Patent Publication Number: US-7896471-B2

Title: Recording head and methods for manufacturing and inspecting the recording head

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2006-282937, which was filed on Oct. 17, 2006, the disclosure of which is herein incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to a recording head, and more particularly to a recording head configured such that external signals are inputted thereto using a flexible wiring member, and to methods for manufacturing and inspecting the recording head. 
     2. Discussion of Related Art 
     As a recording apparatus configured to perform recording by ejection of ink from a recording head onto a recording medium, there has been known a recording apparatus disclosed in a Patent Document 1 (JP-A-2002-160372, in particular, FIGS. 4 and 6). In the disclosed recording apparatus, an external signal source and the recording head are connected to each other by a flexible wiring member on which is mounted a drive circuit, and signals supplied from the external signal source are inputted to the recording head via a drive circuit, so that the ink is ejected selectively from nozzles of the recording head, thereby performing the recording. 
     In a case where an actuator included in the recording head is, for example, a piezoelectric actuator as disclosed in the Patent Document 1, etc., voltage for polarizing may be applied to the piezoelectric actuator using the flexible wiring member after the flexible wiring member is connected to the piezoelectric actuator, thereby polarizing portions of a piezoelectric layer of the piezoelectric actuator which are to function as operable portions. 
     More specifically described, there are provided a shift register, a D flip-flop, a driver, etc., in the drive circuit mounted on the flexible wiring member disclosed in the Patent Document 1. The flexible wiring member includes conductor wires (i.e., lines) VDD 1 , VSS 1 , VDD 2 , VSS 2  that are connected to the drive circuit. The conductor wires (i.e., lines) VSS 1 , VSS 2  are connected to a common voltage portion of the drive circuit, and are normally grounded. Further, the flexible wiring member includes a conductor wire (i.e., line) VSS 3  which is commonly connected to a common electrode (a common voltage portion) of one of piezoelectric deformable portions (each as the operable portion). 
     When polarizing, in a manufacturing process, the piezoelectric actuator of the recording head which has been assembled, a device constituted by a circuit and a power source (that are equivalent of a circuit and a power source that are used for ejecting the ink) is connected to the conductor wires VDD 1 , VSS 1 , VDD 2 , VSS 2 , etc., of the flexible wiring member, and a polarizing device is connected to the conductor wire VSS 3 . Then, voltage of V 1  is applied from the conductor wire VDD 2  to the operable portions of the actuator via the drive circuit, and in addition, minus voltage V 2  is applied to the conductor wire VSS 3 , so that total voltage of (V 1 +V 2 ) is applied to the operable portions, thereby polarizing the piezoelectric actuator. When the ink ejection is performed after the polarization has been completed, the conductor wires VSS 2 , VSS 3  are connected to each other via another conductor wire so as to be kept at almost the same voltage with each other, e.g., at zero voltage or a ground. 
     In a case where the flexible wiring member is connected to the piezoelectric actuator by soldering after the piezoelectric actuator has been polarized, a polarized condition of the piezoelectric actuator may be deteriorated due to a heat generated by the soldering. However, in the recording apparatus disclosed in the Patent Document 1, the polarization is performed after the flexible wiring member has been connected to the recording head, thereby maintaining a good polarized condition of the piezoelectric actuator. 
     SUMMARY OF THE INVENTION 
     There may be a need to inspect the recording head that is ready for ejecting the ink after completion of the polarization, for example, by measuring an electrostatic capacity of the piezoelectric actuator and a value of resistance between the respective operable portions. In this instance, if the conductor wire VDD 2  connected to the common voltage portion of the drive circuit and the conductor wire VDD 3  connected to the common voltage portion of the actuator that is common to the operable portions are joined to each other, a characteristic of the piezoelectric actuator could not be reliably detected because an electrical current via the drive circuit is measured in the detection. 
     A problem similar to the above-described problem is also occurred in a different-type recording head having a drive circuit. In this recording head, a characteristic of each of a plurality of operable portions could not be reliably detected, either. 
     The present invention has been developed in view of the background discussed above. It is therefore an object of the present invention to provide a recording head in which a characteristic thereof can be reliably and finely detected, and to provide methods for manufacturing and inspecting the recording head. 
     A recording head according to a first aspect of the present invention includes: an actuator including a plurality of operable portions operable to cause the recording head to perform a recording; a drive circuit configured to drive the plurality of operable portions of the actuator; a wiring member on which the drive circuit is mounted, which is joined to the actuator, and which has a plurality of conductor wires including a first common voltage wire connected to a common voltage portion of the actuator that is common to the plurality of operable portions and a second common voltage wire connected to a common voltage portion of the drive circuit. The recording head according to the first aspect of the present invention further includes: one of (A) a conductor configured to establish, in an outer surface of the wiring member, an electrical conduction or connection between the first common voltage wire and the second common voltage wire; and (B) conducting means configured to establish, in the outer surface of the wiring member, the electrical conduction between the first common voltage wire and the second common voltage wire. 
     Further, a method for inspecting the recording head in accordance with a second aspect of the present invention is applied to the recording head in which said one of the conductor and the conducting means is configured such that the electrical conduction between the first common voltage wire and the second common voltage wire is breakable, where necessary, the method including: breaking the electrical conduction between the first common voltage wire and the second common voltage wire established by said one of the conductor and the conducting means; detecting a characteristic of the actuator via the first common voltage wire after the electrical conduction is broken, so as to inspect the recording head; and establishing, by said one of the conductor and the conducting means, the electrical conduction between the first common voltage wire and the second common voltage wire in the wiring member after the characteristic of the actuator is detected. 
     Further, a method for manufacturing the recording head in accordance with a third aspect of the present invention includes: preparing the wiring member which is joined to the actuator and without the electrical conduction being established in the wiring member; polarizing the plurality of operable portions of the actuator by applying a voltage via the first common voltage wire for the wiring member which has been prepared; and establishing, by said one of the conductor and the conducting means, the electrical conduction between the first common voltage wire and the second common voltage wire in the wiring member after the polarization has been performed. 
     According to the present invention, in a state in which the first common voltage wire and the second common voltage wire is not connected to each other, the inspection can be performed without an influence of the drive circuit, or the polarization can be appropriately performed on the plurality of operable portions of the actuator. Then, after the inspection or the polarization is performed, the electrical conduction between the first common voltage wire and the second common voltage wire can be established in a convenient manner. Consequently, in a state in which the electrical conduction between the first common voltage wire and the second common voltage wire is established, recording can be appropriately performed by the recording head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and optional objects, features, and advantages of the present invention will be better understood by reading the following detailed description of preferred embodiments of the invention when considered in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a plan view showing an ink-jet recording apparatus equipped with a recording head as an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of a carriage holding the recording head; 
         FIG. 3  is a cross-sectional schematic view showing a cross section of the carriage, taken in a plane parallel to a Y direction; 
         FIG. 4  is an exploded perspective view of the recording head; 
         FIG. 5  is a perspective view schematically showing a portion of the recording head at which a first wiring member and a second wiring member thereof are joined to each other; 
         FIG. 6  is a perspective view schematically showing a portion of the second wiring member at which is joined to a connector; 
         FIG. 7A  is a cross sectional view showing a state in which the first and second common voltage wires of the second wiring member are not connected to a first and second conductive layers provided by the outer surface of the second wiring member; 
         FIG. 7B  is a cross sectional view showing a state in which the first common voltage wire is connected to the first conductive layer; 
         FIG. 7C  is a cross sectional view showing a state in which the second common voltage wire is connected to the second conductive layer; 
         FIG. 8A  is a plan view showing a first surface as one of opposite surfaces of a flexible wiring member constituted by the first and second wiring members; 
         FIG. 8B  is a plan view showing a second surface as the other of the opposite surfaces of the flexible wiring member; 
         FIG. 9A  is a side view showing the flexible wiring member, where a conductive tape is adopted as a conductor; 
         FIG. 9B  is a plan view showing the flexible wiring member, where a conductive clip is adopted as a conductor; 
         FIG. 9C through 9E  are explanatory views explaining how to fold the flexible wiring member, where folding of the flexible wiring member is adopted as conducting means; 
         FIG. 10  is a diagram showing an example of an electrical circuit applied to the ink-jet recording apparatus; and 
         FIG. 11  is a diagram showing an example of an electrical circuit which is used when a polarization is performed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, there will be described a preferred embodiment of the present invention by reference to the drawings.  FIG. 1  shows an ink-jet recording apparatus  100  having a recording head as an embodiment of the present invention. The ink-jet recording apparatus  100  is utilized, for instance, not only as an independent printer device, but also as a printer function of a Multi Function Device (MFD) with a copier function, a scanner function, a facsimile function, etc. Inside a body frame  2  of the ink-jet recording apparatus  100 , there is disposed a carriage  3  equipped with a recording head  1  which performs recording by ejection of ink onto a sheet PA as a recording medium. 
     In the body frame  2 , the carriage  3  is slidably held on or supported by a rear guide shaft  6  and a front guide shaft  7  which are disposed in parallel with each other so as to extend in a main scanning direction of the carriage  3 , i.e., in a Y direction shown in  FIG. 1 . The carriage  3  is configured to reciprocate in the main scanning direction, i.e., in the Y direction, by a carriage-driving motor  17  disposed at a right rear portion of the body frame  2  as seen in  FIG. 1  and a timing belt  18  as an endless belt. Inks are supplied from respective ink supply sources (i.e., ink tanks)  5   a ,  5   b ,  5   c ,  5   d  which are statically disposed in the body frame  2  toward the carriage  3  via respective ink supply tubes  14   a ,  14   b ,  14   c ,  14   d . In this ink-jet recording apparatus, there are respectively accommodated, in the respective ink tanks  5   a  through  5   d , inks of four colors, e.g., a yellow ink (Y), magenta ink (M), a cyan ink (C), and a black ink (Bk). 
     The sheet PA is horizontally fed by a known sheet-feeding mechanism (not shown) below a lower surface of the recording head  1  in a sub scanning direction (i.e., an X direction or a direction indicated by an arrow A shown in  FIG. 1 ) perpendicular to the main scanning direction or the Y direction. The inks are ejected downward onto the sheet PA from a plurality of nozzles (not shown) which are open in the lower surface of the recording head  1  that is moved in the main scanning direction or the Y direction, whereby the recording is performed. In the following description, a side or a surface of each component of the ink-jet recording apparatus  100  which is nearer to a side or a surface of the recording head  1  in which the nozzles are open (i.e., nozzle-opening surface or side of the recording head  1 ) is referred to as a front or lower side or a front or lower surface of each component, while a side or a surface of each component which is remote from the nozzle-opening surface or nozzle-opening side of the recording head  1  is referred to as a back or upper side or a back or upper surface of each component. 
     As shown in  FIGS. 2 and 3 , the carriage  3  includes a head holder  8  having a generally box-like shape which is open upward. On a lower side of a bottom plate  8   a  of the head holder  8 , a recessed portion  8   b  is formed so as to be open downward. The recording head  1  is fixedly accommodated in the recessed portion  8   b  such that the nozzles are exposed downward and such that the recording head  1  is kept in a posture substantially parallel to the bottom plate  8 . 
     On a back side of the head holder  8 , there is disposed a head-side circuit board  22  on which is formed an electrical circuit that is electrically connected to a body-side circuit board  90  disposed in the body frame  2 . The head-side circuit board  22  is connected to an external signal source via a flexible wiring member  99 . The body-side circuit board  90  and the flexible wiring member  99  are shown in  FIG. 10 . The head-side circuit board  22  is disposed at a position where the head-side circuit board  22  overlaps the recording head  1  in a plan view when viewed from the back side of the head holder  8 . 
     On an upper side of the bottom plate  8   a  of the head holder  8 , there is disposed, between the recording head  1  and the head-side circuit board  22 , a damper device  9  which stores the inks that have been supplied toward the carriage  3 . An inner space of the damper device  9  is divided into a plurality of ink chambers in which are respectively stored the inks of different colors that have been supplied via the respective ink supply tubes  14   a  through  14   d . The damper device  9  has: air-discharging valve means  9   b  which is for removing air bubbles remaining in the inks stored in the respective ink chambers; and ink outlets  9   a  through which the inks are supplied to the recording head  1 . An opening (not shown) is formed through the bottom plate  8   a  of the head holder  8 . As shown in  FIGS. 2 and 4 , inside the opening, the ink outlets  9   a  of the damper device  9  are connected to respective ink inlets  37  formed in the recording head  1  via respective connecting holes  15   b  formed in a reinforcing frame  15 , whereby the inks of the different colors are supplied independently of each other from the damper device  9  to the recording head  1 . 
     As shown in  FIGS. 2 and 3 , there is formed, through the bottom plate  8   a  of the head holder  8   a , a slit  55  through which a flexible wiring member  12  of the recording head  1  is inserted from a front side of the bottom plate  8   a  to a back side thereof. The flexible wiring member  12  passes through the slit  55 , extends upward along an inner surface of a side wall of the head holder  8 , and is connected to a connector  23  provided on the head-side circuit board  22 . The bottom plate  8   a  is further formed with through-holes  56  through which an adhesive agent is poured for fixing the recording head  1  to the front side of the bottom plate  8   a . Further, a later-described drive IC chip  12   a  is mounted on the flexible wiring member  12 . On the upper side of the bottom plate  8   a , there is disposed a radiator  50  which has a L-shape as seen in a side view and which is held in close contact with the drive IC chip  12   a . The drive IC chip  12   a  is biased by a rubber-like elastic member  51  via the flexible wiring member  12  toward the radiator  50 , whereby a heat generated in the drive IC chip  12   a  can be reliably radiated. The flexible wiring member  12  and the drive IC chip  12   a  will be explained in greater detail. 
     The recording head  1  has a laminar structure in which a cavity portion  10 , the piezoelectric actuator  11  and the flexible wiring member  12  are stacked on each other. The cavity portion  10  includes the plurality of nozzles which are open in its lower surface and ink channels which are formed therein. The piezoelectric actuator  11  applies an ejection pressure to the ink in the cavity portion  10 . The flexible wiring member  12  includes a drive circuit which outputs a drive signal for selectively driving the piezoelectric actuator  11 . Further, the reinforcing frame  15  is fixed on a back surface of the cavity portion  10 . 
     Like known cavity portions disclosed in JP-A-2001-246744 and JP-A-2005-313428, for instance, the cavity portion  10  is configured such that the inks individually supplied to the corresponding ink inlets  37  which are exposed on an upper surface of the cavity portion  10  at its one of opposite end portions in the X direction are distributed, through the corresponding manifold chambers (not shown) in the cavity portion  10 , into a plurality of pressure chambers (not shown). Operable portions of the piezoelectric actuator  11  are actuated to selectively apply the ejection pressure to the pressure chambers, whereby the inks are ejected from the nozzles communicating with the corresponding pressure chambers. 
     The piezoelectric actuator  11  in the present embodiment has a construction similar to that of a known actuator disclosed in JP-A-2005-322850, for instance. More specifically explained, the piezoelectric actuator  11  includes a plurality of ceramic layers which are stacked on each other in a direction perpendicular to planes thereof and inner electrodes (not shown) each sandwiched by and between adjacent two of the ceramic layers. In each of the ceramic layers, the operable portions are formed such that each active portion is located in an area of the ceramic layer vertically interposed between adjacent two of the inner electrodes. Described in detail, the inner electrodes include inner individual electrodes corresponding to the respective pressure chambers and inner common electrodes each common to the plurality of pressure chambers. Accordingly, one operable portion is formed in an area of each ceramic layer vertically interposed between one inner individual electrode and a corresponding portion of one inner common electrode. As shown in  FIG. 4 , there are formed, on an upper surface of the piezoelectric actuator  11 , external individual terminals  43  connected to the respective inner individual electrodes via respective electric through holes and an external common terminal  44  connected to the inner common electrodes. The operable portions are deformed by drive pulse signals applied to the corresponding external individual terminals  43  via the drive circuit, whereby the ejection pressure is selectively applied to the corresponding pressure chambers. The external individual terminals  43  and the external common terminal  44  are electrically connected to terminals (not shown) formed on the flexible wiring member  12 . 
     The reinforcing frame  15  is for reinforcing the cavity portion  10  and is a frame-like member made of a material having a higher degree of rigidity than the cavity portion  10 . For instance, the reinforcing frame  15  is provided by a metal plate formed of SUS. The reinforcing frame  15  has a size in its plan view somewhat larger than that of the cavity portion  10 . The reinforcing frame  15  is superposed on and fixedly bonded to the back surface of the cavity portion  10  so as to surround the piezoelectric actuator  11 , thus preventing deformation and distortion of the cavity portion  10  having a thin flat shape. 
     The flexible wiring member  12  is a flexible band-like cable for electrically connecting the above-described head-side circuit board  22  and the piezoelectric actuator  11  to each other. The flexible wiring member  12  is elongated in a direction in which a multiplicity of conductor wires formed thereon extend. The flexible wiring member  12  includes a first wiring member  121  and a second wiring member  122  which are arranged in a longitudinal direction of the flexible wiring member  12  and which are joined to each other. A back surface or a second surface of one of opposite end portions of the first wiring member  121  in a longitudinal direction thereof faces the piezoelectric actuator  11 . The drive IC chip  12   a  having a drive circuit for driving the piezoelectric actuator  11  is mounted on the first wiring member  121  in a portion thereof extending from a portion which faces the piezoelectric actuator  11 . One of the opposite end portions of the second wiring member  122  is joined to the first wiring member  121 . On the other of the opposite end portions of the second wiring member  122 , there is formed a terminal portion  12   b  which is connectable to the connector  23  of the head-side circuit board  22 . 
     The flexible wiring member  12  includes conductor wires, e.g., first common voltage wires  61  (i.e., a later-described conductor line VSS 3 ) each connected to the external common terminal  44  of the piezoelectric actuator  11 , second common voltage wires  62  (i.e., a later-described ground conductor line VSS 2 ) each connected to a common voltage portion of a later-described drive-voltage-signal generating circuit  97  of the drive IC-chip  12   a , signal wires  63  for inputting, into the drive IC-chip  12   a , various drive signals for recording, later-described conductor lines VDD 1 , VDD 2 , VSS 1 , and the like. 
     As shown in  FIG. 5 , the conductor wires including the first common voltage wires  61 , the second common voltage wires  62 , the signal wires  63  and the like are configured to extend in the longitudinal direction of the first and second wiring member  121 ,  122 . Each first common voltage wire  61  is divided by two parts, i.e., a part disposed in the first wiring member  121  and another part disposed in the second wiring member  122 , and these two parts are joined to each other at a joint portion  12   c  (see  FIG. 5 ). Also, each second common voltage wire  62  is divided by two parts in the same manner as the first common voltage wire  61 , and these two parts are joined to each other at the joint portion  12   c . These conductor wires are disposed in a following manner: the first common voltage wires  61  are disposed at respective positions nearer to outermost opposite side end portions of the flexible wiring member  12  in a widthwise direction thereof; the second common voltage wires  62  are disposed inside and adjacent to the respective first common voltage wires  61  so as to extend along the opposite side end portions of the flexible wiring member  12 ; other conductor wires such as the signal wires  63  are arranged inside and interposed between the second common voltage wires  62 . 
     The first wiring member  121  is configured by including band-like electrical insulating layer  40 , later-described terminals (not shown) and the plurality of conductor wires  61 ,  62 ,  63 . More specifically described, the electrical insulating layer  40  is made of a flexible synthetic resin material, e.g., a polyimide resin. On an upper surface of the electrical insulating layer  40 , there are formed, by a photolithography, the terminals and the plurality of conductor wires  61 ,  62 ,  63 . The terminals and the plurality of conductor wires  61 ,  62 ,  63  are covered by a cover lay (not shown) which is made of a synthetic resin material, e.g., the polyimide resin, and which has an electrical insulating properties and a flexibility. 
     Further, on the upper surface of the electrical insulating layer  40 , there is mounted the drive IC-chip  12   a  to which the conductor wires are connected. On a back surface of the first wiring member  121  which faces the piezoelectric actuator  11 , there are disposed the terminals (not shown) whose conductor wires are exposed at positions respectively corresponding to the external common terminal  44  and the external individual terminals  43  of the piezoelectric actuator  11 . The first common voltage wires  61  and the conductor wires extending from an outputting side of the drive IC-chip  12   a  are appropriately bent and routed up to the corresponding terminals. In an upper side of the joint portion  12   c  at which the first and second wiring member  121 ,  122  are joined to each other, the conductor wires are exposed. As the first wiring member  121 , there is employed a chip-on flexible flat cable (COF). 
     As shown in  FIG. 5 , the second wiring member  122  is a multi-purpose cable on which are formed, in parallel to each other at a constant pitch in a widthwise direction, a plurality of conductor wires ( 61 ,  62 ,  63 , etc.) that are vertically sandwiched by the band-like electrical insulating layers  40  made of the flexible synthetic resin material (e.g., the polyimide resin). Further, as the second wiring member  122 , there is employed a so-called shield flexible flat cable (shield FFC) in which the upper and lower electrical insulating layers  40  are respectively covered by conductive layers electrically independent of each other. On the upper and lower electrical insulating layers  40 , there are respectively superposed first and second conductive layers  41   a ,  41   b . The first and second conductive layers  41   a ,  41   b  are formed to include an aluminum foil and the like. Further, in the second wiring member  122 , there is provided a conductor  64  for establishing an electrical conduction between the first and second conductive layers  41   a ,  41   b . There will be more specifically described the conductor  64 . 
     In the first wiring member  121 , the conductor wires are provided in parallel to each other without overlapping in a plan view. However, in the second wiring member  122 , each pair of the first common voltage wires  61  are vertically superposed on each other in a thickness direction of the second wiring member  122 , and are held in contact so as to be electrically connected to each other. Further, in the second wiring member  122 , each pair of the second common voltage wires  62  are vertically superposed on each other in a thickness direction of the second wiring member  122 , and are held in contact so as to be electrically connected to each other. One of the first common voltage wires  61  which is provided in an upper side of the second wiring member  122  is referred to as an upper first common voltage wire  61   a , and the other of the first common voltage wires  61  which is provided in a lower side of the second wiring member  122  is referred to as a lower first common voltage wire  61   b . One of the second common voltage wires  62  which is provided in the upper side of the second wiring member  122  is referred to as an upper second common voltage wire  62   a , and the other of the second common voltage wires  62  which is provided in the lower side of the second wiring member  122  is referred to as a lower second common voltage wire  62   b.    
     As shown in  FIG. 5 , the first common voltage wires  61   a ,  61   b  are disposed in the above-described manner in which the two wires are vertically superposed on each other, at respective positions nearer to outermost opposite side end portions of the second wiring member  122  in a widthwise direction thereof. The second common voltage wires  62   a ,  62   b  are disposed inside and adjacent to the respective first common voltage wires  61   a ,  61   b , and are vertically superposed on each other as the first common voltage wires  61   a ,  61   b . Other conductor wires such as the signal wires  63  are disposed inside and interposed between the second common voltage wires  62   a ,  62   b , without the signal wires  63  being vertically superposed on each other 
     As shown in  FIG. 7A , in the second wiring member  122 , a first end  122   a  (as one of opposite end portions of the second wiring member  122 ) which is to be joined to the first wiring member  121  functions as a terminal in which the wires are exposed by removing the upper and lower electrical insulating layers  40 . It is noted that  FIG. 7  schematically shows a dimension of the second wiring member  122  in a thickness direction thereof. 
     As shown in  FIGS. 5 ,  7 B and  8 A, in a terminal portion of each of the first common voltage wires  61  which is exposed toward the joint portion  12   c , as one of the two wires vertically superposed on each other in the thickness direction, the upper first common voltage wire  61   a  provided in the upper side of the second wiring member  122  is exposed in the upper electrical insulating layers  40  and is bent so as to be overlapped with the first conductive layer  41   a , whereby the upper first common voltage wire  61   a  is electrically connected to the first conductive layer  41   a . As shown in  FIGS. 7C and 8B , in a terminal portion of each of the second common voltage wires  62  which is exposed toward the joint portion  12   c , as one of the two wires vertically superposed on each other in the thickness direction, the lower second common voltage wire  62   b  provided in the lower side of the second wiring member  122  is exposed in the lower electrical insulating layers  40  and is bent so as to be overlapped with the second conductive layer  41   b , whereby the lower second common voltage wire  62   b  is electrically connected to the second conductive layer  41   b.    
     As shown in  FIGS. 5 ,  8 A and  8 B, it is noted that the lower first common voltage wire  61   b  provided in the lower side of the second wiring member  122  is electrically connected, without the wire  61   b  being bent, to a corresponding one of the first common voltage wires  61  of the first wiring member  121 . The upper second common voltage wire  62   a  provided in the upper side is electrically connected, without the wire  62   a  being bent, to a corresponding one of the second common voltage wires  62  of the first wiring member  121 . Other conductor wires including the signal wires  63  are electrically connected to other respective conductor wires including the signal wires  63  of the first wiring member  121 . 
     As shown in  FIG. 6 , a second end  122   b  (as the other of opposite end portions of the second wiring member  122 ) which is to be joined to the connector  23  of the head-side circuit board  22  functions as a terminal in which the wires are exposed by removing only the lower electrical insulating layers  40 . As shown in  FIGS. 6 and 8B , in a terminal portion of each of the second common voltage wires  62  which is exposed in the other of opposite end portions of the second wiring member  122 , as one of the two wires vertically superposed on each other in the thickness direction, the lower second common voltage wire  62   b  provided in the lower side of the second wiring member  122  is bent so as to be overlapped with the second conductive layer  41   b , thereby being electrically connected thereto. The first common voltage wire  61 , the upper second common voltage wire  62   a  provided in the upper side and other respective conductor wires including the signal wires  63  are electrically connected, without them being bent, to respective terminals provided in the connector  23  so as to be connectable thereto and disconnectable therefrom. 
     A reinforcing member  122   b  is adhered to an upper surface of the second end  122   b  of the second wiring member  122 , thereby facilitating a handling of the second end  122   b  when the same  112   b  is to be connected to the connector  23 . The above-described portion (which is bent) of each of the upper and lower first common voltage wires  61   a ,  61   b  and the upper and lower second common voltage wire  62   a ,  62   b  provides as an exposed portion that is exposed in the outer surface of the wiring member  12 . 
     On the upper and lower surfaces of the second wiring member  122 , the first and second conductive layers  41   a ,  41   b  are electrically independent of each other. In the present embodiment, as the conductor  64  for establishing or breaking the electrical conduction between the first conductive layer  41   a  provided on the upper surface and the second conductive layer  41   b  provided on the lower surface, there is adopted a conductive tape  64   a  (i.e., a conductive member) which is stickable or removable, such as a copper-foil tape, an aluminum-foil tape and the like. As shown in  FIGS. 5 ,  8 A,  8 B and  9 A, the conductive tapes  64   a ,  64   a  are respectively stuck at the opposite side ends of the second wiring member  122  which are parallel to each other in the longitudinal direction of the second wiring member  122  so as to be provided over the first and second conductive layers  41   a ,  41   b . Since the conductive tape  64   a  is stickable on and removable from the second wiring member  122 , the electrical conduction can be easily and reliably established and broken between the first and second conductive layers  41   a ,  41   b  respectively provided on the upper and lower surfaces of the second wiring member  122 . When the first and second conductive layers  41   a ,  41   b  are electrically conducted to each other, the first common voltage wire  61  and the second common voltage wire  62  are electrically conducted to each other via the same layers  41   a ,  41   b  and the exposed portions. 
     The second common voltage wire  62  is provided to be grounded (e.g., to be connected to a ground). Therefore, when the first common voltage wire  61  and the second common voltage wire  62  are conducted to each other by conductor  64 , an electric potential of the first common voltage wire  61  becomes equal to the ground. In a case in which the conductive tape  64   a  is adopted as the conductor  64 , a widthwise dimension W of the conductive tape  64   a  ( FIG. 8A ) can be easily enlarged, or the first and second conductive layers  41   a ,  41   b  can be conducted, at a plurality of portions of the second wiring member  122 , via a plurality of conductive tapes  64   a . Thus, owing to the above-described arrangement, an impedance of a common voltage circuit is reduced, so that operations of the drive IC-chip  12   a  and the piezoelectric actuator  11  can be stabilized. 
     As another example of the conductor  64 , there may be adopted a conductive clip (i.e., a conductive member) which nips the first and second conductive layers  41   a ,  41   b  from the outside thereof. As shown in  FIG. 9B , if a conductive paper clip  64   b  made of a metal is adopted as the clip, a space required for setting the conductor  64  can be reduced because a thickness of the conductive paper clip  64   b  is small. Further, the conductive paper clip  64   b  can be easily attached to and removed from the second wiring member  122 . As compared to the conductive tape  64   a , the conductive paper clip  64   b  can be repeatedly attached or removed again and again, thereby lowering cost required for the components. 
     It is noted that the conductor  64  (e.g., the conductive tape, the conductive paper clip, etc.) is preferably disposed, in the flexible wiring member  12 , at a position away from a portion in which the piezoelectric actuator  11  is connected to the flexible wiring member  12 , namely, at a position nearer to a portion in which the head-side circuit board  22  is connected to the flexible wiring member  12 . As shown in  FIG. 3 , where the conductor  64  is attached to the flexible wiring member  12  at a position nearer to the portion in which the head-side circuit board  22  is connected thereto, the conductor  64  can be outwardly located or can be attached at a position so as to be easily reached by operator&#39;s hand from the outside. Therefore, the conductor  64  can be effectively and easily attached and removed even after the recording head  1  is assembled to the head holder  8 . 
     Other than the above-described conductor  64  such as the conductive tape and the conductive paper clip, there may be applied conducting means for establishing or breaking the electrical conduction between the first conductive layer  41   a  provided on the upper surface and the second conductive layer  41   b  provided on the lower surface. In this instance, a specific component like the conductor  64  may be not attached. Instead, as shown in  FIG. 9E , the second wiring member  122  per se may be folded such that the first conductive layer  41   a  is superposed on the second conductive layer  41   b . A manner for folding the second wiring member  122  are arbitrary, and the following is an exemplified process of the manner, as shown in  FIGS. 9C through 9E : (i) initially, the second wiring member  122  is folded up according to a broken line  65   a  that is inclined by an angle of 45 degree with respect to the longitudinal direction of the second wiring member  122 ; (ii) substantially, the second wiring member  122  is further folded up according to a broken line  65   b  that extends in a direction perpendicular to the longitudinal direction of the second wiring member  122 ; (iii) as a result, the first and second conductive layers  41   a ,  41   b  respectively provided on the upper and lower surfaces of the second wiring member  122  can be superposed on each other, so that the electrical conduction is established therebetween. When the fold of the second wiring member  12  is released, the electrical conduction between the first and second conductive layers  41   a ,  41   b  can be broken. A final state may be a state (shown in  FIG. 9E ) in which the flexible wiring member  12  is folded so as to be right-angled in a plane view. Instead, the final state may be a state in which the second wiring member  122  is further folded so that the second wiring member  122  has a straight shape as a whole. 
     It is noted that a concept of a conductor and a concept of conducting means are partially overlapped with each other. Therefore, one form of the conductor may become one form of the conducting means, and vice versa. In the present embodiment, each of the above-described conductors (e.g., the conductive tape  64   a  and the conductive clip such as the conductive paper clip  64   b ) may be regarded as one form of the conducting means. 
     As a conductor or conducting means, there may be adopted another conductor wire which is attached by a conductive material (e.g., a solder, an adhesive, etc.) so that the first and second conductive layers  41   a ,  41   b  are connected to each other via the same wire. However, as compared to the conductive tape  64   a , the conductive clip (e.g., the conductive paper clip  64   b ) and the above-described conducting means in which the flexible wiring member  12  is folded, the conductor wire is not easily attached and removed, thereby requiring a long time for the attachment or removal. Further, an operation of attaching or removing the conductor wire is complicated. Thus, it is not preferable to adopt the above-described another conductor wire as the conductor or the conducting means. 
     In the present embodiment, the first and second conductive layers  41   a ,  41   b  respectively provided in an entirety of the upper surface and an entirety of the lower surface of the second wiring member  122  are respectively connected to the first and second common voltage wires  61 ,  62  so as to be in parallel to each other. Therefore, the impedance of the common voltage circuit is reduced, so that the operations of the drive IC-chip  12   a  and the piezoelectric actuator  11  can be stabilized. 
     The conductive layers may be provided only in respective parts of a surface of the second wiring member  122 . Further, if impedances of the first and second common voltage wires  61 ,  62  are low, the first and second conductive layers  41   a ,  41   b  may be omitted. In this case, the electrical conduction may be established, by the conductor or the conducting means, between the terminal portions of the first and second common voltage wires  61 ,  62  each being outwardly folded and exposed in the outer surface of the second wiring member  122  in the above-described manner. 
     In the present embodiment, each of the first and second common voltage wires  61 ,  62  is constituted by stacking two conductor wires. However, the number of the conductor wires constituting each of the first and second common voltage wires  61 ,  62  may be more than three, or may be just one. If each of the first and second common voltage wires  61 ,  62  is constituted by one conductor wire, the same wire may be divided at a plurality of positions in a widthwise direction thereof and a one of the portions of the wire is folded and externally routed so as to be connected to the conductor or the conducting means. 
       FIG. 10  shows an example of an electrical circuit adopted in the present embodiment. In the ink-jet recording apparatus  100 , the body-side circuit board  90 , the head-side circuit board  22  and the drive IC-chip  12   a  are connected to one another. The body-side circuit board  90  is equipped with a control circuit  93 , a control-signal power source  94  and a drive-pulse power source  95 . The drive IC-chip  12   a  is constituted by including a signal-converting circuit  96  and the drive-voltage-signal generating circuit  97 . 
     The control circuit  93  is for outputting, to the signal-converting circuit  96 , control signals such as enable, data, clock, strobe signals, based on suitable recording information. The control circuit  93  is connected to the signal-converting circuit  96  via the signal lines  63  (the signal wires  63 ) for controlling. The control-signal power source  94  is for applying a voltage, e.g., a voltage of 5 V, to the signal-converting circuit  96  and is connected to the signal-converting circuit  96  via the drive conductor line VDD 1  for applying a drive voltage and the ground conductor line VSS 1 . The drive-pulse power source  95  is for applying a voltage, e.g., a voltage of 20 V, to the drive-voltage-signal generating circuit  97  and is connected to the same  97  via the drive conductor line VDD 2  and the ground conductor line VSS 2  (which corresponds to the second common voltage wire  62 ). 
     More specifically explained, the body-side circuit board  90  and the head-side circuit board  22  are connected via the flexible wiring member  99  including the drive conductor lines VDD 1 , VDD 2 , the ground conductor lines VSS 1 , VSS 2 , and the signal lines  63 , which lines are arranged on a plane of the flexible wiring member  99 . The drive IC-chip  12   a  mounted on the first wiring member  121  and the head-side circuit board  22  are connected via the second wiring member  122  including the above-described conductor lines and the conductor line VSS 3  which corresponds to a common voltage line COM (i.e., the first common voltage wire  61 ) and which is connected to the external common terminal  44  of the piezoelectric actuator  11 , which lines are arranged on a plane of the second wiring member  122 . 
     On the head-side circuit board  22 , an electrolysis capacitor  109  is bypass-connected between the drive conductor line VDD 2  and the ground conductor line VSS 2 . The electrolytic capacitor  109  charges an electric charge to be supplied to the drive-voltage-signal generating circuit  97  and prevents an occurrence of a drop in a case where a large number of the operable portions of the piezoelectric actuator  11  are driven almost at the same time. Further, when the recording is normally performed, the electrical conduction is established, by the above-described conductor  64  or the conducting means, between the ground conductor line VSS 2  (i.e., the second common voltage wire  62 ) and the conductor line VSS 3  (i.e., the first common voltage wire  61 ) which is joined to the external common terminal  44  of the piezoelectric actuator  11 . On the first wiring member  121  or in the drive IC chip  12   a , the ground conductor line VSS 2  and the ground conductor line VSS 1  are connected to each other via a resistance R, whereby the drive-voltage-signal generating circuit  97  and the signal-converting circuit  96  are kept at the same voltage. 
     The signal-converting circuit  96  is for converting the control signals from the control circuit  93  into control signals that correspond to the respective nozzles and includes shift registers  106 , D flip-flops  107 , and gate circuits  108 . The number of sets of the shift registers  106 , D flip-flops  107 , and gate circuits  108  is equal to the number of the nozzles. Among the control signals transmitted from the control circuit  93  via control-signal lines  63 , the data signals and the clock signals are sent to the shift registers  106 , the strobe signals are sent to the D flip-flops  107 , and the enable signals are sent to the gate circuits  108 . The data signals are serially transmitted from the control circuit  93 , converted by the shift registers  106  into parallel signals corresponding to rows of the nozzles, and outputted from the D flip-flops  107  based on the strobe signals. Then the enable signals (i.e., the drive pulse signals) corresponding to the data signals are outputted from the gate circuits  108 . 
     The drive-voltage-signal generating circuit  97  generates and outputs a drive pulse by converting, based on the voltage applied from the drive-pulse power source  95 , each enable signal (i.e., the drive pulse signal) outputted from the corresponding gate circuit  108  into a signal having a voltage for driving the piezoelectric actuator  11 . There are provided appropriate number of driver  110  (for example, 150 drivers) corresponding to the number of the nozzles. 
     In the thus constructed ink-jet recording apparatus  100 , the voltage to be applied from the control-signal power source  94  is applied to the signal-converting circuit  96  via the drive conductor line VDD 1 , thereby normally driving the signal-converting circuit  96 . The voltage to be applied from the drive-pulse power source  95  is applied to the drive-voltage-signal generating circuit  97  via the drive conductor line VDD 2  and at the same time permits the electrolytic capacitor  109  disposed therebetween to be charged. When the ink is ejected, there is supplied a current from the electrolytic capacitor  109  to the drive-voltage-signal generating circuit  97  via the drive conductor line VDD 2 , so that a sufficient amount of the current is supplied to the piezoelectric actuator  11 . 
     In a manufacturing process of the recording head  1 , the cavity portion  10  and the piezoelectric actuator  11  are stacked on each other, and the terminals (not shown) of the flexible wiring member  12  are respectively bonded, by a conductive material such as the solder, to the external individual terminal  43  and the external common terminal  44  of the piezoelectric actuator  11 . Then, a piezoelectric layer of the piezoelectric actuator  11  is polarized. In a polarizing process, as shown in  FIG. 11 , a polarizing device  111 , in place of the head-side circuit board  22 , is connected to the terminal portion  12   b  of the flexible wiring member  12 . 
     The polarizing device  111  includes a polarizing circuit  112  for generating a portion of polarizing electrical voltage and other electrical circuits for generating remaining portions of the electrical voltage. The above-described other electrical circuits are constituted by including the control circuit  93 , the control-signal power source  94 , and the drive-pulse power source  95  which are the equivalent of the body-side circuit board  90  for performing the above-described ink ejection. An operation of each of the control circuit  93 , the control-signal power source  94  and the drive-pulse power source  95  has been described above, thus a detailed explanation of which is dispensed with. 
     The polarizing circuit  112  is connected to the conductor line VSS 3  (i.e., the common voltage line COM or the first common voltage wire  61 ) which is joined to the common terminal that is common to all operable portions. Further, the polarizing circuit  112  includes a negative power source −VCC 2 , switches SW 1 , SW 2  and a resistance R 2 . 
     When each operable portion (more specifically described, a piezoelectric material of each portion which is to function as the operable portion) is polarized, the first and second conductive layers  41   a ,  41   b  respectively provided on the upper and lower surfaces of the second wiring member  122  are not connected to each other by the conductor  64  or the conducting means, so that the ground conductor line VSS 2  (i.e., the second common voltage wire  62 ) and the conductor line VSS 3  (i.e., the common voltage line COM or the first common voltage wire  61 ) are not electrically connected to each other. 
     In a state in which the polarizing device  111  is connected to the flexible wiring member  12 , both of the switches SW 1 , SW 2  are positioned in a side G (i.e., a ground side), namely, in a side in which the negative power source −VCC 2  and the conductive line VSS 3  are not connected to each other. In this state, all of the drivers  110  are operated by the control circuit  93 , the control-signal power source  94  and the drive-pulse power source  95  at the same time, thereby applying, to each operable portion, the same voltage (i.e., a voltage of V 1 ) as a voltage applied when the ink is to be ejected. The electrical voltage in this state has the same value as that in the ink ejection, so that the polarization is not performed. 
     Next, both of the switches SW 1 , SW 2  are moved to be positioned in a side N. In this state, a voltage of the negative power source −VCC 2  (i.e., a voltage of −V 2 ) is applied to each of the operable portions, and added to the applied voltage of V 1 . Thus, total voltage of (V 1 +V 2 ) is applied to each of the operable portions, whereby the polarization is performed thereon. After the polarization has been completed, the polarizing device  111  is removed from the flexible wiring member  12 . 
     When the recording head  1  is operated to perform the normal ink ejection, the conductor  64  is attached to the second wiring member  122 . In this state, the electrical conduction is established between the first and second conductive layers  41   a ,  41   b  respectively provided on the upper and lower surfaces of the second wiring member  122 , and the conductor line VSS 3  (i.e., the common voltage line COM or the first common voltage wire  61 ) is connected to the ground conductor line VSS 2  (i.e., the second common voltage wire  62 ), whereby the common electrode (i.e., the external common terminal  44 ) of the operable portions is grounded. Then, owing to the voltage (i.e., the voltage of V 1 ) selectively applied to the external individual terminals  43  via the drive IC-chip  12   a , the recording is performed by ejecting the ink from the desired nozzles of the recording head  1 . 
     When there are measured an amount of static electricity of the piezoelectric actuator  11 , a resistance value between each two of the operable portions, etc., for detecting a piezoelectric characteristic of the recording head  1 , the conductor  64  or the conducting means is removed from the second wiring member  122 . If the measurement is performed in a state in which the first and second voltage wires  61 ,  62  are joined to each other, a current via the drive IC-chip  12   a  is measured. This state causes a variation of consumption of the current of the drive IC-chip  12   a , deteriorating an accuracy of the measurement. However, as described above, the measurement in the inspection of the recording head  1  can be accurately performed because the conductor  64  or the conducting means can be easily removed, and the normal ink ejection can be performed because the conductor  64  or the conducting means can be easily attached. 
     In the present embodiment, the piezoelectric actuator is used as the actuator. However, the present invention may be equally applied to an actuator in which an ink is ejected by being heated and boiled, when a resistance value of heat-resisting elements thereof is measured. 
     It is to be understood that the invention is not limited to the details of the illustrated embodiments, but may be embodied with various changes and modifications, which may occur to those skilled in the art, without departing from the spirit and scope of the invention defined in the attached claims.