JP2015039780A - Nozzle surface moisture retention device, liquid discharge device, and nozzle surface moisture retention method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle surface moisture retention device which maintains a constant moisture retention state of a nozzle surface of an ink jet head, and to provide a liquid discharge device and a nozzle surface moisture retention method.SOLUTION: A nozzle surface moisture retention device retains moisture on a nozzle surface 122 of a liquid discharge head 120 and includes: a moisture retention cap 140 including a liquid accumulation part 142 for accumulating a moisturizer 144 and a sealing member 146 which maintains the sealability in a shorter direction of the liquid discharge head 120 between the liquid accumulation part 142 and the liquid discharge head 120 and forms opening parts 148a, 148b at both ends in a longer direction of the liquid discharge head 120; airflow generation means 190 which generates flow of air supplied from the one opening part 148a and exhausted from the other opening part 148b; and a plane member 126 provided at the side of the one opening part which supplies the air.

Description

  The present invention relates to a nozzle surface moisturizing device, a liquid ejecting apparatus, and a nozzle surface moisturizing method, and more particularly to a nozzle surface moisturizing device, a liquid ejecting apparatus, and a nozzle surface moisturizing method that prevent drying of the nozzle surface during standby of a liquid ejection head. .

  In recent years, there has been an increasing demand for small number of copies in the printing industry. In offset printing, since it is necessary to create a plate, when printing a small number of copies, there has been a problem in terms of time and cost. For this reason, single-pass inkjet recording is preferably used.

  Further, in the ink jet recording apparatus, it is necessary to prevent the ink in the nozzles from drying. For this reason, during standby, the nozzle surface of the ejection head is covered with a moisturizing cap in which moisturizing liquid is stored, and the humidity in the vicinity of the nozzle is maintained in a desired range by the evaporation of the moisturizing liquid.

  For example, Patent Document 1 below includes cap means that covers a discharge space facing a discharge surface in which a plurality of discharge ports are formed, with a first opening and a second opening, and includes a first opening and a second opening. It is described that humidified air is alternately supplied, the humidity of the discharge space is made uniform in a short time, and the discharge surface is moisturized. Patent Document 2 includes a first moisturizing unit that uses a moisturizing liquid and a second moisturizing unit that uses a liquid for ejection discharged from a liquid ejection head, and the moisturizing liquid in the first moisturizing unit is used up. Describes a liquid ejecting apparatus that maintains the inside of the head cap in an appropriate moisturizing state by the second moisturizing unit.

JP2013-10300A JP 2001-18408 A

  However, the actual situation is that there is a humidity difference between the high-humidity air supplied into the discharge space and the liquid in the discharge port (moisture is transferred between the air and the liquid). In some cases, it is desired to supply water to the liquid having increased viscosity near the discharge port to suppress clogging of the discharge port. In the liquid discharge apparatus described in Patent Document 1, the humidity near the supply port of the discharge port becomes the desired humidity in a short time, but in order to set the humidity near the discharge port to the desired humidity, the entire discharge space is uniform. It needed to be humidified and took a long time.

  Further, in the liquid ejecting apparatus described in Patent Document 2, if the replacement of the moisturizing liquid cartridge and the replacement of the ink cartridge cannot be performed at the same time, there is a problem that the replacement frequency increases and the burden on the user increases. .

  The present invention has been made in view of such circumstances, and with a simple mechanism, a nozzle surface moisturizing device, a liquid ejecting device, and a liquid ejection device capable of maintaining a constant moisturizing state when moisturizing the nozzle surface of an inkjet head An object of the present invention is to provide a nozzle surface moisturizing method.

  In order to achieve the above object, the present invention is a nozzle surface moisturizing device that moisturizes the nozzle surface of a liquid ejection head, a liquid reservoir for storing a moisturizing liquid provided facing the nozzle surface, and a liquid reservoir. A moisture-retaining cap that maintains a short-side sealability of the liquid discharge head and forms an opening at both ends in the longitudinal direction between the liquid discharge head and a moisture retaining cap for moisturizing the nozzle surface An air flow generating means for generating a flow of air supplied from one opening in the longitudinal direction of the liquid discharge head and discharged from the other opening, and one opening side for supplying air generated by the air flow generating means And a planar member provided to face the liquid reservoir.

  According to the present invention, the liquid discharge head and the moisturizing cap are mounted, and a unidirectional air flow is generated between the nozzle surface of the liquid discharge head and the moisturizing cap, whereby the moisturizing liquid in the liquid reservoir is The evaporated air can be flowed, and the humidity of the nozzle surface can be maintained constant. In addition, by having a flat member provided opposite to the liquid reservoir on the one opening side that supplies air, the position changes to sufficiently moisturized air by the moisturizing distribution between the nozzle surface and the moisturizing cap. Since the nozzle surface can be provided, the nozzle surface can be moisturized at a desired humidity.

  The nozzle surface moisturizing device according to another aspect of the present invention is the length of the planar member so that the humidity distribution of the moisturizing space formed by the nozzle surface and the planar member, and the moisture retaining cap becomes the moisture retaining humidity at the nozzle surface. Is preferably adjusted.

  According to the nozzle surface moisturizing device according to another aspect of the present invention, air is not sufficiently moisturized near the opening to which air is supplied, but the nozzle surface is adjusted by adjusting the length of the planar member. The nozzle surface can be moisturized with air of moisturizing humidity from the formed position. The “moisturizing humidity” is a humidity at which the nozzle surface can be moisturized, and is appropriately determined depending on the apparatus configuration, the moisturizing liquid, and the liquid ejected from the liquid ejection head.

  In the nozzle surface moisturizing device according to another aspect of the present invention, the planar member is preferably provided in the liquid ejection head.

  According to the nozzle surface moisturizing device according to another aspect of the present invention, the planar member is bonded to the liquid ejection head, so that the moisturizing space can be formed by attaching the moisturizing cap and the liquid ejection head. The nozzle surface can be moisturized at a desired humidity.

  In the nozzle surface moisturizing device according to another aspect of the present invention, the planar member is preferably provided on the moisturizing cap.

  According to the nozzle surface moisturizing device according to another aspect of the present invention, since the planar member is formed on the moisturizing cap, the device can be miniaturized.

  In the nozzle surface moisturizing device according to another aspect of the present invention, the clearance between the nozzle surface and the moisturizing liquid and the clearance between the planar member and the moisturizing liquid are preferably equal.

  According to the nozzle surface moisturizing apparatus according to another aspect of the present invention, since the clearance between the nozzle surface and the moisturizing liquid and the clearance between the planar member and the moisturizing liquid are equal, the humidity distribution can be easily obtained.

  In the nozzle surface moisturizing device according to another aspect of the present invention, the sealing member is preferably an elastic member, and the elastic member is preferably in contact with the liquid ejection head.

  According to the nozzle surface moisturizing device according to another aspect of the present invention, the sealing performance can be improved by bringing the liquid discharge head and the protective cap into contact with each other by the elastic member. Therefore, it is possible to prevent air from leaking from locations other than the opening, and to maintain the humidity in the moisturizing space.

  In the nozzle surface moisturizing device according to another aspect of the present invention, the sealing member may have a labyrinth structure in which the first member provided in the liquid ejection head and the second member provided in the moisturizing cap are combined. preferable.

  According to the nozzle surface moisturizing device according to another aspect of the present invention, the labyrinth structure is a combination of the first member provided in the liquid ejection head and the second member provided in the moisturizing cap. Holds sex. By setting it as a labyrinth structure, it can prevent that the air in moisture retention space leaks outside. Further, since air flows in one direction by the airflow generating means in the moisture retaining space, the desired humidity can be maintained without air leaking.

  In order to achieve the above object, the present invention provides a liquid discharge head having a nozzle surface on which a plurality of nozzles for discharging liquid are arranged, and an image forming position at which the liquid discharge head discharges liquid to form an image on a medium. A liquid discharge apparatus comprising: a moving position for moving the liquid discharge head; and a nozzle surface moisturizing device provided at the standby position, wherein the liquid discharge head does not perform the image formation. provide.

  According to the present invention, it is possible to obtain the same effect as the nozzle surface moisturizing device described above, and it can be suitably used as a liquid ejection device.

  In order to achieve the above object, the present invention provides a nozzle surface moisturizing method for moisturizing the nozzle surface of a liquid discharge head, the liquid reservoir for storing a moisturizing liquid provided facing the nozzle surface, and the liquid reservoir A moisturizing cap having a sealing member that maintains an airtight seal in the short direction of the head and forms openings at both ends in the longitudinal direction between the liquid discharge head and the liquid discharge head One opening part which has a process and a ventilation process which blows air from one opening part of the longitudinal direction of the liquid discharge head to the other opening part, and supplies air sent by the ventilation process There is provided a nozzle surface moisturizing method having a planar member provided on the side facing the liquid reservoir, and adjusting the humidity of the nozzle surface by adjusting the length of the planar member in the longitudinal direction.

  In the nozzle surface moisturizing method according to another aspect of the present invention, the sealing member is preferably an elastic member, and in the mounting step, the elastic member is preferably brought into contact with the liquid ejection head.

  In the nozzle surface moisturizing method according to another aspect of the present invention, the mounting step combines a labyrinth structure including a first member provided in the liquid ejection head and a second member provided in the moisturizing cap. Is preferred.

  According to the nozzle surface moisturizing method of the present invention, the same effect as the nozzle surface moisturizing device can be obtained.

  According to the nozzle surface moisturizing device, the liquid ejection device and the nozzle surface moisturizing method of the present invention, when the nozzle surface is moisturized with the moisturizing cap, the plane member is provided on the air supply side. After that, the nozzle surface can be moisturized. Therefore, a desired humidity state can be maintained and the nozzle surface can be moisturized.

  In addition, since air in a constant direction is supplied by the airflow generation means, for example, moisture retention due to disturbances such as turbulence and convection caused by fans and heat such as the paper feed, impression cylinder, and paper discharge section of the liquid ejection device The influence on the flow path in the cap can be suppressed. Therefore, it can be set as a robust design.

  In addition, since the nozzle surface can be maintained at a desired humidity only with the moisturizing cap that stores the moisturizing liquid in this way, the mechanism can be simplified and effective in terms of cost, assembly, and maintenance. Can be implemented.

It is a side view which shows an inkjet recording device. It is a top view of an inkjet recording device. It is a plane perspective view which shows the structural example of an inkjet head. It is sectional drawing which shows the three-dimensional structure of an ink chamber unit. It is a flow-path block diagram which shows the flow-path structure inside a head module. It is a block diagram which shows the system configuration | structure of an inkjet recording device. It is the figure which showed typically the inkjet head and moisture retention cap of a standby position. It is a schematic diagram of the inkjet head equipped with the moisture retention cap. It is sectional drawing of FIG. It is a graph which shows the distance from an air supply side, and the humidity of the nozzle surface vicinity. It is a figure which shows the humidity distribution of moisture retention space. It is the figure which showed typically the inkjet head and moisture retention cap which concern on 2nd Embodiment. It is sectional drawing of the inkjet head and moisture retention cap which concern on 3rd Embodiment. It is a side view which shows the structure of the principal part of an inkjet recording device. It is a top view which shows the structure of the principal part of an inkjet recording device. It is an enlarged view of a head unit. It is the figure which showed the moisture retention unit and the head unit typically.

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

<First Embodiment>
[Outline of inkjet recording apparatus]
FIG. 1 is a side view showing an ink jet recording apparatus (an example of a liquid ejection apparatus) according to the present embodiment. The inkjet recording apparatus 100 ejects ink from a nozzle surface 122 of an inkjet head 120 (an example of a liquid ejection head) onto a recording surface of a sheet (an example of a medium) 1 that is conveyed in a horizontal direction (Y direction) by a conveyance unit 110. Thus, the printer forms an image.

  FIG. 2 is a plan view of the ink jet recording apparatus 100. The ink jet recording apparatus 100 includes a moisturizing cap 140 in a direction (X direction) orthogonal to the transport direction (Y direction) of the paper 1 by the transport unit 110.

  The inkjet head 120 is held by a head holding unit 130 and is configured to be movable in the X direction by a moving mechanism (an example of moving means) (indicated by reference numeral 160 in FIG. 6). When the apparatus is stopped for a long time, the inkjet head 120 is moved from a position where an image can be formed on the paper 1 (image forming position) to a position (standby position) of the moisturizing cap 140, and the nozzle surface 122 is moved to the moisturizing cap 140. Covered with. Thereby, non-ejection due to drying is prevented.

  When the ink jet head 120 moisturizes the nozzle surface 122 with the moisturizing cap 140, the nozzle area (shown with reference numeral 51 in FIG. 3) having nozzles on the nozzle surface 122 (shown with reference numeral 124 in FIG. 7). A non-nozzle region (illustrated with reference numeral 126 in FIG. 7) (an example of a planar member) is provided in order to bring the state shown in FIG. In the first embodiment, the nozzle area and the non-nozzle area are formed in the same plane, and the presence or absence of the nozzle is different. At the image forming position, as shown in FIG. 2, the nozzle area is arranged on the paper 1.

[Configuration of inkjet head]
FIG. 3 is a diagram illustrating a structure example of the inkjet head 120. Here, FIG. 3A is a plan perspective view seen from the nozzle surface 122 side, FIG. 3B is an enlarged view of a part thereof, and FIG. 3C is composed of a head module 120a. It is a plane perspective view of the whole inkjet head 120 to be performed. 4 is a cross-sectional view showing a three-dimensional configuration of the ink chamber unit (a cross-sectional view taken along line 4-4 in FIGS. 3A and 3B). FIG. FIG. 5 is a flow channel configuration diagram (plan view seen from five directions in FIG. 4) showing a flow channel structure. 3 to 5, the head module 120a that forms the nozzle region 124 of the inkjet head 120 is illustrated and described, and the head module that forms the non-nozzle region 126 is omitted.

  The nozzle surface 122 of the inkjet head 120 is formed in a flat surface. A plurality of nozzles 51 that are ink droplet ejection holes are arranged on the nozzle surface 122. In order to increase the dot pitch formed on the paper 1, it is necessary to increase the nozzle pitch. As shown in FIGS. 3A and 3B, the inkjet head 120 according to the present embodiment includes a plurality of ink chamber units 53 including pressure chambers 52 corresponding to the nozzles 51 in a matrix with a fixed arrangement pattern. It has a (two-dimensional) arrangement. This achieves a high density of substantial nozzle intervals (projection nozzle pitch) projected so as to be aligned along the head longitudinal direction (X direction).

  Further, as shown in FIG. 3C, a long inkjet head 120 having a nozzle row having a length corresponding to the full width of the paper is configured by arranging short head modules 120a in a staggered manner and connecting them together. May be. Although illustration is omitted, a long inkjet head may be configured by arranging short head modules in a line.

  In addition, the form which comprises one or more nozzle rows over a length corresponding to the full width of the paper in a direction substantially orthogonal to the paper transport direction is not limited to this example.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the ink inlet 54 are provided at both corners on the diagonal line. Each pressure chamber 52 is communicated with an individual flow path 59 via an ink inlet 54, and each individual flow path 59 is communicated with a common flow path 55. Further, the nozzle flow path 60 communicating with each pressure chamber 52 is communicated with the circulation common flow path 64 via the individual circulation flow path 62. The ink jet head 120 is provided with a supply port 66 and a discharge port 68. The supply port 66 communicates with the common flow channel 55, and the discharge port 68 communicates with the circulation common flow channel 64.

  That is, the supply port 66 and the discharge port 68 of the ink jet head 120 include a common channel 55, an individual channel 59, an ink inlet 54, a pressure chamber 52, a nozzle channel 60, an individual circulation channel 62, and a circulation common channel. 64 is configured to communicate with each other via an ink flow path (internal flow path) including 64. For this reason, a part of the ink supplied from the outside of the inkjet head 120 to the supply port 66 is ejected from each nozzle 51, and the remaining ink is common flow channel 55, individual flow channel 59, nozzle flow channel 60, individual flow. The ink is discharged from the discharge port 68 to the outside of the inkjet head 120 through the circulation flow path 62 and the circulation common flow path 64 in order.

  As shown in FIG. 4, a configuration in which the individual circulation flow path 62 is connected in the vicinity of the nozzle 51 of the nozzle flow path 60 is preferable, and the ink circulates in the vicinity of the nozzle 51. It is prevented and stable discharge becomes possible.

  A piezoelectric element 58 having an individual electrode 57 is joined to a diaphragm 56 that constitutes the top surface of the pressure chamber 52 and also serves as a common electrode. By applying a driving voltage to the individual electrode 57, the piezoelectric element 58 is Deformation causes ink to be ejected from the nozzle 51. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the individual channel 59 and the ink inlet 54.

  In this example, the piezoelectric element 58 is applied as a means for generating ink ejection force to be ejected from the nozzle 51 provided in the inkjet head 120. However, a heater is provided in the pressure chamber 52, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method for discharging ink.

  As shown in FIG. 3B, the ink chamber unit 53 having such a structure has a constant arrangement pattern along a direction along the head longitudinal direction and an oblique row direction having a constant angle θ not orthogonal to the head longitudinal direction. Thus, the high-density nozzle head of this example is realized by arranging a large number in a grid pattern.

  That is, with the structure in which a plurality of ink chamber units 53 are arranged at a constant pitch P along the direction of an angle θ with respect to the head longitudinal direction, the pitch PX of the nozzles projected so as to be aligned in the head longitudinal direction is P × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch PX. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the present embodiment, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the lateral direction of the head can be applied.

[System configuration of inkjet recording apparatus]
FIG. 6 is a block diagram illustrating a system configuration of the inkjet recording apparatus 100. As shown in the figure, the ink jet recording apparatus 100 includes an ink circulation unit 150, a moving mechanism 160, a user interface 172, a recording control unit 174, and an ink circulation control in addition to the above-described transport unit 110, ink jet head 120, and moisture retention cap 140. 176, a movement control unit 178, a moisturizing liquid control unit 180, an airflow control unit 182 and the like.

  The ink circulation unit 150 includes pipes, valves, ink tanks, pumps, and the like (not shown), and is connected to the inkjet head 120 via the valves. The ink circulation unit 150 supplies ink ejected from the nozzles 51 of the inkjet head 120 from the supply port 66 of the inkjet head 120. Further, the nozzles that have not been ejected from the nozzles are collected from the discharge port 68, and the ink is circulated between the inkjet head 120 and the ink tank.

  The ink circulation unit 150 circulates the ink so that the back pressure of the nozzle 51 (internal pressure of the inkjet head 120) becomes negative. Here, the negative pressure refers to a pressure smaller than atmospheric pressure.

  The moving mechanism 160 moves the inkjet head 120 to the image forming position or the standby position. Further, as will be described later, the moving mechanism 160 is configured to be able to change the distance between the inkjet head 120 and the moisturizing cap 140.

  The user interface 172 includes a power switch for turning on (conducting) / off (cutting off) the power of the inkjet recording apparatus 100, an input unit (not shown) for the user to operate the inkjet recording apparatus 100, a warning display, and the like. Has an output unit (not shown).

  The recording control unit 174 controls the conveyance of the paper 1 by the conveyance unit 110, the ejection of ink by the inkjet head 120, and the like, and forms an image on the recording surface of the paper 1 based on the input image data.

  The ink circulation control unit 176 controls the ink circulation unit 150 to control the presence / absence of ink circulation to the inkjet head 120 and the circulation ink amount.

  The movement control unit 178 controls the movement mechanism 160 and controls the position of the inkjet head 120.

  The moisturizing liquid control unit 180 controls supply / discharge of the moisturizing liquid in the moisturizing cap 140.

  The airflow control unit 182 controls the flow of air using a fan (shown with reference numeral 190 in FIG. 7), and in the mounted state in which the moisturizing cap 140 is mounted on the inkjet head 120, the airflow control unit 182 The air flow in the moisturizing space between the cap 140 and the moisturizing liquid is controlled.

<Composition of moisture retention cap>
FIG. 7 is a diagram schematically showing the moisturizing cap 140 and the inkjet head 120 moved to the standby position (humidity retaining position). 8A is a diagram in which the inkjet head 120 is mounted on the moisture retention cap 140, FIG. 8B is an enlarged view of the air supply side of FIG. 8A, and FIG. 8C is FIG. 9) is an enlarged view of the air discharge side, and FIG. 9 is a cross-sectional view of FIG.

  A liquid reservoir 142 is provided inside the moisturizing cap 140, and the liquid reservoir 142 is filled with a moisturizing liquid 144 for moisturizing the nozzle surface 122 of the inkjet head 120. The moisturizing liquid 144 is a liquid containing the same solvent as the solvent of the ink ejected from the nozzles 51 of the inkjet head 120, and is a liquid mainly composed of water, for example.

  As shown in FIG. 8A, when the inkjet head 120 is attached to the moisture retaining cap 140, the nozzle surface 122 of the inkjet head 120 is disposed at a position facing the liquid reservoir 142. That is, the nozzle region 124 and the non-nozzle region 126 and the liquid reservoir 142 are arranged to face each other.

  The moisture retention cap 140 is provided with a seal member 146 (an example of a sealing member) along the longitudinal direction of the inkjet head 120, and the seal member 146 comes into contact with the inkjet head 120, thereby shortening the inkjet head 120. The hand direction is sealed with a moisturizing cap 140 (along the longitudinal side surface). As the seal member 146, an elastic member can be used, for example, silicone rubber can be used.

  When the moisturizing cap 140 is attached, an opening is provided in the longitudinal direction of the inkjet head 120. FIG. 8B shows one opening 148a in the longitudinal direction, and FIG. 8C shows the other opening 148b in the longitudinal direction. In the present embodiment, wind is blown by the fan 190 (an example of an airflow generating means) from the opening 148a on the side of FIG. 8B toward the opening 148b on the side of FIG. 8C. Note that the openings 148a and 148b do not need to have different structures in particular, and can have the same configuration.

  FIG. 9 is a cross-sectional view of the inkjet head 120 in a state in which the moisture retention cap 140 of FIG. When the moisturizing cap 140 is attached, it is sealed with a seal member 146, and the moisturizing state of the moisturizing space between the nozzle surface 122 and the moisturizing liquid 144 in the moisturizing cap 140 leaks from the longitudinal side surface of the inkjet head 120. Can be prevented. Therefore, in the moisturizing state, air can be taken out from the other opening 148b by flowing air from one opening 148a in the longitudinal direction, so that the moisturizing space can be kept at a constant humidity.

  The clearance H between the nozzle surface 122 and the moisturizing liquid 144 when the moisturizing cap 140 is attached is not particularly limited, but is preferably 2 mm or less. If the distance of the clearance H is long, the humidity of the moisturizing space is not stable, and if the distance of the clearance H is short, the nozzle surface 122 and the moisturizing liquid 144 may come into contact with each other. The clearance H between the nozzle region 124 and the moisturizing liquid 144 and the clearance H between the non-nozzle region 126 and the moisturizing liquid 144 are preferably the same height. If the height is different, the location where the air does not flow may occur, and the humidity may not be stable. However, by using the same height, the air can flow in one direction in the moisturizing space and the humidity can be stabilized. .

  By supplying air from the opening 148a to the moisturizing space constituted by the nozzle surface 122 of the inkjet head 120, the moisturizing cap 140, and the moisturizing liquid 144, the humidity in the moisturizing space is kept constant. In FIG. 6, the fan 190 is used as the airflow generating means for supplying air, but it is possible to generate a flow of air supplied from one opening 148a and discharged from the other opening 148b. There is no particular limitation. For example, a one-way air flow can be generated in the moisturizing space in the moisturizing cap 140 by generating an air flow using a pump or the like. The wind speed of the air supplied into the moisturizing cap 140 is not particularly limited as long as the humidity of the nozzle region 124 can be maintained at a predetermined humidity or higher, but may be 0.3 m / s or more and 0.6 m / s or less. preferable.

  In an inkjet recording apparatus, disturbances such as turbulence and convection occur near the apparatus due to fan and heat, such as paper feed, conveyance, and paper discharge. Therefore, the moisture retention during standby of the inkjet head 120 due to the influence of this disturbance It was difficult to keep the state constant. According to the present embodiment, the humidity of the nozzle surface 122 can be kept constant by flowing constant air through the moisture retaining cap 140.

  The length of the non-nozzle region 126 is adjusted as follows so that the humidity distribution in the moisturizing space formed by the nozzle surface 122 and the non-nozzle region 126 and the moisturizing cap 140 becomes the moisturizing humidity at the nozzle surface 122. .

  FIG. 10 is a diagram showing the relationship between the position of the nozzle surface actually measured from the air supply side opening and the humidity. FIG. 10B shows the humidity distribution when air is supplied at a wind speed of 0.3 m / sec from the opening 148a toward the opening 148b in FIG. At this time, the humidity of the air near the ink jet recording apparatus 100 is about 40% Rh. As shown in FIG. 10B, the humidity exceeds 80% Rh at a point of about 300 mm from the inlet side. Thus, the length of the non-nozzle region 126 is determined at the time of design so that the humidity of the nozzle surface 122 when the moisturizing cap 140 is mounted is obtained by actually measuring and the nozzle region 124 has a desired humidity. . The desired humidity of the nozzle region 124 at the time of moisture retention is preferably 80% Rh or more. Note that the length of the non-nozzle region 126 can be obtained by simulation in addition to the actual measurement.

  FIG. 11 is a diagram illustrating the humidity distribution on the air supply side of the moisturizing space formed by the inkjet head 120 and the moisturizing cap 140. The area (1) in FIG. 11 is humidity 100% Rh, the area (1) is 95% Rh, the area (3) is 90% Rh, and the area (4) is 80% Rh. On the air supply side, the humidity is 100% Rh in the vicinity of the interface with the moisturizing liquid 144 in the moisturizing space, but it is provided at a position facing the moisturizing liquid 144 by supplying low humidity air into the moisturizing space. In the vicinity of the nozzle surface 122, the humidity is low. As the air travels in the moisturizing space, the humidity of 80% Rh or more can be maintained near the nozzle surface 122 due to the diffusion phenomenon of water vapor evaporated from the moisturizing liquid 144. By providing the nozzle region 124 of the nozzle surface 122 from a position where the humidity 80% Rh can be maintained, the humidity of the nozzle surface 122 can be maintained.

  When obtaining the humidity distribution in the moisturizing space, it can be determined by the clearance H, the wind speed of the blown air, and the like. Among these, clearance H and wind speed are particularly important parameters.

<Second Embodiment>
In the first embodiment, by providing a non-nozzle region 126 in which nozzles are not formed on the inkjet head 120 as a planar member until the moisture retention space reaches a desired humidity, the nozzle region 124 has a desired humidity. I am doing so. In the second embodiment, as shown in FIG. 12, the planar member 328 has the same height as the nozzle surface 322 (nozzle region 324) when the inkjet head 320 is mounted on the air supply side of the moisturizing cap 140. Is provided. By providing the planar member 328, the moisturizing state of the moisturizing space between the nozzle surface 322 and the moisturizing liquid 144 facing the nozzle surface 322 can be set to a desired state, as in the first embodiment. In the second embodiment, the flat member 328 and the moisture retention cap 140 form one opening 348a, and the other opening is similar to the inkjet head 320 and the moisture retention as in the first embodiment. The other opening 348 b is formed with the cap 140.

<Third Embodiment>
The third embodiment is different from the first embodiment in that the short-side joint between the inkjet head 420 and the moisture retention cap 440 is not sealed. FIG. 13 is a cross-sectional view of the inkjet head 420 showing a state in which the moisture is retained by the moisture retention cap 440 according to the third embodiment. As shown in FIG. 13, a labyrinth structure in which the first member 448 provided in the inkjet head 420 and the second member 446 provided in the moisture retention cap 440 are combined without completely sealing the short-side direction, It is possible to prevent the air in the moisturizing space from leaking by adopting a configuration in which the moisturizing space and the outside air do not easily come into contact with each other. As in the first embodiment, even if the short direction of the inkjet head is not sealed, air can be flowed by supplying air from the opening 148a and discharging it from the opening 148b. Leakage can be prevented. Therefore, the humidity of the moisturizing space can be maintained, and the humidity of the nozzle surface 422 can be maintained.

<Fourth Embodiment>
[Configuration of inkjet recording apparatus]
Next, an ink jet recording apparatus according to the fourth embodiment will be described.

  FIG. 14 is a side view showing a configuration of a main part of the ink jet recording apparatus according to the present embodiment, and FIG. 15 is a top view. As shown in FIGS. 14 and 15, the inkjet recording apparatus 200 is a single-pass line printer, and mainly includes a conveyance drum 210 that conveys a sheet 1 that is a recording medium, and a sheet 1 that is conveyed by the conveyance drum 210. Head unit 220 that ejects ink droplets of cyan (C), magenta (M), yellow (Y), and black (K), and a moisturizing unit 240 that moisturizes each inkjet head mounted on the head unit 220. It is configured with. The transport drum 210 is driven to rotate by a motor (not shown). A gripper (not shown) is provided on the outer peripheral surface of the transport drum 210, and the paper 1 is transported while the front end is gripped by the gripper. In addition, a large number of suction holes (not shown) are formed on the outer peripheral surface of the transport drum 210, and air is sucked inward from the suction holes. The sheet 1 is conveyed while being sucked and held in the suction holes.

  The head unit 220 includes inkjet heads 220C, 220M, 220Y, and 220K that discharge cyan, magenta, yellow, and black ink droplets, a head holding unit 230 to which the inkjet heads 220C, 220M, 220Y, and 220K are attached, and a head. It is comprised with the moving mechanism (not shown) which moves the holding | maintenance part 230. FIG.

  The nozzle surfaces of the inkjet heads 220C, 220M, 220Y, and 220K are configured by line heads corresponding to the maximum paper width (width in the X direction) of the paper 1 that is an image formation target. In addition, a planar member for controlling the humidity of the moisturizing space when the moisturizing unit 240 is attached is provided in the inkjet head.

  Each inkjet head 220C, 220M, 220Y, 220K is formed in a rectangular block shape, and nozzle surfaces 222C, 222M, 222Y, 222K are formed on the bottom thereof. Further, the number of nozzles formed on the nozzle surfaces 222C, 222M, 222Y, and 222K and the arrangement form thereof are not particularly limited. The inkjet heads 220C, 220M, 220Y, and 220K discharge ink from the nozzles by a piezo method or a thermal method.

  The head holding unit 230 includes a head mounting portion (not shown) for mounting the inkjet heads 220C, 220M, 220Y, and 220K. Each inkjet head 220C, 220M, 220Y, 220K is detachably attached to the head attachment portion.

The inkjet heads 220C, 220M, 220Y, and 220K attached to the head holding unit 230 are disposed orthogonal to the paper 1 transport direction (Y direction). Also,
Arranged at a predetermined interval in a predetermined order along the conveyance direction of the sheet 1. In this embodiment, cyan, magenta, yellow, and black are arranged in this order.

  The inkjet heads 220C, 220M, 220Y, and 220K are attached to the head holding unit 230 so that the nozzle surfaces 222C, 222M, 222Y, and 222K are parallel to the tangent line of the peripheral surface of the conveying drum 210 that faces each other. ing.

FIG. 16 is an enlarged view of the head unit 220. As shown in the figure, the angles formed by the nozzle surfaces 222C, 222M, 222Y, 222K and the horizontal plane are θ _C , θ _M , θ _Y , θ _K , respectively.

  The head mounting portion is provided on the head holding portion 230 so as to be lifted and lowered by a lifting mechanism (not shown). The inkjet heads 220C, 220M, 220Y, and 220K attached to the head attaching portion are moved up and down vertically by the lifting mechanism.

  The moving mechanism slides the head holding unit 230 horizontally in the X direction. The moving mechanism includes a ceiling frame installed horizontally across the transport drum 210 and the moisture retention unit 240, a guide rail laid on the ceiling frame, a traveling body that slides on the guide rail, and the traveling body. It is comprised by the drive means (for example, feed screw mechanism etc.) moved along a guide rail. The head holding unit 230 is attached to the traveling body and slides horizontally.

  The head holding unit 230 is driven by the moving mechanism and is provided so as to be movable between an “image forming position” and a “standby position”.

  When the head holding unit 230 is positioned at the image forming position, the head holding unit 230 is disposed above the transport drum 210. As a result, it is possible to record an image by ejecting ink of each color onto the recording surface of the sheet 1 conveyed by the conveying drum 210.

  On the other hand, when it is located at the standby position (humidity retention position), it is disposed at the installation position of the moisture retention unit 240.

[Composition of moisturizing cap]
FIG. 17 is a diagram schematically showing the moisturizing unit 240 and the head unit 220 moved to the moisturizing position.

  The moisturizing unit 240 includes moisturizing caps 240C, 240M, 240Y, and 240K for moisturizing the nozzle surfaces 222C, 222M, 222Y, and 222K of the inkjet heads 220C, 220M, 220Y, and 220K, respectively.

  Moisturizing liquids 242C, 242M, and 242Y for moisturizing the nozzle surfaces 222C, 222M, 222Y, and 222K of the inkjet heads 220C, 220M, 220Y, and 220K are disposed inside the liquid retention caps (240C, 240M, 240Y, and 240K). , 242K is satisfied.

  Each of the moisturizing caps 240C, 240M, 240Y, and 240K has an opening surface that is horizontally provided, and the ink jet heads 220C, 220M, 220Y, and 220K have the opening portions of the moisturizing caps 240C, 240M, 240Y, and 240K, respectively. By being inserted obliquely, the sealing members 246C, 246M, 246Y, and 246K provided at the openings of the respective moisture retention caps are sealed at the side surfaces of the inkjet heads 220C, 220M, 220Y, and 220K, and the inkjet head heads 220C and 220M are sealed. , 220Y, 220K, and the moisturizing spaces between the moisturizing liquids 242C, 242M, 242Y, 242K and the nozzle surfaces 222C, 222M, 222Y, 222K. The ink jet heads 220C, 220M, 220Y, and 220K and the moisturizing caps 240C, 240M, 240Y, and 240K are attached in the short direction by joining the side surfaces of the ink jet head and the moisturizing cap as in the first embodiment. Alternatively, the gap may be narrowed to form a labyrinth structure as in the third embodiment.

  Further, since the liquid surfaces of the moisturizing liquids 242C, 242M, 242Y, and 242K inside the respective moisturizing caps 240C, 240M, 240Y, and 240K are horizontal, the liquid surfaces of the moisturizing liquids 242C, 242M, 242Y, and 242K and the nozzle surfaces 222C, 222M, 222Y, and 222K are not parallel. However, as described above, each of the moisturizing caps 240C, 240M, 240Y, and 240K improves the sealing performance of the nozzle surfaces 222C, 222M, 222Y, and 222K of the inkjet heads 220C, 220M, 220Y, and 220K. Humidity is high and can be maintained. Further, considering that the liquid surface of the moisturizing liquid and the nozzle surfaces 222C, 222M, 222Y, and 222K are not parallel at the time of designing, the humidity of the nozzle surfaces 222C, 222M, 222Y, and 222K is set to a desired humidity. Thus, the nozzle surfaces 222C, 222M, 222Y, and 222K can be set to a desired humidity by designing the positions of the nozzle surfaces 222C, 222M, 222Y, and 222K on which the nozzles are provided and the non-nozzle surfaces.

  In this specification, an inkjet recording apparatus that discharges colored ink suitable for graphic printing has been described as an example. However, a resist ink (heat-resistant coating material) for printed wiring and conductive fine particles are dispersed in a dispersion medium. The present invention can be applied to an image forming apparatus that ejects ink used for manufacturing a dispersion liquid and a color filter.

  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, 51 ... Nozzle, 100, 200 ... Inkjet recording device, 120, 220C, 220M, 220Y, 220K, 320, 420 ... Inkjet head, 122, 222C, 222M, 222Y, 222K ... Nozzle surface, 140, 240C, 240M, 240Y, 240K ... moisturizing cap, 142 ... liquid reservoir, 144, 242C, 242M, 242Y, 242K ... moisturizing liquid, 146, 246C, 246M, 246Y, 246K ... seal members, 148a, 148b, 348a, 348b ... openings , 328 ... planar member, 446 ... first member, 448 ... second member

Claims (11)

A nozzle surface moisturizing device that moisturizes the nozzle surface of a liquid discharge head,
A liquid reservoir portion that stores a moisturizing liquid provided facing the nozzle surface, and maintains the sealing property in the short direction of the liquid discharge head between the liquid reservoir portion and the liquid discharge head, and is long. A moisturizing cap that moisturizes the nozzle surface by having a sealing member that forms openings at both ends in the direction;
An airflow generating means for generating a flow of air supplied from one opening in the longitudinal direction of the liquid discharge head and discharged from the other opening;
A planar member provided on one side of the opening for supplying the air generated by the airflow generating means, facing the liquid reservoir;
Nozzle surface moisturizer.   The length of the planar member is adjusted so that the humidity distribution of the moisturizing space formed by the nozzle surface, the planar member, and the moisturizing cap is the moisture retaining humidity at the nozzle surface. Nozzle surface moisturizer.   The nozzle surface moisturizing device according to claim 1, wherein the planar member is provided in the liquid ejection head.   The nozzle surface moisture retention device according to claim 1 or 2, wherein the planar member is provided on the moisture retention cap.   The nozzle surface moisturizing device according to any one of claims 1 to 4, wherein a clearance between the nozzle surface and the moisturizing liquid is equal to a clearance between the planar member and the moisturizing liquid.   6. The nozzle surface moisturizing device according to claim 1, wherein the sealing member is an elastic member, and the elastic member abuts on the liquid ejection head. 7.   The said sealing member is a labyrinth structure which combines the 1st member provided in the said liquid discharge head, and the 2nd member provided in the said moisture retention cap, The any one of Claim 1 to 5 Nozzle surface moisturizer. A liquid discharge head having a nozzle surface on which a plurality of nozzles for discharging liquid are disposed;
Moving means for moving the liquid discharge head between an image forming position where the liquid discharge head discharges liquid to form an image on a medium and a standby position where the liquid discharge head does not form the image;
The nozzle surface moisturizing device according to any one of claims 1 to 7, provided at the standby position;
A liquid ejection apparatus comprising: A nozzle surface moisturizing method for moisturizing the nozzle surface of a liquid discharge head,
A liquid reservoir portion that stores a moisturizing liquid provided opposite to the nozzle surface, and maintains a short-side sealability of the head between the liquid reservoir portion and the liquid discharge head, and a longitudinal direction. A mounting step of mounting a moisture retaining cap having a sealing member that forms openings at both ends;
A blowing step of blowing air from one opening in the longitudinal direction of the liquid discharge head to the other opening, and
By having a flat member provided opposite to the liquid reservoir on the one opening side that supplies air blown by the blowing step, by adjusting the length of the flat member in the longitudinal direction, A nozzle surface moisturizing method that adjusts the humidity of the nozzle surface.   The nozzle surface moisturizing method according to claim 9, wherein the sealing member is an elastic member, and in the mounting step, the elastic member is brought into contact with the liquid ejection head.   The nozzle surface moisturizing method according to claim 9, wherein the mounting step combines a labyrinth structure including a first member provided on the liquid ejection head and a second member provided on the moisture retention cap.

Images