JP2013230591A - High-density liquid ejection head for image formation, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-density liquid ejection head for image forming in which a piezoelectric element, an input terminal of a driving IC and an FPC board are connected by wire bonding in a state where a high level difference does not exist, and whose actuator substrate is miniaturized, thereby achieving reduction in cost, and to provide an image forming apparatus.SOLUTION: A nozzle plate 5 includes an extension part 5a whose edge part side provided with input terminals (9a, 10a, 11a, 12a and 13) of a diaphragm 7 is formed to be larger than an actuator substrate 1. A wiring end 18a provided with a wiring terminal 19, of a flexible wiring board (FPC18) is fixed on the extension part 5a, and a controller (driving IC 15), the input terminals (9a, 10a, 11a, 12a and 13) of a thin-film-like piezoelectric element (piezoelectric element 8) and the wiring terminal 19 of the flexible wiring board (FPC18) are connected by wire bonding.

Description

  The present invention relates to a high-density liquid ejection head for image formation and an image forming apparatus.

  2. Description of the Related Art Conventionally, for example, there are image forming apparatuses such as printers, facsimiles, copying machines, plotters, and the like, and image forming apparatuses such as multifunction machines having two or more functions of printers, facsimiles, and copying machines.

  As such various image forming apparatuses, there are known liquid droplet ejection apparatuses that are equipped with a liquid ejection head that ejects a recording liquid and form an image on a recording medium (usually called a recording medium). As this liquid ejection head, for example, an ink jet head (ink jet) provided with a piezoelectric element as an actuator (pressure generating means) for generating a pressure to pressurize the liquid chamber, and a liquid chamber supplied with liquid ink Recording heads) are known.

  By the way, inkjet printers (droplet ejection devices) equipped with such an inkjet head have recently been able to handle high-quality, low-cost, high-speed compatibility (by increasing or decreasing the number of nozzles, from fast printers to slow but cheap printers). However, further improvement in image quality, cost reduction, and downsizing have been demanded.

  For this reason, MEMS (MicroElectroMechanical Systems) processing technology is incorporated in the inkjet head. This processing technique is a fine processing technique using a semiconductor process.

  When an inkjet head (droplet discharge head) is formed by this MEMS processing technology, for example, processing such as etching and sputtering of components such as a liquid chamber, a diaphragm, a piezoelectric element, and an electrode necessary for the inkjet head on a silicon substrate. It can be formed by a method. By this processing, the inkjet head can be made small by forming each component or part of the inkjet head small, or by devising the arrangement of each component.

  As a result, a large number of inkjet heads can be made from a single silicon substrate (increase the number). And since an inkjet head can reduce cost, so that it miniaturizes, it is desirable to reduce in size.

  In order to reduce the size of the ink jet head, in addition to the miniaturization of each component described above, it is necessary to make the mounting area of the drive IC and the input terminal joint for driving the piezoelectric element provided in the ink jet head compact (small). is there.

  As a measure for reducing the drive IC mounting portion in this ink jet head, when joining the drive IC and a piezoelectric element as an actuator, or joining an FPC (Flexible Printed Circuit) having a drive IC and an input terminal, a wire It has been proposed to connect by bonding (see, for example, Patent Document 1).

  In addition, as another inkjet head, a liquid chamber hole opening on both sides is formed in the nozzle substrate body, and one surface side of the liquid chamber hole is closed with a nozzle plate. By closing the surface side with a diaphragm, the hole for the liquid chamber is used as a pressure generating chamber, and a reinforcing plate in which a wiring space is formed in a portion corresponding to the pressure generating chamber is laminated and fixed on the diaphragm. There is known an ink jet recording head in which an actuator piezoelectric element for generating a pressurizing force positioned in the wiring space is provided on a diaphragm (for example, see Patent Document 2).

  However, in the ink jet head (droplet discharge head) of Patent Document 1, a liquid such as ink in the liquid chamber provided on the liquid chamber substrate is provided so that it can be dropped from a lower nozzle, and is closed at the upper end of the liquid chamber. A piezoelectric element is provided on the plate, and a thick liquid supply substrate and a frame substrate are sequentially attached to the upper portion of the vibration plate, and a drive IC is provided on the frame substrate. For this reason, in this ink jet head, a high step is formed between the drive IC and the piezoelectric element, or between the drive IC and the FPC, and therefore, between the drive IC and the piezoelectric element or between the drive IC and the FPC. The joining was performed between the high step portions.

  For this reason, when bonding the driving IC and the piezoelectric element with a wire using a bonding tool, or when bonding the driving IC and the FPC with a wire, the bonding tool and the wire do not come into contact with each other, or the wire should not come into contact with other parts. There was a problem in the stability of control to form a simple wire loop. For this reason, in the inkjet head of patent document 1, there exists a limit in narrowing a bonding pitch, and it was difficult to make the nozzle pitch of an inkjet head high-density, and size reduction was difficult.

  Further, in the ink jet recording head of Patent Document 2, it has been proposed that an FPC (flexible wiring board) is bonded and fixed to the upper surface of a reinforcing plate, and the FPC and the diaphragm are connected by wire bonding. However, even with this ink jet recording head, since the FPC and the diaphragm are joined between the high step portions, the size cannot be reduced.

  Therefore, the present invention can connect the input terminal of the piezoelectric element or the driving IC and the FPC by wire bonding without a high step, and can reduce the cost by reducing the size of the actuator substrate. An object of the present invention is to provide a liquid discharge head and an image forming apparatus.

  In order to achieve this object, the present invention provides an actuator substrate having a plurality of liquid chambers, a liquid chamber provided on one surface side of the actuator substrate, closing one end of the liquid chamber, and liquids in the plurality of liquid chambers. Corresponding to each of the liquid chambers, a nozzle plate provided with a plurality of nozzles for discharging each of the above, a thin-film vibrating plate fixed to the other surface of the actuator substrate and closing the other end of the liquid chamber, A plurality of thin film piezoelectric elements that are provided on the diaphragm and generate pressure to pressurize the liquid in each liquid chamber, and the plurality of thin film piezoelectric elements are driven via input terminals provided on the diaphragm. A high-density liquid discharge head comprising a control device for controlling and a flexible wiring substrate for wiring connection connected to the input terminal, wherein the nozzle plate is on the edge side provided with the input terminal of the diaphragm An extension portion formed larger than the actuator substrate, and a wiring end portion provided with a wiring terminal of the flexible wiring substrate is fixed on the extension portion, and the control device and the input terminal of the thin film piezoelectric element And wiring terminals of the flexible wiring board are connected by the wire bonding.

  According to this configuration, the input terminal of the piezoelectric element or drive IC and the flexible wiring board can be connected by wire bonding without a high step, and the actuator board can be reduced in size and cost can be reduced.

It is sectional drawing of the Example which applied the high-density liquid discharge head which concerns on this invention to the inkjet head of 2 rows of nozzle rows. It is a top view of the inkjet head which abbreviate | omitted the flame | frame, diaphragm, and FPC of FIG. It is a top view of the inkjet head which abbreviate | omitted the upper frame of FIG. It is sectional drawing which follows the A1-A1 line | wire of FIG. It is sectional drawing which follows the A2-A2 line | wire of FIG. It is sectional drawing which follows the A3-A3 line | wire of FIG. It is a top view of the inkjet head which abbreviate | omitted the flame | frame of FIG. FIG. 7 is an enlarged explanatory view of a connection portion between an input terminal and an FPC wiring terminal provided on the diaphragm of FIG. 6. It is sectional drawing of Example 2 which applied the high-density liquid discharge head based on this invention to the inkjet head. It is a top view which shows Example 3 of the inkjet head which provided FPC of FIG. 2A in the both ends. FIG. 10 is a cross-sectional view of the ink jet head of FIG. 9, similar to the cross section of FIG. FIG. 10 is a cross-sectional view of the ink jet head of FIG. 9, similar to the cross section of FIG. FIG. 10 is a cross-sectional view of the ink jet head of FIG. 9, similar to the cross section of FIG. FIG. 10 is a plan view similar to FIG. 6 of the first embodiment, which is the ink jet head of FIG. 9. FIG. 12 is a cross-sectional view similar to FIG. 2 of the first embodiment in which the lower frame and the diaphragm of the ink jet head of FIGS. 9 to 11 are omitted. (A) is a schematic side view of the principal part of Example 4 which applied the high-density liquid discharge head based on this invention to the inkjet head, (b) is a top view of (a). (A) is a schematic side view of an essential part of Example 5 in which the high-density liquid ejection head according to the present invention is applied to an ink jet head, (b) is a plan view of (a), and (c) is an essential part of (b). FIG. It is a schematic explanatory drawing of the image forming apparatus of Example 6 to which the high-density liquid discharge head (inkjet head) which concerns on this invention is applied. FIG. 18 is a schematic plan view showing the relationship between the high-density liquid ejection head (inkjet head) of FIG. 17 and the operation direction.

  Embodiments of a high-density liquid discharge head and an image forming apparatus using the same according to the present invention will be described below with reference to the drawings.

A first embodiment of a high-density liquid ejection head according to the present invention will be described below with reference to FIGS.
[Constitution]
A. Basic Configuration FIG. 1 is a cross-sectional view of an embodiment in which the high-density liquid discharge head according to the present invention is applied to an inkjet head having two nozzle rows. FIG. 2 is a plan view of the ink jet head in which the frame, the diaphragm, and the FPC in FIG. 1 are omitted. FIG. 2A is a plan view of the inkjet head from which the upper frame of FIG. 1 is omitted. 3 is a cross-sectional view taken along line A1-A1 in FIG. 1, FIG. 4 is a cross-sectional view taken along line A2-A2 in FIG. 1, and FIG. 5 is a cross-sectional view taken along line A3-A3 in FIG. 6 is a plan view of the ink jet head from which the frame of FIG. 1 is omitted, and FIG. 7 is an enlarged explanatory view of a connection portion between the input terminal provided on the diaphragm of FIG. 6 and the wiring terminal of the FPC.

  Although the configuration of the first embodiment is described as an example applied to an inkjet head having two nozzle rows, the present invention can be similarly applied to an inkjet head having more than two nozzle rows.

  In FIG. 1, reference numeral 1 denotes an actuator substrate made of a laminated body of glass or a thin metal plate, a silicon substrate, or the like. The actuator substrate 1 is preferably made of a silicon substrate. When the actuator substrate 1 is made of a silicon substrate or the like, the plurality of liquid chambers 2 can be formed by etching the silicon substrate.

  As shown in FIG. 1, the actuator substrate 1 is formed with a plurality of liquid chambers 2 that are open on both sides (the upper surface and the lower surface of the actuator substrate 1 in FIG. 1). As shown in FIG. 2, each of the liquid chambers 2 is elongated in a straight line in the short direction of the actuator substrate 1 (left and right direction in FIG. 2).

  As shown in FIGS. 2 and 3, the plurality of liquid chambers 2 are first liquids arranged in a straight line at an equal pitch in the longitudinal direction of the actuator substrate 1 (vertical direction in FIG. 2, horizontal direction in FIG. 3). 2 and 4, as shown in FIGS. 2 and 4, the second liquid chamber row Lq2 arranged linearly at an equal pitch in the longitudinal direction of the actuator substrate 1 (vertical direction in FIG. 2, horizontal direction in FIG. 4). Is configured. In addition, the first and second liquid chamber rows Lq1 and Lq2 are arranged in two rows (parallelly arranged in the short direction) toward the short side direction (left and right direction in FIG. 2) of the actuator substrate 1. Here, the side edges in the short direction of the actuator substrate 1 are denoted by 1a and 1b as shown in FIGS.

  A plurality of individual flow paths 3 corresponding to the liquid chambers 2 of the first and second liquid chamber rows Lq1 and Lq2 and opened on both surfaces of the actuator substrate 1 are provided on the side edge portions 1a and 1b of the actuator substrate 1, respectively. Are formed respectively. The side edges 1a and 1b are formed with a plurality of notch-shaped individual communication passages 4 that open to one surface side of the actuator substrate 1 and communicate with the individual flow paths 3 and the liquid chambers 2, respectively. .

  The individual communication passage 4 on the first liquid chamber row Lq1 side and the individual communication passage 4 on the second liquid chamber row Lq2 side are the elongated liquid chamber 2 in the first liquid chamber row Lq1 and the elongated liquid in the second liquid chamber row Lq2. The chambers 2 communicate with portions of the chamber 2 opposite to each other.

The individual communication path 4 is formed in a small cross-sectional area, and restricts the flow rate of the liquid flowing from the individual flow path 3 to the liquid chamber 2. When the actuator substrate 1 is made of a silicon substrate or the like, the liquid chamber 2, the individual flow path 3, the individual communication path 4 and the like can be formed by etching.
(Nozzle plate 5, nozzle 6)
As shown in FIG. 1, each liquid chamber 2, the individual flow path 3, and the individual communication path 4 are joined to one surface of the actuator substrate 1 at the open end to the one surface side (the lower surface side in FIG. 1). Closed by the (fixed) nozzle plate 5.

  The nozzle plate 5 is made of a resin or metal material, and a plurality of nozzles 6 communicating with the liquid chambers 2 are formed on the nozzle plate 5 as shown in FIGS. . As shown in FIG. 2, the plurality of nozzles 6 are arranged in two rows in the short direction (left and right direction in FIG. 2) of the actuator substrate 1, and two rows 6 arranged in parallel in the short direction. The first and second nozzle rows Nz1, Nz2 are configured (formed).

The nozzle 6 of the first nozzle row Nz1 and the nozzle 6 of the second nozzle row Nz2 are positioned adjacent to the first liquid chamber row Lq1 and the second liquid chamber row Lq2, as shown in FIGS. It has been. That is, the nozzle 6 of the first nozzle row Nz1 and the nozzle 6 of the second nozzle row Nz2 are the end portions of the liquid chamber 2 of the first liquid chamber row Lq1 and the liquid chamber 2 of the second liquid chamber row Lq2 on the adjacent sides. Communicating with
(Vibration plate 7)
In the present embodiment, the other surface side end portion of the actuator substrate 1 of the liquid chamber 2 is closed by a thin film diaphragm 7 provided on the other surface of the actuator substrate 1. The diaphragm 7 is formed from a SiO ₂ layer of an SOI (Silicon On Insurator) substrate. Further, when the actuator substrate 1 is formed of a support substrate of a laminated body of glass or a thin metal plate as described above, the actuator substrate 1 and a separate SOI substrate are bonded or bonded to the actuator substrate 1 and bonded together. By polishing this SOI substrate into a thin film, the thin film SOI substrate can be used as the diaphragm 7.

  In addition, even when the actuator substrate 1 is made of a silicon substrate or the like as described above, an SOI substrate separate from the actuator substrate 1 is bonded or bonded to the actuator substrate 1 and bonded together, and the SOI substrate is thin-film-shaped. The thin film SOI substrate can be used as the diaphragm 7 by polishing the substrate.

If the actuator substrate 1 is made of a silicon substrate or the like as described above, a portion of the silicon substrate where the SiO ₂ layer is not formed is formed by forming a thin-film SiO ₂ layer on one surface of the silicon substrate. An actuator substrate body (support substrate) can also be used. This actuator substrate body is the actuator substrate 1 in FIG.

When the silicon substrate is etched from the other side to form a plurality of liquid chambers 2, the SiO ₂ layer can be used as an etching stop layer. By forming the liquid chamber 2, a thin SiO ₂ layer can be formed on one surface of the silicon substrate as the diaphragm 7 in FIG. By making the diaphragm 7 into a thin film diaphragm formed of Si _N (SiO ₂ ) or the like in this way, the cost is lower than that of the SOI substrate, so that the cost can be reduced. When the actuator substrate 1 is formed from a silicon substrate, the diaphragm 7 can be formed integrally with the actuator substrate 1.

As shown in FIG. 1, the diaphragm 7 is formed with a communication path 7 p corresponding to the individual flow path 3 and corresponding to the individual flow path 3.
(Piezoelectric element 8, wiring)
As shown in FIG. 1, a thin film PZT [that is, Pb (ZrTi) formed on the surface of the diaphragm 7 opposite to the liquid chamber 2 by a processing method such as sputtering or a sol-gel method. O ₃ ] is provided as a thin film piezoelectric element (thin film piezoelectric element) 8. However, although the thin film piezoelectric element (thin film piezoelectric element) 8 is formed from the thin film PZT here, the piezoelectric element 8 may be a piezoelectric element other than PZT.

  The piezoelectric element 8 is an actuator that expands and contracts when an alternating voltage is applied to vibrate the diaphragm 7 and applies pressure to the liquid chamber 2 by the diaphragm 7. Further, as shown in FIGS. 5 and 6, the plurality of piezoelectric elements 8 are linearly arranged in two rows, and constitute (form) two rows of first and second piezoelectric element rows Pz1 and Pz2. doing. Here, in FIG. 6, 7 a and 7 b are side edges of the diaphragm 7 opposite to each other in the juxtaposition direction of the first and second piezoelectric element arrays Pz 1 and Pz 2, and 7 c is the first and second piezoelectric elements of the diaphragm 7. It is an end in the extending direction of the element rows Pz1, Pz2.

  As shown in FIG. 6, on the surface of the diaphragm 7 opposite to the liquid chamber 2, a first Com wiring (that is, a first Com pattern wiring) 9 extending along the side edge portion 7a and the end portion 7c, A second Com wiring (that is, a second Com pattern wiring) 10 extending along the edge 7b and the end 7c is formed by etching or the like. Each piezoelectric element 8 of the first piezoelectric element array Pz1 is connected to the first Com wiring 9, and each piezoelectric element 8 of the second piezoelectric element array Pz2 is connected to the second Com wiring 10.

  Further, an input terminal 9 a branched from the first Com wiring 9 and an input terminal 10 a branched from the second Com wiring 10 are formed at the end 7 c of the diaphragm 7. Further, Vcom wirings 11 and 12 are formed at the end 7c of the diaphragm 7 between the first Com wiring 9 and the second Com wiring 10, and a plurality of inputs branch from the Vcom wirings 11 and 12. Terminals 11a and 12a are formed. A plurality of input terminals 13 positioned between the input terminals 11 a and 12 a are formed at the end 7 c of the diaphragm 7.

The plurality of liquid chambers 2, nozzles 6 and piezoelectric elements (thin film-like piezoelectric elements) 8 correspond to those shown in FIG. 1, FIG. 3 and FIG. ). A plurality of liquid discharge head portions are provided corresponding to each liquid chamber 2 and are arranged in two lines in a straight line, and two rows of first and second liquid discharge head portion rows (reference numerals omitted). ) Is formed (formed).
(Lower frame plate 14)
As shown in FIGS. 1, 3, and 4, a lower frame plate (subframe) 14 is joined (fixed) on the diaphragm 7. The lower frame plate 14 is formed with a plurality of vibration allowing recesses 14a facing the piezoelectric elements 8 of the first and second piezoelectric element rows Pz1 and Pz2. The plurality of vibration allowing recesses 14 a are linear and have the same shape as the elongated liquid chamber 2, and are provided so as to coincide with the respective liquid chambers 2.

As shown in FIGS. 1 and 2A, the lower frame plate 14 is provided with an arrangement space 14b that is located between the first and second piezoelectric element rows Pz1 and Pz2 and that opens on the upper and lower surfaces. A drive IC 15 fixed on the diaphragm 7 is disposed as a control device (control unit) in 14b. The drive IC 15 is wired to one end of each piezoelectric element 8 so as to drive and control the piezoelectric element 8 on the diaphragm 7 and is wired to the input terminals 11a, 12a, and 13.
(Upper frame plate 16)
Further, as shown in FIG. 1, an upper frame plate (upper frame) 16 is bonded (fixed) on the lower frame plate 14. As shown in FIG. 1, the lower frame plate 14 and the upper frame plate 16 are formed on the opposite side edge portions so as to straddle the lower frame plate 14 and the upper frame plate 16, and the first and second piezoelectric elements. First and second common liquid chambers 17a and 17b are formed on the opposite sides of the element rows Pz1 and Pz2, respectively. The first and second common liquid chambers 17a and 17b extend along the arrangement direction of the individual flow paths 3 as shown in FIG. 2A. Further, as shown in FIG. 1, the portions corresponding to the first and second piezoelectric element rows Pz1 and Pz2 of the upper frame plate 16 are respectively connected to the first and second common liquid chambers 17a and 17b. Mouth 16a, 16b is formed. The supply ports 16a and 16b are provided in the upper frame plate 16 so as to be positioned at substantially the center or the end side in the extending direction of the first and second piezoelectric element rows Pz1 and Pz2, for example.
(Bonding club)
The nozzle plate 5 is formed such that the dimension in the extending direction of each of the first and second nozzle arrays Nz1 and Nz2 (that is, the arrangement direction of the nozzles 2 in the first and second nozzle arrays Nz1 and Nz2) is larger than the dimension of the actuator substrate 1. Has been. As a result, the extended portions 5a projecting from the end of the actuator substrate 1 are provided on both ends of the nozzle plate 5 in the extending direction of the first and second nozzle rows Nz1 and Nz2, as shown in FIGS. (The other not shown) is formed as a protruding end.

  On the extended portion 5a, a wiring end 18a of a FPC (flexible wiring board) 18 for wiring connection is disposed. A plurality of wiring terminals 19 are arranged in parallel on the surface of the wiring end 18a. Further, as shown in FIGS. 3 and 4, a backing plate 20 is fixed to the back surface of the wiring end portion 18a. By fixing the backing plate 20 to the extended portion 5a, the wiring end 18a of the FPC 18 is attached on the extended portion 5a.

The plurality of wiring terminals 19 of the wiring end portion 18a are bonded to the plurality of input terminals 11a, 12a, and 13 provided on the diaphragm 7 by bonding wires 21 (wire bonding).
[Action]
Next, other configuration conditions and operations of the inkjet head which is the high-density liquid ejection head having such a configuration will be described.
(1). Other constituent conditions of the inkjet head which is a high-density liquid discharge head For the lower electrode, the upper electrode, and the necessary insulating layer for applying a voltage to the piezoelectric element 8, a commonly used general technique In order to avoid complication, the description is omitted here.

  As described above, the lower frame plate 14 made of resin, silicon substrate, metal, or the like surrounding the piezoelectric element 8 is surrounded by an adhesive on the vibration plate 7 of the actuator substrate 1 as a subframe. It is joined and provided. As described above, the diaphragm 7 is preferably formed from a silicon substrate or the like, similarly to the actuator substrate 1.

  As the lower frame plate 14 which is a subframe, a silicon substrate which has preferably processing accuracy, has the same thermal expansion coefficient as that of the diaphragm 7 and can be freely selected in thickness is the best.

  Further, the upper frame plate 16 for forming the common liquid chambers (17a, 17b) is adhesively bonded to the lower frame plate 14 as a subframe with an adhesive as described above.

  A vibration plate 7 is disposed on the actuator substrate 1, and a driving IC 15 for driving the piezoelectric element 8 is flip-chip mounted on the vibration plate 7.

An input signal to the driving IC 15 and an analog terminal for driving the piezoelectric element are joined via an FPC (flexible printed circuit board) 18.
<Individual configuration and function>
As described above, a plurality of nozzles 6 that discharge liquid, the liquid chamber 2 that communicates with the nozzle 6, and an actuator (piezoelectric element 8) that generates pressure to pressurize the liquid in the liquid chamber 2 are provided. In the high-density liquid ejection head, the diaphragm 7 is formed in a thin film on the actuator substrate 1, and the actuator (piezoelectric element 8) is formed in a thin film on the diaphragm 7, and the driving IC 15 is formed on the diaphragm 7. Is flip-chip mounted.

  Here, the drive IC 15 is flip-chip mounted on the vibration plate 7 of the actuator substrate 1. However, heat generated from the piezoelectric element and the drive IC 15 is easily transmitted to the ink through the vibration plate 7 and the actuator substrate 1. .

  However, since the heat is discharged by the ejected ink during normal printing, the temperature rise of the head portion can be suppressed.

  A process flow when the actuator substrate 1 and the diaphragm 7 are integrally formed from a silicon substrate will be briefly described. In this case, the portion including the actuator substrate 1 and the diaphragm 7 can also be referred to as an actuator substrate, the portion indicated by 1 can be referred to as a silicon substrate portion, and the portion indicated by 7 can be referred to as a vibration thin film. it can.

  After the diaphragm 7, various electrodes, and the piezoelectric element 8 are formed on the actuator substrate 1 having a thickness of 400 μm, the lower frame plate 14, which is a 400 μm-thick subframe processed into a predetermined shape, is bonded to the diaphragm 7.

  The actuator substrate 1 is polished to a thickness corresponding to the height of the individual liquid chamber using the lower frame plate 14 as a subframe as a reference. In this example, polishing was performed to a thickness of 80 μm.

  After polishing, the actuator substrate 1 is etched to form individual liquid chambers 2, individual liquid chamber communication portions (individual flow path 3, individual communication path 4), and the like. Thereafter, division processing is performed by dicing or the like, and individual chips are formed and assembled to form a head.

  By reducing the size of the actuator substrate 1 to which the lower frame plate 14 as the subframe is joined, the number of chips that can be taken from the Si wafer can be increased, and the cost can be reduced.

  This size reduction of the chip can be achieved by reducing the size of the individual liquid chambers based on the ejection characteristics, and thus reducing the size of the driving IC mounting portion and the FPC mounting portion connected to the head input terminal.

The mounting portion of the driving IC 15 can be achieved by downsizing the driving IC 15, but since the on-resistance in the driving IC 15 increases due to the downsizing and the influence of heat generation during driving becomes a problem, a design study becomes important. Come.
(2) Operation of inkjet head which is high-density liquid discharge head In such a configuration, a control signal for image formation is sent from a control circuit (not shown) to drive IC 15 via FPC 18, input terminals 11a, 12a, 13 and the like. By inputting and controlling the operation of the drive IC 15, the drive IC 15 expands and contracts the piezoelectric element 8 based on the image signal to vibrate the diaphragm 7. As the diaphragm 7 vibrates, ink is supplied from an unillustrated main tank (ink cartridge) to the first and second common liquid chambers 17a and 17b via the supply ports 16a and 16b. At this time, the image forming liquid in the first and second common liquid chambers 17 a and 17 b is supplied to one end in the longitudinal direction of each liquid chamber 2 through the individual flow path 3 and the individual communication path 4.

  Along with this, liquid such as ink in the plurality of liquid chambers 2 is ejected from a plurality of nozzles 6 positioned on the opposite side of the individual communication passages 4 of the liquid chambers 2 to generate image signals on a recording medium (not shown). Forming a based image. Since the plurality of nozzles 6 of the first nozzle row Nz1 and the plurality of nozzles 6 of the second nozzle row Nz2 are close to each other, the plurality of nozzles 6 of the first nozzle row Nz1 and the second nozzle row Nz2 High density image formation control can be performed by individually controlling the plurality of nozzles 6.

  FIG. 8 is a cross-sectional view of Example 2 in which a reinforcing plate is attached between the nozzle plate and the actuator substrate.

  In this embodiment, an intermediate member (intermediate plate) 22 is pasted on the nozzle plate 5, the actuator substrate 1 is pasted on the intermediate member 22, and the nozzle plate 5 and the intermediate member are made small in order to reduce the input terminal connection portion. The end of 22 is extended (extended) outside the actuator substrate 1 so as to protrude from the actuator substrate 1, and the FPC 18 is pasted on the extended portion, and the FPC terminal (wiring terminal 19) and the actuator substrate 1 are attached. The upper electrodes (input terminals 11a, 12a, 13 etc.) are connected by wire bonding.

  By adopting this configuration, it is possible to greatly reduce the input terminal mounting area that becomes a blank portion for the ink jet head, and the actuator substrate 1 can be downsized.

  Here, the intermediate member 22 to be attached between the actuator substrate 1 and the nozzle plate 5 is formed to have the same size as the nozzle plate 5, and a communication hole 22 a larger than the nozzle diameter is provided at the position of the nozzle 6. Even when the thin nozzle plate 5 is used, the liquid chamber compliance can be reduced and the rigidity of the affixed portion of the FPC 18 is also improved, so that the reliability of the wire bonding portion can be improved.

  The backing plate 20 is affixed as a configuration of the affixing portion of the FPC 18. The backing plate 20 can increase the rigidity of the affixed portion of the FPC 18 and improve the reliability of the wire bonding connection portion for handling and the like.

  9 to 14 show the third embodiment. The basic configuration of the third embodiment is the same as that of the first embodiment. Here, the direction in which the first nozzle row Nz1 extends (nozzle arrangement direction of the first nozzle row Nz1) and the direction in which the second nozzle row Nz2 extends (nozzle arrangement direction of the second nozzle row Nz2) are hereinafter simply referred to as the nozzle arrangement direction. That's it. When the first piezoelectric element array Pz1 and the second piezoelectric element array Pz2 are used as a reference, the extending direction of the first piezoelectric element array Pz1 (piezoelectric element arrangement direction of the first piezoelectric element array Pz1), the second piezoelectric element array The direction in which Pz2 extends (the piezoelectric element arrangement direction of the second piezoelectric element array Pz2) can also be simply referred to as the piezoelectric element arrangement direction. Since the nozzle arrangement direction and the piezoelectric element arrangement direction indicate the same direction, the nozzle arrangement direction will be described below.

  In the third embodiment, terminals such as input terminals 11a, 12a, 13 are provided at both ends of the diaphragm 7 in the nozzle arrangement direction, and FPCs 18, 18 are provided at both ends of the diaphragm 7 in the nozzle arrangement direction. Are arranged respectively.

  The FPCs 18 and 18 are wire-bonded to the terminals such as the input terminals 11a, 12a, and 13 at both ends of the diaphragm 7 in the nozzle arrangement direction as in the first embodiment.

  Here, the first Com wiring 9 and the Vcom wiring 11 which are common wirings through which charging / discharging current flows to the plurality of piezoelectric elements 8 of the first piezoelectric element array Pz1, and the plurality of piezoelectric elements 8 of the second piezoelectric element array Pz2 are connected. The second Com wiring 10 and the Vcom wiring 12, which are common wirings through which the charge / discharge current flows, can be drawn out on both sides of the diaphragm 7 in the nozzle arrangement direction.

  According to the configuration of the third embodiment, even in a long head in which the number of nozzles / nozzle row increases, the in-row ejection characteristic variation due to the voltage waveform deterioration due to the common wiring resistance on the actuator substrate 1 can be suppressed.

  Therefore, the resistance of the common wiring (Vcom wirings 11 and 12, first and second Com wirings 9 and 10) on the actuator substrate 1 can be increased, and the wiring width can be reduced. In addition, the head width can be reduced, and the head can be miniaturized.

  FIGS. 15A and 15B show Embodiment 5 of the high-density liquid ejection head of the present invention. In the fifth embodiment, the thickness of the backing plate 20 of the FPC 18 described in the first embodiment is made thicker than that of the actuator substrate 1. Therefore, in Example 5, as shown in FIG. 15A, even if a resin plate having a lower elastic modulus than that of the actuator substrate is used, sufficient rigidity can be ensured and the adhesive protrudes. The adhesive on the electrode surface of the FPC 18 can be prevented from protruding.

  The end face of the backing plate 20 is abutted against the end face of the actuator substrate 1 and the abutting portion of the backing plate 20 and the actuator substrate 1 is adhered by the FPC adhesive 23, so that the thin portion is eliminated and the bending stress is prevented. Thus, stress on wire bonding can be reduced and connection reliability can be improved.

  By making the thickness of the backing plate 20 thicker than the thickness of the actuator substrate 1, the side surface of the backing plate 20 is abutted against the actuator substrate 1 and bonded together including the abutting surface, whereby the actuator substrate 1 and the FPC 18 are bonded. Bending at discontinuous portions can be prevented and connection reliability can be improved.

  Further, by adhering to the abutting portion, it is possible to adhere even to the side portion of the backing plate 20, and the continuity from the actuator substrate 1 to the adhesive portion of the FPC 18 can be secured, so that the rigidity is greatly improved and the connection reliability can be increased. .

  In FIG. 15A, the basic configuration of the high-density liquid discharge head is the same as that of the first embodiment. Wiring (Vcom wirings 11 and 12, first and second Com wirings 9 and 10) on the actuator substrate 1 and electrodes such as electrodes (not shown) and input terminals (11a, 12a and 13) of the diaphragm 7 are generally used. It is formed of a film mainly composed of aluminum used in a simple silicon process. Specifically, the structure is aluminum / silicon, aluminum / silicon / copper, or the like.

  The electrode film thickness is set to 2 μm to 4 μm. By increasing the film thickness, the wiring resistance can be reduced. However, if the film thickness is too large, it is difficult to ensure the coverage of the passivation film necessary to ensure wiring reliability. In order to achieve this, it is necessary to increase the etching aspect ratio of wiring formation and to narrow the wiring pitch, which becomes more difficult.

  For this reason, as a result of film thickness evaluation, the reliability of fine wiring could not be ensured at a film thickness exceeding 4 μm.

  On the other hand, it has been found that there is a restriction not only on the wiring resistance design but also on improving the bonding property for reducing the film thickness.

The following two points can be cited as measures for shortening the length of the electrodes (input terminals 11a, 12a, 13).
<First point>
One way to shorten the electrode length on the actuator substrate 1 side is to perform 2nd bonding of wires. This is because the 2nd bonding side of the bonding wire 21 is brought to the actuator substrate 1 side, that is, the electrodes (input terminals 11a, 12a, and 13) side, and the reverse operation during bonding becomes the FPC 18 side. To be able to do that.

  Here, it was found that when the actuator substrate 1 side is subjected to 2nd bonding, the actuator substrate goes through a high-temperature process, so that an oxide film on the surface of the aluminum electrode grows and bonding properties are deteriorated.

However, it has been found that by increasing the electrode thickness to 2 μm or more, the surface oxide film is easily broken, and stable bonding properties can be secured even for 2nd bonding.
<Second point>
Further, the electrodes (input terminals 11a, 12a, 13) are not extended to the edge of the actuator substrate 1. In addition, when the FPC 18 with the backing plate is abutted against the actuator substrate 1 and fixed by adhesion, the end surface of the actuator substrate 1 is also bonded to improve the rigidity of the bonded portion.

  At this time, the FPC adhesive 23 protrudes onto the actuator substrate 1, but by setting the electrode thickness to 2 μm or more, it is possible to suppress the adhesive from creeping up to the electrode surface to be wire bonded. Bondability can be ensured.

  FIG. 16A to FIG. 16C show the fifth embodiment. Also in the sixth embodiment, the basic head configuration is the same as that of the first embodiment.

  A charge / discharge current to the piezoelectric element flows through the common wiring of the actuator substrate 1 (Vcom wirings 11 and 12 and first and second Com wirings 9 and 10 in FIG. 6 of the first embodiment). When ink is simultaneously ejected from the plurality of nozzles 6 of the first and second nozzle rows Nz1 and Nz2, the Vcom wirings 11 and 12, the first and second Com wirings 9 in FIG. A large current flows through 10 instantly.

  For this reason, in connecting the FPC 18 of the first and second Com wires 9 and 10 and the Vcom wires 11 and 12 which are common wires in FIG. 6 of the first embodiment, the fusing of the bonding wires or the heat generation of the bonding wires is suppressed. It is necessary to bond the terminals of the input terminals 9a, 10a, 11a, 12a, 1 and the wiring terminals 19 of the FPC 18 in FIG. 6 of Example 1 with a plurality of bonding wires.

  In the fifth embodiment, as shown in FIG. 16A, the terminals such as the input terminals 9a, 10a, 11a, and 12a and the wiring terminal 19 of the FPC 18 are bonded together by two bonding wires 24 and 25. .

  When bonding a plurality of bonding wires 24 and 25, if the bonding wires 24 and 25 are widened in the bonding pitch direction, the width of the actuator substrate 1 and the width of the FPC 18 are widened due to bonding pitch restrictions, resulting in high costs.

  As a method of bonding while the width of the actuator substrate 1 is ensured to be narrow, bonding in a staggered arrangement is generally used, but it becomes necessary to increase the electrode length of the actuator substrate 1.

  Here, what is required is a plurality of bonding wires 24, 25 without increasing the width of the actuator substrate 1 and without increasing the length (electrode length) of the terminals (electrodes) such as the input terminals 9a, 10a, 11a, 12a. Are required to be bonded.

  In this embodiment, a plurality of bonding wires 24 and 25 are bonded in multiple stages on the same line. That is, the shorter bonding wire 24 is first bonded to the terminals (electrodes) such as the input terminals 9a, 10a, 11a, and 12a and the wiring terminal 19 of the FPC 18, and then the longer bonding wire 25 is connected to the input terminals 9a, Bonding is performed to terminals (electrodes) 10a, 11a, 12a and the like and wiring terminals 19 of the FPC 18. At this time, the bonding wires 24 and 25 are curved with a space therebetween in the vertical direction as shown in FIG. 16A and overlap as shown in FIGS. 16B and 16C. It is arranged like this.

  Further, the bonding wires 24 and 25 have the first bonding on the FPC 18 side, and the first-stage bonding wire 24 is bonded at a position where it does not contact the second-stage bonding wire 25.

  Further, the bonding wires 24 and 25 have 2nd bonding on the side of the actuator substrate 1, and bonding marks (a portion indicated by a wavy line in FIG. 16 (c)) 24a and bonding at the second stage are bonded by a capillary or the like when bonding the first stage bonding wire 24. Bonding is performed in a state where a bonding mark (a portion indicated by a wavy line in FIG. 16C) 25a at the time of bonding of the wire 25 overlaps.

  In this configuration, the electrode film is formed thick, and it has been found that good bonding quality can be ensured even when bonding marks overlap.

  17 and 18 show the sixth embodiment. The sixth embodiment shows an example in which the high-density liquid ejection head (inkjet head) of the first to fifth embodiments is applied to an image forming apparatus.

  In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown), and a driving pulley 106A is driven by a main scanning motor 104. And the driven pulley 106B are moved and scanned in the direction indicated by the arrow (main scanning direction) via the timing belt 105.

  For example, a recording head 107 for forming a color image is held on the carriage 103. The recording head 107 includes a high-density liquid ejection head 107k that ejects droplets (ink droplets) of black (K) recording liquid (ink), and a color droplet of cyan (C) color recording liquid (ink). High-density liquid ejection head 107c that ejects (ink droplets), high-density liquid ejection head 107m that ejects droplets (ink droplets) of magenta (M) color recording liquid (ink), and yellow (Y) color A high-density liquid ejection head 107y that ejects droplets (ink droplets) of recording liquid (ink) is provided. Any of the configurations of the high-density liquid ejection heads of Examples 1 to 5 is used for the high-density liquid ejection heads 107k, 107c, 107m, and 107y.

  Further, the high-density liquid ejection heads 107k, 107c, 107m, and 107y are arranged in a direction along the main scanning direction, and are mounted with the droplet ejection direction facing downward. In addition, although the independent high-density liquid discharge head is used here, it is also possible to employ a configuration in which one or a plurality of heads having a plurality of nozzle rows that discharge the recording liquid droplets of each color are used. Further, the number of colors and the arrangement order are not limited to this.

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

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

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

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

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

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

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

  Further, as shown in FIG. 18, a maintenance / recovery mechanism 156 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in the non-printing area on one side of the carriage 103 in the scanning direction.

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

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

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

Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103 in the forward and backward directions, ink droplets are ejected onto the stopped paper 112 to record one line, and the paper 112 is After transporting a predetermined amount, the next line is recorded.
Recording end signal or paper 1
Upon receiving a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is terminated, and the paper 112 is discharged onto the paper discharge tray 154.

In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 112 is fed into the double-sided paper feeding unit 155 by rotating the conveyor belt 121 in the reverse direction. The paper 112 is reversed (with the back surface being the printing surface), and is fed again between the counter roller 122 and the conveyor belt 121. The timing is controlled, and the sheet is conveyed onto the conveyor bell 121 as described above. Then, after recording on the back surface, the paper is discharged to the paper discharge tray 154. Also, during printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 156 side, and the nozzle surface of the recording head 107 is moved by the cap 157. Capping is performed to prevent ejection failure due to ink drying by keeping the nozzle in a wet state. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped by the cap 157 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 158 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

As described above, since the image forming apparatus includes the recording head constituted by the high-density liquid ejection head according to the present invention, it is possible to reduce the size and cost and to increase the number of ejectable nozzles with the same ejection head size. Therefore, further high-speed printing is possible. In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. Further, the present invention can be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.
(Supplementary explanation 1)
As described above, the high-density liquid ejection head according to the embodiment of the present invention includes the actuator substrate 1 on which a plurality of liquid chambers 2 are formed and the one side of the actuator substrate 1 that is provided on the one surface side of the actuator chamber 1. A nozzle plate 5 provided with a plurality of nozzles 6 for closing one end and discharging the liquid in the plurality of liquid chambers 2 respectively, and the other end of the liquid chamber 2 fixed to the other surface of the actuator substrate 1 A plurality of thin film-like diaphragms 7 that generate pressures that are respectively provided on the diaphragm 7 corresponding to the liquid chambers 2 and pressurize the liquid in the liquid chambers 2. A control device that drives and controls the piezoelectric element (piezoelectric element 8) and the plurality of thin film piezoelectric elements (piezoelectric element 8) via input terminals (9a, 10a, 11a, 12a, 13) provided on the diaphragm 7. (Drive IC15) and front Input terminals are provided (11a, 12a, 13a) the flexible wiring board for wiring connections to be connected to the (FPC 18). In addition, the nozzle plate 5 has an extending portion 5 a in which the edge portion on which the input terminals (9 a, 10 a, 11 a, 12 a, 13) of the diaphragm 7 are provided is formed larger than the actuator substrate 1. Also, a wiring end 18a provided with the wiring terminal 19 of the flexible wiring board (FPC 18) is fixed on the extending portion 5a, and the control device (driving IC 15) and the thin film piezoelectric element (piezoelectric element 8). The input terminals (9a, 10a, 11a, 12a, 13) and the wiring terminals 19 of the flexible wiring board (FPC 18) are connected by the wire bonding.

  According to this configuration, the input terminal (9a, 10a, 11a, 12a, 13) of the piezoelectric element or the drive IC 15 and the flexible wiring board (FPC 18) can be connected by wire bonding without a high step, and the actuator substrate 1 Can be reduced in size and cost.

As described above, in the high-density liquid ejection head in which the piezoelectric element 8 and the driving IC 15 are mounted on the actuator substrate 1, the FPC 18 connected to the head input terminals (9 a, 10 a, 11 a, 12 a, 13) is disposed outside the actuator substrate 1. Thus, the size of the actuator substrate 1 can be reduced by sticking on the nozzle plate 5 and connecting by wire bonding, the number of removal from the Si wafer or the like can be increased, and the cost of the head can be reduced. The corresponding ones of the liquid chamber 2, the nozzle 6 and the thin film piezoelectric element (piezoelectric element 8) form a liquid discharge portion, and a plurality of the liquid discharge portions are arranged in a straight line. In addition, the control device (drive IC 15) is mounted on the vibration plate 7 so as to be positioned on a portion of the vibration plate 7 where the plurality of liquid chambers 2 are not provided, and the control device (drive IC 15) and the thin film piezoelectric element are mounted. The input terminals (9a, 10a, 11a, 12a, 13a) of the (piezoelectric element 8) are formed at the edge of the diaphragm 7 so as to be positioned at the end of the liquid discharge unit in the arrangement direction.
(Supplementary explanation 2)
In the high-density liquid ejection head according to the embodiment of the present invention, an intermediate plate (intermediate member 22) is interposed between the nozzle plate 5 and the actuator substrate 1, and the intermediate plate (intermediate member). 22) is provided with an attachment end portion that extends to above the extension portion 5a of the nozzle plate 5, and the wiring end portion 18a of the flexible wiring board (FPC 18) is connected to the extension portion via the attachment end portion. It is fixed on 5a.

Thus, the intermediate plate (intermediate member 22) is provided between the nozzle plate 5 and the actuator substrate 1, and the FPC 18 connected to the input terminals (9a, 10a, 11a, 12a, 13) of the head is arranged outside the actuator substrate 1. Since the rigidity of the FPC pasting portion can be improved by sticking on the intermediate plate (intermediate member 22) and connecting by wire bonding, the reliability of the joint portion can be improved. Further, the intermediate plate (intermediate member 22) can also have the function of a communication pipe, and the compliance can be reduced even if the nozzle plate 5 is made thin, so that the output characteristics can be improved.
(Supplementary explanation 3)
In the high-density liquid discharge head according to the embodiment of the present invention, the extending portions 5a are provided on both ends in the arrangement direction of the plurality of liquid discharge portions, and the flexible wiring board (FPC18) is provided on both ends. ) And a wiring end 18a of each flexible wiring board (FPC 18) is fixed to each extending portion 5a.

According to this configuration, since the input terminals (9a, 10a, 11a, 12a, 13) are provided on both sides of the head, the common electrode wiring pattern on the actuator substrate 1 can be used while maintaining the miniaturization of the actuator substrate 1. The flowing current can be divided into two. Thereby, it is possible to suppress variation in characteristics within the row even when the head length is increased (the number of nozzles / row is increased).
(Supplementary explanation 4)
In the high-density liquid discharge head according to the embodiment of the present invention, the wiring end portion 18a of the flexible wiring board (FPC 18) is fixed on the extending portion 5a via a backing plate 20 attached to the back surface. Has been.

According to this configuration, the nozzle plate 5 is bonded with the backing plate 20 attached to the back surface of the FPC, so that the wire bonding portion can be protected against bending stress by increasing the rigidity of the bonding portion. Stress can be reduced and connection reliability can be improved.
(Supplementary explanation 5)
In the high-density liquid ejection head according to the embodiment of the present invention, the backing plate 20 is formed thicker than the actuator substrate 1.

According to this configuration, since the thickness of the backing plate 20 of the FPC 18 is thicker than that of the actuator substrate 1, sufficient rigidity can be ensured even if a resin plate having a lower elastic modulus than the actuator substrate 1 is used. In addition, even if the adhesive protrudes, it is possible to prevent the adhesive from protruding onto the surface of the FPC electrode.
(Supplementary explanation 6)
In the high-density liquid ejection head according to the embodiment of the present invention, the backing plate 20 is abutted against and bonded to the actuator substrate 1.

According to this configuration, since the actuator substrate 1 is abutted and bonded, there is no thin portion, stress against wire bonding can be reduced against bending stress and the like, and connection reliability can be improved.
(Supplementary explanation 7)
In the high-density liquid discharge head according to the embodiment of the present invention, the abutting surface of the backing plate 20 against the actuator substrate 1 is bonded to the actuator substrate 1.

According to this configuration, by bonding the backing plate 20 to the abutting portion to the actuator substrate 1, it is possible to bond at the side surface portion of the backing plate 20, so that continuity is also achieved at the bonded portion of the actuator substrate 1 and the FPC 18. Can be ensured, the rigidity is greatly improved, and the connection reliability can be increased.
(Supplementary explanation 8)
In the high-density liquid discharge head according to the embodiment of the present invention, the actuator substrate 1 side is the 2nd bonding side of wire bonding.

According to this configuration, since the actuator substrate 1 side is set to the 2nd bonding side of wire bonding, it is not necessary to secure a reverse operation region at the time of wire bonding. The input terminal length (9a, 10a, 11a, 12a, 13) of the actuator substrate 1 can be shortened. For this reason, the actuator substrate 1 can be made small.
(Supplementary explanation 9)
In the high-density liquid ejection head according to the embodiment of the present invention, the input terminal (9a, 10a, 11a, 12a, 13) on the actuator substrate 1 side is formed with aluminum as a main component and a film thickness of 2 μm to 4 μm. Has been.

According to this configuration, since the electrode on the actuator substrate 1 side is formed with aluminum as a main component and with a film thickness of 2 μm to 4 μm, the actuator substrate 1 is exposed to a high temperature process and an oxide film grows well. 2nd bonding quality can be ensured and the wiring pitch can be reduced.
(Supplementary explanation 10)
In the high-density liquid discharge head according to the embodiment of the present invention, the electrode terminals (input terminals 9a, 10a, 11a, 12a, 13) on the actuator substrate 1 are not extended to the edge of the actuator substrate 1. .

According to this configuration, since the electrode terminals on the actuator substrate 1, that is, the electrodes (input terminals 9a, 10a, 11a, 12a, and 13a) are not extended to the substrate edge, the adhesive in the bonding process of the FPC 18 has a protrusion. However, the protrusion to the electrode (input terminals 9a, 10a, 11a, 12a, 13a) surface of the actuator substrate 1 can be suppressed, and the wire bonding property is not deteriorated.
(Supplementary explanation 11)
In the high-density liquid ejection head according to the embodiment of the present invention, Vcom and Com terminals (input terminals 9a, 10a, 11a, and 12a) through which current flows when charging and discharging the thin film piezoelectric element (piezoelectric element 8) are as follows. Wire bonding is performed in multiple stages on the same line.

In this configuration, Vcom and Com terminals (input terminals 9a, 10a, 11a, and 12a) through which current flows when charging / discharging the thin film piezoelectric element on the actuator substrate flow a large current, and thus it is necessary to bond a plurality of wires. . Here, since wire bonding is performed in multiple stages on the same line, the bonding width can be suppressed, and the actuator substrate width and the FPC width can be reduced.
(Supplementary explanation 12)
Further, in the high-density liquid discharge head according to the embodiment of the present invention, the actuator substrate 1 side is the 2nd bonding side of wire bonding, and bonding marks for multi-stage bonding overlap.

According to this configuration, when the 2nd bonding is performed on the same line in multiple stages at the terminal where the charging / discharging current of the actuator substrate 1 flows, the bonding traces are overlapped, so that the electrode length of the actuator substrate can be shortened. .
(Supplementary explanation 13)
The image forming apparatus according to the embodiment of the present invention is equipped with the above-described high-density liquid ejection head.

  According to this configuration, a low-cost image forming apparatus can be realized by mounting a high-density liquid ejection head that enables downsizing of the actuator substrate 1.

DESCRIPTION OF SYMBOLS 1 Actuator board | substrate 1a Side edge part 1b Side edge part 2 Liquid chamber Lq1 1st liquid chamber row | line | column Lq2 2nd liquid chamber row | line | column 3 Individual flow path 4 Individual communication path 5 Nozzle plate 5a Extension part (protruding end part)
6 nozzles Nz1 first nozzle row Nz2 second nozzle row 7 diaphragm (thin film diaphragm)
7a Side edge 7b Side edge 7c End 7P Communication path 8 Piezoelectric element (thin film piezoelectric element)
Pz1 First piezoelectric element array Pz2 Second piezoelectric element array 9 First Com wiring (first Com pattern wiring)
9a Input terminal (electrode)
10 Second Com wiring (second Com pattern wiring)
10a Input terminal (electrode)
11 Vcom wiring (Vcom pattern wiring)
11a Input terminal (electrode)
12 Vcom wiring (Vcom pattern wiring)
12a Input terminal (electrode)
13 Input terminal (electrode)
14 Lower frame plate (subframe)
14a Vibration allowable recess 14b Installation space 15 Drive IC (control device)
16 Upper frame plate (upper frame)
16a supply port 16b supply port 17a first common liquid chamber 17b second common liquid chamber 18 FPC (flexible wiring board)
18a Wiring end 19 Wiring terminal 20 Backing plate 21 Bonding wire 22 Intermediate member (intermediate plate)
22a Communicating hole 23 Adhesive for FPC 24 Bonding wire 24a Bonding mark 25 Bonding wire 25a Bonding mark

JP 2011-110743 A JP 2009-255444 A

Claims (13)

An actuator substrate formed with a plurality of liquid chambers;
A nozzle plate provided on one side of the actuator substrate and provided with a plurality of nozzles for closing one end of the liquid chamber and discharging the liquid in the plurality of liquid chambers;
A thin-film diaphragm fixed to the other surface of the actuator substrate and closing the other end of the liquid chamber;
A plurality of thin film piezoelectric elements respectively provided on the diaphragm corresponding to the liquid chambers and generating pressures for pressurizing the liquids in the liquid chambers;
A control device that drives and controls the plurality of thin film piezoelectric elements via an input terminal provided on the diaphragm;
A high-density liquid ejection head comprising a flexible wiring substrate for wiring connection connected to the input terminal,
The nozzle plate has an extending portion in which the edge side where the input terminal of the diaphragm is provided is formed larger than the actuator substrate,
The wiring end portion provided with the wiring terminal of the flexible wiring board is fixed on the extending portion, and the input terminal of the control device and the thin film piezoelectric element and the wiring terminal of the flexible wiring board are connected by the wire bonding. A high-density liquid discharge head characterized by being made.   2. The high-density liquid discharge head according to claim 1, wherein an intermediate plate is interposed between the nozzle plate and the actuator substrate, and the intermediate plate extends to the extension portion of the nozzle plate. A high-density liquid ejection head, comprising: a mounting end portion, wherein the wiring end portion of the flexible wiring board is fixed on the extension portion via the mounting end portion.   3. The high-density liquid ejection head according to claim 1, wherein the extending portions are respectively provided on both end sides in the arrangement direction of the plurality of liquid ejection portions, and the flexible wiring board is provided on both end sides. And a wiring end portion of each of the flexible wiring boards is fixed to each of the extending portions.   The high-density liquid discharge head according to claim 2 or 3, wherein the wiring end portion of the flexible wiring board is fixed on the extended portion via a backing plate attached to the back surface. High density liquid discharge head.   5. The high-density liquid ejection head according to claim 4, wherein the backing plate is thicker than the actuator substrate.   5. The high-density liquid discharge head according to claim 4, wherein the backing plate is abutted against and bonded to the actuator substrate.   The high-density liquid discharge head according to claim 6, wherein an abutting surface of the backing plate to the actuator substrate is bonded to the actuator substrate.   8. The high-density liquid discharge head according to claim 1, wherein the actuator substrate side is a 2nd bonding side of wire bonding.   9. The high-density liquid ejection head according to claim 1, wherein the input terminal on the actuator substrate side is an electrode terminal formed of aluminum as a main component and having a film thickness of 2 μm to 4 μm. A high-density liquid discharge head characterized by   10. The high density liquid discharge head according to claim 1, wherein the electrode terminal on the actuator substrate is not extended to an edge of the actuator substrate. 11.   11. The high-density liquid ejection head according to claim 1, wherein Vcom and Com terminals through which a current flows when charging and discharging the thin film piezoelectric element are wire-bonded in multiple stages on the same line. A high-density liquid discharge head that is characterized.   The high-density liquid discharge head according to claim 10, wherein the actuator substrate side is a 2nd bonding side of wire bonding, and bonding marks for multi-stage bonding are overlapped.   An image forming apparatus comprising the high-density liquid ejection head according to claim 1.