JP2013111869A - Ink-jet recording device and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when a recording head is driven using an ink-jet recording device equipped with means for preventing ink thickening near a nozzle by minutely vibrating ink meniscus, meniscus is broken by the given minute vibration, and thereby resulting in degradation in discharge stability.SOLUTION: In a recording method for an ink-jet recording device, the vibration repetition for meniscus is set according to the drive frequency of a recording head to such a suitable repetition that degradation in discharge stability resulting from meniscus break is prevented. Thus, satisfactory discharge stability is ensured.

Description

  The present invention relates to an ink jet recording apparatus and a recording method provided with means for giving a fine vibration to an ink meniscus in a nozzle portion of a recording head.

2. Description of the Related Art Conventionally, ink jet recording apparatuses that perform recording on a recording medium by discharging ink droplets from nozzles provided in a recording head are known.
As inkjet recording apparatuses, not only small-sized inkjet recording apparatuses for consumer use but also large-sized inkjet recording apparatuses for industrial use such as textile printing and outdoor advertising are widely used.

  Among these, a large inkjet recording apparatus records on a wide range of recording media, and a recording head mounted on the inkjet recording apparatus is exposed to the atmosphere for a long time because it scans a long distance. When the air is released to the atmosphere, the ink in the vicinity of the nozzles of the recording head may be dried, resulting in thickening and nozzle clogging, which may cause ejection failure.

  As a method of relieving the viscosity increase and nozzle clogging caused by ink drying, the ink and the head near the dried nozzle are given a slight vibration to the ink meniscus to the non-ejection nozzle during the recording operation. There has been proposed a method of stirring the ink in an internal bulk state to prevent ink thickening (see Patent Documents 1 and 2).

  In addition, as a technology that gives the ink meniscus a slight vibration that does not eject ink, it simultaneously consumes a large amount of power by preventing the ink meniscus from causing a slight vibration that does not eject ink to a large number of nozzles. A technique for preventing this is disclosed (see Patent Document 3).

  On the other hand, recent inkjet recording apparatuses are required to improve recording speed in addition to the beauty of recorded images. In general, the beauty of a recorded image is improved by lowering the recording speed. In other words, it is necessary to reduce the drive frequency of the recording head in order to record a beautiful recorded image. Further, in order to improve the recording speed, it is naturally necessary to increase the driving frequency of the recording head. Therefore, from the viewpoint of improving the beauty of the recorded image and the recording speed, an ink jet recording apparatus that includes a plurality of recording modes and that can set a plurality of recording head drive frequencies by changing the recording mode is increasing.

JP 2004-230775 A JP 2007-90688 A JP 2006-35568 A

  As a result of intensive studies by the present inventors, the ejection stability is not only deteriorated due to drying and thickening of the ink in the vicinity of the nozzle of the recording head, but also tends to be deteriorated by increasing the driving frequency of the recording head. I understood it.

  However, the techniques disclosed in Patent Documents 1 and 2 can prevent ink thickening in the vicinity of the nozzles of the recording head, but the aftermath of the slight vibration given to the meniscus destroys the meniscus, resulting in improved ejection stability. May have adverse effects. Further, the degree of ink thickening in the vicinity of the nozzles of the recording head varies depending on recording conditions such as ink physical properties, ink ejection frequency, and ambient atmosphere (temperature and humidity), and thus a driving method suitable for each condition is required. Furthermore, when the meniscus is destroyed due to some disturbance, if the vibration operation is always applied to the nozzle in which the nozzle is missing, it is difficult to recover the broken meniscus from the vibration operation.

  The technique disclosed in Patent Document 3 is a technique that gives the ink meniscus a slight vibration that does not cause ink to be ejected to nozzles that are not selectively ejected in synchronization with the application of drive waveforms to the nozzles that are ejected. Patent Document 3 does not mention the drive frequency of the nozzle for recording at the time of recording. That is, Patent Document 3 is not a technique for improving ejection stability that tends to deteriorate as the drive frequency of the recording head increases.

Therefore, an object of the present invention is to propose a recording method that improves ejection stability regardless of the drive frequency of the recording head.
It is another object of the present invention to propose a recording method in which a discharge failure caused by accidental destruction of the meniscus is reduced by reducing the meniscus vibration frequency, thereby recovering the discharge failure.
Furthermore, it aims at providing the inkjet recording device which can implement the recording method.

  The recording method of the present invention for solving the above problems includes a recording head provided with nozzles, and a vibration that forms an ink meniscus at the tip of the nozzle and vibrates the meniscus to such an extent that ink is not ejected from the nozzle. A recording method of an ink jet recording apparatus that performs recording by discharging the ink having the meniscus formed from the nozzles, the setting step for setting the driving frequency of the recording head, and the setting step As the drive frequency of the recording head becomes higher, the vibration frequency of the meniscus is decreased, and at least a changing step of controlling and changing the vibration means is provided.

  Another ink jet recording apparatus of the present invention for solving the above-mentioned problems is a recording head provided with a nozzle and an ink meniscus formed at the tip of the nozzle so that the ink is not discharged from the nozzle. An ink jet recording apparatus that performs recording by ejecting the ink having the meniscus from the nozzles, and sets the driving frequency of the recording head, and the setting means As the drive frequency of the recording head increases, the vibration frequency of the meniscus decreases, and at least vibration frequency changing means for controlling and changing the vibration means is provided.

  According to the present invention, the ejection stability is improved by vibrating the meniscus of the ink in the nozzles provided in the recording head at a frequency corresponding to the driving frequency of the recording head. In addition, by reducing the vibration frequency, it is possible to recover the ejection failure caused by the meniscus being destroyed.

1 is a front view schematically showing a schematic configuration of an ink jet recording apparatus according to a preferred embodiment of the present invention. 1 is a block diagram schematically showing a schematic configuration of an ink jet recording apparatus according to a preferred embodiment of the present invention. It is a flowchart which shows preferable embodiment of the inkjet recording method of this invention. It is the flowchart which added the example of the conditions which change meniscus micro-vibration frequency further to the flowchart shown by FIG.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a front view schematically showing a schematic configuration of an ink jet recording apparatus according to a preferred embodiment of the present invention.
As shown in FIG. 1, the inkjet recording apparatus 1 of the present embodiment arranges a recording medium 50 horizontally and conveys it in the depth direction of the paper surface of FIG. 1, and responds to recording data on the surface of the recording medium 50 by an inkjet method. Record images and text.

  The inkjet recording apparatus 1 includes a transport unit 40 that transports the recording medium 50 and a recording unit 41 that records on the recording medium 50. The recording head 9 includes a recording head 9 that performs reciprocating scanning in a direction orthogonal to the conveyance direction of the recording medium 50, and a cleaning unit 10 that cleans the recording head 9. The inkjet recording apparatus 1 includes a control unit (not shown) that controls the entire apparatus including reception of recording data and control of recording operations.

  The transport unit 40 includes a plurality of pinch rollers 3 that are rotated about a horizontal axis along the paper surface by a motor 5 on the substantially flat platen 2 that extends in the depth direction of the paper surface of FIG. A plurality of grid rollers 4 supported by these pinch rollers 3 so as to be rotatable about a rotation axis parallel to the rotation axis of the pinch roller 3 are arranged in the depth direction of the drawing. These grid rollers 4 are aligned above the platen 2 in a horizontal plane extending in the depth direction in FIG. 1 to form a conveyance path for the recording medium 50.

  The recording unit 41 includes a carriage rail 7 that extends in a direction perpendicular to the conveyance direction of the recording medium 50 above the conveyance unit 40 and the cleaning unit 10, and a recording head that is movable along the carriage rail 7. Unit 8 is provided. In addition, a motor 6 that reciprocates the recording head unit 8 on the carriage rail 7 so as to be capable of position control and speed control is provided. Furthermore, a detachable ink cartridge 17 that supplies recording ink to the recording head unit 8 is provided.

  In the present embodiment, the ink cartridge 17 is provided with a plurality of colors of ink for performing color recording, and can be supplied to the recording head unit 8 for each color via a plurality of ink tubes 16 as pipes. It has become. The ink cartridge 17 is provided with a plurality of ink tanks corresponding to each ink, and each ink is accommodated in a corresponding ink tank.

  The recording head unit 8 is provided with a plurality of recording heads 9 on the lower surface side in accordance with the ink color and recording range, and the ink supplied from the ink tube 16 is distributed to the recording heads 9 that perform recording of the same color. Supplied. Further, the recording head unit 8 is provided with a cooling fan 18 for keeping the temperature of each recording head 9 in an appropriate temperature range.

  Although details of the recording head 9 are not shown, an ink chamber for supplying ink to each nozzle and an ejection mechanism using a piezoelectric element are provided. The recording head 9 is configured to be able to perform an idle driving operation in which the ink is ejected and the ink meniscus of the nozzle is finely oscillated by an ejection mechanism using the piezoelectric element. The ink jet recording apparatus 1 of the present embodiment suppresses ink thickening in the vicinity of the nozzles by vibrating the ink meniscus, thereby avoiding ejection failure. In addition, since the influence of this ink thickening may not be eliminated only by the minute vibration, the ink jet recording apparatus 1 performs preliminary ejection that ejects ink outside the image forming range and ejects thickened ink near the nozzle. It is the structure which can perform. Further, the nozzles can be provided with an appropriate number and arrangement pitch according to the configuration of the ejection mechanism, the recording pixel pitch, and the like. For example, a large number of nozzles such as 256 can be arranged. The recording head 9 of this embodiment uses a piezoelectric element as the recording element, but may be a recording head using a heater as the recording element.

  The ink jet recording apparatus 1 according to the present embodiment is configured to slightly vibrate the ink meniscus by vibrating a piezoelectric element as a recording element as vibration means to the extent that ink is not ejected, but is not limited to such a configuration. In addition to the recording element, a vibration means for finely vibrating the ink meniscus may be provided.

  Position control and speed control of the motor 6 are performed according to control signals from the control unit. During the recording operation, the motor 6 is controlled so that the recording head reciprocates on the recording medium 50 at a predetermined speed. Further, the motor 6 can move the recording head unit 8 to a predetermined cleaning position in the cleaning unit 10 during the cleaning operation.

  In this embodiment, the cleaning unit 10 includes a suction cleaning unit 14A that cleans the recording head 9 by sucking the ink in the recording head 9 from the nozzles to the outside, and the recording head 9 by wiping the recording head surface. It consists of a wipe part 14B to be cleaned. The cleaning unit 10 is arranged on the moving path of the recording head unit 8 on the side of the transport unit 40 and below the recording unit 41 in the order of the wipe unit 14B and the suction cleaning unit 14A from the transport unit 40 side. In the present embodiment, the upper positions of the suction cleaning unit 14A and the wipe unit 14B are predetermined cleaning positions.

  The schematic configuration of the suction cleaning unit 14A includes a cap 11, a cap drive unit (not shown), a suction pump 12, a pump drive unit (not shown), an air release valve (not shown), and an air release valve drive unit (not shown). Become.

  Among these, at least the cap 11 is provided for each recording head 9. However, the cap drive unit, the suction pump 12, the air release valve, and the air release valve drive unit may be configured to be provided for each of the plurality of caps 11 when each operation can be made common for each recording head 9. .

  The cap drive unit moves up and down to selectively switch the position of the cap 11 in the vertical direction, and includes, for example, appropriate mechanical, electromagnetic, and fluid lifting means. Therefore, the cap drive unit moves the cap 11 up and down with respect to the recording head unit 8 which is moved above the carriage rail 7 by the motor 6 and positioned above the suction cleaning unit 14A. The state where the head surface is sealed and the state where the sealing is released can be switched.

  The suction pump 12 is for sucking contents such as air and ink in the suction space and discharging them to the outside of the suction space, and an appropriately configured fluid pump such as a rotary pump can be adopted. A liquid passing means for passing ink from the ink cartridge 17 to the recording head 9 and a suction pump 12 are used here. The suction pump 12 has a suction port connected to the suction pipe and a discharge port connected to the discharge pipe. The other end of the discharge pipe is connected to the waste liquid bottle 15.

The wipe unit 14B may have any configuration as long as it performs a known wiping process. For example, it is possible to employ a configuration in which the recording head surface is wiped by relatively moving a wiping blade containing a wiping liquid on the recording head surface of the recording head 9 moved above the wiping portion 14B.

FIG. 2 is a block diagram schematically showing a schematic configuration of an ink jet recording apparatus according to a preferred embodiment of the present invention.
In FIG. 2, reference numeral 20 denotes a control unit. The control unit 20 includes a CPU 24 that executes processing operations such as calculation, control, determination, and setting, a ROM 25 that stores a control program to be executed by the CPU 24, and a recording data A buffer 26 and a RAM 26 used as a work area for processing by the CPU 24 are provided. The input unit 21 outputs recording data input from a host computer (not shown) to the control unit 20.

  In the inkjet recording apparatus 1 of the present embodiment, the control unit 20 operates the recording head 9 via the recording head drive unit 27. When a plurality of recording heads 9 are mounted, the control unit 20 and the recording head driving unit 27 can drive each recording head 9 individually.

  The recording head drive unit 27 generates ink ejection timing or non-ejection timing for each recording head 9 based on the information input from the control unit 20 and drives the recording head 9. When ink ejection is performed, an ON waveform is generated. When ink ejection is not performed, an OFF waveform is generated and transferred to each recording head 9. In addition to these waveforms, a waveform that slightly vibrates the ink meniscus can be generated based on information input from the control unit 20 to the extent that ink is not ejected.

  The recording head 9 is preferably driven at a frequency of 10 kHz to 30 kHz from the viewpoint of recording speed and ejection stability, and the change range of the meniscus vibration frequency is preferably 50 Hz to 30 kHz.

  During the formation of an image in which the frequency of ink ejection from each recording head 9 is high, the control unit 20 can control the recording head 9 via the recording head driving unit 27 so as to reduce the frequency of meniscus microvibration. Conversely, during the formation of an image with a low ink ejection frequency, the control unit 20 can also control the recording head 9 via the recording head drive unit 27 so as to increase the frequency of meniscus microvibration. With this control method by the control unit 20, when an image with high ink ejection frequency is formed, the influence of ink thickening is small, so the frequency of meniscus micro-vibration is reduced, which is effective in improving ejection stability. Conversely, when an image with a small ink discharge amount is formed, meniscus microvibration is frequently performed, and ink thickening can be suppressed.

  The operation panel 22 includes a switch for performing startup, maintenance, paper feed (recording medium supply), paper discharge (discharge of the recording medium), and other operations of the inkjet recording apparatus 1, and a display screen (for example, a liquid crystal screen). Prepare. The user can execute the above operation by operating the switch while looking at the display screen.

  Further, the user can set the drive frequency of the recording head 1 by setting a plurality of recording modes provided in the inkjet recording apparatus 1 on the operation panel 22. Information to be set is transmitted to the control unit 20. The ink jet recording apparatus 1 of the present embodiment has a high speed mode, a standard mode, and a high image quality mode as recording modes, and drives the recording head 1 at driving frequencies of 20 kHz, 15 kHz, and 10 kHz, respectively. The control unit 20 controls the recording head 9 via the recording head driving unit 27 so as to drive the recording head 9 at a driving frequency corresponding to the recording mode set on the operation panel 22.

  Further, the user can set the ink type installed in the inkjet recording apparatus 1 on the operation panel 22 and transmit the information to the control unit 20. The control unit 20 can drive the recording head 9 via the recording head driving unit 27 by appropriately switching to a preset driving method according to the set ink type.

  For example, for ink types that contain a large amount of non-volatile solvent and have a low volatilization rate, the influence of ink thickening in the vicinity of the nozzle is small, so the frequency of meniscus microvibration is reduced to the extent that no significant thickening appears. The discharge stability can be improved. Conversely, for highly volatile ink types that contain a large amount of volatile solvents and water, the ink thickening near the nozzle is significant. Can be suppressed.

  The temperature / humidity measuring unit 23 measures the environmental conditions of the temperature and humidity where the ink jet recording apparatus is placed, and transmits it to the control unit 20. The control unit 20 can drive the recording head 9 via the recording head driving unit 27 by a driving method suitable for the transmitted environmental conditions.

  For example, under an environmental condition where the ink volatilization rate increases, such as high temperature and low humidity, the influence of ink thickening near the nozzles is large, so the control unit 20 increases the frequency of meniscus microvibration to increase the ink thickening. The influence of can be suppressed. On the other hand, under the environmental conditions where the ink volatilization rate is low, such as low temperature and high humidity, the influence of ink thickening near the nozzle is small, so the control unit 20 reduces the meniscus micro-vibration frequency to stabilize ejection. The recording head 9 can be driven so as to improve the performance.

FIG. 3 is a flowchart showing a preferred embodiment of the control method.
First, in step S <b> 100, the inkjet recording apparatus 1 inputs recording data from an external host computer via the input unit 21.

  In step S110, the control unit 20 determines whether the recording mode set by the user via the operation panel 22 is any one of the high speed mode, the standard mode, and the high image quality mode. In the high speed mode, the standard mode, and the high image quality mode, the recording head 1 is driven at driving frequencies of 20 kHz, 15 kHz, and 10 kHz, respectively. Thereafter, when the control unit 20 determines that the high-speed mode is selected, the process proceeds to step S120, and the control unit 20 decreases the meniscus fine vibration frequency from a predetermined meniscus fine vibration frequency. When the control unit 20 determines that the standard mode is selected, the process proceeds to step S130, and the control unit 20 maintains a predetermined meniscus fine vibration frequency. When the control unit 20 determines that the image quality mode is set, the process proceeds to step S140, and the control unit 20 decreases the meniscus fine vibration frequency from a predetermined meniscus fine vibration frequency.

  Next, after any one of steps S120 to S140, the process proceeds to step S190, where the control unit 20 determines whether the recording data input from the external host computer has ended. If the recording data has ended, the recording operation ends. If the recording data does not end, the process returns to step S110, and the processing from step S110 to step S190 is repeated until the recording data ends.

FIG. 4 is a flowchart showing a preferred embodiment in which the meniscus micro-vibration frequency is further changed in accordance with the recording condition with respect to the embodiment of the recording method shown in FIG.
Since the process of inputting recording data from an external host computer and determining the meniscus microvibration frequency according to the recording mode is the same as the flow from step S100 to step S140 in FIG. 3, detailed description thereof is omitted. .

  In the present embodiment, after any one of steps S120 to S140 in FIG. 3, the process proceeds to step S150 in FIG. 4, and the meniscus fine vibration frequency is set according to the recording conditions. Specific recording conditions are ink type, ink ejection frequency, environmental temperature where the ink jet recording apparatus is installed, and environmental humidity where the ink jet recording apparatus is installed. In the present embodiment, the meniscus microvibration frequency is changed according to the ink ejection frequency among the recording conditions. However, the present invention may use any one of the recording conditions described above. A plurality of recording conditions may be used.

  When changing the meniscus micro-vibration frequency according to the ink ejection frequency, in step S150, the control unit 20 detects the ink ejection frequency of the recording head during recording. If the discharge frequency is higher than a preset upper limit value, the process proceeds to step S160, and the meniscus fine vibration frequency is decreased. On the other hand, if it is lower than the preset lower limit, the process proceeds to step S180 to increase the meniscus fine vibration frequency. If the discharge frequency is within the predetermined lower limit value and upper limit value, the process proceeds to step S170, and the meniscus fine vibration frequency is maintained.

  For example, in the case of changing the meniscus microvibration frequency according to the type of ink, the type of ink loaded in the recording apparatus 1 is input by the operation panel 22. If the ink type is an ink with little influence of thickening, the meniscus fine vibration frequency is decreased in a step corresponding to step S160. On the contrary, if the ink has a large effect of thickening, the meniscus fine vibration speed is increased in a step corresponding to step S180. If the ink is neither of the above, the meniscus fine vibration frequency is maintained in a step corresponding to step S170.

  In the embodiment in which the meniscus micro-vibration frequency is changed according to the temperature environment in which the ink jet recording apparatus is installed and the humidity environment in which the ink jet recording apparatus is installed, the temperature / humidity measuring unit is a step corresponding to step S150. 23 measures the temperature and humidity and transmits them to the control unit 20. If the transmitted environmental condition of temperature and humidity is a preset low temperature and high humidity condition that has a small influence of drying, the control unit 20 decreases the meniscus microvibration frequency in a step corresponding to step S160. If the preset high-temperature / low-humidity conditions have a great influence of drying, the frequency of meniscus slight vibration is increased in a step corresponding to step S180. If the temperature / humidity environment conditions are neither of the above, the meniscus microvibration frequency is maintained in a step corresponding to step S170. Moreover, any one of temperature and humidity may be used as the environmental condition to be detected.

  After changing the meniscus micro-vibration frequency according to the recording conditions, the process proceeds to step S190 in FIG. 3, and the recording is continued until the recording is completed. In the present invention, the ink mounted on the ink jet recording apparatus is a solvent-based ink containing at least a pigment, a binder resin, and a solvent solvent, and is preferably an ink having a water content of 5% or less. This is because solvent ink has less influence of ink thickening in the vicinity of the nozzle than water-based ink having high volatility, and thus the frequency of meniscus fine vibration that can be set is wide and more effective.

  The ink jet recording method and the ink jet recording apparatus of the present invention can be used for a general ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Recording device 8 Recording head unit 9 Recording head 20 Control part 21 Input part 22 Operation panel 23 Temperature / humidity measurement part 27 Recording head drive part

Claims (6)

A recording head provided with a nozzle; and a vibrating means that forms an ink meniscus at the tip of the nozzle and vibrates the meniscus to such an extent that the ink is not ejected from the nozzle. The ink having the meniscus formed from the nozzle A recording method of an ink jet recording apparatus that performs recording by discharging,
A setting step for setting a drive frequency of the recording head;
A recording method comprising at least a changing step of controlling and changing the vibration means so that the vibration frequency of the meniscus decreases as the driving frequency of the recording head set in the setting step increases. The recording method is:
It further has a detection step of detecting a predetermined recording condition,
The changing step includes
The recording method according to claim 1, further comprising changing a vibration frequency of the meniscus based on the recording condition.   The recording condition is at least one of the type of ink, the ejection frequency of the ink, the environmental temperature in which the inkjet recording apparatus is installed, and the environmental humidity in which the inkjet recording apparatus is installed. The recording method according to claim 2.   4. The recording according to claim 1, wherein a driving frequency of the recording head is 10 kHz or more and 30 kHz or less, and a change range of a vibration frequency of the meniscus is 50 Hz or more and 30 kHz or less. Method.   The recording method according to claim 1, wherein the ink includes at least a pigment, a binder resin, and a solvent solvent, and the water content of the ink is 5% or less. A recording head having a nozzle; and a vibrating unit that forms an ink meniscus at the tip of the nozzle and vibrates the meniscus to such an extent that the ink is not ejected from the nozzle. The ink having the meniscus is ejected from the nozzle. An inkjet recording apparatus that performs recording,
Setting means for setting the drive frequency of the recording head;
An ink jet recording apparatus having at least vibration frequency changing means for controlling and changing the vibration means so that the vibration frequency of the meniscus decreases as the drive frequency of the recording head set by the setting means increases.

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