Ink-jet recording head

Segment terminal electrodes for connecting to the segment terminals of TCP and common terminal electrodes at both ends in a direction in which these segment terminal electrodes are arranged are formed on the surface of an actuator unit and the common terminal electrodes at both ends of each row are connected via conductive members. Each grounding conductor on TCP is mutually connected via each common terminal electrode component on the actuator unit. Therefore, the common terminal electrodes on plural actuator units can conduct to grounding conductors.

BACKGROUND OF THE INVENTION
 The present invention relates to an ink-jet recording head for jetting an
 ink droplet from a nozzle aperture by expanding and contracting the volume
 of a pressure generating chamber by a piezoelectric vibrator for flexural
 oscillation so as to print on recording medium. More specifically, the
 present invention relates to structure for connecting a piezoelectric
 vibrator and a cable.
 In an ink-jet recording head for jetting an ink droplet from a nozzle
 aperture by expanding and contracting the volume of a pressure generating
 chamber by a piezoelectric vibrator for flexural oscillation, a
 piezoelectric vibration plate is arranged on the surface of an elastic
 plate which is elastically deformable corresponding to each pressure
 generating chamber and a driving signal is applied to the piezoelectric
 vibration plate via a flexible cable.
 In such a flexible cable, signal lines of the same number as at least the
 number of piezoelectric vibrators and a common grounding conductor are
 normally formed on a insulating film in accordance with the array pitch of
 each piezoelectric vibration plate, each signal line is connected to one
 electrode of the piezoelectric vibrator and the grounding conductor is
 connected to the other electrode.
 Therefore, if the recording head is miniaturized or the array density of
 nozzle apertures is enhanced, the width of a signal pattern formed in the
 flexible cable for supplying a driving signal to each piezoelectric
 vibrator is necessarily narrowed and its electrical resistance is
 increased.
 As a result, the electric potential difference from the grounding conductor
 of each piezoelectric vibrator varies, the quantity in which the
 piezoelectric vibrator is displaced varies and there is a problem that as
 a result, the characteristic of jetting an ink droplet varies depending
 upon a nozzle aperture.
 To reduce the increase of electrical resistance in a signal pattern, tape
 carrier package (TCP) technology for mounting a semiconductor integrated
 circuit for generating a driving signal in an area as close to a
 piezoelectric vibrator as possible of a flexible cable is adopted. Hereby,
 as the distance in which a driving signal is transmitted can be reduced,
 the variation among nozzle apertures of the characteristic of jetting an
 ink droplet can be reduced.
 However, as to realize color printing and high density printing by
 arranging plural rows of pressure generating chambers in one head,
 distance between nozzle apertures in each row is required to be reduced as
 much as possible and the precision of fixing ink on a dot is required to
 be secured, a terminal for connecting to the grounding conductor, a
 so-called common terminal can be provided to only one end of a terminal
 for supplying a driving signal to the piezoelectric vibrator, a so-called
 segment terminal row.
 Therefore, there occurs a new problem that large distance is made between
 the common terminal electrode located at the other end for piezoelectric
 vibrators and the grounding conductor, the characteristic of displacement
 varies among piezoelectric vibrators in the same row and among
 piezoelectric vibrators in different rows and the characteristic of
 jetting an ink droplet varies.
 Particularly, in a recording head using a piezoelectric vibrator utilizing
 flexural displacement, the electrode which is formed on the surface of an
 elastic plate, as a lower electrode is required to be formed as thinly as
 possible to maintain the elasticity of the elastic plate, electrical
 resistance is increased and the above problem is more realized.
 To solve such problem, a method of increasing the area of the TCP and
 providing a grounding conductor outside is also conceivable, however,
 there is a problem that the size of the whole recording head is increased.
 For a recording head using TCP in which a driving signal generating
 semiconductor integrated circuit is mounted on a flexible cable, there is
 a problem that as the rigidity of the flexible cable is increased, the
 characteristic related to oscillation of a piezoelectric vibrator varies
 due to deformation when TCP is connected to a recording head chip and
 contact between TCP and a piezoelectric vibrator and the characteristic of
 jetting ink is influenced.
 SUMMARY OF THF INVENTION
 An ink-jet recording head according to the present invention is provided
 with plural nozzle openings for jetting ink, a piezoelectric vibrator for
 expanding or reducing the volume of a pressure generating chamber
 communicating with a nozzle aperture, a segment terminal electrode
 provided corresponding to the above piezoelectric vibrator and connected
 to one pole of the piezoelectric vibrator and a common terminal electrode
 arranged at both ends in a direction in which the segment terminal
 electrodes are arranged and connected to the other pole of the
 piezoelectric vibrator, a tape carrier package having a segment terminal
 connected to the segment terminal electrode and having the relationship of
 continuity to a signal pattern for transmitting a driving signal generated
 based upon an input signal from an external device, a common terminal
 located at both ends of the segment terminal and connected to the common
 terminal electrode and a grounding conductor arranged on both sides and on
 the side of the input signal pattern and connected to the common terminal
 and a connecting member arranged at both ends of the segment terminal
 electrode for connecting the common terminal electrode. Owing to such
 constitution, the common terminal electrode formed at both ends of the
 actuator unit is securely connected to the grounding conductor in an area
 of the actuator unit and the electric potential of the piezoelectric
 vibrator can be prevented from varying.
 Therefore, a first object of the ink-jet recording head according to the
 present invention is to provide an ink-jet recording head in which the
 electric potential of piezoelectric vibrators in plural rows is fixed
 possibly and an ink droplet can be stably jetted without increasing the
 size of the whole recording head.
 A second object of the ink-jet recording head according to the present
 invention is to provide an ink-jet recording head in which TCP and a
 piezoelectric vibrator are prevented from coming in contact and an ink
 droplet can be stably jetted.

PREFERRED EMBODIMENTS OF THE INVENTION
 Embodiments showing the details of the present invention in the drawings
 will be described below. However, in FIG. 1, a group of terminals 251a to
 254a and 241 to 246 exposed on the rear side of TCP 2 are shown on the
 surface side to assist understanding.
 An ink-jet recording head comprises a head chip 1 including a nozzle plate
 11, a reservoir plate 12 and plural actuator units 30 (three actuator
 units 30 are provided in this embodiment), and TCP 2 for supplying a
 driving signal to each actuator unit 30 as shown in FIG. 1.
 TCP 2 is made such that a driving signal generating semiconductor
 integrated circuit 21 for generating a driving signal according to a
 printing signal from a host not shown is mounted on a flexible cable, and
 a required wiring pattern is formed.
 Each actuator unit 30 provided to the head chip 1 is arranged corresponding
 to adjacent each two rows in six rows of nozzle apertures 111 provided to
 the nozzle plate 11.
 A recording head in which ink of different colors is jetted from a nozzle
 aperture 111 in each row and printing in six colors of ink is enabled can
 be constituted by such constitution and a recording head in which the
 arrangement of two nozzle aperture rows corresponding to one actuator unit
 30 is shifted by half pitch and higher density printing in three colors of
 ink is enabled can be achieved by such constitution.
 The semiconductor integrated circuit 21 for generating the driving signal,
 mounted on TCP 2, is connected to an input signal pattern 22 for supplying
 a printing signal from a host and an output signaL pattern 23 for
 outputting a driving signal generated by the semiconductor integrated
 circuit 21 to each actuator unit 30, and the signal patterns 22 and 23 are
 covered with a resist layer not shown with only a connecting area exposed.
 In the connecting area of the output signal pattern 23, segment terminals
 241 to 246 are provided in accordance with the arrangement pitch of
 connecting terminals 371 to 376 of the actuator unit 30.
 Grounding conductors 251 and 252 are provided at one end of the segment
 terminals 241 and 246 on both sides of TCP 2, grounding conductors 253 and
 254 installed on the side of the semiconductor integrated circuit 21 are
 provided between adjacent segment terminals 242 and 243 and between 244
 and 245 and further, grounding conductors 255, 256 and 257 are provided on
 the side of each end of the segment terminals 241 to 246, that is, on the
 side far from the semiconductor integrated circuit 21 so that each
 actuator unit 30 is crossed.
 Grounding conductors 251 and 252 are respectively divided into plural parts
 (three in this embodiment) in an area in which each grounding conductor is
 connected to each common terminal electrode 381a and 386a described later
 and connecting terminals 251a and 252a are formed.
 Similarly, grounding conductors 255, 256 and 257 are respectively divided
 into plural parts (three in this embodiment) in an area in which each
 grounding conductor is connected to each common terminal electrode 382a to
 385a described later and connecting terminals 253a to 254a' are formed.
 In the meantime, segment terminal electrodes 371 to 376 for respectively
 connecting to the segment terminals 241 to 246 by soldering and others are
 formed on the surface of the actuator unit 30, common terminal electrodes
 381a, 381b to 386a and 386b are formed at both ends in a direction in
 which the segment terminal electrodes 371 to 376 are arranged, these
 common terminal electrodes 381a, 381b to 386a and 386b in each row extend
 in a direction in which the segment terminal electrodes 371 to 376 are
 arranged in the central area of the actuator unit 30 and are respectively
 connected via conductive members 381c to 386c formed by the same method as
 the segment terminal electrodes 371 to 376 and the common terminal
 electrodes 381a to 386b.
 For these common terminal electrode forming members 381a-386a and 381b-386b
 and conductive members 381c-386c, explaining the common terminal electrode
 forming member 381 as an example, the common terminal electrode forming
 member 381 is provided with ends 381a and 381b for connecting to TCP 2 on
 the side of the end in a direction in which the segment terminal electrode
 371 is arranged and particularly, the common terminal electrode 381a on
 the side of the semiconductor integrated circuit is divided into plural
 parts (three in this embodiment).
 In case TCP 2 is connected to the head chip 1, each grounding conductor 251
 to 257 of TCP is mutually connected via each common terminal electrode
 381a-386a and 381a-386b and conductive members 381c-386c on the actuator
 unit 30 owing to such connecting structure. That is, the grounding
 conductor 251 is connected to the common terminal electrode 381a of three
 parts via the common terminal 251a and is connected to the common terminal
 electrode 381b at the other end via the conductive member 381c extended in
 the central area of the actuator unit 30. The common terminal electrode
 381b and the common terminal electrode 382b on the other side of the same
 actuator unit 30 are connected via the grounding conductor 255 of TCP 2
 and connected to the common terminal electrode 382a at the other end via
 the conductive member 382c. The common terminal electrode 382a is
 connected to the common terminal 253a of the grounding conductor 253 of
 TCP 2, is connected to the common terminal 253a' on the opposite side via
 the grounding conductor 253 and is connected to the common terminal 253a
 of the other adjacent actuator unit 30. In the same actuator unit 30, the
 grounding conductors 251 and 252 arranged on both sides of TCP 2 can be
 connected via the conductive members 381c to 386c and the grounding
 conductors 255 and 257 arranged at the end far from the semiconductor
 integrated circuit 21 of TCP 2, and between adjacent actuator units 30,
 the grounding conductors 251 and 252 arranged on both sides of TCP 2 can
 be connected via the grounding conductors 253 and 254 on the side of the
 semiconductor integrated circuit 21.
 Therefore, the common terminal electrodes 381a, 381b to 386a and 386b on
 the actuator units 30 can be securely connected to the grounding
 conductors 251 and 252 independent of the number of the actuator units 30.
 The common terminal electrodes 381a to 386a at the end of each common
 terminal electrode 381 to 386 and on the side of the semiconductor
 integrated circuit 21 are formed so that they are more than the common
 terminal electrodes 381b to 386b at the other end and each total area is
 larger, and the corresponding pattern structure is applied to the
 grounding conductors 251 to 254 of TCP 2. Owing to such structure, even if
 one of three common terminals 251a of the grounding conductor 251 for
 example respectively connected to the three common terminal electrodes
 381a is peeled because of the bending stress of TCP 2 in case TCP 2 is
 bent into two between an area in which segment terminals and common
 terminals are formed and the semiconductor integrated circuit 21, that is,
 along a line A--A in FIG. 1 and assembled if the whole recording head is
 miniaturized, continuity can be kept by the residual two. As the heat
 capacity of one common terminal electrode 381a is small because the common
 terminal electrode is divided, soldering is facilitated, compared with a
 case that the common terminal electrode is not divided.
 Referring to FIG. 3, the structure of the segment terminal electrode will
 be described in detail below, referring to FIG. 4, the common terminal
 electrode forming member will be described in detail below and further,
 referring to FIG. 5, the superficial structure of the actuator unit 30
 will be described in detail below.
 In the head chip 1, the nozzle plate 11 in which nozzle apertures 111 for
 respectively jetting ink as an ink droplet are made and the reservoir
 plate 12 in which reservoirs 121 for respectively supplying ink to each
 pressure generating chamber 32 are formed are bonded fluid-tight by a
 thermically welding film not shown and others, and the actuator unit 30 is
 bonded fluid-tight on the surface.
 In the actuator unit 30, a pressure generating chamber forming member 31 in
 which plural pressure generating chambers 32 respectively communicating
 with the reservoir 121 and each nozzle aperture 111 are formed and an
 elastic plate 33 for sealing one surface of the pressure generating
 chamber 32 are baked integrally via ceramic material, a lower electrode 34
 as the other pole is formed on the surface of the elastic plate 33, a
 piezoelectric vibrator 35 is formed on the surface and further, an upper
 electrode 36 as one pole is formed on the surface of the piezoelectric
 vibrator 35.
 The lower electrode 34 is formed by platinum (Pt) corresponding to each
 pressure generating chamber 32 so that it is 1 to 5 .mu.m thick, as shown
 in FIG. 5, each is connected via a central area 34a and further,
 conductive members 381c and 382c are formed by silver (Ag) 10 to 20 .mu.m
 thick on the surface of the central area 34a.
 As described above, as the lower electrode 34 is also connected to the
 conductive members 381c and 382c, resistance between each grounding
 conductor 251 and 252 and the lower electrode 34 is decreased, compared
 with a case that the lower electrode is connected to the grounding
 conductors 251 and 252 only at one end in a direction in which the segment
 terminal electrodes 371 and 372 are arranged, and the electric potential
 of the lower electrode 34 can be prevented from varying. If a dummy lower
 electrode 341 is formed so that the lower electrode 34 and the lower
 electrode 34 are disconnected because of clearance 341a and others,
 joining strength between the piezoelectric vibrator 35 and the elastic
 plate 33 is readily secured.
 In the meantime, the upper electrode 36 is formed by gold (Au) 0.1 to 1
 .mu.m thick on the surface of the piezoelectric vibrator 35 formed
 corresponding to the lower electrode 34 so that the piezoelectric vibrator
 is 5 to 15 .mu.m thick, and the segment terminal electrodes 371 and 372
 respectively connected to the connecting terminals 241 and 242 of TCP 2
 are formed by silver (Ag) 10 to 20 .mu.m thick at the end.
 The thickness G of the segment terminal electrodes 371 and 372 and the
 common electrode forming members 381 and 382 is set to the thickness of
 the piezoelectric vibrator 35 or a larger value, and a step g (see FIG. 3)
 is secured between the piezoelectric vibrator 35 corresponding to each
 segment terminal electrode 371 and 372 and each common terminal electrode
 forming member 381 and 382. Hereby, TCP 2 is located via space between it
 and the piezoelectric vibrator 35 and mechanical contact between TCP 2 and
 the piezoelectric vibrator 35 can be prevented.
 As the thickness G of each segment terminal electrode 371, 372, 381 and 382
 is large, resistance in the whole conductor including the common terminal
 electrode forming members 381 and 382 is decreased and the variation of
 electric potential in the lower electrode 34 can be prevented.
 As described later, desirably, as shown in FIGS. 6 and 7, a large step g is
 made between the piezoelectric vibrator 35 and each common terminal
 electrode 381a, 381b, 382a and 382b by forming dummy piezoelectric
 vibrators 351 and 352 in an area not opposite to the nozzle aperture 111
 and mounting the common terminal electrode forming members 381 and 382 on
 the surface, and mechanical contact between TCP 2 and the piezoelectric
 vibrator 35 can be securely prevented.
 In the ink-jet recording head constituted as described above, a driving
 signal is generated in the driving signal generating semiconductor
 integrated circuit 21 corresponding to a printing signal from an external
 device such as a host. The driving signal is applied to the segment
 terminal electrode 371 of the head chip 1 via the pattern 23 of TCP 2 and
 the segment terminal 241.
 The piezoelectric vibrator 35 is flexuously displaced by an electric field
 between the upper electrode 36 connected to the segment terminal electrode
 371 and the lower electrode 34 connected to the grounding conductor 251
 via the common terminal electrode 381. Hereby, the elastic plate 33 is
 displaced, ink in the pressure generating chamber 32 is pressurized and an
 ink droplet is jetted from the nozzle aperture 111 according to a printing
 signal.
 According to this embodiment, as a driving signal is supplied from one TCP
 2 to plural actuator units 30, the recording head can be miniaturized,
 compared with a case that independent TCP is provided every actuator unit.
 At that time, as the plural grounding conductors 251 and 252 of TCP 2 are
 mutually connected via the common terminal electrode forming members 371
 and 372 in one actuator unit 30, the common terminal electrodes 371 and
 372 in one actuator unit 30 are grounded at the minimum floating potential
 and an electric field applied to each piezoelectric vibrator 35 is
 equalized. Hereby, the displaced quantity of each piezoelectric vibrator
 35 of the whole head chip is fixed, an ink droplet with fixed volume can
 be jetted from each nozzle aperture 111 and high quality of printing is
 enabled.
 FIGS. 6 and 7 show a second embodiment of the ink-jet recording head
 according to the present invention.
 In a process for forming a piezoelectric vibrator 35 on a lower electrode
 34 on the surface of an elastic plate 33 of an actuator unit 30, dummy
 piezoelectric vibrators 351 and 352 are respectively formed in the center
 and on both sides of the actuator unit 30.
 In a process for forming an upper electrode 36 on the piezoelectric
 vibrator 35, the upper electrode 36 is formed on the dummy piezoelectric
 vibrator 351 on both sides of the actuator unit 30, a dummy upper
 electrode 361 not connected to the upper electrode 36 is formed on the
 dummy piezoelectric vibrator 352 in the center and further, segment
 terminal electrodes 381 and 382 connected to TCP 2 are formed on the
 surface of these upper electrodes 36 and 361.
 According to this embodiment, the height from the elastic plate in an area
 in which the segment terminal electrodes 371 and 372 and the common
 electrode forming members 381 and 382 are formed can be made higher by the
 thickness of each dummy piezoelectric vibrator 351 and 352 than the height
 in an area in which the piezoelectric vibrator 35 is formed only by
 changing the shape of an electrode forming pattern and others without
 greatly changing the manufacturing process of the ink-jet recording head
 equivalent to the first embodiment, a gap g' between TCP 2 and the
 piezoelectric vibrator 35 is sufficiently secured and contact between TCP
 2 and the piezoelectric vibrator 35 can be securely prevented.
 FIGS. 8 and 9 show a third embodiment of the ink-jet recording head
 according to the present invention. In this embodiment, conductive members
 381c to 386c for connecting the common terminal electrodes 381a, 381b to
 386a, 386b arranged at both ends in a direction in which the segment
 terminal electrodes 371 to 376 are respectively arranged are not required
 and instead, the common terminal electrodes 381a, 381b to 386a, 386b
 arranged at both ends in a direction in which these segment terminal
 electrodes 371 to 376 are respectively arranged are connected via an
 external conductive member. An anisotropic conductive bonding film 6 is
 provided for connecting TCP 2 and a terminal which effects conductivity
 only in a pressurized direction and the above film is formed by mixing
 thermoplastic polymeric material and minute powder of metal and extending
 to be a film.
 As shown in FIG. 10, TCP 2 in this embodiment is formed by mounting a
 semiconductor integrated circuit 21 for generating a driving signal on a
 flexible cable as in the above embodiments, segment terminals for
 connection 241 to 246 are provided corresponding to the actuator unit 30
 and grounding conductors 251 and 252 are provided on the side of the
 semiconductor integrated circuit 21 of the segment terminals 241 and 246
 on both sides of TCP 2.
 Similar grounding conductors 253 and 254 to those in the above embodiments
 are provided at one end between adjacent segment terminals 242 and 243 and
 between 244 and 245 and further, triangular grounding areas 261, 262 and
 263 provided with larger area than the area of grounding conductors 255 to
 257 are provided at the end of the segment terminals 241 to 246.
 Windows 251a, 252a, 261a and 263a which can be connected to an area
 opposite to the conductive pattern 500 of a substrate 5 described later by
 soldering and others are formed in the grounding conductors 251 and 252
 and the grounding areas 261 and 263 at both ends of the grounding areas
 261 to 263 at the end.
 Common terminals 251b and 252b respectively composed of three parts
 connected to common electrode terminals 271a and 276a of the actuator unit
 30 are formed at the end of the grounding conductors 251 and 252, common
 terminals 261b to 263b respectively composed of three parts are formed at
 the end of grounding areas 261 and 263 and further, common terminals 253b,
 253b', 254b and 254b' respectively composed of three parts are formed at
 the end of grounding conductors 253 and 254.
 The substrate 5 is a glass epoxy substrate as shown in FIG. 11 and a
 conductive pattern 500 provided with terminal parts 501 and 502 connected
 respectively via the windows 251a and 252a of TCP 2 and terminal parts 503
 and 504 connected respectively via the windows 261a and 263a is formed.
 Hereby, when TCP 2 and the substrate 5 are soldered in the areas of the
 windows 251a to 263a, common connecting terminals 261b and 263b at the end
 are respectively connected to the grounding conductors 251 and 252 via
 conductive patterns 505 and 506 of the substrate 5.
 Hereby, when bonding between TCP 2 and the substrate 5 is finished, the
 recording head is completed by bonding each terminal of TCP 2 to the
 terminal electrode of the head chip 1 as in the above embodiments by the
 anisotropic conductive film 6 and soldering.
 In this embodiment, as in the above embodiments, as the recording head is
 also miniaturized by connecting one TCP 2 to plural actuator units 30 and
 the plural grounding conductors 251 and 252 of TCP 2 are connected via the
 common terminal electrode of each actuator unit 30 and the conductive
 pattern of the substrate 5, the common terminal electrode of each actuator
 unit 30 is grounded at the minimum floating potential and an electric
 field applied to the piezoelectric vibrator 34 is equalized. Hereby, the
 displaced quantity of the piezoelectric vibrators 34 of the whole head
 chip is fixed, fixed quantity of ink can be stably jetted from each nozzle
 aperture 111 as an ink droplet and high quality of printing is enabled.
 FIGS. 12 and 13 show a fourth embodiment of the ink-jet recording head
 according to the present invention, in this embodiment, the substrate 5 in
 the third embodiment is formed by TCP 2, and the end and both sides of TCP
 2 are bent.
 In TCP 2, an auxiliary wiring part 270 which fulfills the similar function
 to the above substrate 5 is formed at the end as shown in FIG. 14 with
 plural slits 281 between the auxiliary wiring part and the semiconductor
 integrated circuit.
 In the auxiliary wiring part 270, a conductive pattern 271 in the same
 shape as the conductive pattern 500 of the above substrate 5 is formed.
 Windows 272 and 273 for exposing terminal parts to which the conductive
 pattern 271 conducts via windows 251a and 252a of TCP 2 when TCP is bent
 with the slits 281 in the center and terminal parts 274 and 275 which
 conduct via windows 261a and 263a are formed.
 On both sides of an area in which terminals 241 to 246 respectively
 connected to a head chip 1 are formed, extended parts 276 and 277 are
 formed with the slits 282 between and auxiliary grounding conductors 251c
 and 252c for connecting common electrode terminals 261b and 263b are
 formed on the surface of these.
 In this embodiment, as shown in FIGS. 12 and 13, the extended parts 276 and
 277 of TCP 2 are respectively bent inside with the slits 282 in the
 center, next, the auxiliary wiring part 270 is bent with the slits 281 in
 the center, grounding conductors 251 and 252 respectively exposed from the
 windows 251a and 252a of TCP 2, the conductive pattern 271 exposed from
 the windows 272 and 273 of the auxiliary wiring part 270 and grounding
 areas 261 and 263 respectively exposed from the windows 261a and 263a of
 TCP 2 are soldered for continuity, and the auxiliary wiring part 4 and TCP
 5 are fixed with them bent. The ink-jet recording head is completed by
 soldering TCP 2 bent in a predetermined shape and reduced as described
 above on the head chip 1.
 In this embodiment, the recording head can be thinned by the quantity
 because it has no substrate 5, simultaneously as in the above embodiments,
 the plural grounding conductors 251 and 252 of TCP 2 are connected via the
 common terminal electrode of each actuator unit 30, further, as the common
 terminals 251a and 251b, 252a and 252b in an area at the end in a
 direction in which common electrodes on both sides are arranged are
 connected via the auxiliary grounding conductors 251c and 252c in the
 extended parts 276 and 277, the common terminal electrode of each actuator
 unit 30 is grounded at the minimum floating potential and an electric
 field applied to each piezoelectric vibrator is equalized. Hereby, the
 displaced quantity of each piezoelectric vibrator in the whole head chip
 is fixed, an ink droplet can be stably jetted from each nozzle aperture
 111 and high quality of printing is enabled.
 In this embodiment, flexible cable components are effectively utilized by
 forming the auxiliary wiring part 270 at the end, however, similar action
 is produced by forming the auxiliary wiring part 270 in a cross direction,
 that is, forming it on one side or on both sides as the extended part 276
 in FIG. 14 and forming it in size enough to reach the windows 251a, 252a,
 261a and 263a when bent.