JP7218585B2 - Droplet ejection device - Google Patents

Description

The present invention relates to a droplet ejection device.

2. Description of the Related Art It is known that an inkjet printer is provided with an opening in the head, and humidified air is blown out from the opening to prevent drying of the ink in the ejection opening. For example, in the recording apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200001, humidified air is blown out from the blowing holes of the liquid discharge head during printing to prevent drying of the ink inside the discharge ports.

Japanese Unexamined Patent Publication No. 2016-165886

However, if the head is provided with an opening for humidified air, ink may enter the opening during maintenance of the head (during purging and wiping operations). This ink can dry and solidify, thereby blocking the flow of humidified air. A similar problem may also occur if the head has openings for airflow control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. It is an object of the present invention to provide a liquid droplet ejection device capable of preventing the occurrence of such a problem.

In order to achieve the above object, a droplet ejection device according to an aspect of the present invention is provided with a plurality of nozzles and a plurality of openings for ejecting or sucking gas for humidification or airflow control. In a purge operation during maintenance, the recording liquid is discharged from the plurality of nozzles while the gas is being ejected from the plurality of openings.

According to this configuration, the recording liquid can be prevented from entering the opening because the gas is ejected from the opening during the purge operation at the time of maintenance. There are various types of purging. In the case of a configuration in which the cap receives the discharged liquid, the cap is separated from the nozzle surface to receive the discharged liquid in the pressurization purge that pressurizes the print head from the upstream side. In a suction purge that applies a negative pressure to the nozzle surface, the cap abuts against the nozzle surface and receives the discharged liquid. Moreover, there is also a configuration in which the discharged liquid is received by a waste liquid receptacle other than the cap. According to the above configuration, it is possible to deal with any purge mode.

In a wiping operation after the purging operation, the nozzle surface may be wiped by a wiper while the gas is ejected from the opening.

According to this configuration, in the wiping operation, the recording liquid adhering to the nozzle surface due to purging is wiped off by the wiper. At this time, since the gas is ejected from the opening, it is possible to prevent the recording liquid from being pushed into the opening by the wiper.

The pressure of the gas ejected from the opening in the wiping operation may be higher than the pressure at which the gas is ejected from the opening in the purge operation.

The recording liquid is more likely to enter the opening during the wiping operation than during the purging operation. However, according to this configuration, in the wiping operation, the gas is ejected at a higher pressure than in the purging operation, so it is possible to appropriately prevent the recording liquid from being pushed into the opening.

In the nozzle surface of the recording head, the plurality of nozzles are arranged in a scanning direction to form a plurality of nozzle rows, and the plurality of nozzle rows are arranged in a carrying direction intersecting the scanning direction. Between and on both sides of the plurality of nozzle rows with respect to the transport direction, the openings are arranged along the nozzle rows to form a plurality of openings, and each of the plurality of openings extends along the nozzle rows. It may comprise a single elongated opening or a plurality of openings spaced apart from each other along the row of nozzles.

According to this configuration, since the openings are present along the nozzle rows, it is possible to appropriately perform humidification or airflow control on the target nozzles.

After the wiping operation, the humidifying gas may be ejected from the opening.

According to this configuration, since the inside of the cap is humidified after the wiping operation, drying of the meniscus of each nozzle can be prevented.

When the nozzle surface is covered with a cap, the humidifying gas is ejected from the opening on one side with respect to the center of the arrangement of the plurality of nozzle rows in the conveying direction, and the opening on the other side. The air inside the cap may be sucked from the portion.

According to this configuration, the inside of the cap can be humidified even during capping without breaking the meniscus of the nozzle.

The ejection of the humidifying gas and the suction of the air may be switched at predetermined time intervals.

According to this configuration, the meniscus of the nozzle can be uniformly humidified regardless of the location.

Advantageous Effects of Invention The present invention has the effect of providing a droplet discharge device capable of preventing recording liquid from entering openings for ejecting or sucking gas for humidification or airflow control of a recording head during maintenance.

FIG. 1 is a schematic diagram showing a schematic configuration of a droplet ejection device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the functional configuration of the droplet ejection device. FIG. 3 is a plan view showing an enlarged part of the print head, showing ejection channels. FIG. 4 is an enlarged cross-sectional view of a portion of the recording head, showing pressure chambers. FIG. 5 is a schematic diagram showing an overview of the arrangement of nozzle rows and openings on the nozzle surface of the print head. FIG. 6 is a schematic diagram showing an outline of the circulation paths of humidified air and suctioned air. FIG. 7 is a graph showing the flow of operation control of the opening during maintenance. FIG. 8A is a schematic diagram showing an overview of the purge operation in the comparative example. FIG. 8B is a schematic diagram showing an overview of the purge operation in the comparative example. FIG. 8C is a schematic diagram showing an overview of the purge operation in the comparative example. FIG. 9A is a schematic diagram showing an overview of the purge operation in the droplet discharge device of FIG. 1; FIG. 9B is a schematic diagram showing an overview of the purge operation in the droplet discharge device of FIG. 1; 10A is a schematic diagram showing an outline of a wiping operation in a comparative example; FIG. 10B is a schematic diagram showing an outline of a wiping operation in a comparative example; FIG. 10C is a schematic diagram showing an overview of the wiping operation in the comparative example. FIG. 11A is a schematic diagram showing an outline of a wiping operation in the droplet ejection device of FIG. 1; FIG. 11B is a schematic diagram showing an outline of a wiping operation in the droplet discharge device of FIG. 1; FIG. 11C is a schematic diagram showing an outline of a wiping operation in the droplet discharge device of FIG. 1; FIG. 12A is a schematic diagram showing an overview of the wiping end operation in the droplet discharge device of FIG. 1; 12B is a schematic diagram showing an overview of the wiping end operation in the droplet discharge device of FIG. 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the same or corresponding elements throughout all the drawings, and duplicate descriptions thereof will be omitted. It should be noted that the following drawings are for explaining the present invention, so if elements unrelated to the present invention are omitted, if dimensions are not accurate due to exaggeration or the like, corresponding elements in multiple drawings may be omitted. There are cases where the forms do not match. Moreover, the present invention is not limited to the following embodiments.

(embodiment)
An ink ejection device that ejects ink onto a recording sheet will be described below as an example of a liquid droplet ejection device according to an embodiment of the present invention. However, the liquid ejected by the droplet ejection device according to the present invention is not limited to ink, and the object to which the ejected liquid adheres is not limited to a sheet-like object. Further, the droplet ejection device is not limited to an ink ejection device, and may be any device that ejects recording liquid onto a recording medium.

[Configuration of Droplet Ejecting Device]
FIG. 1 is a schematic diagram of a droplet discharge device 1. FIG. Regarding the droplet ejection device 1, the direction in which the carriage 12 reciprocates is called the horizontal direction (corresponding to the scanning direction), and the direction in which the recording sheet P is conveyed over the platen 11 is called the conveying direction. The conveying direction may be any direction that intersects the left-right direction, and here, it is the direction perpendicular to the left-right direction. In FIG. 1, the direction orthogonal to the paper surface is the horizontal direction, and the direction from left to right is the conveying direction. Furthermore, the vertical direction indicates the vertical direction of the droplet discharge device 1 .

Referring to FIG. 1, the droplet ejection device 1 is assembled with a paper feed tray 10, a platen 11 and a carriage 12 in order from the bottom. The paper feed tray 10 accommodates a plurality of recording sheets (recording paper) P. As shown in FIG. A horizontally long platen 11 is provided above the paper feed tray 10 . The platen 11 is a flat plate member and supports the conveyed recording sheet P from below. A carriage 12 is provided further above the platen 11 . A recording head 13 and the like are mounted on the carriage 12 . A discharge tray 14 is provided on the downstream side of the platen 11 in the conveying direction, and receives the recording sheet P for which recording has been completed.

A path from the paper feed tray 10 to the paper discharge tray 14 is a sheet transport path 20 . The sheet conveying path 20 can be divided into three paths, a curved path 21, a straight path 22, and an end path 23, from upstream. In the straight path 22, the recording sheet P is placed on the platen 11 and faces the recording head 13 with a predetermined gap therebetween. Droplets 101 are ejected from the recording head 13 and an image is formed on the recording sheet P. FIG.

The droplet ejection device 1 includes a feed roller 30, a transport roller 31, and a discharge roller 34 as a sheet transport mechanism for transporting the recording sheet P. As shown in FIG. Specifically, the feed roller 30 is provided directly above the paper feed tray 10 . The conveying roller 31 forms a conveying roller portion 33 together with the pinch roller 32 and connects the curved path 21 and the straight path 22 . The discharge roller 34 constitutes a discharge roller portion 36 together with a spur roller 35 and connects the straight path 22 and the end path 23 .

Here, when the sheet conveying mechanism is driven, the recording sheet P is fed out from the sheet feeding tray 10 to the curved path 21 by the feeding roller 30 . The recording sheet P is placed on the platen 11 by the conveying roller unit 33 and an image is recorded by the recording head 13 . The recorded recording sheet P is discharged to the paper discharge tray 14 by the discharge roller unit 36 .

The liquid ejection device 1 includes a carriage 12 , a guide member (not shown), and an endless belt (not shown) as a head scanning mechanism that reciprocates the liquid ejection head 13 . The head scanning mechanism reciprocates the carriage 12 across the sheet conveying path 20 .

Among these, the guide members are two parallel support bars. The support bar is arranged to extend in the left-right direction, and the carriage 12 is slidably attached to it. The endless belt is arranged parallel to the support bar and the carriage 12 is fixed. When a carriage motor 51 (FIG. 2), which will be described later, rotates, the endless belt runs and the carriage 12 moves along the support rod.

One end of the moving path of the carriage 12 is a maintenance port. The maintenance port is provided with a cap 101, a wiping member 110, a pump 55, and the like to constitute a maintenance mechanism. Pump 55 is connected to cap 101 . During maintenance (flushing or purging) of the recording head 13 , the cap 101 contacts the nozzle surface 13 b of the recording head 13 . The controller 40 drives the pump 55 by controlling the pump driver IC 54 . At this time, the inside of the cap 101 is sucked by the pump 55 and the ink is discharged from the recording head 13 . After that, the nozzle surface 13 b is released from the cap 101 and wiped by the wiping member 110 .

FIG. 2 is a block diagram showing the functional configuration of the droplet discharge device 1. As shown in FIG. The control unit 40 of the droplet ejection device 1 includes a first substrate and a second substrate. A CPU 41, a ROM 42, a RAM 43, and an EEPROM 44 are mounted on the first board, and an ASIC 45 is mounted on the second board. Two motor driver ICs 46 and 47, a head driver IC 48, and two pump driver ICs 52 and 54 are connected to the ASIC 45. FIG. A motor driver IC 46 drives a conveying motor 50 . A motor driver IC 47 drives a carriage motor 51 . A head driver IC 48 drives a piezoelectric element 71 (described later) of the recording head 13 . The piezoelectric element 71 constitutes an actuator that ejects ink. The pump driver IC 52 drives a pump 53 for airflow control. The pump driver IC 54 drives a cap suction pump 55 .

When the droplet discharge device 1 receives a print command from a user or another communication device, the CPU 41 (control unit 40) outputs various execution commands to the ASIC 45 based on the programs stored in the ROM 42. FIG. The ASIC 45 controls each driver IC 46-48 based on this command. As a result, recording processing and maintenance processing are executed.

Specifically, the motor driver IC 46 drives the conveying motor 50 to rotate the three rollers 30 , 31 , 34 . The motor driver IC 47 drives the carriage motor 51 to run the endless belt. The head driver IC 48 drives the piezoelectric element to vibrate the meniscus and eject ink.

The droplet ejection device 1 also includes various sensors (eg, a leading edge detection sensor for detecting the position of the recording sheet P, an encoder for detecting the position of the carriage, etc.). The control unit 40 controls each driver IC 46-48 based on signals from these sensors.

In addition to the pump driver IC 52 , a pump driver IC 54 for driving the pump 55 is connected to the ASIC 45 . The control unit 40 controls these two pump driver ICs 52 and 54 to perform maintenance operations (including airflow control operations). This maintenance operation will be described later in detail.

[Structure of recording head]
FIG. 3 is a schematic diagram showing a partially enlarged flow path of the recording head 13. As shown in FIG. The recording head 13 has an ink channel and a gas channel (not shown) formed therein. The ink flow path includes a manifold 60 and a plurality of ejection channels 70 . The discharge channel 70 is a separate flow path, leading from the outlet 72 a of the manifold 60 through the pressure chamber 73 to the nozzle 75 .

The nozzles 75 constitute a nozzle row 81 (see FIG. 5) as described later. Although not shown in FIG. 3, openings 82 (see FIG. 5) are formed along the nozzle row 81. As shown in FIG. These nozzle rows 81 and openings 82 will be described later in detail.

FIG. 4 is a cross-sectional view of discharge channel 70 taken along line IV--IV shown in FIG. Referring to FIG. 4, the actuator constitutes pressure chamber 73 . The actuator is a laminate of a piezoelectric element 71 and a vibration plate 71a, and the former is driven to expand and contract in the planar direction (direction perpendicular to the vertical direction). On the other hand, diaphragm 71a does not deform spontaneously. Therefore, the actuator deforms toward the pressure chamber 73 upon application of the drive voltage. At this time, ink is ejected from the nozzles 75 .

The lower surface of the recording head 13 is the nozzle surface 13b, on which many nozzles 75 are open. An opening 82 (see FIG. 5) is also opened in the nozzle surface 13b. From this opening 82, gas for humidification or airflow control is jetted (jetted) or air is sucked into the space near the nozzle surface 13b (hereinafter referred to as the recording space). The opening 82 is connected to the pump 53 via a gas flow path.

[Arrangement of Nozzle Rows and Openings]
FIG. 5 is a schematic diagram showing the arrangement form of the nozzle rows 81 and the openings 82 on the nozzle surface 13b.

On the nozzle surface 13b, a plurality of nozzles 75 (see FIG. 4) are aligned in the transport direction to form a nozzle row 81, and a plurality of (here, two) nozzle rows 81 are aligned in the horizontal direction. Note that when the recording head 13 is of a line head type, the plurality of nozzles 75 are arranged in the horizontal direction.

An opening 82 is formed along the nozzle row 81 . Aperture 82 includes an elongated aperture or an array of apertures. According to this configuration, since the nozzle rows 81 and the openings are adjacent to each other, the openings 82 can appropriately humidify or control the airflow with respect to the target nozzles 75 . Here, the opening 82 consists of one elongated opening.

The openings 82 are arranged upstream, between, and downstream of the plurality of nozzle rows 81 in the left-right direction. At this time, the opening 82 should be located at a position where humidification and airflow control can effectively reach the nozzle row 81 . For example, in this embodiment, the liquid ejection device 1 is a unidirectional printer. Therefore, as shown in FIG. 8, the openings 82 are arranged closer to the downstream side (forward in the movement direction) of the nozzle row 81 with respect to the movement direction of the recording head 13 during image formation.

In addition, in FIG. 8, the openings 82 and the nozzle rows 81 form one-to-one pairs, and three pairs are shown. Furthermore, the opening 82 may be on the most upstream side of the nozzle row 81 .

Here, the gas for humidification or airflow control is preferably inert to the ink. Examples of such gas include humidified air and nitrogen gas. In the following, a case where the gas for humidification or airflow control is humidified air will be exemplified.

[Circulation Path of Humidified Air and Suction Air]
FIG. 6 is a schematic diagram of flow paths of humidified air and sucked air. The air communication path includes a supply/discharge opening 91, a humidified air tank 92, a three-way valve 93, a pump 53, an opening 82, and the like. These elements are arranged as shown in FIG. 6 and constitute a humidified air supply path 90A and an air suction path 90B.
Of these, the humidified air supply path 90A extends from the supply/discharge opening 91 to the opening 82 via the humidified air tank 92, the three-way valve 93, and the pump 53. Humidified air flows along this array. On the other hand, the air suction path 90B extends from the opening 82 to the supply/discharge opening 91 via the pump 53 and the three-way valve 93 . Suction air flows along this array. At this time, the humidified air tank 92 is bypassed by the three-way valve 93 .

The humidified air supply path 90A and the air suction path 90B are provided at least for each one or a plurality of openings 82. However, if the openings 82 are composed of a plurality of openings, they may be provided for each opening. good.

The supply/discharge opening 91 is provided, for example, in the periphery of the nozzle surface 13b, avoiding the set of the nozzle 75 and the opening 82. As shown in FIG. Here, the supply/discharge opening 91 is one opening 82 and is located on the most upstream side of the nozzle row 81 . When the humidified air is supplied to the opening 82 , humidifying air is sucked through the supply/discharge opening 91 . When air is sucked from the opening 82 , this air is discharged from the supply/discharge opening 91 .

A humidified air tank 92 is provided at an appropriate location of the droplet ejection device 1 . The humidified air tank 92 stores water. The air from the supply/discharge opening 91 is supplied below the surface of the water and is humidified while rising in the water. As a result, the upper space of the humidified air tank 92 is filled with humidified air.

The three-way valve 93 connects one connection port of the pump 53 to either the humidified air tank 92 or the bypass path of the humidified air tank 92 . When humidified air is supplied to the opening 82 , the three-way valve 93 connects the pump 53 and the humidified air tank 92 . When air is sucked from the opening 82, the three-way valve 93 connects the pump 53 and the bypass route. Operation of the three-way valve 93 is controlled by a valve driver IC (not shown) connected to the ASIC 45 .

The pump 53 rotates forward to create an airflow toward the opening 82 (injection operation). At this time, humidified air is jetted from the opening 82 . Also, the pump 53 rotates in the reverse direction to create an air flow toward the supply/discharge opening 91 (suction operation). At this time, the air in the recording space is sucked through the opening 82 . The operation of pump 53 is controlled by pump driver IC 52 connected to ASIC 45 .

In the above configuration, the three-way valve 93 connects the pump 53 to the humidified air tank 92 when humidified air is supplied to the opening 82 . When the pump 53 is driven in this state, the air taken into the supply/discharge opening 91 is humidified in the humidified air tank 92 and jetted as humidified air from the opening 82 into the recording space.

Also, when air is sucked from the opening 82 , the three-way valve 93 connects the pump 53 to the bypass path of the humidified air tank 92 . When the pump 53 is driven in this state, the air in the recording space is sucked through the opening 82 and discharged through the supply/discharge opening 91 . The ejection speed of humidified air and the suction speed of air in the recording space are roughly proportional to the ejection pressure and suction pressure of the pump 53, respectively.

[motion]
Next, the maintenance operation of the droplet ejection device 1 will be described. This maintenance operation is a purge followed by a wipe. In purging, the recording head 13 is sucked and the ink is forcibly discharged. The wipe wipes the nozzle surface 13b. At this time, the control unit 40 controls the airflow in the recording space in accordance with the progress of the maintenance operation.

In the maintenance operation, the controller 40 controls multiple driver ICs. In the purge, the controller 40 drives the pumps 53 and 55, switches the three-way valve, drives the maintenance mechanism (for example, moves the cap 101), and the like. In wiping, the control unit 40 drives the pump 53, drives the maintenance mechanism (for example, moves the wiping member 110), and the like. The control of the plurality of driver ICs is performed by the control unit 40 according to the control program stored in the ROM 42 as described above.

FIG. 7 shows a timetable of airflow control during maintenance. The horizontal axis indicates time. The vertical axis indicates the injection pressure of the humidified air, and the negative area corresponds to the suction pressure of the air.

Referring to FIGS. 5 and 7, in this embodiment, the maintenance operation is composed of a purge preparation operation OM1, a purge operation OM2, a wiping operation OM3, and a wiping end operation OM4, which are continuous with each other.

<Purge preparation operation OM1>
When the maintenance operation is started, first, the purge preparation operation OM1 is performed. Injection of humidified air and capping of the nozzle surface 13b (sealing with the cap 101) start. The control unit 40 drives the carriage motor 51 to cause the nozzle surface 13b to face the cap 101 . Furthermore, the controller 40 drives the maintenance mechanism to lift the cap 101 (see FIG. 8A). During this time, the controller 40 switches the three-way valve 93 and drives the pump 53 to supply humidified air to all the openings 82 . At this time, the injection pressure of the humidified air starts from zero and rises to the first pressure P1. This completes preparations for preventing ink from entering the openings 82 .

<Purge operation OM2>
A purge operation OM2 is then performed. 8A to 8C are schematic diagrams showing a purge operation as a comparative example. 9A and 9B are schematic diagrams showing an overview of the purge operation OM2 of this embodiment. Although three sets of nozzle rows 81 and openings 82 are shown in FIGS. 8A to 9B, this is an example, and there may be four or more sets. This also applies to FIGS. 10A-11C.

The comparative example is a configuration example in which there is no injection from the opening 82 in the purge operation. In this case, the controller 40 performs capping and suction inside the cap 101 .

In the comparative example, when the suction purge is performed, the ink 102 is discharged from the nozzle 75 and begins to accumulate in the cap 101 as shown in FIG. 8A. Bubbles are mixed in the ejected ink 102 . Furthermore, the ejected ink 102 touches the nozzle surface 13b. Therefore, a meniscus is formed in the opening 82 (see FIG. 8C), and the ink 102 begins to enter the inside.

The ink 102a (see FIG. 8C) adhering to the vicinity of the opening 82 repeatedly dries and accumulates, causing narrowing and sealing of the opening 82 . Therefore, in an image forming operation, for example, humidified air cannot be jetted from the opening 82 .

On the other hand, in the droplet ejection device 1 of the present embodiment, as shown in FIGS. 7 and 9A, the purge operation OM2 is performed along with ejection from the opening 82. FIG. At this time, the controller 40 switches the three-way valve 93 to allow the humidification tank 92 and the pump 53 to communicate with each other. Furthermore, the control unit 40 drives the pump 53 . As a result, humidified air at the first pressure P<b>1 is jetted from all the openings 82 . When the suction purge is performed in this state, as shown in FIG. 9A, even if the ink 102 adheres to the vicinity of the opening 82, it will not form a meniscus or enter the inside of the opening.

When the suction purge ends, the cap 101 is lowered and the purge operation OM2 ends (see FIG. 9B). At this time, the controller 40 drives the maintenance mechanism to move the cap 101 .

<Wiping operation OM3>
A wiping operation OM3 is then performed. At this time, the control unit 40 drives the maintenance mechanism to move the wiping member 110 . 10A to 10C are schematic diagrams showing a wiping operation as a comparative example. Humidified air is not jetted from the openings 82 . 11A to 11C are schematic diagrams showing the wiping operation OM3 of this embodiment. Humidified air is jetted from the opening 82 .

After the purge operation OM2, the nozzle surface 13b is adhered with a mass of ink 103 (see FIG. 10A).

In this state, when the wiping member 110 wipes the nozzle surface 13 b , the lumps of ink 103 are collected and reach the opening 82 . Some of the ink 103 forms a meniscus at the opening or is pushed into the opening (see Figure 10B).

The ink 103 (see FIG. 10C) remaining in the opening 82 repeatedly dries and accumulates, causing narrowing and sealing of the opening 82 . Therefore, in an image forming operation, for example, humidified air cannot be jetted from the opening 82 .

On the other hand, in the droplet discharge device 1 of the present embodiment, as shown in FIGS. 7 and 11A, humidified air is jetted from all the openings 82 at the second pressure P2. At this time, the controller 40 continues driving the pump 53 from the purge. And the second pressure P2 is higher than the first pressure P1.

In this state, when the wiping member 110 starts wiping the nozzle surface 13b, the ink 103 is pushed back by the moist air at the openings 82 as shown in FIG. 11B. Even if the ink 103 adheres to the vicinity of the opening 82 , it will not form a meniscus or enter the opening 82 .

Note that the ink 103 is collected by the wiping member 110 and passes over the opening 82 . Therefore, the ink 103 is more likely to enter the opening 82 during the wiping operation OM3 than during the purge operation OM2. However, in this embodiment, the injection pressure of the humidified air is higher during the wiping operation OM3 than during the purge operation OM2. Therefore, it is possible to appropriately prevent the lumpy ink 103 from being pushed into the opening 82 .

When the wiping member 110 finishes wiping the nozzle surface 13b, the wiping operation OM3 ends (see FIG. 11C). A fresh meniscus is formed at the nozzle 75 by the wiping action. If a print command is input, the recording head 13 is scanned and image formation begins. If no print command is input, the control unit 40 performs capping and puts the recording head 13 in a standby state.

<Wiping end operation OM4>
12A and 12B are schematic diagrams showing the wiping end operation OM4. In the wiping end operation OM4, all nozzle rows 81 and openings 82 are capped. Here, in addition to the three sets of nozzles 75 and openings 82, an opening 82 as a supply/discharge opening 91 is shown at the upstream end in the scanning direction during image formation.

Referring to FIG. 12A, when the wiping operation OM3 ends, the wiping end operation OM4 is started. In this wiping end operation OM4, the cap 101 is raised to a predetermined position as in the purge operation OM2. Humidified air is jetted from the opening 82 in this state. As a result, the inside of the cap 101 is humidified after the wiping operation OM3, so that the meniscus of each nozzle 75 can be prevented from drying.

Specifically, humidified air is jetted from the opening 82 at the downstream end in the scanning direction. The air inside the cap 101 is sucked from the opening 82 (the supply/discharge opening 91) at the upstream end in the scanning direction. The air intake/exhaust operation is stopped at the opening 82 in the middle portion in the scanning direction. At this time, as shown in FIG. 7, the injection pressure of the humidified air is lower than the injection pressure in the wiping operation OM3. The absolute value of the air suction pressure (negative pressure) is the same as the injection pressure.

As a result, a flow of humidified air is formed in the cap 101 from the opening 82 at the downstream end in the scanning direction toward the opening 82 at the upstream end in the scanning direction. According to this configuration, all the nozzles 75 can be humidified without destroying the meniscus of the nozzles 75 . Then, after a predetermined period of time has passed, the state of air intake/exhaust at the opening 82 is switched as shown in FIG. 12B. As a result, a flow of humidified air is formed in the cap 101 from the opening 82 at the upstream end in the scanning direction toward the opening 82 at the downstream end in the scanning direction.

In this manner, the direction of the flow of humidified air in the cap 101 is switched every predetermined time. As a result, the meniscus of the nozzle 75 can be uniformly humidified regardless of the location.

The wiping end operation OM4 ends when the next image forming operation starts. When the wiping end operation OM4 ends, the maintenance operation ends.

In the image forming operation, for example, humidified air is jetted from the opening 82 to prevent drying of the meniscus. Also, an airflow control gas is jetted from the opening 82 to control the airflow in the recording space, thereby suppressing the generation of eddy currents. This suppresses the disturbance of the landing positions of the droplets. For details of these controls, see, for example, Japanese Unexamined Patent Application Publication No. 2016-165886.

According to the present embodiment, ink is prevented from entering the openings 82 during maintenance operations, so that the openings 82 operate without being hindered by the ink entering during image forming operations, and the meniscuses of the nozzles 75 are removed. It is possible to suitably prevent drying of the liquid droplets and disturb the landing positions of the liquid droplets ejected from the nozzles 75 .

(Other embodiments)
In the above-described embodiment, the suction purge is performed in the purge operation OM2, but the pressure purge that pressurizes the print head 13 from the upstream side may be performed. In this case, the cap 101 is arranged away from the nozzle face 13b and configured to receive the ink discharge. Alternatively, a waste liquid receiver other than the cap 101 may be provided to receive the discharged ink. In any purge mode, the ink is discharged from the nozzles 75 in a state in which the gas for humidification or airflow control is jetted from the openings 82, so that the ink can be prevented from entering the openings 82. .

Many modifications and other embodiments will be apparent to those skilled in the art from the above description. Accordingly, the above description should be construed as illustrative only.

INDUSTRIAL APPLICABILITY The droplet ejection device of the present invention is useful as a droplet ejection device capable of preventing recording liquid from entering openings for ejecting or sucking gas for humidifying or controlling airflow of a recording head during maintenance.

1 droplet ejection device 12 carriage 13 recording head 13b nozzle surface 40 control unit 42 ROM
45 ASICs
52 pump driver IC
53 Pump 75 Nozzle 81 Nozzle row 82 Opening 90A Humidified air supply path 90B Air suction path 91 Supply/discharge opening 92 Humidified air tank 93 Three-way valve 101 Cap 102 Ink 102a Ink 103 Mass ink 110 Wiping member OM1 Purge preparation operation OM2 Purge operation OM3 Wiping operation OM4 Wiping end operation P1 First pressure P2 Second pressure

Claims (7)

A recording head having a nozzle surface provided with a plurality of nozzles and a plurality of openings for ejecting or sucking gas for humidification or airflow control,
1. A liquid droplet ejecting apparatus configured to eject recording liquid from said plurality of nozzles while said gas is being ejected from said plurality of openings in a purge operation during maintenance. 2. The liquid droplet ejecting apparatus according to claim 1, wherein in a wiping operation after said purge operation, said nozzle surface is wiped by a wiper while said gas is ejected from said opening. 3. The droplet ejection device according to claim 2 , wherein the pressure of the gas ejected from the opening in the wiping operation is higher than the pressure of the gas ejected from the opening in the purge operation. The recording head is
On the nozzle surface, the plurality of nozzles are aligned in the scanning direction to form a plurality of nozzle rows, the plurality of nozzle rows are arranged in a transport direction intersecting the scanning direction, and the plurality of nozzle rows are aligned in the transport direction. Between and on both sides of the nozzle rows, the openings are arranged along the nozzle rows to form a plurality of openings,
4. According to claim 2 or 3, each of the plurality of openings includes one elongated opening extending along the nozzle row or a plurality of openings spaced apart from each other along the nozzle row. Droplet ejection device as described. 5. The liquid droplet ejecting apparatus according to claim 4, wherein said humidifying gas is ejected from said opening after said wiping operation. when the nozzle surface is covered with a cap,
In the conveying direction, with respect to the center of the arrangement of the plurality of nozzle rows, the humidifying gas is ejected from the opening on one side, and the air in the cap is sucked from the opening on the other side. 6. The liquid droplet ejecting device according to claim 4, which is configured as 7. The liquid droplet ejecting apparatus according to claim 6, wherein jetting of the humidifying gas and sucking of the air are switched at predetermined time intervals.

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