In-head-module circuit, liquid discharge head, liquid discharge unit, liquid discharge apparatus, and image forming apparatus

Abstract

To provide an in-head-module circuit, a liquid discharge head, a liquid discharge unit, a liquid discharge apparatus, and an image forming apparatus capable of inhibiting the size and the cost of the image forming apparatus from increasing due to enlargement of the drive circuit built in the liquid discharge head.SOLUTION: An in-head-module circuit according to the present invention comprises: waveform-selection control circuits configured to select a drive waveform to be applied to the piezoelectric elements of nozzles included in the liquid discharge heads; drive-waveform generator circuits mounted at positions of the piezoelectric elements of nozzles at both ends of the liquid discharge heads in parallel to the waveform-selection control circuits, and configured to generate the drive waveform; and memory circuits corresponding to the drive-waveform generator circuits, and configured to store a correction voltage value of the drive waveform.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a circuit within a head module, a liquid ejection head, a liquid ejection unit, a liquid ejection apparatus, and an image forming apparatus. [Background technology]

[0002] A liquid ejection head has a characteristic that the ejection speed of droplets (liquid) changes depending on the nozzle position. To suppress this change in ejection speed, there is a technique for changing the drive voltage and drive waveform of the liquid ejection head (see Patent Document 1).

[0003] In addition, when forming an image using multiple liquid ejection heads, it is known that the change in ejection speed at the joints at the ends of the liquid ejection heads is particularly large, resulting in deterioration of the image. Conventionally, in order to suppress the difference in ejection speed at the joints at the ends of the liquid ejection heads, a method has been known in which a drive circuit corresponding to each individual nozzle is installed and the ejection speed of any individual nozzle is corrected. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above technology, a drive circuit is provided for every nozzle in the liquid ejection head, which requires the drive circuit built into the liquid ejection head to be large in scale and a cooling mechanism to be provided, resulting in a significant increase in head size and cost.

[0005] The present invention has been made in consideration of the above, and aims to provide a circuit within a head module, a liquid ejection head, a liquid ejection unit, a liquid ejection device, and an image forming apparatus that are capable of suppressing increases in size and cost due to the large scale of the driving circuit built into the liquid ejection head. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a waveform selection control circuit that selects a drive waveform for a piezoelectric element of a nozzle of a liquid ejection head, a drive waveform generation circuit that is mounted in parallel with the waveform selection control circuit at the position of the piezoelectric element of the nozzle at both ends of the liquid ejection head and generates the drive waveform, and a memory circuit that corresponds to the drive waveform generation circuit and stores a correction voltage value for the drive waveform. Effect of the Invention

[0007] According to the present invention, it is possible to suppress an increase in size and cost due to an increase in the scale of a drive circuit built into a liquid ejection head. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining an example of a cross section along the longitudinal direction of a liquid chamber of a recording head according to a first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining an example of a cross section along the short side direction of a liquid chamber of the recording head according to the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining an example of a head driver of the inkjet head according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram illustrating the overall configuration of the mechanism of the image forming apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a plan view illustrating an example of a main part of a mechanism unit included in the image forming apparatus according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view illustrating another example of the configuration of the image forming apparatus according to the first embodiment. [Figure 7] FIG. 7 is a top view of the image forming apparatus according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining an example of the configuration of a drive circuit for a piezoelectric element in the recording head of the image forming apparatus according to the first embodiment. [Figure 9]FIG. 9 is a diagram for explaining an example of a correction process for the dot positions corresponding to the nozzle positions of the image forming apparatus according to the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining an example of a correction process for the dot positions corresponding to the nozzle positions of the image forming apparatus according to the first embodiment. [Figure 11] FIG. 11 is a diagram for explaining an example of another circuit configuration according to the second embodiment. In FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a head module internal circuit, a liquid ejection head, a liquid ejection unit, a liquid ejection apparatus, and an image forming apparatus will be described in detail with reference to the accompanying drawings.

[0010] (First embodiment) Fig. 1 is a diagram for explaining an example of a cross section along the longitudinal direction of a liquid chamber of a recording head according to a first embodiment. Fig. 2 is a diagram for explaining an example of a cross section along the lateral direction of a liquid chamber of a recording head according to a first embodiment.

[0011] The recording head (e.g., inkjet head) according to the present embodiment is an example of a liquid ejection head, and includes a frame 1, a flow path plate 2, a nozzle plate 3, a vibration plate 6, a piezoelectric element X, a base 4, and the like. The frame 1 forms an engraving that becomes an ink supply port and a common liquid chamber 1-2. The flow path plate 2 forms an engraving that becomes a fluid resistance portion 2-1 and a pressurized liquid chamber 2-2, and a communication port 2-3 that communicates with a nozzle 3-1. The nozzle plate 3 forms a nozzle 3-1. The vibration plate 6 has a convex portion 6-1, a diaphragm portion 6-2, and an ink inlet 6-3. A piezoelectric element (e.g., a laminated piezoelectric element) X is bonded to the vibration plate 6 via an FPC 7. The base 4 fixes the piezoelectric element X. The piezoelectric element X is an example of a piezoelectric element that is driven by application of a drive waveform and ejects liquid from the nozzle 3-1.

[0012] The base 4 is made of barium titanate ceramic, and has two rows of piezoelectric elements X arranged and bonded to it. The piezoelectric elements X are made by alternately laminating piezoelectric layers 5-1 of lead zirconate titanate (PZT) with a thickness of 10 to 50 μm per layer and internal electrodes 5-2 of silver-palladium (AgPd) with a thickness of several μm per layer. The internal electrodes 5-2 are connected to individual electrodes 5-3 at both ends.

[0013] The piezoelectric element X is divided into comb-like pieces by half-cut dicing, and each piece is used as a driving part 5-5 and a supporting part 5-6 (non-driving part). The piezoelectric element X is formed by alternately laminating piezoelectric layers 5-1 of lead zirconate titanate (PZT) with a thickness of 10 to 50 μm per layer and internal electrodes 5-2 of silver-palladium (AgPd) with a thickness of several μm per layer, and the internal electrodes 5-2 are alternately electrically connected to individual electrodes 5-3 and common electrodes 5-4, which are end surface electrodes (external electrodes) on the end surfaces.

[0014] The inkjet head according to this embodiment is configured to use a piezoelectric element X in the d33 type, which is a displacement in the thickness direction, and the pressurized liquid chamber 2-2 is contracted and expanded by the expansion and contraction of the piezoelectric element X. The piezoelectric element X expands when a drive signal is applied and charging is performed, and contracts in the opposite direction when the charge stored in the piezoelectric element X is discharged.

[0015] An FPC 7 is soldered to the individual electrodes 5-3 of the drive unit 5-5. The common electrode 5-4 is provided with an electrode layer at the end of the piezoelectric element X, which is then twisted around and joined to the Gnd electrode of the FPC 7. A driver IC is mounted on the FPC 8, which controls the application of a drive voltage to the drive unit 5-5.

[0016] The diaphragm 6 is made of a thin film diaphragm portion 6-2, an island-shaped protrusion (island portion) 6-1 which is bonded to the piezoelectric element X which becomes the driving portion 5-5 formed in the center of the diaphragm portion 6-2, a thick film portion including a beam which is bonded to the support portion, and an opening which becomes the ink inlet 6-3, which are formed by stacking two layers of Ni plating film by electroforming.

[0017] The flow path plate 2 is made of a silicon single crystal substrate, and is patterned by etching to form the fluid resistance portion 2-1, the pressurized liquid chamber 2-2, the engraved portions that will become the communication port 2-3, and the through-holes that will become the communication port 2-3 at the positions corresponding to the nozzles 3-1. The portions that remain after etching become the partition walls 2-4 of the pressurized liquid chamber 2-2.

[0018] The nozzle plate 3 is made of a metal material, for example, a Ni plating film formed by electroforming, and has a large number of nozzles 3-1, which are fine ejection openings for ejecting ink droplets. The internal shape (inner shape) of the nozzles 3-1 is formed in a horn shape (it may be an approximately cylindrical shape or an approximately truncated cone shape).

[0019] A water-repellent layer is provided on the ink ejection surface (the nozzle surface side) of the nozzle plate 3. By providing a water-repellent film selected according to the ink properties, such as PTFE-Ni eutectoid plating, electrochemical coating of fluororesin, deposition coating of volatile fluororesin (e.g., pitch fluoride), or baking after solvent application of silicone resin or fluororesin, the ink droplet shape and flight characteristics are stabilized, and high-quality images can be obtained.

[0020] The frame 1, which forms the ink supply port and the carving that becomes the common liquid chamber 1-2, is made by resin molding.

[0021] In the inkjet head thus constructed, a driving waveform (e.g., a pulse voltage of 10 to 50 V) is applied to the driving section 5-5 in response to a recording signal, causing a displacement in the lamination direction in the driving section 5-5, pressurizing the pressurized liquid chamber 2-2 through the nozzle plate 3, increasing the pressure, and ejecting ink droplets from the nozzle 3-1. After that, with the end of ink droplet ejection, the ink pressure in the pressurized liquid chamber 2-2 decreases, and negative pressure is generated in the pressurized liquid chamber 2-2 due to the inertia of the ink flow and the discharge process of the driving pulse, and the ink transfers to the ink filling process. At this time, the ink supplied from the ink tank flows into the common liquid chamber 1-2, passes from the common liquid chamber 1-2 through the ink inlet 6-3, the communication port 2-3, and the fluid resistance section 2-1, and is filled in the pressurized liquid chamber 2-2. The fluid resistance section 2-1 is effective in attenuating residual pressure vibration after ejection, but it also acts as a resistance against refilling due to surface tension. By appropriately selecting the fluid resistance portion, it is possible to achieve a balance between the attenuation of the residual pressure and the refill time, and to shorten the time (drive cycle) until the next ink droplet ejection operation.

[0022] 3 is a diagram for explaining an example of a head driver of an inkjet head according to the first embodiment. In this embodiment, the head driver of the inkjet head has a waveform generating circuit 902 and a head module (Md) internal circuit 910. The waveform generating circuit 902 generates and outputs a driving waveform composed of a plurality of driving pulses (driving signals) within one printing cycle during image formation. The head Md internal circuit 910 receives input of 3-bit image data (e.g., gradation signal: 0, 1, 2) corresponding to the print image, a clock signal, and a latch signal (LAT).

[0023] The head module internal circuit 910 has a shift register 910a, a latch circuit 910b, and an analog switch (ASW) Y. The shift register 910a inputs image data and waveform data by a transfer clock (clock signal) and serial communication data from a data transfer unit. The latch circuit 910b latches each register value (image data, waveform data) of the shift register 910a by a latch signal. The analog switch Y selects a drive signal according to the gradation data (image data) and applies it to the piezoelectric element X.

[0024] Next, an example of a serial image forming apparatus including a liquid ejection device equipped with a liquid ejection head (inkjet head) according to the present embodiment will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a schematic diagram illustrating the overall configuration of a mechanism of the image forming apparatus according to the first embodiment. Fig. 5 is a plan view illustrating an example of a main part of the mechanism of the image forming apparatus according to the first embodiment.

[0025] The image forming apparatus according to this embodiment is a serial type image forming apparatus, in which a carriage 233 is held slidably in the main scanning direction by main and sub guide rods 231, 232, which are guide members horizontally mounted on left and right side plates 221A, 221B, and is moved and scanned in the direction indicated by the arrow (the carriage main scanning direction) via a timing belt by a main scanning motor.

[0026] On this carriage 233, recording heads 234a, 234b (when no distinction is made, they are referred to as recording heads 234) which are an example of a liquid ejection head that ejects ink droplets (an example of liquid, droplets) of each color of yellow (Y), cyan (C), magenta (M), and black (K) are mounted with a nozzle row consisting of multiple nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ink droplet ejection direction facing downward.

[0027] Each of the recording heads 234 has two nozzle rows, one of which (nozzle 3-1) in recording head 234a ejects black (K) droplets, the other nozzle row ejects cyan (C) droplets, and one of which in recording head 234b ejects magenta (M) droplets, the other nozzle row ejects yellow (Y) droplets. The carriage 233 is also equipped with head tanks 235a and 235b (when no distinction is made, they are referred to as head tanks 35) for supplying ink of each color corresponding to the nozzle rows of the recording head 234.

[0028] The head tank 235 is replenished with ink of each color from ink cartridges 210k, 210c, 210m, and 210y of each color through supply tubes 236 of each color. On the other hand, as a paper feed section for feeding paper 242 loaded on a paper loading section (pressure plate) 241 of the paper feed tray 202, there are provided a half-moon roller (paper feed roller) 243 that separates and feeds the paper 242 one sheet at a time from the paper loading section 241, and a separation pad 244 that faces the paper feed roller 243 and is made of a material with a large friction coefficient, and this separation pad 244 is biased toward the paper feed roller 243.

[0029] In order to feed the paper 242 fed from this paper feed section below the recording head 234, the printer is provided with a guide member 245 for guiding the paper 242, a counter roller 246, a transport guide member 247, and a pressing member 248 having a tip pressure roller 249, as well as a transport belt 251 which is a transport means for electrostatically adsorbing the fed paper 242 and transporting it to a position facing the recording head 234. The transport belt 251 is an endless belt that is stretched between a transport roller 252 and a tension roller 253 and is configured to rotate in the belt transport direction (sub-scanning direction).

[0030] Also, a charging roller 256 is provided as a charging means for charging the surface of the conveyor belt 251. The charging roller 256 is arranged to contact the surface of the conveyor belt 251 and rotate following the rotation of the conveyor belt 251. The conveyor belt 251 moves in a circular motion in the belt conveying direction as the conveyor roller 252 is rotated and driven by the sub-scanning motor via timing.

[0031] Furthermore, as a paper discharge section for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the conveyor belt 251, a paper discharge roller 262 and a paper discharge roller 263 are provided, and a paper discharge tray 203 is provided below the paper discharge roller 262.

[0032] A duplex unit 271 is detachably attached to the rear of the device body. This duplex unit 271 takes in the paper 242 returned by the reverse rotation of the conveyor belt 251, inverts it, and feeds it again between the counter roller 246 and the conveyor belt 251. The upper surface of this duplex unit 271 serves as a manual feed tray 272.

[0033] Furthermore, a maintenance and recovery mechanism 281 for maintaining and recovering the state of the nozzles of the recording head 234 is disposed in a non-printing region on one side in the scanning direction of the carriage 233. This maintenance and recovery mechanism 281 includes cap members (hereinafter referred to as caps) 282a, 282b (when no distinction is made, they are referred to as caps 282) for capping the nozzle faces of the recording head 234, a wiper blade 283 which is a blade member for wiping the nozzle face, and an idle discharge receiver 284 for receiving droplets when idle discharge is performed to discharge droplets that do not contribute to recording in order to expel thickened recording liquid.

[0034] In addition, in the non-printing area on the other side of the scanning direction of the carriage 233, an ink recovery unit (idle discharge receiver) 288 is arranged, which is a liquid recovery container that receives droplets when idle discharge is performed to discharge droplets that do not contribute to recording in order to discharge recording liquid that has thickened during recording, etc., and this ink recovery unit 288 is equipped with an opening 289 aligned in the nozzle row direction of the recording head 234.

[0035] In this image forming apparatus configured as described above, sheets of paper 242 are separated and fed one by one from paper feed tray 202. The sheets of paper 242 fed approximately vertically upward are guided by guide member 245, sandwiched between conveyor belt 251 and counter roller 246, and conveyed. The leading end of the sheets of paper 242 is further guided by conveyor guide 237 and pressed against conveyor belt 251 by leading end pressure roller 249, and the conveying direction is changed by approximately 90°.

[0036] At this time, an alternating voltage is applied to the charging roller 256 so that positive and negative outputs are alternately repeated, and the conveyor belt 251 is charged with an alternating charging voltage pattern, that is, the conveyor belt 251 is charged with alternating positive and negative charges in a band shape of a predetermined width in the sub-scanning direction which is the rotation direction. When the paper 242 is fed onto the conveyor belt 251 which is alternately charged with positive and negative charges, the paper 242 is attracted to the conveyor belt 251, and the paper 242 is conveyed in the sub-scanning direction by the rotation of the conveyor belt 251.

[0037] Therefore, by driving the recording head 234 in response to an image signal while moving the carriage 233, ink droplets are ejected onto the stationary paper 242 to record one line, and after transporting the paper 242 a predetermined distance, the next line is recorded. Upon receiving a recording end signal or a signal indicating that the rear end of the paper 242 has reached the recording area, the recording operation is ended and the paper 242 is discharged to the paper discharge tray 203.

[0038] FIG. 6 is a cross-sectional view showing another example of the configuration of the image forming apparatus according to the first embodiment. FIG. 7 is a top view of the image forming apparatus according to the first embodiment. As shown in FIG. 6 and FIG. 7, the image forming apparatus according to the present embodiment is a line-type image forming apparatus, and includes an apparatus main body, a paper feed tray 20 for stacking and feeding paper 10, a paper discharge tray 30 for discharging and stacking printed paper 10, a transport unit 40 for transporting paper 10 from the paper feed tray 20 to the paper discharge tray 30, an image forming unit 51 including a head module array 50 constituting a recording head 101 for ejecting and printing droplets (liquid) such as ink onto the paper 10 transported by the transport unit 40, a head cleaning device 60 which is a maintenance and recovery mechanism for performing maintenance and recovery of a plurality of heads of each head module array 50 of the image forming unit 51 after printing is completed or at a required timing, a transport guide unit 70 for opening and closing the head cleaning device 60, and an ink supply system consisting of a sub-tank and a main tank for supplying ink to the head module array 50 of the image forming unit 51. The sheet 10, which is the recording medium, is not limited to paper, and sheets made of other materials such as OHP sheets may also be used.

[0039] The device body is composed of front and rear side panels, stays, etc., and the sheets 10 loaded on the paper feed tray 20 are fed one by one to the transport unit 40 by the separation roller 21 and the paper feed roller 22. The transport unit 40 includes a transport drive roller 41A, a transport driven roller 41B, and an endless transport belt 43 wound around these rollers 41A and 41B. A plurality of suction holes are formed on the surface of the transport belt 43, and a suction fan 44 that sucks the sheets 10 is disposed below the transport belt 43. In addition, transport guide rollers 42A and 42B are held by guides above the transport drive roller 41A and the transport driven roller 41B, respectively, and are in contact with the transport belt 43 by their own weight.

[0040] The conveyor belt 43 rotates as the conveyor drive roller 41A is rotated by a motor, and the paper 10 is sucked onto the conveyor belt 43 by a suction fan 44 and conveyed by the circular movement of the conveyor belt 43. The conveyor driven roller 41B and the conveyor guide rollers 42A and 42B rotate following the conveyor belt 43.

[0041] An image forming unit 51, which is composed of a head module array 50 that ejects droplets to be printed on paper 10, is disposed above transport unit 40 so as to be movable in the direction of arrow A (and the opposite direction). This image forming unit 51 is moved to above head cleaning device 60 during maintenance and recovery operations (cleaning), and is returned to the position shown in FIG. 6 when forming an image.

[0042] The image forming unit 51 has a head module array 50 constituting a line-type recording head that ejects droplets of four colors of ink (yellow Y, magenta M, cyan C, and black K) onto the paper 10 that is attracted to and held on the conveyor belt 43 and conveyed. The head module array 50 is integrally provided with a branching member 54 that distributes and supplies ink to the recording heads 101 of each row. The branching member 54 is supplied with ink from a sub-tank, and the sub-tank is supplied with ink from a main tank. Note that the ink colors used are not limited to these four colors, and there are also cases where colors such as red, green, blue, and gray are added to expand the range of colors or gradations that can be reproduced.

[0043] Furthermore, the recording heads 101 are arranged so that one or more nozzles 3-1 at the ends of two adjacent recording heads 101 (one example of a liquid ejection head) in the head arrangement direction (X direction in FIG. 7, a direction perpendicular to the paper transport direction) overlap (overlap). This allows recording to be performed at the same recording position (dot position) by the nozzles 3-1 of each of the two recording heads 101. The nozzles 3-1 at the ends of the recording heads 101 that can record at this same recording position are called overlapping nozzles 3-1, and the area of ​​the overlapping nozzles 3-1 is called the joint portion, the nozzle row overlapping portion, the overlapping nozzle area (or portion), or the overlap area (or portion).

[0044] A transport guide section 70 is provided downstream of the transport unit 40 to discharge the paper 10 onto the paper output tray 30. The paper 10, which is guided and transported by the transport guide section 70, is discharged onto the paper output tray 30. The paper output tray 30 is provided with a pair of side fences 31 that regulate the width of the paper 10 and an end fence 32 that regulates the leading edge of the paper 10.

[0045] The head cleaning device 60 is a maintenance and recovery mechanism, and includes a cap member 62 and a wiper member corresponding to each recording head 101 of the image forming unit 51, and a suction pump 63 for sucking ink from the nozzles 3-1 while the nozzle surface (the surface on which the nozzles 3-1 are formed) of the nozzles 3-1 of the recording head 101 is capped with the cap member 62.

[0046] In this image forming apparatus, when ink is sucked from the nozzles 3-1 of the recording head 101 that ejects droplets while the nozzle surface of the nozzles 3-1 is capped with the cap member 62 of the head cleaning device 60 after printing is finished, or when ink adhering to the nozzle surface of the nozzles 3-1 of the recording head 101 is cleaned with a wiping member, the entire transport unit 40 rotates in the direction of arrow B around the transport driven roller 41B as a fulcrum after printing is stopped, as shown in Fig. 6, to make the space between the image forming unit 51 larger than that during image formation, thereby ensuring the movement space of the image forming unit 51. At this time, the transport guide plate 71 of the transport guide section 70 disposed on the upper part of the head cleaning device 60 is also rotated upward in the direction of arrow C around the fulcrum 72, and the upper part of the head cleaning device 60 is opened.

[0047] Then, after the transport unit 40 and the transport guide portion 70 are each released (unlocked), the image forming unit 51 moves in the paper passing direction (the direction of arrow A) and is stopped above the head cleaning device 60, and the cap member 62 etc. rises to perform a cleaning operation (maintenance recovery operation) of the recording head 101.

[0048] Fig. 8 is a diagram for explaining an example of the configuration of a drive circuit for the piezoelectric elements in the recording head of the image forming apparatus according to the first embodiment. In this embodiment, the drive circuit for driving N+L piezoelectric elements X includes a host device circuit 900 and a circuit 910 in the head Md. Here, the drive circuit for the recording head 101 shown in Figs. 6 and 7 will be explained, but the drive circuit for the recording head 234 shown in Figs. 4 and 5 also has a similar configuration.

[0049] The higher-level device circuit 900 has a control circuit 901, a waveform generating circuit 902, and a DRV (driver) circuit 903. The circuit 910 in the head Md is a circuit in which a memory 911, a waveform generating circuit 912, a DRV (driver) circuit 913, an analog switch (ASW) Y, and the like are mounted.

[0050] The analog switch Y is an example of a waveform selection control circuit that selects a drive waveform for the piezoelectric element X of the nozzle 3-1 of the printhead 101. In this embodiment, the analog switch Y selects a drive waveform generated by a waveform generating circuit 902 of the higher-level device circuit 900 or a drive waveform generated by a waveform generating circuit 912 (described later) as the drive waveform to be applied to the piezoelectric element X.

[0051] The waveform generating circuit 912 generates a waveform for each of the piezoelectric elements X (piezoelectric element X 1~n , Piezoelectric element X N~N+L ) position, analog switch (ASW) Y (analog switch Y 1~n ,Y N~N+L 913) in parallel with the printhead 101. This is an example of a drive waveform generating circuit that generates a drive waveform. As a result, the drive circuits for the piezoelectric elements X (e.g., the memory 911, the waveform generating circuit 912, and the driver circuit 913) are installed only at the connection portion of the nozzle 3-1 of the printhead 101, so that it is possible to suppress an increase in size and cost due to an increase in the scale of the drive circuit built into the printhead 101.

[0052] The memory 911 stores a voltage correction magnification value (an example of a correction voltage value) of the waveform voltage of the drive waveform. That is, the memory 911 is an example of a memory circuit that is provided corresponding to the waveform generating circuit 912 and stores the voltage correction magnification value of the drive waveform generated by the waveform generating circuit 912. In this embodiment, the waveform generating circuit 912 may generate a waveform obtained by correcting the drive waveform generated by the waveform generating circuit 902 of the upper device circuit 900 based on the voltage correction magnification value stored in the memory 911 as the drive waveform of the piezoelectric element X. For example, the waveform generating circuit 912 may correct the waveform voltage of the drive waveform generated by the waveform generating circuit 902 or the drive waveform to increase or decrease the ejection speed of the liquid from the nozzle 3-1.

[0053] The upper device circuit 900 is a waveform generating circuit 902 and a DRV (driver) circuit 903 that controls the piezoelectric element X (piezoelectric element X1 to piezoelectric element X N+LThe head Md internal circuit 910 is configured to drive the piezoelectric elements X1, X2, X3, and X4, which correspond to both ends of the nozzle 3-1 of the recording head 101, by a waveform generating circuit 912 and a DRV (driver) circuit 913. 1~n ,X N~N+L The configuration is to drive the following:

[0054] As a result, the piezoelectric elements X that correspond to both ends of the nozzle 3-1 1~n ,X N~N+L can select driving by a waveform generating circuit 902 and a DRV (driver) circuit 903 in a host device circuit 900, or driving by a waveform generating circuit 912 and a DRV (driver) circuit 913 in a circuit 910 in the head Md.

[0055] Furthermore, the waveform generating circuit 912 of the circuit 910 in the head Md is configured to be able to correct the waveform voltage of the output waveform (driving waveform) and the timing of application of the driving waveform by setting a memory 911 that stores a voltage correction value.

[0056] 9 and 10 are diagrams for explaining an example of a correction process of a dot position corresponding to a nozzle position of an image forming apparatus according to a first embodiment. FIG. 9(a) is a diagram for explaining a dot position corresponding to a nozzle position of a conventional configuration, and FIG. 9(b) is a diagram for explaining a dot position corresponding to a nozzle position in this embodiment. In FIG. 9, the vertical axis represents a dot position on the paper surface, and the horizontal axis represents a position of the nozzle 3-1 (nozzle position). In FIG. 10, the vertical axis represents a waveform voltage of a drive waveform that drives a piezoelectric element X of the nozzle 3-1 of the recording head 101, and the horizontal axis represents time.

[0057] In conventional configurations, due to manufacturing variations in recording heads 101-1 to 101-3 (an example of a liquid ejection head), differences in ejection speed due to nozzle position can occur at the joint between recording head 101-1 and recording head 101-2, and at the joint between recording head 101-2 and recording head 101-3, as shown in FIG. 9(a).

[0058] In the example of FIG. 9(a), the ejection speed of the print head 101-1 is ch N (piezoelectric element X N )~ch N+L(piezoelectric element X N+L ), and the ejection speed of the recording head 101-2 increases from ch 1 (piezoelectric element X1) to ch n (piezoelectric element X n ), and the ejection speed of the recording head 101-2 decreases from ch N (piezoelectric element X N ) to ch N+L (piezoelectric element X N+L ), and the ejection speed of the print head 101-3 increases from ch 1 (piezoelectric element X1) to ch n (piezoelectric element X n ) As a result, the dot position deviation on the paper surface occurs at the joint of the nozzle 102a.

[0059] As an example of correcting the dot position deviation at the joints of the nozzles 102a, as shown in FIG. 1~n ,X N~N+L As shown in FIG. 10(a), the waveform generating circuit 912 corrects the waveform voltage of the driving waveform that drives the piezoelectric element X of the recording head 101 from V1 to V2 to increase the ejection speed, and conversely, corrects the waveform voltage from V1 to V3 to decrease the ejection speed, so that the dot positions on the paper surface at the joints are aligned.

[0060] 10(b), the drive waveform for driving the piezoelectric element X of the print head 101 is corrected from t1 to t2 to correct the landing position of the ejection timing to increase the ejection speed, and conversely, the drive waveform is corrected from t1 to t3 to decrease the ejection speed so that the dot positions on the paper surface at the joints match. Also, the correction voltage value or correction timing value for each nozzle 3-1 can be set during image adjustment by the printer system or at the time of shipment from the factory.

[0061] In this way, according to the image forming apparatus of the first embodiment, the driving circuits (for example, the memory 911, the waveform generating circuit 912, and the driver circuit 913) for the piezoelectric elements X are installed only at the connecting portions of the nozzles 3-1 of the printhead 101, so that it is possible to suppress an increase in size and cost due to an increase in the scale of the driving circuits built into the printhead 101. Also, it is possible to change the ejection speed or ejection timing of droplets of ink or the like from the nozzles 3-1 of the printhead 101. Furthermore, it is possible to suppress deviation of the dot positions at the ends of the nozzles 3-1.

[0062] (Second embodiment) This embodiment is an example that includes a first waveform selection control circuit that selects a drive waveform for a piezoelectric element of a nozzle of a liquid ejection head, and a second waveform selection control circuit that is mounted in parallel with the first waveform selection control circuit at the position of the piezoelectric element of the nozzle at both ends of the liquid ejection head. In the following explanation, explanations of the same configuration as in the first embodiment will be omitted.

[0063] 11 is a diagram for explaining an example of another circuit configuration according to the second embodiment. In this embodiment, a host device circuit 900 and a circuit 910 in the head Md are provided as a drive circuit for driving N+L piezoelectric elements X. The host device circuit 900 has a control circuit 901, a waveform generating circuit 902, and a DRV (driver) circuit 903.

[0064] Piezoelectric element X 1~N ,X N~N+L For analog switch Y (analog switch Y 1~N+L ) and analog switch Z (Z 1~n ,Z N~N+L ) are installed (mounted, connected) in parallel. The analog switch Y is an example of a first waveform selection control circuit that selects the drive waveform of the piezoelectric element X of the nozzle 3-1 of the printhead 101. The analog switch Z is an example of a first waveform selection control circuit that selects the drive waveform of the piezoelectric element X of the nozzle 3-1 of the printhead 101. 1~n ,X N~N+LThis is an example of a second waveform selection control circuit mounted (connected) in parallel with analog switch Y at position 1. This makes it possible to change the ON resistance of analog switches Y and Z by changing the switching timing of both analog switches Y and Z, thereby adjusting the applied voltage (waveform voltage) of piezoelectric element X.

[0065] In this way, according to the image forming apparatus of the second embodiment, the drive circuit (e.g., analog switch Z) of the piezoelectric element X is installed only at the connection portion of the nozzle 3-1 of the recording head 101, so that it is possible to suppress an increase in size and cost due to an increase in the scale of the drive circuit built into the recording head 101.

[0066] In the above embodiment, the image forming apparatus of the present invention is described as being applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus can be applied to any image forming apparatus such as a copier, a printer, a scanner device, or a facsimile device.

[0067] In this embodiment, the liquid ejection head (recording head 234, recording head 101) is not limited to a pressure generating means. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element X) as described in the above embodiment, a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a vibration plate and an opposing electrode may be used.

[0068] In addition, the terms "image formation," "recording," "printing," "imaging," "printing," "shaping," and the like in this application are all the same. It is a synonym.

[0069] In the present embodiment, the liquid ejection unit is a collection of components related to ejecting liquid, in which functional components and mechanisms are integrated with a liquid ejection head. For example, the liquid ejection unit may include a combination of a liquid ejection head and at least one of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism.

[0070] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0071] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated together. There are also liquid ejection units in which the liquid ejection head and the head tank (e.g., the head tank 235) are integrated together by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0072] Furthermore, there is a liquid ejection unit in which a liquid ejection head and a carriage (for example, the carriage 233) are integrated.

[0073] In some liquid ejection units, the liquid ejection head is movably held by a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together, and in some liquid ejection units, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0074] Also, there is a liquid ejection unit in which a cap member (e.g., cap 282), which is part of a maintenance and recovery mechanism (e.g., maintenance and recovery mechanism 281), is fixed to a carriage on which a liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0075] In addition, some liquid ejection units have a head tank or a liquid ejection head to which a flow path component is attached, and a tube (e.g., a supply tube 236) is connected to the liquid ejection head, integrating the liquid ejection head with a supply mechanism. Liquid from a liquid storage source is supplied to the liquid ejection head via this tube.

[0076] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0077] In the present embodiment, a liquid ejection device (liquid ejection device) is a device that includes a liquid ejection head or a liquid ejection unit, and ejects liquid by driving the liquid ejection head. Liquid ejection devices include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0078] The device for discharging this liquid may also include means for feeding, transporting, and discharging items onto which the liquid can be attached, as well as pre-processing devices and post-processing devices.

[0079] For example, devices that eject liquid include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices (three-dimensional modeling devices) that eject modeling liquid onto a powder layer formed in layers of powder in order to create a three-dimensional object (a three-dimensional model).

[0080] Furthermore, the liquid ejecting device is not limited to one that visualizes meaningful images such as letters and figures by ejecting liquid. For example, it also includes one that forms patterns that have no meaning in themselves and one that models three-dimensional images.

[0081] In this embodiment, something to which liquid can adhere means something to which liquid can adhere at least temporarily, something to which liquid adheres and sticks, something to which liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, etc., electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, all things to which liquid can adhere are included.

[0082] The materials to which the liquid can be attached include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, etc., so long as the liquid can be attached even temporarily.

[0083] The liquid may have a viscosity and surface tension that allows it to be discharged from a liquid discharge head, and is not particularly limited, but is preferably one whose viscosity becomes 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, an edible material such as a natural colorant, etc., and these can be used for applications such as inkjet ink, surface treatment liquid, a liquid for forming a component of an electronic element or a light-emitting element, an electronic circuit resist pattern, a material liquid for three-dimensional modeling, etc.

[0084] Furthermore, the liquid ejection device may be a device in which the liquid ejection head and an object to which the liquid can adhere move relatively, but is not limited to this. Specific examples include a serial type device in which the liquid ejection head moves, a line type device in which the liquid ejection head does not move, etc.

[0085] Other examples of devices that eject liquid include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials. [Explanation of symbols]

[0086] 3-1 Nozzle 101,234 recording head 900 Upper device circuit 901 Control circuit 902,912 Waveform generation circuit 903,913 DRV circuit 910 Head Md internal circuit 911 Memory X Piezoelectric element Y,Z Analog Switch [Prior art documents] [Patent documents]

[0087] [Patent Document 1] Patent No. 3546929 [Patent Document 2] JP 2016-165819 A

Claims

1. a waveform selection control circuit that selects a drive waveform for a piezoelectric element of a nozzle of the liquid ejection head; a drive waveform generating circuit that is mounted in parallel with the waveform selection control circuit at the position of the piezoelectric element of the nozzle at both ends of the liquid ejection head and that generates the drive waveform; a memory circuit corresponding to the drive waveform generating circuit and storing a correction voltage value of the drive waveform; A circuit in a head module comprising:

2. The head module internal circuit according to claim 1 , wherein the waveform selection control circuit selects the drive waveform generated by an external higher-level device circuit or the drive waveform generated by the drive waveform generation circuit.

3. 3. The circuit in the head module according to claim 1, wherein the drive waveform generating circuit corrects a waveform voltage of the drive waveform or the drive waveform to increase or decrease a discharge speed of the liquid from the nozzle.

4. a first waveform selection control circuit that selects a drive waveform for a piezoelectric element of a nozzle of the liquid ejection head; a second waveform selection control circuit mounted in parallel with the first waveform selection control circuit at the positions of the piezoelectric elements of the nozzles at both ends of the liquid ejection head; A circuit in a head module comprising:

5. A nozzle; a piezoelectric element that is driven by application of a drive waveform to eject liquid from the nozzle; A waveform selection control circuit for selecting the drive waveform; a drive waveform generating circuit that is mounted in parallel with the waveform selection control circuit at the position of the piezoelectric element of the nozzle at both ends and generates the drive waveform; a memory circuit corresponding to the drive waveform generating circuit and storing a correction voltage value of the drive waveform; A liquid ejection head comprising:

6. A nozzle; a piezoelectric element that is driven by application of a drive waveform to eject liquid from the nozzle; a first waveform selection control circuit that selects a drive waveform for the piezoelectric element; A second waveform selection control circuit is mounted in parallel with the first waveform selection control circuit at the positions of the piezoelectric elements of the nozzles at both ends; A liquid ejection head comprising:

7. A liquid ejection unit comprising the liquid ejection head according to claim 5 or 6.

8. A liquid ejection device comprising the liquid ejection unit according to claim 7.

9. An image forming apparatus comprising the liquid ejection device according to claim 8.

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