JP2017087507A - Droplet discharge unit, droplet discharge method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge method that can reduce influences by residual vibration and keep productivity.SOLUTION: A device which has a discharge head 209 for discharging a plurality of droplets to relatively moving recording media, performs control, on the basis of data to be input, so that the droplets are discharged to the recording media. In the control, elapsed time from a time when a first liquid droplet which is discharged first out of the plurality of droplets to be discharged from the discharge head is discharged or from a time when the discharge head is vibrated until a time when a second liquid droplet is discharged, is set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a unit for ejecting droplets, a method for ejecting droplets, and a program.

  Conventionally, in ink jet image formation, when ink is ejected from an ink jet head, it is known that residual vibration remains on a diaphragm or a meniscus and affects subsequent ejection. In order to reduce the influence of this residual vibration, a method for suppressing the residual vibration is known.

  For example, in an ink jet printer in which a piezoelectric element is provided in an ink chamber of a nozzle, a method of displacing the piezoelectric element in a direction that can suppress long-period meniscus vibration at a predetermined timing is known (see, for example, Patent Document 1).

  However, in the conventional technology, the problem is that the influence of residual vibration such as long-period vibration due to meniscus cannot be reduced and productivity cannot be maintained.

  An object of one aspect of the present invention is to provide an image forming apparatus capable of reducing the influence of residual vibration and maintaining productivity.

  In order to solve the above-described problems, a unit for ejecting liquid droplets, which is an aspect of the present invention, includes a discharge head that ejects liquid droplets and a data that is input to a relatively moving recording medium. And a control unit that performs control to discharge the droplets to the recording medium. The control unit first discharges the plurality of droplets discharged from the discharge head. An elapsed time from when the droplet is discharged or when the discharge head is vibrated until the second droplet is discharged is set.

  The effect of residual vibration can be reduced and productivity can be maintained.

1 is an external view illustrating an example of an ejection head included in an image forming apparatus according to an embodiment of the present invention. 2 is a cross-sectional view illustrating an example of an ejection head included in an image forming apparatus according to an embodiment of the present disclosure. FIG. 1 is a block diagram illustrating a hardware configuration example of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a configuration example of a print control device and a head driver included in an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating an example of an image forming system having an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the hardware structural example of the image processing apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the relationship between the elapsed time which concerns on one Embodiment of this invention, and a discharge speed. It is a figure which shows an example of the image formed. It is a figure which shows the example which overlap arises by a residual vibration. It is a figure which shows an example of the image formed by the 1st discharge pattern which concerns on one Embodiment of this invention. It is a figure which shows an example of the image formed by the 2nd discharge pattern which concerns on one Embodiment of this invention. It is a figure which shows the example which a separation produces by a residual vibration. It is a figure which shows an example of the image formed by the 3rd discharge pattern which concerns on one Embodiment of this invention. It is a figure which shows another example which overlaps with a residual vibration. It is a figure which shows an example of the image formed by the discharge pattern using the droplet etc. which concern on one Embodiment of this invention. 1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating an example of a mechanism portion included in an image forming apparatus according to an embodiment of the present invention. It is a schematic diagram showing an example of another overall configuration of an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating an example of overall processing by the image forming apparatus according to the embodiment of the present disclosure. 1 is a functional block diagram illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that, in the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment>
<Example of discharge head of image forming apparatus>
An apparatus for discharging droplets is, for example, an image forming apparatus. That is, when the image forming apparatus ejects droplets, the ejected droplets are a recording liquid such as ink. Hereinafter, an example of the image forming apparatus will be described. Note that the configuration for discharging droplets may be a unit in which the configuration for discharging droplets is integrated, such as a unit for discharging droplets.

  FIG. 1 is an external view showing an example of an ejection head included in an image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to an embodiment of the present invention includes, for example, an ejection head 209 as illustrated. FIG. 1A is a view of the ejection head 209 viewed from the so-called nozzle direction, that is, a plan view. On the other hand, FIG. 1B is a side view of the ejection head 209, that is, a side view.

  Hereinafter, the direction in which the nozzles 4 included in the ejection head 209 are arranged (corresponding to the horizontal direction in the figure) is defined as the x axis. Further, a direction orthogonal to the x axis is taken as a y axis. The vertical direction is the z-axis.

  In the example shown in the figure, there are a plurality of nozzles 4 arranged in the x-axis direction. In this example, a nozzle group 102 is configured by a plurality of nozzles 4. Specifically, as shown in the drawing, a plurality of nozzles 4 are arranged so as to form a first row 102a and a second row 102b, and a nozzle group 102 is configured. As shown in the figure, the second row 102b is a position where there is no nozzle 4 constituting the first row 102a, that is, a position for interpolating between the nozzles 4 constituting the first row 102a. Installed.

  Further, the ejection head 209 includes a flow path member 1 (also referred to as a “droplet substrate”) that forms a flow path through which droplets flow. Furthermore, the illustrated configuration is an example in which the diaphragm member 2 is joined to the lower surface of the flow path member 1. On the other hand, in this example, the nozzle plate 3 is joined to the upper surface of the flow path member 1 with an adhesive or the like. Furthermore, the frame member 17 is joined to the diaphragm member 2 by an adhesive or the like.

  The flow path member 1, the vibration plate member 2, the nozzle plate 3, the frame member 17, and the like form a flow path in which a liquid that is a droplet discharged from the nozzle 4 flows or a liquid chamber in which the liquid is stored.

  Further, the damper member 20 is used on at least one of the wall surfaces of the liquid chamber to be formed. The damper member 20 is less rigid than the wall surface that is the frame member 17. Furthermore, the damper member 20 is not limited to one layer, and may be two or more layers. In addition, the damper member 20 may be made of a material different from that of the diaphragm member 2. For example, the damper member 20 is nickel (Ni) metal or the like. That is, the damper member 20 is preferably made of a material having low gas permeability such as nickel metal. The damper member 20 may be formed of a resin film or the like.

  FIG. 2 is a cross-sectional view illustrating an example of an ejection head included in an image forming apparatus according to an embodiment of the present invention. As shown in the drawing, an individual flow path (hereinafter referred to as “pressurized liquid chamber”) 6 is formed in the ejection head. Each nozzle 4 communicates with the pressurized liquid chamber 6. Further, the ejection head has a communication portion 9 provided with the diaphragm member 2 for each pressurized liquid chamber 6. Furthermore, the ejection head has a communication portion 10 formed in the flow path member 1.

  A common liquid chamber 8 is formed in the frame member 17. The common liquid chamber 8 supplies the recording liquid to each pressurized liquid chamber 6. Specifically, the recording liquid is supplied from the common liquid chamber 8 via the liquid resistance portion 7. A liquid, that is, a recording liquid is supplied from the common liquid chamber 8 to each pressurized liquid chamber 6 through a communication portion 9 formed in the diaphragm member 2. Note that a recording liquid supply port is formed in the frame member 17 in order to supply the recording liquid from the outside to the common liquid chamber 8. The common liquid chamber 8 is formed in a rectangular shape with a planar shape in the direction in which the pressurized liquid chambers 6 are arranged, that is, in the direction in which the nozzles are arranged (hereinafter sometimes referred to as “longitudinal direction of the common liquid chamber”). The

  In addition, the flow path member 1 forms an opening, a groove | channel, etc. in each pressurized liquid chamber 6, the liquid resistance part 7, the communication part 10, etc. FIG. These can be formed, for example, when anisotropic etching using an alkaline etching solution such as a potassium hydroxide aqueous solution (KOH) is performed on a single crystal silicon substrate having a crystal plane orientation (Miller index 110). In addition, when machining such as etching or punching using an acidic etchant is performed on the SUS substrate, each pressurized liquid chamber 6 can be formed. Further, the flow path member 1, the nozzle plate 3, and the vibration plate member 2 can be integrally formed by electroforming. Furthermore, photosensitive resin etc. may be used for these formation.

  The diaphragm member 2 is formed with a nickel plate having a three-layer structure in the order of the first layer 2a, the second layer 2b, and the third layer 2c from the pressurized liquid chamber 6 side. The diaphragm member 2 is formed by, for example, electroforming. Furthermore, the diaphragm member 2 may be formed of, for example, a laminated member of a resin member such as polyimide and a metal plate such as a SUS substrate. Furthermore, the diaphragm member 2 may be formed of a resin member or the like.

  In the nozzle plate 3, a plurality of nozzles 4 are formed for each pressurized liquid chamber 6. For example, the nozzle plate 3 is a metal such as stainless steel or nickel, a resin such as a polyimide resin film, silicon, or a combination thereof.

  Further, the inner shape of the nozzle 4, that is, the inner shape, is formed in a horn shape, for example. The internal shape of the nozzle 4 may be a substantially cylindrical shape or a truncated cone shape. Further, the hole diameter of the nozzle 4 is about 14 to 35 micrometers in diameter on the outlet side from which droplets are discharged.

  The nozzle plate 3 and the nozzle surface (surface in the direction in which droplets are discharged, that is, the discharge surface) are provided with a water-repellent treatment layer subjected to a water-repellent surface treatment. The water repellent layer is, for example, PTFE-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor deposition coating of evaporable fluororesin (for example, fluorine pitch), silicon-based resin or fluororesin solvent Baking after application is selected according to the physical properties of the recording liquid. The water-repellent treatment layer stabilizes the droplet shape and flight characteristics of the recording liquid so that high quality image quality can be obtained.

  The diaphragm member 2 is formed of the first layer 2a with respect to each pressurized liquid chamber 6, and the second layer is formed at the center of the diaphragm portion (vibration region) 2A which is a deformable region. A convex portion 2B having a laminated structure of 2b and the third layer 2c is formed. The laminated piezoelectric elements 12A constituting the pressure generating means (actuator) are respectively joined to the convex portions 2B.

  The plurality of piezoelectric elements 12 </ b> A are formed in a comb-teeth shape without being divided by performing half-cut groove processing (slit processing) on one piezoelectric element member 12. The piezoelectric element member 12 is disposed on the base member 13 along the direction in which the plurality of piezoelectric elements 12A are arranged. In this case, the plurality of piezoelectric elements 12 </ b> A arranged in a row are a piezoelectric element that is driven and a piezoelectric element that is not driven and serves as a support column. In addition, the piezoelectric element which does not drive which becomes a support | pillar part is joined to the location used as the partition part between liquid chambers.

  The piezoelectric element member 12 includes, for example, a lead zirconate titanate (PZT) piezoelectric layer having a thickness of about 10 to 50 micrometers / layer and a silver / palladium (AgPd) having a thickness of about several micrometers / layer. And internal electrode layers made up of).

  In the piezoelectric element member 12, the internal electrode layers are alternately connected to the individual electrode and the common electrode which are the end surface electrodes (external electrodes) 16 on the end surfaces. This voltage constant indicates the expansion and contraction in the direction perpendicular to the internal electrode surface which is the so-called d33 direction, that is, in the thickness direction. Further, the vibration region 2A is displaced by the expansion and contraction of the piezoelectric element 12A. When the vibration region 2A is displaced, the pressurized liquid chamber 6 contracts or expands. Thus, when a drive signal is applied to the piezoelectric element 12A and charging is performed, the piezoelectric element 12A expands. On the other hand, when the electric charge charged in the piezoelectric element 12A is discharged, the piezoelectric element 12A contracts.

  Note that the liquid in the pressurized liquid chamber 6 may be pressurized using a displacement in the d33 direction in the piezoelectric direction of the piezoelectric element member 12. Alternatively, the liquid in the pressurized liquid chamber 6 may be pressurized using displacement in the so-called d31 direction in the piezoelectric direction of the piezoelectric element member 12. Hereinafter, a configuration using displacement in the d33 direction will be described as an example.

  The base member 13 is preferably formed of a metal material. When the base member 13 is formed of a metal material, heat storage due to self-heating of the piezoelectric element member 12 can be reduced.

<Hardware configuration example>
FIG. 3 is a block diagram illustrating a hardware configuration example of an image forming apparatus according to an embodiment of the present invention. For example, an image forming apparatus according to an embodiment of the present invention has the illustrated hardware configuration.

  The image forming apparatus includes a CPU (Central Processing Unit) 201, a ROM (Read-Only Memory) 202, and a RAM (Random Access Memory) 203. The image forming apparatus also includes an NVRAM (Non-Volatile RAM) 204 and an ASIC (Application Specific Integrated Circuit) 205. Further, the image forming apparatus includes a host I / F (interface) 206, a print control device 207, a carriage 30, a motor drive device 210, an AC bias supply device 212, and an I / O (Input / Output) 213. Furthermore, the image forming apparatus includes an operation panel 214, a temperature sensor 215, a main scanning motor 40, an encoder sensor 43, a sub scanning motor 31, a conveyance belt 21, an encoder sensor 35, and a charging roller 26.

  The CPU 201 controls the entire image forming apparatus. That is, the CPU 201 is a calculation device that performs calculations for realizing the processing and data processing performed by the control unit 200. The CPU 201 is a control device that controls the illustrated hardware.

  The ROM 202, the RAM 203, and the NVRAM 204 are examples of storage devices. Specifically, the ROM 202 stores a program executed by the CPU 201 and data such as fixed data. The RAM 203 stores data such as image data. Further, since the NVRAM 204 can retain data even when the power of the image forming apparatus is shut off, the NVRAM 204 stores data to be retained even when the power of the image forming apparatus is shut off.

  The ASIC 205 is an electronic circuit that performs various signal processing on image data, image processing such as rearrangement, and input / output signal processing for controlling the entire image forming apparatus.

  The host I / F 206 is an interface for transmitting / receiving data to / from the host side.

  The print control device 207 transmits data for driving the ejection head 209 and the like. In addition, the print control apparatus 207 generates and transmits a drive waveform.

  The carriage 30 is realized by the head driver 208, the ejection head 209, and the like. The head driver 208 is a driver IC (Integrated Circuit) for driving the ejection head 209 provided on the carriage 30 side.

  The motor driving device 210 drives the main scanning motor 40 and the sub scanning motor 31.

  The AC bias supply device 212 supplies an AC bias to the charging roller 26.

  The encoder sensor 43 outputs a detection signal indicating the position of the main scanning motor 40. Similarly, the encoder sensor 35 outputs a detection signal indicating the position of the sub-scanning motor 31.

  The temperature sensor 215 measures the environmental temperature of the image forming apparatus and outputs a detection signal.

  The I / O 213 is an interface that inputs detection signals from each sensor.

  The operation panel 214 is a display device that displays various types of information and an input device that inputs user operations.

  For example, the control unit 200 receives image data and the like from an information processing apparatus such as a PC (Personal Computer), an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera, by the host I / F 206. Note that image data or the like is received via a cable or a network. Next, the CPU 201 included in the control unit 200 reads and analyzes image data stored in a reception buffer included in the host I / F 206. Then, the control unit 200 uses the ASIC 205 to perform processing such as image processing and data rearrangement. Subsequently, the image data processed by the ASIC 205 is transmitted to the head driver 208 by the print control device 207. Note that the generation of dot pattern data for image formation is performed by a printer driver on the host side.

  Further, the print control apparatus 207 converts the image data into serial data and transmits it to the head driver 208. Further, the print control device 207 transmits signals such as a clock signal, a latch signal, and a droplet control signal (mask signal) used for transmitting image data to the head driver 208.

  Furthermore, the print control apparatus 207 includes a D / A converter that performs D / A (digital-analog) conversion on data indicating a drive signal pattern stored in the ROM 202 or the like. The print control apparatus 207 also includes a drive waveform generation unit that generates a drive signal using a voltage amplifier that amplifies the signal voltage, a current amplifier that amplifies the signal current, and the like. Further, the print control apparatus 207 includes a drive waveform selection unit that selects a drive waveform transmitted to the head driver 208. Subsequently, one or a plurality of drive waveform pulses, that is, a drive signal is transmitted to the head driver 208 as a drive waveform. Details of the print control apparatus 207 will be described later.

  Image data is transmitted serially to the head driver 208. Further, the image data is transmitted to the head driver 208 as data for one row of the ejection head 209. Based on the data for one row, the head driver 208 applies a drive signal having a drive waveform to the ejection head 209. When a driving signal is applied, a driving element (for example, a piezoelectric element) included in the ejection head 209 generates energy for ejecting a droplet. In this way, the ejection head 209 is driven based on the image data.

  Further, the image forming apparatus selects one of the sizes of, for example, a large droplet (large dot), a medium droplet (medium dot), and a small droplet (small dot) by selecting a driving waveform pulse constituting the driving waveform. As can be seen, the dots can be divided.

  Further, the CPU 201 samples a detection signal transmitted from the encoder sensor 43 that constitutes a linear encoder or the like to obtain a speed detection value, a position detection value, and the like. Next, the CPU 201 drives the drive output value for controlling the main scanning motor 40 based on the speed target value and position target position obtained from the speed and position profile stored in advance, and the speed detection value and position detection value. That is, a control value is calculated. Subsequently, the CPU 201 drives the main scanning motor 40 via the motor driving device 210 based on the control value.

  Similarly, the CPU 201 samples a detection signal transmitted from the encoder sensor 35 that constitutes a rotary encoder or the like to obtain a speed detection value, a position detection value, and the like. Next, based on the speed target value and position target position obtained from the speed and position profile stored in advance, the speed detection value and the position detection value, a drive output value for controlling the sub-scanning motor 31, that is, Calculate the control value. Subsequently, the CPU 201 drives the sub-scanning motor 31 via the motor driving device 210 based on the control value.

  FIG. 4 is a block diagram illustrating a configuration example of a print control device and a head driver included in the image forming apparatus according to the embodiment of the present disclosure. As illustrated, the print control apparatus 207 includes a drive waveform generation unit 301 and a transmission unit 302. On the other hand, the head driver 208 connected to the print control apparatus 207 includes a shift register 311, a latch circuit 312, a decoder 313, a level shifter 314, and an analog switch 315.

  The drive waveform generation unit 301 generates and transmits a drive waveform composed of a plurality of drive pulses, that is, drive signals, that is, a common drive waveform, in one cycle in printing.

  The transmission unit 302 transmits droplet control signals M0 to M3 to the head driver 208. Further, the transmission unit 302 transmits an image data signal, a latch signal, and a clock signal to the head driver 208.

  The image data signal is a signal indicating 2-bit data corresponding to the image to be printed. The gradation signal included in the image data signal is a signal indicating “0” or “1”, respectively. In addition, a clock signal is transmitted to transmit the image data signal.

  The droplet control signals M0 to M3 are 2-bit signals for controlling the opening / closing of the analog switch 315 for each droplet. Specifically, the state transition is performed by the droplet control signals M0 to M3 so that the selected signal is at a high level (ON) in accordance with the printing cycle of the common drive waveform. On the other hand, the state transition is performed by the droplet control signals M0 to M3 so that the unselected signal is set to the Low level (OFF) in accordance with the printing cycle of the common drive waveform.

  The shift register 311 receives a clock signal, that is, a shift clock, and an image data signal that is serial data, that is, gradation data of 2 bits / ch.

  The latch circuit 312 latches each register value from the shift register 311 based on the latch signal.

  The decoder 313 decodes the gradation data and the droplet control signals M0 to M3.

  The level shifter 314 converts the logic level voltage signal output from the decoder 313 to a level at which the analog switch 315 operates.

  The analog switch 315 performs ON / OFF (open / close) based on the output of the decoder 313 output via the level shifter 314.

  A selection electrode (individual electrode) included in each piezoelectric element 121 is connected to the analog switch 315. Further, the common drive waveform transmitted from the drive waveform generation unit 301 is input to each piezoelectric element 121.

  When the analog switch 315 is turned on based on serially transferred image data, that is, gradation data and the result of the decoder 313 decoding the droplet control signals M0 to M3, a predetermined drive signal included in the common drive waveform Is selected. Each piezoelectric element 121 is applied with a drive signal that has passed through the analog switch 315, that is, a selected drive signal.

  FIG. 5 is a block diagram showing an example of an image forming system having an image forming apparatus according to an embodiment of the present invention. As illustrated, the image forming system 700 includes an ink jet printer 500 which is an example of an image forming apparatus. Further, as illustrated, an image processing apparatus such as a PC 400 that performs image processing is connected to the inkjet printer 500. Note that the image forming system 700 may include a plurality of image processing apparatuses.

  The PC 400 has an external I / F 407. Similarly, the inkjet printer 500 includes an external I / F 106. As shown in the figure, in the image forming system 700, the PC 400 and the ink jet printer 500 are connected by an external I / F 407 and an external I / F 106 via a predetermined interface or a network.

  FIG. 6 is a block diagram illustrating a hardware configuration example of an image processing apparatus according to an embodiment of the present invention. For example, an image processing apparatus according to an embodiment of the present invention has the hardware configuration illustrated.

  The PC 400 includes a CPU 401, ROM 402, RAM 403, input device 404, monitor 405, storage device 406, and external I / F 407. As shown, each hardware is connected by a bus line.

  The CPU 401 is an arithmetic device that performs arithmetic operations for realizing processing and data processing performed by the PC 400. The CPU 401 is a control device that controls the illustrated hardware.

  The ROM 402 and the RAM 403 are examples of storage devices. Specifically, the ROM 402 stores a program executed by the CPU 401 and data such as fixed data. The RAM 403 stores data such as image data.

  The input device 404 is a device that inputs user operations and the like to the PC 400. For example, the input device 404 is a mouse or a keyboard.

  The monitor 405 is an example of an output device in which the PC 400 outputs a display or the like to the user. For example, the monitor 405 is an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube).

  The storage device 406 is a hard disk or the like. That is, the storage device 406 is an auxiliary storage device or the like.

  The external I / F 407 is an interface that communicates with an external device via a network such as the Internet or a USB (Universal Serial Bus).

  The PC 400 includes a storage medium reading device that reads a storage medium such as an optical disk.

  The storage device 406 stores a program. This program is read from a storage medium or downloaded from a network and installed in the storage device 406. The PC 400 performs image processing using the program installed in this manner. Note that this program may be a program that operates on a predetermined OS (Operating System). Further, this program may be a part of application software.

  In the image forming method according to the present invention, part or all of the image processing may be performed on the image forming apparatus side. In the following description, an example will be described in which the inkjet printer 500 does not have a function of generating a dot pattern for actually forming an image upon receiving an image drawing or character print command. That is, a print command is generated by application software executed on the PC 400 serving as a host.

  Next, image processing is performed based on a printer driver included in the PC 400, that is, the host. When this image processing is performed, data indicating a dot pattern, that is, print image data is generated. Subsequently, the print image data is rasterized, and the print image data is transmitted to the inkjet printer 500.

  Specifically, first, the PC 400 stores an image or character image formation command by an application software or OS in a drawing data memory or the like. Note that the image formation command indicates, for example, the position, thickness, or shape of a line on which an image is formed when an image is formed. For example, when an image of a character is formed, the typeface, size or position of the character is indicated. Further, the image formation command is described in a specific print language or the like.

  Next, the image formation command stored in the drawing data memory or the like is interpreted by rasterization. Specifically, in the case of an image formation command for forming an image of a line, the image formation command is converted into a dot pattern corresponding to a designated position and thickness.

  In the case of an image formation command for forming an image of a character, character outline data is first called from font-out data stored in the PC 400 or the like. Subsequently, the image formation command is converted into a dot pattern corresponding to the designated position and size based on the contour data. On the other hand, if it is an image formation command for forming an image, the image formation command is converted into a dot pattern indicating an image.

  Image processing is performed on these dot patterns, and data is stored in a raster data memory or the like. The PC 400 rasterizes the dot pattern data using the orthogonal grid as a basic recording position. The image processing is, for example, color management processing (CMM) for adjusting colors, halftone processing such as gamma correction, dithering or error diffusion, ground removal processing, or total ink amount regulation processing. Then, the dot pattern data stored in the raster data memory is transmitted to the ink jet printer 500 via the interface.

  Note that the unit for ejecting liquid droplets has a configuration in which other functional components and mechanisms are integrated with the ejection head, and is an assembly of components related to the function of ejecting liquid droplets. For example, the unit for ejecting droplets includes at least one of a configuration such as a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism in combination with the ejection head. In addition, the integration is, for example, a state in which the ejection head and the functional component or mechanism are fixed to each other by fastening, adhesion, engagement, or the like, or a state in which one is movable relative to the other. Further, the ejection head and the functional component or mechanism may be configured to be detachable from each other.

  In addition, the apparatus which discharges a droplet is not restricted to an image forming apparatus, A solid modeling apparatus, a process liquid coating apparatus, a jet granulation apparatus, etc. may be sufficient. That is, an apparatus for ejecting liquid droplets is an apparatus that includes an ejection head or a unit for ejecting liquid droplets, and drives the ejection head to eject liquid. In addition, the apparatus for ejecting liquid droplets includes not only an apparatus capable of ejecting liquid droplets to an object to which the liquid droplets can adhere, but also an apparatus for ejecting liquid droplets toward the air or liquid. included.

<Example of relationship between elapsed time and discharge speed>
FIG. 7 is a diagram illustrating an example of a relationship between elapsed time and discharge speed according to an embodiment of the present invention. Hereinafter, an example in which the image forming apparatus ejects droplets first, and then the image forming apparatus ejects further droplets, that is, ejects droplets twice will be described. In the following description, the droplet ejected first is referred to as a “first droplet”, and the droplet ejected next to the first droplet is referred to as a “second droplet”.

  In FIG. 7, the vertical axis represents the speed at which the second droplet is ejected (hereinafter referred to as “ejection speed”). FIG. 7 shows a relative value in which the unit system on the vertical axis is “times”. Specifically, when the value of the vertical axis is “1 time”, the respective speeds at which the first droplet and the second droplet are ejected are equal.

  In FIG. 7, the horizontal axis indicates the time from when the first droplet is ejected until the second droplet is ejected (hereinafter referred to as “elapsed time”). In FIG. 7, the unit system on the horizontal axis is “microseconds”. The unit system on the horizontal axis is variable depending on the design of the ejection head.

  When the first droplet is ejected, residual vibration often occurs. The discharge speed changes due to the residual vibration. On the other hand, when time passes, the residual vibration is attenuated. For this reason, in order to reduce the influence of the residual vibration, for example, there is a method of discharging the second droplet after the residual vibration is sufficiently attenuated. In FIG. 7, the elapsed time when the residual vibration is sufficiently attenuated is, for example, the first time T1. Hereinafter, an example in which the elapsed time when the residual vibration is sufficiently attenuated is the first time T1 will be described.

  The elapsed time is not limited to the time starting from the timing at which the first droplet is ejected. For example, the start point of the elapsed time may be a timing at which a so-called fine vibration or fine drive that vibrates the discharge head to such an extent that no droplet is discharged. Even if the vibration is such that no droplet is ejected, residual vibration often occurs. Therefore, the elapsed time is set as a time at which a process that is likely to cause residual vibration is performed regardless of whether or not a droplet is ejected.

  Further, in the following description, a waveform including only one so-called leading pulse in one driving cycle will be described as an example. On the other hand, there may be a plurality of pulses. Further, the type of pulse may be a potential fluctuation that generates vibrations that do not push or eject droplets.

  That is, when the second droplet is ejected at the point where the elapsed time becomes the first time T1, the ejection of the second droplet is less affected by the residual vibration. On the other hand, in order to discharge the second droplet after waiting until the elapsed time reaches the first time T1, the timing at which the first droplet is discharged, the timing at which the second droplet is discharged, The space spreads out. That is, if the second droplet is ejected after waiting for the elapsed time to reach the first time T1, the cycle of ejecting each droplet becomes longer. For this reason, waiting for the elapsed time to reach the first time T1 often increases the time required for image formation. Even when the elapsed time reaches the first time T1, there are few cases where the influence of the residual vibration is completely eliminated.

  Therefore, in order to shorten the time required for image formation, it is desirable that the elapsed time is shorter than the first time T1. When the elapsed time is shorter than the first time T1, the cycle for discharging each droplet can be shortened. As a result, the time required for image formation can be shortened, and productivity can be maintained.

  The image forming apparatus according to the present invention is set to discharge droplets in an elapsed time shorter than the first time T1. In FIG. 7, the elapsed time shorter than the first time T1 is, for example, the second time T2 or the third time T3. The relationship shown in the figure differs depending on the specification of the piezoelectric element. In particular, the shape or physical properties of the flow path in the vicinity of the nozzle often has an influence. Therefore, the second time T2 and the third time T3 may be different depending on specifications such as the shapes of the nozzle, the flow path member, the diaphragm member, and the piezoelectric element. Alternatively, the second time T2 and the third time T3 may be different depending on the shape of the nozzle or the flow path.

  The elapsed time that is set is preferably such that the change in the discharge speed is large as in the second time T2 or the third time T3. Like the second time T2 or the third time T3, the point where the change in the discharge speed is large is often less influenced by variations due to the characteristics of the discharge head or the conveyance speed unevenness of the conveyance speed for conveying the recording medium. When the set elapsed time is set to be the second time T2, the third time T3, or the like, the image forming apparatus can reduce the influence of the variation due to the characteristics of the ejection head or the unevenness of the conveyance speed. Hereinafter, an example in which the elapsed time is set to be the second time T2 or the third time T3 will be described.

  FIG. 8 is a diagram illustrating an example of an image to be formed. Hereinafter, an example in which the input data is the illustrated ejection pattern will be described. In this way, when data is input, the ink jet printer forms an image so that an image indicated by the ejection pattern is formed on the recording medium. Hereinafter, a case where an image of lines as illustrated is formed will be described as an example. Specifically, the illustrated line width (hereinafter referred to as “reference line width W”). An example of image formation aiming at a line to be described will be described. In this example, a discharge pattern in which a line having the reference line width W is formed by inputting three times is input. In FIG. 8, first, in the first row L1, droplets are ejected from the respective nozzles to form an image. Next, in the second row L2, droplets are ejected from the respective nozzles to form an image. Subsequently, when droplets are ejected from the nozzles in the second row L2, a line having the reference line width W is formed as an image. As described above, if there is no influence on the image due to the residual vibration, the dots formed by the respective droplets do not overlap or separate from each other, so that the reference line width W is obtained by three ejections. A line is imaged.

  FIG. 9 is a diagram illustrating an example in which overlap occurs due to residual vibration. For example, it is assumed that the elapsed time is set to be the second time T2 (FIG. 7) for forming the image indicated by the ejection pattern shown in FIG. For this setting, the combination of the drive waveform and the drive cycle is determined so that the elapsed time becomes the second time T2. When determined in this way, the ejection speed increases as shown in FIG.

  In FIG. 9, when the first droplet is the first row L1, the second droplet is the second row L2. As shown in the figure, since the ejection speed of the second row L2 is high, even if image formation is performed based on the ejection pattern shown in FIG. In many cases, dots formed in the second line L2 overlap. Therefore, as shown in FIG. 9, the line on which an image is formed has the line width shown (hereinafter referred to as “first line width W1”). As shown in the figure, in the image formation shown in FIG. 9, since the overlap occurs, the first line width W1 becomes narrower than the reference line width W (FIG. 8).

  That is, in the image formation shown in FIG. 9, a line having a narrower line width than the target line width is formed by residual vibration. On the other hand, when the elapsed time is the second time T2, as shown in FIG. 7, the discharge speed is a maximum or a value close to the maximum. For this reason, when the elapsed time is the second time T2, the influence of variations due to the characteristics of the ejection heads or uneven conveyance speed is often stabilized. Thus, if the elapsed time is the second time T2, the discharge speed is often the same or nearly the same value. Therefore, in FIG. 9, if the elapsed time is the second time T2, the image forming apparatus can stably form an image of the line having the first line width W1 as compared with the case where the elapsed time is another elapsed time. it can.

  FIG. 10 is a diagram illustrating an example of an image formed by the first ejection pattern according to an embodiment of the present invention. The illustrated discharge pattern (hereinafter referred to as “first discharge pattern”) is different in that the discharge in the fourth row L4 is further performed on the image shown in FIG. First, in the image formation shown in FIG. 9, that is, the ejection up to the third row L3, a line having the first line width W1 (FIG. 9) narrower than the reference line width W (FIG. 8) is formed. On the other hand, in the first ejection pattern, dots forming the fourth line L4 are image-formed. Therefore, the image forming apparatus has a line width (hereinafter, referred to as “11th line width W1a”) illustrating an 11th line width W1a closer to the reference line width W than the first line width W1 by the first discharge pattern. Image formation is possible. The eleventh line width W1a is a line thicker than the first line width W1.

  In other words, the image forming apparatus can correct the thinning of the line on which the image is formed due to the overlap as shown in FIG. 9 by the fourth line L4. Correction is to increase the number of dots formed by ejection, as shown in the fourth row L4 shown in the figure, based on the ejection pattern. That is, the image forming apparatus can form an image of the eleventh line width W1a closer to the reference line width W than the first line width W1 by the first ejection pattern.

  Further, the ejection pattern may be a pattern that is set so that ejection is performed in advance so as to increase the line width.

  FIG. 11 is a diagram illustrating an example of an image formed by the second ejection pattern according to the embodiment of the present invention. The ejection pattern may be the illustrated ejection pattern (hereinafter referred to as “second ejection pattern”). The second ejection pattern is different from the pattern shown in FIG. 9 in that the dots of the zeroth row L0 are imaged in advance before the first row L1 to the third row L3 are imaged. . Further, the second discharge pattern may be thinned out for each dot as shown in the figure. Note that the thinning may have an interval of 2 dots or more. Further, depending on the image, different thinning intervals such as 1 dot interval, 2 dot interval, and 3 dot interval may be mixed in the ejection pattern.

  As shown in the drawing, when the ejection of the 0th row L0 is performed, the dots of the 1st row L1 are illustrated by the residual vibration due to the ejection of the 0th row L0. Therefore, the image forming apparatus uses the second ejection pattern to change the illustrated line width (hereinafter referred to as “the twelfth line width W1b”) closer to the reference line width W (FIG. 8) than the first line width W1 (FIG. 9). Image formation is possible.

  Specifically, the second ejection pattern is corrected to an ejection pattern in which dots in the 0th row L0 are preliminarily imaged by thinning out every dot as in the first row P1 and the third row P3. The In this example, in the first column P1, the third column P3, etc., the ejection that becomes the 0th row L0 is performed. That is, the second ejection pattern is corrected so that the 01st dot D01 and the 03rd dot D03 are formed in advance. Accordingly, the discharge of the eleventh dot D11 and the thirteenth dot D13 is often affected by the residual vibration due to the discharge of the 01st dot D01 and the 03rd dot D03, respectively. Specifically, due to the residual vibration, the eleventh dot D11 and the thirteenth dot D13 are formed in a direction overlapping with the 01st dot D01 and the 03rd dot D03, respectively. Accordingly, the image forming apparatus can correct the line on which the image is formed with the twelfth line width W1b by the first row L1 to the third row L3. That is, the image forming apparatus can adjust all or part of the line width by the second ejection pattern.

  In this way, the image forming apparatus can improve the line width reproducibility without reducing the image forming speed, that is, the printing speed, depending on the ejection pattern. In addition, the image forming apparatus can correct the ejection pattern and reduce the variation in line width due to variations in ejection head characteristics or drive cycles.

Second Embodiment
The second embodiment can be realized by an image forming apparatus and an ejection head having the same hardware configuration as the first embodiment. Hereinafter, an example using an image forming apparatus and an ejection head having the same hardware configuration as in the first embodiment will be described, and redundant description will be omitted. In the second embodiment, the ejection pattern and the set elapsed time are different from those in the first embodiment.

  Hereinafter, as in the first embodiment, the case where the line shown in FIG. 8 is image-formed, that is, an example in which the image is formed aiming at the line having the reference line width W will be described.

  In the second embodiment, for example, it is assumed that the elapsed time is set to be the third time T3 (FIG. 7). In order to set in this way, the combination of the drive waveform and the drive cycle is determined so that the elapsed time becomes the third time T3. When determined in this way, the discharge speed becomes slow as shown in FIG.

  FIG. 12 is a diagram illustrating an example in which separation occurs due to residual vibration. In FIG. 12, when the first droplet is the first row L1, the second droplet is the second row L2. As shown in the drawing, since the ejection speed of the second row L2 is slow, the dots formed in the second row L2 are often separated from the dots formed in the first row L1. Therefore, in the image formation shown in FIG. 12, the line on which the image is formed has the illustrated line width (hereinafter referred to as “second line width W2”). As shown in the figure, in the image formation shown in FIG. 12, separation occurs, so that the second line width W2 is thicker than the reference line width W (FIG. 8).

  That is, in the image formation shown in FIG. 12, a line having a larger line width than the target line width is formed by residual vibration. On the other hand, when the elapsed time is the third time T3, as shown in FIG. 7, the discharge speed is a minimum or a value close to the minimum. Therefore, when the elapsed time is the third time T3, as in the case of the second time T2, the influence of variations due to the characteristics of the ejection head or unevenness in the conveyance speed is often stabilized. Thus, if the elapsed time is the third time T3, the discharge speed is often the same or nearly the same value. Therefore, in FIG. 12, if the elapsed time is the third time T3, the image forming apparatus can stably form the image with the line having the second line width W2 as compared with the case where the elapsed time is another elapsed time. it can.

  FIG. 13 is a diagram illustrating an example of an image formed by the third ejection pattern according to the embodiment of the present invention. The illustrated ejection pattern (hereinafter referred to as “third ejection pattern”) is different from FIG. 12 in that dots are thinned out for each dot in ejection in the first row L1. That is, the third ejection pattern is corrected so as to thin out the dots in the second row P2 and the fourth row P4 in the ejection in the first row L1. Note that thinning is not limited to each dot, and two or more dots and a plurality of types of thinning may be mixed.

  As shown in the figure, in the third ejection pattern, the 22nd dot D22 and the 24th dot D24 are ejected in the thinned columns, for example, in the second row L2 of the second column P2 and the fourth column P4. Is less affected by residual vibration, and therefore an image is easily formed at the same position as that shown in FIG. In addition, since the dots are thinned out for each dot in the ejection in the first row L1, the line on which the image is formed has the line width shown in the figure (hereinafter referred to as “21st line width W2a”). The 21st line width W2a is substantially closer to the reference line width W (FIG. 8) than the second line width W2 (FIG. 12). In other words, the image forming apparatus can correct the thickening of the line on which the image is formed due to the separation as shown in FIG. 12 by thinning. Thus, the correction is to change the ejection pattern so as to thin out dots formed by ejection as in the first row L1 shown in the figure.

  Therefore, the image forming apparatus can form an image of a line having the 21st line width W2a that is close to the reference line width W by the third ejection pattern.

  In this way, the image forming apparatus can improve the line width reproducibility without reducing the image forming speed, that is, the printing speed, depending on the ejection pattern. In addition, the image forming apparatus can reduce line width variation due to variations in ejection head characteristics or drive cycles.

  The elapsed time is preferably the second time T2 (FIG. 7) at which the discharge speed becomes faster than the third time T3 (FIG. 7) at which the discharge speed becomes slower. When the discharge speed becomes slow, abnormalities such as so-called “bending” or non-discharge without discharging may occur. Therefore, when the elapsed time is set so as to increase the ejection speed and image formation is performed, the image forming apparatus can reduce ejection abnormalities.

<Third Embodiment>
The third embodiment can be realized by an image forming apparatus and an ejection head having the same hardware configuration as the first embodiment. Hereinafter, an example using an image forming apparatus and an ejection head having the same hardware configuration as in the first embodiment will be described, and redundant description will be omitted. Note that the third embodiment is different from the first embodiment in that the size of each dot by the first droplet and the second droplet is considered.

  Hereinafter, as in the first embodiment, the case where the line shown in FIG. 8 is image-formed, that is, an example in which the image is formed aiming at the line having the reference line width W will be described.

  In the third embodiment, the elapsed time is set so that the ejection speed is increased even when the sizes of the dots formed by the first droplet and the second droplet are different. For example, the first droplet is a droplet that forms an image of a large dot (hereinafter referred to as “large droplet”), and the second droplet is a droplet that forms an image of a small dot (hereinafter referred to as “small droplet”). ).

  Thus, even in the case of a combination of a large droplet and a small droplet, the driving waveform and the driving cycle at which the ejection speed becomes a maximum value or a value close to the maximum value as in the case where the elapsed time shown in FIG. Etc. are set. As a result, even when different types of liquid droplets are combined, the discharge speed is increased as in the case where the elapsed time is the second time T2.

  FIG. 14 is a diagram illustrating another example in which overlap occurs due to residual vibration. For example, it is assumed that the discharge speed is set to be high.

  When set in this way, as shown in FIG. 9, since the discharge speed of the second row L2 is fast as shown in FIG. 9, the second row is compared with the dots formed in the first row L1. In many cases, the dots formed by L2 overlap. Therefore, in the image formation shown in FIG. 14, the line on which the image is formed has the illustrated line width (hereinafter referred to as “third line width W3”). As shown in the figure, the image formation shown in FIG. 14 is overlapped, so that the third line width W3 is narrower than the reference line width W (FIG. 8) as in FIG.

  That is, in the image formation shown in FIG. 14, a line having a narrower line width than the target line width is formed by residual vibration. On the other hand, even when different types of droplets are combined, the discharge speed is set to a maximum value or a value close to the maximum value. Therefore, as in the case where the elapsed time is the second time T2 (FIG. 7), the influence of variations due to the characteristics of the ejection heads or unevenness in the conveyance speed is often stabilized. As described above, even when different types of droplets are combined, if the discharge speed is set to a maximum value or a value close to the maximum value, the discharge speed is often the same or close to the same value. Therefore, in FIG. 14, since the discharge speed is set to a maximum value or a value close to the maximum value, the image forming apparatus can stably form a line with the third line width W3. On the other hand, as in the first embodiment, when an image is formed on the dots in the fourth row L4 shown in FIG. 10, the image forming apparatus uses the reference line width W3 from the third line width W3. A line having a line width close to that shown in FIG. 8 can be formed.

  The first droplet is desirably a small droplet.

  FIG. 15 is a diagram illustrating an example of an image formed by an ejection pattern using a droplet or the like according to an embodiment of the present invention. The discharge pattern shown in FIG. 15 is different from FIG. 10 and the like in that the dots formed in the first row L1 are small. That is, when the dot to be increased is small, the width at which the line width increases is often small. Therefore, if the droplet forming the image to be increased is a small droplet, the image forming apparatus can minimize the amount of increase in the line width. On the other hand, the image forming apparatus can form an image with a line having the illustrated line width (hereinafter referred to as “the 31st line width W3a”). The 31st line width W3a is a line width closer to the reference line width W (FIG. 8) than the third line width W3 (FIG. 14). Therefore, the image forming apparatus can form an image of a line having the 31st line width W3a that is close to the reference line width W by the ejection pattern.

  In this way, the image forming apparatus can improve the reproducibility of the line width without reducing the image forming speed, that is, the printing speed. In addition, the image forming apparatus can reduce line width variation due to variations in ejection head characteristics or drive cycles.

<Example of overall configuration>
FIG. 16 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 17 is a schematic diagram illustrating an example of a mechanism portion included in the image forming apparatus according to an embodiment of the present invention. An ink jet printer 500 as an example of the image forming apparatus illustrated in FIG. 16 is a so-called serial type.

  As shown in FIG. 17, the ink jet printer has side plates 221A and side plates 221B on the left and right. A guide lot 231 and a guide lot 232 are installed on the side plate 221A and the side plate 221B. The carriage 30 moves along the guide lot 231 and the guide lot 232 in the y-axis direction (hereinafter referred to as “carriage main scanning direction”) via the timing belt by the main scanning motor.

  The carriage 30 ejects droplets of each color such as yellow (Y), cyan (C), magenta (M), and black (K). In addition, the carriage 30 may be simply referred to as “recording head 234” when a plurality of recording heads 234a and recording heads 234b having the ejection head 209 (FIG. 3) are not distinguished from each other. There is.) As shown in the figure, the carriage 30 is installed such that a plurality of nozzles are arranged in a direction perpendicular to the carriage main scanning direction (hereinafter also referred to as “sub-scanning direction”).

  In the configuration illustrated in FIG. 17, each recording head 234 has two nozzle rows. For example, the recording head 234a has, on one side, a nozzle row that ejects black (K) droplets. The recording head 234a has a nozzle row that discharges cyan (C) droplets on the other side. Similarly, the recording head 234b has a nozzle row that ejects magenta (M) droplets on one side. In addition, the recording head 234b has a nozzle row that discharges yellow (Y) droplets on the other side.

  The carriage 30 also supplies a head tank 235a and a head tank 235b for supplying ink liquids of the respective colors to the nozzle rows of the recording head 234 (hereinafter, when the head tank 235a and the head tank 235b are not distinguished from each other) It may be referred to as “head tank 235”). A supply tube 236 for each color is connected to the head tank 235. Ink liquid is supplied to the head tank 235 from the cartridges 210k, 210c, 210m, and 210y of each color via the supply tube 236.

  On the other hand, as illustrated in FIG. 16, the ink jet printer 500 includes a paper feed tray 250. The paper feed tray 250 has a paper mounting portion 241 such as a pressure plate. In addition, a sheet 242 as an example of a recording medium is placed on the sheet loading unit 241. In this way, the paper feed tray 250 becomes a paper feed unit that supplies the paper 242.

  Then, the sheets 242 are separated from the sheet loading unit 241 one by one and supplied. For example, as illustrated, the inkjet printer 500 includes a paper feed roller 243 such as a half-moon roller. A separation pad 244 is provided at a position facing the paper feed roller 243. The separation pad 244 is made of a material having a large friction coefficient.

  In order to convey the paper 242 from the paper supply unit to the lower side of the recording head 234, a guide member 245 for guiding the paper 242 is provided. Similarly, in order to convey the paper 242 to the lower side of the recording head 234, a counter roller 246, a conveyance guide member 247, a pressing member 248 having a tip pressure roller 249, and the like are provided.

  In addition, a transport belt 251 and the like are provided to electrostatically attract the transported paper 242 and transport it to a position facing the recording head 234. The transport belt 251 is a so-called endless belt or the like. The conveyor belt 251 is bridged between the conveyor roller 252 and the tension roller 253. As a result, the transport belt 251 circulates in the belt transport direction (sub-scanning direction). A charging roller 256 is provided for the transport belt 251. The charging roller 256 charges the surface of the conveyance belt 251. As illustrated, the charging roller 256 is provided so as to contact the surface of the transport belt 251. Further, the charging roller 256 rotates as the conveyance belt 251 rotates.

  The conveyance belt 251 rotates according to the rotation of the conveyance roller 252 when the conveyance roller 252 is rotated by the sub-scanning motor. Therefore, the conveyance belt 251 moves around in the belt conveyance direction by the sub-scanning motor.

  Next, image formation is performed on the paper 242 by the recording head 234 or the like. After image formation is performed by the recording head 234 and the like, the paper 242 is discharged. A paper discharge unit that discharges paper is realized by a separation claw 261 that separates the paper 242 from the conveyance belt 251, a paper discharge roller 262, a paper discharge roller 263, a paper discharge tray 255, and the like.

  Note that the inkjet printer 500 may include a duplex unit 271 and the like on the back surface. The duplex unit 271 is a detachable unit or the like. The duplex unit 271 reverses the paper 242 sent from the transport belt 251 and feeds it again between the counter roller 246 and the transport belt 251. The illustrated configuration is an example in which the upper surface of the duplex unit 271 is the manual feed tray 272.

  Returning to FIG. 17, the maintenance / recovery mechanism 281 is installed on one side (right side in the drawing) of the range scanned by the carriage 30. The maintenance / recovery mechanism 281 is a mechanism for maintaining and recovering the state of each nozzle of the recording head 234. It is assumed that no image is formed on the recording medium at the position where the maintenance / recovery mechanism 281 is installed. Hereinafter, an area where image formation is not performed on the recording medium is referred to as a “non-printing area”.

  The maintenance / recovery mechanism 281 includes a cap member (hereinafter referred to as “cap”) 282a and a cap member 282b (hereinafter simply referred to as “cap 282” when the cap 282a and the cap 282b are not distinguished from each other). It is done. The cap 282 is used for capping each nozzle surface of the recording head 234.

  The maintenance / recovery mechanism 281 includes a wiper blade 283. The wiper blade 283 is a blade member for wiping each nozzle surface. Further, the maintenance / recovery mechanism 281 is provided with an idle discharge receptacle 284. The idle ejection receptacle 284 receives droplets ejected by so-called idle ejection that ejects droplets that are not used for image formation in order to discharge the thickened recording liquid.

  The non-printing area is provided with an idle discharge receptacle 288 on the other side where the maintenance / recovery mechanism 281 is installed. The idle discharge receiver 288 is provided with an opening 289.

  In the image forming apparatus as described above, as shown in FIG. 16, the paper 242 is separated and fed from the paper feed tray 250 one by one. Next, the fed paper 242 is sent between the counter roller 246 and the conveyance belt 251 by the guide member 245. Subsequently, the sheet 242 is guided by the conveyance guide member 247, and the sheet 242 is pressed against the conveyance belt 251 by the tip pressure roller 249.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256. That is, an alternating voltage is applied to the charging roller 256. By this application, the conveying belt 251 is alternately charged in a strip shape with a predetermined width in the sub-scanning direction, that is, plus and minus in an alternating charging voltage pattern. As described above, when the paper 242 is transported on the transport belt 251 in which plus and minus are alternately charged in a band with a predetermined width, the paper 242 is attracted to the transport belt 251. Further, the paper 242 is transported in the sub-scanning direction by the transport belt 251.

  The carriage 30 (FIG. 3) moves relative to the conveyed sheet 242. Further, the carriage 30 drives the recording head 234 based on the image signal. As a result, droplets are ejected onto the paper 242 and image formation for one line is performed. Next, the inkjet printer 500 conveys a predetermined amount of paper 242. Similarly, droplets are ejected onto the paper 242 and image formation for one line is performed. When a recording end signal or a signal indicating that the trailing edge of the paper 242 has reached the recording area is received, the ink jet printer 500 ends the image formation and discharges the paper 242 to the paper discharge tray 255 or the like.

  Further, the image forming apparatus may be an apparatus having an overall configuration as illustrated in FIG.

  FIG. 18 is a schematic diagram illustrating an example of another overall configuration of an image forming apparatus according to an embodiment of the present invention. An ink jet printer 501 as an example of the image forming apparatus illustrated in FIG. 18 is a so-called full line type head. The ink jet printer 501 includes an image forming unit 601 and a transport mechanism 604 that transports paper. The ink jet printer 501 has a paper feed tray 603 on which a plurality of paper sheets 602 are placed.

  First, the paper 602 is taken from the paper feed tray 603. Next, image formation is performed by the image forming unit 601 on the paper 602 transported by the transport mechanism 604. Thereafter, the sheet 602 is discharged to a discharge tray 605.

  The image forming unit 601 includes a liquid tank that stores a liquid serving as a recording liquid. The image forming unit 601 includes line-type heads 410y, 410m, 410c, and 410k for each color. The line-type heads 410y, 410m, 410c, and 410k for each color have a length corresponding to the length in the paper width direction, that is, the direction orthogonal to the transport direction. Further, the line-type heads 410y, 410m, 410c, and 410k for each color are attached to a head holder or the like. The line-type heads 410y, 410m, 410c, and 410k for each color eject droplets on the paper 602 in the order of black, cyan, magenta, and yellow from the upstream side in the transport direction. The line heads 410y, 410m, 410c, and 410k for each color may be a single head in which a plurality of nozzles that eject droplets of each color are arranged at a predetermined interval. Further, the line-type heads 410y, 410m, 410c, and 410k for each color may have a configuration in which the head and the cartridge are separate.

  Paper sheets 602 placed on the paper feed tray 603 are separated one by one by a paper feed roller 421. Next, the paper 602 is transported to the transport mechanism 604 by the paper feed roller 425.

  The transport mechanism 604 includes a transport belt 433 that is bridged between the driving roller 431 and the driven roller 432. Further, a charging roller 434 that charges the surface of the transport belt 433 is provided.

  Further, the ink jet printer 501 includes a guide member 435 and the like at a position facing the image forming unit 601. Further, the ink jet printer 501 includes a cleaning roller made of a porous material or the like in order to remove ink adhering to the transport belt 433. Furthermore, the ink jet printer 501 has a static elimination roller made of conductive rubber or the like in order to neutralize the paper 602. In addition, the inkjet printer 501 includes a pressing roller that presses the paper 602 against the transport belt 433.

  Further, on the downstream side of the transport mechanism 604, a paper discharge roller 438 and a paper discharge roller 439 for discharging the paper 602 on which image formation has been performed are provided.

  Also in the inkjet printer 501 having such a full-line head, when the conveyance belt 433 is charged and the paper 602 is conveyed to the conveyance belt 433, the paper 602 is attracted to the conveyance belt 433. Next, the sheet 602 is transported by the transport belt 433. Subsequently, the image forming unit 601 forms an image on the paper 602. Thereafter, the sheet 602 is discharged to a discharge tray 605.

  The image forming apparatus according to the present invention may be an apparatus in which a head having a carriage moves as shown in FIGS. 16 and 17, or an apparatus having a full-line type head as shown in FIG. That is, the image forming apparatus according to the present invention may be an apparatus in which the recording medium and the ejection head move relatively.

<Example of overall processing>
FIG. 19 is a flowchart illustrating an example of overall processing performed by the image forming apparatus according to an embodiment of the present invention.

  In step S01, the image forming apparatus inputs data indicating an image formed on the recording medium.

  In step S02, the image forming apparatus sets the elapsed time so that the ejection speed becomes faster or slower. Further, when performing correction, the image forming apparatus changes the ejection pattern so that the number of dots to be formed is increased or the dots to be formed are thinned out.

  In step S03, the image forming apparatus controls the ejection of liquid droplets. Specifically, based on the input data and the set elapsed time, the image forming apparatus controls the ejection of droplets so that image formation is performed.

<Functional configuration example>
FIG. 20 is a functional block diagram showing a functional configuration of an image forming apparatus according to an embodiment of the present invention. As illustrated, the ink jet printer 500 includes a moving unit 100 and a control unit 200.

  The moving unit 100 relatively moves the recording medium and the ejection head. The moving unit 100 is realized by, for example, the main scanning motor 40 (FIG. 3). When the elapsed time fluctuates, the speed of the moving unit 100 is determined so that the dot arrangement resolution becomes a preset resolution such as “1200 dpi”.

  Based on the input data, the control unit 200 discharges droplets onto the recording medium and controls so that a plurality of dots are arranged within a predetermined time. In addition, the control unit 200 sets a discharge pattern in a relatively moving direction. That is, the relatively moving direction is a direction that can be corrected so that the line on which the image is formed becomes thicker or thinner. For example, the relative moving direction is the y-axis direction in FIG. Note that the control unit 200 is realized by, for example, the CPU 201 (FIG. 3) or the like.

  The image forming apparatus scans, for example, an ejection head or the like by the moving unit 100 based on a preset resolution (1200 dpi or the like) regardless of an image to be formed. Therefore, the time required for the image forming apparatus to form an image is determined by the speed at which the ejection head moves, the so-called ejection cycle.

  On the other hand, if a droplet is ejected after waiting for the residual vibration to settle, it is often necessary to lengthen the ejection cycle. On the other hand, the image forming apparatus controls the control unit 200 so that a plurality of dots are arranged within a predetermined time. In this way, unlike the case where droplets are ejected after waiting for the residual vibrations to settle as shown in FIG. 7, there is little need to lengthen the ejection cycle. Therefore, the time required for image formation can be shortened as compared with the case where droplets are ejected after waiting for the residual vibration to settle. Therefore, the image forming apparatus can maintain productivity in image formation. Further, the image forming apparatus can reduce the influence of residual vibration by correction or the like.

  The image forming apparatus according to the present invention can be applied to, for example, an apparatus having a single function of a printer, a facsimile, or a copy. In addition, the image forming apparatus according to the present invention can be applied to a multifunction machine having a plurality of functions such as a printer, a facsimile, and a copy. The droplets are not limited to ink, but may be other types of recording liquids or fixing processing liquids. In other words, the image forming apparatus according to the present invention may be applied to an apparatus that ejects liquid droplets other than ink.

  Therefore, the apparatus for ejecting droplets or the apparatus using the unit for ejecting droplets according to the present invention is not limited to forming an image. For example, the formed object may be a three-dimensional structure.

  Furthermore, the recording medium is not limited to paper. The recording medium may be any material that can be adhered to the droplets. For example, the material to which the liquid can be attached is not limited as long as droplets such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or combinations thereof can be attached even temporarily.

  The embodiment according to the present invention may be realized by a program for causing a computer such as an image forming apparatus to perform image formation.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Or it can be changed.

500, 501 Inkjet printer T1 1st time T2 2nd time T3 3rd time

JP-A-11-170524 Japanese Patent No. 4353432 JP 2000-103090 A JP 2010-36447 A Japanese Patent No. 3827042

Claims (11)

An ejection head that ejects droplets to a relatively moving recording medium;
A control unit that performs control to discharge the droplets to the recording medium based on input data;
With
The control unit causes the second droplet to be discharged after discharging the first droplet to be discharged first from among the plurality of droplets discharged from the discharge head or after vibrating the discharge head. A unit for ejecting liquid droplets, characterized in that the elapsed time is set.   The unit for discharging droplets according to claim 1, wherein the control unit varies the elapsed time.   The unit for ejecting droplets according to claim 2, wherein when the elapsed time is varied, the control unit corrects a ejection pattern in which the droplet is ejected onto the recording medium. The control unit varies the elapsed time so that a discharge speed at which the droplets are discharged is increased,
The unit for discharging droplets according to claim 3, wherein the correction is to increase the number of dots to be formed. The control unit varies the elapsed time so that the discharge speed at which the droplets are discharged becomes slow,
The unit for discharging droplets according to claim 3, wherein the correction is thinning out dots to be formed.   The unit for discharging droplets according to claim 4, wherein the control unit is set so that the discharge speed becomes a maximum.   When the size of the dot formed by the first droplet is different from the size of the dot formed by the second droplet, the control unit determines the type of the first droplet and the second droplet. The unit for discharging droplets according to claim 6, wherein the elapsed time is changed based on a combination of types.   The unit for discharging droplets according to any one of claims 2 to 7, wherein the control unit determines a combination of a driving waveform and a driving cycle to vary the elapsed time. A method of discharging droplets performed by a unit that discharges droplets having a discharge head that discharges droplets on a relatively moving recording medium,
A control procedure in which the unit that discharges the droplets performs control to discharge the droplets to the recording medium based on input data;
Have
In the control procedure, of the plurality of droplets ejected from the ejection head, the first droplet ejected first is ejected or the ejection head is vibrated and then the second droplet is ejected. A method for ejecting liquid droplets, characterized in that the elapsed time is set. A program for causing a computer having a discharge head to discharge droplets to execute a method of discharging droplets on a relatively moving recording medium,
A control procedure in which the computer performs control to discharge the droplets to the recording medium based on input data;
Have
In the control procedure, of the plurality of droplets ejected from the ejection head, the first droplet ejected first is ejected or the ejection head is vibrated and then the second droplet is ejected. A program for executing the feature of setting the elapsed time until. An ejection head that ejects droplets to a relatively moving recording medium;
A moving unit that relatively moves the recording medium and the ejection head;
A control unit that performs control to discharge the droplets to the recording medium based on input data;
With
The control unit causes the second droplet to be discharged after discharging the first droplet to be discharged first from among the plurality of droplets discharged from the discharge head or after vibrating the discharge head. A device for ejecting liquid droplets, characterized in that the elapsed time is set.

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