JPWO2017061265A1 - Inkjet recording device - Google Patents

Abstract

An ink jet recording apparatus capable of suppressing unintentional leakage of ink from a nozzle of a recording head is provided. An ink jet recording apparatus includes a recording head provided with a nozzle for discharging ink, an ink storage unit for storing ink supplied to the recording head, an ink storage unit, and a flow path unit provided in the recording head and communicating with the nozzle. An ink circulation path through which the ink circulates, and a liquid feeding means for applying a pressure to the ink in the ink circulation path to flow and supplying the ink in the ink storage unit to the recording head by the liquid feeding operation And a first liquid supply control for causing the liquid supply means to perform a liquid supply operation at a first pressure at which ink is discharged from the nozzles by supplying ink to the flow path portion of the recording head, and smaller than the first pressure. A control unit that performs a second liquid feeding control that causes the liquid feeding unit to perform a liquid feeding operation at a second pressure at which the ink is not discharged from the nozzles by supplying ink to the flow path part of the recording head. , Comprising a.

Description

  The present invention relates to an ink jet recording apparatus.

  2. Description of the Related Art Conventionally, there is an ink jet recording apparatus that records an image on a recording medium by ejecting ink to the recording medium from a plurality of nozzles provided in the recording head. The ink jet recording apparatus has an ink circulation path that passes through an ink storage section that stores ink supplied to the recording head and the recording head, and operates a pump (liquid feeding means) provided in the ink circulation path to operate the ink. In some cases, the ink can be supplied from the ink reservoir to the recording head and the ink can be collected from the recording head to the ink reservoir (for example, Patent Document 1).

  In such an ink jet recording apparatus, a valve is provided in an ink recovery path through which ink recovered from the recording head to the ink reservoir passes in the ink circulation path, and the liquid feeding means is in a state where the ink circulation path is closed by the valve. By performing the liquid feeding, the pressure maintenance operation for forcibly discharging the ink fed to the recording head from the nozzles and eliminating the clogging of the nozzles is performed. In addition, by performing liquid feeding by the liquid feeding means in a state where the ink circulation path is opened by the valve, an ink supply operation for supplying ink from the ink reservoir to the recording head, or ink in the recording head to the ink reservoir A reflux maintenance operation is performed in which the bubbles contained in the ink are removed by refluxing. In this way, by performing liquid feeding by switching between opening and closing of the ink circulation path, various maintenance operations and ink supply operations can be performed using the liquid feeding means with a fixed liquid feeding amount.

JP 2013-86438 A

  However, the above conventional technique has a problem that unintentional leakage of ink from the nozzles occurs when ink is supplied to the recording head depending on the amount of liquid fed by the liquid feeding means.

  An object of the present invention is to provide an ink jet recording apparatus capable of suppressing unintended leakage of ink from nozzles of a recording head.

In order to achieve the above object, the invention of the ink jet recording apparatus according to claim 1 comprises:
A recording head provided with nozzles for ejecting ink;
An ink storage section for storing ink supplied to the recording head;
An ink circulation path through which the ink stored in the ink storage section circulates through the ink storage section and a flow path section provided in the recording head and communicating with the nozzle;
A liquid feeding operation in which a pressure is applied to the ink in the ink circulation path to cause the ink to flow in a predetermined liquid feeding direction, and the ink in the ink reservoir is supplied to the recording head by the liquid feeding operation. Means,
A first liquid feeding control for causing the liquid feeding means to perform the liquid feeding operation at a first pressure at which ink is discharged from the nozzles by supplying ink to the flow path portion of the recording head; and A second liquid feeding control for causing the liquid feeding means to perform the liquid feeding operation at a second pressure at which the ink is not discharged from the nozzles by supplying ink to the flow path portion of the recording head smaller than the pressure. Control means to perform;
It is characterized by having.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
Switching means provided in a range from the recording head to the ink reservoir in the liquid feeding direction in the ink circulation path to open or close the ink circulation path;
The liquid feeding means performs the liquid feeding operation by applying pressure to ink at a position from the ink reservoir to the recording head in the liquid feeding direction in the ink circulation path,
The control means performs the first liquid feeding control in a state where the ink circulation path is closed by the switching means, and the second liquid feeding control in a state where the ink circulation path is opened by the switching means. It is characterized by performing.

The invention according to claim 3 is the ink jet recording apparatus according to claim 2,
The switching means has a first valve that opens or closes in response to an input of a predetermined drive signal to open or close the ink circulation path,
The control means controls opening and closing of the first valve.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect,
The first valve is an electromagnetic valve.

The invention according to claim 5 is the ink jet recording apparatus according to claim 2,
The switching means is closed by the pressure of the ink when the pressure of the ink related to the liquid feeding operation is equal to or higher than a predetermined reference pressure that is smaller than the first pressure and larger than the second pressure. A second valve for closing
When the first liquid feeding control is performed, the control unit causes the liquid feeding unit to perform the liquid feeding operation at a pressure equal to or higher than the reference pressure, and closes the second valve.

A sixth aspect of the present invention is the ink jet recording apparatus according to the fifth aspect,
The second valve is
A tube portion having a converging portion that passes ink flowing by the liquid feeding operation and becomes thinner toward the downstream side in the liquid feeding direction;
When the pressure of the ink passing through the tube portion by the liquid feeding operation is equal to or higher than the reference pressure, the stopper portion moves in the tube portion in the liquid feeding direction by the pressure of the ink and closes the converging portion;
It is characterized by having.

  According to the present invention, there is an effect that unintentional leakage of ink from the nozzles of the recording head can be suppressed.

It is a figure which shows schematic structure of an inkjet recording device. It is the schematic of an internal structure at the time of seeing a head unit from the side. It is the schematic of an internal structure at the time of seeing a head unit from the conveyance drum side. It is a side view of a recording head. It is a schematic diagram which shows the structure of an ink supply mechanism. It is a block diagram which shows the main function structures of an inkjet recording device. It is a figure explaining discharge maintenance operation. It is a figure explaining reflux maintenance operation and ink supply operation. It is a flowchart which shows the control procedure of a pressurization maintenance process. It is a flowchart which shows the control procedure of a reflux maintenance process and an ink supply process. It is a flowchart which shows the control procedure of an image recording process. It is a schematic cross section which shows the structure of an automatic shut-off valve. It is a schematic cross section which shows the structure of the automatic shut-off valve of a closed state.

(First embodiment)
Hereinafter, a first embodiment according to an ink jet recording apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention.
The ink jet recording apparatus 1 includes a paper feeding unit 10, an image recording unit 20, a paper discharge unit 30, and a control unit 40 (FIG. 5). Under the control of the control unit 40, the inkjet recording apparatus 1 conveys the recording medium M stored in the paper feeding unit 10 to the image recording unit 20, and the image recording unit 20 forms an image on the recording medium M. The formed recording medium M is conveyed to the paper discharge unit 30.
As the recording medium M, in addition to paper such as plain paper and coated paper, various media capable of fixing ink landed on the surface, such as cloth or sheet-like resin, can be used.

  The paper supply unit 10 includes a paper supply tray 11 that stores the recording medium M, and a medium supply unit 12 that conveys and supplies the recording medium M from the paper supply tray 11 to the image recording unit 20. The medium supply unit 12 includes a ring-shaped belt supported on the inside by two rollers, and the recording medium M is removed from the paper feed tray 11 by rotating the roller while the recording medium M is placed on the belt. It is conveyed to the image recording unit 20.

  The image recording unit 20 includes a transport drum 21, a delivery unit 22, a heating unit 23, a head unit 24, a fixing unit 25, a delivery unit 26, and the like.

The transport drum 21 has a cylindrical surface, and the outer peripheral surface thereof is a transport surface 21 a on which the recording medium M is placed. The conveyance drum 21 rotates around a rotation axis extending in a direction (X direction) perpendicular to the drawing of FIG. 1 while holding the recording medium M on the conveyance surface 21a, thereby moving the recording medium M along the conveyance surface. It transports in the transport direction (Y direction). The transport drum 21 includes a claw portion and a suction portion (not shown) for holding the recording medium M on the transport surface 21a. The recording medium M is held on the conveyance surface 21a by the end being pressed by the claw portion and sucked to the conveyance surface by the intake portion.
The transport drum 21 is connected to a transport drum motor (not shown) for rotating the transport drum 21 and rotates by an angle proportional to the rotation amount of the transport drum motor.

  The delivery unit 22 delivers the recording medium M conveyed by the medium supply unit 12 of the paper supply unit 10 to the conveyance drum 21. The delivery unit 22 is provided at a position between the medium supply unit 12 and the conveyance drum 21 of the paper supply unit 10, and picks up one end of the recording medium M conveyed from the medium supply unit 12 by the swing arm unit 221. Then, it is delivered to the transport drum 21 through the delivery drum 222.

  The heating unit 23 is provided between the arrangement position of the transfer drum 222 and the arrangement position of the head unit 24, and the recording medium M conveyed by the conveyance drum 21 has a temperature within a predetermined temperature range. Heat M. The heating unit 23 includes, for example, an infrared heater, and energizes the infrared heater based on a control signal supplied from the CPU 41 (FIG. 5) to cause the heater to generate heat.

  The head unit 24 forms an image by ejecting ink to the recording medium M at an appropriate timing according to the rotation of the transport drum 21 on which the recording medium M is held based on the image data. The head unit 24 is disposed with a predetermined distance between the ink discharge surface and the transport drum 21. In the ink jet recording apparatus 1 of the present embodiment, four head units 24 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are transported in the recording medium M. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side.

  2A and 2B are diagrams showing an internal configuration of the head unit 24. FIG. FIG. 2A is a schematic diagram of the internal configuration when the head unit 24 is viewed from the side. FIG. 2B is a schematic diagram of the internal configuration when the head unit 24 is viewed from the transport drum 21 side. The case where the head unit 24 is viewed from the side refers to the case where the head unit 24 is viewed from a direction parallel to the transport direction of the recording medium M at a position facing the head unit 24 on the transport surface 21a.

  The head unit 24 supplies a plurality of recording heads 241 each provided with a plurality of recording elements that eject ink, a first storage unit 242 that stores ink supplied to the recording head 241, and a first storage unit 242. A second storage portion 243 for storing the ink to be stored. Each of the plurality of recording elements includes a pressure chamber for storing ink, a piezoelectric element provided on a wall surface of the pressure chamber, and a nozzle 2411. Among these, the nozzle 2411 ejects ink from an opening provided on the ink ejection surface of the recording head 241 facing the conveyance surface 21 a of the conveyance drum 21. In the recording head 241, a plurality of nozzles 2411 are arranged in two rows in the X direction to form two nozzle rows, and these two nozzle rows are only one-half of the arrangement interval of the nozzles 2411 in the X direction. They are arranged in a state shifted from each other.

  In the head unit 24, as shown in FIG. 2B, a pair of recording heads 241 adjacent to each other in the Y direction are arranged in a staggered manner at different positions in the X direction. With such an arrangement of the recording head 241, the arrangement range in the X direction of the nozzles 2411 included in the head unit 24 is the width in the X direction of an area where an image can be formed in the recording medium M conveyed by the conveying drum 21. It comes to cover. The head unit 24 is used with its position fixed with respect to the rotation axis of the transport drum 21 during image recording. That is, the inkjet recording apparatus 1 is an inkjet recording apparatus that performs single-pass image recording using a line head.

  The head unit 24 is provided so as to be movable in the X direction between a position facing the transport drum 21 and a position facing a cleaning unit (not shown). Under the control of the control unit 40, the head unit 24 moves to a position facing the conveyance drum 21 when performing image recording, and moves to a position facing the cleaning unit when performing pressure maintenance described later. Here, the cleaning unit includes an ink receiving unit that receives ink ejected from the head unit 24 during pressure maintenance.

  Each head unit 24 includes a recording head drive unit 51 (FIG. 5) that drives the recording head 241. The recording head driving unit 51 includes a driving circuit that supplies a voltage signal having a driving waveform corresponding to image data to each recording head 241, and a driving control circuit that supplies image data to the driving circuit at an appropriate timing. . When a voltage signal having a driving waveform for deforming the piezoelectric element is applied to the piezoelectric element from the driving circuit of the recording head driving unit 51, the pressure in the pressure chamber changes according to the voltage signal, and the nozzle communicates with the pressure chamber. Ink is discharged from.

FIG. 3 is a side view of the recording head 241 and is an enlarged view of one recording head 241 in FIG. 2A.
The recording head 241 is supplied to the upper flow path portion 2412 and the lower flow path portion 2413 (flow path portion), the upper flow path portion 2412 and the lower flow path portion 2413 that function as ink flow paths in the recording head 241. A supply portion 2414 that is a flow passage of the ink, a discharge portion 2415 that is a flow passage of ink discharged from the upper flow passage portion 2412 and the lower flow passage portion 2413. Among these, the upper flow path portion 2412 and the lower flow path portion 2413 communicate with the nozzle 2411 through the pressure chamber.

  A portion of the ink flowing from the supply unit 2414 into the upper flow path unit 2412 flows into the lower flow path unit 2413 through the filter 2416 that filters the ink. The ink supplied from the supply unit 2414 flows through the upper channel unit 2412 and the lower channel unit 2413 and is ejected from the plurality of nozzles 2411 by the ink ejection operation by the recording element, or is forcibly generated by the ink feeding pressure. 2411 is discharged. Further, the ink flowing through the upper flow path portion 2412 and the lower flow path portion 2413 can also flow out from the discharge portion 2415.

As the ink ejected from the nozzles 2411 of the head unit 24, ink having a property of changing in phase to a gel or sol depending on temperature and being cured by irradiating energy rays such as ultraviolet rays is used.
In this embodiment, ink that is gel-like at room temperature and becomes sol-like when heated is used. The head unit 24 includes an ink heating unit (not shown) that heats the ink stored in the head unit 24, and the ink heating unit operates under the control of the CPU 41 and heats the ink to a sol-like temperature. . The recording head 241 discharges ink that has been heated to form a sol. When the sol-like ink is ejected onto the recording medium M, the ink droplets land on the recording medium M, and then naturally cool to solidify on the recording medium M by being naturally cooled.

  The fixing unit 25 has a light emitting unit arranged over the width of the transport drum 21 in the X direction, and irradiates the recording medium M placed on the transport drum 21 with energy rays such as ultraviolet rays from the light emitting unit. Then, the ink discharged on the recording medium M is cured and fixed. The light emitting unit of the fixing unit 25 is arranged to face the conveyance surface 21a on the downstream side of the arrangement position of the head unit 24 and the upstream side of the arrangement position of the delivery drum 261 of the delivery unit 26 in the conveyance direction.

  The delivery unit 26 includes a belt loop 262 having a ring-shaped belt supported on the inside by two rollers, and a cylindrical delivery drum 261 that delivers the recording medium M from the transport drum 21 to the belt loop 262. The recording medium M transferred from the transfer drum 21 onto the belt loop 262 by the transfer drum 261 is transferred by the belt loop 262 and sent to the paper discharge unit 30.

  The paper discharge unit 30 includes a plate-shaped paper discharge tray 31 on which the recording medium M sent from the image recording unit 20 by the delivery unit 26 is placed.

  Next, an ink supply mechanism that supplies ink to the recording head 241 in the inkjet recording apparatus 1 will be described.

FIG. 4 is a schematic diagram illustrating the configuration of the ink supply mechanism 300.
In FIG. 4, a portion related to one recording head 241 of the ink supply mechanism 300 is extracted and shown. In FIG. 4, the ink and gas paths are indicated by broken lines or chain lines.

  The ink supply mechanism 300 includes a second storage unit 243 (ink storage unit) that stores ink supplied to the recording head 241, a first storage unit 242 that stores ink supplied from the second storage unit 243, and a first storage unit 242. 2 Ink tank 244 that stores ink supplied to the storage unit 243, a supply path 301 that serves as an ink passage, a recovery path 302, an inter-storage unit path 303, and an exhaust pump that exhausts air in the first storage unit 242 P2, the ventilation path 306, the 1st electromagnetic valve 307 (switching means, 1st valve), the 2nd electromagnetic valve 308, the 3rd electromagnetic valve 309, etc. are provided.

  The first storage unit 242 is connected to the supply unit 2414 of the recording head 241 via the supply path 301. The second storage unit 243 is connected to the discharge unit 2415 of the recording head 241 via the recovery path 302. The supply path 301 and the recovery path 302 may be provided with a heater for heating the ink passing therethrough to a temperature within a predetermined range.

Moreover, the 1st storage part 242 and the 2nd storage part 243 are connected via the path | route 303 between storage parts. The inter-reservoir path 303 is provided with a liquid feed pump P1 (liquid feed means). The liquid feeding pump P1 applies a pressure to the ink in the inter-reservoir path 303 to perform a liquid feeding (liquid feeding operation) that causes the ink to flow in the direction from the second reservoir 243 toward the first reservoir 242. 2 The ink stored in the storage unit 243 is supplied to the first storage unit 242. The configuration of the liquid feeding pump P1 is not particularly limited. For example, a volume transfer type pump such as a diaphragm pump or a tube pump that feeds liquid by squeezing a tube with a roller can be used. Further, in the present embodiment, a pump in which the liquid feeding pressure is variable is used. The liquid feed pump P1 operates under the control of the control unit 40.
An ink circulation path that circulates ink by the first storage section 242, the supply path 301, the upper flow path section 2412 and the lower flow path section 2413 of the recording head 241, the recovery path 302, the second storage section 243, and the inter-storage section path 303. Is configured.

  The second storage unit 243 is connected to the ink tank 244 via the path 304. A pump (not shown) is provided in the path 304, and ink in the ink tank 244 is supplied to the second storage unit 243 according to the operation of the pump.

  The supply path 301, the recovery path 302, the inter-reservoir path 303, and the path 304 are tube-shaped members that allow ink to pass through, and are made of, for example, resins such as fluororesin and epoxy resin, and various metals.

  Further, the first storage unit 242 is connected to the exhaust pump P <b> 2 via the air passage 306. The exhaust pump P <b> 2 exhausts the air in the first reservoir 242 to generate a negative pressure in the first reservoir 242, thereby causing the ink in the supply path 301 and the recording head 241 to move toward the first reservoir 242. The ink is pulled in and the pressure of the ink in the nozzle 2411 is set to a negative pressure state. This prevents ink leakage from the nozzle 2411 when various maintenance is not performed or when an image is recorded. The air passage 306 is a tube-shaped member through which air passes, and can be formed of, for example, various resins or metals. The exhaust pump P2 operates under the control of the control unit 40.

  The recovery path 302 is provided with a first electromagnetic valve 307. Accordingly, the first electromagnetic valve 307 is within the range from the recording head 241 to the second storage portion 243 in the liquid feeding direction in the ink circulation path (position on the downstream side of the recording head 241 and the upstream side of the second storage portion 243). Is provided. In addition, a second electromagnetic valve 308 is provided between the second reservoir 243 and the liquid feed pump P1 in the inter-reservoir path 303. In addition, a third electromagnetic valve 309 is provided in the air passage 306. The first solenoid valve 307, the second solenoid valve 308, and the third solenoid valve 309 are opened and closed in accordance with a drive signal input from the solenoid valve drive unit 54, whereby the recovery path 302, the inter-reservoir path 303, and the ventilation are respectively opened. The opening and closing of the path 306 are switched.

  The first storage section 242 is a sealed container except for the connection points with the supply path 301, the storage section path 303, and the ventilation path 306. That is, the pressure in the first storage unit 242 varies depending on the negative pressure generated by the exhaust pump P2, the presence / absence of ink supply from the second storage unit 243, and the like. On the other hand, the second storage unit 243 is a container opened to the outside, and is maintained at substantially atmospheric pressure regardless of increase or decrease in the amount of ink.

  In FIG. 4, a portion related to one recording head 241 is extracted from the ink supply mechanism 300, but ink is supplied to the other recording heads 241 by the same mechanism. Here, the first storage unit 242, the supply path 301, the recovery path 302, the liquid feed pump P1, the first electromagnetic valve 307, the second electromagnetic valve 308, and the third electromagnetic valve 309 are provided in each of the plurality of recording heads 241. Correspondingly, or each two or more predetermined number of recording heads 241 are provided. The second storage unit 243, the ink tank 244, and the exhaust pump P2 are provided one by one in the inkjet recording apparatus 1.

FIG. 5 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.
In addition to the heating unit 23, the head unit 24, and the fixing unit 25 described above, the inkjet recording apparatus 1 includes a control unit 40, a transport drive unit 52, a head unit movement drive unit 53, an electromagnetic valve drive unit 54, and a liquid feed. A pump drive unit 55, an exhaust pump drive unit 56, an operation display unit 57, an input / output interface 58, a bus 59, and the like are provided. Among these, the control unit 40 includes a CPU 41 (Central Processing Unit) (control means), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

  The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, executes the programs, and performs various arithmetic processes. The CPU 41 controls the overall operation of the inkjet recording apparatus 1. For example, the CPU 41 operates each unit of the image recording unit 20 based on the image data stored in the storage unit 44 to record an image on the recording medium M. The CPU 41 operates each part of the ink supply mechanism 300 to supply ink to the recording head 241 and to perform various maintenance operations.

  The RAM 42 provides a working memory space to the CPU 41 and stores temporary data. The RAM 42 stores data indicating the setting of the liquid pump pressure. The RAM 42 may include a nonvolatile memory.

  The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like. In place of the ROM 43, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

  The storage unit 44 stores a print job (image recording command) input from the external apparatus 2 via the input / output interface 58 and image data related to the print job. As the storage unit 44, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

  The transport drive unit 52 supplies a drive signal to the transport drum motor of the transport drum 21 based on a control signal supplied from the CPU 41 to rotate the transport drum 21 at a predetermined speed and timing. Further, the transport drive unit 52 supplies a drive signal to a motor for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 26 based on a control signal supplied from the CPU 41 to transport the recording medium M. Supply to the drum 21 and discharge from the transport drum 21 are performed.

  The head unit movement drive unit 53 outputs a drive signal to a motor (not shown) based on a control signal supplied from the CPU 41, and the head unit 24 is positioned at a position facing the transport drum 21 and a position facing the cleaning unit. Move in the X direction.

  The solenoid valve drive unit 54 outputs drive signals to the first solenoid valve 307, the second solenoid valve 308, and the third solenoid valve 309 based on the control signal supplied from the CPU 41, whereby the first solenoid valve 307, the second electromagnetic valve 308 and the third electromagnetic valve 309 are opened and closed independently.

  The liquid feed pump drive unit 55 supplies a drive signal to the liquid feed pump P1 based on the control signal supplied from the CPU 41, and causes the liquid feed pump P1 to feed ink at the liquid feed pressure indicated by the control signal. .

  The exhaust pump drive unit 56 supplies a drive signal to the exhaust pump P2 based on a control signal supplied from the CPU 41, and causes the exhaust pump P2 to exhaust the air in the first storage unit 242.

  The operation display unit 57 includes a display device such as a liquid crystal display and an organic EL display, and an input device such as a touch panel and operation keys arranged on the screen of the display device. The operation display unit 57 displays various information on the display device, converts a user input operation to the input device into an operation signal, and outputs the operation signal to the control unit 40.

  The input / output interface 58 mediates data transmission / reception between the external device 2 and the control unit 40. The input / output interface 58 is configured by, for example, one of various serial interfaces, various parallel interfaces, or a combination thereof.

  The bus 59 is a path for transmitting and receiving signals between the control unit 40 and other components.

  The external device 2 is a personal computer, for example, and supplies a print job, image data, and the like to the control unit 40 via the input / output interface 58.

  Next, a pressure maintenance operation, a reflux maintenance operation, an ink supply operation, and an image recording operation performed in the ink jet recording apparatus 1 will be described.

The discharge maintenance operation is performed for the purpose of eliminating clogging of the nozzle 2411 by pressurizing the ink in the recording head 241 and forcibly discharging the ink from the nozzle 2411.
The purpose of the reflux maintenance operation is to remove the air bubbles contained in the ink in the recording head 241 from the recording head 241 by causing the ink in the recording head 241 to flow back to the second reservoir 243. The ink bubbles removed from the inside of the recording head 241 are released under the atmospheric pressure by being swept away by the second reservoir 243 and disappear.
The ink supply operation is performed for the purpose of supplying ink used for image recording from the first storage unit 242 to the recording head 241.
In the image recording operation, an image is recorded by ejecting ink from each head unit 24 to the recording medium M at an appropriate timing according to the conveyance of the recording medium M by the conveying drum 21.
The discharge maintenance operation, the reflux maintenance operation, and the ink supply operation can be performed individually for each recording head 241 or for each head unit 24. Further, it may be performed simultaneously on a plurality of recording heads 241 or a plurality of head units 24.

FIG. 6 is a diagram for explaining the discharge maintenance operation.
The discharge maintenance operation is performed in a state where the head unit 24 has moved to a position facing the cleaning unit.
In the discharge maintenance operation, the first electromagnetic valve 307 and the third electromagnetic valve 309 are closed and the liquid supply pump P1 supplies liquid with the second electromagnetic valve 308 opened. As a result, the ink stored in the second storage unit 243 is supplied to the first storage unit 242 and the pressure in the first storage unit 242 rises, and the ink in the first storage unit 242 is caused to increase by the pressure. To the upper flow path portion 2412 and the lower flow path portion 2413. Here, the liquid feeding pressure by the liquid feeding pump P1 is a first pressure at which the ink supplied to the recording head 241 is forcibly discharged from the nozzle 2411 by the liquid feeding pressure. In this way, the ink is discharged from the nozzle 2411, so that the clogging of the nozzle 2411 can be eliminated.
When the discharge of ink from the nozzle 2411 is started and a predetermined time has elapsed, the liquid feeding by the liquid feeding pump P1 is stopped, and the ink stored in the first storage unit 242 flows back to the second storage unit 243. To prevent this, the second solenoid valve 308 is closed. In this state, the electromagnetic valve 307 is opened to open the collection path 302, and the ink discharge in the recording head 241 is reduced, whereby the ink discharge is stopped. In the discharge maintenance operation, the time for discharging the ink from the nozzle 2411 is, for example, about 1 to 3 [seconds].

FIG. 7 is a diagram for explaining the reflux maintenance operation and the ink supply operation.
The reflux maintenance operation and the ink supply operation can be performed in a state where the head unit 24 is moved to a position facing the conveyance surface 21a of the conveyance drum 21, but can also be performed in a state where the head unit 24 is moved to a position opposed to the cleaning unit. good.
In the reflux maintenance operation and the ink supply operation, the first electromagnetic valve 307 and the second electromagnetic valve 308 are opened, and the liquid feeding pump P1 performs the liquid feeding with the third electromagnetic valve 309 closed. Thereby, the ink stored in the second storage unit 243 circulates through the first storage unit 242, the supply path 301, the upper flow path part 2412 and the lower flow path part 2413 of the recording head 241, and the recovery path 302, and Ink is supplied to the recording head 241. Here, the pressure of the liquid feeding by the liquid feeding pump P1 is a second pressure at which the ink supplied to the recording head 241 is not discharged from the nozzle 2411 due to the pressure of the liquid feeding. Therefore, the second pressure is smaller than the first pressure in the pressurization maintenance operation. In addition, in the reflux maintenance process, the time during which the liquid feeding pump P1 performs the liquid feeding is a time necessary for sufficiently removing the ink bubbles by the return of the ink to the second reservoir 243, and the ink supply In the processing, the time required for supplying a sufficient amount of ink to the recording head 241 is set.

Next, an image recording operation will be described.
In the image recording operation, the first electromagnetic valve 307 and the second electromagnetic valve 308 are closed and the third electromagnetic valve 309 is opened, and the air in the first storage unit 242 is exhausted by the exhaust pump P2 to be the first storage. By making the inside of the section 242 have a negative pressure, the ink in the supply path 301 and the recording head 241 is drawn toward the first storage section 242, and the pressure in the nozzle 2411 is slightly negative. In this state, the conveyance of the recording medium M by the conveyance drum 21 is started, and an image is recorded on the recording medium M by ejecting ink from the nozzles 2411 at an appropriate timing according to the conveyance.

Next, processing performed by the CPU 41 in the pressurization maintenance operation, the reflux maintenance operation, the ink supply operation, and the image recording operation will be described with reference to flowcharts.
The discharge maintenance process and the reflux maintenance process are started when a predetermined input operation is performed by the user on the operation display unit 57 or when a predetermined condition relating to the operation of the inkjet recording apparatus 1 is satisfied. Examples of the case where the predetermined condition is satisfied include a case where an image is formed on a recording medium M having a predetermined amount or more, a case where a predetermined time has elapsed since the last image recording operation, and the like. The image recording process is executed when a print job and image data are input from the external device 2 to the control unit 40 via the input / output interface 58. Further, the ink supply operation is performed before or after the execution of the image recording operation when a predetermined amount or more of ink is ejected by the head unit 24 since the last ink supply operation.

FIG. 8 is a flowchart showing the control procedure of the pressurization maintenance process.
When the pressurization maintenance process is started, the CPU 41 outputs a control signal to the head unit movement driving unit 53 to move the head unit 24 to a position facing the cleaning unit.

  When the pressurization maintenance process is started, the CPU 41 causes the first solenoid valve 307, the second solenoid valve 308, and the third solenoid valve 309 to output drive signals from the solenoid valve drive unit 54, and the first solenoid valve 307 and The third electromagnetic valve 309 is closed and the second electromagnetic valve 308 is opened (step S11).

  The CPU 41 sets the liquid feeding pressure of the liquid feeding pump P1 to the first pressure, and stores data related to the setting in the RAM 42 (step S12).

  The CPU 41 starts ink feeding by the liquid feeding pump P1 (step S13: first liquid feeding control). That is, the CPU 41 outputs a drive signal from the liquid feed pump drive unit 55 to the liquid feed pump P1 by outputting a control signal to the liquid feed pump drive unit 55 based on the setting of the liquid feed pressure stored in the RAM 42. The liquid feeding pump P1 causes ink to be fed at the first pressure.

  The CPU 41 outputs a control signal to the liquid feed pump drive unit 55 to stop the liquid feed by the liquid feed pump P1 when a predetermined time has elapsed from the start of ink liquid feed (step S14), and the electromagnetic valve drive unit. The drive signal is output from the control signal 54 to the second electromagnetic valve 308 to close the second electromagnetic valve 308 (step S15).

  The CPU 41 outputs a drive signal from the electromagnetic valve drive unit 54 to the first electromagnetic valve 307 to open the first electromagnetic valve 307, and then closes the first electromagnetic valve 307 when a predetermined time has elapsed (step S16). Thereafter, the CPU 41 outputs a drive signal from the solenoid valve drive unit 54 to the third solenoid valve 309 to open the third solenoid valve 309 (step S17), and finishes the pressurization maintenance process.

FIG. 9 is a flowchart showing a control procedure of the reflux maintenance process and the ink supply process.
When the reflux maintenance process or the ink supply process is started, the CPU 41 outputs a control signal to the head unit movement driving unit 53 to move the head unit 24 to a position facing the conveyance surface 21 a of the conveyance drum 21.

  When the reflux maintenance process or the ink supply process is started, the CPU 41 causes the first solenoid valve 307, the second solenoid valve 308, and the third solenoid valve 309 to output drive signals from the solenoid valve driving unit 54, and the first solenoid valve 309 is output. The valve 307 and the second electromagnetic valve 308 are opened, and the third electromagnetic valve 309 is closed (step S21).

  The CPU 41 sets the liquid supply pressure of the liquid supply pump P1 to the second pressure, and stores data related to the setting in the RAM 42 (step S22).

  The CPU 41 starts ink feeding by the liquid feeding pump P1 (step S23: second liquid feeding control). That is, the CPU 41 outputs a drive signal from the liquid feed pump drive unit 55 to the liquid feed pump P1 by outputting a control signal to the liquid feed pump drive unit 55 based on the setting of the liquid feed pressure stored in the RAM 42. The liquid feeding pump P1 causes ink to be fed at the second pressure.

  The CPU 41 outputs a control signal to the liquid feed pump drive unit 55 to stop the liquid feed by the liquid feed pump P1 when a predetermined time has elapsed since the start of ink feeding (step S24). Here, the predetermined time is a time required for the ink bubbles to be sufficiently removed by the return of the ink to the second reservoir 243 in the reflux maintenance process, and the recording head 241 is used in the ink supply process. This is the time required for supplying a sufficient amount of ink.

The CPU 41 outputs drive signals from the solenoid valve driving unit 54 to the first solenoid valve 307, the second solenoid valve 308, and the third solenoid valve 309, closes the first solenoid valve 307 and the second solenoid valve 308, and The electromagnetic valve 309 is opened (step S25).
When the process of step S25 ends, the CPU 41 ends the reflux maintenance process or the ink supply process.

FIG. 10 is a flowchart showing the control procedure of the image recording process.
When the image recording process is started, the CPU 41 outputs a control signal to the head unit movement driving unit 53 to move the head unit 24 to a position facing the conveyance surface 21 a of the conveyance drum 21.

  When the image recording process is started, the CPU 41 causes the first electromagnetic valve 307, the second electromagnetic valve 308, and the third electromagnetic valve 309 to output drive signals from the electromagnetic valve driving unit 54, and the first electromagnetic valve 307 and the first electromagnetic valve 307 are output. The second electromagnetic valve 308 is closed and the third electromagnetic valve 309 is opened (step S31).

  The CPU 41 generates a negative pressure in the first reservoir 242 and the recording head 241 by the exhaust pump P2 (step S32). That is, the CPU 41 outputs a control signal from the exhaust pump drive unit 56 to the exhaust pump P2 by outputting a control signal to the exhaust pump drive unit 56, and the exhaust pump P2 causes the first storage unit 242 and the recording head 241 to operate. A negative pressure of a predetermined value is generated at.

The CPU 41 causes the head unit 24 to record an image on the recording medium M (step S33). That is, the CPU 41 outputs a control signal to the conveyance driving unit 52 and rotates the conveyance drum 21 by the conveyance driving unit 52 to convey the recording medium M. Then, the CPU 41 supplies a control signal including image data to the recording head driving unit 51, and outputs a voltage signal having a driving waveform to the recording head 241 by the recording head driving unit 51 at an appropriate timing according to the rotation of the transport drum 21. By outputting, ink is ejected from the nozzles 2411 of the head unit 24 onto the recording medium M conveyed by the conveying drum 21 to record a part of the image on the recording medium M. In addition, the CPU 41 outputs a control signal to the transport driving unit 52 to operate the delivery unit 26, and discharges the recording medium M on which an image is recorded to the paper discharge unit 30.
When the process of step S33 ends, the CPU 41 ends the image recording process.

(Modification)
In the above-described embodiment, a configuration may be adopted in which ink is collected in the second reservoir 243 through different paths from the upper flow path portion 2412 and the lower flow path portion 2413 of the recording head 241. That is, in addition to the discharge part 2415 from which the ink flows out from the upper flow path part 2412, a bypass part from which the ink flows from the lower flow path part 2413 is provided, and is connected to the first recovery path connected to the discharge part 2415 and the bypass part. The second recovery path may be joined to one common recovery path and connected to the second storage unit 243. In this case, an electromagnetic valve is provided in each of the first recovery path and the second recovery path, and only one of the first recovery path and the second recovery path is opened by these electromagnetic valves when ink is fed in the reflux maintenance. By doing so, it is possible to perform the reflux maintenance for one of the upper flow path portion 2412 and the lower flow path portion 2413.

  As described above, the inkjet recording apparatus 1 according to the present embodiment includes the recording head 241 provided with the nozzles 2411 that eject ink, the second storage unit 243 that stores the ink supplied to the recording head 241, and the second storage unit 243. An ink circulation path through which the ink stored in the second storage section 243 circulates through the storage section 243, the upper flow path section 2412 and the lower flow path section 2413 provided in the recording head 241 and communicating with the nozzle 2411; A liquid feeding pump that applies a pressure to the ink in the circulation path to cause the ink to flow in a predetermined liquid feeding direction, and supplies the ink in the second reservoir 243 to the recording head 241 by the liquid feeding operation. Ink is discharged from the nozzle 2411 by supplying ink to P1 and the upper flow path portion 2412 and the lower flow path portion 2413 of the recording head 241. The first liquid supply control for causing the liquid supply pump P1 to perform the liquid supply operation at the pressure of the ink, and the ink by supplying the ink to the upper flow path portion 2412 and the lower flow path portion 2413 of the recording head 241 smaller than the first pressure. Is provided with a CPU 41 (control means) that performs a second liquid feeding control for causing the liquid feeding pump P1 to perform a liquid feeding operation at a second pressure that is not discharged from the nozzle 2411. According to such a configuration, the pressurization maintenance operation can be performed by the first liquid feeding control, and the reflux maintenance operation and the ink supply operation can be performed by the second liquid feeding control. In the second liquid feeding control, since the liquid feeding operation is performed at the second pressure at which the ink is not discharged from the nozzle 2411, unintentional leakage of ink from the nozzle 2411 of the recording head 241 can be suppressed. Thereby, wasteful consumption of ink can be suppressed, and contamination of each part of the inkjet recording apparatus 1 due to leakage of ink can be suppressed.

  In addition, the inkjet recording apparatus 1 includes a first electromagnetic valve 307 that is provided in a range from the recording head 241 to the second reservoir 243 in the liquid feeding direction in the ink circulation path to open or close the ink circulation path. The liquid feed pump P1 performs a liquid feed operation by applying pressure to the ink at a position from the second reservoir 243 to the recording head 241 in the liquid feed direction in the ink circulation path, and the CPU 41 includes the first electromagnetic valve. The first liquid feeding control is performed in a state where the ink circulation path is closed by 307, and the second liquid feeding control is performed in the state where the ink circulation path is opened by the first electromagnetic valve 307 (control means). Accordingly, since the recovery path 302 is closed by the first electromagnetic valve 307 in the pressurization maintenance operation, the liquid feed pump P1 can perform the liquid feed at the first pressure more efficiently.

  The first electromagnetic valve 307 opens and closes in response to the input of a predetermined drive signal to open or close the ink circulation path, and the CPU 41 controls the opening and closing of the first electromagnetic valve 307 (control means). Thereby, the opening and closing of the ink circulation path by the first electromagnetic valve 307 can be easily switched.

  In addition, by using the electromagnetic valve (first electromagnetic valve 307), the ink circulation path can be switched between opening and closing at high speed.

(Second Embodiment)
Next, a second embodiment according to the ink jet recording apparatus of the present invention will be described.
In the second embodiment, instead of the first electromagnetic valve 307, an automatic closing valve (switching means, second valve) that automatically closes according to the ink feeding pressure is used. Different from the embodiment. Hereinafter, differences from the first embodiment will be described.

11A and 11B are schematic cross-sectional views showing the configuration of the automatic closing valve 310.
The automatic closing valve 310 is provided in place of the first electromagnetic valve 307 at the arrangement position of the first electromagnetic valve 307 in FIG. 1 (that is, on the recovery path 302).

As shown in FIG. 11A, the automatic shut-off valve 310 includes a tube portion 3101 that allows ink to pass through the recovery path 302, a fixing member 3102 provided inside the tube portion 3101, and a liquid feed of ink from the fixing member 3102. An elastic member 3103 attached to the downstream side in the direction and a plug portion 3104 attached to the opposite side of the elastic member 3103 to the fixing member 3102 side are provided. As the elastic member 3103, for example, a spring or an elastic resin can be used. The tube portion 3101 has a funnel-shaped portion (converging portion) that becomes thinner toward the downstream side in the ink feeding direction. The plug portion 3104 is a point in the tube portion 3101 where the force in the liquid feeding direction received from the ink flowing in the tube portion 3101 and the force in the opposite direction to the liquid feeding direction received from the elastic member 3103 are balanced. To position. Then, when the pressure of the ink passing through the tube portion 3101 is higher than or equal to a predetermined reference pressure by liquid feeding by the liquid feeding pump P1, the plug portion 3104 feeds the inside of the pipe portion 3101 as shown in FIG. 11B. The funnel-shaped portion of the tube portion 3101 is closed by moving in the direction. Thus, the automatic closing valve 310 automatically closes the recovery path 302 in accordance with the ink feeding pressure.
Here, the reference pressure is set to a value smaller than the first pressure and larger than the second pressure. Therefore, when liquid supply at the first pressure is performed in the pressurization maintenance operation, the automatic shut-off valve 310 is closed and the recovery path 302 is closed. In addition, when liquid feeding is performed at the second pressure in the reflux maintenance operation and the ink supply process, since the tube portion 3101 is not blocked by the plug portion 3104, the automatic shutoff valve 310 is maintained open.

  After the automatic shut-off valve 310 is closed, ink is discharged from the nozzles 2411 according to the ink pressure in the recording head 241, whereby the ink pressure applied to the plug portion 3104 decreases. When the pressure falls below the reference pressure, the plug portion 3104 is pulled away from the tube portion 3101 by the elastic force received from the elastic member 3103, the blockage is released, and the recovery path 302 is opened.

  The pressurization maintenance process of this embodiment is equivalent to the pressurization maintenance process according to the first embodiment shown in FIG. 8 in which the process related to the first electromagnetic valve in steps S11 and S16 is omitted. Further, when ink feeding at the first pressure is started in step S13, the automatic shut-off valve 310 is closed, the recovery path 302 is closed, and the ink is forcibly discharged from the nozzle 2411 of the recording head 241. . When ink feeding is completed in step S14, the automatic closing valve 310 is opened as described above, the ink pressure in the recording head 241 is reduced, and the discharge of ink from the nozzle 2411 is stopped. Note that before the ink feeding at the first pressure in Step S13 is started, the automatic closing valve 310 may be closed by feeding the ink at a pressure higher than the reference pressure and lower than the first pressure. .

  Further, in the reflux maintenance process and the ink supply process of the present embodiment, the process related to the first electromagnetic valve in steps S21 and S25 in the reflux maintenance process and the ink supply process according to the first embodiment shown in FIG. 9 is omitted. It corresponds to a thing. In the reflux maintenance process and the ink supply process of the present embodiment, the automatic closing valve 310 is maintained in the open state even if the ink is supplied at the second pressure in step S23. In the same manner as described above, the ink is returned to the second storage unit 243 and the ink is supplied to the recording head 241.

  Note that the method of releasing the blockage of the tube portion 3101 by the plug portion 3104 of the automatic shutoff valve 310 is not limited to the method of discharging ink from the nozzle 2411 as described above. For example, the blockage may be released by discharging the ink through a bypass path other than the nozzle 2411 and lowering the pressure of the ink. Further, the blockage may be released by causing the ink to flow backward by the liquid feed pump P1. In addition, a fine opening that penetrates the plug portion 3104 in the ink feeding direction is provided, and after the tube portion 3101 is closed by the plug portion 3104, the ink pressure is lowered by flowing ink from the opening in the liquid feeding direction. It is also possible to release the blockage.

  As described above, in the ink jet recording apparatus 1 according to the second embodiment, when the pressure of the ink related to the liquid feeding operation is equal to or higher than the predetermined reference pressure that is smaller than the first pressure and larger than the second pressure. An automatic shut-off valve 310 that closes the ink circulation path by being closed by the pressure of the liquid is used, and the CPU 41 supplies liquid at a pressure higher than the reference pressure by the liquid supply pump P1 when performing liquid supply control related to the pressurization maintenance operation. To close the automatic shut-off valve 310 (control means). By using the automatic shut-off valve 310 in this way, electrical wiring for opening and closing the valve is not required, and the ink jet recording apparatus 1 can be reduced in cost and size, and the processing by the CPU 41 is simplified. be able to.

  Further, the automatic closing valve 310 allows the ink flowing through the liquid feeding operation to pass therethrough, and the pressure of the ink passing through the pipe portion 3101 by the pipe feeding portion 3101 having the converging part that becomes narrower toward the downstream in the liquid feeding direction. And a plug portion 3104 that moves in the tube portion 3101 in the liquid feeding direction by the pressure of the ink and closes the converging portion when the pressure is equal to or higher than the reference pressure. Thereby, the small automatic shut-off valve 310 of a simple structure is realizable.

Note that the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made.
For example, in each of the above-described embodiments and the modified examples, the first electromagnetic valve 307 or the automatic closing valve 310 is closed and the recovery path 302 is closed, and the pressure maintenance is performed. It is not the purpose. For example, without supplying a valve in the ink circulation path or in a state where all the valves provided in the ink circulation path are opened, the liquid supply pump P1 supplies ink at the second pressure to perform the circulation maintenance operation. The pressurization maintenance operation may be performed by performing the ink supply operation and performing the liquid supply by the liquid supply pump P1 at a pressure at which the ink is forcibly discharged from the nozzle 2411 larger than the second pressure.

  In each of the above embodiments and modifications, an electromagnetic valve has been described as an example of a valve that opens and closes in response to a drive signal. However, instead of this, another valve such as an electric valve that opens and closes a valve by the operation of a motor. May be used.

  In each of the above-described embodiments and modifications, the example in which the negative pressure in the recording head 241 is generated by the exhaust pump P2 in the image recording operation has been described. However, the negative pressure generation method is not limited to this. For example, the position of the recording head 241 may be made higher than the position of the ink level in the first storage unit 242 and the second storage unit 243 to generate the negative pressure due to the water head difference.

  In addition to the components shown in the above embodiments and modifications, other components that allow ink to pass may be provided on the ink circulation path that circulates the ink.

  In each of the above-described embodiments and modifications, the inkjet recording apparatus 1 that records an image using a line head in which the nozzles 2411 are arranged over the recording range of the image in the X direction on the recording medium M has been described as an example. The present invention may be applied to an ink jet recording apparatus that records an image while scanning the recording head.

  Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, and includes the scope of the invention described in the claims and equivalents thereof. .

  The present invention can be used in an ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 External apparatus 10 Paper feed part 11 Paper feed tray 12 Medium supply part 20 Image recording part 21 Conveyance drum 21a Conveyance surface 22 Delivery unit 23 Heating part 24 Head unit 25 Fixing part 26 Delivery part 30 Paper discharge part 31 Paper tray 40 control unit 41 CPU
42 RAM
43 ROM
44 Storage unit 51 Recording head drive unit 52 Transport drive unit 53 Head unit movement drive unit 54 Solenoid valve drive unit 55 Liquid feed pump drive unit 56 Exhaust pump drive unit 57 Operation display unit 58 Input / output interface 59 Bus 241 Recording head 2411 Nozzle 2412 Upper flow path part 2413 Lower flow path part 2414 Supply part 2415 Discharge part 2416 Filter 242 First storage part 243 Second storage part 244 Ink tank 300 Ink supply mechanism 301 Supply path 302 Recovery path 303 Inter-storage part path 304 Path 306 Ventilation path 307 1st solenoid valve 308 2nd solenoid valve 309 3rd solenoid valve 310 Automatic shut-off valve 3101 Pipe part 3102 Fixing member 3103 Elastic member 3104 Plug part M Recording medium P1 Liquid feed pump P2 Exhaust pump

Claims (6)

A recording head provided with nozzles for ejecting ink;
An ink storage section for storing ink supplied to the recording head;
An ink circulation path through which the ink stored in the ink storage section circulates through the ink storage section and a flow path section provided in the recording head and communicating with the nozzle;
A liquid feeding operation in which a pressure is applied to the ink in the ink circulation path to cause the ink to flow in a predetermined liquid feeding direction, and the ink in the ink reservoir is supplied to the recording head by the liquid feeding operation. Means,
A first liquid feeding control for causing the liquid feeding means to perform the liquid feeding operation at a first pressure at which ink is discharged from the nozzles by supplying ink to the flow path portion of the recording head; and A second liquid feeding control for causing the liquid feeding means to perform the liquid feeding operation at a second pressure at which the ink is not discharged from the nozzles by supplying ink to the flow path portion of the recording head smaller than the pressure. Control means to perform;
An ink jet recording apparatus comprising: Switching means provided in a range from the recording head to the ink reservoir in the liquid feeding direction in the ink circulation path to open or close the ink circulation path;
The liquid feeding means performs the liquid feeding operation by applying pressure to ink at a position from the ink reservoir to the recording head in the liquid feeding direction in the ink circulation path,
The control means performs the first liquid feeding control in a state where the ink circulation path is closed by the switching means, and the second liquid feeding control in a state where the ink circulation path is opened by the switching means. The inkjet recording apparatus according to claim 1, wherein: The switching means has a first valve that opens or closes in response to an input of a predetermined drive signal to open or close the ink circulation path,
The inkjet recording apparatus according to claim 2, wherein the control unit controls opening and closing of the first valve.   The inkjet recording apparatus according to claim 3, wherein the first valve is an electromagnetic valve. The switching means is closed by the pressure of the ink when the pressure of the ink related to the liquid feeding operation is equal to or higher than a predetermined reference pressure that is smaller than the first pressure and larger than the second pressure. A second valve for closing
The control means, when performing the first liquid feeding control, causes the liquid feeding means to perform the liquid feeding operation at a pressure equal to or higher than the reference pressure and closes the second valve. Item 3. The ink jet recording apparatus according to Item 2. The second valve is
A tube portion having a converging portion that passes ink flowing by the liquid feeding operation and becomes thinner toward the downstream side in the liquid feeding direction;
When the pressure of the ink passing through the tube portion by the liquid feeding operation is equal to or higher than the reference pressure, the stopper portion moves in the tube portion in the liquid feeding direction by the pressure of the ink and closes the converging portion;
The inkjet recording apparatus according to claim 5, comprising:

Images