JP2018149764A - Droplet discharge device and moisture retention method for discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet discharge device and a moisture retention method for a discharge head, which are capable of preventing deterioration of discharge performance of the discharge head.SOLUTION: A droplet discharge device which, when it is determined that a relation between a measured temperature of cap liquid and an adjusted first temperature of discharge liquid does not satisfy a first relation between a temperature of discharge liquid and a temperature of cap liquid which causes a humidity in a moisture retention space formed by a moisture retention cap and a nozzle surface to be a humidity that prevents drying of the nozzle and due condensation on the nozzle surface, sets the temperature of discharge liquid to a second temperature which satisfies the first relation while the temperature of cap liquid is at the measured temperature.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a droplet discharge device and a moisture retention method for an ejection head, and more particularly to a droplet ejection device and a moisture retention method for an ejection head in which a nozzle surface of the ejection head is moisturized with a moisture retention cap.

  In the liquid droplet ejection device, when the ink inside the nozzle provided on the nozzle surface of the ejection head is dried, the nozzle is clogged with the dried ink, resulting in ejection failure. For this reason, when the ink is not discharged, the nozzle surface is sealed with a moisture retaining cap in which the cap liquid is stored, and the humidity of the nozzle surface is maintained at a humidity at which the ink inside the nozzle does not dry. Yes.

  In addition, when condensation occurs on the nozzle surface, water droplets generated by the condensation may hit the discharge nozzle and adversely affect image quality. Therefore, it is necessary to maintain the humidity of the nozzle surface at a humidity that prevents condensation while drying.

  Patent Document 1 discloses a cap member (corresponding to a moisturizing cap) for capping the nozzle surface of the ejection head, a moisturizing liquid tank for retaining a moisturizing liquid (corresponding to the cap liquid), and a temperature and humidity sensor provided in the cap member And a temperature control device that changes the temperature of the moisturizing liquid, and determines whether the humidity is equal to or higher than a predetermined threshold based on the detection result of the temperature / humidity sensor. An apparatus for operating the apparatus to heat the moisturizing liquid is described.

  According to the apparatus described in Patent Document 1, it is possible to suppress moisture evaporation from the ink inside the nozzle by capping the nozzle surface, and to adjust the cap liquid temperature according to the temperature and humidity in the cap member. Condensation in the cap member can be prevented.

JP 2008-1000040 A

  However, the device described in Patent Document 1 requires a temperature control device for adjusting the temperature of the cap liquid, and thus has a drawback of being costly and complicated in configuration.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a droplet discharge device and a moisture retention method for the discharge head that prevent the discharge performance of the discharge head from deteriorating without adjusting the temperature of the cap liquid. And

  In order to achieve the above object, one aspect of a droplet discharge device includes: a discharge head that discharges droplets of discharge liquid from a nozzle disposed on a nozzle surface; a discharge liquid tank that stores discharge liquid; and a discharge liquid tank A circulation unit that circulates the discharge liquid between the liquid discharge head and the discharge head, a temperature adjustment unit that adjusts the temperature of the discharge liquid, a control unit that sets the temperature of the discharge liquid adjusted by the temperature adjustment unit to a first temperature, A moisturizing cap that stores the cap liquid and covers the nozzle surface to form a moisturizing space with the nozzle surface, and a discharge liquid for the humidity of the moisturizing space to be a humidity that prevents drying of the nozzle and condensation on the nozzle surface A storage unit that stores a first relationship between the temperature of the liquid and the temperature of the cap liquid, a temperature measurement unit that measures the temperature of the cap liquid, and the measured temperature of the cap liquid and the first temperature of the discharge liquid have a first relationship. A determination unit that determines whether or not , The control unit, when it is determined not to satisfy the first relation by the determination unit, the temperature of the discharged liquid is set at a temperature of the measured capped liquid to a second temperature which satisfies the first relationship.

  According to this aspect, since the discharge liquid is circulated between the discharge liquid tank and the discharge head and the temperature of the discharge liquid is adjusted to the first temperature, the nozzle surface temperature of the discharge head is estimated to be equal to the first temperature. Is done. In this state, the relationship between the measured temperature of the cap liquid and the adjusted first temperature of the discharged liquid indicates that the humidity of the moisturizing space formed by the moisturizing cap and the nozzle surface prevents the nozzle from drying and the nozzle surface from condensing. If it is determined that the first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for achieving a certain humidity is not satisfied, the temperature of the discharge liquid is set to a second temperature that satisfies the first relationship in the measured temperature of the cap liquid. Since it is set, the temperature of the nozzle surface becomes equal to the second temperature, so that drying of the nozzle and dew condensation on the nozzle surface can be prevented, and deterioration of the discharge performance of the discharge head can be prevented.

  When it is determined by the determination unit that the first relationship is satisfied, the control unit preferably sets the temperature of the discharge liquid to the first temperature. Thereby, drying of the nozzle and condensation on the nozzle surface can be prevented, and deterioration of the discharge performance of the discharge head can be prevented.

  It is preferable to include a medium conveying unit that conveys a recording medium and an image recording unit that records an image on a recording medium that is conveyed by ejecting ink that is an ejection liquid from a nozzle. Thereby, ink can be discharged and an image can be appropriately recorded.

  When the image recording unit records an image with the ink temperature set to the second temperature, it is preferable to include a warning unit that issues a warning that there is a concern about the image quality of the image. Thereby, when an image is recorded at the second temperature, the user can know that there is a concern about the image quality of the image.

  The discharge head has a drive element for discharging the discharge liquid from the nozzle. When the temperature of the discharge liquid is set to the first temperature, the drive element is driven with the first drive voltage, and the temperature of the discharge liquid Is set to a temperature lower than the first temperature, the drive element is driven with a second drive voltage higher than the first drive voltage, and the temperature of the discharge liquid is set to a temperature higher than the first temperature. The driving element is preferably driven with a third driving voltage lower than the first driving voltage. Accordingly, the drive element can be driven with a drive voltage suitable for the temperature of the discharge liquid, and thus the discharge liquid can be appropriately discharged from the nozzle.

  A setting unit configured to set a vacation mode in which the state where the nozzle surface is covered with the moisturizing cap is maintained for a period of time equal to or greater than the threshold period, and when the vacation mode is set, the determination unit determines that the temperature of the measured cap liquid It is determined whether or not the first temperature is higher than the temperature of the cap liquid that satisfies the first relationship, and the control unit determines that the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship. If it is determined, it is preferable to stop the operation of the temperature adjustment unit. Thereby, the electric power for operation | movement of a temperature adjustment part can be reduced.

  In order to achieve the above object, one aspect of a droplet discharge device includes: a discharge head that discharges droplets of discharge liquid from a nozzle disposed on a nozzle surface; a discharge liquid tank that stores discharge liquid; and a discharge liquid tank A circulation unit that circulates the discharge liquid between the liquid discharge head and the discharge head, a temperature adjustment unit that adjusts the temperature of the discharge liquid, a control unit that sets the temperature of the discharge liquid adjusted by the temperature adjustment unit to a first temperature, A moisturizing cap that stores the cap liquid and covers the nozzle surface to form a moisturizing space with the nozzle surface, and a discharge liquid for the humidity of the moisturizing space to be a humidity that prevents drying of the nozzle and condensation on the nozzle surface A storage unit that stores a first relationship between the temperature of the liquid and the temperature of the cap liquid, a setting unit that sets the vacation mode in which the state of covering the nozzle surface with the moisture retaining cap is maintained for a period equal to or longer than the threshold period, and the temperature of the cap liquid Temperature measurement And a determination unit that determines whether or not the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship at the first temperature of the discharged liquid, and the control unit measures If it is determined that the temperature of the cap liquid is higher than the temperature of the cap liquid satisfying the first relationship, the temperature of the discharged liquid is the first temperature at the measured cap liquid temperature when the vacation mode is not set. The second temperature that satisfies the relationship is set to a second temperature that is higher than the first temperature. When the vacation mode is set, the operation of the temperature adjustment unit is stopped.

  According to this aspect, since the discharge liquid is circulated between the discharge liquid tank and the discharge head and the temperature of the discharge liquid is adjusted to the first temperature, the nozzle surface temperature of the discharge head is estimated to be equal to the first temperature. Is done. In this state, the relationship between the measured temperature of the cap liquid and the adjusted first temperature of the discharged liquid indicates that the humidity of the moisturizing space formed by the moisturizing cap and the nozzle surface prevents the nozzle from drying and the nozzle surface from condensing. If it is determined that the first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for achieving a high humidity is not satisfied, the temperature of the discharge liquid is measured when the temperature of the discharge liquid is not set in the vacation mode. Since the temperature is not adjusted when the vacation mode is set to the second temperature that satisfies the first relationship, the nozzle surface temperature is equal to the second temperature when the vacation mode is not set. Therefore, condensation on the nozzle surface can be prevented, and when the vacation mode is set, condensation on the nozzle surface is allowed to save power.

  A discharge liquid temperature measurement unit that measures the temperature of the discharge liquid is provided, and the determination unit has a first relationship between the measured temperature of the cap liquid and the measured temperature of the discharge liquid when the operation of the temperature adjustment unit is stopped. It is preferable to determine whether or not the temperature is higher than the temperature of the cap liquid that satisfies the condition. Thereby, even when the operation of the temperature adjustment unit is stopped, it is possible to appropriately determine whether or not the humidity of the moisturizing space is a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented. .

  It is preferable that a temperature measurement part is arrange | positioned on the outer side of a moisture retention cap. Thereby, it is not necessary to apply a waterproof process to the temperature measuring unit, and the cost can be reduced.

  The circulation unit includes a supply flow path that connects the discharge liquid tank and the discharge head, a supply pump that supplies the discharge liquid stored in the discharge liquid tank to the discharge head via the supply flow path, and the discharge head and the discharge liquid. It is preferable to include a recovery channel that communicates with the tank, and a recovery pump that recovers the discharge liquid inside the discharge head to the discharge head via the recovery channel. Thereby, it is possible to prevent the ink inside the head from sticking.

  The temperature adjustment unit is preferably provided in the supply flow path. Thereby, the temperature of the discharged liquid can be adjusted appropriately.

  The discharge head preferably includes a nozzle supply channel that communicates the supply channel and the nozzle, and a nozzle recovery channel that communicates the recovery channel and the nozzle. Thereby, the viscosity increase of the ink inside the nozzle can be prevented, and the temperature of the nozzle surface can be set to the temperature of the discharge liquid.

  The first relationship is a relationship that defines the temperature range of the cap liquid so that the humidity of the moisturizing space becomes the humidity at which the drying of the nozzle and the condensation on the nozzle surface are prevented for each temperature of the discharged liquid. Is higher, the upper limit temperature and the lower limit temperature of the cap liquid temperature range are higher, and the determination unit determines whether the measured temperature of the cap liquid is within the range with respect to the first temperature of the discharge liquid. It is preferable to determine whether or not. Thereby, it can be determined appropriately whether the measured temperature of the cap liquid and the first temperature of the discharged liquid satisfy the first relationship.

  In order to achieve the above object, one aspect of the moisturizing method of the discharge head is to discharge between a discharge head that discharges droplets of discharge liquid from a nozzle arranged on the nozzle surface and a discharge liquid tank that stores the discharge liquid. A circulation step for circulating the liquid, a temperature adjustment step for adjusting the temperature of the discharge liquid, a control step for setting the temperature of the discharge liquid adjusted by the temperature adjustment step to the first temperature, and a moisturizing cap that stores the cap liquid A moisturizing space forming step of covering the nozzle surface and forming a moisturizing space between the moisturizing cap and the nozzle surface, and a discharge liquid for reducing the humidity of the moisturizing space to prevent the nozzle from drying and dew condensation on the nozzle surface The storage step of storing the first relationship between the temperature and the temperature of the cap liquid in the storage unit, the temperature measurement step of measuring the temperature of the cap liquid, and the measured temperature of the cap liquid and the first temperature of the discharge liquid are the first. Meet relationship A determination step for determining whether or not the control step satisfies the first relationship in the measured cap liquid temperature when the determination step determines that the first relationship is not satisfied. Set to the second temperature.

  According to this aspect, since the discharge liquid is circulated between the discharge liquid tank and the discharge head and the temperature of the discharge liquid is adjusted to the first temperature, the nozzle surface temperature of the discharge head is estimated to be equal to the first temperature. Is done. In this state, the relationship between the measured temperature of the cap liquid and the adjusted first temperature of the discharged liquid indicates that the humidity of the moisturizing space formed by the moisturizing cap and the nozzle surface prevents the nozzle from drying and the nozzle surface from condensing. If it is determined that the first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for achieving a certain humidity is not satisfied, the temperature of the discharge liquid is set to a second temperature that satisfies the first relationship in the measured temperature of the cap liquid. Since it is set, the temperature of the nozzle surface becomes equal to the second temperature, so that drying of the nozzle and dew condensation on the nozzle surface can be prevented, and deterioration of the discharge performance of the discharge head can be prevented.

  In order to achieve the above object, one aspect of the moisturizing method of the discharge head is to discharge between a discharge head that discharges droplets of discharge liquid from a nozzle arranged on the nozzle surface and a discharge liquid tank that stores the discharge liquid. A circulation step for circulating the liquid, a temperature adjustment step for adjusting the temperature of the discharge liquid, a control step for setting the temperature of the discharge liquid adjusted by the temperature adjustment step to the first temperature, and a moisturizing cap that stores the cap liquid A moisturizing space forming step of covering the nozzle surface and forming a moisturizing space between the moisturizing cap and the nozzle surface, and a discharge liquid for reducing the humidity of the moisturizing space to prevent the nozzle from drying and dew condensation on the nozzle surface A storage step of storing the first relationship between the temperature and the temperature of the cap liquid in the storage unit; a setting step of setting a vacation mode in which the state where the nozzle surface is covered by the moisturizing cap is maintained for a period longer than the threshold period; A temperature measurement step for measuring the temperature of the cap liquid, and a determination step for determining whether the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship at the first temperature of the discharge liquid; And the control step determines that the measured temperature of the cap liquid is higher than the temperature of the cap liquid satisfying the first relationship, and sets the temperature of the discharged liquid when the vacation mode is not set, If the measured temperature of the cap liquid is a second temperature that satisfies the first relationship and is higher than the first temperature, and the vacation mode is set, the temperature adjustment process is stopped.

  According to this aspect, since the discharge liquid is circulated between the discharge liquid tank and the discharge head and the temperature of the discharge liquid is adjusted to the first temperature, the nozzle surface temperature of the discharge head is estimated to be equal to the first temperature. Is done. In this state, the relationship between the measured temperature of the cap liquid and the adjusted first temperature of the discharged liquid indicates that the humidity of the moisturizing space formed by the moisturizing cap and the nozzle surface prevents the nozzle from drying and the nozzle surface from condensing. If it is determined that the first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for achieving a high humidity is not satisfied, the temperature of the discharge liquid is measured when the temperature of the discharge liquid is not set in the vacation mode. Since the second temperature satisfying the first relationship is set and the temperature adjustment is stopped when the vacation mode is set, the temperature of the nozzle surface is equal to the second temperature when the vacation mode is not set. Therefore, condensation on the nozzle surface can be prevented, and when the vacation mode is set, condensation on the nozzle surface is allowed to save power.

  According to the present invention, it is possible to prevent the discharge performance of the discharge head from being deteriorated.

Front view showing the configuration of the main part of the inkjet recording apparatus A plan view showing a configuration of a main part of an ink jet recording apparatus Side view showing the configuration of the main part of the inkjet recording apparatus Plane perspective view showing structural example of head 5-5 sectional view of FIG. Schematic diagram of ink circulation unit Schematic showing the positional relationship between the head and the moisture retention cap at the maintenance position Block diagram showing schematic configuration of control system of inkjet recording apparatus Flow chart showing a head moisturizing method according to the present embodiment. A graph showing the relationship between the cap liquid temperature and the humidity of the moisturizing space Diagram showing drive waveforms applied to individual electrodes Flowchart illustrating a method for setting image recording conditions when a print job of an inkjet recording apparatus is started Block diagram showing schematic configuration of control system of inkjet recording apparatus Flow chart showing the method of moisturizing the head Graph showing proper relationship between ink temperature and cap liquid temperature threshold

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
[Configuration of inkjet recording apparatus]
1 to 3 are a front view, a plan view, and a side view, respectively, showing a configuration of a main part of the ink jet recording apparatus according to the present embodiment.

  The inkjet recording apparatus 10 (an example of a droplet discharge apparatus) is a single-pass line printer, and mainly includes a sheet conveyance unit 20 that conveys a sheet 1 that is a recording medium, and heads 32C and 32M that are a plurality of inkjet heads. , 32Y, and 32K, the head moving mechanism 35 (see FIG. 8) that moves the heads 32C, 32M, 32Y, and 32K, and the heads 32C, 32M, 32Y, and 32K are maintained. The maintenance unit 80 includes a head cleaning unit 90 that cleans the heads 32C, 32M, 32Y, and 32K.

(Paper transport section)
The paper transport unit 20 (an example of a medium transport unit) transports the paper 1 by attracting the paper 1 to the traveling belt 22. The travel route is set so that the belt 22 travels horizontally at some points. The paper transport unit 20 transports the paper 1 horizontally using a place where the belt 22 travels horizontally as a transport path. The paper 1 is transported along the transport path by the paper transport unit 20.

(Image recording part)
The image recording unit 30 includes heads 32C, 32M, 32Y, and 32K, and an ink circulation unit 52 that circulates and supplies ink to the heads 32C, 32M, 32Y, and 32K (see FIG. 6). The

  Each of the heads 32 </ b> C, 32 </ b> M, 32 </ b> Y, and 32 </ b> K is configured by a line head corresponding to the maximum paper width of the paper 1 to be printed, and is attached to the head support frame 31. Each of the heads 32C, 32M, 32Y, and 32K ejects cyan ink droplets (an example of a droplet), magenta ink droplets, yellow ink droplets, and black ink droplets, and is transported by the paper transport unit 20. An image is recorded on the recording surface of the paper 1.

  Since the configurations of the heads 32C, 32M, 32Y, and 32K are the same, the following description will be made with the head 32 unless otherwise specified.

(head)
4 is a plan perspective view showing a structural example of the head 32, and FIG. 5 is a sectional view taken along the line 5-5 in FIG.

  The head 32 includes a plurality of nozzles 34 serving as ink droplet ejection holes on a nozzle surface 33 serving as a bottom surface of the head 32. In addition, a plurality of ink chamber units 38 including pressure chambers 36 and the like provided corresponding to the nozzles 34 are two-dimensionally arranged in a fixed arrangement pattern. This achieves a substantial increase in the spacing between the nozzles that are projected along the X direction.

  The pressure chamber 36 has a substantially square planar shape, and nozzles 34 and ink inlets 39 are provided at both diagonal corners. Each pressure chamber 36 is connected to an individual flow path 40 (an example of a nozzle supply flow path) via an ink inlet 39, and each individual flow path 40 is connected to a common flow path 41. Further, the nozzle flow path 42 communicating with each pressure chamber 36 is communicated with the circulation common flow path 44 via an individual circulation flow path 43 (an example of a nozzle recovery flow path). The head 32 is provided with a supply port 46 and a discharge port 47, the supply port 46 communicates with the common flow channel 41, and the discharge port 47 communicates with the circulation common flow channel 44.

  As described above, the supply port 46 and the discharge port 47 of the head 32 include the common channel 41, the individual channel 40, the ink inlet 39, the pressure chamber 36, the nozzle channel 42, the individual circulation channel 43, and the circulation common flow. It is configured to communicate with each other via a path 44.

  Therefore, the ink supplied to the supply port 46 flows through the common channel 41, the individual channel 40, and the nozzle channel 42, a part is ejected from each nozzle 34, and the remaining ink is circulated through the individual circulation channel 43 and the circulation. It is discharged from the discharge port 47 via the common flow path 44.

  The individual circulation channel 43 is preferably connected to the vicinity of the nozzle 34 of the nozzle channel 42. As a result, the ink circulates in the vicinity of the nozzle 34, so that thickening of the ink inside the nozzle 34 is prevented and stable ejection becomes possible.

  In addition, a piezoelectric element 50 (an example of a driving element) including individual electrodes 49 is joined to a diaphragm 48 that constitutes the top surface of the pressure chamber 36 and also serves as a common electrode. When a voltage is applied to the individual electrode 49, the piezoelectric element 50 is deformed in a direction in which the pressure chamber 36 is contracted. Thereby, ink is ejected from the nozzle 34. Thereafter, the piezoelectric element 50 is deformed in a direction in which the pressure chamber 36 is expanded. As a result, new ink is supplied from the common channel 41 to the pressure chamber 36 through the individual channel 40 and the ink inlet 39.

  Here, the piezoelectric element 50 is applied as a means for generating the ejection force of the ink ejected from the nozzle 34. However, a thermal method is provided in which a heater is provided in the pressure chamber 36 and ink is ejected using the pressure of film boiling caused by heating of the heater. It is also possible to apply.

  The arrangement structure of the nozzles 34 is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the X direction can be applied.

(Ink circulation part)
FIG. 6 is a schematic diagram of the ink circulation unit 52. The ink circulation unit 52 includes a circulation tank 54, a supply channel 56, a temperature adjustment unit 58, a supply pump 60, a recovery channel 62, a recovery pump 64, a replenishment tank 66, a replenishment channel 68, and a replenishment pump 70. .

  In the circulation tank 54 (an example of a discharge liquid tank), ink of a color used in the head 32 (an example of a discharge liquid) is stored. In this embodiment, water-based ink is used. The water-based ink is an ink whose main component is water, for example, an ink whose water is 50% by mass or more of the solvent. It may contain a water-soluble organic solvent or the like.

  The supply channel 56 communicates the circulation tank 54 and the supply port 46 of the head 32.

  The temperature adjustment unit 58 is a heating / cooling device for adjusting the temperature of the ink stored in the circulation tank 54 (ink temperature), and for example, a Peltier element is used. The ink temperature is maintained at a constant temperature by the temperature adjustment unit 58.

  The supply pump 60 is a liquid supply means provided in the supply flow path 56 and supplies the ink stored in the circulation tank 54 to the head 32.

  Further, the recovery flow path 62 communicates the discharge port 47 of the head 32 and the circulation tank 54. The recovery pump 64 is a liquid supply means provided in the recovery flow path 62 and supplies the ink inside the head 32 to the circulation tank 54.

  The replenishment tank 66 stores ink of the same color as the ink stored in the circulation tank 54. The replenishment channel 68 communicates the replenishment tank 66 and the circulation tank 54. The replenishment pump 70 is a liquid feeding means provided in the replenishment flow path 68, and feeds the ink stored in the replenishment tank 66 to the circulation tank 54.

  In the ink circulation unit 52 configured as described above, the temperature of the ink stored in the circulation tank 54 is adjusted by the temperature adjustment unit 58. Further, the ink stored in the circulation tank 54 is fed to the head 32 by the supply pump 60, and the ink that has been fed to the head 32 by the recovery pump 64 is not ejected from the nozzle 34 (see FIG. 5). Ink is fed to the circulation tank 54.

  Further, the amount of ink reduced from the inside of the circulation tank 54 due to the ejection of ink from the nozzles 34 is sent from the replenishment tank 66 to the circulation tank 54 by the replenishment pump 70.

  In this way, since the ink circulates inside the head 32, the ink inside the head 32 is always kept in a fresh state, so that the ink inside the head 32 can be prevented from sticking.

  Further, since the ink whose temperature is kept constant by the temperature adjusting unit 58 is supplied to the head 32 and circulates inside the head 32, the discharge state of the head 32 can be kept constant and the temperature of the nozzle surface 33 can be maintained. Is maintained at the same temperature as the ink temperature due to conduction of the ink temperature.

  In addition, the temperature adjustment part 58 is not limited to the aspect arrange | positioned in the circulation tank 54, You may arrange | position to the supply flow path 56 or the collection | recovery flow path 62, and may be arrange | positioned in several positions.

(Head moving mechanism)
Returning to the description of FIGS. 1 to 3, the head support frame 31 includes a head mounting portion (not shown) for mounting the heads 32C, 32M, 32Y, and 32K. Each head 32 is detachably attached to the head attachment portion.

  When each head 32 is attached to the head support frame 31, the nozzle surface 33 (see FIG. 5) is arranged in parallel with the XY plane which is a horizontal plane, and each head 32 is orthogonal to the Y direction which is the conveyance direction of the paper 1. They are arranged with a constant interval along the Y direction.

  The head mounting portion is provided so that the position in the Z direction, which is the vertical direction, can be adjusted. Each head 32 attached to the head attachment portion adjusts the distance between the nozzle surface 33 and the paper 1 by adjusting the position of the head attachment portion in the Z direction.

  The head moving mechanism 35 (see FIG. 8) horizontally moves the head support frame 31 in the X direction orthogonal to the Y direction. The head moving mechanism 35 includes, for example, a ceiling frame installed horizontally across the paper transport unit 20, a guide rail laid on the ceiling frame, a traveling body that slides on the guide rail, and the traveling body. And drive means for moving along the guide rail. As the driving means, for example, a feed screw mechanism including a feed screw and a motor that rotationally drives the feed screw can be used. The head support frame 31 is attached to the traveling body and slides horizontally.

  Each head 32 attached to the head support frame 31 moves between a predetermined “image recording position” and “maintenance position” when the head support frame 31 is driven by the head moving mechanism 35 and moved horizontally. .

  At the image recording position, each head 32 faces the paper transport unit 20. The paper 1 is transported along the transport path by the paper transport unit 20. When the paper 1 passes through the lower direction of each head 32 in the Z direction, ink droplets are ejected from each head 32 toward the paper 1. As a result, an image is recorded on the paper 1.

  On the other hand, at the maintenance position, each head 32 faces the maintenance unit 80.

(Maintenance Department)
The maintenance unit 80 includes moisturizing caps 82C, 82M, 82Y, and 82K that cover the nozzle surfaces 33 (see FIG. 5) of the heads 32C, 32M, 32Y, and 32K, respectively. In addition, since the structure of each of the moisturizing caps 82C, 82M, 82Y, and 82K is the same, the following description will be made as the moisturizing cap 82 unless otherwise distinguished.

  The moisturizing cap 82 stores a cap liquid for moisturizing the nozzle surface 33.

  The cap liquid is a liquid containing water as a main component, and preferably a liquid containing about 0.5% to 1.5% of a surfactant. Here, “C-FJ-CM” (product name) manufactured by FUJIFILM Corporation is used.

  FIG. 7 is a schematic diagram showing the positional relationship between the head 32 and the moisture retaining cap 82 at the maintenance position. As shown in the figure, in the maintenance position, the head 32 is positioned in the upper direction of the moisturizing cap 82 in the Z direction, and the moisturizing cap 82 covers the nozzle surface 33 of the head 32 and forms the moisturizing space SP with the nozzle surface 33. Form. In the moisturizing space SP, the nozzle surface 33 is moisturized by evaporation of moisture in the cap liquid. Thereby, non-ejection of ink due to drying of the inside of the nozzle 34 (see FIG. 5) is prevented.

  Further, a temperature sensor 83 is provided at a position to be immersed in the cap liquid inside the moisturizing cap 82. The temperature sensor 83 is temperature measuring means for measuring the temperature of the cap liquid (cap liquid temperature) stored in the moisturizing cap 82, and is waterproofed.

  The cap liquid temperature is a temperature corresponding to the ambient temperature of the inkjet recording apparatus 10. Accordingly, the temperature sensor 83 may be provided at a position where the temperature sensor 83 is not immersed in the cap liquid inside the moisturizing cap 82 or at a position outside the moisturizing cap 82 to measure the ambient temperature of the inkjet recording apparatus 10. As a result, waterproofing of the temperature sensor 83 is not necessary, and costs can be reduced. In addition, when providing in the position outside the moisture retention cap 82, providing in the position which contacts the moisture retention cap 82 is preferable.

  The moisturizing cap 82 is provided with a pressure mechanism (not shown) for pressurizing the inside of the nozzle 34 and a suction mechanism (not shown) for sucking the inside of the nozzle. The inside of the nozzle 34 can be pressurized and sucked.

  Further, as shown in FIG. 1, a waste liquid tray 84 is disposed at a lower position in the Z direction of the moisturizing cap 82. The cap liquid supplied to the moisturizing cap 82 is discarded to the waste liquid tray 84 and is recovered from the waste liquid tray 84 to the waste liquid tank 88 through the waste liquid recovery pipe 86.

(Head cleaning part)
The head cleaning unit 90 is installed between the image recording position on the movement path of the head 32 and the maintenance position.

  The head cleaning unit 90 includes nozzle surface wiping devices 94C, 94M, 94Y, and 94K that individually wipe the nozzle surfaces 33 of the heads 32C, 32M, 32Y, and 32K. The nozzle surface wiping devices 94C, 94M, 94Y, and 94K are installed on a common base 92 in accordance with the installation intervals of the heads 32C, 32M, 32Y, and 32K.

  Each nozzle surface wiping device 94C, 94M, 94Y, and 94K presses the traveling wiping web against the nozzle surface 33 of each head 32C, 32M, 32Y, and 32K that moves between the image recording position and the maintenance position. The nozzle surface 33 is wiped off. Thereby, the dirt adhering to the nozzle surface 33 can be removed.

  In addition, since the structure of each nozzle surface wiping apparatus 94C, 94M, 94Y, and 94K is the same, below, it demonstrates as the nozzle surface wiping apparatus 94 except the case where it distinguishes especially.

[Control system configuration]
FIG. 8 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 10. As shown in the figure, the inkjet recording apparatus 10 includes a system controller 100, a communication unit 102, an image memory 110, a conveyance control unit 112, a head movement control unit 114, an image recording control unit 116, a circulation control unit 118, and an ink temperature control. Unit 120, temperature measurement unit 122, storage unit 124, determination unit 126, operation unit 128, display unit 130, and nonvolatile memory 132.

The system controller 100 includes a CPU (Central Processing Unit) 104, a ROM
(Read Only Memory) 106 and RAM (Random Access Memory) 108 are provided. The ROM 106 stores various programs and control data. The RAM 108 temporarily stores programs and data executed by the CPU 104.

  The system controller 100 executes a program read from the ROM 106 in the CPU 104, thereby functioning as a control unit that performs overall control of each unit of the inkjet recording apparatus 10, and also functions as a calculation unit that performs various calculation processes.

  The communication unit 102 includes a communication interface, and transmits / receives data to / from an external host computer 2 connected to the communication interface.

  The image memory 110 functions as a temporary storage unit for various data including image data, and data is read and written through the system controller 100. Image data captured from the host computer 2 via the communication unit 102 is stored in the image memory 110.

  The transport control unit 112 controls the paper transport unit 20 in accordance with a command from the system controller 100, and transports the paper 1 (see FIG. 2) by the paper transport unit 20.

  The head movement control unit 114 controls the head movement mechanism 35 according to a command from the system controller 100, and moves each head 32 between the image recording position and the maintenance position.

  The image recording control unit 116 controls each head 32 in accordance with a command from the system controller 100 and causes each head 32 to record an image on the paper 1.

  The circulation control unit 118 controls the supply pump 60 and the recovery pump 64 in accordance with a command from the system controller 100 and circulates ink inside the head 32.

  The ink temperature control unit 120 (an example of a control unit) controls the temperature adjustment unit 58 in accordance with a command from the system controller 100 to adjust the ink temperature inside the circulation tank 54 (see FIG. 6).

  The temperature measurement unit 122 causes the temperature sensor 83 to measure the cap liquid temperature in response to a command from the system controller 100 and acquires the measurement result from the temperature sensor 83.

  The memory | storage part 124 memorize | stores the relationship between the cap liquid temperature mentioned later and the humidity of the moisture retention space SP.

  The determination unit 126 determines whether or not the cap liquid temperature is within a desired temperature range in accordance with a command from the system controller 100.

  The operation unit 128 includes operation members such as operation buttons, a keyboard, and a touch panel, and outputs operation information input from the operation members to the system controller 100. The system controller 100 executes various processes in accordance with operation information input from the operation unit 128.

  The display unit 130 includes a display device such as an LCD (Liquid Crystal Display) panel, and displays necessary information on the display device in response to a command from the system controller 100.

  The nonvolatile memory 132 is configured by an EEPROM (electrically erasable programmable read only memory) or the like, and records various data and various setting information necessary for control.

  In the ink jet recording apparatus 10 configured as described above, image data to be recorded on the paper 1 is taken into the ink jet recording apparatus 10 from the host computer 2 via the communication unit 102. The captured image data is stored in the image memory 110.

  The system controller 100 generates dot data by performing required signal processing on the image data stored in the image memory 110. Further, the system controller 100 controls the driving of the head 32 by the image recording control unit 116 according to the generated dot data, and records the image represented by the image data on the paper 1.

  The dot data is generally generated by performing color conversion processing and halftone processing on image data. The color conversion process is a process of converting image data expressed in sRGB (standard Red Green Blue) or the like into ink amount data of each color of ink used in the inkjet recording apparatus 10. The halftone process is a process of converting the ink amount data of each color generated by the color conversion process into dot data of each color by a process such as error diffusion.

  The system controller 100 performs color conversion processing and halftone processing on image data to generate dot data for each color. In the present embodiment, single-color dot data is generated. Then, by controlling the driving of each head 32 according to the generated dot data for each color, the image represented by the image data is recorded on the paper 1.

[Moisturizing control]
FIG. 9 is a flowchart showing a moisturizing method for the head 32 (an example of a moisturizing method for the ejection head) according to the present embodiment. The inkjet recording apparatus 10 performs the processing of this flowchart at regular intervals in a state where the head 32 is disposed at the maintenance position and the nozzle surface 33 is covered with the moisture retention cap 82 (an example of a moisture retention space forming step). .

  Here, the ink temperature is maintained at 30 ° C., which is the first temperature, by the temperature adjustment unit 58 (an example of a temperature adjustment step), and the ink circulation inside the head 32 by the ink circulation unit 52 (in the circulation step). As an example, it is assumed that the temperature of the nozzle surface 33 is maintained at 30 ° C., which is the ink temperature.

  First, the temperature measurement unit 122 causes the temperature sensor 83 to measure the cap liquid temperature, and obtains a measurement result from the temperature sensor 83 (step S1, an example of a temperature measurement process).

  Next, the determination unit 126 determines whether or not the cap liquid temperature acquired in step S1 is within a desired temperature range (step S2, an example of a determination step).

  FIG. 10 is a graph showing the relationship between the cap liquid temperature and the humidity inside the moisture retention cap 82, that is, the humidity of the moisture retention space SP. In the figure, the horizontal axis indicates the cap liquid temperature (unit: ° C.), and the vertical axis indicates the humidity (unit: RH% (Relative Humidity%)) of the moisturizing space SP. The graph approximates this relationship for each ink temperature with plot points obtained by experiments for the relationship between the cap liquid temperature and the humidity of the moisturizing space SP when the ink temperatures are 30 ° C., 27 ° C., and 35 ° C., respectively. An approximate straight line is shown. Also, the formula in the figure is an approximate expression representing an approximate straight line.

  The measuring instrument used for the experiment is a thermistor sensor (flange pipe sensor) manufactured by SEMITEC Co., Ltd. for temperature measurement, and a high-glow Klon temperature / humidity logger manufactured by KN Laboratories Co., Ltd.

  Note that the relationship between the cap liquid temperature and the humidity of the moisturizing space SP shown in FIG. 10 depends on the sealing degree of the moisturizing space SP and the surface area of the moisturizing liquid.

  In the ink used in this embodiment, the humidity of the moisturizing space SP needs to be 37 RH% or more so that the ink inside the nozzle 34 does not dry. Further, in order to prevent the nozzle surface 33 from condensing, the humidity of the moisturizing space SP needs to be 65 RH% or less.

  Here, when the ink temperature is 30 ° C., the humidity of the moisturizing space SP is within the range of 37 RH% to 65 RH%. From the approximate straight line shown in FIG. It can be seen that the temperature is in the range of 24.5 ° C.

  As described above, the maintenance unit 80 has an appropriate relationship between the ink temperature and the cap liquid temperature so that the humidity of the moisturizing space SP becomes an appropriate humidity at which the drying of the ink inside the nozzle 34 and the dew condensation on the nozzle surface 33 are prevented. (An example of a first relationship), and this appropriate relationship is stored in the storage unit 124 (an example of a storage step).

  In the present embodiment, the appropriate relationship is a relationship that defines the range of the cap liquid temperature for the humidity of the moisture retaining space SP to be a humidity at which the inside of the nozzle 34 and the condensation on the nozzle surface 33 are prevented for each ink temperature. Yes, the higher the ink temperature, the higher the upper limit temperature and the lower limit temperature of the cap liquid temperature range.

  The storage unit 124 stores, as a table, a range of cap liquid temperature that allows the humidity of the moisturizing space SP to be appropriate for each ink temperature. The storage unit 124 may store the relationship of the graph shown in FIG. 10 or may store an approximate expression for each ink temperature.

  Therefore, in step S2, the determination unit 126 “18.5 ° C. to 24.5 ° C.”, which is the range of the cap liquid temperature for the humidity of the moisturizing space SP to be an appropriate humidity when the ink temperature is 30 ° C. Is read from the storage unit 124 as an appropriate relationship, and whether the cap liquid temperature acquired in step S1 satisfies the read appropriate relationship, that is, whether the cap liquid temperature is within a range of 18.5 ° C. to 24.5 ° C. Determine whether.

  When the cap liquid temperature acquired in step S1 is within the range of 18.5 ° C. to 24.5 ° C., the ink temperature control unit 120 sets the ink temperature by the temperature adjustment unit 58 to 30 ° C. which is the first temperature. It sets (step S3, an example of a control process), and the process of this flowchart is complete | finished.

  As a result, the ink temperature is 30 ° C. and the cap liquid temperature is 18.5 ° C. to 24.5 ° C., so that the appropriate relationship is satisfied, and the humidity of the moisturizing space SP is in the range of 37 RH% to 65 RH. . Therefore, it is possible to prevent the ink inside the nozzle 34 from being dried and the nozzle surface 33 from being condensed.

  On the other hand, when the cap liquid temperature is not within the range of 18.5 ° C. to 24.5 ° C., the ink temperature control unit 120 sets the ink temperature by the temperature adjustment unit 58 to a second temperature different from the first temperature. (Step S4, an example of a control process).

  For example, if the cap liquid temperature is 26 ° C., it can be seen that when the ink temperature is 30 ° C., the humidity of the moisturizing space SP is about 72 RH% from the approximate line shown in FIG. Thus, when the ink temperature is 30 ° C. and the cap liquid temperature is 26 ° C., the proper relationship is not satisfied, and the humidity of the moisture retaining space SP is outside the range of 37 RH% to 65 RH. Therefore, it is necessary to change the ink temperature to satisfy the appropriate relationship.

  Here, the ink temperature control unit 120 sets the ink temperature by the temperature adjustment unit 58 to 35 ° C. that satisfies an appropriate relationship when the cap liquid temperature is 26 ° C. When the ink temperature is 35 ° C. and the cap liquid temperature is 26 ° C., the appropriate relationship is satisfied, and it can be seen that the humidity of the moisturizing space SP is about 58 RH% from the approximate line shown in FIG. As described above, the humidity of the moisturizing space SP can be set within the range of 37 RH% to 65 RH by changing the measured cap liquid temperature to an ink temperature that satisfies an appropriate relationship.

  Subsequently, it is determined whether or not a print job has been started (step S5). If the print job has not been started, the processing of this flowchart ends.

  On the other hand, when the print job is started, the system controller 100 displays a warning that there is a concern about the image quality on the display unit 130 (an example of a warning unit) (an example of issuing a warning; step S6). The process ends.

  In the present embodiment, the first drive voltage is applied to the individual electrode 49 of the head 32 to drive the piezoelectric element 50 and eject ink from the nozzle 34.

FIG. 11 is a diagram showing drive waveforms applied to the individual electrodes 49. In the present embodiment, the driving voltage means a voltage amplitude, and the voltage amplitude is a difference between the highest potential and the lowest potential in the driving waveform. Figure 11 shows a V ₁ is a first driving voltage.

  This first drive voltage is an optimum voltage for ejecting 30 ° C. ink droplets from the nozzle 34 at an appropriate ejection speed and ejection amount. For this reason, when the ink temperature is different from 30 ° C., the ink viscosity and the like are different, so that the image quality of the recorded image may be lowered. Therefore, when the ink temperature is set to a temperature different from 30 ° C., a warning is displayed.

  As described above, according to the present embodiment, even when the cap liquid temperature changes, the humidity of the moisturizing space SP becomes a humidity at which drying of the ink inside the nozzle 34 and condensation on the nozzle surface 33 are prevented. Therefore, it is possible to prevent the ink inside the nozzle 34 from drying and the nozzle surface 33 to condense, and to prevent the discharge performance of the discharge head from deteriorating.

  When the ink temperature is changed, a warning that there is a concern about the image quality is displayed, so that the user can know the fact.

<Second Embodiment>
FIG. 12 is a flowchart illustrating a method for setting image recording conditions when a print job of the inkjet recording apparatus 10 according to the second embodiment is started.

  When the print job is started in a state where the head 32 is moisturized at the maintenance position, the determination unit 126 determines whether or not the ink temperature is set to 30 ° C. which is the first temperature (step S11). .

  If the ink temperature is set to 30 ° C., the drive voltage of the piezoelectric element 50 is set to the first drive voltage (step S12), the process of this flowchart is terminated, and image recording is performed. Similar to the first embodiment, the first drive voltage is an optimum voltage for ejecting 30 ° C. ink droplets from the nozzle 34 at an appropriate ejection speed and ejection amount.

  If the ink temperature is not set to 30 ° C., it is determined whether or not the ink temperature is set to a temperature lower than the first temperature (step S13).

  If the ink temperature is set to a temperature lower than the first temperature, the drive voltage of the piezoelectric element 50 is set to a second drive voltage higher than the first drive voltage (step S14), and the process of this flowchart is terminated. To record an image. When the ink temperature is lower than 30 ° C., the viscosity of the ink is increased, so that driving with the first driving voltage may cause the discharge speed to decrease or the discharge amount to decrease, thereby degrading the image quality. Therefore, by driving with the second drive voltage higher than the first drive voltage, the discharge speed and the discharge amount are adjusted, and the influence on the image quality due to the change of the ink temperature is reduced. As an example, when the ink temperature is set to 27 ° C., it is necessary to set the second drive voltage to a voltage obtained by multiplying the first drive voltage by 1.024 times.

  On the other hand, when the ink temperature is set to a temperature higher than the first temperature, the drive voltage of the piezoelectric element 50 is set to a third drive voltage lower than the first drive voltage (step S15), and the processing of this flowchart is performed. End and record image. When the ink temperature is higher than 30 ° C., the viscosity of the ink is lowered. Therefore, when the ink is driven with the first driving voltage, there is a possibility that the image quality is deteriorated by increasing the discharge speed or increasing the discharge amount. Therefore, by driving with the third drive voltage lower than the first drive voltage, the discharge speed and the discharge amount are adjusted, and the influence on the image quality due to the change of the ink temperature is reduced.

  As described above, even when image recording is performed when the ink temperature is changed to prevent the ink inside the nozzle 34 from drying and the nozzle surface 33 from dew condensation during the moisture retention of the head 32, the ink temperature By setting the drive voltage according to the above, it is possible to prevent the image quality of the recorded image from being deteriorated.

  Instead of changing the drive voltage, the ejection conditions such as the pulse width of the drive waveform of the piezoelectric element 50 may be changed according to the ink temperature.

  In addition, since the range in which the drive voltage can be changed is limited, the first implementation is performed when the drive voltage reaches the upper limit or the lower limit of the changeable range and cannot be set to the drive voltage according to the ink temperature. Similarly to the form, a warning that there is a concern about the image quality may be displayed.

<Third Embodiment>
FIG. 13 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 10 according to the third embodiment. As shown in FIG. 13, it differs from the block diagram shown in FIG. 8 in that an ink temperature sensor 134 is provided.

  The ink temperature sensor 134 (an example of a discharge liquid temperature measurement unit) is a temperature measurement unit that measures the temperature of the ink. In the present embodiment, the ink temperature sensor 134 is waterproofed and provided at a position where it is immersed in the ink inside the circulation tank 54 (see FIG. 6). Note that the ink temperature sensor 134 may be provided at any position of the ink circulation unit 52, and may be provided inside the head 32, for example.

  The temperature measurement unit 122 causes the ink temperature sensor 134 to measure the ink temperature in accordance with a command from the system controller 100 and acquires the measurement result from the ink temperature sensor 134.

  FIG. 14 is a flowchart showing a moisturizing method for the head 32 according to the present embodiment.

  In the present embodiment, the nozzle surface 33 is covered with the moisture retaining cap 82 (an example of the moisturizing space forming step) is set to the long vacation mode in which the state is maintained for a long period (an example of a period equal to or greater than the threshold period).

  The long term is a period of 64 hours or more and less than 2 weeks as an example. When the user does not use the inkjet recording apparatus 10 for a long period of time, the user can set the inkjet recording apparatus 10 to the long-term vacation mode (an example of a setting process) using the operation unit 128 (an example of a setting unit).

  The ink jet recording apparatus 10 periodically pressurizes and sucks the inside of the nozzle 34 while the long vacation mode is set, and then wipes the nozzle surface 33 by the nozzle surface wiping device 94. Here, this process is performed every 2.5 days.

  Furthermore, the inkjet recording apparatus 10 performs the processing of this flowchart at regular intervals while the long vacation mode is set.

  Here, the ink temperature is maintained at 30 ° C., which is the first temperature, by the temperature adjustment unit 58 (an example of a temperature adjustment step), and the ink circulation inside the head 32 by the ink circulation unit 52 (in the circulation step). As an example, it is assumed that the temperature of the nozzle surface 33 is maintained at 30 ° C., which is the ink temperature.

  When the process of this flowchart is started, first, the temperature measurement unit 122 causes the temperature sensor 83 to measure the cap liquid temperature, and acquires the measurement result from the temperature sensor 83 (step S21, an example of a temperature measurement process).

  Next, the temperature measurement unit 122 causes the ink temperature sensor 134 to measure the ink temperature, and acquires the measurement result from the ink temperature sensor 134 (step S22). When the ink temperature is maintained at a constant temperature by the temperature adjustment unit 58, the adjustment temperature by the temperature adjustment unit 58 may be acquired as the ink temperature. Here, since the ink temperature is maintained at 30 ° C. which is the first temperature by the temperature adjustment unit 58, 30 ° C. is acquired as the ink temperature.

  Next, the determination unit 126 determines whether or not the cap liquid temperature acquired in step S21 is within a desired temperature range at the ink temperature acquired in step S22 (step S23, an example of a determination process).

  The storage unit 124 stores an appropriate relationship (an example of a first relationship) between the ink temperature and the cap liquid temperature so that the humidity of the moisturizing space SP becomes an appropriate humidity at which the ink inside the nozzle 34 is prevented from drying. (An example of a storage process).

  In the first embodiment, the humidity of the moisturizing space SP is maintained within the range of 37 RH% to 65 RH, so that the drying of the ink inside the nozzle 34 and the condensation of the nozzle surface 33 are prevented. Condensation on the surface 33 is allowed, and drying of the ink inside the nozzle 34 is prevented. That is, in this embodiment, the humidity of the moisturizing space SP may be 37 RH% or more.

  Here, the ink temperature acquired in step S22 was 30 ° C. Accordingly, in step S23, the determination unit 126 sets “18.5 ° C. or higher”, which is the range of the cap liquid temperature for the humidity of the moisturizing space SP to be an appropriate humidity when the ink temperature is 30 ° C., as an appropriate relationship. It is determined whether the cap liquid temperature read from the storage unit 124 and the cap liquid temperature acquired in step S21 satisfies the read appropriate relationship, that is, whether the cap liquid temperature is 18.5 ° C. or higher.

  When the cap liquid temperature acquired in step S21 is 18.5 ° C. or higher, the ink temperature control unit 120 stops the ink temperature control by the temperature adjustment unit 58 (an example of stopping the operation, step S24, control process) Example), the process of this flowchart is terminated.

  That is, when the ink temperature is 30 ° C. and the cap liquid temperature is 18.5 ° C. or higher, the humidity of the moisturizing space SP is 37 RH% or higher in order to satisfy the appropriate relationship. Therefore, since it is possible to prevent the ink inside the nozzle 34 from drying, it is determined that the ink temperature control is not necessary, and the ink temperature control is stopped.

  On the other hand, when the cap liquid temperature acquired in step S21 is less than 18.5 ° C., the ink temperature control unit 120 sets the ink temperature by the temperature adjustment unit 58 to the second temperature that is equal to or lower than the first temperature. (Step S25), and the process of this flowchart ends.

  For example, assuming that the cap liquid temperature is 18 ° C., it can be seen that when the ink temperature is 30 ° C., the humidity of the moisturizing space SP is about 35 RH% from the approximate line shown in FIG. Thus, when the ink temperature is 30 ° C. and the cap liquid temperature is 18 ° C., the appropriate relationship is not satisfied, and the humidity of the moisture retaining space SP is less than 37 RH%.

  Here, the ink temperature control unit 120 sets the ink temperature by the temperature adjustment unit 58 to 27 ° C. It can be seen that the humidity of the moisture retention space SP when the ink temperature is 27 ° C. and the cap liquid temperature is 18 ° C. is about 41 RH% from the approximate line shown in FIG. As described above, the humidity of the moisturizing space SP can be set to 37 RH% or more by changing the measured cap liquid temperature to an ink temperature that satisfies an appropriate relationship.

  As described above, the inkjet recording apparatus 10 performs the processing of this flowchart at regular intervals while the long vacation mode is set. When the ink temperature control by the temperature adjustment unit 58 is stopped in step S24, the ink temperature in the subsequent step S22 is acquired from the ink temperature sensor 134.

  Further, in subsequent step S23, the determination unit 126 sets the cap liquid temperature range for the humidity of the moisturizing space SP to be an appropriate humidity at the ink temperature acquired from the ink temperature sensor 134 from the storage unit 124 as an appropriate relationship. read out.

  FIG. 15 is a graph showing an appropriate relationship between the ink temperature and the cap liquid temperature threshold value for causing the humidity of the moisturizing space SP to be an appropriate humidity at which the ink inside the nozzle 34 is prevented from drying. If each ink temperature in FIG. 15 is a cap liquid temperature higher than the corresponding cap liquid temperature threshold, the ink inside the nozzle 34 is prevented from drying. For example, if the ink temperature is 25 ° C., the humidity of the moisturizing space SP is an appropriate humidity at which the ink inside the nozzle 34 is prevented from being dried when the cap liquid temperature is higher than 17 ° C. This relationship is stored in the storage unit 124 in advance.

  When a sufficient amount of time has passed since the ink temperature control was stopped, the ink temperature becomes a temperature corresponding to the ambient temperature of the inkjet recording apparatus 10. Therefore, the ink temperature and the cap liquid temperature are considered to be equal.

  As shown in FIG. 15, when the ink temperature and the cap liquid temperature are both near room temperature, drying of the ink inside the nozzle 34 is prevented. Therefore, even if the ink temperature control is stopped, the humidity of the moisture retaining space SP can be maintained at an appropriate humidity that prevents the ink inside the nozzle 34 from being dried.

  According to the present embodiment, even when the cap liquid temperature changes while the long vacation mode in which the state in which the nozzle surface 33 is covered with the moisturizing cap 82 is set for a long time is set, the moisturizing space SP of the moisturizing space SP is changed. Since the humidity can be maintained at a humidity that prevents the ink inside the nozzle 34 from drying, deterioration of the discharge performance of the discharge head can be prevented.

  Further, in the long-term vacation mode, by allowing condensation on the nozzle surface 33, it is possible to stop the control of the ink temperature when the humidity of the moisturizing space SP is high, so that it is possible to save power in the inkjet recording apparatus 10. . When the long vacation mode is canceled and image recording is performed, the nozzle surface 33 may be condensed, so it is preferable to wipe the nozzle surface 33 with the nozzle surface wiping device 94.

<Relationship with ink types>
In the description so far, the humidity of the moisturizing space SP is set to 65 RH% or less in order to prevent the nozzle surface 33 from condensing. However, when water-based ink containing a solvent that easily absorbs moisture is used, it is necessary to lower the upper limit of the humidity. is there. In this case, the appropriate relationship between the ink temperature and the cap liquid temperature is such that the humidity in the moisturizing space SP becomes an appropriate humidity that prevents drying of the ink inside the nozzle 34 and condensation on the nozzle surface.

  In addition, when water-based ink with an increased amount of high-boiling solvent is used, the ink inside the nozzle 34 becomes difficult to dry, and therefore the lower limit of humidity can be lowered. In addition, in the case of water-based ink using a solvent having a raised boiling point, the ink inside the nozzle 34 is difficult to dry, so the lower limit of humidity can be lowered.

  Further, it can be applied to an ink jet recording apparatus using an ultraviolet curable ink. In the case of using ultraviolet curable ink, an ultraviolet light source is disposed downstream of the head 32 in the conveyance path of the paper 1 by the paper conveyance unit 20, and ultraviolet rays are irradiated on the paper 1 after image recording. The recorded image can be cured.

  Such an ultraviolet curable ink does not absorb moisture, that is, the ultraviolet curable ink does not mix with water, so the upper limit of humidity may be unnecessary. In addition, since UV curable ink is difficult to dry and cure, the lower limit of humidity may be lowered.

<Others>
In the embodiment described so far, for example, the system controller 100, the conveyance control unit 112, the head movement control unit 114, the image recording control unit 116, the circulation control unit 118, the ink temperature control unit 120, the determination unit 126, and the like. The hardware structure of a processing unit that executes processing is the following various processors. For various processors, the circuit configuration can be changed after manufacturing a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), which is a general-purpose processor that functions as various processing units by executing software (programs). Includes a dedicated electrical circuit that is a processor having a circuit configuration specifically designed to execute a specific process such as a programmable logic device (PLD) or ASIC (Application Specific Integrated Circuit) It is.

  One processing unit may be configured by one of these various processors, or may be configured by two or more processors of the same type or different types (for example, a plurality of FPGAs or a combination of CPUs and FPGAs). May be. Further, the plurality of processing units may be configured by one processor. As an example of configuring a plurality of processing units with one processor, first, as represented by a computer such as a server and a client, one processor is configured with a combination of one or more CPUs and software. There is a form in which the processor functions as a plurality of processing units. Second, as represented by a system-on-chip (SoC) or the like, there is a form of using a processor that realizes the functions of the entire system including a plurality of processing units with a single integrated circuit (IC) chip. is there. As described above, various processing units are configured using one or more various processors as a hardware structure.

  Further, the hardware structure of these various processors is more specifically an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Paper 2 Host computer 10 Inkjet recording device 20 Paper conveyance part 22 Belt 30 Image recording part 31 Head support frame 32 Head 32C Head 32K Head 32M Head 32Y Head 33 Nozzle surface 34 Nozzle 35 Head moving mechanism 36 Pressure chamber 38 Ink chamber unit 39 Ink inlet 40 Individual flow path 41 Common flow path 42 Nozzle flow path 43 Individual circulation flow path 44 Circulation common flow path 46 Supply port 47 Discharge port 48 Diaphragm 49 Individual electrode 50 Piezoelectric element 52 Ink circulation part 54 Circulation tank 56 Supply flow Path 58 temperature adjusting unit 60 supply pump 62 recovery channel 64 recovery pump 66 replenishment tank 68 replenishment channel 70 replenishment pump 80 maintenance unit 82 moisture retention cap 82C moisture retention cap 82K moisture retention cap 82M moisture retention cap 82Y moisture retention cap 83 temperature sensor 4 waste tray 86 waste liquid recovery pipe 88 the waste liquid tank 90 the head cleaning portion 92 mount 94C nozzle surface wiping device 94K nozzle surface wiping device 94M nozzle surface wiping device 94Y nozzle surface wiping device 100 the system controller 102 communicating unit 104 CPU
106 ROM
108 RAM
110 Image memory 112 Transport control unit 114 Head movement control unit 116 Image recording control unit 118 Circulation control unit 120 Ink temperature control unit 122 Temperature measurement unit 124 Storage unit 126 Determination unit 128 Operation unit 130 Display unit 132 Non-volatile memory 134 Ink temperature Sensors S1 to S6 Head moisturizing method steps S11 to S15 Image recording condition setting method steps S21 to S24 Head moisturizing method step SP Moisturizing space

Claims (15)

An ejection head for ejecting liquid droplets of ejection liquid from nozzles arranged on the nozzle surface;
A discharge liquid tank for storing the discharge liquid;
A circulation part for circulating the discharge liquid between the discharge liquid tank and the discharge head;
A temperature adjusting unit for adjusting the temperature of the discharged liquid;
A controller that sets the temperature of the discharge liquid adjusted by the temperature adjuster to a first temperature;
Moisturizing cap that stores cap liquid and covers the nozzle surface to form a moisturizing space with the nozzle surface;
A storage unit for storing a first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for the humidity of the moisturizing space to be a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented;
A temperature measuring unit for measuring the temperature of the cap liquid;
A determination unit that determines whether the measured temperature of the cap liquid and the first temperature of the discharged liquid satisfy the first relationship;
With
When the determination unit determines that the first relationship is not satisfied, the control unit sets the temperature of the discharge liquid to a second temperature that satisfies the first relationship at the measured temperature of the cap liquid. Drop ejection device.   2. The droplet discharge device according to claim 1, wherein when the determination unit determines that the first relationship is satisfied, the control unit sets the temperature of the discharge liquid to the first temperature. A medium transport unit for transporting the recording medium;
An image recording unit that discharges ink as the ejection liquid from the nozzle and records an image on the transported recording medium;
The droplet discharge device according to claim 1, further comprising:   The apparatus according to claim 3, further comprising a warning unit that issues a warning that there is a concern about the image quality of the image when the image recording unit records the image in a state where the temperature of the ink is set to a second temperature. Droplet discharge device. The discharge head has a drive element for discharging the discharge liquid from the nozzle,
When the temperature of the discharge liquid is set to the first temperature, the drive element is driven with a first drive voltage,
When the temperature of the discharge liquid is set to a temperature lower than the first temperature, the drive element is driven with a second drive voltage higher than the first drive voltage,
5. The driving element according to claim 1, wherein when the temperature of the discharge liquid is set to a temperature higher than the first temperature, the driving element is driven with a third driving voltage lower than the first driving voltage. 6. The liquid droplet ejection apparatus described. A setting unit for setting a vacation mode in which the state of covering the nozzle surface with the moisturizing cap is maintained for a period longer than a threshold period;
When set to the vacation mode,
The determination unit determines whether the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship at the first temperature of the discharge liquid,
6. The control unit according to claim 1, wherein when the temperature of the measured cap liquid is determined to be higher than the temperature of the cap liquid that satisfies the first relationship, the control unit stops the operation of the temperature adjustment unit. The droplet discharge device according to any one of the above. An ejection head for ejecting liquid droplets of ejection liquid from nozzles arranged on the nozzle surface;
A discharge liquid tank for storing the discharge liquid;
A circulation part for circulating the discharge liquid between the discharge liquid tank and the discharge head;
A temperature adjusting unit for adjusting the temperature of the discharged liquid;
A controller that sets the temperature of the discharge liquid adjusted by the temperature adjuster to a first temperature;
Moisturizing cap that stores cap liquid and covers the nozzle surface to form a moisturizing space with the nozzle surface;
A storage unit for storing a first relationship between the temperature of the discharge liquid and the temperature of the cap liquid for the humidity of the moisturizing space to be a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented;
A setting unit for setting a vacation mode in which the nozzle surface is covered with the moisturizing cap and maintained for a period longer than a threshold period;
A temperature measuring unit for measuring the temperature of the cap liquid;
A determination unit that determines whether the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship at the first temperature of the discharge liquid;
With
When it is determined that the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship, the control unit determines the temperature of the discharge liquid when the vacation mode is not set. Is set to a second temperature that satisfies the first relationship at the measured temperature of the cap liquid and is higher than the first temperature, and when the vacation mode is set, the temperature adjustment unit Droplet ejecting device that stops the operation. A discharge liquid temperature measuring unit for measuring the temperature of the discharge liquid;
The determination unit is configured such that when the operation of the temperature adjustment unit is stopped, the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship in the measured temperature of the discharged liquid. The droplet discharge device according to claim 7, wherein it is determined whether or not.   The liquid droplet ejection apparatus according to claim 1, wherein the temperature measurement unit is disposed outside the moisture retention cap. The circulation part is
A supply flow path communicating the discharge liquid tank and the discharge head;
A supply pump for supplying the discharge liquid stored in the discharge liquid tank to the discharge head via the supply flow path;
A recovery flow path for communicating the discharge head and the discharge liquid tank;
A recovery pump for recovering the discharge liquid inside the discharge head to the discharge head via the recovery flow path;
A droplet discharge device according to claim 1, comprising:   The liquid droplet ejection apparatus according to claim 10, wherein the temperature adjustment unit is provided in the supply channel. The ejection head is
A nozzle supply flow path communicating the supply flow path and the nozzle;
A nozzle recovery flow path communicating the recovery flow path and the nozzle;
A droplet discharge device according to claim 10 or 11, comprising: The first relationship is a relationship that defines a temperature range of the cap liquid so that the humidity of the moisturizing space becomes a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented for each temperature of the discharge liquid. Yes, the higher the temperature of the discharge liquid, the higher the upper limit temperature and the lower limit temperature of the cap liquid temperature range,
The droplet according to any one of claims 1 to 12, wherein the determination unit determines whether the measured temperature of the cap liquid is within the range with respect to the first temperature of the discharge liquid. Discharge device. A circulation step of circulating the discharge liquid between a discharge head for discharging liquid droplets of discharge liquid from a nozzle disposed on the nozzle surface and a discharge liquid tank for storing the discharge liquid;
A temperature adjusting step for adjusting the temperature of the discharged liquid;
A control step of setting the temperature of the discharge liquid adjusted by the temperature adjustment step to a first temperature;
A moisturizing space forming step of forming a moisturizing space between the moisturizing cap and the nozzle surface by covering the nozzle surface with a moisturizing cap storing a cap liquid;
A storage step of storing in the storage unit a first relationship between the temperature of the discharge liquid and the temperature of the cap liquid so that the humidity of the moisturizing space becomes a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented; ,
A temperature measuring step for measuring the temperature of the cap liquid;
A determination step of determining whether the measured temperature of the cap liquid and the first temperature of the discharged liquid satisfy the first relationship;
With
In the control step, when it is determined by the determination step that the first relationship is not satisfied, the discharge liquid temperature is set to a second temperature that satisfies the first relationship in the measured cap liquid temperature. Moisturizing method of the head. A circulation step of circulating the discharge liquid between a discharge head for discharging liquid droplets of discharge liquid from a nozzle disposed on the nozzle surface and a discharge liquid tank for storing the discharge liquid;
A temperature adjusting step for adjusting the temperature of the discharged liquid;
A control step of setting the temperature of the discharge liquid adjusted by the temperature adjustment step to a first temperature;
A moisturizing space forming step of forming a moisturizing space between the moisturizing cap and the nozzle surface by covering the nozzle surface with a moisturizing cap storing a cap liquid;
A storage step of storing in the storage unit a first relationship between the temperature of the discharge liquid and the temperature of the cap liquid so that the humidity of the moisturizing space becomes a humidity at which drying of the nozzle and condensation on the nozzle surface are prevented; ,
A setting step for setting a vacation mode in which the nozzle surface is covered by the moisturizing cap and maintained for a period longer than a threshold period;
A temperature measuring step for measuring the temperature of the cap liquid;
A determination step of determining whether the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship at the first temperature of the discharge liquid;
With
When it is determined that the measured temperature of the cap liquid is higher than the temperature of the cap liquid that satisfies the first relationship, the control step determines the temperature of the discharge liquid when the vacation mode is not set. Is set to a second temperature that satisfies the first relationship in the measured temperature of the cap liquid and is higher than the first temperature, and when the vacation mode is set, the temperature adjustment step Moisturizing method for the discharge head that stops the operation.

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