arrangement direction of the individual external electrode. A plurality of piezoelectric columns arranged corresponding to a plurality of individual liquid chambers through which nozzles for discharging droplets communicate;
At least one common electrode take-out piezoelectric column that does not correspond to the individual liquid chamber and has a wider width in the piezoelectric column arrangement direction than the plurality of piezoelectric columns;
A wiring member for providing a drive signal to the plurality of piezoelectric pillars,
The plurality of piezoelectric pillars are provided with individual external electrodes and common external electrodes,
The common electrode extraction piezoelectric column is provided with a common external electrode for extraction that leads to a common external electrode of the plurality of piezoelectric columns,
The individual external electrode is connected to an individual wiring electrode provided on the wiring member by an electrical connection member,
A common wiring electrode provided on the wiring member by an electrical connection member is connected to the common external electrode for extraction,
An average height of the common external electrode for extraction is equal to or less than (height of individual external electrode × individual external electrode width / individual electrode pitch).   3. The liquid discharge according to claim 1, wherein a joint end of each wiring electrode of the wiring member is located between a tip position of the common external electrode for extraction and a tip position of the individual external electrode. head. The joint end of the individual wiring electrode of the wiring member is located between the tip position of the common external electrode for extraction and the tip position of the individual external electrode,
Of the joint ends of the common wiring electrodes of the wiring member, at least a corner portion located outside in the piezoelectric column arrangement direction is located closer to the base side of the column than the tip position of the common external electrode for extraction. The liquid discharge head according to claim 1.   3. The liquid ejection head according to claim 1, wherein a height of a part of the piezoelectric column for extracting the common electrode is the same as a height of the plurality of piezoelectric columns.   3. The liquid ejection head according to claim 1, wherein a piezoelectric column having the same height as the plurality of piezoelectric columns is provided on the outer side in the piezoelectric column arrangement direction than the piezoelectric column for taking out the common electrode.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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