JP6915707B2 - Liquid injection device - Google Patents

Description

The present invention relates to a liquid injection device such as a printer.

In an inkjet printer, which is an example of a liquid injection device, a cleaning agent is ejected into a mist to a nozzle that ejects ink to dissolve solid components of ink that are stuck around the nozzle or near the opening. After that, there is a method in which the dissolved substance is blown off by discharging a gas to remove it (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-178529

By the way, when the nozzle is clogged, the clogging of the nozzle can be cleared by vigorously introducing the droplets of the cleaning agent into the nozzle. However, if droplets of cleaning liquid enter the unclogging nozzle, the meniscus (curved liquid surface) formed in the nozzle may be broken, and the injection performance of the nozzle may be deteriorated. As described above, when the liquid injection portion having the nozzle is maintained by the droplets, the maintenance result changes depending on the state of the nozzle, so that there is a problem that the maintenance efficiency is poor.

It should be noted that such a problem is generally common not only in a printer that injects ink to print, but also in a liquid injection device having a nozzle for injecting a liquid.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid injection device capable of efficiently performing maintenance of a liquid injection unit having a nozzle capable of injecting a liquid.

Hereinafter, means for solving the above problems will be described.
A liquid injection device that solves the above problems includes a liquid injection unit having a nozzle capable of injecting a first liquid into a medium, and a gas and a second liquid with respect to the liquid injection surface of the liquid injection unit through which the nozzle opens. A fluid injection device having a fluid injection nozzle capable of injecting a mixed fluid with the liquid injection device, the fluid injection device supports the fluid injection nozzle so as to be reciprocally movable along the liquid injection surface of the liquid injection unit. As a maintenance operation for maintaining the liquid injection portion, the support portion has a support portion and a support portion moving mechanism for reciprocating the support portion along the liquid injection surface, and the liquid injection surface is mixed with the liquid injection surface. Liquid injection is performed.
A liquid injection device that solves the above problems can inject a liquid containing a second liquid into a liquid injection unit having a nozzle capable of injecting a first liquid into a medium and a liquid injection surface opened by the nozzle. A guide unit including a fluid injection device having a fluid injection nozzle provided with an injection port, and the fluid injection device guides the fluid injection nozzle so as to reciprocate along the liquid injection surface of the liquid injection unit. As a maintenance operation for maintaining the liquid injection unit, a fluid injection that injects a fluid containing the second liquid is performed on the liquid injection surface opened by the nozzle of the liquid injection unit, and the fluid is injected. The distance between the injection port and the liquid injection surface in the injection is longer than the distance between the liquid injection surface and the medium when the liquid injection unit injects the first liquid onto the medium in the direction of gravity. ..
The liquid injection device that solves the above problems has a liquid injection unit having a nozzle capable of injecting the first liquid into the medium, and an injection port capable of injecting a fluid containing the second liquid into the liquid injection unit. The fluid injection device includes a fluid injection device, and the fluid injection device is smaller than the opening of the nozzle with respect to the opening region of the liquid injection unit where the nozzle opens as a maintenance operation for performing maintenance of the liquid injection unit. A first fluid injection for injecting a fluid containing small droplets of the second liquid and a fluid containing the droplets of the second liquid having a smaller minimum droplet than the small droplets are injected to the liquid injection unit. The second fluid injection is performed.

According to this configuration, the fluid injection device injects the first fluid into the opening region to introduce small droplets of the second liquid smaller than the opening of the nozzle into the nozzle, thereby clogging the nozzle. Maintenance can be performed to eliminate it. On the other hand, in the second fluid injection performed by the fluid injection device on the liquid injection unit, since the droplet of the second liquid whose minimum droplet is larger than the small droplet is ejected, it is difficult for the droplet to enter the nozzle. Therefore, it is possible to prevent the meniscus formed in the nozzle from being destroyed by the droplet of the second liquid entering the nozzle that is not clogged. Therefore, maintenance of the liquid injection unit having the nozzle capable of injecting the liquid can be efficiently performed.

The liquid injection device includes a wiping member capable of wiping the liquid injection portion, and as the maintenance operation, after the fluid injection device injects the second fluid into the opening region, the wiping member performs the wiping member. Wipe the opening area.

According to this configuration, the fluid injection device injects the second fluid into the opening region to clean the opening region while suppressing the droplets of the second liquid from destroying the meniscus in the nozzle. be able to. Further, since the fluid injection device injects the second fluid into the opening region, the second liquid adheres to the opening region of the liquid injection portion, and then the wiping member wipes the opening region to obtain the liquid. Maintenance of the opening region is performed in a state where the wiping member is moistened by the second liquid adhering to the injection portion. As a result, the frictional resistance becomes smaller than when the wiping member wipes the opening region in a dry state, so that the load applied to the opening region by the wiping operation can be reduced. Further, by moistening the fixed substance stuck to the opening region with the second liquid, the fixed substance is dissolved in the second liquid, so that the foreign matter stuck to the opening region can be efficiently removed by wiping with the wiping member. ..

The liquid injection device includes a wiping member capable of wiping the liquid injection unit, and when a region of the liquid injection unit that does not include the opening region is a non-opening region, the fluid injection device performs the maintenance operation. After the second fluid injection is performed on the non-opening region to attach the second liquid to the liquid injection portion, the wiping member comes into contact with the non-opening region, and the wiping member further contacts the non-opening region. Wipe off.

According to this configuration, the fluid injection device performs the second fluid injection on the non-open area to clean the non-open area while suppressing the droplets of the second liquid from destroying the meniscus in the nozzle. It can be performed. Further, the wiping member can be wetted with the second liquid by contacting the wiping member with the non-opening region after the second fluid injection. Therefore, by wiping the opening region after that, the foreign matter adhering to the opening region can be removed while reducing the load applied to the opening region as compared with the case where the wiping member wipes the opening region in a dry state. ..

In the liquid injection device, the second liquid is pure water or a liquid containing a preservative in pure water.
According to this configuration, by using pure water as the main component of the second liquid, even if the second liquid enters the nozzle, the deterioration due to mixing with the second liquid of the first liquid in the nozzle is prevented. It can be suppressed. Further, when the pure water which is the main component contains a preservative, it is possible to suppress the putrefaction of the second liquid held in the fluid injection device.

In the liquid injection device, the fluid injection device can inject a fluid containing a third liquid containing a liquid repellent component, and as the maintenance operation, the fluid injection device makes the small liquid with respect to the liquid injection unit. A fluid containing a droplet of the third liquid having a smaller minimum droplet than the droplet is ejected.

According to this configuration, the fluid injection device injects a fluid containing a third liquid containing a liquid repellent component to adhere the third liquid to the liquid injection portion and improve the liquid repellent property of the liquid injection portion. be able to. Then, by improving the liquid repellency of the liquid injection unit, the liquid injection unit injects the first liquid from the nozzle toward the medium, so that a minute mist of the first liquid is unintentionally generated, and the mist is generated. Can prevent the first liquid from sticking to the liquid injection part even when the liquid is attached to the liquid injection part.

In the liquid injection device, in the injection direction in which the fluid injection device injects fluid from the injection port, the distance from the injection port to the liquid injection portion is larger than that when the first fluid injection is performed. It is longer when performing fluid injection.

According to this configuration, the distance from the injection port to the liquid injection portion when the fluid injection device performs the second fluid injection is longer than that when the first fluid injection is performed, so that the liquid injection portion is subjected to the second fluid injection. The flying speed of the arriving second liquid droplet becomes relatively slow. This makes it difficult for the second liquid to enter the nozzle, and even if it does, the impact when it collides with the meniscus is reduced, so that the destruction of the meniscus can be suppressed. In addition, if the flying speed of the droplets is high, there is a risk that the droplets will vigorously collide with the liquid injection part and scatter to the surroundings. It is possible to suppress scattering and efficiently attach the second liquid to the liquid injection portion.

In the liquid injection device, the direction in which the fluid injection device injects fluid from the injection port in the first fluid injection is set as the first injection direction, and the fluid injection device injects fluid from the injection port in the second fluid injection. Assuming that the injection direction is the second injection direction, the intersection angle of the second injection direction with respect to the opening surface at which the nozzle opens in the liquid injection portion is smaller than the intersection angle of the first injection direction with respect to the opening surface.

According to this configuration, the intersection angle of the second injection direction with respect to the opening surface where the nozzle opens is smaller than the intersection angle of the first injection direction with respect to the opening surface, so that the liquid of the second liquid injected by the second fluid injection Drops do not easily enter the nozzle. Therefore, it is possible to suppress the destruction of the meniscus of the nozzle due to the second fluid injection.

In the liquid injection device, the fluid injection device can selectively inject three types of a gas, the second liquid or a mixed fluid of the gas and the second liquid from the injection port, and the fluid injection device is the said. Assuming that the direction in which the gas is injected from the injection port is the gas injection direction, the angle θ of the gas injection direction with respect to the opening surface at which the nozzle opens in the liquid injection portion is 0 ° ≦ θ <90 °.

According to this configuration, the angle of the gas injection direction with respect to the opening surface where the nozzle opens is 0 ° ≤ θ <90 °, so that the gas injected from the injection port does not enter the nozzle and disturb the meniscus. NS. In addition, the fluid injection device injects the gas into the liquid injection part with the intersection angle with respect to the opening surface reduced, so that the gas flows along the opening surface and the deposits adhering to the liquid injection part are blown off for efficiency. Can be removed well.

In the liquid injection device, the product of the mass of the small droplets ejected by the fluid injection device from the injection port toward the nozzle and the square of the flight speed of the small droplets at the opening position of the nozzle is It is larger than the product of the mass of the droplet of the first liquid ejected from the nozzle by the liquid injection unit and the square of the flight speed of the droplet.

The kinetic energy of the ejected droplet is determined by the product of the mass of the droplet and the square of the flight speed of the droplet at a predetermined position, and the kinetic energy of the first liquid droplet ejected from the nozzle by the liquid injection unit is obtained. If the kinetic energy is large, even if the nozzle is slightly clogged, the clogging can be cleared by the energy of the droplet. On the other hand, when the nozzle is severely clogged, the clogging cannot be cleared by the energy for ejecting the first liquid droplet from the nozzle. In that respect, according to the above configuration, the kinetic energy at the nozzle opening position of the small droplet ejected from the injection port toward the nozzle by the fluid injection device is larger than the energy for ejecting the first liquid droplet from the nozzle. .. Therefore, the clogging of the nozzle, which cannot be cleared by the injection operation of ejecting the first liquid droplets from the nozzle opening, is eliminated by the kinetic energy when the second liquid droplets ejected by the fluid injection device enter the nozzle. can do.

In the liquid injection device, the liquid injection unit has a pressure generating chamber communicating with the nozzle and an actuator capable of pressurizing the pressure generating chamber, and the pressure is generated by driving the actuator in the liquid injection unit. In a state where the first liquid in the room is pressurized, the fluid injection device injects the first fluid into the opening region of the liquid injection portion.

According to this configuration, when the fluid injection device injects the first fluid into the opening region of the liquid injection portion, the actuator is driven in the liquid injection portion to pressurize the pressure generating chamber communicating with the nozzle. , The pressure in the nozzle increases, and it becomes difficult for the small droplets of the second liquid ejected by the fluid injection device to enter the inner back side of the nozzle. Therefore, when a film is stretched on the opening of the nozzle in the liquid injection section, a small droplet of the second liquid ejected by the fluid injection device collides with the film stretched on the opening of the nozzle to destroy the film. Foreign matter such as the broken film is suppressed from entering the nozzle. Therefore, even when the droplets are ejected from the outside of the nozzle to eliminate the clogging, it is possible to suppress the mixing of the droplets and foreign matter into the nozzle.

The schematic diagram which shows one Embodiment of the liquid injection apparatus. The plan view which shows typically the arrangement of the component of a liquid injection device. Bottom view of the head unit. An exploded perspective view of the head unit. FIG. 3 is a cross-sectional view taken along the line AA'in FIG. An exploded perspective view of the liquid injection part. Top view of the liquid injection part. (A) is a cross-sectional view taken along the line BB'in FIG. 7, (b) is an enlarged view in the right alternate long and short dash line frame in (a), and (c) is in the left alternate long and short dash line frame in (a). Enlarged view. The plan view which shows the structure of the maintenance apparatus. The schematic diagram which shows the structure of the fluid injection apparatus of 1st Embodiment. The perspective view of the injection unit of 1st Embodiment. FIG. 6 is a schematic side sectional view showing a usage state of the injection unit of the first embodiment. The block diagram which shows the electrical structure of the liquid injection device. FIG. 6 is a schematic side sectional view showing a usage state of the injection unit of the first embodiment. FIG. 6 is a schematic side sectional view showing a standby state of the injection unit of the first embodiment. The schematic diagram which shows the structure of the fluid injection apparatus of 2nd Embodiment. The table which shows the operation mode of the fluid injection apparatus of 2nd Embodiment. Explanatory drawing of wiping performed by adhering a foamy second liquid. Explanatory drawing of capping performed by adhering a foamy second liquid. The schematic diagram which shows the nozzle after adhering the 2nd liquid. The explanatory view of the fluid injection maintenance performed by the fluid injection apparatus of 2nd Embodiment. The schematic diagram which shows the modification example of the liquid injection part. The schematic diagram which shows the modification example of a fluid injection nozzle.

Hereinafter, as an example of the liquid injection device, an embodiment of an inkjet printer that injects liquid ink to print an image including characters, figures, and the like will be described with reference to the drawings.

(First Embodiment)
As shown in FIG. 1, the liquid injection device 7 includes a transport unit 713 that transports the sheet-shaped medium ST supported by the support base 712 in the transport direction Y along the surface of the support base 712, and the medium ST that is transported. It is provided with a printing unit 720 that injects ink as an example of the first liquid to print, and a heat generating unit 717 and a blowing unit 718 for drying the ink that has landed on the medium ST.

The support base 712, the transport unit 713, the heat generating unit 717, the blower unit 718, and the printing unit 720 are assembled to the printer main body 11a composed of a housing, a frame, and the like. In the printer main body 11a, the support base 712 extends in the width direction of the medium ST (the direction orthogonal to the paper surface in FIG. 1).

The transport unit 713 includes a transport roller pair 714a and a transport roller pair 714b, which are arranged on the upstream side and the downstream side of the support base 712 in the transport direction Y and are driven by the transport motor 749 (see FIG. 13), respectively. Further, the transport unit 713 is provided with a guide plate 715a and a guide plate 715b that are arranged on the upstream side of the transport roller pair 714a and the downstream side of the transport roller pair 714b in the transport direction Y to guide the medium ST while supporting the medium ST, respectively. There is.

Then, the transport unit 713 transports the medium ST along the surfaces of the guide plate 715a, the support base 712, and the guide plate 715b by rotating the transport roller pairs 714a and 714b while sandwiching the medium ST. In the present embodiment, the medium ST is continuously conveyed by being unwound from the roll sheet RS wound in a roll shape on the supply reel 716a. Then, the medium ST that is unwound from the roll sheet RS and continuously conveyed is wound into a roll by the take-up reel 716b after the ink is adhered by the printing unit 720 and the image is printed.

The printing unit 720 is guided by guide shafts 721 and 722 extending along the scanning direction X, which is the width direction of the medium ST orthogonal to the transport direction Y of the medium ST, and is guided by the carriage motor 748 (see FIG. 13). It includes a carriage 723 that can be reciprocated in the scanning direction X by power. In the present embodiment, the scanning direction X is a direction that intersects (for example, orthogonally) both the transport direction Y and the gravity direction Z.

The carriage 723 is supplied through two liquid injection units 1 (1A, 1B) for injecting ink, a liquid supply path 727 for supplying ink to the liquid injection unit 1 (1A, 1B), and a liquid supply path 727. A storage unit 730 for temporarily storing the ink, and a flow path adapter 728 connected to the storage unit 730 are provided. The storage unit 730 is held by a storage unit holder 725 attached to the carriage 723. In the present embodiment, the injection direction of the ink droplets (droplets) from the liquid injection unit 1 is the gravity direction Z.

The storage unit 730 includes a differential pressure valve 731 provided at an intermediate position of the liquid supply path 727 for supplying ink to the liquid injection unit 1. The differential pressure valve 731 is opened when the pressure of the ink on the downstream side becomes a predetermined negative pressure with respect to the atmospheric pressure due to the injection (consumption) of the ink in the liquid injection portions 1A and 1B located on the downstream side thereof. When the valve is opened, ink is supplied from the storage unit 730 to the liquid injection units 1A and 1B, and the negative pressure on the downstream side is eliminated, the valve is closed. The differential pressure valve 731 does not open even if the pressure of the ink on the downstream side becomes high, and allows the ink to be supplied from the upstream side (reservoir 730 side) to the downstream side (liquid injection unit 1 side). It functions as a one-way valve (check valve) that suppresses the backflow of ink from the downstream side to the upstream side.

The liquid injection portion 1 is attached to the lower end portion of the carriage 723 in a posture of facing the support base 712 at a predetermined distance in the gravity direction Z. On the other hand, the storage unit 730 is attached to the upper side of the carriage 723, which is opposite to the liquid injection unit 1 in the direction of gravity Z.

The upstream end of the supply tube 727a, which forms part of the liquid supply path 727, is a downstream end of a plurality of ink supply tubes 726 that can follow and deform the reciprocating carriage 723, and a part of the carriage 723. It is connected via a connecting portion 726a attached to the. Further, the downstream end of the supply tube 727a is connected to the flow path adapter 728 at a position above the storage portion 730. Therefore, for example, ink from an ink tank (not shown) containing ink is supplied to the storage unit 730 via the ink supply tube 726, the supply tube 727a, and the flow path adapter 728.

In the printing unit 720, in the process of moving (reciprocating) the carriage 723 in the scanning direction X, ink is applied to the medium ST on the support base 712 from the openings of the plurality of nozzles 21 (see FIG. 3) of the liquid injection unit 1. Ink. The heat generating portion 717 for heating and drying the ink that has landed on the medium ST is arranged at an upper position in the liquid injection device 7 at a predetermined length interval from the support base 712 in the gravity direction Z. Then, the printing unit 720 can reciprocate between the heat generating unit 717 and the support base 712 along the scanning direction X.

The heat generating portion 717 includes a heat generating member 717a such as an infrared heater and a reflecting plate 717b extending along the same scanning direction X as the extending direction of the support base 712, and is located in the area indicated by the one-point chain arrow in FIG. The ink adhering to the medium ST is heated by heat such as emitted infrared rays (for example, radiant heat). Further, the blower unit 718 that dries the ink adhering to the medium ST by blowing air is arranged at an upper position in the liquid injection device 7 so that the printing unit 720 can move back and forth with a space between the support base 712 and the support base 712.

A heat shield member 729 that blocks heat transfer from the heat generating portion 717 is provided at a position between the storage portion 730 and the heat generating portion 717 on the carriage 723. The heat shield member 729 is made of a metal material having good thermal conductivity such as stainless steel or aluminum, and covers at least the upper surface portion of the storage portion 730 facing the heat generating portion 717.

In the liquid injection device 7, the storage unit 730 is provided at least for each ink type. The liquid injection device 7 of the present embodiment includes a storage unit 730 in which colored ink is stored, and is capable of color printing and black-and-white printing. As an example, the ink colors of the coloring ink are cyan, magenta, yellow, black, and white. Each colored ink contains a preservative.

The white ink is used for base printing (also referred to as solid printing or fill printing) before color printing, for example, when the medium ST is a transparent or translucent film or a dark color medium. Will be done. Of course, the colored ink used can be arbitrarily selected, and may be, for example, three colors of cyan, magenta, and yellow. Further, as the coloring ink, in addition to the above three colors, at least one color such as light cyan, light magenta, light yellow, orange, green, and gray can be further added.

As shown in FIG. 2, the two liquid injection portions 1A and 1B attached to the lower end portion of the carriage 723 are arranged so as to be separated from each other by a predetermined distance in the scanning direction X and by a predetermined distance in the transport direction Y. ing. Further, at the lower end of the carriage 723, a temperature sensor 711 is provided at a position between the two liquid injection portions 1A and 1B in the scanning direction X.

The moving areas where the liquid injection units 1A and 1B can move in the scanning direction X are the printing area PA where ink can be landed from the nozzles 21 of the liquid injection units 1A and 1B when printing the medium ST, and the moving area which can move in the scanning direction X. The liquid injection units 1A and 1B include non-printing areas RA and LA, which are areas outside the printing area PA that do not face the medium ST being conveyed. The region corresponding to the print region PA in the scanning direction X is a heating region HA provided with a heat generating portion 717 for fixing the ink landing on the medium ST by heating.

The maximum width area in the scanning direction X at which the ink droplets ejected from the liquid injection units 1A and 1B can land on the maximum width medium ST conveyed on the support base 712 becomes the print area PA. There is. That is, the ink droplets ejected from the liquid injection units 1A and 1B onto the medium ST land in the print area PA. When the printing unit 720 has a borderless printing function, the printing area PA is slightly wider in the scanning direction X than the range of the medium ST having the maximum width to be conveyed.

The non-printing areas RA and LA exist on both sides of the printing area PA in the scanning direction X (on the right side and the left side in FIG. 2, respectively). In the non-printing area LA located on the left side of the printing area PA in FIG. 2, a fluid injection device 775 for performing maintenance of the liquid injection unit 1 is provided. On the other hand, the non-printing area RA located on the right side of the printing area PA in FIG. 2 is provided with a wiper unit 750, a flushing unit 751, and a cap unit 752.

The fluid injection device 775, the wiper unit 750, the flushing unit 751 and the cap unit 752 constitute a maintenance device 710 for performing maintenance on the liquid injection unit 1. The position where the cap unit 752 is located in the scanning direction X is the home position HP of the liquid injection portions 1A and 1B.

<About the configuration of the head unit>
Next, the configuration of the head unit 2 will be described in detail.
The liquid injection unit 1 has a plurality of (four in this embodiment) head units 2 provided for each color of ink (for each type of liquid).

As shown in FIG. 3, one head unit 2 has a large number of nozzles 21 openings for ejecting ink in one direction (conveyance direction Y in this embodiment) at a constant nozzle pitch (for example, 180). By lining up, the nozzle row NL is formed.

In the present embodiment, one head unit 2 is provided with two rows of nozzle rows NL arranged in the scanning direction X, so that two rows of nozzle rows NL located close to each other are provided in one liquid injection unit 1 in the scanning direction. A total of eight nozzle rows NL arranged at regular intervals in X are formed. When the two liquid injection units 1 project a large number of nozzles 21 constituting each other's nozzle row NL in the scanning direction X, the nozzles 21 at each end may have the same nozzle pitch. The positional relationship is in the direction Y.

As shown in FIG. 4, the head unit 2 includes a plurality of members such as a head main body 11 and a flow path forming member 40 fixed to one surface (upper surface) side of the head main body 11. The head body 11 has a flow path forming substrate 10, a communication plate 15 provided on one surface (lower surface) side of the flow path forming substrate 10, and a communication plate 15 on the opposite surface (lower surface) side of the flow path forming substrate 10. The nozzle plate 20 provided in the communication plate 20, the protective substrate 30 provided on the opposite side (upper side) of the communication plate 15 of the flow path forming substrate 10, and the surface side of the communication plate 15 provided with the nozzle plate 20. It also includes a compliance board 45.

As the flow path forming substrate 10, a metal such as stainless steel or Ni, a ceramic material typified by ZrO2 or Al2O3, a glass ceramic material, an oxide such as MgO or LaAlO3 can be used. In the present embodiment, the flow path forming substrate 10 is made of a silicon single crystal substrate.

As shown in FIG. 5, a plurality of nozzles 21 for ejecting ink from a pressure generating chamber 12 partitioned by a plurality of partition walls are arranged side by side on the flow path forming substrate 10 by anisotropic etching from one surface side. They are arranged side by side along the direction in which they are formed. The flow path forming substrate 10 is provided with a plurality of rows (two rows in this embodiment) in which pressure generating chambers 12 are arranged side by side in the transport direction Y so as to be lined up in the scanning direction X.

The flow path forming substrate 10 is supplied with a flow path resistance of ink flowing into the pressure generating chamber 12 having a smaller opening area than the pressure generating chamber 12 on one end side in the transport direction Y of the pressure generating chamber 12. A road or the like may be provided.

As shown in FIGS. 4 and 5, a communication plate 15 and a nozzle plate 20 are laminated in the direction of gravity Z on one surface (lower surface) side of the flow path forming substrate 10. That is, the liquid injection unit 1 is a nozzle in which a communication plate 15 provided on one surface of the flow path forming substrate 10 and a nozzle 21 provided on the side opposite to the flow path forming substrate 10 of the communication plate 15 are formed. A plate 20 is provided.

The communication plate 15 is provided with a nozzle communication passage 16 that communicates the pressure generating chamber 12 and the nozzle 21. The communication plate 15 has a larger area than the flow path forming substrate 10, and the nozzle plate 20 has a smaller area than the flow path forming substrate 10. By providing the communication plate 15 in this way, the nozzle 21 of the nozzle plate 20 and the pressure generating chamber 12 can be separated from each other. Therefore, the ink in the pressure generating chamber 12 is caused by the evaporation of water in the ink from the nozzle 21. It becomes difficult to thicken. Further, since the nozzle plate 20 only needs to cover the opening of the nozzle communication passage 16 that communicates the pressure generating chamber 12 and the nozzle 21, the area of the nozzle plate 20 can be made relatively small, and the cost can be reduced. Can be done.

As shown in FIG. 5, the communication plate 15 is provided with a first manifold portion 17 and a second manifold portion 18 (throttle flow path, orifice flow path) forming a part of the common liquid chamber (manifold) 100. Has been done. The first manifold portion 17 is provided so as to penetrate the communication plate 15 in the thickness direction (gravity direction Z which is the stacking direction between the communication plate 15 and the flow path forming substrate 10). The second manifold portion 18 is provided so as to open to the nozzle plate 20 side of the communication plate 15 without penetrating the communication plate 15 in the thickness direction.

Further, the communication plate 15 is provided with a supply communication passage 19 that communicates with one end of the pressure generation chamber 12 in the transport direction Y independently for each pressure generation chamber 12. The supply communication passage 19 communicates the second manifold portion 18 with the pressure generating chamber 12.

As such a communication plate 15, a metal such as stainless steel or nickel (Ni), ceramics such as zirconium (Zr), or the like can be used. The communication plate 15 is preferably made of a material having the same coefficient of linear expansion as that of the flow path forming substrate 10. That is, when a material having a linear expansion coefficient significantly different from that of the flow path forming substrate 10 is used as the communication plate 15, the flow path forming substrate 10 and the communication plate 15 are warped due to heating or cooling. In the present embodiment, by using the same material as the flow path forming substrate 10, that is, the silicon single crystal substrate as the communication plate 15, it is possible to suppress the occurrence of warpage due to heat, cracks due to heat, peeling, and the like.

Of both sides of the nozzle plate 20, the surface (lower surface) for ejecting ink droplets, that is, the surface opposite to the pressure generating chamber 12, is referred to as the liquid injection surface 20a, and the opening of the nozzle 21 that opens to the liquid injection surface 20a is the nozzle. Called an opening.

As the nozzle plate 20, for example, a metal such as stainless steel (SUS), an organic substance such as a polyimide resin, a silicon single crystal substrate, or the like can be used. By using a silicon single crystal substrate as the nozzle plate 20, the linear expansion coefficients of the nozzle plate 20 and the communicating plate 15 are made equal, and the occurrence of warpage due to heating and cooling, cracks due to heat, peeling, etc. is suppressed. can do.

On the other hand, a diaphragm 50 is formed on the side of the flow path forming substrate 10 opposite to the communication plate 15. In the present embodiment, as the diaphragm 50, an elastic film 51 made of silicon oxide provided on the flow path forming substrate 10 side and an insulator film 52 made of zirconium oxide provided on the elastic film 51 are provided. There is. The liquid flow path of the pressure generating chamber 12 or the like is formed by anisotropic etching of the flow path forming substrate 10 from one surface side (the surface side to which the nozzle plate 20 is joined), and the pressure generating chamber 12 or the like is formed. The other surface of the liquid flow path such as the above is defined by an elastic film 51.

An actuator (piezoelectric actuator) 130 having a first electrode 60, a piezoelectric layer 70, and a second electrode 80, which is the pressure generating means of the present embodiment, is provided on the diaphragm 50 of the flow path forming substrate 10. There is. Here, the actuator 130 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80.

Generally, one electrode of the actuator 130 is used as a common electrode, and the other electrode is patterned for each pressure generating chamber 12. In the present embodiment, the first electrode 60 is provided continuously over the plurality of actuators 130 to form a common electrode, and the second electrode 80 is provided independently for each actuator 130 to form an individual electrode.

Of course, there is no problem even if this is reversed due to the convenience of the drive circuit and wiring. In the above-mentioned example, the diaphragm 50 is composed of the elastic film 51 and the insulator film 52, but the diaphragm 50 is not limited to this, of course. For example, either the elastic film 51 or the insulator film 52 may be provided as the diaphragm 50, or the first electrode may be provided without providing the elastic film 51 and the insulator film 52 as the diaphragm 50. Only 60 may act as a diaphragm. Further, the actuator 130 itself may substantially also serve as a diaphragm.

The piezoelectric layer 70 is made of an oxide piezoelectric material having a polarized structure, and can be made of, for example, a perovskite-type oxide represented by the general formula ABO3, and is a lead-based piezoelectric material containing lead or lead-free lead-free material. A system piezoelectric material or the like can be used.

Further, the second electrode 80, which is an individual electrode of the actuator 130, is drawn from the vicinity of the end opposite to the supply passage 19 and extends onto the diaphragm 50, for example, gold ( One end of the lead electrode 90 made of Au) or the like is connected to each other.

Further, a wiring board 121, which is an example of a flexible wiring board provided with a drive circuit 120 for driving the actuator 130, is connected to the other end of the lead electrode 90. As the wiring board 121, a flexible sheet-like material, for example, a COF substrate or the like can be used.

On one surface of the wiring board 121, a second terminal row 123 in which a plurality of second terminals (wiring terminals) 122 electrically connected to the first terminal 311 of the head board 300, which will be described later, are arranged side by side is formed. .. A plurality of the second terminals 122 of the present embodiment are arranged side by side along the scanning direction X to form a second terminal row 123. It is not necessary to provide the drive circuit 120 on the wiring board 121. That is, the wiring board 121 is not limited to the COF board, and may be an FFC, an FPC, or the like.

A protective substrate 30 having substantially the same size as the flow path forming substrate 10 is joined to the surface of the flow path forming substrate 10 on the actuator 130 side. The protective substrate 30 has a holding portion 31 which is a space for protecting the actuator 130.

The holding portion 31 has a concave shape that opens toward the flow path forming substrate 10 side without penetrating the protective substrate 30 in the gravity direction Z, which is the thickness direction. Further, the holding portion 31 is independently provided for each row composed of the actuators 130 arranged side by side in the scanning direction X. That is, the holding portions 31 are provided so as to accommodate rows arranged side by side in the scanning direction X of the actuator 130, and each row of the actuator 130, that is, two are arranged side by side in the conveying direction Y. Such a holding portion 31 may have a space that does not hinder the movement of the actuator 130, and the space may or may not be sealed.

The protective substrate 30 has a through hole 32 penetrating in the gravity direction Z, which is the thickness direction. The through hole 32 is provided between the two holding portions 31 arranged side by side in the transport direction Y over the scanning direction X which is the parallel direction of the plurality of actuators 130. That is, the through hole 32 is an opening having long sides in the juxtaposed direction of the plurality of actuators 130. The other end of the lead electrode 90 is extended so as to be exposed in the through hole 32, and the lead electrode 90 and the wiring board 121 are electrically connected in the through hole 32.

As such a protective substrate 30, it is preferable to use a material substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc., and in the present embodiment, the same material as the flow path forming substrate 10. It was formed using the silicon single crystal substrate of. The method of joining the flow path forming substrate 10 and the protective substrate 30 is not particularly limited. For example, in the present embodiment, the flow path forming substrate 10 and the protective substrate 30 are joined via an adhesive (not shown). Has been done.

The head unit 2 having such a configuration includes a flow path forming member 40 that defines a common liquid chamber 100 communicating with a plurality of pressure generating chambers 12 together with the head main body 11. The flow path forming member 40 has substantially the same shape as the communication plate 15 described above in a plan view, and is joined to the protective substrate 30 and also to the communication plate 15 described above. Specifically, the flow path forming member 40 has a recess 41 having a depth for accommodating the flow path forming substrate 10 and the protective substrate 30 on the protective substrate 30 side. The recess 41 has an opening area wider than the surface of the protective substrate 30 joined to the flow path forming substrate 10. Then, the opening surface of the recess 41 on the nozzle plate 20 side is sealed by the communication plate 15 in a state where the flow path forming substrate 10 and the like are housed in the recess 41. As a result, a third manifold portion 42 is defined on the outer peripheral portion of the flow path forming substrate 10 by the flow path forming member 40 and the head main body 11. Then, the first manifold portion 17 and the second manifold portion 18 provided on the communication plate 15 and the third manifold portion 42 defined by the flow path forming member 40 and the head main body 11 are common to this embodiment. The liquid chamber 100 is configured.

That is, the common liquid chamber 100 includes a first manifold portion 17, a second manifold portion 18, and a third manifold portion 42. Further, the common liquid chamber 100 of the present embodiment is arranged on both outer sides of the two rows of pressure generating chambers 12 in the transport direction Y, and is provided on both outer sides of the two rows of pressure generating chambers 12. The liquid chambers 100 are independently provided in the head unit 2 so as not to communicate with each other. That is, one common liquid chamber 100 is provided in communication with each row of the pressure generating chambers 12 of the present embodiment (rows arranged side by side in the scanning direction X). In other words, a common liquid chamber 100 is provided for each nozzle group. Of course, the two common liquid chambers 100 may communicate with each other.

As described above, the flow path forming member 40 is a member that forms the flow path (common liquid chamber 100) of the ink supplied to the head main body 11, and has an introduction port 44 communicating with the common liquid chamber 100. .. That is, the introduction port 44 is an opening serving as an inlet for introducing the ink supplied to the head main body 11 into the common liquid chamber 100.

Further, the flow path forming member 40 is provided with a connection port 43 in which the wiring board 121 is inserted so as to communicate with the through hole 32 of the protective board 30. The other end of the wiring board 121 extends in the penetrating direction of the through hole 32 and the connection port 43, that is, in the gravity direction Z, on the side opposite to the ink droplet jetting direction.

As the material of such a flow path forming member 40, for example, resin, metal, or the like can be used. Incidentally, by molding a resin material as the flow path forming member 40, mass production can be performed at low cost.

Further, a compliance board 45 is provided on the surface of the communication plate 15 where the first manifold portion 17 and the second manifold portion 18 open. The compliance substrate 45 has substantially the same size as the communication plate 15 described above in a plan view, and is provided with a first exposed opening 45a that exposes the nozzle plate 20. Then, in a state where the compliance substrate 45 exposes the nozzle plate 20 by the first exposed opening 45a, the openings of the first manifold portion 17 and the second manifold portion 18 on the liquid injection surface 20a side are sealed. That is, the compliance board 45 defines a part of the common liquid chamber 100.

In this embodiment, such a compliance substrate 45 includes a sealing film 46 and a fixed substrate 47. The sealing film 46 is made of a flexible film-like thin film (for example, a thin film having a thickness of 20 μm or less formed of polyphenylene sulfide (PPS) or the like), and the fixed substrate 47 is made of stainless steel (SUS) or the like. It is made of a hard material such as metal. Since the region of the fixed substrate 47 facing the common liquid chamber 100 is an opening 48 completely removed in the thickness direction, one surface of the common liquid chamber 100 is a flexible sealing film 46. It is a compliance unit 49 which is a flexible portion sealed only by. In the present embodiment, one compliance unit 49 is provided corresponding to one common liquid chamber 100. That is, in the present embodiment, since two common liquid chambers 100 are provided, two compliance portions 49 are provided on both sides in the transport direction Y with the nozzle plate 20 interposed therebetween.

In the head unit 2 having such a configuration, when the ink is ejected, the ink is taken in through the introduction port 44, and the inside of the flow path is filled with the ink from the common liquid chamber 100 to the nozzle 21. After that, according to the signal from the drive circuit 120, a voltage is applied to each actuator 130 corresponding to the pressure generating chamber 12, so that the diaphragm 50 is flexed and deformed together with the actuator 130. As a result, the pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the predetermined nozzle 21.

<About the configuration of the liquid injection part>
Next, the liquid injection unit 1 having the head unit 2 will be described in detail.
As shown in FIG. 6, the liquid injection unit 1 includes four head units 2, a flow path member 200 including a holder member that holds the head unit 2 and supplies ink to the head unit 2, and a flow path member 200. It includes a held head substrate 300 and a wiring substrate 121 which is an example of a flexible wiring substrate.

Note that FIG. 7 shows a plan view of the liquid injection unit 1 in which the seal member 230 and the upstream flow path member 210 are not shown.
As shown in FIG. 8, the flow path member 200 is arranged between the upstream flow path member 210, the downstream flow path member 220 which is an example of the holder member, and the upstream flow path member 210 and the downstream flow path member 220. The seal member 230 is provided.

The upstream flow path member 210 has an upstream flow path 500 that serves as a flow path for ink. In the present embodiment, the upstream flow path member 210 is configured by stacking the first upstream flow path member 211, the second upstream flow path member 212, and the third upstream flow path member 213 in the direction of gravity Z. .. Each of these members is provided with a first upstream flow path 501, a second upstream flow path 502, and a third upstream flow path 503, and the upstream flow path 500 is formed by connecting these.

The upstream flow path member 210 is not limited to such an embodiment, and may be a single member or may be composed of two or more members. Further, the stacking direction of the plurality of members constituting the upstream flow path member 210 is not particularly limited, and may be the scanning direction X and the transport direction Y.

The first upstream flow path member 211 has a connecting portion 214 connected to a liquid holding means such as an ink tank or an ink cartridge in which ink (liquid) is held on the side opposite to the downstream flow path member 220. In the present embodiment, the connecting portion 214 is formed to protrude like a needle. A liquid holding portion such as an ink cartridge may be directly connected to the connecting portion 214, or a liquid holding portion such as an ink tank may be connected via a supply pipe such as a tube.

The first upstream flow path member 211 is provided with a first upstream flow path 501. The first upstream flow path 501 opens at the top surface of the connecting portion 214 and extends in the gravity direction Z or in a direction orthogonal to the gravity direction Z, that is, depending on the position of the second upstream flow path 502 described later. It is composed of a flow path or the like extending in the plane including the scanning direction X and the transport direction Y. Further, a guide wall 215 (see FIG. 6) for positioning the liquid holding portion is provided around the connecting portion 214 of the first upstream flow path member 211.

The second upstream flow path member 212 has a second upstream flow path 502 that is fixed on the side opposite to the connection portion 214 of the first upstream flow path member 211 and communicates with the first upstream flow path 501. Further, on the downstream side of the second upstream flow path 502 (the third upstream flow path member 213 side), a first liquid pool portion 502a having a wider inner diameter than the second upstream flow path 502 is provided.

The third upstream flow path member 213 is provided on the side of the second upstream flow path member 212 opposite to the first upstream flow path member 211. Further, the third upstream flow path member 213 is provided with a third upstream flow path 503. The opening portion of the third upstream flow path 503 on the second upstream flow path 502 side is a second liquid pool portion 503a that is widened according to the first liquid pool portion 502a. A filter 216 for removing air bubbles and foreign substances contained in the ink is provided in the opening portion of the second liquid pool portion 503a (between the first liquid pool portion 502a and the second liquid pool portion 503a). As a result, the ink supplied from the second upstream flow path 502 (first liquid pool portion 502a) is supplied to the third upstream flow path 503 (second liquid pool portion 503a) via the filter 216.

As the filter 216, for example, a mesh-like body such as a wire mesh or a resin mesh, a porous body, or a metal plate having fine through holes can be used. Specific examples of the mesh-like body include metal mesh filters and metal fibers, for example, SUS fine wires made into a felt shape, compression-sintered metal sintered filters, electroforming metal filters, and electron beam processing. A metal filter, a laser beam processed metal filter, or the like can be used. In particular, it is preferable that the bubble point pressure (the pressure at which the meniscus formed by opening the filter breaks) does not vary, and a filter having a high-definition hole diameter is suitable. Further, the filtration particle size of the filter is preferably smaller than the diameter of the nozzle opening, for example, when the nozzle opening is circular, in order to prevent foreign substances in the ink from reaching the nozzle opening.

When a stainless steel mesh filter is used as the filter 216, the filtration particle size of the filter is the nozzle opening (for example, when the nozzle opening is circular, the diameter of the nozzle opening is 20 μm) in order to prevent foreign matter in the ink from reaching the nozzle opening. ) Is preferable, and in this case, the bubble point pressure (pressure at which the meniscus formed by opening the filter is broken) generated by the ink (surface tension 28 mN / m) is 3 to 5 kPa. Is. Further, the bubble point pressure (pressure at which the meniscus formed by opening the filter is broken) generated by the ink when the twill tatami mat weave (filtration particle size 5 um) is adopted is 0 to 15 kPa.

The third upstream flow path 503 is branched into two on the downstream side (opposite side of the second upstream flow path) from the second liquid pool portion 503a, and the third upstream flow path 503 is the third upstream flow path. The first discharge port 504A and the second discharge port 504B are opened on the surface of the member 213 on the downstream flow path member 220 side. Hereinafter, when the first discharge port 504A and the second discharge port 504B are not distinguished, they are referred to as a discharge port 504.

That is, the upstream flow path 500 corresponding to one connection portion 214 has a first upstream flow path 501, a second upstream flow path 502, and a third upstream flow path 503, and the upstream flow path 500 is a downstream flow path member. Two outlets 504 (first outlet 504A and second outlet 504B) are opened on the 220 side. In other words, the two discharge ports 504 (first discharge port 504A and second discharge port 504B) are provided so as to communicate with a common flow path.

Further, on the downstream flow path member 220 side of the third upstream flow path member 213, a third protrusion 217 protruding toward the downstream flow path member 220 side is provided. The third protrusion 217 is provided for each third upstream flow path 503, and a discharge port 504 is provided at the tip end surface of the third protrusion 217.

The first upstream flow path member 211, the second upstream flow path member 212, and the third upstream flow path member 213 provided with such an upstream flow path 500 are integrally laminated by, for example, an adhesive or welding. ing. Although the first upstream flow path member 211, the second upstream flow path member 212, and the third upstream flow path member 213 can be fixed with screws, clamps, or the like, the first upstream flow path 501 to the third upstream flow path can be fixed. In order to prevent ink (liquid) from leaking from the connecting portion up to 503, it is preferable to join with an adhesive or welding.

In the present embodiment, one upstream flow path member 210 is provided with four connecting portions 214, and one upstream flow path member 210 is provided with four independent upstream flow paths 500. Then, ink is supplied to each upstream flow path 500 corresponding to each of the four head units 2. One upstream flow path 500 branches into two, communicates with the downstream flow path 600 described later, and is connected to each of the two introduction ports 44 of the head unit 2.

In the present embodiment, the configuration in which the upstream flow path 500 is branched into two on the downstream side (downstream flow path member 220 side) of the filter 216 is illustrated, but the present invention is not particularly limited to this, and the downstream side of the filter 216 is not particularly limited. The upstream flow path 500 may be branched into three or more. Further, one upstream flow path 500 may not be branched downstream of the filter 216.

The downstream flow path member 220 is an example of a holder member having a downstream flow path 600 that is joined to the upstream flow path member 210 and communicates with the upstream flow path 500. The downstream flow path member 220 according to the present embodiment is composed of a first downstream flow path member 240 which is an example of the first member and a second downstream flow path member 250 which is an example of the second member.

The downstream flow path member 220 has a downstream flow path 600 that serves as a flow path for ink. The downstream flow path 600 according to the present embodiment is composed of two types of downstream flow paths 600A and downstream flow paths 600B having different shapes.

The first downstream flow path member 240 is a member formed in a substantially flat plate shape. Further, the second downstream flow path member 250 is provided with a first accommodating portion 251 as a recess on the surface on the upstream flow path member 210 side and a second accommodating portion 252 as a recess on the surface opposite to the upstream flow path member 210. It is a member.

The first accommodating portion 251 is sized to accommodate the first downstream flow path member 240. Further, the second accommodating portion 252 is sized to accommodate four head units 2. The second accommodating portion 252 according to the present embodiment can accommodate four head units 2.

The first downstream flow path member 240 is formed with a plurality of first protrusions 241 on the surface on the upstream flow path member 210 side. Each of the first protrusions 241 is provided so as to face the third protrusion 217 provided with the first discharge port 504A among the third protrusions 217 provided on the upstream flow path member 210. In this embodiment, four first protrusions 241 are provided.

Further, the first downstream flow path member 240 is provided with a first flow path 601 that penetrates in the direction of gravity Z and opens on the top surface (the surface facing the upstream flow path member 210) of the first protrusion 241. There is. The third protrusion 217 and the first protrusion 241 are joined via a seal member 230, and the first discharge port 504A and the first flow path 601 communicate with each other.

Further, the first downstream flow path member 240 is formed with a plurality of second through holes 242 penetrating in the direction of gravity Z. Each second through hole 242 is formed at a position through which the second protrusion 253 formed in the second downstream flow path member 250 is inserted. In this embodiment, four second through holes 242 are provided.

Further, the first downstream flow path member 240 is formed with a plurality of first insertion holes 243 through which the wiring board 121 electrically connected to the head unit 2 is inserted. Specifically, each first insertion hole 243 penetrates in the direction of gravity Z and communicates with the second insertion hole 255 of the second downstream flow path member 250 and the third insertion hole 302 of the head substrate 300. It is formed. In the present embodiment, four first insertion holes 243 are provided corresponding to the wiring boards 121 provided in the four head units 2. Further, the first downstream flow path member 240 is provided with a support portion 245 that protrudes toward the head substrate 300 and has a receiving surface.

The second downstream flow path member 250 is formed with a plurality of second protrusions 253 on the bottom surface of the first accommodating portion 251. Each of the second protrusions 253 is provided so as to face the third protrusion 217 provided with the second discharge port 504B among the third protrusions 217 provided on the upstream flow path member 210. In this embodiment, four second protrusions 253 are provided. Further, the second downstream flow path member 250 penetrates in the direction of gravity Z and opens to the top surface of the second protrusion 253 and the bottom surface of the second accommodating portion 252 (the surface facing the head unit 2). 600B is provided. The third protrusion 217 and the second protrusion 253 are joined via a seal member 230, and the second discharge port 504B and the downstream flow path 600B communicate with each other.

Further, the second downstream flow path member 250 is formed with a plurality of third flow paths 603 penetrating in the direction of gravity Z. Each third flow path 603 is open to the bottom surface of the first accommodating portion 251 and the second accommodating portion 252. In this embodiment, four third flow paths 603 are provided.

A plurality of groove portions 254 continuous with the third flow path 603 are formed on the bottom surface of the first accommodating portion 251 of the second downstream flow path member 250. The groove portion 254 is sealed in the first downstream flow path member 240 housed in the first storage portion 251 to form the second flow path 602. That is, the second flow path 602 is a flow path defined by the groove portion 254 and the surface of the first downstream flow path member 240 on the side of the second downstream flow path member 250. The second flow path 602 corresponds to a flow path provided between the first member and the second member according to the claim.

Further, the second downstream flow path member 250 is formed with a plurality of second insertion holes 255 through which the wiring board 121 electrically connected to the head unit 2 is inserted. Specifically, each of the second insertion holes 255 is formed so as to penetrate in the gravity direction Z and communicate with the first insertion hole 243 of the first downstream flow path member 240 and the connection port 43 of the head unit 2. .. In the present embodiment, four second insertion holes 255 are provided corresponding to the wiring boards 121 provided on the four head units 2.

The downstream flow path 600A is formed by communicating the first flow path 601, the second flow path 602, and the third flow path 603 described above. Here, the second flow path 602 is formed by sealing the groove formed on one surface of the first downstream flow path member 240 with the second downstream flow path member 250. By joining the first downstream flow path member 240 and the second downstream flow path member 250, the second flow path 602 can be easily formed in the downstream flow path member 220.

The second flow path 602 is an example of a flow path extending in the horizontal direction. The fact that the second flow path 602 extends in the horizontal direction means that a component (vector) in the scanning direction X or the transport direction Y is included in the extending direction of the second flow path 602. Since the second flow path 602 extends in the horizontal direction, the height of the liquid injection portion 1 in the gravity direction Z can be reduced. If the second flow path 602 is tilted with respect to the horizontal direction, the height of the liquid injection unit 1 is slightly required.

Incidentally, the extending direction of the second flow path 602 is the direction in which the ink (liquid) in the second flow path 602 flows. Therefore, the second flow path 602, which is provided in the horizontal direction (direction orthogonal to the gravity direction Z), intersects the gravity direction Z and the horizontal direction (in-plane direction of the scanning direction X and the transport direction Y). Including those provided in the above. In the present embodiment, the first flow path 601 and the third flow path 603 are provided along the gravity direction Z, and the second flow path 602 is provided along the horizontal direction (transportation direction Y). The first flow path 601 and the third flow path 603 may be provided in a direction intersecting the gravity direction Z.

Of course, the downstream flow path 600A is not limited to this, and a flow path other than the first flow path 601, the second flow path 602, and the third flow path 603 may exist. Further, the downstream flow path 600A is not composed of the first flow path 601 and the second flow path 602 and the third flow path 603, but may be composed of one flow path.

As described above, the downstream flow path 600B is formed as a through hole that penetrates the second downstream flow path member 250 in the gravity direction Z. Of course, the downstream flow path 600B is not limited to such an embodiment, and may be formed along a direction intersecting the gravity direction Z, or a plurality of flow paths may be communicated with each other as in the downstream flow path 600A. It may be configured as follows.

Such a downstream flow path 600A and a downstream flow path 600B are formed one by one for one head unit 2. That is, the downstream flow path member 220 is provided with a total of four sets of the downstream flow path 600A and the downstream flow path 600B.

Of the openings at both ends of the downstream flow path 600A, the opening of the first flow path 601 through which the first discharge port 504A communicates is the first inflow port 610, and the opening of the third flow path 603 that opens into the second accommodating portion 252. Is the first outlet 611.

Of the openings at both ends of the downstream flow path 600B, the opening of the downstream flow path 600B through which the second discharge port 504B communicates is the second inflow port 620, and the opening of the downstream flow path 600B that opens to the second accommodating portion 252 is the first. The second outlet is 621. Hereinafter, when the downstream flow path 600A and the downstream flow path 600B are not distinguished, they are referred to as the downstream flow path 600.

As shown in FIG. 6, the downstream flow path member 220 (holder member) holds the head unit 2 on the lower side. Specifically, a plurality of (four in this embodiment) head units 2 are accommodated in the second accommodating portion 252 of the downstream flow path member 220.

As shown in FIG. 8, the head unit 2 is provided with two introduction ports 44 each. The first outlet 611 and the second outlet 621 of the downstream flow path 600 (downstream flow path 600A and downstream flow path 600B) are provided in the downstream flow path member 220 according to the opening position of each introduction port 44. ..

Each introduction port 44 of the head unit 2 is aligned so as to communicate with the first outlet 611 and the second outlet 621 of the downstream flow path 600 opened at the bottom surface of the second accommodating portion 252. The head unit 2 is fixed to the second accommodating portion 252 by an adhesive 227 provided around each introduction port 44. By fixing the head unit 2 to the second accommodating portion 252 in this way, the first outlet 611 and the second outlet 621 of the downstream flow path 600 and the introduction port 44 communicate with each other, and ink is applied to the head unit 2. It is supposed to be supplied.

The head substrate 300 is placed on the upstream side of the downstream flow path member 220 (holder member). Specifically, the head substrate 300 is placed on the surface of the downstream flow path member 220 on the upstream flow path member 210 side. The head substrate 300 is a member to which a wiring board 121 is connected and electrical components such as a circuit and a resistor that control the injection operation of the liquid injection unit 1 via the wiring board 121 are mounted.

As shown in FIG. 6, a plurality of first terminals (electrode terminals) 311 to which the second terminal row 123 of the wiring board 121 is electrically connected are arranged on the surface of the head substrate 300 on the upstream flow path member 210 side. The provided first terminal row 310 is formed. A plurality of the first terminals 311 of the present embodiment are arranged side by side along the scanning direction X to form a first terminal row 310. In the present embodiment, the first terminal row 310 is an example of a mounting region electrically connected to the wiring board 121.

Further, the head substrate 300 is formed with a plurality of third insertion holes 302 through which the wiring board 121 electrically connected to the head unit 2 is inserted. Specifically, each of the third insertion holes 302 is formed so as to penetrate in the gravity direction Z and communicate with the first insertion hole 243 of the first downstream flow path member 240. In the present embodiment, four third insertion holes 302 are provided corresponding to the wiring boards 121 provided on the four head units 2.

Further, the head substrate 300 is provided with a third through hole 301 penetrating in the direction of gravity Z. The third through hole 301 is formed through which the first protrusion 241 of the first downstream flow path member 240 and the second protrusion 253 of the second downstream flow path member 250 are inserted. In the present embodiment, a total of eight third through holes 301 are provided so as to face the first protrusion 241 and the second protrusion 253.

The shape of the third through hole 301 formed in the head substrate 300 is not limited to the above-described embodiment. For example, a common through hole through which the first protrusion 241 and the second protrusion 253 are inserted may be used as the insertion hole. That is, the head substrate 300 is formed with insertion holes, notches, and the like so as not to interfere with the connection between the downstream flow path 600 of the downstream flow path member 220 and the upstream flow path 500 of the upstream flow path member 210. Just do it.

As shown in FIG. 8, a seal member 230 is provided between the head substrate 300 and the upstream flow path member 210. As the material of the seal member 230, a material (elastic material) that has liquid resistance to a liquid such as ink used in the liquid injection unit 1 and is elastically deformable (elastic material), for example, rubber or elastomer may be used. can.

The seal member 230 is a plate-shaped member in which a continuous passage 232 penetrating in the direction of gravity Z and a fourth protrusion 231 projecting toward the downstream flow path member 220 are formed. In the present embodiment, eight communication passages 232 and the fourth protrusion 231 are formed corresponding to the upstream flow paths 500 and the downstream flow paths 600.

An annular first recess 233 into which the third protrusion 217 is inserted is provided on the upstream flow path member 210 side of the seal member 230. The first recess 233 is provided at a position facing the fourth protrusion 231.

The fourth protrusion 231 projects toward the downstream flow path member 220, and is provided at a position facing the first protrusion 241 and the second protrusion 253 of the downstream flow path member 220. The top surface of the fourth protrusion 231 (the surface facing the downstream flow path member 220) is provided with a second recess 234 into which the first protrusion 241 and the second protrusion 253 are inserted.

The communication passage 232 penetrates the seal member 230 in the direction of gravity Z, and one end thereof opens in the first recess 233 and the other end opens in the second recess 234. Then, between the tip surface of the third protrusion 217 inserted into the first recess 233 and the tip surfaces of the first protrusion 241 and the second protrusion 253 inserted into the second recess 234, the fourth protrusion The portion 231 is held in a state where a predetermined pressure is applied in the direction of gravity Z. Therefore, the upstream flow path 500 and the downstream flow path 600 are communicated with each other in a sealed state via the communication passage 232.

A cover head 400 is attached to the second accommodating portion 252 side (lower side) of the downstream flow path member 220. The cover head 400 is a member to which the head unit 2 is fixed and is fixed to the downstream flow path member 220, and is provided with a second exposed opening 401 that exposes the nozzle 21. In the present embodiment, the second exposed opening 401 has a size that exposes the nozzle plate 20, that is, has substantially the same opening as the first exposed opening 45a of the compliance substrate 45.

The cover head 400 is joined to the side of the compliance substrate 45 opposite to the communication plate 15, and seals the space on the side opposite to the flow path (common liquid chamber 100) of the compliance portion 49. By covering the compliance unit 49 with the cover head 400 in this way, it is possible to prevent the compliance unit 49 from being destroyed even if it comes into contact with the medium ST. Further, it is possible to suppress the ink (liquid) from adhering to the compliance unit 49 and wipe off the ink (liquid) adhering to the surface of the cover head 400 with, for example, a wiper blade, and the medium ST is attached to the cover head 400. It is possible to prevent stains with the adhered ink or the like. Although not shown in particular, the space between the cover head 400 and the compliance unit 49 is open to the atmosphere. Of course, the cover head 400 may be provided independently for each head unit 2.

<About the configuration of maintenance equipment>
Next, the configuration of the maintenance device 710 will be described in detail.
As shown in FIG. 9, the non-printing area RA includes a wiping area WA provided with the wiper unit 750, a receiving area FA provided with the flushing unit 751, and a maintenance area MA provided with the cap unit 752. .. That is, in the non-printing area RA, the wiping area WA, the receiving area FA, and the maintenance area MA are located on the wiping area WA, the receiving area FA, and the maintenance area MA from the print area PA (see FIG. 2) side in the scanning direction X. They are arranged in order.

The wiper unit 750 has a wiping member 750a that wipes the liquid injection unit 1. The wiping member 750a of the present embodiment is movable, and the wiping operation is performed by the power of the wiping motor 753. The flushing unit 751 has a liquid receiving unit 751a that receives ink droplets ejected by the liquid ejecting unit 1.

The liquid receiving unit 751a of the present embodiment is composed of a belt, and moves the belt by the power of the flushing motor 754 at a predetermined time when it can be considered that the amount of ink stain due to flushing of the belt exceeds the specified amount. Flushing refers to an operation of forcibly ejecting (discharging) ink droplets from all nozzles 21 regardless of printing for the purpose of preventing and eliminating clogging of nozzles 21.

The cap unit 752 can contact the liquid injection portions 1A and 1B so as to surround the opening of the nozzle 21 when the liquid injection portions 1A and 1B are located at the home position HP as shown by the alternate long and short dash line in FIG. It has two cap portions 752a. The two cap portions 752a are configured to be movable between a contact position in contact with the liquid injection portion 1 at the home position HP and a retracted position away from the liquid injection portion 1 by the power of the capping motor 755. ..

The wiper unit 750 includes a movable housing 759 that can be reciprocated on a pair of rails 758 extending along the transport direction Y by the power of the wiping motor 753. In the housing 759, a feeding shaft 760 and a winding shaft 761 located at a predetermined distance in the wiping direction (same as the transport direction Y) are rotatably supported. The feed shaft 760 supports the feed roll 763 formed by the unused cloth sheet 762, and the take-up shaft 761 supports the take-up roll 764 formed by the used cloth sheet 762.

The cloth sheet 762 located between the feeding roll 763 and the winding roll 764 is wound around and pressed on the upper surface of the pressing roller 765 which is partially projected upward from an opening (not shown) in the center of the upper surface of the housing 759. A semi-cylindrical (convex) wiping member 750a is formed at a portion wound around the roller 765. The wiping member 750a is in a state of being urged upward.

The housing 759 is wiped in a wiping direction via a cassette accommodating the feeding roll 763 and the winding roll 764, and a power transmission mechanism (for example, a rack and pinion mechanism) (for example, a rack and pinion mechanism) guided by the rail 758 and powered by the wiping motor 753. It is composed of a holder that can reciprocate in (in the present embodiment, a direction along the transport direction Y). The housing 759 is driven in the forward rotation and the reverse rotation of the wiping motor 753, so that the retracting position shown in FIG. 9 and the wiping position where the wiping member 750a finishes wiping the liquid injection portion 1 are in the transport direction Y. Move one round trip.

At this time, when the forward movement of the housing 759 is completed, the power transmission mechanism is switched to a state in which the wiping motor 753 and the take-up shaft 761 are connected so as to be able to transmit power, and the power when the wiping motor 753 is reversely driven is used. A removing operation of the housing 759 and a predetermined amount of winding operation of the cloth sheet 762 on the winding roll 764 are performed. The two liquid injection parts 1A and 1B are sequentially moved with respect to the wiping area WA, and the wiping for the two liquid injection parts 1A and 1B by one reciprocating movement of the housing 759 is individually moved to the wiping area WA. Will be done.

The flushing unit 751 includes a drive roller 766 and a driven roller 767 that are parallel to each other in the transport direction Y, and an endless belt 768 wound between the drive roller 766 and the driven roller 767. The belt 768 has a width of 8 rows (2 rows × 4 rows) or more of nozzle rows NL in the scanning direction X, and receives ink ejected from the nozzles 21 of the liquid injection portions 1A and 1B. It constitutes a liquid receiving unit 751a. In this case, the outer peripheral surface of the belt 768 becomes a liquid receiving surface 769 that receives ink.

The flushing unit 751 has a moisturizing liquid supply unit (not shown) capable of supplying a moisturizing liquid to the liquid receiving surface 769, and a liquid that scrapes off waste ink and the like adhering to the liquid receiving surface 769 in a moisturized state on the lower side of the belt 768. A scraping portion (not shown) is provided, and waste ink received on the liquid receiving surface 769 is removed from the belt 768 by the liquid scraping portion. Therefore, the orbital movement of the belt 768 updates the receiving range of the liquid receiving surface 769 facing the nozzle 21.

The cap unit 752 has two cap portions 752a capable of forming a closed space surrounding the liquid injection surface 20a (see FIG. 3), which is an opening region in which the nozzle 21 opens in contact with the two liquid injection portions 1A and 1B, respectively. Have. Each cap portion 752a is powered by the capping motor 755 to move between a contact position capable of contacting the liquid injection portion 1 and a retracted position away from the liquid injection portion 1. Each cap portion 752a includes one suction cap 770 and four moisturizing caps 771. Each moisturizing cap 771 suppresses drying of the nozzle 21 by contacting the liquid injection unit 1 and performing capping to form a closed space surrounding two rows of nozzle rows NL (see FIG. 3).

The suction cap 770 is connected to the suction pump 773 via a tube 772. Then, by driving the suction pump 773 in a state where the suction cap 770 is in contact with the liquid injection unit 1 to form a closed space, the thickening ink is applied from the nozzle 21 due to the action of the negative pressure generated in the suction cap 770. So-called suction cleaning is performed in which bubbles and bubbles are sucked together with the ink and discharged.

Such suction cleaning is performed for each of the two rows of nozzle rows NL for the liquid injection portions 1A and 1B. When the suction cleaning is performed, the ink droplets discharged from the nozzle 21 adhere to the liquid injection unit 1. Therefore, after the suction cleaning is executed, wiping with the wiping member 750a is performed in order to remove the adhered droplets and the like. It is preferable to do so. Further, when the wiping member 750a wipes, foreign matter or air bubbles adhering to the liquid injection unit 1 may be pushed into the nozzle 21 to destroy the meniscus or cause a discharge failure. Therefore, it is preferable to perform flushing after the wiping is performed to discharge the foreign matter mixed in the nozzle 21 and to prepare the ink meniscus in the nozzle 21.

<About the configuration of the fluid injection device>
Next, the configuration of the fluid injection device 775 will be described in detail.
As shown in FIG. 10, the fluid injection device 775 is configured to be capable of injecting at least one of air (gas) and a second liquid (cleaning liquid) into the liquid injection unit 1. Then, the fluid injection device 775 can inject a mixed fluid in which air and the second liquid are mixed by injecting the air and the second liquid together.

The second liquid is preferably the same as the main solvent of the ink used. In the present embodiment, since the water-based resin ink in which the solvent of the ink is water is adopted, pure water is used as the second liquid. For example, when the solvent of the ink is a solvent, the ink is used as the second liquid. It is preferable to use the same solvent as above. Further, as the second liquid, a liquid containing a preservative in pure water may be used.

The preservative contained in the second liquid is preferably the same as the preservative contained in the ink. For example, an aromatic halogen compound (for example, Preventol CMK), methylene dithiocyanate, and a halogen-containing nitrogen-sulfur compound. , 1,2-Benz isothiazolin-3-one (eg, PROXEL GXL) and the like. When PROXEL is used as the preservative from the viewpoint of difficulty in foaming, the content with respect to the second liquid is preferably 0.05% by mass or less.

The fluid injection device 775 includes an injection unit 777, and the injection unit 777 includes a fluid injection nozzle 778 having an injection port 778j capable of injecting a mixed fluid. The fluid injection nozzle 778 is arranged so as to inject the mixed fluid in the injection direction F (for example, upward perpendicular to the liquid injection surface a). The fluid injection nozzle 778 includes a liquid injection nozzle 780 that injects a second liquid in the injection direction F, and an annular gas injection nozzle 781 that injects air in the injection direction F and surrounds the liquid injection nozzle 780. And have.

That is, both the liquid injection nozzle 780 and the gas injection nozzle 781 are open in the injection direction F. Considering that the ink adheres and solidifies, the opening diameter of the liquid injection nozzle 780 is preferably sufficiently larger than the opening diameter of the nozzle 21 of the liquid injection unit 1, and is preferably 0.4 mm or more, for example. In the present embodiment, the opening diameter of the liquid injection nozzle 780 is set to 1.1 mm.

Further, as the fluid injection nozzle 778 of the present embodiment, a so-called external mixing type in which the mixing portion KA in which the second liquid and air are mixed is located outside the fluid injection nozzle 778 is adopted. Therefore, the mixing unit KA is composed of a predetermined space adjacent to the opening of the liquid injection nozzle 780 and the opening of the gas injection nozzle 781. A gas supply pipe 783 forming a gas flow path 783a for supplying air from the air pump 782 is connected to the fluid injection nozzle 778. The gas flow path 783a communicates with the gas injection nozzle 781.

A pressure adjusting valve 784 for adjusting the pressure of the air supplied from the air pump 782 is provided at an intermediate position of the gas supply pipe 783. In the fluid injection device 775 of the present embodiment, the pressure of the air supplied from the air pump 782 to the fluid injection nozzle 778 is set to be 200 kPa or more. An air filter 785 for removing dust and the like in the air supplied to the fluid injection nozzle 778 is provided at a position between the pressure adjusting valve 784 and the fluid injection nozzle 778 in the gas supply pipe 783.

Further, the fluid injection nozzle 778 is connected to a liquid supply pipe 788 that forms a liquid flow path 788a for supplying the second liquid stored in the storage tank 787 as an example of the liquid storage unit. The liquid flow path 788a communicates with the liquid injection nozzle 780. At the upper end of the storage tank 787, an atmospheric opening pipe 789 that opens the liquid storage space SK in the storage tank 787 to the atmosphere is provided, and the atmospheric opening pipe 789 is provided with a first solenoid valve 790 as an example of an on-off valve. There is.

Therefore, when the first solenoid valve 790 is opened, the liquid storage space SK is in a communicating state with the atmosphere via the atmosphere opening pipe 789, while when the first solenoid valve 790 is closed, the liquid storage space SK is in communication. Becomes a non-communication state that does not communicate with the atmosphere. That is, the first solenoid valve 790 is configured to be able to switch the liquid storage space SK between a communicating state and a non-communicating state by opening and closing.

Further, the storage tank 787 is connected to a cleaning liquid cartridge 791 that houses the second liquid and is detachably attached to the printer main body 11a (see FIG. 1) via a supply pipe 792. A liquid supply pump 793 for supplying the second liquid in the cleaning liquid cartridge 791 to the storage tank 787 is provided at an intermediate position of the supply pipe 792. A second solenoid valve 794 for opening and closing the supply pipe 792 is provided at a position between the liquid supply pump 793 and the storage tank 787 in the supply pipe 792.

As shown in FIGS. 11 and 12, the injection unit 777 includes a base member 800 having a substantially rectangular box shape with a bottom, a support member 801 arranged in the base member 800 to support the fluid injection nozzle 778, and the base member 800. It is provided with a rectangular tubular case 802 that is arranged inside and houses a fluid injection nozzle 778 and a support member 801. The fluid injection nozzle 778 is fixed to the support member 801 and the support member 801 and the case 802 are configured to be individually reciprocating in the base member 800 along the transport direction Y.

As shown in FIG. 11, the injection unit 777 includes a cleaning motor 803, a transmission mechanism 804 that transmits the driving force of the cleaning motor 803 to the support member 801 and a side plate 805 erected at the end on the printing area PA side. It has. Then, the support member 801 is reciprocated along the transport direction Y together with the fluid injection nozzle 778 by transmitting the driving force of the cleaning motor 803 via the transmission mechanism 804. In this case, the case 802 is reciprocated along the transport direction Y together with the support member 801 when pressed from the inside by the support member 801.

A cover member 806 as an example of a mating member that closes the upper end opening of the case 802 is attached to the case 802. A rectangular through hole 807 extending in the transport direction Y is formed at a position on the upper surface of the cover member 806 that overlaps a part of the moving region of the fluid injection nozzle 778 in the gravity direction Z. A rectangular frame-shaped lip portion 808 surrounding the through hole 807 is provided on the upper surface of the cover member 806. A guide portion (not shown) for guiding the case 802 when the case 802 reciprocates along the transport direction Y is provided on the surface of the side plate 805 on the case 802 side.

As shown in FIG. 12, the guide portion (not shown) has two rows of nozzle rows NL in which the case 802 rises at a position corresponding to the liquid injection portions 1A and 1B, and the lip portion 808 is located close to each other. The case 802 is guided so as to come into contact with the liquid injection unit 1 in the enclosed state.

In the present embodiment, the distance between the fluid injection nozzle 778 and the liquid injection unit 1 in the gravity direction Z is set to about 5 mm, and the medium ST and the liquid injection surface supported by the support base 712 shown in FIG. It is longer than the distance from 20a (about 1 mm).

<About the electrical configuration of the liquid injection device>
Next, the electrical configuration of the liquid injection device 7 will be described.
As shown in FIG. 13, the liquid injection device 7 includes a control unit 810 that collectively controls the liquid injection device 7. The control unit 810 is electrically connected to the linear encoder 811. The linear encoder 811 has a tape-shaped code plate provided on the back side of the carriage 723 shown in FIG. 1 so as to extend along the guide shaft 722, and a slit having a constant pitch fixed to the carriage 723 and drilled in the code plate. It is equipped with a sensor that detects the light transmitted through the carriage.

The control unit 810 inputs a number of pulses proportional to the movement amount of the printing unit 720 shown in FIG. 1 from the linear encoder 811, and the printing unit 720 transfers the number of the input pulses from the home position HP (see FIG. 2). The position of the printing unit 720 in the scanning direction X is grasped by adding when leaving and subtracting when approaching the home position HP.

A rotary encoder 812 is electrically connected to the control unit 810. The rotary encoder 812 includes a disk-shaped code plate attached to the output shaft of the cleaning motor 803, and a sensor that detects light transmitted through slits of a constant pitch formed in the code plate.

The control unit 810 inputs a number of pulses proportional to the movement amount of the support member 801 from the rotary encoder 812, and when the support member 801 leaves the standby position (position shown in FIG. 15), the number of the input pulses is set. The position of the support member 801 (fluid injection nozzle 778) in the transport direction Y is grasped by adding and subtracting when approaching the standby position.

The control unit 810 is electrically connected to the actuator 130 via the drive circuit 813 to drive and control the actuator 130. The control unit 810 grasps the clogging of each nozzle 21 based on the cycle of the residual vibration of the diaphragm 50 driven by the actuator 130.

The control unit 810 is electrically connected to the cleaning motor 803, the carriage motor 748, the transport motor 749, the wiping motor 753, the flushing motor 754, and the capping motor 755 via the motor drive circuits 814,815,816,817,818,819, respectively. It is connected to the. Then, the control unit 810 drives and controls the motors 803,748,749,753,754,755, respectively.

The control unit 810 is electrically connected to the suction pump 773, the air pump 782, and the liquid supply pump 793, respectively, via the pump drive circuits 820, 821, and 822, respectively. Then, the control unit 810 drives and controls the pumps 773, 782, and 793, respectively. The control unit 810 is electrically connected to the first solenoid valve 790 and the second solenoid valve 794, respectively, via the valve drive circuits 823 and 824. Then, the control unit 810 drives and controls the solenoid valves 790 and 794, respectively.

<Maintenance operation by maintenance device>
Next, the operation of the liquid injection device 7 will be described with particular attention to the maintenance operation performed by the maintenance device 710 on the liquid injection unit 1.

When print data is input to the control unit 810 through an external device or the like, the control unit 810 drives the carriage motor 748 based on the print data, and the liquid injection units 1A and 1B are in the process of the printing unit 720 moving in the scanning direction X. Ink droplets are ejected from each nozzle 21 of the above toward the surface of the medium ST. Then, the ejected ink droplets land on the surface of the medium ST, so that an image or the like is printed on the surface of the medium ST.

During printing of the medium ST, at a predetermined time (for example, every predetermined time within a range of 10 to 30 seconds) for the purpose of preventing thickening of the ink in the nozzle 21 that does not eject ink droplets among all the nozzles 21. The printing unit 720 moves to the receiving region FA and performs flushing by ejecting ink droplets from all the nozzles 21.

Further, when the predetermined suction cleaning condition is satisfied, the control unit 810 controls the carriage motor 748 and moves the printing unit 720 to the home position HP to perform suction cleaning. In the suction cleaning, the suction pump 773 is driven in a state where the suction cap 770 is brought into contact with the liquid injection unit 1 so as to surround the nozzle row NL to form a closed space, and a negative pressure is applied to the suction cap 770. Then, a predetermined amount of ink is sucked from the nozzle 21 to remove thickening ink, air bubbles and the like.

After the suction cleaning is completed, the control unit 810 moves the printing unit 720 to the wiping area WA and causes the wiping member 750a to perform wiping to wipe the liquid injection unit 1, so that the liquid injection unit is discharged from the nozzle 21 and is discharged from the liquid injection unit. Remove the droplets and the like adhering to 1. Further, after the wiping is executed, the control unit 810 moves the printing unit 720 to the receiving region FA and flushes the liquid receiving unit 751a to prepare the meniscus in the nozzle 21.

After that, the control unit 810 detects the clogging of each nozzle 21 based on the cycle of the residual vibration of the diaphragm 50 driven by the actuator 130. Here, the clogging of each nozzle 21 is detected after the suction cleaning is completed, in particular, the ink contains a resin ink containing a synthetic resin that is cured by heating or a UV ink that is cured by UV (ultraviolet) irradiation. This is because when used, the nozzle 21 may not be cleared of clogging even if suction cleaning is performed. The term "clogging" as used herein means not only a state in which the ink in the nozzle 21 is solidified and clogged, but also a state in which the ink is solidified so as to form a film on the meniscus of the nozzle 21, or the inside of the nozzle 21 and the pressure generating chamber 12 are clogged. , And the state in which the ink cannot be normally ejected (jetted) from the nozzle 21 due to the thickening of the ink in the nozzle communication passage 16.

If the print job is waiting when all the nozzles 21 are not clogged, the control unit 810 moves the print unit 720 to the print area PA to print the medium ST. On the other hand, when the clogged nozzles 21 are detected among all the nozzles 21, the control unit 810 moves the printing unit 720 to the non-printing area LA on the side opposite to the home position HP side in the scanning direction X. By cleaning the inside of the clogged nozzle 21 with the fluid injection device 775, the nozzle cleaning for clearing the clogging of the nozzle 21 is performed.

Then, when the fluid injection device 775 performs nozzle cleaning, these positions are aligned so that the clogged nozzle 21 and the fluid injection nozzle 778 face each other in the direction of gravity Z. In this case, the alignment of the scanning direction X (the direction orthogonal to the extending direction of the nozzle row NL) between the clogged nozzle 21 and the fluid injection nozzle 778 is performed by moving the printing unit 720, and the clogged nozzle is used. The alignment of the transport direction Y (the direction in which the nozzle row NL extends) between the 21 and the fluid injection nozzle 778 is performed by moving the fluid injection nozzle 778.

Specifically, when the clogged nozzle 21 is located in the liquid injection section 1A, the lip section 808 is clogged after the scanning direction X of the printing section 720 is aligned as shown in FIG. The case 802 is moved via the support member 801 so as to come into contact with the liquid injection surface 20a while surrounding the nozzle row NL including the nozzle 21. Subsequently, the fluid injection nozzle 778 is moved via the support member 801 so that the liquid injection nozzle 780 of the fluid injection nozzle 778 faces the clogged nozzle 21, and the position of the fluid injection nozzle 778 in the transport direction Y is aligned.

At this time, in the normal state before the mixed fluid is injected from the fluid injection nozzle 778, the first solenoid valve 790 is opened so that the liquid storage space SK communicates with the atmosphere and the second solenoid valve 794 communicates with the atmosphere. The valve is closed.

In this state, as shown in FIG. 10, the height H of the gas-liquid interface KK of the second liquid in the liquid flow path 788a is -100 to − when the height of the tip of the fluid injection nozzle 778 is set to 0. It is preferably set to be 1000 mm. In the present embodiment, the height H when the height of the tip of the fluid injection nozzle 778 is 0 is set to be −150 mm.

Then, in the state shown in FIGS. 10 and 12, when the air pump 782 is driven to supply air to the fluid injection nozzle 778, air is injected from the gas injection nozzle 781. The second liquid in the liquid flow path 788a is sucked up by the negative pressure generated by the injection of the air and is injected from the liquid injection nozzle 780. As a result, air and the second liquid are mixed in the mixing unit KA to generate a mixed fluid, and the mixed fluid is injected into a part of the liquid injection surface 20a including the clogged nozzle 21.

This mixed fluid is in the form of droplets smaller than the opening of the nozzle 21 (for example, when the opening of the nozzle is circular and the shape of the droplet is spherical, the diameter is 20 μm or less, which is smaller than the opening diameter of the nozzle). A large number of second liquids (the droplets of the second liquid having a small diameter are called small droplets DS, see FIG. 16) are contained, and the injection speed of the mixed fluid from the fluid injection nozzle 778 at this time is 40 m or more per second. It is set to be. The kinetic energy of the small droplet DS can destroy the film-like ink solidified at the gas-liquid interface to the extent that the energy transmitted to the gas-liquid interface in the nozzle 21 cannot be destroyed by the ink ejection operation or flushing operation during printing. It is preferably equal to or higher than the kinetic energy.

That is, the product of the mass of the small droplet DS of the second liquid ejected from the injection port 778j by the fluid injection device 775 toward the nozzle 21 and the square of the flight velocity of the small droplet DS at the opening position of the nozzle 21 is , It is set to be larger than the product of the mass of the ink droplet ejected from the opening of the nozzle 21 and the square of the flight speed of the ink droplet.

Further, when the mixed fluid containing the small droplet DS of the fluid injection device 775 is injected into the clogged nozzle 21 (the opening region where the nozzle 21 opens), the ink in the pressure generating chamber 12 communicating with the clogged nozzle 21 is discharged. It is preferable to perform the operation in a state of being pressurized by the vibration of the vibrating plate 50 driven by the actuator 130 corresponding to the pressure generating chamber 12. Then, when the mixed fluid is injected from the fluid injection nozzle 778 into the nozzle 21 in which the mixed fluid is clogged, a droplet-like second liquid smaller than the opening of the nozzle 21 in the mixed fluid enters the nozzle 21 through the opening of the nozzle 21. And collide with the clogged part.

That is, the second liquid in the form of droplets smaller than the opening of the nozzle 21 collides with the ink solidified in the nozzle 21. The impact of the second liquid on the solidified ink destroys the solidified ink, and the clogging of the nozzle 21 is cleared. At this time, since the ink in the pressure generating chamber 12 communicating with the nozzle 21 in which the clogging is cleared is pressurized, the mixed fluid entering the nozzle 21 is a liquid via the pressure generating chamber 12. It is suppressed from entering the inside of the injection unit 1A.

When stopping the injection of the mixed fluid from the fluid injection nozzle 778, first, the first solenoid valve 790 is closed while the mixed fluid is being injected from the fluid injection nozzle 778 to accommodate the liquid. The SK is switched from a communication state that communicates with the atmosphere to a non-communication state that does not communicate with the atmosphere. Then, since the liquid storage space SK becomes a negative pressure, the second liquid injected from the liquid injection nozzle 780 is drawn into the liquid flow path 788a by the action of this negative pressure.

As a result, the gas-liquid interface KK of the second liquid (water head surface of the storage tank 787) in the liquid flow path 788a is located on the lower side (storage tank 787 side) of the mixing portion KA. Then, when the air pump 782 is stopped, air is no longer injected from the gas injection nozzle 781. In this case, the air pump 782 is stopped in a state where the gas-liquid interface KK of the second liquid in the liquid flow path 788a is located below the mixing portion KA, so that the second liquid in the liquid flow path 788a is the mixing portion. It is suppressed from entering the gas injection nozzle 781 beyond KA.

Further, in this case, even after the supply of air from the air pump 782 to the gas injection nozzle 781 via the liquid flow path 788a is stopped, the closed state of the first solenoid valve 790 is maintained, and the liquid storage space SK is in a non-communication state. Is maintained. The unnecessary second liquid after cleaning the nozzle 21 and the unnecessary ink washed away from the nozzle 21 flow down from the inside of the case 802 into the base member 800, and the waste liquid port of the base member 800 (not shown). Is collected in a waste liquid tank (not shown).

Further, when the clogged nozzle 21 is also present in the liquid injection portion 1B, as shown in FIG. 14, the lip portion 808 is clogged in the liquid injection portion 1B as in the case of the liquid injection portion 1A. The case 802 is moved via the support member 801 so as to come into contact with the liquid injection surface 20a while surrounding the nozzle row NL including the nozzle 21. Then, as in the case of the liquid injection unit 1A, the mixed fluid is injected into the clogged nozzle 21 of the liquid injection unit 1B with the first solenoid valve 790 opened to eliminate the clogging of the nozzle 21. do.

The mixed fluid may be injected from the fluid injection nozzle 778 to the liquid injection units 1A and 1B including the clogged nozzle 21 a plurality of times at time intervals. In this case, the time interval may or may not be constant. By doing so, even if the mixed fluid injected into the liquid injection portions 1A and 1B becomes foamy and closes the opening of the nozzle 21, the bubbles that close the opening of the nozzle 21 while the injection of the mixed fluid is stopped. The mixed fluid returns to a droplet shape. For this reason, the droplets in the mixed fluid that are first injected into the liquid injection portions 1A and 1B to form bubbles and close the opening of the nozzle 21 are then injected into the liquid injection portions 1A and 1B. It is possible to prevent the entry into the nozzle 21 from being blocked. If pure water containing no preservative is used as the second liquid, such foaming is suppressed.

Then, as shown in FIG. 15, after the cleaning of the clogged nozzles 21 of the liquid injection units 1A and 1B by the fluid injection device 775 is completed, the support member is in a state where the mixed fluid is injected from the fluid injection nozzle 778. The 801 is moved to the standby position so that the fluid injection nozzle 778 faces a position on the upper wall of the cover member 806 that does not correspond to the through hole 807. At this time, a slight gap is formed between the fluid injection nozzle 778 and the upper wall of the cover member 806.

Then, the air injected from the annular gas injection nozzle 781 surrounding the liquid injection nozzle 780 collides with the upper wall of the cover member 806 and flows along the upper wall, so that the air is injected from the annular gas injection nozzle 781. The pressure inside the air, that is, above the liquid injection nozzle 780, rises. Then, the second liquid in the liquid flow path 788a is pressed downward (the storage tank 787 side) by the increased pressure on the upper side of the liquid injection nozzle 780. That is, the gas-liquid interface KK of the second liquid in the liquid flow path 788a is pushed down far below the mixing portion KA.

If the air pump 782 is stopped in this state, air will not be injected from the gas injection nozzle 781. In this case, the air pump 782 is stopped in a state where the gas-liquid interface KK of the second liquid in the liquid flow path 788a is located below the mixing portion KA, so that the second liquid in the liquid flow path 788a is the mixing portion. It is suppressed from entering the gas injection nozzle 781 beyond KA.

After that, the printing unit 720 is moved to the home position HP side, and suction cleaning and flushing for ejecting ink from the openings of the nozzles 21 of the liquid injection units 1A and 1B are performed to enter the liquid injection units 1A and 1B. Residual second liquid, air bubbles, etc. are removed. The suction cleaning and flushing at this time can be performed with a small amount of ink (consumption). This is because the injection of the mixed fluid into the clogged nozzle 21 was performed in a state where the ink in the pressure generating chamber 12 communicating with the clogged nozzle 21 was pressurized as described above, so that the mixed fluid was pressurized. This is because the entry (backflow) into the liquid injection portions 1A and 1B via the generation chamber 12 was suppressed.

(Second Embodiment)
Next, a second embodiment of the liquid injection device will be described with reference to the drawings.
In the second embodiment, those having the same reference numerals as those in the first embodiment have the same configurations as those in the first embodiment, so the description thereof will be omitted. In the following, the description will be focused on the points different from those in the first embodiment. conduct.

As shown in FIG. 16, the fluid injection device 775D included in the liquid injection device of the present embodiment is configured so that the direction in which the fluid injection nozzle 778 injects the fluid can be changed. Here, the position of the fluid injection nozzle 778 when injecting the fluid in the first injection direction S1 substantially orthogonal to the opening surface (liquid injection surface 20a) through which the nozzle 21 opens is referred to as the first position P1. Further, the position of the fluid injection nozzle 778 when injecting the fluid in the second injection direction S2 diagonally intersecting the liquid injection surface 20a is called the second position P2, and is parallel to the liquid injection surface 20a. The position of the fluid injection nozzle 778 when injecting the fluid in the three injection directions S3 is referred to as the third position P3.

Further, in the fluid injection device 775D, the liquid tank 832 is connected to the liquid supply pipe 788 that supplies the second liquid to the fluid injection nozzle 778 via the supply pipe 831. The surfactant is stored in the liquid tank 832. Further, in the supply pipe 831, the liquid tank 832 and the liquid supply pipe 788 are in a communicating state when the supply pipe 831 is opened, while the liquid tank 832 and the liquid supply pipe 788 are in a non-communication state when the supply pipe 831 is in the closed state. An on-off valve 833 is provided. When the mixed fluid is injected from the fluid injection nozzle 778 when the on-off valve 833 is in the open state, the surfactant in the liquid tank 832 is sucked out by the negative pressure generated by the injection and mixed with the second liquid. Will be done. That is, in the fluid injection device 775D, by opening the on-off valve 833, the fluid injection nozzle 778 injects a mixed fluid of a gas, a second liquid, and a surfactant.

Further, the liquid injection device of the present embodiment includes a fluid injection device 775B in addition to the fluid injection device 775D. The fluid injection device 775B includes an air pump 782B, a gas supply pipe 783B whose downstream end is connected to the air pump 782B, a storage tank 787B, a liquid supply pipe 788B whose downstream end is connected to the storage tank 787B, and a gas supply pipe 783B. And a fluid injection nozzle 778B to which the upstream end of the liquid supply pipe 788B is connected, respectively. Then, a third liquid containing a liquid repellent component is stored in the storage tank 787B of the fluid injection device 775B.

The fluid injection device 775B may be capable of injecting a fluid containing a third liquid containing a liquid repellent component, and may adopt the same configuration as the fluid injection device 775 of the first embodiment, or one of the configurations. The part may be changed. The fluid injection device 775B is arranged in, for example, the non-printing area LA or the non-printing area RA, and the fluid injection nozzle 778B is capable of injecting the fluid in the second injection direction S2 diagonally intersecting the liquid injection surface 20a. Is placed in the second position P2.

<Maintenance operation by fluid injection device>
Next, the operation of the liquid injection device will be described with particular attention to the maintenance operation performed by the maintenance device 710 on the liquid injection unit 1.

The fluid injection device 775D selectively selects nozzle cleaning in the first mode, liquid injection surface cleaning in the second mode, gas spraying in the third mode, foam adhesion in the fourth mode, or fluid injection in the sixth mode, depending on the purpose. To run. Further, the fluid injection device 775B executes the liquid repellent treatment in the fifth mode at a predetermined timing.

As shown in FIG. 17, in the nozzle cleaning in the first mode, as described in detail in the first embodiment, the opening region (liquid injection surface) where the nozzle 21 opens for the purpose of clearing the clogging of the nozzle 21. For 20a), the fluid injection nozzle 778 performs a first fluid injection for injecting a fluid containing a small droplet DS of the second liquid smaller than the opening of the nozzle 21. That is, in the first mode, the fluid injection nozzle 778 is arranged in the first position P1 and the on-off valve 833 is closed, and the second liquid and gas mixed fluid is targeted at the specific nozzle 21 in which clogging has occurred. A short time injection is performed in the first injection direction S1 at high speed and high pressure.

Next, in the liquid injection surface cleaning in the second mode, the fluid injection nozzle 778 has a smaller droplet diameter than the small droplet DS with respect to the liquid injection surface 20a of the liquid injection unit 1 for the purpose of cleaning the liquid injection surface 20a. A second fluid injection is performed to inject a fluid containing a large droplet DL of a second liquid having a large size (when the droplet is spherical). Compared with the ink droplet DM having the maximum diameter (when the droplet is spherical) ejected from the nozzle 21, the small droplet DS has a smaller droplet diameter than the ink droplet DM, and the large droplet DL has an ink droplet. The droplet diameter is larger than DM.

In the second mode, the fluid injection nozzle 778 is arranged in the second position P2, the on-off valve 833 is closed, and the mixed fluid of the second liquid and gas is targeted at the portion of the liquid injection surface 20a where the nozzle 21 does not open. The injection is performed in the second injection direction S2 for a predetermined time at a lower speed and lower pressure than the first mode.

That is, the direction in which the fluid injection device 775D injects the fluid from the injection port 778j in the first fluid injection is the first injection direction S1, and the direction in which the fluid injection device 775D injects the fluid from the injection port 778j in the second fluid injection is the first. Assuming that the two injection directions S2, the intersection angle of the second injection direction S2 with respect to the liquid injection surface 20a is preferably smaller than the intersection angle of the first injection direction S1 with respect to the liquid injection surface 20a. In this way, the fluid injected by the fluid injection nozzle 778 is less likely to enter the nozzle 21, so that the meniscus of the ink formed in the nozzle 21 is less likely to break.

If the meniscus of the ink formed in the nozzle 21 is broken or disturbed, the meniscus can be prepared by flushing or the like, but it takes time to prepare the meniscus or the ink is consumed. Therefore, it is desirable that the meniscus is not destroyed or disturbed by the maintenance operation.

In the second fluid injection (liquid injection surface cleaning), in the second injection direction S2 in which the fluid injection device 775D injects the fluid from the injection port 778j, the distance from the injection port 778j to the liquid injection surface 20a is set to perform the first fluid injection. If it is made longer than when it is performed, the flight speed of the droplet when it reaches the liquid injection surface 20a can be reduced. In this way, even if the fluid injected by the fluid injection nozzle 778 enters the nozzle 21, the meniscus of the ink formed in the nozzle 21 is not easily broken, which is preferable.

Here, when deposits such as ink adhering to the liquid injection surface 20a are solidified, when the wiping member 750a wipes the liquid injection surface 20a, the solidified material slides into contact with the liquid injection surface 20a. There is. The liquid injection surface 20a is often subjected to a liquid repellent treatment for enhancing the liquid repellent property, such as applying a liquid repellent agent to form a liquid repellent film in order to suppress adhesion of ink droplets. Therefore, when the wiping member 750a wipes the liquid injection surface 20a to which the solidified material is attached, the solidified material is dragged and the liquid repellent film is damaged, so that the liquid repellent effect may be deteriorated. In that respect, in the maintenance of the second mode performed by the fluid injection device 775D, the liquid injection surface 20a is cleaned with the second liquid, so that foreign matter (ink) adhering to the liquid injection surface 20a without damaging the liquid repellent film. And dust) can be removed.

Further, when the liquid injection surface 20a is wiped with the wiping member 750a, foreign matter or air bubbles adhering to the liquid injection surface 20a may be pushed into the nozzle 21, resulting in poor injection of droplets. On the other hand, in the case of injecting the second liquid onto the liquid injection surface 20a for cleaning, foreign matter is not pushed into the nozzle 21, which is preferable.

Wiping may be performed by the wiping member 750a in a state where the second liquid injected by the fluid injection nozzle 778 by the first fluid injection or the like is attached to the liquid injection surface 20a. That is, as a maintenance operation, the fluid injection device 775D injects fluid into the opening region (liquid injection surface 20a) where the nozzle 21 opens in the liquid injection unit 1 to adhere the second liquid, and then the second liquid. The opening area is wiped by the wiping member 750a that has been moistened by contact with. According to this configuration, the dirt adhering to the liquid injection surface 20a dissolves in the second liquid and is easily removed, and the frictional resistance of the wiping member 750a to the liquid injection surface 20a is reduced, so that the liquid repellent film is less likely to be scratched. Become. At the time of this wiping, it is sufficient that the second liquid adheres to the liquid injection unit 1 or the wiping member 750a. A second liquid or a mixed fluid containing the second liquid may be injected toward the member 750a.

In this case, the fluid injection nozzle 778 may inject a fluid containing the second liquid into a non-opening region (for example, a portion of the cover head 400) that does not include the opening region (liquid injection surface 20a). That is, as a maintenance operation, after the fluid injection device 775D injects a fluid such as a second fluid injection into the non-open area to adhere the second liquid to the liquid injection unit 1, the wiping member 750a is the second fluid. The wiping member 750a that comes into contact with the wet non-opening region and is further wet with the second fluid wipes the open region by the contact. In this way, if the fluid is injected while avoiding the opening region where the nozzle 21 opens, the destruction of the meniscus by the fluid injected by the fluid injection nozzle 778 in order to wet the liquid injection unit 1 is suppressed, which is preferable. ..

Next, in the gas spraying in the third mode, the liquid injection surface 20a of the liquid injection unit 1 is subjected to the purpose of removing foreign substances (particularly, unsolidified ink droplets, dust, etc.) adhering to the liquid injection surface 20a. , The fluid injection nozzle 778 injects only gas. That is, since the fluid injection device 775D can selectively inject three types of gas, a second liquid, or a mixed fluid of a gas and a second liquid from the injection port 778j, only the gas is injected to inject the liquid. The foreign matter adhering to the surface 20a is blown off.

Assuming that the direction in which the fluid injection device 775D injects gas from the injection port 778j in the third mode is the gas injection direction (third injection direction S3), the angle θ of the third injection direction S3 with respect to the liquid injection surface 20a is 0 ° ≦. It is preferable that θ <90 °. Further, when the angle θ of the third injection direction S3 with respect to the liquid injection surface 20a is small (for example, θ = 0 °) and the possibility that the injected gas disturbs the meniscus of the nozzle 21 is small, the gas is injected at high speed and high pressure. However, it is preferable because the efficiency of removing foreign substances is high.

That is, if the injection direction of the gas from the fluid injection nozzle 778 is the third injection direction S3, the gas injected by the fluid injection nozzle 778 does not easily enter the nozzle 21, so that the meniscus of the ink formed in the nozzle 21 is formed. It is preferable because it is hard to break. Then, in the third mode, since the object does not slide on the liquid injection surface 20a, foreign matter (ink, dust, etc.) adhering to the liquid injection surface 20a is removed by blowing air without damaging the liquid repellent film. It becomes possible.

Further, since the removal of foreign matter by gas injection can be performed in a shorter time than wiping performed by moving the wiping member 750a, for example, the liquid injection unit 1 is periodically removed during the printing operation in the printing area PA. It is possible to perform maintenance such as moving to the print area LA and blowing off ink droplets and the like adhering to the liquid injection surface 20a with a gas to remove them. In addition, in the case of gas injection, it is possible to remove foreign matter adhering to a portion where the wiping member 750a cannot contact (for example, a step portion or a gap portion between the cover head 400 and the liquid injection surface 20a).

Further, when the gas injection direction (third injection direction S3) is set along the direction in which the nozzle row NL extends, the nozzles 21 in the adjacent row in which the blown ink (first liquid) injects ink of another color. It is preferable because it is possible to avoid entering and mixing colors.

Next, in the fourth mode of foam adhesion, the fluid injection nozzle 778 moves the gas, the second liquid, and the surfactant in the second injection direction S2 for the purpose of adhering the foamy second liquid to the liquid injection unit 1. Inject the mixed fluid of. In the fourth mode, the fluid injection nozzle 778 is arranged in the first position P1 and the on-off valve 833 is opened, the surfactant is mixed with the second liquid injected from the fluid injection nozzle 778, and the surfactant is mixed in the first injection direction S1. A second liquid is foamed by causing the injected fluid to collide with the liquid injection surface 20a or a non-opening region (for example, a portion of the cover head 400) for a predetermined time. In the fourth mode, foaming of the liquid is promoted by mixing the surfactant with the second liquid injected from the fluid injection nozzle 778.

The mixing ratio of the second liquid and the surfactant can be adjusted by changing the head difference between the second liquid in the storage tank 787 and the surfactant in the liquid tank 832. Further, in the fourth mode, as in the second mode, when a fluid containing a large droplet DL of the second liquid having a smaller minimum droplet diameter than the small droplet DS is injected at a lower speed and a lower pressure than in the first mode, the nozzle It is preferable because it does not easily disturb the meniscus of 21. Further, in the fourth mode, the second liquid can be efficiently foamed by continuing the injection of the fluid containing the second liquid for a longer time than the fluid injection as the nozzle cleaning in the first mode. ..

Even in the fluid injection device 775 of the first embodiment, when a liquid containing a preservative in pure water is used as the second liquid, the liquid injection unit 1 is affected by the action of the components contained in the preservative. The second liquid that collides with the water may become foamy. Therefore, in such a case, it is not necessary to mix the surfactant with the second liquid to be jetted.

Then, as shown in FIG. 18, after the fluid injection device 775D attaches the foam BU (foam-like second liquid) to the liquid injection unit 1, the wiping member 750a or the wiping member 750B is attached to the foam-like second liquid. The wiping member 750B wipes the area to be wiped. That is, the fluid injection device 775D functions as a liquid adhesion device that adheres a foamy second liquid to the liquid injection unit 1. In this way, the frictional resistance when the wiping member 750a is in sliding contact with the liquid injection surface 20a is reduced by the foam BU, and the liquid repellent film is less likely to be scratched, which is preferable. In the present embodiment, the elastically deformable plate-shaped member is exemplified as the wiping member 750B for wiping, but the same applies to the wiping member 750a made of the cloth sheet shown in the first embodiment. The action can be obtained.

Assuming that the portion wiped by the wiping member 750B of the liquid injection portion 1 is the wiped region, the wiped region includes an opening region (liquid injection surface 20a) in which the nozzle 21 opens in the liquid injection portion 1 and an outside of the opening region including the liquid injection portion 1. Includes a non-open area (cover head 400) located in. That is, it is preferable that the wiping member 750B wipes not only the liquid injection surface 20a but also the outer cover head 400 portion. The region to which the fluid injection device 775D attaches the foam BU (foam-like second liquid) before wiping may be an open region, a non-open region, or both regions.

By the way, as shown in FIG. 19, when capping is performed by contacting the moisturizing cap 771 and the suction cap 770 with the cover head 400 which is a non-opening region, when the caps 770 and 771 come into contact with the liquid injection unit 1. In addition, the liquid adhering to the liquid injection unit 1 may collect in the annular contact region where the caps 770 and 771 come into contact with each other.

Then, after the caps 770 and 771 are separated from the liquid injection unit 1 by releasing the capping, contact marks (also referred to as lip marks) of the caps 770 and 771 may remain in the contact area of the liquid injection unit 1. Therefore, when the wiping area includes the contact area where the caps 770 and 771 come into contact during the execution of capping, the fluid injection device 775D attaches the foam BU (foam-like second liquid) to the contact area, and then wiping is performed. , It is preferable because the contact mark can be removed.

In addition, as shown in FIG. 19, in a state where the fluid injection device 775D adheres the droplet or bubble BU of the second liquid to the liquid injection unit 1 by injecting the mixed fluid in the first, second or fourth mode. The moisturizing cap 771 may come into contact with the liquid injection unit 1 to perform capping so that the attached second liquid is contained in the closed space. In this way, the humidity of the closed space can be kept high by the second liquid contained in the closed space formed by the moisturizing cap 771, so that the moisturizing effect of the nozzle 21 can be enhanced and the moisturizing time can be lengthened. It becomes possible to do.

In this case, the fluid injection device 775D functions as a liquid adhesion device that adheres the second liquid to the liquid injection unit 1. In the fluid injection device 775D, by mixing a gas with the second liquid and injecting it, it is possible to reduce the droplet diameter of the second liquid and increase the flight speed and injection pressure of the droplets. can. Therefore, when the fluid injection device 775D is used for adhering the second liquid to the liquid injection unit 1, it is not necessary to mix the gas with the fluid to be injected, and the second liquid is made into droplets and flies. You do not have to let it.

Here, if the fluid injected by the fluid injection device 775D vigorously collides with the liquid injection unit 1 at an angle close to a right angle, the fluid collides with the liquid injection unit 1 and easily scatters to the surroundings. In that respect, by reducing the intersection angle between the fluid injection direction F and the liquid injection unit 1, scattering when the fluid comes into contact with the liquid injection unit 1 is suppressed, and the second liquid is efficiently injected into the liquid injection unit 1. Can be attached to. Therefore, in order to attach the second liquid droplets to the liquid injection unit 1, it is preferable to inject the fluid in the second injection direction S2. On the other hand, in order to foam the second liquid in the liquid injection unit 1, it is preferable to inject the mixed fluid in the first injection direction S1 with the second liquid containing gas.

As shown in FIG. 19, when the second liquid is attached to the liquid injection unit 1 prior to capping by contacting the moisturizing cap 771 with the cover head 400 which is a non-opening region, the cover head 400 is attached. It is preferable that the fluid injection device 775D injects the second liquid toward the nozzle 21 because the injected second liquid does not damage the meniscus of the nozzle 21. On the other hand, if the second liquid is adhered to the liquid injection surface 20a by the injection of the fluid injection device 775D, the second liquid can be present at a position closer to the nozzle 21, so that the moisturizing effect can be enhanced.

Further, after the first fluid injection or the like is executed by the fluid injection device 775D, the wiping member 750a or the wiping member 750B wipes to clean the liquid injection unit 1, and then the second fluid injection or the like of the fluid injection device 775D is performed. It is preferable that the moisturizing cap 771 caps when the second liquid is attached to the liquid injection unit 1 by the execution. That is, by performing wiping in a state of being moistened with the second liquid to remove foreign matter adhering to the liquid injection unit 1, and then performing capping, foreign matter adhering to the liquid injection unit 1 during capping is performed. Can be suppressed from sticking.

As shown in FIG. 20, when a foamy second liquid is attached to a position close to the nozzle 21, a film Me of the second liquid is formed on the meniscus surface Sf of the nozzle 21 after the foam BU disappears. The film Me functions as an anti-drying film. Therefore, when capping is performed for a long time or when the environmental temperature is high, it is preferable to perform capping with the foam-like second liquid adhered to the liquid injection surface 20a. In addition, when capping for a long time, if the foam BU that has been foamed by mixing the surfactant with the second liquid is attached, the foam BU is less likely to crack due to the action of the surfactant. 2 The liquid foam BU can be allowed to stay near the nozzle 21 for a longer period of time.

Further, as shown in FIG. 19, if the absorbent material 774 capable of absorbing and holding the liquid is housed in the moisturizing cap 771, the droplets of the second liquid and the foam BU adhering to the liquid injection unit 1 are contained in the moisturizing cap. Even when it runs down the lip portion or the side wall of 771, the second liquid that has run down can be absorbed by the absorbent material 774 and held.

Further, at the time of capping, a portion (for example, of the cover head 400) surrounded by the moisturizing cap 771 of the liquid injection unit 1 so that the second liquid adhering to the liquid injection unit 1 is held by the liquid injection unit 1 for as long as possible. Grooves or recesses may be formed in the portion, etc.). By holding the second liquid adhering to the liquid injection unit 1 at a position close to the nozzle 21, the nozzle 21 can be efficiently moisturized.

Further, the liquid injection surface 20a preferably has high liquid repellency in order to suppress adhesion and solidification of ink droplets, but the liquid repellency of the cover head 400 or the like located around the liquid injection surface 20a is made lower than that of the liquid injection surface 20a. Then, the cover head 400 can hold the second liquid for moisturizing while suppressing the adhesion of the droplets to the liquid injection surface 20a.

In addition, in order to enhance the moisturizing effect, capping may be performed after the ink (waste ink) is put in the moisturizing cap 771 by flushing or the like. Also in this case, the evaporation or volatilization of the dispersion medium or solvent (water or the like, for example) contained in the ink or the like suppresses the drying of the nozzle 21 that opens in the moisturizing cap 771. In addition, the liquid injection unit 1 may be separately provided with a roller or the like for adhering a liquid for moisturizing.

Further, when capping is performed by contacting the suction cap 770 with the cover head 400, it is preferable that the liquid adhering to the liquid injection unit 1 after suction cleaning quickly moves to the suction cap 770 side. Therefore, it is preferable to set the lip portion of the suction cap 770 that comes into contact with the cover head 400 so that the liquid repellency is lower than that of the cover head 400.

Next, in the liquid repellent treatment in the fifth mode, when the liquid repellent film is damaged, the fluid injection device 775B performs the liquid injection surface 20a as a maintenance operation for recovering the liquid repellent performance of the liquid injection surface 20a. On the other hand, a fluid containing a third liquid droplet having a smaller minimum droplet diameter than the small droplet DS is injected in the second injection direction S2. At this time, by injecting the third liquid together with the gas, the droplets of the third liquid can be diffused over a wide range. After the droplets of the third liquid are attached to the liquid injection surface 20a, wiping may be performed to uniformly spread the third liquid over the entire area of the liquid injection surface 20a.

Next, the fluid injection maintenance in the sixth mode is performed by the injection step of injecting the fluid into the liquid injection unit 1 through the opening of the nozzle 21 of one of the plurality of nozzles 21 and the pressure of the fluid injected by the injection step. The liquid injection unit 1 includes a discharge step of discharging the fluid containing the ink through the openings of the other nozzles 21 of the plurality of nozzles 21.

That is, the liquid injection unit 1 communicates with the common liquid chamber 100 and the common liquid chamber 100 capable of storing the first liquid (ink) supplied via the liquid supply path 727, and is supplied from the common liquid chamber 100. It has a plurality of nozzles 21 capable of ejecting one liquid onto a medium. Then, the fluid injection device 775D injects the fluid into the liquid injection unit 1 through the opening of the nozzle 21 of one of the plurality of nozzles 21, and the fluid containing the first liquid (ink) is injected from the plurality of nozzles 21. Perform fluid injection maintenance for discharging through the openings of the other nozzles 21. In this respect, the fluid injection device 775D functions as a fluid injection device capable of injecting at least one of a gas and a second liquid into the liquid injection unit 1 through the opening of the nozzle 21.

In the injection step, as shown in FIG. 21, a nozzle row NL is formed by using the fluid injection nozzle 778 of the fluid injection device 775D in order to discharge the foreign matter mixed in the common liquid chamber 100 of the liquid injection unit 1. The fluid is injected through the openings of some of the nozzles 21 among the plurality of nozzles 21. For example, the fluid injection device 775D arranges the fluid injection nozzle 778 in the first position P1 and closes the on-off valve 833, so that the second liquid has a diameter smaller than the opening diameter of the nozzle 21 toward the opening of the nozzle 21. The fluid containing the small droplet DS is injected in the first injection direction S1 at high speed and high pressure for a longer time than in the first mode.

That is, the fluid injection device 775D functioning as a fluid injection device has an injection port 778j capable of injecting a second liquid, and in a state where the injection port 778j is separated from the liquid injection unit 1, the fluid is injected from the injection port 778j. By doing so, the fluid is injected into the opening of at least one of the plurality of nozzles 21.

The fluid injected from the nozzles 21 flows through the common liquid chamber 100 communicating with the plurality of nozzles 21, and pushes out the ink in the common liquid chamber 100 together with the foreign matter from the other nozzles 21 (discharging step). Examples of foreign matter mixed in the common liquid chamber 100 include air bubbles and fragments of a film (solidified ink) that has been destroyed by the nozzle cleaning in the first mode and has entered the inner part of the nozzle 21. Can be mentioned.

Since the sixth mode has the same injection conditions as the first mode except that the injection time is longer than that of the first mode, the injection time of the fluid injection for cleaning the nozzles of the first mode is the same as that of the first mode. By continuing the above, the fluid injection in the first mode and the sixth mode can be continuously executed. In this case, the fluid injection device (fluid injection device 775D) is one of the plurality of nozzles 21 by injecting a fluid containing a small droplet DS of the second liquid having a diameter smaller than the opening diameter of the nozzle 21. The fluid is injected into the liquid injection unit 1 through the opening of the nozzle 21.

During the injection process, on the upstream side of the common liquid chamber 100, there is a differential pressure valve 731 (one-way valve) that opens when the pressure in the liquid chamber becomes a predetermined pressure (for example, 1 kPa) lower than the pressure in the space outside the liquid chamber. Since the fluid injected from the nozzle 21 does not flow back to the upstream side, foreign matter in the common liquid chamber 100 can be efficiently discharged from the other nozzle 21 together with the first liquid in the discharge process. That is, when the liquid supply path 727 is provided with a differential pressure valve 731 that functions as a supply regulating unit capable of regulating the flow of the liquid, the fluid injection device 775D is in a state where the differential pressure valve 731 regulates the flow of the liquid upstream. It is preferable to perform fluid injection maintenance. For example, when an on-off valve that can be arbitrarily opened and closed is provided instead of the differential pressure valve 731, it is preferable to perform fluid injection maintenance with the on-off valve closed.

Further, in the liquid supply path 727, since there is a filter 216 between the common liquid chamber 100 and the differential pressure valve 731, even if the fluid is injected into the nozzle 21, foreign matter (such as a fragment of a film) is generated by the flow. 2 The inflow to the upstream flow path 502 (see FIG. 8) is suppressed.

In fluid injection maintenance, when the fluid injection device 775D injects a fluid into one nozzle 21, an actuator 130 corresponding to a nozzle 21 different from the nozzle 21 injecting the fluid may be driven. In the nozzle 21 into which no fluid is injected, even if the pressure in the common liquid chamber 100 fluctuates slightly, ink does not leak from the nozzle 21 as long as the pressure fluctuation is within the meniscus pressure resistance range. Even in such a configuration, by driving the actuator 130 to pressurize the pressure generating chamber 12 with which the nozzle 21 communicates, ink is pushed out from the nozzle 21, so that the meniscus is destroyed and the liquid flows out from the nozzle 21. be able to.

Here, foreign matter such as filtered solids may accumulate and adhere to the upstream surface of the filter 216. In this case, in the fluid injection maintenance, the liquid injected from the downstream side flows back from the second liquid reservoir 503a to the first liquid reservoir 502a, so that the foreign matter adhering to the upstream surface of the filter 216 is separated from the filter 216. It is expected to be done.

As a result, deposits on the filter 216 that could not be removed by the flow to the downstream side such as suction cleaning can be removed by suction cleaning performed after the fluid injection maintenance operation. When a part of the wall surface forming the liquid chamber of the differential pressure valve 731 has flexibility, even if the liquid flow to the upstream side is regulated by the differential pressure valve 731, it fluctuates due to the deflection displacement of the wall surface. Since the amount of liquid to be collected flows from the second liquid reservoir 503a to the first liquid reservoir 502a, there is a high possibility that the deposits will separate from the filter 216.

In the sixth mode, a nozzle on one end side (left end side in FIG. 21) in the longitudinal direction of the common liquid chamber 100 is used to generate a flow in the common liquid chamber 100 in one direction indicated by an arrow in FIG. It is preferable to inject the fluid from 21 so that the liquid is discharged from the nozzle 21 on the other end side (right end side in FIG. 21).

In the sixth mode, as long as the foreign matter can be discharged into the liquid injection unit 1, any of a gas, a second liquid, or a mixed fluid of a gas and a second liquid may be injected. When any of the fluids is injected, a fluid different from the ink (first liquid) is mixed in the liquid injection unit 1, so that the suction cap 770 is used after the maintenance of the sixth mode. It is preferable to perform suction cleaning using the suction pump 773 and fill the nozzle 21 with the first liquid to discharge the mixed fluid from the liquid injection unit 1. That is, after the fluid injection device 775D performs fluid injection maintenance while the supply regulation unit (differential pressure valve 731) regulates the flow of liquid, the differential pressure valve 731 is released from the regulation and is on the upstream side of the liquid supply path 727. Ink is supplied from the above to fill the first liquid up to the opening of the nozzle 21.

The maintenance operation of the liquid injection unit 1 including the second to sixth modes as described above may be performed by selecting an appropriate mode every time printing is performed for a predetermined time or every time a predetermined amount medium ST is conveyed. good. Alternatively, the state of the opening surface (liquid injection surface 20a) is detected by a sensor or the like, and if foreign matter is attached to the liquid injection surface 20a, for example, the second mode is selected, and the mode is set according to the detection status. You may choose to perform maintenance.

According to the above embodiment, the following effects can be obtained.
(1) In the first mode, the fluid injection device 775D injects the first fluid into the opening region to introduce a small droplet DS of the second liquid smaller than the opening of the nozzle 21 into the nozzle 21. , Nozzle cleaning, which is maintenance for clearing the clogging of the nozzle 21, can be performed. On the other hand, in the second fluid injection in the second mode performed by the fluid injection device 775D on the liquid injection unit 1, the droplet DL of the second liquid having the smallest droplet larger than the small droplet DS is ejected, so that the same liquid. The drop DL does not easily enter the nozzle 21. Therefore, in the second mode, the meniscus formed in the nozzle 21 is prevented from being destroyed by the droplet DL of the second liquid entering the unclogging nozzle 21. Therefore, maintenance of the liquid injection unit 1 having the nozzle 21 capable of injecting the liquid can be efficiently performed.

(2) In the second mode, the fluid injection device 775D injects the second fluid into the opening region to prevent the droplet DL of the second liquid from destroying the meniscus in the nozzle 21 while opening. The area can be cleaned. Further, when the fluid injection device 775D injects the second fluid into the opening region, the second liquid adheres to the opening region of the liquid injection unit 1. Therefore, after that, the wiping member 750B wipes the opening region, so that the cleaning member 750B is moistened with the second liquid adhering to the liquid injection unit 1 and the opening region is maintained (wiping). As a result, the frictional resistance becomes smaller than when the wiping member 750B wipes the opening region in a dry state, so that the load applied to the opening region by the wiping operation can be reduced. Further, by moistening the fixed substance stuck to the opening region with the second liquid, the fixed substance is dissolved in the second liquid, so that the foreign matter stuck to the opening region can be efficiently removed by wiping with the wiping member 750B. can.

(3) In the second mode, the fluid injection device 775D injects the second fluid into the non-open area, thereby suppressing the droplet DL of the second liquid from destroying the meniscus in the nozzle 21. Cleaning of non-open areas can be performed. Further, the wiping member 750B can be wetted with the second liquid by contacting the wiping member 750B with the non-opening region after the second fluid injection. Therefore, by wiping the opening region after that, the wiping member 750B can remove the foreign matter adhering to the opening region while reducing the load applied to the opening region as compared with the case where the opening region is wiped in a dry state. can.

(4) By using pure water as the main component of the second liquid, even if the second liquid enters the nozzle 21, deterioration due to mixing with the second liquid of the first liquid in the nozzle 21 is suppressed. can do. Further, when the pure water which is the main component contains a preservative, it is possible to suppress the spoilage of the second liquid held in the fluid injection device 775, 775D.

(5) The fluid injection device 775B injects a fluid containing a third liquid containing a liquid repellent component to adhere the third liquid to the liquid injection unit 1 and improve the liquid repellent property of the liquid injection unit 1. be able to. Then, by improving the liquid repellency of the liquid injection unit 1, the liquid injection unit 1 injects the first liquid from the nozzle 21 toward the medium ST, so that a minute mist of the first liquid is unintentionally generated. However, even when the mist adheres to the liquid injection unit 1, it is possible to suppress the adhesion of the first liquid to the liquid injection unit 1.

(6) Since the distance from the injection port 778j to the liquid injection unit 1 when the fluid injection device 775D performs the second fluid injection in the second mode is longer than that when the first fluid injection is performed in the first mode, the first The flight speed of the droplet of the second liquid that reaches the liquid injection unit 1 by the two-fluid injection becomes relatively slow. This makes it difficult for the second liquid to enter the nozzle 21, and even if it does, the impact when it collides with the meniscus is reduced, so that the destruction of the meniscus can be suppressed. Further, if the flight speed of the droplets is high, there is a risk that the droplets will vigorously collide with the liquid injection unit 1 and scatter to the surroundings. However, by slowing the flight speed of the droplets, the droplets come into contact with the liquid injection unit 1. The second liquid can be efficiently adhered to the liquid injection unit 1 by suppressing the scattering of the liquid.

(7) Since the intersection angle of the second injection direction S2 with respect to the opening surface (liquid injection surface 20a) through which the nozzle 21 opens is smaller than the intersection angle of the first injection direction S1 with respect to the opening surface, the nozzle 21 is injected by the second fluid injection. The second liquid droplet DL does not easily enter the nozzle 21. Therefore, in the second mode, the destruction of the meniscus of the nozzle 21 due to the second fluid injection can be suppressed.

(8) Since the angle of the gas injection direction (third injection direction S3) with respect to the opening surface (liquid injection surface 20a) through which the nozzle 21 opens is 0 ° ≤ θ <90 °, the gas injected from the injection port 778j It is suppressed that the meniscus is disturbed by entering the nozzle 21. Further, the fluid injection device 775D injects the gas into the liquid injection unit 1 with the angle with respect to the opening surface reduced, thereby causing the gas to flow along the opening surface and blowing off the deposits adhering to the liquid injection unit 1. Can be removed efficiently.

(9) The kinetic energy of the droplet ejected from the injection port 778j or the nozzle 21 is obtained by the product of the mass of the droplet and the square of the flight velocity of the droplet at a predetermined position. If the kinetic energy of the first liquid droplet ejected from the nozzle 21 by the liquid injection unit 1 is large, even if the nozzle 21 is slightly clogged, the clogging is caused by the energy of the droplet. It can be resolved. On the other hand, when the nozzle 21 is severely clogged, the clogging cannot be cleared by the energy for ejecting the droplets of the first liquid from the nozzle 21. In that respect, in the first mode, the kinetic energy at the opening position of the nozzle 21 of the small droplet DS ejected from the injection port 778j toward the nozzle 21 by the fluid injection device 775D causes the droplet of the first liquid from the nozzle 21 to be ejected. Greater than the energy to inject. Therefore, when the small droplet DS of the second liquid ejected by the fluid injection device 775D enters the nozzle 21 to eliminate the clogging of the nozzle 21 that cannot be eliminated by the injection operation of ejecting the droplet of the first liquid from the opening of the nozzle 21. It can be eliminated by the kinetic energy of.

(10) When the fluid injection device 775D injects the first fluid into the opening region of the liquid injection unit 1, the actuator 130 is driven in the liquid injection unit 1 to enter the pressure generating chamber 12 communicating with the nozzle 21. By pressurizing, the pressure in the nozzle 21 increases. Then, the small droplet DS of the second liquid injected by the fluid injection device 775D becomes difficult to enter the inner inner side of the nozzle 21. Therefore, when a film is stretched on the opening of the nozzle 21 in the liquid injection section 1, the small droplet DS of the second liquid ejected by the fluid injection device 775D is made to collide with the film stretched on the opening of the nozzle 21 to form the film. While it is destroyed, foreign matter such as the destroyed film is suppressed from entering the nozzle 21. Therefore, even when the droplets are ejected from the outside of the nozzle 21 to clear the clogging, it is possible to suppress the mixing of the droplets and foreign matter into the nozzle 21.

(11) Since the liquid adhering device (fluid injection device 775D) attaches the second liquid to the liquid injection unit 1 prior to the cap 771 capping, when the cap 771 caps to form a closed space. , A second liquid can be present near the nozzle 21. Therefore, the nozzle 21 can be efficiently moisturized by the second liquid that evaporates near the nozzle 21.

(12) Since the liquid adhesion device (fluid injection device 775D) can adhere the second liquid to the liquid injection unit 1 by injecting the second liquid from the injection port 778j, the second liquid can be attached to the liquid injection unit 1 at a position away from the liquid injection unit 1. A fluid injection device 775D can be arranged.

(13) By mixing a gas with the second liquid ejected by the liquid adhesion device (fluid injection device 775D), the second liquid can be made into finer droplets and flown. Then, by injecting such minute droplets, the second liquid can be uniformly adhered to a predetermined region of the liquid injection unit 1.

(14) If the second liquid is adhered to the opening region where the nozzle 21 opens, the second liquid may enter the nozzle 21 and be mixed with the first liquid. In that respect, if the second liquid is adhered to the non-opening region of the liquid injection unit 1 that does not include the opening region, the second liquid can be prevented from entering the nozzle 21.

(15) The liquid adhering device (fluid injection device 775D) injects the small droplet DS of the second liquid into the opening region to introduce the small droplet DS into the nozzle 21 and clog the nozzle 21. Nozzle cleaning, which is maintenance to eliminate the problem, can be performed. At this time, since the second liquid that did not enter the nozzle 21 adheres to the opening region, the second liquid is consumed for moisturizing by capping so that the adhered second liquid is contained in the closed space. It is efficient because the nozzle 21 can be moisturized without separately performing an operation for adhering the second liquid to the liquid injection unit 1.

(16) By performing wiping after executing the first fluid injection by the liquid adhering device (fluid injection device 775D), the second liquid adhering to the opening region by the first fluid injection and the foreign matter adhering to the opening region are removed. Since it can be removed, the liquid injection unit 1 can be efficiently maintained. Further, when the liquid injection unit 1 can be cleaned by executing the second fluid injection by the fluid injection device 775D, and when the second liquid adheres to the liquid injection unit 1 by executing the second fluid injection. By performing capping, it is not necessary to separately perform an operation for adhering the second liquid to the liquid injection unit 1. Further, in the first fluid injection, since the small droplet DS is introduced into the nozzle 21 to clear the clogging, the meniscus in the nozzle 21 may be in a disordered state after the execution of the first fluid injection. Highly sex. On the other hand, in the second fluid injection, since the droplet having the smallest droplet larger than the small droplet DS is ejected, the possibility that the second liquid enters the nozzle 21 and destroys the meniscus is small. Therefore, if capping is performed after the execution of the second fluid injection, it is possible to prevent the nozzle 21 from being left in a disordered state of the meniscus, as compared with the case where the capping is performed after the execution of the first fluid injection.

(17) The liquid adhering device (fluid injection device 775D) attaches the second liquid to the wiped area wiped by the wiping member 750B, thereby dissolving the foreign matter adhering to the wiped area in the second liquid and efficiently removing the foreign matter. Can be removed. Further, by making the second liquid foamy, the frictional resistance when the wiping member 750B comes into contact with the area to be wiped is reduced, so that when the wiping member 750B wipes the liquid injection unit 1, the liquid injection unit 1 is wiped. The load applied to 1 can be reduced.

(18) In the fluid injection device 775D, by mixing the gas with the second liquid, the fluid injected from the injection port 778j can contain the gas. Therefore, in the fourth mode, the second liquid in contact with the wiped area. 2 The liquid can be efficiently foamed.

(19) In the nozzle cleaning in the first mode, the small droplet DS can be introduced into the nozzle 21 to eliminate the clogging. Then, in the nozzle cleaning, by shortening the injection duration for injecting the fluid, it is possible to prevent the second liquid from forming bubbles, and to prevent the small droplet DS from entering the nozzle 21 due to the bubbles. On the other hand, in the fourth mode, the second liquid can be foamed by lengthening the injection duration for injecting the fluid, so that the liquid adhering device (fluid injection device 775D) for cleaning the nozzle is used. 2 It can also be used as a device for foaming a liquid.

(20) The wiped area to be wiped includes an opening area where the nozzle 21 opens in the liquid injection unit 1, and the wiping member 750B wipes the opening area, so that foreign matter adheres to the vicinity of the opening of the nozzle 21. Can be removed.

(21) When the second liquid enters the nozzle 21, the meniscus of the nozzle 21 may be disturbed, or the first liquid and the second liquid in the nozzle 21 may be mixed. In that respect, when the liquid adhering device (fluid injection device 775D) adheres the foamy second liquid to the non-opening region located outside the opening region, the mixing of the second liquid into the nozzle 21 is suppressed. be able to.

(22) When the caps 770 and 771 come into contact with the liquid injection unit 1, the liquid adhering to the liquid injection unit 1 gathers at the contact portion with the caps 770 and 771, so that the caps 770 and 771 inject liquid. After leaving the portion 1, contact marks of the caps 770 and 771 may remain on the liquid injection portion 1. In that respect, the liquid adhering device (fluid injection device 775D) adheres the foamy second liquid to the region including the contact region where the caps 770 and 771 come into contact, and the wiping member 750B wipes the region to inject the liquid. The contact marks of the caps 770 and 771 attached to the portion 1 can be efficiently removed.

(23) The spoilage of the second liquid can be suitably suppressed by the effect of the preservative containing at least one of the aromatic halogen compound, methylene dithiocyanate and the halogen-containing nitrogen-sulfur compound contained in the second liquid. ..

(24) In fluid injection maintenance, the fluid injection device (fluid injection device 775D) injects fluid into the liquid injection unit 1 through the opening of one nozzle 21, so that the plurality of nozzles 21 and those nozzles 21 communicate with each other. Foreign matter in the common liquid chamber 100 can be discharged from the opening of another nozzle 21 together with the first liquid in the common liquid chamber 100. Therefore, the foreign matter existing in the liquid injection unit 1 having the plurality of nozzles 21 can be discharged.

(25) When the fluid injection maintenance is executed, the supply regulation unit (differential pressure valve 731) regulates the flow of the liquid, so that the fluid injected from the nozzle 21 by the fluid injection device (fluid injection device 775D) is moved to the upstream side. Since it does not flow, the injected fluid can be efficiently discharged from the other nozzle 21.

(26) After the fluid injection maintenance, in the process of supplying the first liquid from the upstream side of the liquid supply path 727 and filling the first liquid to the opening of the nozzle 21, the fluid injection device replaces the filled first liquid. Since the second liquid injected by the 775D from the nozzle 21 is discharged, the foreign matter in the common liquid chamber 100 can be discharged together with the second liquid. Further, by filling the first liquid up to the opening of the nozzle 21 in this way, it is possible to prepare for the next liquid injection operation.

(27) In the fluid injection maintenance, the filter 216 located between the supply regulation unit (differential pressure valve 731) and the common liquid chamber 100 causes foreign matter to follow the flow of the fluid injected from the nozzle 21 to the differential pressure valve 731. It is possible to suppress the flow toward the direction. Further, by applying pressure from the downstream side of the filter 216 to the fluid injected from the nozzle 21, solid matter and the like accumulated on the upstream side of the filter 216 can be peeled off from the filter 216.

(28) When the fluid injection maintenance is executed, the fluid injection device (fluid injection device 775D) drives an actuator 130 corresponding to another nozzle 21 different from the nozzle 21 in which the fluid is injected, thereby causing the fluid injection device to be transmitted from the other nozzle 21. Can promote the discharge of fluid.

(29) Since the injection port 778j for injecting the second liquid by the fluid injection device (fluid injection device 775D) is arranged at a position away from the liquid injection unit 1, the injection port of the first liquid to be injected by the liquid injection unit 1 Adhesion to 778j can be suppressed.

(30) When the fluid injection device (fluid injection device 775D) injects a fluid containing a small droplet DS of the second liquid smaller than the opening of the nozzle 21, the energy of the collision of the small droplet DS causes the nozzle 21 to eject the fluid. The clogging can be eliminated. Then, when the foreign matter that has caused the clogging of the nozzle 21 enters the common liquid chamber 100 inside the nozzle 21, the foreign matter is discharged by the fluid injection maintenance performed by the fluid injection device (fluid injection device 775D). can do. Therefore, since the device for clearing the clogging of the nozzle 21 is also used by the (fluid injection device 775D), the configuration of the liquid injection device 7 is more than the case where the device for clearing the clogging of the nozzle 21 is separately provided. It can be simplified.

In addition, each of the above-described embodiments may be changed as in the modification shown below. Further, each of the above-described embodiments and the following modified examples can be used in any combination.
As in the first modification shown in FIG. 22, the liquid injection unit 1 (1C) having two liquid injection heads 3 (3A, 3B) in which ink is supplied from one differential pressure valve 731 through the supply flow path 732 In some cases, maintenance of the liquid injection heads 3A and 3B may be performed by the fluid injection devices 775, 775B and 775D. Further, in the liquid injection unit 1C, fluid injection maintenance can be performed in which the fluid is injected from all the nozzles 21 of one liquid injection head 3A and the liquid is discharged from all the nozzles 21 of the other liquid injection head 3B.

In this case, the liquid may be injected using the liquid injection device 835 as shown in FIG. 22 for fluid injection maintenance. That is, the liquid injection device 835 connects the storage unit 836 that stores the liquid for injection, the cap 837 that can form a closed space in which the nozzle 21 of the liquid injection head 3 opens, and the storage unit 836 and the cap 837. It includes a flow path 838 and a supply pump 839 that pressurizes and supplies the liquid in the storage unit 836 toward the cap 837. Then, the cap 837 is brought into contact with, for example, the liquid injection head 3A to form a closed space, and the supply pump 839 is driven to pressurize and supply the liquid for injection into the closed space. Then, as shown by an arrow in FIG. 22, the pressurized liquid in the closed space enters through the opening of the nozzle 21, and the common liquid chamber 100 of the liquid injection head 3A, the supply flow path 732, and the other liquid injection head 3B The liquid flows through the common liquid chamber 100 of the above, and the liquid is discharged together with the foreign matter from the nozzle 21 of the liquid injection head 3B.

-As in the second modification shown in FIG. 23, instead of the external mixing type fluid injection nozzle 778, the second liquid supplied from the liquid flow path 788a and the air supplied from the gas flow path 783a are mixed. A so-called internal mixing type fluid injection nozzle 778B having a mixing unit KA for generating a mixed fluid may be used. In this case, the mixed fluid generated by the mixing unit KA is injected from the injection port 778j provided at the tip (upper end) of the fluid injection nozzle 778B.

-For the fluid injection in each mode in the second embodiment, the injection direction, injection speed, droplet diameter, and injection pressure can be arbitrarily changed. For example, the fluid injection device 775 similar to that of the first embodiment may be used to perform the fluid injection in each mode in the first injection direction S1.

-Before injecting the mixed fluid from the fluid injection nozzle 778 to the liquid injection portions 1A and 1B including the nozzle 21, the second liquid is injected to the liquid injection portions 1A and 1B including the nozzle 21. May be good. In this case, the liquid supply pump 793 may be used to inject the second liquid from the liquid injection nozzle 780, but a pump for injecting the second liquid from the liquid injection nozzle 780 is separately provided at an intermediate position of the liquid supply pipe 788. It is preferable to provide it. By doing so, the second liquid is first injected into the liquid injection portions 1A and 1B including the nozzle 21, and then air is mixed with the second liquid to inject the mixed fluid. , It is possible to suppress the injection of only air to the liquid injection units 1A and 1B including the nozzle 21. Therefore, it is possible to prevent the air injected into the liquid injection portions 1A and 1B including the nozzle 21 from entering the inside of the liquid injection portions 1A and 1B from the opening of the nozzle 21. Further, in this case, even when the injection of the mixed fluid to the liquid injection units 1A and 1B including the nozzle 21 is stopped, the injection of the air is stopped first, and then the injection of the second liquid is stopped. It is possible to prevent only air from being injected into the liquid injection units 1A and 1B including the nozzle 21.

A temperature sensor 711 (see FIG. 2) provided on the carriage 723 may be used to detect fluid injection defects in the fluid injection devices 775B and 775D. That is, a liquid or a fluid containing a liquid is injected from the fluid injection nozzle 778 of the fluid injection device 775, 775D or the fluid injection nozzle 778B of the fluid injection device 775B toward the temperature sensor 711, and the detection result of the temperature sensor 711 at that time. Based on the above, a fluid injection defect in the fluid injection devices 775B and 775D is detected.

Specifically, if a liquid is properly injected from the fluid injection nozzles 778 and 778B, the temperature sensor 711 is cooled by contacting the liquid with the temperature sensor 711, so that the temperature sensor 711 detects a decrease in temperature. By doing so, it is possible to detect that the liquid is properly injected from the fluid injection nozzles 778 and 778B. On the other hand, if the temperature of the temperature sensor 711 does not decrease even though the fluid injection devices 775 and 775D perform the injection operation, the liquid injection failure may occur due to clogging of the fluid injection nozzles 778 and 778B or running out of liquid. It is possible to determine that it has occurred.

A pressure pump for supplying the ink in the ink tank (not shown) to the storage unit 730 is provided, and the nozzle 21 is clogged during injection of the mixed fluid from the fluid injection nozzle 778 to the clogged nozzle 21. The pressurization of the ink in the communicating pressure generating chamber 12 may be performed by the pressurizing pump with the differential pressure valve 731 open.

-Before injecting the mixed fluid from the fluid injection nozzle 778 to the liquid injection portions 1A and 1B including the nozzle 21, the second liquid is injected into the region of the liquid injection portions 1A and 1B not including the nozzle 21. You may do so. Further, before injecting the mixed fluid from the fluid injection nozzle 778 to the liquid injection portions 1A and 1B including the nozzle 21, the fluid injection nozzle 778 injects the second liquid at a position not facing the liquid injection portions 1A and 1B. You may try to do it. Even in this way, it is possible to prevent only air from being injected into the liquid injection units 1A and 1B including the nozzle 21.

-The second liquid, which is the second liquid, may be composed of pure water only (pure water containing no preservative). In this way, when the second liquid is mixed with the ink in the nozzle 21, it is possible to prevent the second liquid from adversely affecting the ink.

-When injecting the mixed fluid into the clogged nozzle 21, the actuator 130 corresponding to the clogged nozzle 21 may be driven in the same manner as when the ink is ejected or flushed during printing. Even in this way, it is possible to prevent the mixed fluid from entering the clogged nozzle 21.

When injecting a mixed fluid into a clogged nozzle 21, the actuator 130 corresponding to the nozzle 21 other than the clogged nozzle 21 is driven to correspond to the nozzle 21 other than the clogged nozzle 21. The pressure generating chambers 12 to be generated may be pressurized respectively. By doing so, it is possible to prevent the mixed fluid from entering the nozzle 21 other than the clogged nozzle 21.

-The fluid injection device 775 may be arranged in the non-printing area RA.
A wiper for wiping the liquid injection surfaces 20a of the liquid injection portions 1A and 1B may be separately provided between the fluid injection device 775 in the non-printing area LA and the printing area PA. In this way, after the mixed fluid is injected into the liquid injection units 1A and 1B by the fluid injection device 775, the mixed fluid (second liquid) is before the printing unit 720 is moved to the home position HP side across the print area PA. ) Wet liquid injection surface 20a can be wiped off with the above wiper. Therefore, it is possible to prevent the mixed fluid (second liquid) adhering to the liquid injection surface 20a from dripping during the movement of the printing unit 720 in the printing area PA.

-Instead of the air pump 782, an air compressor of equipment such as a factory may be used. In this case, a three-way solenoid valve capable of opening the gas flow path 783a to the atmosphere is provided at a position between the pressure regulating valve 784 and the air filter 785 in the gas supply pipe 783, and the gas flow when the fluid injection device 775 is not used. Road 783a may be open to the atmosphere.

When the control unit 810 detects a nozzle 21 whose clogging is not cleared even if suction cleaning is performed a predetermined number of times based on the clogging detection history, the nozzle 21 whose clogging is not cleared temporarily is not used. Alternatively, so-called complementary printing may be performed by injecting ink with another normal nozzle 21 to perform printing. In this case, the nozzle 21 whose clogging is not cleared even if the suction cleaning is performed a predetermined number of times after the complementary printing may be cleaned by the fluid injection device 775, 775D to clear the clogging.

-The nozzle row NL (nozzle 21) that injects ink of a color (type) that is extremely infrequently used is when it is time to use it without performing usual maintenance (suction cleaning, flushing, wiping, etc.). The clogging may be cleared by cleaning with a fluid injection device 775, 775D. In this way, the consumption of ink of a color (type) that is extremely infrequently used in suction cleaning and flushing is reduced, so that the ink can be saved.

-During the injection of the mixed fluid from the fluid injection nozzle 778 to the clogged nozzle 21, it is not always necessary to pressurize the pressure generating chamber 12 communicating with the clogged nozzle 21.
The product of the mass of the second liquid droplet smaller than the opening of the nozzle 21 and the square of the flight speed of the droplet at the opening position of the nozzle 21 is not necessarily the mass of the ink droplet ejected from the opening of the nozzle 21. It does not need to be larger than the product of the square of the flight speed of the ink droplet.

-The liquid ejected by the liquid injection unit is not limited to ink, and may be, for example, a liquid material in which particles of a functional material are dispersed or mixed in the liquid. For example, recording is performed by injecting a liquid material containing materials such as electrode materials and coloring materials (pixel materials) used in the manufacture of liquid crystal displays, EL (electroluminescence) displays and surface emitting displays in the form of dispersion or dissolution. It may be configured.

-The medium is not limited to paper, but may be a plastic film, a thin plate material, or a cloth used for a printing device or the like.
Next, the ink (colored ink) as the first liquid will be described in detail below.

The ink used in the liquid injection device 7 contains a resin in composition and substantially does not contain glycerin having a boiling point of 290 ° C. under 1 atm. If the ink contains substantially glycerin, the dryness of the ink is significantly reduced. As a result, in various media, particularly ink non-absorbent or low-absorbent media, not only the shading unevenness of the image is conspicuous, but also the ink fixability cannot be obtained. Further, it is preferable that the ink substantially does not contain alkyl polyols (excluding the above-mentioned glycerin) having a boiling point of 280 ° C. or higher at 1 atm.

Here, "substantially not contained" in the present specification means that the content is not contained in an amount that sufficiently exerts the significance of addition. Quantitatively speaking, it is preferable that glycerin is not contained in an amount of 1.0% by mass or more, more preferably 0.5% by mass or more, and 0, based on the total mass (100% by mass) of the ink. . It is more preferably not contained in an amount of 1% by mass or more, further preferably not contained in an amount of 0.05% by mass or more, and particularly preferably not contained in an amount of 0.01% by mass or more. Most preferably, it does not contain 0.001% by mass or more of glycerin.

Next, the additives (components) contained or may be contained in the ink will be described.
[1. Color material]
The ink may contain a coloring material. The coloring material is selected from pigments and dyes.

[1-1. Pigment]
By using a pigment as a coloring material, the light resistance of the ink can be improved. As the pigment, either an inorganic pigment or an organic pigment can be used. The inorganic pigment is not particularly limited, and examples thereof include carbon black, iron oxide, titanium oxide, and silica oxide.

The organic pigment is not particularly limited, but for example, quinacridone pigment, quinacridone quinone pigment, dioxazine pigment, phthalocyanine pigment, anthrapyrimidine pigment, anthanthrone pigment, indanslon pigment, flavanthron pigment, Examples thereof include perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments. .. Specific examples of the organic pigment include the following.

Examples of the pigment used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15:34, 16, 18, 22, 60, 65, 66, C.I. I. Bat blue 4, 60 can be mentioned. Above all, C.I. I. Pigment Blue 15: 3 or 15: 4 is preferred.

Pigments used in magenta ink include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 , 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, 254, 264, C.I. I. Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50. Above all, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, and C.I. I. One or more selected from the group consisting of Pigment Violet 19 is preferable.

Examples of the pigment used in the yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180, 185, 213 and the like. Above all, C.I. I. One or more selected from the group consisting of Pigment Yellow 74, 155, and 213 is preferable.

Examples of pigments used for inks of colors other than the above, such as green ink and orange ink, include conventionally known pigments.
The average particle size of the pigment is preferably 250 nm or less because clogging in the nozzle 21 can be suppressed and the ejection stability is further improved. The average particle size in the present specification is based on the volume. As a measuring method, for example, it can be measured by a particle size distribution measuring device based on a laser diffraction / scattering method. Examples of the particle size distribution measuring device include a particle size distribution meter based on a dynamic light scattering method (for example, Microtrack UPA manufactured by Nikkiso Co., Ltd.).

[1-2. dye]
A dye can be used as the coloring material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. The content of the coloring material is preferably 0.4 to 12% by mass, more preferably 2% by mass or more and 5% by mass or less, based on the total mass (100% by mass) of the ink.

[2. resin]
The ink contains a resin. When the ink contains a resin, a resin film is formed on the medium, and as a result, the ink is sufficiently fixed on the medium, and the effect of mainly improving the scratch resistance of the image is exhibited. Therefore, the resin emulsion is preferably a thermoplastic resin. The thermal deformation temperature of the resin is preferably 40 ° C. or higher, preferably 60 ° C. or higher, because it is unlikely to cause clogging of the nozzle 21 and has an advantageous effect of imparting abrasion resistance to the medium. More preferred.

Here, the "thermal deformation temperature" in the present specification is a temperature value represented by a glass transition temperature (Tg) or a minimum film forming temperature (MFT). That is, "the thermal deformation temperature is 40 ° C. or higher" means that either Tg or MFT may be 40 ° C. or higher. Since it is easier to grasp the superiority or inferiority of the redispersibility of the resin in MFT than in Tg, the thermal deformation temperature is preferably a temperature value represented by MFT. If the ink has excellent redispersibility of the resin, the ink does not stick to the ink, so that the nozzle 21 is less likely to be clogged.

Specific examples of the thermoplastic resin are not particularly limited, but are poly (meth) acrylic acid ester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polycyanoacrylate, polyacrylamide, poly (meth) acrylic acid and the like. (Meta) acrylic polymers, polyethylene, polypropylene, polybutene, polyisobutylene, and polystyrene, and their copolymers, and polyolefin-based polymers such as petroleum resin, kumaron-inden resin, and terpene resin, polyvinyl acetate. Or its copolymer, polyvinyl alcohol, polyvinyl acetal, and vinyl acetate-based or vinyl alcohol-based polymer such as polyvinyl ether, polyvinyl chloride or its copolymer, polyvinylidene chloride, fluororesin, and halogen-containing such as fluororubber. System polymers, polyvinylcarbazole, polyvinylpyrrolidone or copolymers thereof, nitrogen-containing vinyl polymers such as polyvinylpyridine, and polyvinylimidazole, polybutadienes or copolymers thereof, polychloroprenes, and dienes such as polyisoprene (butyl rubber). Examples include polymers and other ring-opening polymerized resins, condensation polymerized resins, and natural polymer resins.

The content of the resin is preferably 1 to 30% by mass, more preferably 1 to 5% by mass, based on the total mass (100% by mass) of the ink. When the content is within the above range, the glossiness and scratch resistance of the formed topcoat image can be further improved. Examples of the resin that may be contained in the ink include a resin dispersant, a resin emulsion, and wax.

[2-1. Resin emulsion]
The ink may include a resin emulsion. When the medium is heated, the resin emulsion preferably forms a resin film together with wax (emulsion), thereby exhibiting the effect of sufficiently fixing the ink on the medium and improving the scratch resistance of the image. When the medium is printed with an ink containing a resin emulsion due to the above effects, the ink has excellent abrasion resistance particularly on an ink non-absorbent or low-absorbent medium.

Further, the resin emulsion that functions as a binder is contained in the ink in an emulsion state. By containing a resin that functions as a binder in the ink in an emulsion state, it is easy to adjust the viscosity of the ink to an appropriate range in the inkjet recording method, and it is possible to improve the storage stability and ejection stability of the ink.

Resin emulsions include, but are not limited to, (meth) acrylic acid, (meth) acrylic acid ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, and vinylpyrrolidone. , Vinylpyridine, vinylcarbazole, vinylimidazole, and vinylidene chloride homopolymers or copolymers, fluororesins, and natural resins. Among them, either a methacrylic acid-based resin or a styrene-methacrylic acid copolymer-based resin is preferable, and any of an acrylic-based resin and a styrene-acrylic acid copolymer-based resin is more preferable, and a styrene-acrylic acid copolymer-based resin is more preferable. Even more preferable. The above-mentioned copolymer may be in any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

The average particle size of the resin emulsion is preferably in the range of 5 nm to 400 nm, more preferably in the range of 20 nm to 300 nm, in order to further improve the storage stability and ejection stability of the ink. Among the resins, the content of the resin emulsion is preferably in the range of 0.5 to 7% by mass with respect to the total mass (100% by mass) of the ink. When the content is within the above range, the solid content concentration can be lowered, so that the discharge stability can be further improved.

[2-2. wax]
The ink may contain wax. When the ink contains wax, the fixability of the ink on the non-ink-absorbing and low-absorbing medium becomes more excellent. The wax is more preferably an emulsion type. The wax is not limited to the following, and examples thereof include polyethylene wax, paraffin wax, and polyolefin wax, and among them, polyethylene wax described later is preferable. In addition, in this specification, a "wax" mainly means a thing in which solid wax particles are dispersed in water by using the surfactant which will be described later.

When the ink contains polyethylene wax, the scratch resistance of the ink can be improved. The average particle size of the polyethylene wax is preferably in the range of 5 nm to 400 nm, preferably in the range of 50 nm to 200 nm, in order to further improve the storage stability and ejection stability of the ink.

The polyethylene wax content (in terms of solid content) is preferably in the range of 0.1 to 3% by mass, and 0.3 to 3% by mass, based on the total mass of the ink (100% by mass) independently of each other. It is more preferably in the range of% by mass, and even more preferably in the range of 0.3 to 1.5% by mass. When the content is within the above range, the ink can be satisfactorily solidified and fixed even on a medium that is non-absorbent or has low absorbency, and the storage stability and ejection stability of the ink are further improved. Can be.

[3. Surfactant]
The ink may contain a surfactant. Examples of the surfactant include, but are not limited to, nonionic surfactants. The nonionic surfactant has the effect of spreading the ink uniformly on the medium. Therefore, when printing is performed using an ink containing a nonionic surfactant, a high-definition image with almost no bleeding can be obtained. Such nonionic surfactants are not limited to the following, but are, for example, silicon-based, polyoxyethylene alkyl ether-based, polyoxypropylene alkyl ether-based, polycyclic phenyl ether-based, sorbitan derivatives, and fluorine-based interfaces. Activators can be mentioned, and among them, silicon-based surfactants are preferable.

The content of the surfactant is 0.1% by mass or more and 3% by mass or less with respect to the total mass (100% by mass) of the ink because the storage stability and ejection stability of the ink are further improved. It is preferably in the range.

[4. Organic solvent]
The ink may contain a known volatile water-soluble organic solvent. However, as described above, the ink substantially does not contain glycerin (boiling point at 1 atm is 290 ° C), which is a kind of organic solvent, and alkyl polyols having a boiling point at 280 ° C or higher at 1 atm. It is preferable that (excluding the above-mentioned glycerin) is substantially not contained.

[5. Aprotic polar solvent]
The ink may contain an aprotic polar solvent. By containing the aprotic polar solvent in the ink, the above-mentioned resin particles contained in the ink are dissolved, so that clogging of the nozzle 21 can be effectively suppressed during printing. Further, since it has a property of dissolving a medium such as vinyl chloride, the adhesion of the image is improved.

The aprotic polar solvent is not particularly limited, but is one or more selected from pyrrolidones, lactones, sulfoxides, imidazolidinones, sulfolanes, urea derivatives, dialkylamides, cyclic ethers, and amide ethers. Is preferably included. Representative examples of pyrrolidones include 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone, and typical examples of lactones are γ-butyrolactone, γ-valerolactone, and ε-caprolactone. Typical examples of sulfoxides are dimethyl sulfoxide and tetramethylene sulfoxide.

Representative examples of imidazolidinones include 1,3-dimethyl-2-imidazolidinone, representative examples of sulfolanes include sulfolanes and dimethylsulfolanes, and representative examples of urea derivatives include dimethylurea. There are 1,1,3,3-tetramethylurea. Representative examples of dialkylamides include dimethylformamide and dimethylacetamide, and typical examples of cyclic ethers include 1,4-dioxane and tetrahydrofuran.

Among them, pyrrolidones, lactones, sulfoxides, and amide ethers are particularly preferable, and 2-pyrrolidone is most preferable from the viewpoint of the above-mentioned effects. The content of the aprotic polar solvent is preferably in the range of 3 to 30% by mass, more preferably in the range of 8 to 20% by mass, based on the total mass (100% by mass) of the ink. preferable.

[6. Other ingredients]
In addition to the above components, the ink may further contain a fungicide, a rust inhibitor, a chelating agent, and the like.

Next, the components of the surfactant to be mixed with the second liquid will be described.
Surfactants include cationic surfactants such as alkylamine salts and quaternary ammonium salts; anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts; alkyldimethylamine oxide. , Alkylcarboxybetaine and other amphoteric surfactants; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene / polyoxypropylene block copolymers. Etc. can be used, but among these, an anionic surfactant or a nonionic surfactant is particularly preferable.

The content of the surfactant is preferably 0.1 to 5.0% by mass with respect to the total mass of the second liquid. Further, from the viewpoint of air bubble property and defoaming property after air bubbles, the content of the surfactant is preferably 0.5 to 1.5% by mass with respect to the total mass of the second liquid. The surfactant may be only one type or two or more types. Further, the surfactant contained in the second liquid is preferably the same as the surfactant contained in the ink (first liquid), for example, the surfactant contained in the ink (first liquid). When is a nonionic surfactant, the nonionic surfactant is not limited to the following, but is, for example, silicon-based, polyoxyethylene alkyl ether-based, polyoxypropylene alkyl ether-based, polycyclic phenyl ether-based, sorbitan derivative. , And fluorine-based surfactants, and among them, silicon-based surfactants are preferable.

In particular, the foam height immediately after foaming and 5 minutes after foaming using the Rosmiles method is within the above range (the foam height immediately after foaming is 50 mm or more, and the foam height after 5 minutes of foaming is 5 mm or less). In order to achieve this, an adduct in which ethylene oxide (EO) is added to acetylene diol with an addition molar number of 4 to 30 is used as a surfactant, and the content of the adduct is set to 0 with respect to the total weight of the cleaning liquid. It is preferably 1 to 3.0% by weight. Further, the foam height immediately after foaming and 5 minutes after foaming using the Rosmiles method is within the preferable range (the foam height immediately after foaming is 100 mm or more, and the foam height 5 minutes after foaming is 5 mm or less). In order to obtain the above value, an adduct in which ethylene oxide (EO) is added to acetylene diol with an addition molar number of 10 to 20 is used, and the content of the adduct is 0.5 to 1 with respect to the total weight of the cleaning solution. It is preferably 5.5% by weight. However, if the content of the ethylene oxide adduct of acetylene diol is too large, the critical micelle concentration may be reached and an emulsion may be formed.

The surfactant has a function of making it easier for the water-based ink to wet and spread on the recording medium. The surfactants that can be used in the present invention are not particularly limited, and are anionic surfactants such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts; polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyls. Nonionic surfactants such as ethers, acetylene glycols, and polyoxyethylene / polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; silicone-based surfactants; Fluorine-based surfactants and the like can be used.

The surfactant has the effect of subdividing and dispersing the agglomerates due to the interfacial active effect between the cleaning liquid (second liquid) and the agglomerates. Further, since it has a function of lowering the surface tension of the cleaning liquid, the cleaning liquid easily penetrates between the agglomerate and the liquid injection surface 20a, and has an effect of facilitating the separation of the agglomerate from the liquid injection surface 20a.

As the surfactant, any compound having a hydrophilic portion and a hydrophobic portion in the same molecule can be preferably used. As a specific example, those represented by the following formulas (I) to (IV) are preferable. That is, the polyoxyethylene alkyl phenyl ether-based surfactant of the following formula (I), the acetylene glycol-based surfactant of the formula (II), the polyoxyethylene alkyl ether-based surfactant of the following formula (III), and the formula (IV). ) Polyoxyethylene polyoxypropylene alkyl ether-based surfactant.

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｋ：５〜２０）

(R is a hydrocarbon chain having 6 to 14 carbon atoms which may be branched, k: 5 to 20)

（ｍ、ｎ≦２０，０＜ｍ＋ｎ≦４０）

(M, n ≦ 20,0 <m + n ≦ 40)

（Ｒは分岐してもよい炭素数６〜１４の炭化水素鎖、ｎは５〜２０）

(R is a hydrocarbon chain having 6 to 14 carbon atoms which may be branched, n is 5 to 20)

（Ｒは炭素数６〜１４の炭化水素鎖、ｍ、ｎは２０以下の数）
前記式（Ｉ）〜（IV）の化合物以外では、例えばジエチレングリコールモノフェニルエーテル、エチレングリコールモノフェニルエーテル、エチレングリコールモノアリルエーテル、ジエチレングリコールモノフェニルエーテル、ジエチレングリコールモノブチルエーテル、プロピレングリコールモノブチルエーテル、テトラエチレングリコールクロロフェニルエーテル等の多価アルコールのアルキル及びアリールエーテル類、ポリオキシエチレンポリオキシプロピレンブロック共重合体等のノニオン系界面活性剤、フッ素系界面活性剤、エタノール、２−プロパノール等の低級アルコール類を用いることができるが、特にジエチレングリコールモノブチルエーテルが好ましい。

(R is a hydrocarbon chain having 6 to 14 carbon atoms, and m and n are numbers of 20 or less)
Other than the compounds of the formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl Use alkyl and aryl ethers of polyhydric alcohols such as ethers, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, and lower alcohols such as ethanol and 2-propanol. However, diethylene glycol monobutyl ether is particularly preferable.

F ... Injection direction, DS ... Small droplet, S1 ... First injection direction, S2 ... Second injection direction, ST ... Medium, 1,1A, 1B, 1C ... Liquid injection section, 7 ... Liquid injection device, 12 ... Pressure Generation chamber, 21 ... Nozzle, 100 ... Common liquid chamber, 130 ... Actuator, 216 ... Filter, 727 ... Liquid supply path, 750a, 750B ... Wiping member, 770, 771 ... Cap, 775, 775B, 775D ... Fluid injection device, 778j ... Injection port.

Claims (8)

A liquid injection unit having a nozzle capable of injecting a first liquid onto a medium,
A gas, a second liquid , and the gas with respect to the liquid injection surface of the liquid injection portion where the nozzle opens.
And a fluid injection device having a fluid injection nozzle capable of selectively injecting three types of the mixed fluid of the second liquid, and
With
The fluid injection device is
A support portion that reciprocally supports the fluid injection nozzle along the liquid injection surface of the liquid injection portion, a support portion moving mechanism that reciprocates the support portion along the liquid injection surface, and the like.
Have,
A liquid characterized by injecting any of the gas, the second liquid, and the mixed fluid onto the liquid injection surface according to the type of maintenance operation for performing maintenance of the liquid injection unit. Injection device. A liquid injection unit moving mechanism for moving the liquid injection unit is provided.
A nozzle row is formed on the liquid injection surface by arranging a plurality of nozzle openings in one direction as the nozzle row direction.
The support portion moving mechanism moves the support portion in the nozzle row direction.
The liquid injection device according to claim 1, wherein the liquid injection unit moving mechanism moves the liquid injection unit in a direction intersecting the nozzle row. The liquid injection device according to claim 1 or 2, wherein as the maintenance operation, the mixed fluid is injected onto the liquid injection surface and then the first liquid is discharged from the nozzle. A wiping member capable of wiping the liquid injection portion is provided.
The maintenance operation according to any one of claims 1 to 3, wherein the mixed fluid is sprayed onto the liquid injection surface and then the liquid injection surface is wiped by the wiping member. Liquid injection device. When the set to position the maintenance position of the fluid jet nozzle for performing maintenance operations, provided before Symbol maintenance position at a distance in the direction along the liquid ejecting surface
Equipped with a cover member
The fluid injection nozzle is located at a position facing the cover member after the maintenance operation.
The liquid injection device according to any one of claims 1 to 4 , wherein the gas is injected. A cap capable of capping the liquid injection surface of the liquid injection unit is further provided.
A fluid injection is performed on the liquid injection surface to inject either the liquid or the mixed fluid, and the liquid injection surface is provided with the cap so that the second liquid adhering to the liquid injection surface is contained in the closed space. The liquid injection device according to any one of claims 1 to 5 , wherein the liquid injection device is characterized by capping. The fluid injection nozzle is provided with an opening of a gas flow path to which the gas is supplied and an opening of a liquid flow path to which the second liquid is supplied.
The liquid flow path is connected to a storage unit that houses the second liquid.
The method according to any one of claims 1 to 6 , wherein in the fluid injection posture, the liquid level of the liquid in the reservoir is located below the opening of the gas flow path. Liquid injection device. The fluid injection nozzle includes the second liquid supplied through the opening of the liquid flow path and the second liquid.
The liquid injection device according to claim 7 , further comprising a mixing portion inside which the gas supplied through the opening of the gas flow path is mixed to generate the mixed fluid.

Images