JP2010214693A - Liquid circulation tank and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid circulation tank for efficiently venting air while maintaining a liquid circulation efficiency, and an image forming apparatus. <P>SOLUTION: Residual air is preferably vented to a C chamber through an air vent hole 110 with no resistance, when filtrating ink S from a B chamber to the C chamber in an ink sub-tank 100. The ink S is preferably closed not to make the ink S overflow into the C chamber through the air vent hole 110, after the ink S is sufficiently filled in the B chamber. The air vent hole 110 is selectively opened or closed according to the presence or absence of the ink S by a swelling resin member 101. The air vent hole 110 communicates the B chamber with the C chamber, because the swelling resin member 101 is not swelled under a dry state. The air vent hole 110 is closed, when the swelling resin member 101 absorbs the ink S, to be swollen. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid circulation tank and an image forming apparatus.

  Ink heads that have an ink circulation function for improving head temperature control and latency (responsiveness), the ink circulation efficiency is reduced due to air remaining in the tank when ink is filled, and ink purging by pressurization is performed. Even during maintenance, there was a problem that the pressure efficiency dropped due to air accumulation. In contrast, for example, in an ink jet recording apparatus, a configuration has been proposed in which air accumulation (bubbles) is prevented in a path from an ink tank to an ink flow path and a discharge port (nozzle).

  As an example, the nozzle part and ink supply path are formed using a temperature-sensitive liquid-absorbing resin (= a resin that absorbs and expands at low temperatures, but causes a phase transition and discharges and contracts when the temperature rises). However, a configuration of an ink jet printer that closes the nozzles to prevent ink evaporation during non-operation (at low temperatures) or absorbs ink in the entire flow path is disclosed (for example, see Patent Document 1).

  Also, in order to prevent the inflow of air to the ink jet recording head from the gap between the ink tank and the porous body that adjusts the ink supply pressure in the ink tank, the porous body is heated and swollen together with the ink tank, A configuration of an ink jet printer that closes a gap between a porous body and an ink tank is disclosed (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 06-126975 Japanese Patent Laid-Open No. 10-25999

  However, in the method described in Patent Document 1, the ink is heated by a heater provided in the head during operation, and the temperature-sensitive liquid absorbing resin discharges and contracts the ink so that the nozzle is opened and the ink can be ejected. Therefore, the structure is complicated, and heating of the ink is essential for the operation, and there is a concern of deterioration and evaporation. Further, it is not possible to positively remove bubbles inside the ink tank or in the vicinity of the nozzles.

  Further, the method described in Patent Document 2 also requires heating by a heater during operation, and is a configuration related to a single-use cartridge that is not premised on ink circulation, and is related to ink circulation and air bubbles generated in the apparatus. Is not disclosed.

  In view of the above facts, an object of the present invention is to provide a liquid circulation tank and an image forming apparatus capable of efficiently venting air while maintaining liquid circulation efficiency.

  According to the first aspect of the present invention, there is provided a substantially box-shaped tank main body, a liquid inflow port provided at an upper portion of the tank main body, and a liquid flowing out from the outside provided at an upper portion of the tank main body. A liquid outlet, a partition wall that divides the inside of the tank body between the liquid inlet and the liquid outlet, a liquid circulation path that is opened at a lower end of the partition wall, and an upper end of the partition wall An air vent hole that is open, and a swelling resin member that closes the air vent hole leaving a vent hole communicating with both sides of the partition wall and swells by contacting with the liquid and closes the vent hole. It is characterized by that.

  According to the above invention, since the air vent is open while the liquid level inside the tank body is low, the remaining air is efficiently ventilated from the liquid inlet side to the both sides of the partition wall during liquid filling or liquid purging. When the liquid level rises, the swellable resin member swells and closes the vent, so the liquid circulating in the tank body circulates through the liquid circulation path instead of the vent. Can be made.

  According to the second aspect of the present invention, there is provided a substantially box-shaped tank body, a liquid inlet provided at the upper part of the tank body, and a liquid flowing in from the outside. A liquid outlet, a partition wall that divides the inside of the tank body between the liquid inlet and the liquid outlet, a liquid circulation path that is opened at a lower end of the partition wall, and an upper end of the partition wall An air vent hole that is opened, and a swelling resin member that is provided between the liquid inlet and the air vent hole, swells or contracts in a direction to come in contact with or separate from the air vent hole, and closes the air vent hole when swollen. It is characterized by having.

  According to the above invention, the air vent hole is opened while the liquid level is low, and the remaining air is efficiently purged at the time of liquid filling or liquid purging. When the liquid level rises, the swellable resin member swells and the air vent hole is formed. Due to the blockage, the liquid circulating in the tank body can be circulated via the liquid circulation path instead of the air vent hole.

  According to a third aspect of the present invention, in the configuration of the second aspect, a plug member that fits into the air vent hole is provided at a tip of the swellable resin member.

  According to said invention, a swellable resin member swells, a plug member is fitted in an air vent hole, and is obstruct | occluded, and an air vent hole can be obstruct | occluded more reliably.

  According to a fourth aspect of the present invention, there is provided a substantially box-shaped tank main body, a liquid inflow port provided at an upper part of the tank main body, and a liquid flowing out from the outside provided at an upper part of the tank main body. A liquid outlet, a filter that divides the inside of the tank body between the liquid inlet and the liquid outlet, an air vent hole that is opened at an upper end of the filter, and a vent that communicates both sides of the filter And a swelling resin member that closes the air vent hole and swells by contacting with the liquid and closes the vent hole.

  According to said invention, while providing an air vent hole in the filter which divides the inside of a tank main body and making it obstruct | occlude with a swelling resin member, while venting efficiently, an air vent hole can be obstruct | occluded more reliably.

  According to a fifth aspect of the present invention, in the configuration according to any one of the first to fourth aspects, at least a part of the surface including the lowermost surface of the swellable resin member has water repellency. Features.

  According to the above invention, after the liquid level reaches the lower end of the swellable resin member, the swellable resin member does not swell until it reaches a height that exceeds the surface having water repellency. can do.

  A sixth aspect of the present invention is the liquid circulation tank according to any one of the first to fifth aspects, and a pressurizing chamber that is connected to the liquid circulation tank by a supply flow path and pressurizes the flow path liquid. And a droplet discharge head provided with an actuator for pressing the pressure chamber and a discharge nozzle for discharging the liquid pressurized in the pressure chamber as droplets.

  According to the invention described above, air can be vented efficiently while maintaining liquid circulation efficiency in the droplet discharge head.

  Since the present invention is configured as described above, it is possible to provide a liquid circulation tank and an image forming apparatus that can efficiently vent the air while maintaining the liquid circulation efficiency.

1 is a conceptual diagram illustrating a main part of an image forming apparatus according to an embodiment of the present invention. It is a figure which expands and shows the structure of the ink subtank concerning 1st Embodiment of this invention. It is a side view which expands and shows the structure of the head plate used for the inkjet line head which concerns on embodiment of this invention. FIG. 3 is an enlarged view showing a structure of an ink sub tank shown in FIG. 2. It is a figure which expands and shows the structure of the ink sub tank which concerns on 2nd Embodiment of this invention. It is a figure which expands and shows the structure of the ink subtank concerning 3rd Embodiment of this invention. It is a figure which expands and shows the structure of the ink sub tank which concerns on 4th Embodiment of this invention.

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

<Overall configuration>
As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment is provided with a paper feed conveyance unit 12 that feeds and conveys paper P on the upstream side in the conveyance direction of the paper P as a recording medium. An image is formed on the recording surface of the paper P on the recording surface of the paper P, and on the downstream side in the transport direction of the paper feeding / conveying unit 12, along the transport direction of the paper P An image forming unit 16, an image fixing unit 20 that fixes the dried image on the paper P, and a discharge unit 21 that discharges the paper P on which the image is fixed are sequentially provided. Hereinafter, each processing unit will be described.

<Paper feed section>
The paper feeding / conveying unit 12 is provided with a stacking unit 22 on which the sheets P are stacked, and the sheets P stacked on the stacking unit 22 are fed one by one downstream of the stacking unit 22 in the sheet conveying direction. A paper feeding unit 24 is provided. The paper P fed by the paper feeding unit 24 is transported to the processing liquid coating unit 14 via a transport unit 28 constituted by a plurality of roller pairs 26.

<Processing liquid application part>
In the treatment liquid application unit 14, a treatment liquid application drum 30 is rotatably disposed. The processing liquid coating drum 30 is provided with a holding member 32 that holds the paper P by sandwiching the leading end of the paper P, and the paper P is placed on the surface of the processing liquid coating drum 30 via the holding member 32. In the held state, the sheet P is conveyed downstream by the rotation of the treatment liquid coating drum 30.

  Note that an intermediate conveying drum 34, an image forming drum 36, and an image fixing drum 40, which will be described later, are also provided with a holding member 32 in the same manner as the processing liquid coating drum 30. The holding member 32 delivers the paper P from the upstream drum to the downstream drum.

  A processing liquid coating device 42 and a processing liquid drying device 44 are disposed on the upper portion of the processing liquid coating drum 30 along the circumferential direction of the processing liquid coating drum 30. The treatment liquid is applied to the recording surface, and the treatment liquid is dried by the treatment liquid drying device 44.

  Here, the treatment liquid reacts with the ink to aggregate the color material (pigment) and has an effect of promoting separation of the color material (pigment) and the solvent. The treatment liquid application device 42 is provided with a storage portion 46 in which the treatment liquid is stored, and a part of the gravure roller 48 is immersed in the treatment liquid.

  A rubber roller 50 is disposed in pressure contact with the gravure roller 48, and the rubber roller 50 contacts the recording surface (front surface) side of the paper P to apply the processing liquid. Further, a squeegee (not shown) is in contact with the gravure roller 48 to control the amount of treatment liquid applied to the recording surface of the paper P. In the treatment liquid drying apparatus 44, a hot air nozzle 54 and a heater 56 are disposed in the vicinity of the surface of the treatment liquid application drum 30. The sheet P on which the processing liquid has been applied to the recording surface and dried by the processing liquid application unit 14 is conveyed to an intermediate conveyance unit 58 provided between the processing liquid application unit 14 and the image forming unit 16.

<Intermediate transport section>
An intermediate transport drum 58 is rotatably provided in the intermediate transport unit 58, and the leading end of the paper P is held on the surface of the intermediate transport drum 34 via a holding member 32 provided in the intermediate transport drum 34. The sheet P is transported downstream by the rotation of the intermediate transport drum 34.

<Image forming unit>
An image forming drum 36 is rotatably provided in the image forming unit 16, and the sheet P is held on the surface of the image forming drum 36 via a holding member 32 provided on the image forming drum 36 to form an image. The sheet P is conveyed downstream by the rotation of the drum 36.

  Above the image forming drum 36, a head unit 66 composed of a single-pass inkjet line head 64 is disposed in the vicinity of the outer peripheral surface of the image forming drum 36. In this head unit 66, for example, YMCK inkjet line heads 64, which are basic colors, are arranged along the circumferential direction of the image forming drum 36, and an image is formed on the paper P with droplets of each color.

  The inkjet line head 64 determines droplet landing positions with high accuracy by ejecting liquid droplets in synchronization with an encoder (not shown) that detects the rotational speed disposed on the image forming drum 36, and at the same time, the image forming drum. The droplet discharge unevenness can be reduced without depending on the shake of 36, the accuracy of the rotating shaft 68, and the drum surface speed.

  The head unit 66 can be retracted from the upper part of the image forming drum 36, and maintenance operations such as cleaning of the nozzle surface of the inkjet line head 64 and discharging of the thickened ink are performed on the head unit 66 at the upper part of the image forming drum 36. It may be configured to be implemented by evacuating.

  The sheet P on which the image is formed on the recording surface is transported to an intermediate transport unit 70 provided between the image forming unit 16 and the ink drying unit 18 by the rotation of the image forming drum 36. Since the configuration is substantially the same as that of the intermediate conveyance unit 58, description thereof is omitted.

<Ink drying section>
A drying drum 38 is rotatably provided in the ink drying unit 18, and a plurality of hot air nozzles 72 and IR heaters 74 are disposed on the top of the drying drum 38 in the vicinity of the surface of the ink drying unit 18. ing.

  Here, as an example, the pair of IR heaters 74 arranged in parallel with the hot air nozzles 72 are alternately arranged so that the hot air nozzles 72 are arranged on the upstream side and the downstream side. In addition to this, a large number of IR heaters 74 are arranged on the upstream side to irradiate a large amount of heat energy on the upstream side to increase the temperature of moisture, and a large number of hot air nozzles 72 are arranged on the downstream side to blow off saturated water vapor. Also good.

  Here, the hot air nozzle 72 is arranged so that the blowing angle of the hot air is inclined toward the rear end side of the paper. As a result, the flow of hot air from the hot air nozzle 72 can be collected in one direction, and the sheet can be pressed against the drying drum 38 and the sheet can be held on the surface of the drying drum 38.

  With the hot air generated by the hot air nozzle 72 and the IR heater 74, the solvent separated by the color material aggregating action is dried in the paper image forming unit, and a thin image layer is formed.

  Although the warm air varies depending on the paper conveyance speed, it is usually set to 50 ° C. to 70 ° C., and the ink surface temperature is set to 50 ° C. to 60 ° C. by setting the temperature of the IR heater 74 to 200 ° C. to 600 ° C. It is set to be. The evaporated solvent is discharged together with air to the outside of the image forming apparatus 10, but the air is recovered. This air may be cooled by a cooler / radiator or the like and recovered as a liquid.

  The sheet on which the image on the recording surface has been dried is conveyed to the intermediate conveyance unit 76 provided between the ink drying unit 18 and the image fixing unit 20 by the rotation of the drying drum 38. Since the configuration is substantially the same as that of the transport unit 58, description thereof is omitted.

<Image fixing unit>
An image fixing drum 40 is rotatably provided in the image fixing unit 20. In the image fixing unit 20, latex particles in a thin image layer formed on the paper P are heated / pressurized and melted. And has a function of fixing and fixing on the paper P.

  A heating roller 78 is disposed above the image fixing drum 40 in the vicinity of the surface of the image fixing drum 40. The heating roller 78 has a halogen lamp incorporated in a metal pipe made of aluminum or the like having a good thermal conductivity. The heating roller 78 applies heat energy equal to or higher than the Tg temperature of the latex. As a result, the latex particles are melted and pressed into the irregularities on the paper P for fixing, and the irregularities on the surface of the image are smoothed to obtain glossiness.

  A fixing roller 80 is provided on the downstream side of the heating roller 78. The fixing roller 80 is disposed in pressure contact with the surface of the image fixing drum 40 so as to obtain a nip force with the image fixing drum 40. I have to. Therefore, at least one of the fixing roller 80 and the image fixing drum 40 has an elastic layer on the surface and a uniform nip width with respect to the paper P.

  After the above steps, the paper P on which the image on the recording surface is fixed is conveyed to the discharge unit 21 provided on the downstream side of the image fixing unit 20 by the rotation of the image fixing drum 40.

  Although the image fixing unit 20 has been described in the present embodiment, the image fixing unit 20 may be configured to dry and fix the image formed on the recording surface by the drying drum 38, and the image fixing unit 20 is not necessarily essential.

<Structure of droplet discharge head>
An ink jet line head according to an embodiment of the present invention includes the droplet discharge head shown in FIGS.

  As shown in FIG. 2A, the ink sub-tank 100 having a substantially rectangular parallelepiped hollow box shape includes a head plate 104 in the ejection direction (lower side in the figure), and ink in the opposite ejection direction (upper side in the figure). An inlet 106 and an ink outlet 108 are provided to allow ink to flow into and out of the inside.

  As shown in FIG. 2B, the interior of the ink sub-tank 100 formed by the box body 111 is divided into two by a partition wall 102, and an ink inlet chamber 116 communicating with the ink inlet 106, an ink outlet chamber 108, It is divided into an ink outlet chamber 118 that communicates.

  An air vent hole 110 is formed between the upper end of the partition wall 102 and the box body 111 without reaching the inner side of the box body 111. In addition, the lower end of the partition wall 102 does not reach the inside of the box body 111, and the circulation channel 114 is formed between the box body 111 and the lower end of the partition wall 102.

  As shown in FIG. 2C, the ink inlet chamber 116 and the ink outlet chamber 118 are both vertically divided by a filter 112, and the ink S flowing from the ink inlet 106 passes through the circulation channel 114 or the air vent hole 110. When it passes through and flows into the ink outlet chamber 118, it is filtered by the filter 112. Similarly, the ink S flowing into the ink outlet chamber from the ink inlet chamber 116 is again filtered by the filter 112 before being discharged from the ink outlet 108. That is, the ink S that has flowed in from the ink inlet 106 is filtered by the filter 112 as in the A chamber → B chamber in the figure, and then passes through the circulation channel 114 (or the air vent hole 110) and again as in the C chamber → D chamber. Filtered by the filter 112.

  As shown in FIG. 2D, the air vent hole 110 is formed between the upper end of the partition wall 102 and the box body 111, and the swellable resin member 101 is formed on the upper end of the partition wall 102 so as to cover it. Is provided. The swellable resin member 101 covers the air vent hole 110 leaving the vent 103.

  As a material of the swellable resin member 101, for example, a nylon resin, a swelling gel (a nitrile rubber modified with butyl acrylate is swollen with methyl ethyl ketone), or the like can be used. Moreover, as a structure which swells with organic solvents, such as alcohol, acrylic synthetic resin is mention | raise | lifted as swelling resin. Or you may select from a silicone resin, an epoxy resin, an acrylic resin, etc.

  The swellable resin member 101 is, for example, covered with a water repellent surface 101B on the surface except for the upper end, and the ink S is not absorbed by the swellable resin member 101 until the liquid level of the ink S reaches the upper end of the swellable resin member 101. It is said that.

  FIG. 3 shows a structural example of the inkjet line head 64. As shown in FIG. 3B, an ink sub-tank 100 is provided on the plate 104 and includes a supply channel 210 through which ink S is supplied from an ink tank (not shown) via an ink inlet 106. The ink S filtered by the ink sub tank 100 is supplied to the supply flow path 210 from the liquid circulation port 216. A plurality of the plates 104 and the ink sub-tanks 100 are arranged in the width direction of the paper P, and each ejects the ink S as droplets.

  As shown in FIG. 3A, in the head plate 104, a pressure chamber 212 to which ink S is supplied from a supply flow path 210, a nozzle 214 for discharging the ink S pressurized in the pressure chamber 212 as droplets, and a pressure chamber A vibration plate 200 that presses 212 and presses the ink S, a piezoelectric body 202 that drives the vibration plate 200, a drive wiring 204 that applies an electric signal to each piezoelectric body, and a voltage that is provided to each nozzle 214 from a drive wiring. Individual electrodes 206 to be connected, connection terminals 208 for electrically connecting the drive wiring 204 to the outside of the head plate 104, and a common electrode (not shown) provided between the diaphragm 200 and the piezoelectric body 202 and grounded (0V). An insulating layer (not shown) provided between the common electrode and the drive wiring 204 to electrically insulate them is provided.

<Effects of First Embodiment>
FIG. 4 shows the structure near the air vent hole of the ink sub-tank according to the first embodiment of the present invention.

  As shown in FIG. 4A, when the ink S is filtered from the B chamber shown in FIG. 2C to the C chamber in the ink sub-tank 100, the residual air passes through the air vent hole 110 (vent hole 103). It is desirable to pass through to room C without resistance. Further, after the ink S is sufficiently filled in the B chamber, it is desirable to block the ink S so as not to overflow into the C chamber through the air vent hole 110 (vent hole 103). Therefore, in this embodiment, the air vent hole 110 (vent hole 103) is selectively opened or closed by the swellable resin member 101 depending on the presence or absence of the ink S.

  That is, since the swelling resin member 101 is not swollen while being dried, the air vent hole 110 (vent hole 103) communicates the B chamber and the C chamber. When the swellable resin member 101 absorbs the ink S and swells, the air vent hole 110 (vent hole 103) is closed.

 After the ink S is filled into the B chamber and the air is removed into the C chamber, the air vent hole 110 is closed, and if the ink S is injected from the ink inlet 106, it passes through the circulation channel 114 opened at the lower end of the partition wall 102. The ink S flows into the C chamber, and the temperature control near the head plate 104 by the ink S can be performed efficiently.

  Alternatively, when air accumulates in the ink sub-tank 100 over time, such as when air bubbles are mixed into the supplied ink S or when air is sucked in from the nozzle 214 due to the deterioration of the ink discharge state, the swellable resin member 101 is removed. Since the ink S does not come into contact, the ink S contained in the swellable resin member 101 gradually decreases.

  For this reason, the expansion amount of the swellable resin member 101 is reduced (the outer dimensions are reduced), and the air vent hole 110 (vent hole 103) is opened again so that air can be vented, so that the accumulated air can be excluded into the C chamber.

 Further, the shape of the vent 103 that opens when not swollen (during drying) may be a slit or a circle as shown in FIG. 4 (C), or as shown in FIG. 4 (D). Although it may be a rectangular shape or other shapes, it is desirable to have a rectangular shape in order to provide a wide opening at a high position in the ink sub tank 100 as much as possible.

  Further, as shown in FIG. 2D, for example, when the surface of the swellable resin member 101 is covered with the water-repellent surface 101B except for the upper end portion, the liquid level of the ink S is on the upper end of the swellable resin member 101. Since the ink S is not absorbed by the swellable resin member 101 until it reaches, the swellable resin member 101 does not swell and the air vent hole 110 (vent hole 103) is maintained open, and the ink S is swelled. The ink S is absorbed by the swellable resin member 101 from the portion not covered by the water repellent surface 101B, and the swelling occurs and the vent 103 is closed.

  Thus, since the swellable resin member 101 does not block the air vent hole 110 until the liquid level of the ink S reaches a desired height (the upper end of the swellable resin member 101), the air vent is completely discharged until the air is completely discharged into the C chamber. It can be set as the structure which does not prevent 103 ventilation | gas_flowing.

  The water-repellent surface 101B does not necessarily have to be formed up to the vicinity of the upper end of the swellable resin member 101. By forming the water-repellent surface 101B up to a desired position, the water repellent surface 101B can swell at any timing and close the vent 103.

<Second Embodiment>
FIG. 5 shows the structure near the air vent hole of the ink sub-tank according to the second embodiment of the present invention.

  As shown in FIG. 5A, an air vent hole 110 is provided at the upper end of the partition wall 102 that partitions the inside of the ink sub-tank 100 between the box body 111 and the second embodiment.

  A swellable resin member 101 </ b> C is fitted in the air vent hole 110. The swellable resin member 101 </ b> C has a hollow and substantially pipe shape, and one or a plurality of vent holes 103 are opened to ensure ventilation of the air vent hole 110. A convex portion 111A is provided on the inner wall of the box body 111 facing the partition wall 102, and the swellable resin member 101C is clamped from the outside together with the partition wall 102 to be positioned.

  Similar to the first embodiment, the swellable resin member 101C also swells when it comes into contact with the ink S as the ink level rises, and closes the air vent hole 110 by closing the vent 103. Yes.

  Further, a plurality of vent holes 103 may be provided as shown in FIGS. 5B and 5D, and a plurality of small diameter vent holes 103 are provided to easily block the swelling of the swellable resin member 101C. It may be set as a structure.

  The hole diameter and shape of the vent 103 may be different from each other, for example. For example, since the swellable resin member 101C swells as the liquid level of the ink S rises, the vent 103 near the upper end may be enlarged, and the opening of the air vent hole 110 may be secured even after the swelling starts.

<Third Embodiment>
FIG. 6 shows the structure near the air vent hole of the ink sub tank according to the third embodiment of the present invention.

  As shown in FIG. 6A, the air vent hole 110 is provided between the upper end of the partition wall 102 that partitions the inside of the ink sub tank 100 and the box body 111 as in the first embodiment.

  A swellable resin member 101D is fitted in the air vent hole 110. The swellable resin member 101D has a hollow and substantially pipe shape, and the vent 103 is opened to ensure ventilation of the air vent hole 110. The periphery of the vent 103 has a check valve structure, and when closed, air can flow out from the B chamber to the C chamber according to the internal pressure.

  Further, a convex portion 111A is provided on the inner wall of the box body 111 facing the partition wall 102, and the swellable resin member 101D is sandwiched from the outside together with the partition wall 102 and positioned.

  Similarly to the first embodiment, the swellable resin member 101D also swells when it comes into contact with the ink S as the ink level rises, and closes the air vent hole 110 by closing the vent 103. Yes.

  Further, since the vent 103 has a check valve structure as described above, the internal pressure of the B chamber can be sufficiently increased even after the liquid level of the ink S rises and the vent 103 is closed. For example, the remaining air can be pumped to the C chamber through the vent 103. On the other hand, the air is prevented from flowing back into the B room even if the pressure in the C room is high.

<Fourth embodiment>
FIG. 7 shows the structure near the air vent hole of the ink sub-tank according to the fourth embodiment of the present invention.

  As shown in FIG. 7A, the air vent hole 110 is provided at the upper end of the partition wall 102 that divides the interior of the ink sub-tank 100 between the box body 111 and the second embodiment.

  In this embodiment, the swellable resin member is not fitted in the air vent hole 110, and a support portion 111B is provided at a position facing the air vent hole 110 in the B room, and the swellable resin member 101 is placed on the support portion 111B. Is provided. At the tip of the swellable resin member 101, a plug member 105 that fits into the air vent hole 110 and closes it is provided.

  The plug member 105 corresponds to the shape of the air vent hole 110. For example, if the air vent hole 110 is a round hole, a conical shape is used, and if it is a square hole, the air vent hole 110 can be closed without gaps. Also good.

  When the liquid level of the ink S rises in the B chamber, the swellable resin member 101 swells in a direction approaching the air vent hole 110 by contacting the ink S, and urges the plug member 105 toward the air vent hole 110. . As a result, the air vent hole 110 is blocked by the plug member 105, and the ink S can be prevented from leaking into the C chamber.

  Further, as shown in FIG. 7B, the plug member 105 is provided as a curved plate-like member so that the outside of the curved surface is joined to the partition wall 102 near the air vent hole 110, and the swellable resin member 101 is provided inside the curved surface. May be provided. The plug member 105 has a thermal expansion coefficient substantially equal to that of the swellable resin member 101 and is formed of a material that does not swell with the ink S.

  According to this configuration, as the liquid level of the ink S rises, the swellable resin member 101 absorbs the ink S and swells, and urges the plug member 105 in a direction to expand the curved surface outward while expanding. As shown in C), the plug member 105 is deformed into a planar shape, and the air vent hole 110 can be closed.

  As described above, the air vent hole 110 provided in the partition wall 102 is closed by the swellable resin member 101 that absorbs and swells the ink S, so that the air remains in the ink sub tank 100. The air vent hole 110 can be blocked so that the ink S does not pass if the liquid level of the ink S rises while the discharged air is efficiently discharged. Therefore, for example, when the temperature of the head plate 104 is adjusted by circulation of the ink S, the ink S passes through the liquid circulation path 114, so that the temperature can be adjusted efficiently. Further, the backflow of impurities such as dust mixed in the ink S can be prevented.

<Others>
As mentioned above, although the Example of this invention was described, it cannot be overemphasized that this invention is not limited to said Example at all, and can implement in a various aspect in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the configuration in which the sheet P is held and transported on the surface of the drum has been described as an example. However, the present invention is not limited to this. For example, a configuration using an endless belt-shaped transport belt or a flat plate stage is used. It is also possible to apply the present invention to a configuration for carrying.

  In the above-described embodiment, the processing liquid is applied to the paper P by the processing liquid application unit 14 and dried, and then droplets are ejected to the paper P by the head unit 66. Of course, the present invention is not limited to this. For example, the present invention can be applied to a normal inkjet printer that holds normal paper (plain paper) and conveys it as it is, and directly ejects liquid droplets on the surface to form an image. .

  Furthermore, the discharged liquid is not limited to ink, and may be applied to, for example, substrate pattern formation during etching.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Paper feed conveyance part 14 Processing liquid application part 16 Image formation part 18 Ink drying part 20 Image fixing part 21 Discharge part 34 Intermediate conveyance drum 36 Image formation drum 38 Drying drum 38 Drying drum 40 Image fixing drum 64 Inkjet Line head 66 Head unit 100 Ink sub tank (tank body)
101 Swellable resin member 101B Water repellent surface 102 Partition wall 103 Vent hole 104 Head plate 105 Plug member 106 Ink inlet (liquid inlet)
108 Ink outlet (liquid outlet)
110 Air vent hole 111 Box body 112 Filter 114 Circulation flow path 116 Ink inlet chamber 118 Ink outlet chamber P Paper S Ink

Claims (6)

An approximately box-shaped tank body,
A liquid inlet provided at the top of the tank body and into which liquid flows from the outside;
A liquid outlet that is provided at the top of the tank body and from which the liquid flows out to the outside;
A partition wall dividing the inside of the tank body between the liquid inlet and the liquid outlet;
A liquid circulation path opened at a lower end of the partition wall;
An air vent hole opened at the upper end of the partition wall;
A swelling resin member that closes the air vent hole leaving a vent communicating with both sides of the partition wall, swells by contacting with the liquid and closes the vent;
Liquid circulation tank equipped with. An approximately box-shaped tank body,
A liquid inlet provided at the top of the tank body and into which liquid flows from the outside;
A liquid outlet that is provided at the top of the tank body and from which the liquid flows out to the outside;
A partition wall dividing the inside of the tank body between the liquid inlet and the liquid outlet;
A liquid circulation path opened at a lower end of the partition wall;
An air vent hole opened at the upper end of the partition wall;
A swelling resin member that is provided between the liquid inlet and the air vent hole, swells or contracts in a direction contacting and leaving the air vent hole, and closes the air vent hole when swollen;
Liquid circulation tank equipped with. The liquid circulation tank according to claim 2, wherein a plug member that fits into the air vent hole is provided at a tip of the swellable resin member. An approximately box-shaped tank body,
A liquid inlet provided at the top of the tank body and into which liquid flows from the outside;
A liquid outlet that is provided at the top of the tank body and from which the liquid flows out to the outside;
A filter that divides the interior of the tank body between the liquid inlet and the liquid outlet;
An air vent hole opened at the upper end of the filter;
A swollen resin member that closes the vent hole leaving the vent communicating with both sides of the filter, swells by contacting with the liquid, and closes the vent;
Liquid circulation tank equipped with. The liquid circulation tank according to any one of claims 1 to 4, wherein at least a part of the surface including the lowermost surface of the swellable resin member has water repellency. The liquid circulation tank according to any one of claims 1 to 5,
A pressurizing chamber connected to the liquid circulation tank by a supply flow path and pressurizing the flow path liquid;
An actuator for pressurizing the pressurizing chamber;
A discharge nozzle for discharging the liquid pressurized in the pressure chamber as droplets;
An image forming apparatus provided with a droplet discharge head provided with

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