JP7031317B2 - Discharge device and image forming device - Google Patents

Description

The present invention relates to a discharge device and an image forming device.

Patent Document 1 includes an upstream tank for storing ink supplied to the ink head and a downstream tank for storing ink discharged from the ink head, and the inside of the upstream tank and the inside of the downstream tank are each in the atmosphere. An open inkjet printer is disclosed.

Japanese Unexamined Patent Publication No. 2009-196207

Here, in a configuration in which the air chamber inside the supply unit that supplies the liquid (for example, ink) to the discharge unit (for example, the discharge head) is open to the atmosphere, the atmosphere when the air flows into the inside of the supply unit. If the humidity is low, the evaporation of the liquid inside the supply section may be promoted.

In the present invention, the liquid inside the supply section is reduced by supplying the liquid to the discharge section, and the inside of the supply section is reduced, as compared with the configuration in which the air chamber of the supply section is open to the atmosphere without being connected to the air chamber of the recovery section. The purpose is to suppress the evaporation of the liquid inside the supply unit even if air flows into the supply unit.

The first aspect is a discharge unit that discharges a liquid, a supply unit that supplies the liquid stored inside to the discharge unit, and a collection unit that collects the liquid from the discharge unit and stores the liquid inside. An air passage connecting the first air chamber formed on the liquid inside the supply unit and the second air chamber formed on the liquid inside the recovery unit, and the air passage are opened to the atmosphere. It is equipped with an open part.

The second aspect includes a liquid feeding mechanism for sending a liquid from the collecting unit to the supply unit.

In the third aspect , the liquid feeding mechanism has a storage part for storing the liquid sent from the collecting part and the liquid is sent to the supply part, and the ventilation passage has the first air chamber and the said. The second air chamber and the third air chamber formed on the liquid inside the reservoir are connected.

In the fourth aspect , the open portion is arranged at an intermediate position where the ventilation resistance to the supply portion and the ventilation resistance to the recovery portion in the ventilation passage are substantially the same.

In the fifth aspect , the ventilation resistance in the open portion is larger than the ventilation resistance in the ventilation passage.

In the sixth aspect , the open portion is a passage narrower than the ventilation passage.

In the seventh aspect, the open portion is provided with a filter for suppressing the entry of foreign matter, and the ventilation path is not provided with the filter.

Eighth aspect is a discharge unit that discharges a liquid, a supply unit that supplies the liquid stored inside to the discharge unit, and a collection unit that collects the liquid from the discharge unit and stores the liquid inside. An open path that opens the supply section to the atmosphere and an inflow path that causes the air discharged from the recovery section to flow into the inside of the supply section where the liquid has decreased due to the increase in the liquid inside the recovery section. Be prepared.

In the ninth aspect , an open path for opening the recovery unit to the atmosphere and air discharged from the supply unit due to an increase in the amount of liquid inside the supply unit are allowed to flow into the inside of the collection unit where the liquid has decreased. It has an inflow route.

In the tenth aspect , ink as a liquid is sent from the supply section to the recovery section via the discharge section due to the head difference between the transport section that transports the recording medium and the supply section and the recovery section, and the liquid feed mechanism sends the liquid. The ejection device according to any one of the first to ninth aspects, wherein the ink is returned from the collection unit to the supply unit by driving the unit, and the ink is ejected from the ejection unit to the recording medium conveyed by the transfer unit. And.

According to the configuration of the first aspect , the liquid inside the supply unit is reduced by supplying the liquid to the discharge unit, as compared with the configuration in which the air chamber of the supply unit is open to the atmosphere without being connected to the air chamber of the recovery unit. Even if air flows into the inside of the supply part, evaporation of the liquid inside the supply part can be suppressed.

According to the configuration of the second aspect , the liquid inside the recovery unit is reduced by sending the liquid to the supply unit, as compared with the configuration in which the air chamber of the recovery unit is open to the atmosphere without being connected to the air chamber of the supply unit. Even if air flows into the recovery section, evaporation of the liquid inside the recovery section can be suppressed.

According to the configuration of the third aspect , the liquid inside the storage unit is reduced by sending the liquid to the supply unit, as compared with the configuration in which the air chamber of the storage unit is open to the atmosphere without being connected to the air chamber of the supply unit. Even if air flows into the storage unit, the evaporation of the liquid inside the storage unit can be suppressed.

According to the configuration of the fourth aspect , as compared with the case where the open portions are arranged at different positions beyond the range in which the ventilation resistance to the supply portion and the ventilation resistance to the recovery portion in the ventilation passage are substantially the same. Evaporation of the liquid inside both the supply unit and the recovery unit can be suppressed.

According to the configuration of the fifth aspect , the evaporation of the liquid inside the supply portion can be suppressed as compared with the case where the ventilation resistance in the open portion is substantially the same as the ventilation resistance in the ventilation passage.

According to the configuration of the sixth aspect , it is possible to reduce the arrangement space of the open portion while suppressing the evaporation of the liquid inside the supply portion, as compared with the case where the open portion is a passage having the same thickness as the air passage.

According to the configuration of the seventh aspect , the inside of the supply section is compared with the configuration in which the filter is provided between the supply section and the open section in the ventilation path and between the recovery section and the open section in the ventilation path. A common filter can suppress the ingress of foreign matter into the supply section and the recovery section while suppressing the evaporation of the liquid.

According to the configuration of the eighth aspect , the evaporation of the liquid inside the supply unit can be suppressed as compared with the configuration in which only the atmosphere flows into the inside of the supply unit where the liquid has decreased.

According to the configuration of the ninth aspect , the evaporation of the liquid inside the recovery unit can be suppressed as compared with the configuration in which only the atmosphere flows into the inside of the recovery unit where the liquid has decreased.

According to the configuration of the tenth aspect , compared to the configuration in which the air chamber of the supply unit is open to the atmosphere without being connected to the air chamber of the recovery unit, or the configuration in which only the air flows into the inside of the supply unit where the liquid is reduced. In comparison with the above, it is possible to provide an image forming apparatus that suppresses the increase in the viscosity of the ink due to the evaporation of the water content of the ink in the supply unit.

It is a schematic diagram which shows the structure of the inkjet recording apparatus which concerns on this embodiment. It is a schematic diagram which shows the structure of the discharge head and the supply mechanism which concerns on this embodiment. It is a schematic diagram which shows the structure of the discharge head and the supply mechanism which concerns on a comparative example. It is a schematic diagram which shows the structure of the discharge head and the supply mechanism which concerns on the 1st modification. It is a schematic diagram which shows the other example of the supply mechanism which concerns on the 1st modification. It is a schematic diagram which shows the other example of the supply mechanism which concerns on the 1st modification. It is a schematic diagram which shows the other example of the supply mechanism which concerns on the 1st modification. It is a schematic diagram which shows the structure of the discharge head and the supply mechanism which concerns on the 2nd modification. It is a schematic diagram which shows the structure of the discharge head and the supply mechanism which concerns on 3rd modification. It is a schematic diagram which shows the other example of the supply mechanism which concerns on 3rd modification. It is a schematic diagram which shows the structure of the evaluation apparatus which imitated the structure of the comparative example shown in FIG. It is a schematic diagram which shows the structure of the evaluation apparatus which imitated the structure of this embodiment shown in FIG. It is a graph which shows the evaluation result.

Hereinafter, an example of the embodiment according to the present invention will be described with reference to the drawings.

(Inkjet recording device 10)
The inkjet recording apparatus 10 according to the present embodiment will be described. FIG. 1 is a schematic view showing the configuration of the inkjet recording apparatus 10.

The inkjet recording device 10 is an example of an image forming device that forms an image on a recording medium. Specifically, the inkjet recording device 10 is a device that ejects ink onto a recording medium to form an image. More specifically, as shown in FIG. 1, the inkjet recording device 10 is a device that ejects ink droplets onto continuous paper P (an example of a recording medium) to form an image on continuous paper P. The continuous paper P is a long recording medium having a length in the transport direction.

As shown in FIG. 1, the inkjet recording device 10 includes a transport mechanism 20 and a discharge mechanism 12. Hereinafter, a specific configuration of each part (transport mechanism 20 and ejection mechanism 12) of the inkjet recording device 10 will be described.

(Transport mechanism 20)
The transport mechanism 20 is an example of a transport unit that transports a recording medium. Specifically, the transport mechanism 20 is a mechanism for transporting continuous paper P. More specifically, as shown in FIG. 1, the transport mechanism 20 has a winding roll 22, a winding roll 24, and a plurality of winding rolls 26.

The unwinding roll 22 is a roll for unwinding the continuous paper P. The continuous paper P is wound around the unwinding roll 22 in advance. The unwinding roll 22 unwinds the wound continuous paper P by rotating.

The plurality of winding rolls 26 are rolls on which continuous paper P is wound. Specifically, the plurality of winding rolls 26 are wound around the continuous paper P between the unwinding roll 22 and the winding roll 24. As a result, the transport path of the continuous paper P from the unwinding roll 22 to the winding roll 24 is defined.

The take-up roll 24 is a roll for taking up the continuous paper P. The take-up roll 24 is rotationally driven by the drive unit 28. As a result, the take-up roll 24 winds up the continuous paper P, and the unwind roll 22 winds up the continuous paper P. Then, the continuous paper P is wound by the winding roll 24 and is unwound by the unwinding roll 22 to be conveyed. The winding roll 26 rotates in accordance with the continuous paper P to be conveyed. In each figure, the transport direction of the continuous paper P (hereinafter, may be simply referred to as “transport direction”) is indicated by an arrow A as appropriate.

(Discharge mechanism 12)
The ejection mechanism 12 is an example of an ejection device that ejects ink as a liquid from the ejection unit to the recording medium conveyed by the transport unit. Specifically, the ejection mechanism 12 is a mechanism for ejecting ink droplets from the ejection heads 32Y to 32, which will be described later, onto the continuous paper P conveyed by the conveying mechanism 20. More specifically, the discharge mechanism 12 includes a discharge unit 30 and a supply mechanism 40. Hereinafter, a specific configuration of each part (discharge unit 30 and supply mechanism 40) of the discharge mechanism 12 will be described.

(Discharge unit 30)
The ejection unit 30 is a unit that ejects ink droplets (an example of droplets). Specifically, as shown in FIG. 1, the discharge unit 30 has discharge heads 32Y, 32M, 32C, 32K (hereinafter referred to as 32Y to 32K).

Each discharge head 32Y to 32K is an example of a discharge unit that discharges a liquid. Specifically, each ejection head 32Y to 32K is a head that ejects ink droplets (an example of droplets) from the nozzle 30N onto the continuous paper P. More specifically, the ejection heads 32Y to 32K are heads that eject ink droplets of each color of yellow (Y), magenta (M), cyan (C), and black (K) onto the continuous paper P.

As shown in FIG. 1, the discharge heads 32Y to 32K are arranged in this order toward the upstream side in the transport direction of the continuous paper P. Each of the ejection heads 32Y to 32K has a length in the width direction of the continuous paper P (the crossing direction intersecting the transport direction of the continuous paper P).

Each of the discharge heads 32Y to 32K has a nozzle surface 30S on which the nozzle 30N is formed. The nozzle surfaces 30S of the discharge heads 32Y to 32K face downward and face the continuous paper P conveyed by the transfer mechanism 20. Each of the ejection heads 32Y to 32K ejects ink droplets from the nozzle 30N onto the continuous paper P by a known method such as a thermal method or a piezoelectric method to form an image on the continuous paper P.

The ink used in each of the ejection heads 32Y to 32K is, for example, a water-based ink. The water-based ink contains, for example, a solvent containing water as a main component, a colorant (pigment or dye), and other additives.

(Supply mechanism 40)
The supply mechanism 40 is a mechanism for supplying ink to the ejection heads 32Y to 32K, and is provided for each ejection head 32Y to 32K. Specifically, the supply mechanism 40 is a mechanism that supplies ink to the ejection heads 32Y to 32K and collects the ink supplied to the ejection heads 32Y to 32K. More specifically, the supply mechanism 40 is also a mechanism for circulating ink by supplying ink to the ejection heads 32Y to 32K and collecting the ink supplied to the ejection heads 32Y to 32K.

In the following, the supply mechanism 40 that supplies ink to the ejection head 32Y will be described, but the ejection heads 32M, 32C, and 32K are similarly configured. Further, FIG. 1 illustrates only the supply mechanism 40 that supplies ink to the ejection head 32Y. FIG. 2 is a schematic diagram schematically showing the configurations of the discharge head 32Y and the supply mechanism 40.

As shown in FIG. 2, the supply mechanism 40 includes a supply unit 42, a recovery unit 43, a ventilation passage 60, an open passage 62, and a liquid feeding mechanism 50.

The supply unit 42 is an example of a supply unit that supplies the liquid stored inside to the discharge unit. Specifically, the supply unit 42 has a function of storing ink inside and supplying the ink to the ejection head 32Y. More specifically, the supply unit 42 has a supply tank 44 and a supply path 46.

The supply tank 44 functions as a storage unit for storing the ink supplied to the discharge head 32Y. Specifically, the supply tank 44 is composed of a container for storing ink supplied to the ejection head 32Y. More specifically, the supply tank 44 has a supply port 44A, a collection port 44B, and an opening port 44C, and is composed of a container closed except for the supply port 44A, the collection port 44B, and the opening port 44C. ing.

The supply tank 44 is provided with a detection unit 48 for detecting the height of the liquid level of the ink stored inside the supply tank 44. Specifically, the detection unit 48 detects a predetermined upper limit and lower limit at the height of the liquid level. As the detection unit 48, for example, a float sensor is used.

The supply path 46 is a passage for supplying the ink of the supply tank 44 to the ejection head 32Y. Specifically, in the supply path 46, one end (upstream end) is connected to the supply tank 44, and the other end (downstream end) is connected to the discharge head 32Y. The supply path 46 is formed inside a supply pipe 462 made of a tube or the like. Specifically, one end (upstream end) of the supply pipe 462 is inserted into the inside of the supply tank 44 through the supply port 44A of the supply tank 44, and is arranged in a state of being immersed in the ink inside the supply tank 44. There is. The supply port 44A and the supply pipe 462 are sealed.

The collection unit 43 is an example of a collection unit that collects a liquid from a discharge unit and stores the liquid inside. Specifically, the recovery unit 43 has a function of collecting ink from the ejection head 32Y and storing the ink inside. More specifically, the recovery unit 43 has a recovery tank 45 and a recovery path 47.

The recovery tank 45 functions as a storage unit for storing the ink recovered from the ejection head 32Y. Specifically, the recovery tank 45 is composed of a container for storing ink. More specifically, the recovery tank 45 has a supply port 45A, a recovery port 45B, and an opening port 45C, and is composed of a container closed except for the supply port 45A, the recovery port 45B, and the opening port 45C. ing.

The recovery path 47 is a passage for collecting ink from the discharge head 32Y to the recovery tank 45. Specifically, one end of the recovery path 47 is connected to the discharge head 32Y, and the other end is connected to the recovery tank 45. The recovery path 47 is formed inside a recovery tube 471 made of a tube or the like. Specifically, the other end (downstream end) of the recovery pipe 471 is inserted into the inside of the recovery tank 45 through the recovery port 45B of the recovery tank 45. The collection port 45B and the collection tube 471 are sealed.

The liquid feeding mechanism 50 is an example of a liquid feeding mechanism that sends a liquid from the collecting unit to the supply unit. Specifically, the liquid feeding mechanism 50 is a mechanism for feeding ink from the recovery tank 45 to the supply tank 44. More specifically, the liquid feeding mechanism 50 includes a liquid feeding passage 52 and a pump 54.

The liquid feeding path 52 is a passage for sending ink from the collection tank 45 to the supply tank 44. Specifically, one end of the liquid feeding path 52 is connected to the recovery tank 45, and the other end is connected to the supply tank 44. The liquid feeding path 52 is formed inside a liquid feeding pipe 521 made of a tube or the like. Specifically, one end (upstream end) of the liquid feed pipe 521 is inserted into the inside of the recovery tank 45 through the supply port 45A of the recovery tank 45, and is arranged in a state of being immersed in the ink inside the recovery tank 45. ing. The supply port 45A and the liquid feed pipe 521 are sealed.

Further, the other end (downstream end) of the liquid feeding pipe 521 is specifically inserted into the inside of the supply tank 44 through the collection port 44B of the supply tank 44. The collection port 44B and the liquid feed pipe 521 are sealed. Further, the liquid feeding path 52 may be provided with a degassing mechanism for removing the dissolved gas in the ink.

The pump 54 is an example of a liquid feeding unit that sends ink. Specifically, the pump 54 is driven to send the ink in the recovery tank 45 from the recovery tank 45 to the supply tank 44 through the liquid feed path 52.

When the ejection head 32Y ejects ink and the ink is consumed, the ink is replenished to the supply tank 44 through the liquid feeding path 52 (see arrow D). Specifically, for example, the ink stored in the ink tank (not shown) is replenished to the supply tank 44 through the liquid feeding path 52 by a pump (not shown).

As described above, in the supply mechanism 40, the supply tank 44, the supply path 46, the discharge head 32Y, the recovery path 47, the recovery tank 45, and the liquid feeding path 52 form a circulation path for circulating ink in this order. ..

The liquid level of the supply tank 44 is arranged at a position higher than the liquid level of the recovery tank 45, and has a head difference with respect to the liquid level of the recovery tank 45. As a result, an ink flow for sending ink from the supply tank 44 to the recovery tank 45 via the discharge head 32Y is generated, and a back pressure (negative pressure) is generated for the ink in the discharge head 32Y.

Further, the ink in the recovery tank 45 is sent to the supply tank 44 by the pump 54 so that the height of the liquid level in the supply tank 44 is maintained within a predetermined upper limit and lower limit. Specifically, when the above-mentioned detection unit 48 detects that the liquid level height of the ink in the supply tank 44 has reached a predetermined lower limit, the pump 54 is driven and the ink in the recovery tank 45 is supplied to the supply tank. Sent to 44. When the above-mentioned detection unit 48 detects that the liquid level height has reached a predetermined upper limit, the driving of the pump 54 is stopped.

As described above, ink is sent from the supply tank 44 to the recovery tank 45 via the discharge head 32Y due to the head difference of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45, and the ink is recovered by driving the pump 54. Return from the tank 45 to the supply tank 44. That is, in the supply mechanism 40, the ink is circulated in the above-mentioned circulation path by the head difference of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45 and the drive of the pump 54. In the present embodiment, in the operation of the inkjet recording device 10, the ink is circulated by the above-mentioned circulation path regardless of whether the ink of the ejection head 32Y is ejected or not.

When stopping the circulation of ink, for example, by lowering the supply tank 44, the heights of the liquid level of the recovery tank 45 and the liquid level of the supply tank 44 are made uniform. In this way, by adjusting (controlling) the relative height of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45, the circulation of the ink and the stop of the circulation can be switched. Further, it is also possible to adjust the circulation amount (circulation speed) of the ink by adjusting (controlling) the relative height.

The air passage 60 is an example of a air passage connecting the first air chamber formed on the liquid inside the supply unit and the second air chamber formed on the liquid inside the recovery unit. Specifically, the air passage 60 connects the first air chamber 441 formed on the ink inside the supply tank 44 and the second air chamber 452 formed on the ink inside the recovery tank 45. I'm out. More specifically, the ventilation passage 60 is formed inside a ventilation pipe 602 made of a tube or the like. One end of the ventilation pipe 602 is connected to the upper opening 44C of the supply tank 44, and the other end is connected to the upper opening 45C of the recovery tank 45. The space between the opening 44C and the ventilation pipe 602 and the space between the opening 45C and the ventilation pipe 602 are sealed. Further, the ventilation pipe 602 has a constant inner diameter from the supply tank 44 to the recovery tank 45. Therefore, the passage width (thickness) of the ventilation passage 60 is constant from the supply tank 44 to the recovery tank 45.

The air passage 60 connected to the supply tank 44 and the recovery tank 45 in this way is bidirectional (see arrow B) between the first air chamber 441 of the supply tank 44 and the second air chamber 452 of the recovery tank 45. ) Has a function to enable the flow of air.

Further, the ventilation passage 60 is also an example of an inflow path in which the air discharged from the recovery section due to the increase in the liquid inside the recovery section is allowed to flow into the inside of the supply section where the liquid has decreased. Specifically, the ventilation path 60 causes the air discharged from the recovery tank 45 due to the increase in ink inside the recovery tank 45 in the process of ink circulation to flow into the inside of the supply tank 44 whose space is expanded due to the decrease in ink. It has a function to make it.

Further, the ventilation passage 60 is also an example of an inflow path in which the air discharged from the supply section due to the increase in the liquid inside the supply section is allowed to flow into the inside of the recovery section where the liquid has decreased. Specifically, the ventilation path 60 causes the air discharged from the supply tank 44 due to the increase in ink inside the supply tank 44 in the process of ink circulation to flow into the inside of the recovery tank 45 whose space is expanded due to the decrease in ink. It has a function to make it.

The open path 62 is an example of an open portion that opens the ventilation path to the atmosphere. Specifically, the open passage 62 is a passage connected to the intermediate portion 60A of the ventilation passage 60 and opens the ventilation passage 60 to the atmosphere at the intermediate portion 60A. More specifically, the open passage 62 has a function of allowing air to flow in both directions (see arrow C) between the atmosphere (outside) and the ventilation passage 60.

Further, the open path 62 is formed inside an open pipe 622 made of a tube or the like. The open pipe 622 has a constant inner diameter from one end to the other. Therefore, the passage width (thickness) of the open path 62 is constant from one end to the other end. Further, the inner diameter of the open pipe 622 is, for example, the same as the inner diameter of the ventilation pipe 602. That is, the passage width (thickness) of the open passage 62 is, for example, the same as the passage width (thickness) of the ventilation passage 60.

Further, in the present embodiment, the open passage 62 is connected to a position closer to the supply tank 44 in the ventilation passage 60. Therefore, the ventilation resistance from the intermediate portion 60A to the recovery tank 45 is made larger than the ventilation resistance from the intermediate portion 60A to the supply tank 44. That is, the open passage 62 is arranged at a position where the ventilation resistance up to the recovery tank 45 in the ventilation passage 60 is larger than the ventilation resistance up to the supply tank 44. As will be described later, the open passage 62 may have a configuration in which the ventilation resistance up to the supply tank 44 and the ventilation resistance up to the recovery tank 45 in the ventilation passage 60 are arranged at substantially the same position.

Further, in the present embodiment, the ventilation resistance in the open passage 62 is smaller than the ventilation resistance in the ventilation passage 60. Specifically, the ventilation resistance in the entire length of the open passage 62 is smaller than the ventilation resistance in the entire length of the ventilation passage 60. More specifically, the ventilation resistance in the entire length of the open path 62 is smaller than the ventilation resistance from the intermediate portion 60A to the supply tank 44 and the ventilation resistance from the intermediate portion 60A to the recovery tank 45, respectively. .. The ventilation resistance in the open passage 62 may be the same as the ventilation resistance in the ventilation passage 60. Further, the ventilation resistance in the open passage 62 may be larger than the ventilation resistance in the ventilation passage 60, as will be described later.

Further, the ventilation path 60 and the open path 62 are also examples of open paths that open the supply unit to the atmosphere. Specifically, the passage from the supply tank 44 to the intermediate portion 60A in the ventilation path 60 and the open path 62 form an open path for opening the inside of the supply tank 44 to the atmosphere.

Further, the ventilation path 60 and the open path 62 are also examples of open paths that open the recovery unit to the atmosphere. Specifically, the passage from the recovery tank 45 to the intermediate portion 60A in the ventilation path 60 and the open path 62 constitute an open path for opening the inside of the recovery tank 45 to the atmosphere.

(Action of this embodiment)
According to the supply mechanism 40 of the inkjet recording apparatus 10, the above-mentioned circulation paths (supply tank 44, supply path 46, ejection head 32Y, recovery path 47, recovery tank 45) regardless of whether ink is ejected or not ejected from the ejection head 32Y. And the route by the liquid feeding path 52), the ink is circulated.

Here, in the supply mechanism 40 of the inkjet recording device 10, the ink of the supply tank 44 is sent to the recovery tank 45 via the discharge head 32Y due to the head difference of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45. As a result, the ink in the supply tank 44 decreases and the ink in the recovery tank 45 increases.

In the recovery tank 45, air is discharged from the recovery tank 45 to the ventilation passage 60 due to the increase in ink inside. On the other hand, in the supply tank 44, the internal space is expanded due to the decrease of the ink inside. Then, the air discharged from the recovery tank 45 flows into the inside of the supply tank 44 whose space is expanded through the ventilation passage 60.

In other words, the inside of the recovery tank 45 has a positive pressure (higher pressure than the atmosphere) due to the increase in ink, and the inside of the supply tank 44 has a negative pressure (lower pressure than the atmosphere) due to the decrease in ink. Therefore, the air inside the recovery tank 45 is sent to the supply tank 44 through the ventilation passage 60 without going to the open passage 62.

Here, as shown in FIG. 3, in the configuration in which the air chamber of the supply tank 44 is open to the atmosphere without being connected to the air chamber of the recovery tank 45 (first comparative example), the space is expanded due to the reduction of ink. Air flows into the inside of the supply tank 44. When the humidity of the atmosphere flowing into the inside of the supply tank 44 is low, the evaporation of the water content of the ink inside the supply tank 44 is promoted.

On the other hand, in the present embodiment, as described above, the air discharged from the inside of the recovery tank 45 flows into the inside of the supply tank 44 whose space is expanded due to the decrease of ink through the ventilation passage 60. Since the inside of the recovery tank 45 is a closed space in which ink is stored, the air discharged from the inside of the recovery tank 45 is maintained at a higher humidity than the atmosphere.

Therefore, even if air flows into the inside of the supply tank 44, the evaporation of the water content of the ink inside the supply tank 44 is suppressed as compared with the first comparative example.

When the ink circulates in the non-discharged state of the discharge head 32Y, the ink flows into the recovery tank 45 by the amount of the ink discharged from the supply tank 44, so that the air discharged from the recovery tank 45 is discharged. The space inside the supply tank 44 is expanded by the amount (volume). Therefore, it is difficult for the atmosphere to flow into the supply tank 44.

On the other hand, when the ink circulates while the ejection head 32Y is ejected, the amount of ink flowing into the recovery tank 45 is smaller than the amount of ink ejected from the supply tank 44 because the ink is consumed. Therefore, the amount (volume) in which the space inside the supply tank 44 is expanded is larger than the amount (volume) of the air discharged from the recovery tank 45. Therefore, the atmosphere flows into the supply tank 44.

Further, in the supply mechanism 40 of the inkjet recording device 10, when the detection unit 48 detects that the liquid level height of the ink in the supply tank 44 has reached a predetermined lower limit, the pump 54 is driven to drive the recovery tank 45. Ink is sent to the supply tank 44. As a result, the ink in the recovery tank 45 decreases and the ink in the supply tank 44 increases.

In the supply tank 44, air is discharged from the supply tank 44 to the air passage 60 due to the increase in ink inside. On the other hand, in the recovery tank 45, the internal space is expanded due to the decrease of the ink inside. Then, the air discharged from the supply tank 44 flows into the inside of the recovery tank 45 whose space is expanded through the ventilation passage 60.

In other words, the inside of the supply tank 44 has a positive pressure (higher pressure than the atmosphere) due to the increase in ink, and the inside of the recovery tank 45 has a negative pressure (lower pressure than the atmosphere) due to the decrease in ink. Therefore, the air inside the supply tank 44 is sent to the recovery tank 45 through the ventilation passage 60 without going to the open passage 62.

Here, as shown in FIG. 3, in the configuration in which the air chamber of the recovery tank 45 is open to the atmosphere without being connected to the air chamber of the supply tank 44 (second comparative example), the space is expanded due to the reduction of ink. Air flows into the inside of the recovery tank 45. When the humidity of the atmosphere flowing into the recovery tank 45 is low, the evaporation of the ink moisture inside the recovery tank 45 is promoted.

On the other hand, in the present embodiment, as described above, the air discharged from the inside of the supply tank 44 flows into the inside of the recovery tank 45 whose space is expanded due to the decrease of ink through the ventilation passage 60. Since the inside of the supply tank 44 is a closed space in which ink is stored, the air discharged from the inside of the supply tank 44 is maintained at a higher humidity than the atmosphere.

Therefore, even if air flows into the recovery tank 45, evaporation of the ink water inside the recovery tank 45 is suppressed as compared with the second comparative example.

As described above, in the present embodiment, the evaporation of the ink moisture inside the supply tank 44 and the recovery tank 45 is suppressed, so that the image defect due to the evaporation of the ink moisture and the increase in the viscosity of the ink is suppressed. To.

(First modification)
In the above-described embodiment, the liquid feeding mechanism 50 has a liquid feeding passage 52 and a pump 54, but the liquid feeding mechanism 50 is not limited to this. As an example of the liquid feeding mechanism that sends the liquid from the collecting unit to the supply unit, the liquid feeding mechanism 150 shown in FIG. 4 may be used.

The liquid feeding mechanism 150 includes a storage tank 155, a liquid feeding passage 152, a pump 154, a liquid feeding passage 156, and a pump 158.

The storage tank 155 is an example of a storage unit that stores the liquid sent from the collection unit and the liquid is sent to the supply unit. Specifically, the storage tank 155 is a tank that stores the ink sent from the recovery tank 45 and sends the ink to the supply tank 44. More specifically, the storage tank 155 has a supply port 155A, a recovery port 155B, and an opening port 155C, and is composed of a container closed except for the supply port 155A, the recovery port 155B, and the opening port 155C. ing.

The liquid feeding path 152 is a passage for sending ink from the recovery tank 45 to the storage tank 155. Specifically, one end of the liquid feeding path 152 is connected to the recovery tank 45, and the other end is connected to the storage tank 155. The liquid feeding path 152 is formed inside a liquid feeding pipe 162 made of a tube or the like. Specifically, one end (upstream end) of the liquid feed pipe 162 is inserted into the inside of the recovery tank 45 through the supply port 45A of the recovery tank 45, and is arranged in a state of being immersed in the ink inside the recovery tank 45. ing. The supply port 45A and the liquid feed pipe 162 are sealed.

Further, the other end (downstream end) of the liquid feeding pipe 162 is specifically inserted into the storage tank 155 through the collection port 155B of the storage tank 155. The collection port 155B and the liquid feed pipe 162 are sealed.

The pump 154 is an example of a liquid feeding unit that sends ink. Specifically, the pump 154 is driven to send the ink in the recovery tank 45 from the recovery tank 45 to the storage tank 155 through the liquid feed path 152.

The liquid feeding path 156 is a passage for sending ink from the storage tank 155 to the supply tank 44. Specifically, one end of the liquid feeding path 156 is connected to the storage tank 155, and the other end is connected to the supply tank 44. The liquid feeding passage 156 is formed inside a liquid feeding pipe 166 made of a tube or the like. Specifically, one end (upstream end) of the liquid feed pipe 166 is inserted into the inside of the storage tank 155 through the supply port 155A of the storage tank 155, and is arranged in a state of being immersed in the ink inside the storage tank 155. ing. The supply port 155A and the liquid feed pipe 166 are sealed.

Further, the other end (downstream end) of the liquid feeding pipe 166 is specifically inserted into the inside of the supply tank 44 through the collection port 44B of the supply tank 44. The collection port 44B and the liquid feed pipe 166 are sealed.

The pump 158 is an example of a liquid feeding unit that sends ink. Specifically, the pump 158 is driven to send the ink in the storage tank 155 from the storage tank 155 to the supply tank 44 through the liquid feed path 156.

In the first modification, the ink is circulated in this order by the supply tank 44, the supply path 46, the discharge head 32Y, the recovery path 47, the recovery tank 45, the liquid feed path 152, the storage tank 155, and the liquid feed path 156. Is formed.

Further, in the first modification, a detection unit 149 for detecting the height of the liquid level of the ink stored inside the recovery tank 45 is provided. Specifically, the detection unit 149 detects a predetermined upper limit in the height of the liquid level. As the detection unit 149, for example, a float sensor is used.

Then, when the detection unit 149 detects that the height of the ink liquid level in the recovery tank 45 has reached a predetermined upper limit, the pump 154 is driven and the ink in the recovery tank 45 is sent to the storage tank 155. Will be.

Further, the ink of the storage tank 155 is sent to the supply tank 44 by the pump 158 so that the height of the liquid level of the supply tank 44 is maintained within a predetermined upper limit and lower limit. Specifically, when the above-mentioned detection unit 48 detects a predetermined lower limit of the liquid level height of the ink in the supply tank 44, the pump 158 is driven and the ink in the storage tank 155 is sent to the supply tank 44. Will be. When the above-mentioned detection unit 48 detects a predetermined lower limit of the liquid level, the driving of the pump 158 is stopped.

Further, a replenishment tank for storing the ink to be replenished in the storage tank 155 and a mechanism for sending the ink from the replenishment tank may be provided. Further, the storage tank 155 may be a replaceable tank (specifically, an ink cartridge).

As described above, in the first modification, the ink is circulated in the above-mentioned circulation path by the head difference of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45, the pump 154, and the pump 158. In the present embodiment, in the operation of the inkjet recording device 10, the ink is circulated by the above-mentioned circulation path regardless of whether the ink of the ejection head 32Y is ejected or not.

Further, in the first modification, the ventilation passage 60 is branched and connected to the opening port 155C at the upper part of the storage tank 155. Therefore, the air passage 60 connects the first air chamber 441 of the supply tank 44, the second air chamber 452 of the recovery tank 45, and the third air chamber 153 formed on the ink inside the storage tank 155. I'm out.

Therefore, in the first modification, the air passage 60 further enables bidirectional air flow between the first air chamber 441 of the supply tank 44 and the third air chamber 153 of the storage tank 155. Air can flow in both directions between the second air chamber 452 of the recovery tank 45 and the third air chamber 153 of the storage tank 155.

Then, in the first modification, as described above, when the detection unit 149 detects that the height of the ink liquid level in the recovery tank 45 has reached a predetermined upper limit, the pump 154 is driven. The ink in the recovery tank 45 is sent to the storage tank 155. As a result, the ink in the recovery tank 45 is reduced and the ink in the storage tank 155 is increased.

In the storage tank 155, air is discharged from the storage tank 155 to the air passage 60 due to the increase in ink inside. On the other hand, in the recovery tank 45, the internal space is expanded due to the decrease of the ink inside. Then, the air discharged from the storage tank 155 flows into the inside of the recovery tank 45 whose space is expanded through the ventilation passage 60.

In other words, the inside of the storage tank 155 is set to positive pressure (higher pressure than the atmosphere) due to the increase in ink, and the inside of the recovery tank 45 is set to negative pressure (lower pressure than the atmosphere) due to the decrease in ink. Therefore, the air inside the storage tank 155 is sent to the recovery tank 45 through the ventilation passage 60 without going to the open passage 62.

Here, in the configuration in which the air chamber of the recovery tank 45 is open to the atmosphere without being connected to the air chamber of the storage tank 155 (third comparative example), the space inside the recovery tank 45 is expanded due to the decrease in ink. , The atmosphere flows in. When the humidity of the atmosphere flowing into the recovery tank 45 is low, the evaporation of the ink moisture inside the recovery tank 45 is promoted.

On the other hand, in the present embodiment, as described above, the air discharged from the inside of the storage tank 155 flows into the inside of the recovery tank 45 whose space is expanded due to the decrease of ink through the ventilation passage 60. Since the inside of the storage tank 155 is a closed space in which ink is stored, the air discharged from the inside of the storage tank 155 is maintained at a higher humidity than the atmosphere.

Therefore, even if air flows into the recovery tank 45, evaporation of the ink water inside the recovery tank 45 is suppressed as compared with the third comparative example.

Further, in the first modification, as described above, when the detection unit 48 detects a predetermined lower limit of the liquid level height of the ink in the supply tank 44, the pump 158 is driven to drive the ink in the storage tank 155. Is sent to the supply tank 44. As a result, the ink in the storage tank 155 is reduced and the ink in the supply tank 44 is increased.

In the supply tank 44, air is discharged from the supply tank 44 to the air passage 60 due to the increase in ink inside. On the other hand, in the storage tank 155, the internal space is expanded due to the decrease of the ink inside. Then, the air discharged from the supply tank 44 flows into the inside of the storage tank 155 whose space is expanded through the ventilation passage 60.

In other words, the inside of the supply tank 44 has a positive pressure (higher pressure than the atmosphere) due to the increase in ink, and the inside of the storage tank 155 has a negative pressure (lower pressure than the atmosphere) due to the decrease in ink. Therefore, the air inside the supply tank 44 is sent to the storage tank 155 through the ventilation passage 60 without going to the open passage 62.

Here, in the configuration in which the air chamber of the storage tank 155 is open to the atmosphere without being connected to the air chamber of the supply tank 44 (fourth comparative example), the space inside the storage tank 155 is expanded due to the decrease in ink. , The atmosphere flows in. When the humidity of the atmosphere flowing into the storage tank 155 is low, the evaporation of the ink moisture inside the storage tank 155 is promoted.

On the other hand, in the present embodiment, as described above, the air discharged from the inside of the supply tank 44 flows into the inside of the storage tank 155 whose space is expanded due to the decrease of ink through the ventilation passage 60. Since the inside of the supply tank 44 is a closed space in which ink is stored, the air discharged from the inside of the supply tank 44 is maintained at a higher humidity than the atmosphere.

Therefore, even if air flows into the storage tank 155, evaporation of ink water inside the storage tank 155 is suppressed as compared with the fourth comparative example.

(Other grasps in the first modification)
In the above-mentioned first modification, the liquid feed passage 152, the pump 154, the storage tank 155, the liquid feed passage 156 and the pump 158 have been described as the constituent parts of the liquid feed mechanism 150, but the present invention is not limited thereto. For example, the liquid feeding path 152, the pump 154, and the storage tank 155 may be grasped as the constituent parts of the collection unit 43, and the liquid feeding passage 156 and the pump 158 may be grasped as the constituent parts of the liquid feeding mechanism 150. In the case of this grasp, the collection unit 43 has a collection tank 45, a collection path 47, a liquid supply path 152, a pump 154, and a storage tank 155.

Further, in the case of this grasp, the third air chamber 153 of the storage tank 155 is grasped as an example of the second air chamber of the recovery unit. As shown in FIG. 5, the air passage 60 as an example of the air passage connecting the first air chamber of the supply unit and the second air chamber of the recovery unit is stored with the first air chamber 441 of the supply tank 44. It may be configured to connect only to the third air chamber 153 of the tank 155. In this case, the second air chamber 452 of the recovery tank 45 is independently opened to the atmosphere. Also in this configuration, when ink is sent from the storage tank 155 to the supply tank 44, the air in the supply tank 44 is sent to the storage tank 155. Therefore, the evaporation of ink water inside the storage tank 155 is suppressed.

As shown in FIG. 6, the ventilation passage 60 connects only the first air chamber 441 of the supply tank 44 and the second air chamber 452 of the recovery tank 45, and the third air chamber 153 of the storage tank 155 is independent. It may be configured to be open to the atmosphere.

Further, the storage tank 155, the liquid feeding passage 156 and the pump 158 may be grasped as the constituent parts of the supply unit 42, and the liquid feeding passage 152 and the pump 154 may be grasped as the constituent parts of the liquid feeding mechanism 150. In the case of this grasp, the supply unit 42 has a supply tank 44, a supply path 46, a storage tank 155, a liquid feed path 156, and a pump 158.

Further, in the case of this grasp, the third air chamber 153 of the storage tank 155 is grasped as an example of the first air chamber of the supply unit. As shown in FIG. 7, the ventilation path 60 as an example of the ventilation path connecting the first air chamber of the supply section and the second air chamber of the recovery section is stored with the second air chamber 452 of the recovery tank 45. It may be configured to connect only to the third air chamber 153 of the tank 155. In this case, the first air chamber 441 of the supply tank 44 is independently opened to the atmosphere. Also in this configuration, when ink is sent from the recovery tank 45 to the storage tank 155, the air in the storage tank 155 is sent to the recovery tank 45. Therefore, evaporation of ink water inside the recovery tank 45 is suppressed.

(Second modification)
In the above-described embodiment, the open passage 62 is arranged at a position where the ventilation resistance up to the recovery tank 45 in the ventilation passage 60 is larger than the ventilation resistance up to the supply tank 44, but the present invention is not limited to this. As shown in FIG. 8, the open passage 62 is configured such that the ventilation resistance up to the supply tank 44 and the ventilation resistance up to the recovery tank 45 in the ventilation passage 60 are arranged at substantially the same intermediate position 62B. good.

In the configuration shown in FIG. 8, the cross-sectional area of the ventilation path 60 is constant from the supply tank 44 to the recovery tank 45, and the open path is located at a position where the distances from the supply tank 44 and the recovery tank 45 are the same. 62 is arranged.

In addition, "the ventilation resistance to the supply tank 44 in the ventilation passage 60 and the ventilation resistance to the recovery tank 45 are substantially the same" means that the ventilation resistance to the supply tank 44 and the ventilation to the recovery tank 45 in the ventilation passage 60 are substantially the same. The case where the ratio with the resistance is, for example, 0.9 or more and 1.1 or less is applicable.

According to the configuration of the second modification, the ventilation resistance up to the supply tank 44 and the ventilation resistance up to the recovery tank 45 in the ventilation passage 60 are different beyond substantially the same range, as compared with the case where the supply tank 44 and the recovery tank 44 and the recovery tank 45 are different. Evaporation of ink moisture inside both tanks 45 is suppressed.

(Third modification example)
In the above-described embodiment, the ventilation resistance in the open passage 62 is smaller than the ventilation resistance in the ventilation passage 60, but the present invention is not limited to this. For example, the ventilation resistance in the open passage 62 may be made larger than the ventilation resistance in the ventilation passage 60. In the third modification, specifically, the ventilation resistance in the entire length of the open path 62 is at least the ventilation resistance from the intermediate portion 60A to the supply tank 44 and the ventilation resistance from the intermediate portion 60A to the recovery tank 45, respectively. Is made larger than. Further, the ventilation resistance in the entire length of the open passage 62 may be larger than the ventilation resistance in the entire length of the ventilation passage 60.

Specifically, as shown in FIG. 9, the open passage 62 is composed of, for example, a passage extending from the ventilation passage 60 and narrower than the ventilation passage 60. Further, the length of the open path 62 may be longer than, for example, the length from the intermediate portion 60A to the supply tank 44 and the length from the intermediate portion 60A to the recovery tank 45, respectively. Further, the length of the open passage 62 may be longer than the length of the entire ventilation passage 60. Further, the open path 62 may have a spiral shape or a labyrinth shape (maze shape).

According to the configuration shown in FIG. 9, since the air flow resistance in the open path 62 is less likely to flow through the open path 62 than in the case where the ventilation resistance in the open path 60 is the same, the supply tank 44 and the recovery tank 45 Evaporation of ink moisture inside is suppressed.

According to the configuration shown in FIG. 9, as compared with the case where the open passage 62 is a passage having the same thickness as the ventilation passage 60, the arrangement space of the open passage 62 is suppressed while suppressing the evaporation of the ink moisture inside the supply tank 44. Is reduced.

The configuration shown in FIG. 10 may be used as a configuration in which the ventilation resistance in the open passage 62 is made larger than the ventilation resistance in the ventilation passage 60. In the configuration shown in FIG. 10, the open path 62 is provided with a filter 368 for suppressing the entry of foreign matter, and the ventilation path 60 is not provided with a filter 368.

As the filter 368, for example, PALL: Acro 25LCF10000 series is used.

According to the configuration shown in FIG. 10, a filter 368 is provided between the supply tank 44 and the open passage 62 in the ventilation passage 60 and between the recovery tank 45 and the open passage 62 in the ventilation passage 60. In comparison with the above, while suppressing the evaporation of ink water inside the supply tank 44, the ingress of foreign matter into the supply tank 44 and the recovery tank 45 is suppressed by a common filter. Further, in the configuration shown in FIG. 10, since the filter 368 serves as both the imparting member for imparting ventilation resistance and the suppressing member for suppressing the ingress of foreign matter, a dedicated member is used for each of the imparting member and the suppressing member. Compared to the case, the number of parts is reduced.

(Other variants)
In the present embodiment, the ejection mechanism 12 has been described as an example of an ejection device that ejects ink as a liquid from the ejection unit to a recording medium conveyed by the transport unit, but the present invention is not limited to this. For example, the inkjet recording device 10 may be grasped as an example of a ejection device that ejects ink as a liquid from the ejection unit to a recording medium conveyed by the transport unit. The ejection device may be, for example, a film forming apparatus that ejects a liquid to form a film, a 3D printer, or the like.

In the present embodiment, the open path 62 is used as an example of the open portion, but the present invention is not limited to this. For example, the opening portion may be an opening formed in the ventilation pipe 602 in which the ventilation passage 60 is formed.

In the present embodiment, ink is sent from the supply tank 44 to the recovery tank 45 via the discharge head 32Y due to the head difference of the liquid level of the supply tank 44 with respect to the liquid level of the recovery tank 45, but the present invention is not limited to this. For example, a pump may be used to send ink from the supply tank 44 to the recovery tank 45 via the discharge head 32Y.

The present invention is not limited to the above embodiment, and various modifications, changes, and improvements can be made without departing from the gist thereof. For example, the above-mentioned modified examples may be configured by combining a plurality of them as appropriate.

(evaluation)
The effect of this embodiment was evaluated using the evaluation device of FIG. 11 imitating the configuration of the comparative example shown in FIG. 3 and the evaluation device of FIG. 12 imitating the configuration of the present embodiment shown in FIG.

The evaluation device of FIG. 11 has a first tank 101 as a supply tank 44, a second tank 102 as a recovery tank 45, a liquid feed pipe 110, and a pump 112. The air chamber 103 of the first tank 101 and the air chamber 104 of the second tank 102 are each independently opened to the atmosphere. One end of the liquid feeding pipe 110 is inserted into the inside of the first tank 101 through the opening 101A of the first tank 101, and is arranged in a state of being immersed in the ink inside the first tank 101. The other end of the liquid feeding pipe 110 is inserted into the inside of the second tank 102 through the opening 102A of the second tank 102, and is arranged in a state of being immersed in the ink inside the second tank 102.

In the evaluation device of FIG. 12, the air chamber 103 of the first tank 101 and the air chamber 104 of the second tank 102 were connected by a ventilation pipe 190, and an open pipe 192 was connected to an intermediate portion of the ventilation pipe 190. Except for this point, the evaluation device of FIG. 12 is configured in the same manner as the evaluation device of FIG.

Then, in the evaluation devices of FIGS. 11 and 12, the pump 112 provided in the liquid feeding pipe 110 is driven to send a part of the ink of the first tank 101 to the second tank 102, and then the second tank 102. The operation of returning the ink from the first tank 101 to the first tank 101 was repeated. The evaluation was performed by measuring the water content (water evaporation rate) of the inks of the first tank 101 and the second tank 102, which decreased per unit time. The result is shown in FIG. In FIG. 13, the result of the evaluation device of FIG. 11 is A, and the result of the evaluation device of FIG. 12 is B. As shown in FIG. 13, the water evaporation rate of the evaluation device of FIG. 12 was 1/10 or less of the water evaporation rate of the evaluation device of FIG. That is, it was found that the evaporation of ink water was suppressed by connecting the air chamber 103 of the first tank 101 and the air chamber 104 of the second tank 102 with a ventilation pipe 190.

Further, in FIG. 13, the result when the ventilation resistance in the open pipe 192 is made larger than the ventilation resistance in the ventilation pipe 190 by using the open pipe 192 of 15 m is shown as C. Further, the result when the filter is provided in the open pipe 192 and the ventilation resistance in the open pipe 192 is made larger than the ventilation resistance in the ventilation pipe 190 is shown as D. The results C and D have a slower water evaporation rate than the result B. As described above, it was found that by increasing the ventilation resistance in the open pipe 192 rather than the ventilation resistance in the ventilation pipe 190, the evaporation of the water content of the ink is further suppressed.

10 Inkjet recording device (an example of image forming device)
12 Discharge mechanism (example of discharge device)
20 Transport mechanism (an example of transport unit)
32Y discharge head (example of discharge part)
42 Supply section 43 Recovery section 60 Ventilation path 62 Open path (example of open section)
150 Liquid transfer mechanism 153 Third air chamber 155 Storage tank (an example of storage unit)
368 Filter 441 First air chamber 452 Second air chamber

Claims (6)

The discharge part that discharges the liquid and
A supply unit that supplies the liquid stored inside to the discharge unit,
A collection unit that collects the liquid from the discharge unit and stores the liquid inside,
An air passage connecting a first air chamber formed on the liquid inside the supply section and a second air chamber formed on the liquid inside the recovery section.
An open portion that opens the ventilation path to the atmosphere,
A liquid feeding mechanism that sends liquid from the collecting unit to the supply unit,
Equipped with
The open portion is
The ventilation resistance to the supply part and the ventilation resistance to the recovery part in the ventilation passage are arranged at substantially the same intermediate position.
Discharge device. The liquid feeding mechanism is
It has a storage unit that stores the liquid sent from the collection unit and the liquid is sent to the supply unit.
The ventilation path is
The first air chamber, the second air chamber, and the third air chamber formed on the liquid inside the storage portion are connected to each other.
The discharge device according to claim 1. The ventilation resistance in the open portion is larger than the ventilation resistance in the ventilation passage.
The discharge device according to claim 1 or 2. The open portion is a passage narrower than the ventilation passage.
The discharge device according to claim 3. The open portion is provided with a filter for suppressing the entry of foreign matter, and the ventilation path is not provided with the filter.
The discharge device according to claim 3 or 4. A transport unit that transports recording media and
Due to the head difference between the supply unit and the collection unit, ink as a liquid is sent from the supply unit to the collection unit via the discharge unit, and the liquid feeding mechanism drives the ink from the collection unit to the supply unit. The ejection device according to any one of claims 1 to 5, wherein the ink is ejected from the ejection unit to the recording medium transported by the transport unit.
An image forming apparatus.

Images