JP4686793B2 - Inkjet recording method and apparatus - Google Patents

Description

  The present invention relates to an ink jet recording method and apparatus, and more particularly, to a so-called shuttle scan method (serial scan method) in which image recording is performed using pigment ink while an ink jet head is reciprocated in a direction orthogonal to a conveyance direction of a recording medium. The present invention relates to an inkjet recording method and apparatus.

  2. Description of the Related Art Conventionally, an inkjet head (ink ejection head) in which a large number of nozzles (ink ejection ports) are arranged is arranged, and ink is ejected from the nozzles toward the recording medium while relatively moving the inkjet head and the recording medium. 2. Related Art Inkjet recording apparatuses (inkjet printers) that form images on a recording medium by ejecting them as droplets are known.

  Conventionally, various methods are known as ink ejection methods in such an ink jet recording apparatus. For example, the diaphragm constituting a part of the pressure chamber (ink chamber) is deformed by deformation of the piezoelectric element (piezoelectric ceramic) to change the volume of the pressure chamber, and when the volume of the pressure chamber is increased, Ink is introduced into the pressure chamber, and when the volume of the pressure chamber is reduced, the ink is ejected as droplets from the nozzle, or the ink is heated to generate bubbles and the expansion energy when the bubbles grow. A thermal ink jet method for discharging is known.

  In an image forming apparatus having an ink discharge head such as an ink jet recording apparatus, ink is supplied from an ink tank for storing ink to an ink discharge head via an ink supply path, and the ink is discharged by the above various discharge methods. However, it is necessary to discharge stably so that the discharge amount, discharge speed, discharge direction, and shape (volume) of the discharged ink are always constant.

  However, during printing, since the nozzle of the ink ejection head is always filled with ink so that printing is immediately executed when a printing instruction is given, the ink in the nozzle is exposed to air. Ink from nozzles that are not ejected for a long period of time may dry out, resulting in a high ink viscosity or nozzle clogging. Such a thickening at the ink meniscus portion of the nozzle may cause ink ejection failure. In addition, foreign matter such as dust or bubbles mixed in the ink supply path or the like may accumulate, and the ink supply may be shut off, resulting in ejection failure.

  Therefore, in the past, with respect to the thickening of the ink in the meniscus portion of the nozzle, which causes the discharge failure of the ink and the non-discharge of the ink, a purge that forcibly discharges the thickened ink to the outside of the head periodically ( Recovery processes such as spitting, preliminary discharge) and suction have been performed.

  In this suction recovery process, the nozzle surface of the ink jet head is covered with a cap, and ink in the ink jet head is forcibly sucked by a pump. Immediately after sucking, the ink discharged into the cap by suction is the nozzle. It may remain on the surface or may flow back into the inkjet head. Therefore, preliminary discharge is performed after the suction recovery process.

For example, in an ink jet recording apparatus that forms an image using an ink jet head having at least two types of nozzles that discharge with different ink discharge amounts, a large nozzle row and a small nozzle row, the large nozzle row is ejected at the time of preliminary ejection after maintenance suction. By increasing the number of discharges from the small nozzles or increasing the discharge frequency of the large nozzles, the floating mist is reduced and the time required for preliminary discharge after suction is shortened. Is known (see, for example, Patent Document 1).
JP 2004-98626 A

  However, in Patent Document 1, the large nozzle and the small nozzle after the suction recovery process for the purpose of shortening the time required for the preliminary discharge after the suction and preventing the occurrence of floating mist during the preliminary discharge. Although the technology related to the control of the preliminary ejection of the nozzle is disclosed, there is no description about purging (preliminary ejection) during the recording scan, and particularly when using pigment ink, in order to improve the ejection stability, Control of preliminary ejection during recording becomes a problem.

  The present invention has been made in view of such circumstances. In addition to shortening the preliminary discharge time and preventing floating mist, the discharge stability and non-discharge suppression are achieved to ensure stable high-quality printing and reliability. It is an object of the present invention to provide an ink jet recording method and apparatus that can be used.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a recording head having a large nozzle and a small nozzle that communicate with a common ink flow path and eject ink with different ink ejection amounts. An ink jet recording apparatus that performs image recording in one direction or both directions using ink with pigment as a color material while performing bidirectional scanning in a direction substantially perpendicular to the transport direction, and detecting ink type When discharging ink liquid not related to image recording at a specific position outside the image recording area at a specific timing during image recording, the discharge control from the large nozzle and the small nozzle is performed as described above. when the pigment particle size in a dispersed state in said ink ink type detecting unit detects that the more particles 110nm of 5 vol% or less of the ink, the large nozzles and the small In the case of an ink that is simultaneously ejected from a nozzle and has more than 5 vol% of particles having a pigment particle size of 110 nm or more in a dispersed state in the ink and 5 vol% or less of particles having a pigment particle size of 150 nm or more, The number of discharges from the large nozzle is increased more than the number of discharges from the small nozzle, the discharge from the large nozzle is performed before the discharge from the small nozzle, or the discharge frequency from the large nozzle is set to There is provided an ink jet recording apparatus characterized in that at least one of the control is performed so as to make the discharge frequency higher than the small nozzle .

As a result, it is possible to efficiently refresh the old ink in the common liquid chamber at the time of preliminary ejection, in particular , to improve ejection stability of small nozzles and to suppress non-ejection, and to achieve stable high-quality printing and reliability. Securement is possible.

Similarly, in order to achieve the above-mentioned object, the invention according to claim 2 includes a recording head having a large nozzle and a small nozzle that communicate with a common ink flow path and eject ink with different ink ejection amounts. An ink jet recording method for recording an image in one direction or in both directions using an ink with a pigment as a color material while performing bidirectional scanning in a direction substantially orthogonal to the conveyance direction of the recording medium, When the ink liquid not related to image recording is ejected at a specific position outside the image recording area at a specific timing, the particle diameter of the pigment dispersed in the ink is detected, and the ink is dispersed in the ink. When the particle size of the pigment particle size is 110 nm or more is 5 vol% or less, the face is discharged simultaneously from the large nozzle and the small nozzle and is dispersed in the ink. In the case where the number of particles having a particle size of 110 nm or more is more than 5 vol% and the particle size of the pigment having a particle size of 150 nm or more is 5 vol% or less, the number of discharges from the large nozzle is more than the number of discharges from the small nozzle. Or at least one of the discharge from the large nozzle is performed before the discharge from the small nozzle or the discharge frequency from the large nozzle is controlled to be higher than the discharge frequency from the small nozzle. An inkjet recording method characterized by performing any one of the controls is provided.

As a result, it is possible to efficiently refresh the old ink in the common liquid chamber at the time of preliminary ejection, in particular , to improve ejection stability of small nozzles and to suppress non-ejection, and to achieve stable high-quality printing and reliability. Securement is possible.

  As described above, according to the present invention, it is possible to efficiently refresh the old ink in the common liquid chamber at the time of preliminary ejection, improve ejection stability, suppress non-ejection, and achieve stable high image quality. Printing and reliability can be ensured.

  Hereinafter, an inkjet recording method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view showing a schematic configuration of a main part of an embodiment of an ink jet recording apparatus according to the present invention.

  As shown in FIG. 1, the ink jet recording apparatus 1 according to the present embodiment records along a direction (indicated by an arrow B in the drawing) substantially orthogonal to the conveyance direction (indicated by an arrow A in the drawing) of the recording paper 10. This is an image recording apparatus of a shuttle scan system (serial scan system) that records an image by causing the head 12 to scan bidirectionally (while reciprocating).

  The recording paper 10 is supplied below the recording head 12 by a paper feed roller 16 driven by a paper feed motor 14 such as a stepping motor. The recording paper 10 is conveyed in the direction indicated by the arrow A (sub-scanning direction) while maintaining flatness while being supported by a paper holding roller 18 disposed opposite to the paper feeding roller 16 and the recording head 12. Is done. At this time, in order to improve the flatness of the recording paper 10, it is preferable to provide a platen plate that supports the recording paper 10 from the lower side between the paper supply roller 16 and the paper holding roller 18.

  The recording head 12 is mounted on a carriage 22 that can reciprocate in a direction indicated by an arrow B in the drawing along a guide shaft 20 installed across the recording paper 10 in the width direction in a direction substantially perpendicular to the conveyance direction of the recording paper 10. It is mounted on.

  The carriage 22 is fixed to the timing belt 26 by a belt fixing portion 24. The timing belt 26 is stretched between a driving pulley 28 and a driven pulley 30, and the driving pulley 28 is driven by a main scanning motor 32. By driving the main scanning motor 32, the driving pulley 28 is rotated, whereby the timing belt 26 is rotated so that the carriage 22 is reciprocated in the direction of arrow B in the figure.

  Purge receptacles (caps) 34 and 36 are provided outside the printing area on both sides of the recording paper 10 in the width direction. In particular, the purge receiver 36 provided outside the print area on the right side of the recording paper 10 in FIG. 1 constitutes a recovery mechanism linked to the suction means, as will be described in detail later. During maintenance, the carriage 22 moves to the positions of the purge receivers 34 and 36, and maintenance of the recording head 12 such as purge (preliminary ejection) and suction is performed. A position sensor 38 is provided for detecting that the recording head 12 is at the position (home position) of the purge receiver 36 that constitutes the recovery mechanism.

  An ink type detection unit 39 for detecting the type of ink ejected from the recording head 12 is attached to the recording head 12 on the carriage 22. For example, a memory information reading unit attached to the carriage by attaching a memory storing pigment particle size distribution information in the pigment ink to the ink cartridge or attaching barcode information indicating the particle size distribution information to the ink cartridge The information is read by a bar code reader or the like. The installation position of the ink type detection unit 39 is not limited to this.

  The recording head 12 is mounted on the carriage 22 and reciprocates on the recording paper 10 in the width direction in the direction of arrow B in the figure in accordance with the movement of the carriage 22 to perform bidirectional scanning. At this time, the recording head 12 may perform recording in both directions, or may perform recording in only one direction.

  FIG. 2 shows a plan view of the recording head 12. In FIG. 2A, a yellow head 12Y that ejects yellow (Y) ink, a magenta head 12M that ejects magenta (M) ink, a cyan head 12C that ejects cyan (C) ink, and black (K) ) Are ejected so that the nozzle rows are substantially perpendicular to the moving direction of the recording head 12 indicated by the arrow B1.

  On the other hand, when recording is performed in both directions, the head groups 12-1 and 12-2 each having four heads 12Y, 12M, 12C, and 12K are connected to the recording head 12 as shown in FIG. When the recording head 12 scans in the arrow B1 direction, recording is performed using the head group 12-1, and the recording head 12 scans in the arrow B2 direction. May be recorded using the head group 12-2.

  Further, the recording head 12 of the present embodiment has a large nozzle with a large discharge amount and a small nozzle with a small discharge amount. Here, it is assumed that the discharge amount of the large nozzle is about 5 to 10 [pl], and the discharge amount of the small nozzle is about 1 to 2 [pl]. In the present embodiment, the large nozzle increases the nozzle diameter, and the small nozzle decreases the nozzle diameter, thereby forming a difference in the large and small discharge amounts.

  FIG. 3 shows an example of a nozzle arrangement corresponding to the recording head 12 shown in FIG. In FIG. 3A, a large nozzle diameter is provided on one side of a common liquid chamber 40 provided so as to extend in a direction substantially perpendicular to the scanning direction (main scanning direction) of the recording head 12 indicated by an arrow B. A nozzle 42 is disposed, and a small nozzle 44 having a small nozzle diameter is disposed on the other side of the common liquid chamber 40.

  In the example shown in FIG. 3B, large nozzles 42 having large nozzle diameters and small nozzles 44 having small nozzle diameters are alternately arranged on both sides of the common liquid chamber 40.

  As described above, in any of the examples shown in FIG. 3, the ink is supplied to the large nozzle 42 and the small nozzle 44 of the same color from the same common liquid chamber 40 for each color so The road is common.

  Further, in the present embodiment, recording is performed using pigment ink. In particular, the particle size information is detected from the type of pigment ink, and purging or the like is performed according to the detected particle size information of the pigment ink. The control method of the preliminary discharge is changed. Although details will be described later, for example, when the pigment particle size is fine, purging or preliminary discharge is simultaneously performed from the large nozzle and the small nozzle, and when the pigment particle size is large, the large nozzle is smaller. It is intended to discharge before or more than the nozzle.

  FIG. 4 shows a cross-sectional view of the head (12Y, 12C, 12M, 12K). Since the structures of the heads 12Y, 12C, 12M, and 12K are all the same, the reference numerals are common here and the heads 50 are represented. Also, the large nozzle 42 and the small nozzle 44 described above are simply represented as nozzles 51 without being distinguished here.

  As shown in FIG. 4A, the head 50 is formed by a pressure chamber 52 communicating with a nozzle 51 for ejecting ink. The pressure chamber 52 is provided with an electrothermal conversion element 54, which serves as a recording signal. By applying an electrical pulse, thermal energy is applied to the ink, and the bubble pressure generated at the time of film boiling in the ink is used for ejecting the ink droplets.

FIG. 4B shows a sectional view of the large nozzle, the small nozzle, and the common liquid chamber (common flow path). The head 50 is formed by a large nozzle 42 for discharging ink, a small nozzle 44, and electrothermal conversion elements 54a and 54b below the pressure chambers 52a and 52b. The large nozzle 42 has an opening area of about 200 μm ² and is small. The opening area of the nozzle is about 120 μm ² . The pressure chambers 52a and 52b communicate with a common liquid chamber (common flow path) 55 for supplying ink via the supply ports 53a and 53b. Each of the nozzles 42 and 44 is prepared so that new ink is filled into the pressure chambers 52a and 52b from the common liquid chamber (common flow path) 55 through the supply ports 53a and 53b in preparation for the next discharge after the ink discharge. It has become.

  In this embodiment, a thermal method is used in which droplets are discharged using thermal energy, but other methods such as a piezo method in which droplets are discharged by the deformation pressure of a piezoelectric element may be used.

  FIG. 5 shows a schematic configuration of an ink supply system in the inkjet recording apparatus 1 of the present embodiment.

  In FIG. 5, an ink tank 60 is a base tank for supplying ink to the head 50. The ink tank 60 may be mounted on the carriage 22 shown in FIG. 1 so as to reciprocate together with the carriage 22. Alternatively, the ink tank 60 may be disposed outside the carriage 22 and attached to the head 50 by an ink supply pipe formed of a flexible tube or the like. Ink may be supplied. In the form of the ink tank 60, there are a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink decreases. When the ink type is changed according to the usage, the cartridge method is suitable.

  At this time, the ink type detection unit 39 detects the ink type. This ink type detection method is not particularly limited. For example, the ink type may be detected by identifying the ink type information with a barcode or the like. As will be described in detail later, ejection control is performed according to the detected ink type.

  A filter 62 is provided in the middle of the conduit connecting the ink tank 60 and the head 50 to remove foreign substances and bubbles. Although not shown in FIG. 5, a configuration in which a sub tank is provided in the vicinity of the head 50 or integrally with the head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head 50.

  Further, the inkjet recording apparatus 1 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A. .

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 50 as necessary. . Here, the cap 64 represents what is represented by the purge receivers 34 and 36 in FIG.

  The cap 64 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The lifting mechanism is configured to cover the nozzle region of the nozzle surface 50 </ b> A with the cap 64 by raising the cap 64 to a predetermined raised position when the power is turned off or waiting for printing.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink discharge surface (nozzle surface 50A) of the head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matter adheres to the nozzle surface 50A, the nozzle surface 50A is wiped by sliding the cleaning blade 66 on the nozzle surface 50A to clean the nozzle surface 50A.

  During printing (recording) or standby, when a specific nozzle 51 is used less frequently and the ink viscosity in the vicinity of the nozzle 51 rises, a cap (purge receiver) is used to discharge the deteriorated ink due to the increased viscosity. ) Predischarge (purge) is performed toward 64.

  Further, when bubbles are mixed in the ink in the head 50 (ink in the pressure chamber 52), the cap 64 is applied to the head 50, and the ink in the pressure chamber 52 (ink in which bubbles are mixed) is sucked by the suction pump 67. The ink removed and sucked and removed is sent to the collection tank 68.

  This suction operation is also performed when the ink is initially loaded into the head 50 or when the ink is used after being stopped for a long time, and the deteriorated ink solidified by increasing the viscosity is sucked and removed.

  That is, if the head 50 does not discharge for a certain period of time, the ink solvent in the vicinity of the nozzles evaporates and the viscosity of the ink in the vicinity of the nozzles increases, and the discharge electrothermal conversion element 54 operates. Ink is no longer ejected from the nozzle 51. Therefore, before this state is reached (within the viscosity range in which ink can be ejected by the bubble pressure generated by the electrothermal conversion element 54), the electrothermal conversion element 54 is operated, and the cap (purge receiver) 64 is attached. “Preliminary ejection” is performed to eject ink in the vicinity of the nozzle whose viscosity increases toward the nozzle. Further, after the dirt on the nozzle surface 50A is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, foreign matter is prevented from being mixed into the nozzle 51 by this wiper rubbing operation. Also, preliminary discharge is performed. This preliminary discharge may also be called “empty discharge”, “purge”, “spitting”, or the like.

  In addition, if bubbles are mixed in the nozzle 51 or the pressure chamber 52 or if the viscosity of the ink in the nozzle 51 exceeds a certain level, ink cannot be ejected by the preliminary ejection. Do.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 52, or when the ink viscosity in the nozzle 51 rises to a certain level or more, ink is ejected from the nozzle 51 even if the pressure generating means is operated. become unable. In such a case, an operation in which the cap 64 is applied to the nozzle surface 50A of the head 50 and the ink in which the bubbles in the pressure chamber 52 are mixed or the ink having increased viscosity is sucked by the suction pump 67 is performed.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. Note that the cap 64 described with reference to FIG. 5 functions not only as a suction unit but also as a purge receiver that receives ink ejected by preliminary ejection.

  Further, the inside of the cap 64 may be divided into a plurality of areas corresponding to the nozzle rows by a partition wall, and each partitioned area may be selectively sucked by a selector or the like. For example, the aforementioned large nozzle 42 and small nozzle 44 may be sucked separately.

  FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 1 of the present embodiment.

  The inkjet recording apparatus 1 includes a communication interface 70, a system controller 72, an image memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, a recovery control unit 90, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB, IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 86 is taken into the inkjet recording apparatus 1 via the communication interface 70 and temporarily stored in the image memory 74. The image memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The image memory 74 is not limited to a memory composed of semiconductor elements, and a magnetic medium such as a hard disk may be used.

  The system controller 72 is a control unit that controls each unit such as the communication interface 70, the image memory 74, the motor driver 76, the heater driver 78, the recovery control unit 90, and the head driver 84 via the print control unit 80. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the image memory 74, and the like, as well as a transport system motor 88 and heater 89. A control signal for controlling is generated. Further, a detection signal from the ink type detection unit 39 is input to the system controller 72. As will be described in detail later, purging, preliminary ejection, and the like are controlled through the recovery control unit 90 in accordance with the detection signal. The recovery control unit 90 is for controlling the suction pump 67, the cap 64, and the cleaning blade 66 for the recovery operation of the head 50 during maintenance.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives a heater 89 for drying the recording paper 10 after recording or adjusting the temperature of the head 50 in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processes such as processing and correction for generating a signal for printing (recording) control from image data in the image memory 74 under the control of the system controller 72. The control unit supplies the generated print control signal (print data) to the head driver 84. Necessary signal processing is performed in the print control unit 80, and the number of ink droplets ejected from the head 50 and ejection timing are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 6, the image buffer memory 82 is shown in a form associated with the print control unit 80, but it can also be used as the image memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with a single processor.

  The head driver 84 drives the bubble pressure generating means of each color head 50 based on the print data given from the print controller 80. The head driver 84 may include a feedback control system for keeping the driving condition of the head 50 constant.

  Hereinafter, the operation of the present embodiment will be described. In this embodiment, in particular, the particle size distribution information is detected from the type of pigment ink, and the purging and preliminary ejection control method is changed according to the detected particle size distribution information of the pigment ink. In short, when most of the pigments in the ink are fine particle size pigments, purging or preliminary ejection is performed simultaneously from a large nozzle and a small nozzle, and when a large particle size pigment particle size is included. In order to ensure the reliability by performing stable high-quality printing by improving the ejection stability of small nozzles and suppressing non-ejection, especially by ejecting large nozzles before or more than small nozzles. It is possible.

  In addition, the present applicant changed the purge control of inks having different pigment particle size distributions, and evaluated the ejection stability of the small nozzles and the degree of occurrence of non-ejection, whereby the pigment particle size distribution in the pigment inks was evaluated. It was experimentally confirmed that by adopting a purge control method suitable for the above, it is possible to achieve ejection stability and non-ejection suppression of a small nozzle. The results are shown in FIGS.

  In this experiment, using a recording head having a large nozzle and a small nozzle capable of ejecting pigment ink, the recording head is scanned in the main scanning direction to draw a line on a predetermined recording medium (inkjet photographic paper), Nozzle ejection and line bending were confirmed from the recorded image.

The ink used in this experiment was 5% by weight of pigment, 10% by weight of diethylene glycol, 10% by weight of glycerin, 1% by weight of a surfactant, and a residual water. In addition, due to the difference in the particle size distribution of the pigment ink, in particular, the difference in the degree of inclusion of large particles in the particle size distribution, the appearance of non-ejection of the nozzle and the direction stability of the liquid ejection change, so Different particle size distributions were prepared. Among the pigment particle size distributions, in particular, the degree of distribution of the large size pigment particle size is a particular problem, so the volume distribution of the particle size distribution is The particle diameter value that cumulatively reaches ₉₅ vol% from the smaller particle diameter side was expressed as “D ₉₅ ” and used as the index value of the ink used.

The measurement conditions with the particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.) are as follows: volume distribution display, particle refractive index = 1.51, particle permeability = permeation, particle shape = non-spherical, solvent = water, The measurement was performed at a temperature of 25 ° C. using a 100-fold diluted water with the solvent refractive index = 1.333, the filter = standard, and the sensitivity = standard. The value of “D ₉₅ ” used was a particle size value (nm) displayed as a cumulative 95% result among a series of measured values displayed as a measurement result.

  In the experiment, for each of the 100 large and small nozzles in the head, after drawing a line by 5000 ejections while scanning, the line was left for 10 seconds, purged, scanned again, and 5000 lines were ejected to perform line drawing. The small nozzle discharge failure and line bending during line drawing were evaluated.

  Regarding discharge failure, the number of discharge nozzles in 100 small nozzles was counted, and 99% to 100% discharge was evaluated as ◯, 95% to 98% discharge as Δ, and less than 95% discharge as X. As for line bending, a line whose landing position is shifted by 10 μm or more is regarded as line bending, and among the line drawing by 100 small nozzles, the number of nozzles that do not cause line bending is counted, and 90% to 100% is not bent. The state of ◯, the state of 60% or more and less than 90% without bending was judged as Δ, and the state of less than 60% without bending was judged as ×.

The purge control method is control A in which large nozzle discharge is discharged before small nozzle discharge and discharge is performed 100 times each for large and small nozzles, and control for discharging large nozzles three times more than small nozzles ( Control B was set to discharge large nozzles 150 times and small nozzles 50 times). In FIG. 7, “the size (D ₉₅ ) corresponding to ₉₅ vol% accumulated from the smallest pigment particle size distribution is less than 150 nm (particles having a particle diameter of 150 nm or more are 5 vol% or less)”, Under the condition of discharging large nozzles in advance or discharging many from large nozzles, no discharge failure occurs and line bending is reduced.

In FIG. 8, the purge control method is different, and control for discharging 100 times at the same time for the large and small nozzles is defined as control C. In the case of Control C, the occurrence of undischarge occurred under the condition that “the size corresponding to ₉₅ vol% accumulated from the smallest pigment particle size distribution (D ₉₅ ) is less than 110 nm (particles having a particle size of 110 nm or more are 5 vol% or less)”. There is less line bending.

According to the experiment shown in FIG. 7 and FIG. 8, the pigment particle size is “the size corresponding to ₉₅ vol% accumulated from the smaller pigment particle size distribution (D ₉₅ ) is less than 150 nm (particles having a particle size of 150 nm or more are 5 vol. In the case of “% or less” ”, it was found that by setting the purge control to“ discharge the large nozzle first or discharge a large amount from the large nozzle ”, no discharge failure occurs and the line bending is reduced. Furthermore, in the case of a fine pigment having a pigment particle diameter of less than D ₉₅ = 110 nm, it has been found that even when purge control is performed in which the same number of nozzles are simultaneously ejected at large and small nozzles, there is no effect on ejection stability and non-ejection suppression.

  The operation of this embodiment will be described below along the flowcharts of FIGS.

  FIG. 9 shows the overall control of purging and preliminary discharge in this embodiment, and particularly the control when the pigment particle size is large. FIG. 10 shows the control in the case where the purging and preliminary discharge pigment particle size is small according to the present embodiment.

  First, in step S100 in FIG. 9, the ink type used in the inkjet recording apparatus 1 is detected. This is performed by the ink type detection unit 39. The detected ink type is sent to the system controller 72 to determine the pigment particle size distribution.

  Next, in step S102, it is determined whether or not the pigment particle size distribution is in the first range. This determination is made based on whether or not particles having a pigment particle size of 110 nm or more are 5 vol% (volume%) or less. When this condition is satisfied, there are not many particles having a pigment particle size of 110 nm or more, and most pigment particle sizes are smaller than 110 nm. At this time, the pigment ink is an ink having a finer pigment particle size. . In such a case, the process proceeds to the flowchart of FIG. The processing when the pigment particle size is small will be described later.

  When the pigment particle diameter is not in the first range in the determination of step S102, that is, when the ratio of particles having a pigment particle diameter of 110 nm or more is larger than 5 vol%, the pigment particle diameter is in the second range in next step S103. It is determined whether or not This determination is made based on whether or not the number of particles having a pigment particle size of 110 nm or more is more than 5 vol%, and the number of particles having a pigment particle size of 150 nm or more is 5 vol% or less. The case where the pigment particle size is in the second range is a case where there are more than 5 vol% of particles having a pigment particle size of 110 nm or more, but most of them are in the range of 150 nm or less. In addition, in the case of ink that does not match the first range or the second range, that is, when an ink having a particle size of more than 5% by volume exceeding 150 nm is mounted, non-ejection occurs. A warning is given that there is a possibility that the possibility and drawing quality will be deteriorated, and prompts the user to replace the ink with ink that matches the first range or the second range.

  When the pigment particle diameter is in the second range, the large nozzle is discharged more than the small nozzle in purging or preliminary discharge, or the large nozzle is discharged before the small nozzle. . The example described below with reference to FIG. 7 is an example of control in which a large nozzle is ejected prior to a small nozzle in preliminary ejection.

  When the pigment particle size is in the second range, that is, when the number of particles having a pigment particle size of 110 nm or more is more than 5 vol% and the number of particles having a pigment particle size of 150 nm or more is 5 vol% or less, image formation is first performed in step S104. Start. When image formation is started, the first time measurement and the second time measurement are started in step S106. Here, the first time measurement is for controlling the timing of preliminary discharge (purging), and the second time measurement is for controlling the timing of preliminary discharge after suction.

  In step S108, image output (image recording) is performed. This is because the main scanning motor 32 drives the carriage 22 to reciprocate the recording head 12 in the main scanning direction that is substantially perpendicular to the conveyance direction (sub-scanning direction) of the recording 10. Images are formed by ejecting pigment ink from 12M and 12K onto the recording paper 10, respectively. At this time, as described above, an image may be recorded only when scanning in one direction, or an image may be recorded in both directions.

  While performing image recording in this way, in the next step S110, it is determined whether or not a first time for controlling the preliminary ejection timing during recording has passed a predetermined time. If the first time has elapsed, even if an image is being recorded on one recording paper 10, the image recording is interrupted and the carriage 22 is moved to the purge position in the next step S112. For example, the carriage 22 is moved to the position of a purge receiver 34 provided on the left side in the conveyance direction of the recording paper 10 in FIG. However, at this time, if the carriage 22 is positioned on the right side of the center of the recording paper 10 in the width direction in FIG. 1, the carriage 22 may be moved toward the right purge receiver 36.

  Next, in step S114, the large nozzle 42 is first discharged toward the purge receiver 34 (or the purge receiver 36), and then the small nozzle 44 is discharged in the next step S116 to perform purging.

  After the preliminary ejection from the large nozzle 42 and the small nozzle 44 is completed, in the next step S118, the first timing is reset, the carriage 22 is returned to the position where the image recording is interrupted, and the process returns to step S108 to resume image formation. .

  If it is determined in step S110 that the first time has not yet elapsed (after reset), the process proceeds to the next step S120, where a second time for controlling the preliminary discharge timing after suction is determined. Determine whether the time has passed.

  If it is determined in step S120 that the second time has elapsed, the process proceeds to step S122, the image recording is interrupted, and the carriage 22 is moved to the suction position where the purge receiver 36 shown in FIG. 1 is installed. . In the next step S124, the purge receiver (cap) 36 is brought into close contact with the recording head 12 (head 50), the suction pump 67 is driven, and the ink in the large nozzle 42 and the small nozzle 44 is sucked.

  Next, in step S126, the large nozzle 42 is discharged toward the purge receiver 36. Thereafter, in step S128, the large nozzle 42 is similarly discharged toward the purge receiver 36 from the small nozzle 44.

  In step S130, the second time measurement is reset, the carriage 22 is returned to the position where the image recording is interrupted, and the process returns to step S108 to resume image recording.

  In this way, image recording is continued while repeatedly performing purging during image recording, and a combination of suction and purging. When image data ends in step S132, image recording ends.

  In addition to the preliminary ejection after suction as described above, the ejection amount from the large nozzle 42 is also larger than the ejection amount from the small nozzle 44 when preliminary ejection is performed from the large nozzle 42 and the small nozzle 44 during image recording. It is preferable to perform preliminary discharge control that increases the number of times. Increasing the discharge amount from the large nozzle 42 has a great effect not only in preventing floating mist and shortening the preliminary discharge time, but also in stabilizing discharge and suppressing non-discharge. Since both the large nozzle 42 and the small nozzle 44 are supplied with ink from the same common liquid chamber 40 (55), by increasing the preliminary discharge amount from the large nozzle 42, the old one in the common liquid chamber 40 (55) is used. Ink can be effectively discharged (discharged), and in particular, the discharge characteristics of the small nozzles 44 can be improved.

  Discharge so that the number of discharges from the large nozzle 42 in this preliminary discharge (the number of discharges from one large nozzle 42) is greater than the number of discharges from the small nozzle 44 (the number of discharges from one small nozzle 44). You may make it do. For example, one small nozzle 44 discharges 50 times while one large nozzle 42 discharges 100 times. Thereby, the discharge amount from the large nozzle 42 can be made larger than the discharge amount from the small nozzle 44.

  Further, it is preferable that the discharge is performed so that the discharge frequency from the large nozzle 42 is higher than the discharge frequency of the small nozzle 44 at the time of preliminary discharge. For example, by making the discharge frequency of the large nozzle 42 about 2 to 4 times the discharge frequency of the small nozzle 44, a large amount of old ink in the common liquid chamber 40 (55) can be effectively produced from the large nozzle 42. It is possible to discharge, and the discharge stability can be improved.

  Next, the discharge control when the pigment particle size is in the first range will be described. If it is determined in step S102 of FIG. 9 that the pigment particle size is in the first range, that is, particles having a pigment particle size of 110 nm or more are 5 vol% or less, the processing of the flowchart of FIG. 10 is performed.

  The discharge control in FIG. 10 is a process for an ink whose pigment particle size is reduced to be close to that of a dye ink. In this case, as described below, large and small nozzles are simultaneously purged or pre-discharged.

  First, in step S200 in FIG. 10, image formation is started. When image formation is started, the first time measurement and the second time measurement are started in step S202. Here, the meaning of the first timekeeping and the second timekeeping is the same as the control in FIG. That is, the first time measurement is for controlling the timing of preliminary discharge, and the second time measurement is for controlling the timing of preliminary discharge after suction.

  In step S204, image recording is performed. While performing image recording, next, in step S206, it is determined whether or not a predetermined time has elapsed from the first time measurement. If the first time has elapsed, the image recording is interrupted, and the carriage 22 is moved to the purge position (purge receiver 34 or 36) in the next step S208.

  In step S210, the large nozzle 42 and the small nozzle 44 are simultaneously discharged toward the purge receiver 34 or 36. That is, preliminary ejection is performed by ejecting all nozzles simultaneously.

  In step S212, the first time measurement is reset, the carriage 22 is returned to the position where the image recording is interrupted, and the process returns to step S204 to restart image formation.

  If it is determined in step S206 that the first time has not yet elapsed (after reset), the process proceeds to the next step S214 to determine whether the second time has not elapsed.

If it is determined in step S214 that the second clock has passed the predetermined time, the process proceeds to step S216, where the image recording is interrupted, and the carriage 22 is moved to the position where the purge receiver 36 shown in FIG. In the next step S218, the purge receiver (cap) 36 is brought into close contact with the recording head 12 (head 50), and the suction pump 67 is driven to suck the ink in the large nozzle 42 and the small nozzle 44, that is, all the nozzles. .

  Next, in step S220, discharge is performed from the large nozzle 42 and the small nozzle 44, that is, from all the nozzles toward the purge receiver 36. In step S222, the second timing is reset, the carriage 22 is returned to the position where the image recording is interrupted, and the process returns to step S204 to resume the image recording.

  In this way, image recording is continued while repeatedly performing purging during image recording and a combination of suction and purging. If it is determined in step S224 that the image data has risen, the image recording ends.

  As described above, in the present embodiment, an ink in which the pigment particle size of the pigment ink is miniaturized (the pigment particle size is in the first range) and an ink having a relatively large pigment particle size (the pigment particle size is in the second range). If the pigment particle size is relatively large, for example, control is performed so that the large nozzle is ejected before the small nozzle. By performing control so as to perform buzzing at the same time, it is possible to efficiently improve discharge stability and suppress non-discharge, and to ensure stabilization and reliability of high-quality printing.

  The inkjet recording method and apparatus of the present invention have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. Of course.

1 is a schematic configuration diagram illustrating a main part of an embodiment of an ink jet recording apparatus according to the present invention. 2A and 2B are plan views of the recording head, in which FIG. 3A is an example of a recording head in the case of unidirectional recording, and FIG. 4B is an example of a recording head in the case of bidirectional recording. 3A is a plan view showing an example of a nozzle arrangement of the recording head shown in FIG. 2A, FIG. 2A is a diagram in which large nozzles and small nozzles are arranged in one row, and FIG. They are arranged alternately in one row. (A) And (b) is sectional drawing of a head. 1 is a schematic configuration diagram illustrating an ink supply system of an ink jet recording apparatus according to an embodiment. It is a principal part block diagram which shows the system configuration | structure of the inkjet recording device of this embodiment. It is explanatory drawing which shows the result of the evaluation experiment by a pigment ink. It is explanatory drawing which similarly shows the result of the evaluation experiment by pigment ink. 6 is a flowchart illustrating preliminary discharge control when the pigment particle diameter is relatively large, which is an operation of the ink jet recording apparatus according to the embodiment. It is a flowchart which shows preliminary discharge control when the pigment particle size which is an effect | action of the inkjet recording device of this embodiment is refined | miniaturized.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Recording paper, 12 ... Recording head, 14 ... Paper feed motor, 16 ... Paper feed roller, 18 ... Paper suppression roller, 20 ... Guide shaft, 22 ... Carriage, 24 ... Belt fixing part, 26 ... timing belt, 28 ... drive pulley, 30 ... driven pulley, 32 ... main scanning motor, 34, 36 ... purge receiver, 38 ... position sensor, 39 ... ink type detection unit, 40, 55 ... common liquid chamber, 42 ... large Nozzle, 44 ... small nozzle, 50 ... head, 51 ... nozzle, 52 ... pressure chamber, 53 ... supply port, 56 ... vibrating plate, 57 ... individual electrode, 58 ... piezoelectric body, 60 ... ink tank, 62 ... filter, 64 ... Cap, 66 ... Cleaning blade, 67 ... Suction pump, 68 ... Collection tank, 70 ... Communication interface, 72 ... System controller, 74 ... Image memory, 7 ... motor driver, 78 ... heater driver, 80 ... print control unit, 82 ... image buffer memory, 84 ... head driver, 86 ... host computer, 88 ... motor, 89 ... heater, 90 ... recovery control unit

Claims (2)

The pigment is colored while scanning a recording head that communicates with a common ink flow path and has large nozzles and small nozzles that discharge ink with different ink discharge amounts in a direction substantially perpendicular to the conveyance direction of the recording medium. An ink jet recording apparatus that performs image recording in one direction or both directions using ink as a material,
An ink type detection unit for detecting the ink type;
When discharging ink liquid not related to image recording at a specific position outside the image recording area at a specific timing during image recording, the ink type detection unit relates to the discharge control from the large nozzle and the small nozzle. When the detected particle diameter of the pigment having a particle diameter of 110 nm or more in the ink is 5 vol% or less, the ink is simultaneously ejected from the large nozzle and the small nozzle and is dispersed in the ink. In the case where the number of particles having a pigment particle size of 110 nm or more is more than 5 vol% and the number of particles having a pigment particle size of 150 nm or more is 5 vol% or less, the number of discharges from the large nozzle is more than the number of discharges from the small nozzle. Or the discharge from the large nozzle is performed before the discharge from the small nozzle, or the discharge frequency from the large nozzle An ink jet recording apparatus which is characterized in that one control at least one of which controls to greater than the ejection frequency from the small nozzle. The pigment is colored while scanning a recording head that communicates with a common ink flow path and has large nozzles and small nozzles that discharge ink with different ink discharge amounts in a direction substantially perpendicular to the conveyance direction of the recording medium. An ink jet recording method for performing image recording in one direction or in both directions using ink as a material,
During the image recording, when ejecting ink liquid not related to image recording at a specific position outside the image recording area at a specific timing, the pigment particle size in a dispersed state is detected in the ink, When the particles having a pigment particle size of 110 nm or more in the dispersed state are inks of 5 vol% or less, the pigment particle size in the dispersed state in the ink is simultaneously discharged from the large nozzle and the small nozzle. In the case where the number of particles is more than 5 vol% and the particle diameter of the pigment having a particle diameter of 150 nm or more is an ink of 5 vol% or less, the number of ejections from the large nozzle is increased more than the number of ejections from the small nozzle, or The discharge from the large nozzle is performed prior to the discharge from the small nozzle, or the discharge frequency from the large nozzle is set to be higher than the discharge frequency from the small nozzle. Ink jet recording method and performing one control at least one of which controls to hear.

Images