JP2010120355A - Liquid discharge head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can reduce variation of droplet discharge properties between nozzles resulting from that displacement of piezoelectric element column in the end part is different from that of the other piezoelectric element columns in a liquid discharge head using a piezoelectric element member having a plurality of piezoelectric element columns. <P>SOLUTION: The image forming apparatus has a piezoelectric element member arranged with a plurality of piezoelectric element columns, and includes a second common drive waveform generation part 541B for generating a common drive waveform to be applied to a piezoelectric element column in the end part and a first common drive waveform generation part 541A for generating a common drive waveform to be applied to piezoelectric element columns other than the piezoelectric element column in the end part. A drive voltage to be applied to the piezoelectric element column in the end part is set higher than a drive voltage to be applied to the piezoelectric element columns other than the piezoelectric element column in the end part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid discharge head and an image forming apparatus including the liquid discharge head as a recording head.

  In general, as a printer / fax / copier or an image forming apparatus combining these functions, for example, a liquid ejection apparatus including a recording head composed of a liquid ejection head that ejects liquid droplets of a recording liquid (liquid) is used. While conveying a medium (hereinafter also referred to as “paper”, the material is not limited, and a recording medium, a recording medium, a transfer material, and recording paper are also used synonymously) In some cases, image formation (recording, printing, printing, and printing are also used synonymously) is made by adhering ink to a sheet.

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium. Further, the liquid ejection apparatus means an apparatus that ejects liquid from a liquid ejection head, and is not limited to an apparatus that performs image formation.

  As the liquid ejection head, a piezoelectric element is used as pressure generation means (actuator means) for generating pressure for pressurizing ink, which is liquid in the liquid chamber, and droplets are ejected by changing the volume / pressure in the liquid chamber. A piezoelectric head using a so-called piezoelectric actuator is known.

  For example, in Patent Document 1, a plurality of ink chambers are partitioned by partition walls made of a piezoelectric material, each drive electrode is provided with each drive electrode, a drive signal is applied to each drive electrode, and each partition wall is subjected to shear deformation. Ink is ejected from the ink chamber, the thickness of the outer wall of the ink chamber at both ends of the head is matched to the thickness of each partition wall, drive electrodes are provided on the outer wall, and the outer wall is sheared in the same manner as the inner partition wall. There is disclosed a head that is deformed to eject ink from an outer ink chamber as well as an inner ink chamber.

  Further, in Patent Document 2, in order to reduce variation in ejection characteristics between droplet ejection heads, the charging state of each piezoelectric element is analogized via an analog switch that individually drives each piezoelectric element during ink ejection. An image forming apparatus is described in which the combined impedance of switches is set according to the difference in time constant determined by the capacitance of the piezoelectric element, and the voltage waveform applied to each piezoelectric element is made uniform.

JP 2002-218902 A JP 2003-170588 A

  However, since the head disclosed in Patent Document 1 employs a drive method based on the share mode, the outer walls of the ink chambers at both ends are used to make the discharge characteristics of the discharge channels at both ends equal to the discharge characteristics of the discharge channels other than both ends. It is necessary to match the thickness of each partition wall with that of each partition wall and to provide drive electrodes on the outer wall, which causes a problem that the structure becomes complicated.

  Further, in the image forming apparatus of Patent Document 2, it is possible to reduce variations in droplet ejection characteristics among a plurality of heads, but it is not possible to reduce variations in droplet ejection characteristics of each nozzle in the same head. There is a problem.

  Further, as the liquid discharge head, for example, a plurality of columnar piezoelectric elements (piezoelectric element columns) formed by grooving a laminated piezoelectric element member at a predetermined pitch, and a plurality of piezoelectric element members arranged on a substrate are long. However, with such a head, it is difficult to make the displacement characteristics of the piezoelectric element column at the end of the piezoelectric element member the same as other than the end, and as a result, the droplet discharge characteristics may vary. There is.

  The present invention has been made in view of the above-described problems, and an object thereof is to reduce variations in droplet discharge characteristics between nozzles.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A plurality of nozzles for discharging droplets, a plurality of liquid chambers communicating with each nozzle, a diaphragm forming at least a part of a wall surface of the liquid chamber, and a piezoelectric element column connected to the diaphragm. A liquid ejection head having one or a plurality of piezoelectric element members arranged in a plurality at intervals;
And a means for applying a drive voltage higher than the drive voltage for the other piezoelectric element columns to the piezoelectric element columns at the end of the piezoelectric element member of the liquid discharge head.

The liquid discharge head according to the present invention includes:
A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
The width in the arrangement direction of the piezoelectric element columns at the end of the piezoelectric element member is wider than the width in the arrangement direction of the other piezoelectric element columns.

The liquid discharge head according to the present invention includes:
A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
The piezoelectric element column is connected to a convex portion provided on the diaphragm,
The width in the arrangement direction of the projections connected to the piezoelectric element column at the end of the piezoelectric element member or the width or arrangement in the arrangement direction of the projections connected to another piezoelectric element column in the direction orthogonal to the arrangement direction It was set as the structure wider than the width | variety of the direction orthogonal to a direction.

The liquid discharge head according to the present invention includes:
A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
Each liquid chamber is supplied with ink from a common liquid chamber via a supply path having a fluid resistance portion,
The fluid resistance value of the fluid resistance portion of the supply path to the liquid chamber corresponding to the piezoelectric element column at the end of the piezoelectric element member is that of the fluid resistance portion of the supply path to the liquid chamber corresponding to another piezoelectric element column. It was set as the structure larger than a fluid resistance value.

The liquid discharge head according to the present invention includes:
A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
The volume of the liquid chamber corresponding to the piezoelectric element column at the end of the piezoelectric element member is smaller than the volume of the liquid chamber corresponding to the other piezoelectric element column.

  In the liquid ejection head according to the present invention, a plurality of the piezoelectric element members may be arranged side by side.

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

  The image forming apparatus according to the present invention includes means for applying a drive voltage higher than the drive voltages for the other piezoelectric element columns to the piezoelectric element columns at the ends of the piezoelectric element members of the liquid ejection head. The variation in droplet discharge characteristics between nozzles in the same head can be reduced, and a high-quality image can be formed.

  According to the liquid ejection head of the present invention, the width of the piezoelectric element columns at the end of the piezoelectric element member is wider than the width of the other piezoelectric element columns in the arrangement direction, and the piezoelectric element columns are provided on the diaphragm. An array of convex portions connected to other piezoelectric element columns with a width in the arrangement direction of the convex portions connected to the piezoelectric element columns at the end of the piezoelectric element member or a width in a direction perpendicular to the arrangement direction. The width of the direction or the width wider than the direction perpendicular to the arrangement direction, each of the liquid chambers is supplied with ink from a common liquid chamber via a supply path having a fluid resistance portion, and the piezoelectric element at the end of the piezoelectric element member A structure in which the fluid resistance value of the fluid resistance portion of the supply path to the liquid chamber corresponding to the column is larger than the fluid resistance value of the fluid resistance portion of the supply path to the liquid chamber corresponding to the other piezoelectric element columns; The volume of the liquid chamber corresponding to the piezoelectric element column at the end is the volume of the liquid chamber corresponding to the other piezoelectric element column. Since the smaller structure than it is possible to reduce variations in droplet ejection characteristics among the nozzles in the same head.

  According to the image forming apparatus according to the present invention, since the liquid ejection head according to the present invention is provided, variation in droplet ejection characteristics can be reduced and a high-quality image can be formed.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is an explanatory plan view showing a schematic configuration of the image forming apparatus.
This image forming apparatus is a serial type ink jet recording apparatus, and a carriage 3 is slidably held by a main guide rod 1 horizontally mounted on left and right side plates (not shown) and a sub guide member (not shown). It moves and scans in the main scanning direction via a timing belt 8 passed between the driving pulley 6 and the driven pulley 7.

  The carriage 3 is provided with recording heads 4a and 4b composed of liquid ejection heads for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K) (when not distinguished). The “recording head 4” is arranged in a sub-scanning direction orthogonal to the main scanning direction, and the ink droplet ejection direction is directed downward.

  The recording head 4 has two nozzle rows 4n1 and 4n2, respectively. One nozzle row 4n1 of the recording head 4a receives black (K) droplets, and the other nozzle row 4n2 receives cyan (C) droplets. The one nozzle row 4n1 of the recording head 4b discharges magenta (M) droplets, and the other nozzle row 4n2 discharges yellow (Y) droplets. As the liquid discharge head constituting the recording head 4, a liquid discharge head provided with a piezoelectric actuator such as a piezoelectric element as pressure generating means for generating a pressure for discharging a droplet is used as will be described later.

  On the other hand, in order to transport the paper, a transport belt 12 is provided as a transport means for electrostatically attracting the paper and transporting the paper at a position facing the recording head 4. The conveyor belt 12 is an endless belt, and is configured to wrap around the conveyor roller 13 and the tension roller 14 so as to circulate in the belt conveyance direction (sub-scanning direction), and is not shown while being circulated. It is charged (charged) by the charging roller.

  The transport belt 12 may be a single-layer belt or a multi-layer (two or more layers) belt. In the case of a single-layer conveyor belt, it contacts the paper or charging roller, so the entire layer is formed of an insulating material. In the case of a transport belt having a multilayer structure, it is preferable that the side that contacts the paper or the charging roller is formed of an insulating layer, and the side that does not contact the paper or the charging roller is formed of a conductive layer.

  Further, the conveyance belt 12 rotates in the sub-scanning direction when the conveyance roller 13 is rotationally driven by the sub-scanning motor 16 via the timing belt 17 and the timing pulley 18.

  Further, a maintenance / recovery mechanism 21 that performs maintenance / recovery of the recording head 4 on the side of the conveyance belt 12 is disposed on one side of the carriage 3 in the main scanning direction, and the recording head 14 is disposed on the side of the conveyance belt 12 on the other side. The empty discharge receptacles 21 for performing empty discharge are respectively disposed. The maintenance / recovery mechanism 20 includes, for example, a cap member for capping the nozzle surface (surface on which the nozzles are formed) of the recording head 4, a wiper member for wiping the nozzle surface, and an empty discharge receiver for discharging liquid droplets that do not contribute to image formation. Etc.

  In addition, an encoder scale 23 having a predetermined pattern formed between both side plates along the main scanning direction of the carriage 13 is stretched, and the encoder 23 includes a transmissive photosensor that reads the pattern of the encoder scale 23 on the carriage 23. The encoder scale 23 and the encoder sensor 24 constitute a linear encoder (main scanning encoder) that detects the movement of the carriage 23.

  Further, a high-resolution code wheel 25 is attached to the shaft of the transport roller 13, and an encoder sensor 26 including a transmission type photosensor for detecting a pattern formed on the code wheel 25 is provided. 26 constitutes a rotary encoder (sub-scanning encoder) that detects the movement amount and movement position of the conveyor belt 12.

  In this image forming apparatus configured as described above, the sheet is fed from the sheet feeding tray (not shown) onto the charged conveying belt 12 and sucked, and the sheet is conveyed in the sub-scanning direction by the circular movement of the conveying belt 12. The Therefore, by driving the recording head 14 according to the image signal while moving the carriage 13 in the main scanning direction, ink droplets are ejected onto the stopped paper to record one line, and the paper is conveyed by a predetermined amount. After that, the next line is recorded. Upon receiving a recording end signal or a signal indicating that the trailing edge of the sheet has reached the recording area, the recording operation is terminated and the sheet is discharged to a discharge tray (not shown).

  Next, an example of the liquid discharge head constituting the recording head in the ink jet recording apparatus will be described with reference to FIGS. 2 is a cross-sectional explanatory view along the liquid chamber longitudinal direction (direction orthogonal to the liquid chamber arrangement direction) of the liquid discharge head, and FIG. 3 is a cross-section along the liquid chamber short direction (liquid chamber arrangement direction). 4 is an enlarged explanatory view of the main part of FIG. 2, and FIG. 5 is an enlarged explanatory view of the main part of FIG.

  The liquid discharge head 100 includes a flow path substrate (liquid chamber substrate) 101 formed of a SUS substrate, a vibration plate member 102 bonded to the lower surface of the flow path substrate 1, and a nozzle plate bonded to the upper surface of the flow path substrate 101. 103, and a liquid chamber (hereinafter referred to as a “pressurized liquid chamber” as an individual flow channel) through which a nozzle 104 that discharges droplets (liquid droplets) communicates is referred to as a pressure chamber, a pressure chamber, and a flow channel. 106), a fluid resistance unit 107 that also serves as a supply path for supplying ink (recording liquid) that is liquid to the pressurized liquid chamber 106, and a common supply of recording liquid to the plurality of pressurized liquid chambers 106. A liquid chamber 108 is formed. The common liquid chamber 108 is supplied with ink from a liquid tank (not shown) via a supply path.

  Here, the flow path substrate 101 is formed by bonding a restrictor plate 101A and a chamber plate 101B. The flow path substrate 101 is formed by etching the SUS substrate using an acidic etchant or machining such as punching (pressing), so that each pressurized liquid chamber 6, fluid resistance portion 7, common liquid chamber 8, etc. Each opening is formed. The fluid resistance portion 107 is formed by opening a portion of the restrictor plate 101A and not opening a portion of the chamber plate 101B.

  The diaphragm member 102 is bonded and bonded to the chamber plate 101 </ b> B constituting the flow path substrate 101. The diaphragm member 102 is, for example, a resin layer (resin member) obtained by directly applying (coating) a resin whose coefficient of linear expansion is larger than that of the metal member 121 to a metal member 121 such as a SUS substrate, and heating and solidifying the resin. The resin layer 122 forms a deformable portion (vibrating plate region) 102A which becomes the wall surface of the liquid chamber 106, and the vibrating plate region 102A is opposite to the liquid chamber 106. The metal member 121 is patterned by etching to form island-shaped protrusions (hereinafter also referred to as “island-shaped protrusions”) 102B that are connected to the piezoelectric element columns. In addition, the diaphragm member 102 may be formed by bonding a resin layer and a metal member with an adhesive, or formed by electroforming such as Ni.

  The nozzle plate 103 forms a large number of nozzles 104 having a diameter of 10 to 30 μm corresponding to the pressurized liquid chambers 106 and is adhesively bonded to the restrictor plate 101 </ b> A of the flow path substrate 101. The nozzle plate 103 may be made of a metal such as stainless steel or nickel, a resin such as a polyimide resin film, silicon, or a combination thereof. Further, a water repellent film is formed on the nozzle surface (surface in the ejection direction: ejection surface) by a known method such as a plating film or a water repellent coating in order to ensure water repellency with ink.

  A piezoelectric actuator 110 is disposed on the lower surface side (the surface opposite to the pressurized liquid chamber 106) of the diaphragm member 102. In this piezoelectric actuator 110, a plurality of piezoelectric element members 112 in which a plurality of piezoelectric element columns 111 are arranged are arranged on a substrate 114, and the piezoelectric element columns 111 are adhesively bonded to the island-shaped convex portions 102B of the diaphragm member 102. ing.

  The piezoelectric element member 112 is formed with a plurality of piezoelectric element columns 111 at a predetermined pitch via slit grooves 115 by performing slit processing (groove processing) without being divided, and two different piezoelectric elements. The interval 120 between the adjacent piezoelectric element columns 111 of the element member 112 is also set to be equal to the groove width of the slit groove 115.

  Here, a normal pitch configuration is adopted in which each piezoelectric element column 111 of the piezoelectric element member 112 is driven as a piezoelectric element column (driving piezoelectric element column), but every other piezoelectric element column (driving piezoelectric element) is driven. It is also possible to adopt a bi-pitch configuration used as a piezoelectric element column (non-driving piezoelectric element column) that is used as a column without being driven. Hereinafter, all the piezoelectric element columns 111 will be described as drive piezoelectric element columns.

  Here, as shown in FIG. 4, the piezoelectric element member 112 is composed of a lead zirconate titanate (PZT) piezoelectric layer 126 having a thickness of 10 to 50 μm / layer and a silver / thickness of several μm / layer. The internal electrode layers 127 and 128 made of palladium (AgPd) are alternately laminated, and the internal electrodes 127 and 128 are alternately connected to the individual electrodes 124 and the common electrode 125 which are end face electrodes (external electrodes) on the end faces, respectively. The wiring electrodes of the FPC 113 that is a power supply member are connected to the individual electrode 124 and the common electrode 125. Note that the common electrode 125 is configured such that the bottom surface of the piezoelectric element member 112 is wound around and pulled out to the individual electrode 124 side, and the FPC 113 is connected to the same surface of the piezoelectric element member 112.

  The diaphragm region 102A is displaced by the expansion and contraction of the piezoelectric element column 111 of the piezoelectric element member 112 whose piezoelectric constant is d33 (d33 indicates expansion / contraction perpendicular to the internal electrode surface (thickness direction)), thereby causing the liquid chamber 106 to move. It is designed to shrink and expand. When the drive signal is applied to the piezoelectric element column 111 and charging is performed, the piezoelectric element column 111 expands. When the electric charge charged to the piezoelectric element column 111 is discharged, the piezoelectric element column 111 contracts in the opposite direction.

  Further, a frame member 117 is joined around the diaphragm member 102 with an adhesive. A buffer chamber 118 adjacent to the common liquid chamber 108 is formed in the frame member 117 via a diaphragm portion 102 </ b> C as a deformable portion constituted by the resin layer 122 of the diaphragm member 102. The diaphragm portion 102 </ b> C forms wall surfaces of the common liquid chamber 108 and the buffer chamber 118. Note that the buffer chamber 118 communicates with the atmosphere via the communication path 119.

  In the liquid discharge head 100 configured in this way, for example, the piezoelectric element column 111 contracts by lowering the voltage applied to the piezoelectric element column 111 of the piezoelectric element member 112 from the reference potential Ve, and the diaphragm region of the diaphragm member 102 102A descends and the volume of the pressurized liquid chamber 106 expands, so that the ink flows into the pressurized liquid chamber 106, and then the voltage applied to the piezoelectric element column 111 is increased to move the drive piezoelectric element column 111 in the stacking direction. And the diaphragm region 102A is deformed in the direction of the nozzle 104 to contract the volume / volume of the pressurizing liquid chamber 106, whereby the ink in the pressurizing liquid chamber 106 is pressurized, and the recording liquid is supplied from the nozzle 104. Drops are ejected (jetted).

  Then, by returning the voltage applied to the piezoelectric element column 111 to the reference potential, the diaphragm region 102A is restored to the initial position, and the pressurized liquid chamber 106 expands to generate a negative pressure. At this time, the common liquid chamber The recording liquid is filled into the pressurized liquid chamber 106 from 108. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

Next, an outline of the control unit of the ink jet recording apparatus will be described with reference to the functional block diagram of FIG.
The control unit 500 controls the entire apparatus, and includes a CPU 501, a ROM 502, a RAM 503, a recording head control unit 504 that also serves as a common drive signal generation unit and a data transfer unit, a main scanning control unit 505, a sub scanning control unit 506, and a host I. / F507 and the like.

  Firmware for performing hardware control of this apparatus and drive waveform data for generating a common drive signal to be sent to the head drive unit 511 for driving the recording head 4 are stored in the ROM 502. The RAM 502 is used as various buffers and work memories and stores various data. The recording head control unit 504 includes a driving signal generation circuit that generates a common driving signal for the recording head 4, and sends the common driving signal together with the image data and the control signal to the head driving unit 511 mounted on the carriage 3 side.

  The main scanning control unit 505 detects the position of the carriage 3 in the main scanning direction based on the detection signal from the main scanning encoder 508, and controls the stop position of the carriage 3 by controlling the driving of the main scanning motor 5. The sub-scanning control unit 506 detects the rotation amount and rotation position of the conveying roller 13 based on the detection signal from the sub-scanning encoder 509, and controls the movement and stop position of the conveying belt 12 by controlling the driving of the sub-scanning motor 16. I do.

  The control unit 501 receives a print job (image data) transferred from a host (information processing apparatus such as a PC) 510 via the host I / F 507, and stores the received bitmap image data. Here, the image data is developed into bitmap data by the printer driver on the host 510 side and transferred to this recording apparatus. However, when bitmap development is performed on this recording apparatus side, the I / F 507 is used. The transfer data stored in the included reception buffer is read and analyzed, the analysis result (intermediate code data) is stored in a predetermined area of the RAM 503, and an image is stored using the font data stored in the ROM 502 from the stored analysis result. Dot pattern data to be output is generated and stored again in a different predetermined area of the RAM 503.

  Then, the carriage 3 on which the recording head 4 is mounted is moved to a required position on the paper by the main scanning control unit 505. The recording head control unit 504 interlocks with the position information of the carriage 3 obtained from the main scanning encoder 508, and performs image data stored in the RAM 503, common drive signals generated from the head drive data stored in the ROM 502, and gradation control. A control signal such as a signal is transferred to the head driving unit 511. The head driving unit 511 drives the actuator means (piezoelectric actuator 110) of the recording head 4 based on the data transferred from the recording head control unit 504, and ejects ink droplets.

Next, portions relating to transfer of printhead data and generation of a common drive waveform will be described with reference to the block diagram of FIG.
The recording head controller 504 generates a drive waveform (common drive signal) VcomA composed of a plurality of different drive pulses (drive signals) within one drive cycle as shown in FIG. And a drive waveform (common drive signal) VcomB composed of a plurality of different drive pulses (drive signals) within one drive cycle as shown in FIG. 8B. Then, a second common drive signal generation unit 541B that outputs to the head drive unit 511 and a data transfer unit 542 that transfers image data and control signals to the head drive unit 111 are provided.

  The common drive waveform VcomA is a piezoelectric element column 111 other than the piezoelectric element column 111 (referred to as “piezoelectric element column 111a” in FIG. 5) at the end of the piezoelectric element member 112 of the liquid ejection head 100. The common drive waveform VcomB is applied to the piezoelectric element column 111a at the end of the piezoelectric element member 112 of the liquid ejection head 100. Here, the voltage Vb (potential from the reference potential Ve) of the common drive waveform VcomB applied to the piezoelectric element column 111b at the end is the voltage Va (reference potential) of the common drive waveform VcomA applied to the other piezoelectric element column 111a. (Potential from Ve)) is set higher (larger).

  The data transfer unit 542 transfers image data corresponding to the print image as serial data SD1 and SD0 (denoted as SD [1: 0]), a shift clock signal SCK for transferring serial data SD1 and SD0, and a latch signal. Transfer LT. Further, the data transfer unit 142 transfers 4-bit gradation control signals MN3 to MN0 (denoted as MN [3: 0]) for selecting required drive signals of the common drive signals VcomA and VcomB.

  The gradation control signals MN3 to MN0 are 2-bit signals that instruct the opening and closing of the analog switch 555, which is a switch unit of the head driving unit 511, for each drop, and the required driving among the common driving signals VcomA and B. When the signal is selected in accordance with the printing cycle, the state transitions to the L level (OFF), and when the signal is not selected (when unnecessary drive signals are masked), the state transitions to the H level (ON).

  The head drive unit 511 latches the data of the shift register 551 by the shift register 551 that receives the transfer clock (shift clock) SCL and the serial data (image data in this embodiment) SD from the data transfer unit 542 and the latch signal LT. A latch circuit 552, a decoder 553 that decodes the image data SD and the gradation control signal MN and outputs the result, and a logic level voltage signal of the decoder 553 is converted to a level at which the analog switch 555 can operate. A level shifter 554 and an analog switch 155 that is turned on / off (opened / closed) by the output of the decoder 553 provided via the level shifter 554 are provided.

  The analog switch 555 is connected to the selection electrode (individual electrode) 124 of the piezoelectric element column 111 of the piezoelectric actuator 100 of the recording head 4 and receives the common drive signals VcomA and VcomB from the common drive signal generators 541A and 541B. . Accordingly, when the analog switch 555 is turned on according to the result of decoding the serially transferred image data and the gradation control signal MN by the decoder 553, the required drive signals constituting the common drive signals VcomA and VcomB pass. (Selected) and applied to the required piezoelectric element column 111 of the piezoelectric actuator 110.

Next, driving of the recording head (liquid discharge head) in the image forming apparatus configured as described above will be described with reference to FIG. Here, FIG. 9 shows a state in which a drive voltage is applied to every other piezoelectric element column of the piezoelectric element member.
First, as shown in FIG. 5 described above, the piezoelectric element member 112 is bonded and fixed to the substrate 114, but the portion that restrains the displacement of the active region of the piezoelectric element column 111b at the end (inactive region). ) 131 has a relatively small holding force compared to the portion (inactive region) 132 that restrains the displacement of the active region of the other piezoelectric element columns 111a other than the end portions, and therefore, the piezoelectric element column 111b and the piezoelectric element columns When the same drive voltage is applied to 111a and displaced, as shown in FIG. 9, the end of the piezoelectric element column 111b is also deformed in the channel direction (nozzle arrangement direction).

  As a result, as shown in FIG. 10, the amount of displacement in the stacking direction of the piezoelectric element column 111b at the end becomes smaller than the amount of displacement of the other piezoelectric element columns 111a other than the end (center portion in FIG. 10). As shown in FIG. 11, the droplet velocity of the droplets ejected from the nozzle corresponding to the piezoelectric element column 111b at the end is slower than the droplet velocity of the droplets ejected from the nozzle corresponding to the other piezoelectric element column 111a. Variation in droplet speed occurs between nozzles. The “drive channel” in FIG. 11 means a group of one nozzle, liquid chamber, and piezoelectric element column.

  Therefore, in this embodiment, as described with reference to FIG. 8, as shown in FIG. 12, the driving voltage Vb applied to the piezoelectric element column 111b at the end portion is changed from the driving voltage Va applied to the piezoelectric element column 111a other than the end portion. (The absolute value of the height of the potential from the reference potential Ve) is also set. As a result, the same displacement amount as that of the other piezoelectric element columns 111a can be obtained for the piezoelectric element columns 111b at the end, and the nozzles corresponding to the piezoelectric element columns 111b at the end are discharged from the nozzles as shown in FIG. The droplet speed of the droplets and the droplet speed of the droplets ejected from the nozzles corresponding to the other piezoelectric element columns 111a can be made substantially the same, and variations in the droplet speed between the nozzles are reduced.

  Thus, by providing means for applying a driving voltage higher than the driving voltage for the other piezoelectric element columns to the piezoelectric element column at the end of the piezoelectric element member of the liquid ejection head, the nozzles in the same head The variation in the droplet discharge characteristics can be reduced, and a high-quality image can be formed.

Next, a first embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 14 is an enlarged explanatory view of a main part of the same embodiment.
This liquid discharge head is the same as the liquid discharge head 100 of the first embodiment of the image forming apparatus, in the piezoelectric element column arrangement direction of the piezoelectric element column 111b at the end of the piezoelectric element member 112 (even in the nozzle arrangement direction and the liquid chamber arrangement direction). The width Wb of the piezoelectric element column 111a other than the end portion is wider than the width Wa.

  Thus, by making the column width Wb of the end piezoelectric element column 111b wider than the width Wa of the other piezoelectric element column 111a, the drive voltage applied to the end piezoelectric element column 111b and the other piezoelectric element column 111a is changed. Even if it is the same, the force generated in the piezoelectric element column 111b at the end increases, the force pushing up the diaphragm region 102A of the diaphragm 10 member 102 also increases, and the displacement amount of the piezoelectric element column 111b at the end changes to other piezoelectric elements. Even when the displacement is smaller than the displacement of the element column 111a, the droplet velocity discharged from the nozzle corresponding to the piezoelectric element column 111b at the end and the droplet discharged from the nozzle corresponding to the other piezoelectric element column 111a. Drop speed can be made substantially the same, and variation in drop speed between nozzles is reduced.

  Further, the drive waveforms applied to the respective piezoelectric element columns 111a and 111b can be made the same (for example, only the first common drive waveform generating unit 541A described above can be used), and the configuration of the drive control unit can be simplified. .

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 15 is an enlarged explanatory view of a main part of the same embodiment.
In the liquid discharge head 100 according to the embodiment of the image forming apparatus, the liquid discharge head includes the piezoelectric element column array of the island-shaped convex portions 102Bb of the vibration plate member 102 connected to the piezoelectric element column 111b at the end of the piezoelectric element member 112. The width wb in the direction is formed wider than the width wa in the piezoelectric element column arrangement direction of the island-shaped convex portions 102Ba of the diaphragm member 102 connected to the piezoelectric element columns 111a other than the end portions.

  In this way, the width wb of the island-shaped convex portion 102Bb connected to the piezoelectric element column 111b at the end in the piezoelectric element column arrangement direction is set to the piezoelectric of the island-shaped convex portion 102Ba connected to the piezoelectric element column 111a other than the end. By making it wider than the width wa in the element column arrangement direction, even when the displacement amount of the piezoelectric element column 111b at the end is smaller than the displacement amount of the other piezoelectric element column 111a, it corresponds to the piezoelectric element column 111b at the end. Since the width wb of the convex portion 102Bb is large, the excluded volume is reduced, and droplet ejection characteristics of droplets ejected from the nozzle corresponding to the piezoelectric element column 111b at the end and ejection from the nozzles corresponding to the other piezoelectric element columns 111a The droplet ejection characteristics of the droplets to be produced can be made substantially the same, and variations in droplet speed between nozzles are reduced.

Next, a third embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. 16 is an explanatory diagram of a main part in a direction orthogonal to the arrangement direction of the end piezoelectric element column portions of the embodiment, and FIG. 17 is a direction orthogonal to the arrangement direction of the piezoelectric element column portions other than the end portions of the embodiment. It is principal part explanatory drawing.
In the liquid discharge head 100 according to the embodiment of the image forming apparatus, the liquid discharge head includes the piezoelectric element column array of the island-shaped convex portions 102Bb of the vibration plate member 102 connected to the piezoelectric element column 111b at the end of the piezoelectric element member 112. The width (length) Lb in the direction orthogonal to the direction is set to the width (in the direction orthogonal to the piezoelectric element column arrangement direction of the island-shaped protrusions 102Ba of the diaphragm member 102 coupled to the piezoelectric element columns 111a other than the end portions ( The length is wider than La.

  In this way, the width wb of the island-shaped convex portion 102Bb connected to the piezoelectric element column 111b at the end in the piezoelectric element column arrangement direction is set to the piezoelectric of the island-shaped convex portion 102Ba connected to the piezoelectric element column 111a other than the end. By making it wider than the width wa in the element column arrangement direction, even when the displacement amount of the piezoelectric element column 111b at the end is smaller than the displacement amount of the other piezoelectric element column 111a, it corresponds to the piezoelectric element column 111b at the end. Since the width wb of the convex portion 102Bb is large, the excluded volume is reduced, and droplet ejection characteristics of droplets ejected from the nozzle corresponding to the piezoelectric element column 111b at the end and ejection from the nozzles corresponding to the other piezoelectric element columns 111a The droplet ejection characteristics of the droplets to be produced can be made substantially the same, and variations in droplet speed between nozzles are reduced.

Next, a fourth embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 18 is an explanatory plan view of the liquid chamber portion of the embodiment.
In the liquid discharge head 100 according to the embodiment of the image forming apparatus, the liquid discharge head includes a liquid chamber of the fluid resistance unit 107b serving as a supply path to the liquid chamber 106a corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112. The width W1 in the direction orthogonal to the arrangement direction is made narrower than the width W0 in the direction orthogonal to the liquid chamber arrangement direction of the fluid resistance portion 107a with respect to the liquid chamber 106b corresponding to the piezoelectric element column 111a other than the end portion, The fluid resistance value of the fluid resistance portion 107b serving as a supply path to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end of the element member 112 is the fluid resistance to the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end. It is larger than the fluid resistance value of the portion 107a.

  In this way, the fluid resistance value of the fluid resistance portion 107b with respect to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end is set to the fluid of the fluid resistance portion 107a with respect to the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end. By making it larger than the resistance value, even if the displacement amount of the piezoelectric element column 111b at the end is smaller than the displacement amount of the other piezoelectric element column 111a, it is discharged from the nozzle corresponding to the piezoelectric element column 111b at the end. Droplet discharge characteristics of the liquid droplets can be enhanced, and the liquid droplet discharge characteristics of the liquid droplets discharged from the nozzles corresponding to the piezoelectric element columns 111b at the end and the liquid discharged from the nozzles corresponding to the other piezoelectric element columns 111a The droplet ejection characteristics of the droplets can be made substantially the same, and variations in droplet speed between nozzles are reduced.

Next, a fifth embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 19 is an explanatory plan view of a liquid chamber portion of the same embodiment.
In this liquid discharge head, in the liquid discharge head 100 of the embodiment of the image forming apparatus, a resistance member 141 (141a, 141b) is disposed between the liquid chamber 106 and the common liquid chamber 108, and the fluid resistance portions 107a, 107b. The width in the liquid chamber arrangement direction of the resistance member 141b provided in the supply path to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112 corresponds to the other piezoelectric element columns 111a other than the end. The fluid resistance of the fluid resistance portion 107b serving as a supply path to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112 is wider than the width of the resistance member 141a provided in the supply path to the liquid chamber 106a. The value is made larger than the fluid resistance value of the fluid resistance portion 107a with respect to the liquid chamber 106a corresponding to the piezoelectric element column 111a other than the end portion.

  In this way, the fluid resistance value of the fluid resistance portion 107b with respect to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end is set to the fluid of the fluid resistance portion 107a with respect to the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end. By making it larger than the resistance value, even if the displacement amount of the piezoelectric element column 111b at the end is smaller than the displacement amount of the other piezoelectric element column 111a, it is discharged from the nozzle corresponding to the piezoelectric element column 111b at the end. Droplet discharge characteristics of the liquid droplets can be enhanced, and the liquid droplet discharge characteristics of the liquid droplets discharged from the nozzles corresponding to the piezoelectric element columns 111b at the end and the liquid discharged from the nozzles corresponding to the other piezoelectric element columns 111a The droplet ejection characteristics of the droplets can be made substantially the same, and variations in droplet speed between nozzles are reduced.

Next, a sixth embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. 20 is an explanatory diagram of a main part in a direction orthogonal to the arrangement direction of the end piezoelectric element column portions of the embodiment, and FIG. 21 is a direction orthogonal to the arrangement direction of the piezoelectric element column portions other than the end portions of the embodiment. It is principal part explanatory drawing.
In the liquid discharge head 100 according to the embodiment of the image forming apparatus, the liquid discharge head includes a liquid chamber of the fluid resistance unit 107b serving as a supply path to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112. The width (length) L1 in the direction orthogonal to the arrangement direction is the width (length) in the direction orthogonal to the liquid chamber arrangement direction of the fluid resistance portion 107a with respect to the liquid chamber 106a corresponding to the piezoelectric element column 111a other than the end portion. The fluid resistance value of the fluid resistance portion 107b serving as a supply path to the liquid chamber 106 corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112 is set to be longer than L0 (the width in the liquid chamber arrangement direction is the same). It is larger than the fluid resistance value of the fluid resistance portion 107a with respect to the liquid chamber 106 corresponding to the piezoelectric element column 111a other than the portion.

  In this way, the fluid resistance value of the fluid resistance portion 107b with respect to the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end is set to the fluid of the fluid resistance portion 107a with respect to the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end. By making it larger than the resistance value, even if the displacement amount of the piezoelectric element column 111b at the end is smaller than the displacement amount of the other piezoelectric element column 111a, it is discharged from the nozzle corresponding to the piezoelectric element column 111b at the end. Droplet discharge characteristics of the liquid droplets can be enhanced, and the liquid droplet discharge characteristics of the liquid droplets discharged from the nozzles corresponding to the piezoelectric element columns 111b at the end and the liquid discharged from the nozzles corresponding to the other piezoelectric element columns 111a The droplet ejection characteristics of the droplets can be made substantially the same, and variations in droplet speed between nozzles are reduced.

Next, a seventh embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. Note that FIG. 22 is an explanatory diagram of a main part in a direction orthogonal to the arrangement direction of the end piezoelectric element column portions of the embodiment, and FIG. 23 is a direction orthogonal to the arrangement direction of the piezoelectric element column portions other than the end portions of the embodiment. It is principal part explanatory drawing.
In the liquid discharge head 100 according to the embodiment of the image forming apparatus, the liquid discharge head has a width in a direction perpendicular to the liquid chamber arrangement direction of the liquid chamber 106 b corresponding to the piezoelectric element column 111 b at the end of the piezoelectric element member 112 ( The length L11 is made shorter than the width (length) L10 in the direction orthogonal to the liquid chamber arrangement direction of the liquid chamber 106a corresponding to the piezoelectric element column 111a other than the end (width in the liquid chamber arrangement direction). The volume of the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end of the piezoelectric element member 112 is smaller than the volume of the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end.

  In this way, the volume of the liquid chamber 106b corresponding to the piezoelectric element column 111b at the end is made smaller than the volume of the liquid chamber 106a corresponding to the other piezoelectric element column 111a other than the end, so that the piezoelectric element at the end Even when the displacement amount of the column 111b is smaller than the displacement amount of the other piezoelectric element column 111a, the droplet ejection characteristics of the droplets ejected from the nozzle corresponding to the piezoelectric element column 111b at the end can be improved. The droplet ejection characteristics of the droplets ejected from the nozzle corresponding to the piezoelectric element column 111b of the part and the droplet ejection characteristics of the droplets ejected from the nozzle corresponding to the other piezoelectric element column 111a can be made substantially the same. , Variation in droplet speed between nozzles is reduced.

Next, another example of the image forming apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 24 is a schematic configuration diagram of the entire mechanism unit of the apparatus.
This image forming apparatus is a line type image forming apparatus, has an image forming unit 202 and the like inside the apparatus main body 201, and can supply a large number of recording media (sheets) 203 below the apparatus main body 201. A paper tray 204 is provided, the paper 203 fed from the paper feed tray 204 is taken in, a required image is recorded by the image forming unit 202 while the paper 203 is being transported by the transport mechanism 205, and then the side of the apparatus main body 201. The paper 203 is discharged to a paper discharge tray 206 attached to the printer.

  In addition, a duplex unit 207 that can be attached to and detached from the apparatus main body 201 is provided, and when performing duplex printing, the sheet 203 is taken into the duplex unit 207 while being transported in the reverse direction by the transport mechanism 205 after one-side (front) printing is completed. Then, the other side (back side) is sent to the transport mechanism 205 again as the printable side, and the sheet 203 is discharged to the discharge tray 206 after the other side (back side) printing is completed.

  Here, the image forming unit 202, for example, ejects liquid droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y), and is a full line type of four liquids according to the present invention. The recording heads 211k, 211c, 211m, and 211y (which are referred to as “recording heads 211” when the colors are not distinguished) are configured by ejection heads, and each recording head 211 has a nozzle surface on which nozzles for ejecting droplets are formed downward. The head holder 213 is attached.

  Further, maintenance recovery mechanisms 212k, 212c, 212m, and 212y for maintaining and recovering the head performance corresponding to each recording head 211 are provided (referred to as “maintenance recovery mechanism 212” when colors are not distinguished), and purge processing, During the head performance maintenance operation such as wiping processing, the recording head 211 and the maintenance / recovery mechanism 212 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 212 faces the nozzle surface of the recording head 211.

  Here, the recording head 211 is arranged to eject droplets of each color in the order of yellow, magenta, cyan, and black from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this. Further, as the line type head, one or a plurality of heads provided with a plurality of nozzle rows for discharging droplets of each color at a predetermined interval can be used, and a head and an ink cartridge for supplying ink to the head are integrated. Or a separate body.

  The sheets 203 in the sheet feeding tray 204 are separated one by one by a sheet feeding roller (half-moon roller) 221 and a separation pad (not shown) and fed into the apparatus main body 201, and are registered along the guide surface 223 a of the conveyance guide member 223. 225 and the conveying belt 233, and are sent to the conveying belt 233 of the conveying mechanism 205 via the guide member 226 at a predetermined timing.

  In addition, a guide surface 223 b that guides the sheet 203 sent out from the duplex unit 207 is also formed on the transport guide member 223. Further, a guide member 227 for guiding the sheet 203 returned from the transport mechanism 205 during duplex printing to the duplex unit 207 is also provided.

  The transport mechanism 205 includes an endless transport belt 233 that is stretched between a transport roller 231 that is a driving roller and a driven roller 232, a charging roller 234 that charges the transport belt 233, and an image forming unit 202. A platen member 235 that maintains the flatness of the conveying belt 233 at the opposite portion, a pressing roller 236 that presses the paper 203 fed from the conveying belt 233 against the conveying roller 231, and other recording liquid that is not shown, but adheres to the conveying belt 233. It has a cleaning roller made of a porous material or the like, which is a cleaning means for removing (ink).

  A paper discharge roller 238 and a spur 239 for sending the paper 203 on which an image is recorded to the paper discharge tray 206 are provided on the downstream side of the transport mechanism 205.

  In the image forming apparatus configured as described above, the transport belt 233 rotates in the direction indicated by the arrow, and is positively charged by coming into contact with the charging roller 334 to which a high potential applied voltage is applied. In this case, the charging belt 233 is charged at a predetermined charging pitch by switching the polarity of the charging voltage of the charging roller 234 at a predetermined time interval.

  Here, when the sheet 203 is fed onto the conveying belt 233 charged to this high potential, the inside of the sheet 203 is in a polarized state, and the charge opposite in polarity to the charge on the conveying belt 233 is conveyed to the conveying belt 233 of the sheet 203. The charge on the transport belt 233 and the charge on the transported sheet 203 are electrostatically attracted to each other, and the sheet 203 is electrostatically attracted to the transport belt 233. Is done. In this way, the sheet 203 strongly adsorbed to the conveyor belt 233 is calibrated for warpage and unevenness, and a highly flat surface is formed.

  Then, the paper 203 is moved around the conveyor belt 233 and droplets are ejected from the recording head 211, whereby a required image is formed on the paper 203, and the paper 203 on which the image is recorded is discharged to the paper discharge roller 238. Is discharged to the discharge tray 206.

  As described above, since the image forming apparatus includes the recording head including the liquid discharge head according to the present invention, variation in droplet discharge characteristics can be reduced, and a high-quality image can be formed at high speed. .

  The liquid discharge head according to the present invention can also be applied to a serial type image forming apparatus as described with reference to FIG. Further, the present invention can be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.

1 is a plan view illustrating a schematic configuration of an example of an image forming apparatus according to the present invention. FIG. 5 is a cross-sectional explanatory view along a liquid chamber longitudinal direction (a direction orthogonal to a liquid chamber arrangement direction) illustrating an example of a liquid discharge head. FIG. 5 is a cross-sectional explanatory view along the liquid chamber short direction (liquid chamber arrangement direction). FIG. 3 is an enlarged explanatory view of the main part of FIG. 2. FIG. 4 is an enlarged explanatory view of the main part of FIG. 3. It is a functional block diagram which shows the outline | summary of a control part. FIG. 6 is a block diagram for explaining portions related to transfer of printhead data and generation of a common drive waveform. It is explanatory drawing with which it uses for description of a drive waveform. It is explanatory drawing with which description of the example when the same drive voltage is applied to the piezoelectric element column of an edge part and the piezoelectric element column of a center part is provided. It is explanatory drawing similarly used for description of displacement amount. It is explanatory drawing with which it uses for description of a droplet discharge speed similarly. It is explanatory drawing with which it uses for description of the drive waveform of the embodiment. It is explanatory drawing with which it uses for description of the droplet discharge speed of the same embodiment. FIG. 3 is an enlarged explanatory view of a main part of the first embodiment of the liquid ejection head according to the present invention. FIG. 6 is an enlarged explanatory view of a main part of a second embodiment of the liquid ejection head according to the present invention. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of the edge part piezoelectric element pillar part of 3rd Embodiment of the liquid discharge head which concerns on this invention. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of piezoelectric element pillar parts other than the edge part of the embodiment. It is a plane explanatory view of the liquid chamber part of a 4th embodiment of the liquid discharge head concerning the present invention. It is a plane explanatory view of a liquid chamber part of a 5th embodiment of a liquid discharge head concerning the present invention. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of the edge part piezoelectric element column part of 6th Embodiment of the liquid discharge head which concerns on this invention. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of piezoelectric element pillar parts other than the edge part of the embodiment. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of the edge part piezoelectric element pillar part of 7th Embodiment of the liquid discharge head which concerns on this invention. It is principal part explanatory drawing of the direction orthogonal to the arrangement direction of piezoelectric element pillar parts other than the edge part of the embodiment. It is a schematic block diagram of the whole mechanism part which shows the other example of the image forming apparatus which concerns on this invention provided with the liquid discharge head which concerns on this invention.

Explanation of symbols

3. Carriage 4a, 4b ... Recording head (liquid discharge head)
DESCRIPTION OF SYMBOLS 100 ... Liquid discharge head 101 ... Flow path board | substrate 102 ... Vibration board member 103 ... Nozzle plate 104 ... Nozzle 106 ... Pressurizing liquid chamber 107 ... Fluid resistance part 110 ... Piezoelectric actuator 111 ... Piezoelectric element column 111a ... Piezoelectric element other than an edge part Column 111b ... Piezoelectric element column at end 112 ... Piezoelectric element member 511 ... Head drive unit 541A ... First common drive waveform generation unit 541B ... Second common drive waveform generation unit 211k, 211c, 211m, 211y ... Recording head (liquid ejection head)

Claims (7)

A plurality of nozzles for discharging droplets, a plurality of liquid chambers communicating with each nozzle, a diaphragm forming at least a part of a wall surface of the liquid chamber, and a piezoelectric element column connected to the diaphragm. A liquid ejection head having one or a plurality of piezoelectric element members arranged in a plurality at intervals;
An image forming apparatus comprising: means for applying a driving voltage higher than a driving voltage for another piezoelectric element column to a piezoelectric element column at an end of the piezoelectric element member of the liquid discharge head. A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
The liquid discharge head according to claim 1, wherein the width of the piezoelectric element columns at the end of the piezoelectric element member is wider than the width of the other piezoelectric element columns in the arrangement direction. A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
The piezoelectric element column is connected to a convex portion provided on the diaphragm,
The width in the arrangement direction of the projections connected to the piezoelectric element column at the end of the piezoelectric element member or the width or arrangement in the arrangement direction of the projections connected to another piezoelectric element column in the direction orthogonal to the arrangement direction A liquid discharge head characterized by being wider than a width in a direction orthogonal to the direction. A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
Each liquid chamber is supplied with ink from a common liquid chamber via a supply path having a fluid resistance portion,
The fluid resistance value of the fluid resistance portion of the supply path to the liquid chamber corresponding to the piezoelectric element column at the end of the piezoelectric element member is that of the fluid resistance portion of the supply path to the liquid chamber corresponding to another piezoelectric element column. A liquid discharge head characterized by being larger than a fluid resistance value. A plurality of nozzles that discharge droplets, a plurality of liquid chambers that communicate with each nozzle, a diaphragm that forms at least a part of a wall surface of the liquid chamber, and a plurality of piezoelectric element columns are arranged at predetermined intervals. A piezoelectric element member,
A droplet discharge head, wherein a volume of the liquid chamber corresponding to a piezoelectric element column at an end of the piezoelectric element member is smaller than a volume of the liquid chamber corresponding to another piezoelectric element column.   6. The liquid discharge head according to claim 2, wherein a plurality of the piezoelectric element members are arranged side by side.   An image forming apparatus comprising the liquid discharge head according to claim 2.

Images