JP5233398B2 - Recording head and image forming apparatus for droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge device that discharges droplets from a droplet discharge head onto a recording medium to form a high-definition image, and a diaphragm generates a part of a pressure generation chamber that communicates with a nozzle opening. The present invention relates to a recording head and an image forming apparatus of a droplet discharge device configured to discharge a droplet by changing the volume in a liquid chamber by displacement of a piezoelectric element.

  In general, an ink jet recording apparatus (droplet discharge apparatus) is known as means for printing on various recording media such as paper and film. The ink jet recording apparatus supplies ink from an ink tank to a liquid discharge head via a supply tube, and applies a voltage to the piezoelectric element such as a piezo using the supplied ink. Thus, ink is ejected from the nozzle of the liquid ejection head onto the recording medium, and the above operation is repeated on the recording medium, thereby forming a high-definition image on the recording medium.

  Inkjet recording devices do not require plate making, unlike conventional offset printing, so they do not require a plate making process, but can also respond immediately to small lot printing, and print according to demand. Make it possible.

  Particularly in recent years, high quality and durability are demanded for printed matter, and the development of ink for that purpose has been progressing rapidly as well as printing devices. Thus, in order to satisfy the requirements for printed matter, stable ejection is required.

  A part of the pressure generating chamber communicating with the nozzle opening is constituted by a vibration plate, and the vibration plate is used to change the body volume in the liquid chamber due to the displacement of the piezoelectric element to discharge a liquid droplet. Some use a longitudinal vibration mode piezoelectric actuator that expands and contracts in the direction. Since these methods can easily change the volume of the pressure generating chamber by bringing the end face of the piezoelectric element into contact with the diaphragm, a head suitable for high-density printing can be manufactured. A difficult manufacturing process of cutting in a comb shape in accordance with the arrangement pitch of the nozzle openings and a process of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required. Furthermore, in a droplet discharge head in which piezoelectric elements are arranged at a high density, it is necessary to simultaneously drive a large number of piezoelectric elements and simultaneously discharge a large number of ink droplets. There is a problem in that the amount of displacement of the element becomes unstable and the droplet discharge characteristics deteriorate. Moreover, the applied voltage tends to be lower as the piezoelectric element is located farther from the connection portion to which the external wiring is connected. For this reason, even if the piezoelectric elements are arranged in a line, there is a problem in that the droplet discharge characteristics vary depending on the distance from the connecting portion.

  The electrode of such a piezoelectric element is formed of a thin film, and since its film thickness is very thin, the resistance value tends to be relatively high, and the above problem is likely to occur. In order to solve such a problem, a plurality of connection portions to which an external wiring connected to a drive circuit for driving the piezoelectric element is provided on a common electrode common to the plurality of piezoelectric elements, and the plurality of connections are provided. A method is employed in which the resistance values of the common electrode are substantially reduced by connecting the portions by wiring electrodes provided on the common electrode.

  Another solution is to increase the thin film thickness and decrease the resistance value when the electrodes of the piezoelectric element are formed by vapor deposition or sputtering.

As a technical example related to the present invention, Patent Document 1 includes a plurality of connection portions to which external wirings connected to a drive circuit for driving a piezoelectric element are provided on a common electrode common to the piezoelectric elements, and these An “ink jet recording head and ink jet recording apparatus” is disclosed in which a resistance value of a common electrode is substantially reduced by connecting a plurality of connecting portions by wiring electrodes provided on the common electrode.
JP 2003-118110 A

  However, a plurality of connection portions to which external wirings connected to a drive circuit for driving the piezoelectric elements are connected on a common electrode common to the plurality of piezoelectric elements, and the plurality of connection portions can be provided on the common electrode. In the connection method using wiring electrodes, the configuration and wiring of the head itself are complicated and the number of components is increased by providing separate wiring.

  In addition, when the electrodes of piezoelectric elements are formed by vapor deposition and sputtering, the method of increasing the thin film thickness and decreasing the resistance value increases the vapor deposition and sputtering time and affects the tact manufacturing tact. This leads to an increase in material cost. In particular, when an expensive material such as gold is used as an electrode, the cost of the head alone is increased.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a recording head and an image forming apparatus of a droplet discharge device that can satisfactorily maintain droplet discharge characteristics with the current head component configuration.

The means of the present invention for achieving this object will be described below.
In the first aspect of the present invention, an actuator element that applies pressure to individual liquid chambers provided corresponding to a plurality of nozzles is selectively driven by a drive signal from a head drive circuit at a predetermined printing timing, A recording head of a droplet discharge device that discharges ink droplets from corresponding nozzles to perform recording on a recording medium, and performs a function different from a conductive purpose apart from a common electrode portion on the ground side of each actuator element A liquid characterized in that a conductive loop is provided in the head component and the driving IC on-resistance for driving the actuators arranged in a row becomes smaller as the distance from the connection portion becomes longer. It is in the recording head of the ejection device.

Such a first state-like, without the need for special additional wiring, also does not require additional components, since the resistance value of the common electrode at existing head components is substantially reduced, the number of actuator elements Even when driven at the same time, voltage drop does not occur and the droplet discharge characteristics are stabilized.

A second aspect of the present invention, first Oite the state like the head component comprising a separate conductive loops and the liquid common electrode portions of the ground side of each actuator element of the recording head of the droplet ejection apparatus of the present invention Is a head base for fixing the actuator element.

In the second aspect, by using the head base in which the actuator element is fixed to the head component that becomes the conductive loop as the common electrode, the resistance value of the common electrode is effectively prevented from being lowered, and a large number of actuator elements can be simultaneously used. Even when driven, the droplet discharge characteristics are stabilized without causing a voltage drop.

According to a third aspect of the present invention, in the second aspect of the present invention, a conductive material is used for a head base which is a head component for fixing the actuator element.

In the third aspect, the material used for the head base is not characterized by the conductive characteristics such as a semiconductor, and a signal can be efficiently transmitted to the actuator element by using a complete conductor.

According to a fourth aspect of the present invention, in the third aspect of the present invention, SUS is used as a material for the head base.

In the fourth aspect, by using SUS for the material of the head base, in addition to performing the actuator fixing function that is the original purpose in terms of material strength, resonance problems that affect stable ejection, and further material for long-term use It is a material with excellent durability such as corrosion, and by using this SUS as a head base material, stable discharge can be maintained.

A fifth aspect of the present invention, Oite the first state like the present invention, characterized by depositing the at common electrode portion of the gold sputter the ground side of each actuator element.
In the fifth aspect, the common electrode surface on the ground side is formed by gold sputtering, so that even if the adhesive is non-conductive, the sputter surface is a needle electrode due to the nature of the film formation process. It is formed with such a fine uneven surface, and can be electrically connected to the head base at the time of pressure bonding.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the sputtered film thickness of gold in the common electrode portion on the ground side of each actuator element is 0.4 μm or less.

In the sixth aspect, it is possible to provide a head that does not increase the resistance value of the common electrode portion even if the sputtering thickness is reduced. Further, by reducing the sputtering thickness, the head cost can be reduced.

According to a seventh aspect of the present invention, there is provided the recording head of the droplet discharge device according to any one of the first to sixth aspects of the present invention.

In the seventh aspect, it is possible to provide a low-cost and high-quality image forming apparatus.

  According to the present invention, the resistance value of the common electrode is substantially reduced in the existing head component without the need for special additional wiring and the need for additional components. However, it is possible to stabilize the droplet discharge characteristics without causing a voltage drop.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram of a droplet discharge head (a recording head of a droplet discharge apparatus) as an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view in the width direction of the liquid chamber of the droplet discharge head according to the present embodiment.

  1 and 2, the flow path plate 103 is formed, for example, by anisotropic etching of a single crystal silicon substrate. A diaphragm 104 formed by nickel electroforming or the like is joined to the lower surface of the flow path plate 103. A nozzle plate 102 is bonded and laminated on the upper surface of the flow path plate 103.

  In this way, the diaphragm 104 bonded to the lower surface of the flow path plate 103, for example, formed by nickel electroforming, and the nozzle plate 102 bonded to the upper surface of the flow path plate 103 are bonded and stacked. As a result, a nozzle communication path 202 which is a flow path through which a nozzle 201 for discharging droplets (ink drops) communicates, a pressurized liquid chamber 203, and a common liquid chamber 204 for supplying ink to the pressurized liquid chamber. An ink supply port 205 or the like communicating with the ink is formed.

  In the present embodiment, the diaphragm 104 is deformed to pressurize the ink in the pressurized liquid chamber 203, so that two rows of stacked piezoelectric elements are used as electromechanical conversion elements as pressure generating means (actuator means). 107 and a head base 108 for bonding and fixing the piezoelectric element. Here, the height H of the pressurized liquid chamber 203 is formed to 90 μm. Thus, the pressurized liquid chamber 203 is lifted by driving due to insufficient rigidity of the partition wall, that is, the partition wall is prevented from being bent by a force in a direction in which the diaphragm 104 is displaced, and the discharge stability can be secured.

  The piezoelectric element 107 is connected to an FPC board 106 on which a drive circuit (driver IC) is mounted.

  Here, the flow path plate 103 is formed by, for example, subjecting a single crystal silicon substrate having a crystal plane orientation to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution, so that the nozzle communication path 202, the pressurized liquid chamber 203, and the like. The recessed part and hole part which become are formed. In this way, by using single crystal silicon as the liquid chamber material, it is possible to ensure a highly accurate dimension and to form the highly rigid pressurized liquid chamber 203, and to improve the stabilization of the injection characteristics and The natural period can be shortened.

  The material of the flow path plate described above is not particularly limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used. However, it is possible to prevent the partition wall from being bent due to the force in the direction in which the pressurized liquid chamber 203 is lifted (the vibration plate is displaced) due to insufficient rigidity, and a pressure drop in the pressurized liquid chamber 203 is generated. In order to facilitate the shortening, it is desirable to use a highly rigid material having an elastic modulus of 100 GPa or more.

  Next, the vibration plate 104 of the present embodiment is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition to this, a metal plate or a metal and resin plate is used. A joining member or the like can also be used. The piezoelectric element 107 is bonded to the diaphragm 104 with an adhesive, and the head frame 105 is further bonded with an adhesive.

  The nozzle plate 102 forms a nozzle having a diameter of 24 μm corresponding to each pressurized liquid chamber, and is bonded to the flow path plate with an adhesive. The nozzle plate 102 is formed by forming a water repellent layer on the outermost surface of a nozzle forming member made of a metal member via a required layer. The surface of the nozzle plate 102 becomes a nozzle surface.

  Here, by setting the nozzle diameter to 24 μm, it is possible to eject a droplet of 2 pl or less. In addition, since the droplet velocity does not become too fast, the droplets can be merged in the air when forming a large droplet by multi-pulse driving, thereby enabling high image quality formation. The nozzle diameter is most preferably 24 μm. However, by setting the nozzle diameter to 20 to 25 μm, small droplet discharge is facilitated, and since the droplet velocity does not become too fast, large droplets can be formed by multi-pulse driving. .

  As the piezoelectric element 107, a stacked piezoelectric element 301 (here, PZT: piezo) in which piezoelectric materials and internal electrodes are alternately stacked in FIG. 3 is used. The individual electrodes 302 and the common electrode 303 are connected to the internal electrodes that are alternately drawn to different end faces of the laminated piezoelectric element 301. In the present embodiment, the ink in the pressurized liquid chamber 203 is pressurized using a displacement in the direction indicating the expansion and contraction perpendicular to the electrode surface (thickness direction) as the piezoelectric direction of the laminated piezoelectric element 301. By adopting such a configuration, it is possible to provide a liquid droplet ejection head (FIG. 4) that has small compliance, high rigidity, and high-speed driving.

  In the liquid droplet ejection head of the present embodiment shown in FIG. 4 configured as described above, first, the multilayer piezoelectric element 301 contracts by lowering the voltage applied to the multilayer piezoelectric element 301 from the reference potential. Then, the diaphragm 104 descends and the volume of the pressurized liquid chamber 203 expands, so that ink flows into the pressurized liquid chamber 203. Thereafter, the voltage applied to the laminated piezoelectric element 301 is increased, the laminated piezoelectric element 301 is extended in the laminating direction, the diaphragm 104 is deformed in the nozzle direction, and the volume / volume of the pressurized liquid chamber 203 is contracted.

  As a result, the recording liquid in the pressurized liquid chamber 203 is pressurized, and droplets of the recording liquid are ejected (jetted) from the nozzle 201. Then, the diaphragm 104 is restored to the initial position by returning the voltage applied to the laminated piezoelectric element 301 to the reference potential. Then, the pressurized liquid chamber 203 expands and negative pressure is generated. At this time, the recording liquid is filled into the pressurized liquid chamber 203 from the common liquid chamber 204. Then, after the vibration of the meniscus surface of the nozzle is attenuated and stabilized, the operation for the next droplet discharge is started.

  In order to achieve both high speed and high image quality related to image output, it is necessary to drive at a higher frequency to change the droplet amount in a wider range from small droplets to large droplets. Therefore, in the present embodiment, a drive waveform composed of a plurality of pulse signals is driven while selecting a pulse signal according to the droplet type, thereby enabling ejection of different droplet types.

  Next, an example of the configuration of the head drive control unit and the head driver will be described with reference to FIGS. The head drive control unit generates a drive waveform (common drive waveform) composed of a plurality of drive pulses (drive signals) within one print cycle, and outputs a 2-bit image corresponding to the print image. A data transfer unit that outputs data (gradation signals 0 and 1), a clock signal, a latch signal (LAT), and a control signal is provided.

  In FIG. 6, the control signal is a 2-bit signal for instructing opening / closing of the analog switch, which is the switch means of the head driver shown in FIG. 5, for each droplet, and is a waveform to be selected in accordance with the print cycle of the common drive waveform. The state transitions to H level (ON), and when not selected, the state transitions to L level (OFF). A signal for selecting a large drop (1, 1), a signal for selecting a medium drop (1,0), a small drop There is a signal (0, 1) for selecting, and a signal (0, 0) for selecting non-ejection.

  The head driver shown in FIG. 5 includes a shift register that receives a grayscale signal 0 and a clock signal that are serially transferred from the data transfer unit to the transfer clock (shift clock), and a register value of the shift register from the data transfer unit to the latch signal LAT. The latch circuit that latches the register value, the latch circuit that latches the register value of the shift register with the latch signal LAT from the data transfer unit, and the control signal from the data transfer unit based on the output value of the latch circuit and the output value of the latch circuit Selector for selecting and outputting to a level conversion circuit (level shifter), level shifter for level-converting the logic level voltage signal of this selector to a level at which the analog switch can operate, and ON / OFF at the output of the selector provided via the level shifter Analog switch that consists of analog switches that are turned off And a i (switch means).

  Each analog switch of the analog switch array is connected to a selection electrode (individual electrode) of an element of each actuator, and a common drive waveform is input from the drive waveform generation unit. Therefore, when the analog switch is turned on in accordance with the control signal selected based on the serially transferred image data (gradation data 0, 1), the required drive signal constituting the common drive waveform passes ( Selected) applied to the actuator element.

Next, the present embodiment will be described more specifically with reference to FIG.
FIG. 7 shows the electrode formation of the actuator 107. A metal film is formed on the outside of the actuator 107 by a sputtering method, and in this case, the electrode is made of an alloy material such as Ni—Ag or Ag—Pt. Of course, it is not limited to this. Further, as shown in FIG. 7, the ON resistance R of the driver IC decreases in order (R1>R2>R3>R4>R5> R6... R94>R95> R96), and the internal wiring resistance of the driver IC. r also decreases in order (r1>r2>r3>r4>r5> r6... r94>r95> r96). In addition, the capacitance of the actuator is designed to increase in order as the distance from the connection portion increases (C1 <C2 <C3 <C4 <C5 <C6... C94 << C95 <C96). By adjusting the above three values, the combined impedance of the circuit can be expressed by R + 1 / jωC, so that the combined impedance of the circuit can be set to a substantially constant value (all the same). With such a design, even the actuators arranged in a line can be adjusted so that there is no variation in ink ejection characteristics depending on the distance from the connecting portion. actually,
R1 + 1 / jωC1 = (R2 + r1) + 1 / jωC2 = (R96 + r1 + r2 + ... + r95) + 1 / jωC96
Is established.

  In order to provide a common electrode 303 pattern for providing a drive waveform connected to one end face side of the plurality of laminated piezoelectric elements 301 and an individual electrode 302 pattern for providing a selection signal connected to the other end face side of the plurality of piezoelectric elements, 3 chamfer A at the end. This separates the electrode into two.

  FIG. 8 shows an individual electrode 302 pattern for applying a selection signal connected to the other end face side of the plurality of laminated piezoelectric elements, and FIG. 9 shows a common electrode 303 pattern.

  As can be seen in FIG. 8, the electrodes are individually provided and become individual electrode 302 patterns for supplying a selection signal connected to the other end face side of the plurality of laminated piezoelectric elements, and signals necessary for driving the head are supplied from the FFC 109. The actuator 107 can be driven.

  Further, the common electrode 303 in FIG. 9 does not form the individual electrode 302 pattern, and a common film is also formed on the head base 108 side to be fixed, so the next chamfered actuator is fixed to the head base. When fixing, if the adhesive 304 is a conductive material, it is in a conductive state with the head base.

  Here, the head base 108 originally fixes the actuator 107, but by using a conductive material, it can be a loop through which the electric signal flows. By forming a loop other than the common electrode 303, the resistance can be reduced.

  In this case, SUS was used as the material for the head base. This serves the purpose of conduction in addition to the strength of the material.

  Although it is the adhesive agent 304, it is possible to use a nonelectroconductive thing in this case. This is because the sputtering method was used when forming the electrodes.

FIG. 10 shows the surface roughness of the electrode surface formed by sputtering.
From the measurement results of the surface roughness after electrode formation by this sputtering method, it can be confirmed that the sputter surface is not flat and the finish is very rough. A method is adopted in which the adhesive and the adhesive 304 for fixing the actuator and the head base are pressed and fixed to the surface. However, even if the adhesive is a non-conductive material due to the influence of the surface roughness, When the metal film becomes the needle electrode 401 and is crimped, the resulting common electrode 303 and the head base 108 are electrically connected. As a result, a loop is formed, and a reduction in resistance can be realized. As a result, the drive waveform supplied to the head does not deteriorate.

A proof that current actually flows through the head base will be described with reference to FIG.
In a droplet discharge head in which piezoelectric elements are arranged at high density, it is necessary to simultaneously drive a large number of piezoelectric elements to discharge a large number of ink droplets at the same time. There is a problem in that the amount of displacement of the liquid crystal becomes unstable and the droplet discharge characteristics deteriorate, and the applied voltage tends to be lower as the piezoelectric element is located farther from the connection portion to which the external wiring is connected. It is also clear by referring to the wiring in the head driver circuit of FIGS. For this reason, even with piezoelectric elements arranged in a row, there is a problem that the droplet discharge characteristics vary depending on the distance from the connection portion. In this case, the discharge droplet velocity Vj between the channels was measured. However, it can be seen that the speed is stable.

  In this case, the sputtering thickness of the metal film (gold) used for the electrode was set to 0.4 μA for cost reduction.

  As a result, a drive waveform with no deterioration was confirmed compared with the drive waveform of the droplet discharge head with the 0.8 μA metal film before the change. Since the metal film functions not only as an electrode but also as an anti-corrosion function for the electrode, it is impossible to form the film. However, the adhesive is formed by means of forming the film by sputtering and providing a conductive loop on the head base. Regardless of the conductive characteristics, the thickness of the metal film used for the electrode can be minimized.

  According to the embodiment of the present invention described above, the actuator element that applies pressure to the individual liquid chambers provided corresponding to the plurality of nozzles is selectively selected at a predetermined printing timing by the drive signal from the head drive circuit. A recording head of a droplet discharge device that drives and discharges ink droplets from corresponding nozzles to record on a recording medium, and is different from a conductive purpose, apart from a common electrode portion on the ground side of each actuator element A conductive loop is provided in the head component that fulfills the function, and the IC on-resistance for driving the actuators arranged in a row becomes smaller as the distance from the connection portion becomes smaller. And Therefore, there is no need for special additional wiring, and no additional parts are required, and the resistance value of the through-electrode is substantially reduced with only the existing head components, so even if many actuator elements are driven simultaneously. The droplet discharge characteristics are stabilized without causing a voltage drop.

  Further, according to the embodiment of the present invention, the actuator element that applies pressure to the individual liquid chambers provided corresponding to the plurality of nozzles is selectively driven by a drive signal from the head drive circuit at a predetermined print timing. A recording head of a droplet discharge apparatus that records on a recording medium by discharging ink droplets from the corresponding nozzles, and has a function different from the conductive purpose, apart from the common electrode portion on the ground side of each actuator element. A conductive loop is provided in the head component that achieves the above, and the combined impedances of the closed loop circuits for driving the actuators arranged in a line are all the same. Therefore, there is no need for special additional wiring, and no additional parts are required, and the resistance value of the through-electrode is substantially reduced with only the existing head components, so even if many actuator elements are driven simultaneously. The droplet discharge characteristics are stabilized without causing a voltage drop.

  Further, according to the embodiment of the present invention, the head component that forms a conductive loop separately from the common electrode portion on the ground side of each actuator element in the recording head of the droplet discharge apparatus is a head base that fixes the actuator element. It is characterized by that. Therefore, multiple functions can be diverted with one component.

  According to an embodiment of the present invention, a conductive material is used for a head base which is a head component for fixing an actuator element. Therefore, a conductive loop other than the common electrode can be secured, and low resistance can be realized.

  Further, according to the embodiment of the present invention, SUS is used as a material for the head base. Therefore, in addition to the stable stabilization of the actuator, which is the original purpose, a conductive loop other than the common electrode can be secured, and a reduction in resistance can be realized.

  In addition, according to the embodiment of the present invention, an adhesive is used for the actuator element and the fixing means of the head base, and is not affected by the conductivity of the adhesive used. Therefore, it is possible to securely fix the actuator and the head base.

  Further, according to the embodiment of the present invention, the common electrode portion on the ground side of each actuator element is formed by gold sputtering. Therefore, the actuator and the head base can be fixed with various adhesives.

  According to the embodiment of the present invention, the gold sputter film thickness of the common electrode portion on the ground side of each actuator element is 0.4 μm or less. Therefore, it is possible to minimize the thickness of the sputtered film using gold, which has been increasing in price in recent years, to obtain a cost reduction effect, and to reliably maintain the ejection stability of the droplet ejection head.

  Next, an example in which the above-described droplet discharge head of the present invention (recording head of the droplet discharge apparatus) is applied to an image forming apparatus will be described with reference to FIGS.

  FIG. 12 is a perspective explanatory view of the image forming apparatus including the liquid ejection head according to the present invention described in the above embodiment, as viewed from the front side. The image forming apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper loaded in the apparatus main body 1, and a sheet on which an image is recorded (formed) by being detachably mounted on the apparatus main body 1. A paper discharge tray 3 for stocking is provided. Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons and a display.

  The cartridge loading unit 4 includes a plurality of liquid cartridges 10k each containing liquid (ink) of different colors, for example, black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. 10c, 10m, and 10y (referred to as “liquid cartridge 10” when colors are not distinguished) can be inserted and loaded from the front side of the apparatus main body 1 toward the rear side, and the cartridge loading unit 4 has a front side. Has a front cover (cartridge cover) 6 that can be opened and closed when the liquid cartridge 10 is attached and detached.

  Next, the mechanism of this image forming apparatus will be described with reference to FIGS. FIG. 13 is a schematic configuration diagram for explaining the overall configuration of the mechanism unit, and FIG. 14 is a plan view for explaining a main part of the mechanism unit.

  A carriage 33 is slidably held in the main scanning direction by a main guide rod 31 and a sub guide rod 32 that are horizontally mounted on the left and right main side plates 21A and 21B constituting the frame 20, and a timing belt is held by a main scanning motor (not shown). Then, moving scanning is performed in the direction indicated by the arrow (carriage main scanning direction) in FIG.

  The carriage 33 has a liquid ejection head 34 (described in the above embodiment) having a plurality of nozzle rows that eject droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). The recording head of the droplet discharge device of the present invention is mounted with a plurality of nozzles (discharge ports) arranged in a direction crossing the main scanning direction and the droplet discharge direction facing downward.

  The liquid ejection head 34 can be used as a piezoelectric actuator such as a piezoelectric element provided as pressure generating means for generating pressure for ejecting droplets.

  In addition, the carriage 33 is equipped with a liquid tank 35 (which may be integrated) for each color for supplying each color liquid to each liquid ejection head 34. As described above, the liquid tanks 35 of the respective colors are supplementarily supplied with the liquids of the respective colors from the liquid cartridges 10 mounted on the cartridge loading unit 4 through the supply tubes 36 having the flexibility of the respective colors. The cartridge loading unit 4 is provided with a supply pump unit 24 that is a liquid feeding means for feeding the liquid in the liquid cartridge 10. The supply tube 36 is held on the front stay 29 by a holding member 37 in the middle.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  A guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressurization are provided to feed the paper 42 fed from the paper feeding unit to the lower side of the liquid discharge head 34. A pressing member 48 having a roller 49 and a conveying belt 51 serving as a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34 are provided.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. Further, a guide member 57 serving as a platen portion is disposed on the back side of the conveyance belt 51 so as to correspond to a printing area by the recording head 34.

  The transport belt 51 rotates in the belt transport direction of FIG. 14 when the transport roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the liquid discharge head 34, a separation claw 61 for separating the paper 42 from the transport belt 51, a paper discharge roller 62, and a paper discharge roller 63 are provided. In addition, a paper discharge tray 3 is provided below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 14, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the liquid ejection head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. ing.

  The maintenance and recovery mechanism 81 includes a cap member 82 for collectively capping the nozzles 341a of the liquid discharge head 34, a wiper blade 83 which is a blade member for wiping the nozzle surface, and a thickened liquid. An empty discharge receptacle 84 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording in order to be discharged is provided.

  Then, the waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 81, the liquid discharged to the cap 82, or the liquid attached to the wiper blade 83 and removed by the wiper cleaner 85, is ejected to the idle ejection receiver 94. The discharged ink is discharged and stored in a waste liquid tank (not shown).

  Further, as shown in FIG. 14, when the idle discharge is performed in the non-printing area on the other side in the scanning direction of the carriage 33 to discharge the liquid that does not contribute to the recording in order to discharge the thickened liquid during the recording. An empty discharge receiver 88 for receiving the liquid droplets is disposed, and the empty discharge receiver 88 includes an opening 89 along the nozzle row direction of the liquid discharge head 34.

  In the liquid discharge head recording apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheets 42 fed substantially vertically upward are guided by the guide 45, It is sandwiched between the counter roller 46 and conveyed, and further, the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control unit (not shown) to the charging roller 56, that is, an alternating voltage is applied and the conveying belt 51 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 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51. Therefore, by driving the liquid ejection head 34 according to the image signal while moving the carriage 33, the liquid droplets are ejected onto the stopped paper 42 to record one line, and the paper 42 is conveyed by a predetermined amount. Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  During printing (recording) standby, the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the cap member 82 capping the discharge surface 34a of the liquid discharge head 34 to keep the nozzle in a wet state, thereby drying the liquid. Prevents ejection failure due to In the state where the ejection surface 34a of the liquid ejection head 34 is capped by the cap member 82, the recording liquid is sucked from the nozzle by a suction pump (not shown) (referred to as “nozzle suction” or “head suction”) to increase the viscosity. Perform a recovery action to drain the liquid.

  Also, an idle discharge operation for discharging a liquid not related to the recording is performed before the start of recording or during the recording. As a result, the stable ejection performance of the recording head 34 is maintained.

  As described above, by applying the present invention, a high-quality liquid droplet ejection head can be manufactured at low cost, and the liquid droplet ejection head embodying the present invention is mounted in the image forming apparatus. Therefore, it is possible to provide a low-cost and high-quality image forming apparatus.

  Note that the image forming apparatus according to the present invention can also be applied to a printer, a facsimile machine, a copying machine, a multi-function machine thereof, and the like. Further, the present invention can also be applied to a droplet discharge head or a droplet discharge device that discharges a liquid other than ink, such as a DNA sample, a resist, or a pattern material, or an image forming apparatus that includes these.

  The embodiment of the present invention has been described above, but the present invention is not limited to the description of the embodiment, and various modifications can be made without departing from the scope of the invention.

  The present invention can be applied to various ink jet type liquid ejection heads and liquid droplet ejection apparatuses.

It is a component block diagram of the droplet discharge discharge head concerning this invention. It is a cross-sectional schematic diagram of the liquid chamber width direction of the droplet discharge head concerning this invention. It is a figure which shows the adhesion part of an actuator, a drive signal transmission part, and head base adhesion | attachment. It is a group diagram of the drive part of the droplet discharge head concerning this invention. It is a wiring diagram of a head drive control circuit. It is an example of the various signals for the head drive concerning this invention. It is a head drive circuit diagram concerning the present invention. It is a side view of an individual electrode. It is a side view of a common electrode. It is the figure which showed the roughness measurement result of the sputtering surface. It is a figure of the drop speed measurement result between each channel. FIG. 3 is a perspective explanatory view of an image forming apparatus including the liquid ejection head according to the present invention as viewed from the front side. FIG. 2 is a schematic configuration diagram illustrating an overall configuration of the mechanism unit of the image forming apparatus of the present invention. FIG. 3 is a plan view of a main part of a mechanism unit of the image forming apparatus of the present invention.

Explanation of symbols

101 Nozzle cover 102 Nozzle plate 103 Channel plate 104 Vibration plate 105 Head frame 106 FPC
107 Actuator (PZT)
108 Head base 109 FFC
DESCRIPTION OF SYMBOLS 201 Nozzle 202 Nozzle communication path 203 Pressurized liquid chamber 204 Common liquid chamber 205 Ink supply port 206 Head tank 207 Filter unit 301 Multilayer piezoelectric element 302 Individual electrode 303 Common electrode 304 Adhesive 305 Internal electrode 401 Needle electrode
a PZT chamfer

Claims (7)

Actuator elements that apply pressure to the individual liquid chambers provided corresponding to the plurality of nozzles are selectively driven by a drive signal from the head drive circuit at a predetermined printing timing, and ink droplets are ejected from the corresponding nozzles. And a recording head of a droplet discharge device for recording on a recording medium,
In addition to the common electrode portion on the ground side of each actuator element, a driving IC is provided for driving actuators arranged in a row, with a conductive loop provided by a head component that performs a function different from the purpose of conduction. A recording head of a liquid ejection apparatus, wherein the on-resistance decreases as the distance from the connection portion increases. Said head component to be separate from the conductive loop and the common electrode portion of the ground side of each actuator element, the recording head of the liquid ejecting apparatus according to claim 1, wherein the Oh Rukoto the head base for fixing the actuator element . Recording head of the liquid ejecting apparatus according to claim 2, characterized in Rukoto using a conductive material on the head base is before head component to fix the KIA actuator element. The recording head of the liquid discharge apparatus in claim 3 serial mounting, which comprises using a SUS head based materials. Recording head of the liquid ejecting apparatus according to the common electrode portions of the ground side of each actuator element to claim 1, wherein the film formation to Rukoto by sputtering of gold. 6. The recording head of a liquid ejection apparatus according to claim 5 , wherein the sputtered film thickness of the common electrode portion on the ground side of each actuator element is 0.4 [mu] m or less . An image forming apparatus comprising the recording head of the liquid ejection apparatus according to claim 1 .

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