JPWO2015098220A1 - Ink jet recording apparatus and control method thereof - Google Patents

Abstract

A degassing module 831 provided in the middle of the ink supply path, a vacuum pump 832 for depressurizing ink through a gas permeable membrane of the degassing module, and a vacuum pump provided between the degassing module and the vacuum pump. An atmosphere release valve 834 that can be switched between a connection state with the deaeration module and an atmosphere release state, and a control device 9 that controls the liquid feed pump, the vacuum pump, and the atmosphere release valve are provided. Pump drying control is performed to operate the vacuum pump with the valve open to the atmosphere.

Description

  The present invention relates to an ink jet recording apparatus provided with a deaeration device for ink supplied to a head and a control method thereof.

In an inkjet recording apparatus that pressurizes ink and ejects it from the nozzle, if the gas dissolved in the ink becomes bubbles and remains in the ink, it may cause problems such as non-ejection of ink from the nozzle It becomes.
For this reason, in the conventional ink jet recording apparatus, a degassing device is provided in the ink path for supplying ink from the ink tank to the ink jet head, and the dissolved gas in the ink is removed (for example, Patent Document 1).

The deaeration device includes a vacuum module having a sealed region that allows ink supplied to the inkjet head to pass therethrough and separated from the ink by a hollow fiber membrane, and a vacuum pump that evacuates the sealed region of the vacuum module. Have. A diaphragm pump is used as the vacuum pump.
In the ink jet recording apparatus, when ink is supplied at the time of image formation, a vacuum pump is driven to vacuum the ink passing through the deaeration device through the hollow fiber membrane. Thereby, bubbles in the ink were sucked out to the sealed region side through the hollow fiber membrane, and good discharge was performed.

JP-A-11-42771

However, in the conventional inkjet recording apparatus described in Patent Document 1, it is necessary to increase the degree of vacuum for vacuuming depending on the type of ink. In such a case, moisture in the ink is also sucked out through the hollow fiber membrane. was there.
And when the vacuum pump consisting of a diaphragm pump sucks this moisture-containing gas, it adheres to the internal valve and deteriorates the movement of the valve, thereby causing a decrease in suction force or operation while remaining attached to the diaphragm It has been a problem to shorten the life of the apparatus by deteriorating the diaphragm by drying after stopping.

  An object of the present invention is to reduce the influence of ink moisture.

  In order to solve the above problems, the present invention relating to an ink jet recording apparatus includes a deaeration module provided in the middle of an ink supply path for supplying ink from an ink tank to an ink jet head, and a gas permeable membrane of the deaeration module. A vacuum pump that depressurizes the ink, an air release valve that can switch between an airtight state and an air release state in a path connecting the deaeration module and the vacuum pump, the vacuum pump, and the air release valve And a control device that controls the drying of the pump by operating the vacuum pump with the atmosphere release valve in the atmosphere release state.

  In order to solve the above problems, the present invention according to a method for controlling an ink jet recording apparatus includes a deaeration module provided in the middle of an ink supply path for supplying ink from the ink tank to the ink jet head, and the degassing module. A vacuum pump for depressurizing the ink via a gas permeable membrane of a gas module, and provided between the degas module and the vacuum pump, wherein the vacuum pump is connected to the degas module and is opened to the atmosphere. And a control device for controlling the vacuum pump and the air release valve, wherein the control device sets the air release valve to an air release state. Pump drying control for operating the vacuum pump is performed.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus may be configured such that the ink jet recording apparatus includes a liquid feed pump for supplying ink to the ink jet head side through a deaeration module.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus may be configured such that the pump drying control is performed while the liquid feed pump is stopped.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus may be configured such that the control apparatus executes the pump drying control at the time of maintenance of the ink jet head or immediately after the end of the maintenance. good.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus include that the control device is configured to supply liquid continuously for a predetermined time or more. The pump drying control may be performed.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus are as follows: the control apparatus starts driving at the upper limit pressure and stops driving at the lower limit pressure with respect to the vacuum pump. The pressure maintaining control is performed, and the control device determines that [the degassing ink consumption time determined by the ink capacity of the degassing module and the ink consumption speed at the time of image formation]> ([specified drying time in the pump drying control] + [Depressurization maintaining time for maintaining the pressure below the upper limit pressure in order to degas the ink in the deaeration module] + [First pump continuous required for lowering the suction pressure from the atmospheric pressure to the lower limit pressure by the vacuum pump] It is good also as a structure which performs pump drying control after reaching | attaining the said lower limit pressure by the said pressure maintenance control when it becomes drive time]).

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus are as follows: the control apparatus starts driving at the upper limit pressure and stops driving at the lower limit pressure with respect to the vacuum pump. When the second continuous pump driving time required for lowering the suction pressure from the upper limit pressure to the lower limit pressure by the vacuum pump exceeds a predetermined determination time, the ink jet recording apparatus performs pressure maintenance control. It is good also as a structure which performs pump drying control at the time of the fall which cut | disconnects the main power supply.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus may be configured such that the control apparatus performs a wiping process of the ink jet head in accordance with the pump drying control at the time of falling. .

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus are such that the control device exceeds the second determination time that is longer than the determination time. The vacuum pump may be informed of an abnormality.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus are characterized in that the control device sets a lower limit that is targeted within a predetermined time by the vacuum pump after the pump drying control. It is good also as a structure which alert | reports abnormality of the said vacuum pump when it cannot be pressure-reduced to a pressure.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus include the deaeration module, the vacuum pump, and the air release valve individually corresponding to a plurality of colors of ink. The control device may be configured to identify one or more colors that are not used from image data for image formation, and to perform pump drying control on the vacuum pump corresponding to the ink of the specified color at the time of image formation. good.

  Further, the present invention relating to the ink jet recording apparatus and the present invention relating to the control method of the ink jet recording apparatus include the deaeration module, the vacuum pump, and the air release valve individually corresponding to a plurality of colors of ink. The control device specifies one or more colors having the highest ink usage from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the specified color ink after image formation It is good also as a structure which performs.

  Further, the present invention according to the ink jet recording apparatus and the present invention according to the control method of the ink jet recording apparatus include the deaeration module, the vacuum pump, and the air release valve individually corresponding to a plurality of ink jet heads, The control device may be configured to identify one or more ink jet heads that are not used from image data for image formation, and to perform pump drying control on the vacuum pump corresponding to the identified ink jet head during image formation. .

In order to solve the above-described problems, the present invention performs pump drying control in which the control device operates the vacuum pump with the atmosphere release valve in the atmosphere release state, and thus introduces the outside air that is drier than the deaeration module into the pump. And moisture in the pump can be eliminated.
As a result, the ink can be deaerated favorably by the vacuum pump, and it is possible to extend the life by suppressing the deterioration of the vacuum pump.

It is a perspective view of an inkjet recording device. It is a top view which shows arrangement | positioning of the head on a carriage. It is a schematic diagram which shows the outline of an ink supply apparatus. It is a block diagram which shows the outline of a deaeration apparatus. It is a diagram which shows the relationship between the pressure in a path | route at the time of on-off control of the vacuum pump of a deaeration apparatus, and elapsed time. It is a block diagram which shows the control system of an inkjet recording device. It is a flowchart which shows pump drying control. It is a flowchart which shows the process which performs pump drying control at the time of power activation. It is a flowchart which shows the process which performs pump drying control at the time of standby. It is a flowchart which shows the process which performs pump drying control at the time of image formation. It is a flowchart which shows the process which performs pump drying control at the time of the extrusion process of a maintenance. It is a flowchart which shows the process which performs pump drying control at the time of the wipe process of a maintenance. It is a flowchart which shows the process which performs pump drying control at the time of a nozzle missing confirmation process. It is a flowchart which shows the process which performs pump drying control at the time of a power supply fall. It is explanatory drawing which shows the result of the effect test by execution of pump drying control with respect to a vacuum pump. It is explanatory drawing which shows the result of the confirmation test of the influence of the water | moisture content (water vapor | steam) with respect to a vacuum pump. It is explanatory drawing which shows the result of the confirmation test of the influence of the water | moisture content (water vapor | steam) removal with respect to a vacuum pump.

  An ink jet recording apparatus 1 equipped with an ink supply apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing the entire inkjet recording apparatus 1.

The ink jet recording apparatus 1 is a carriage on which a transport device 20 that transports a recording medium along a horizontal direction and a plurality of heads 3 (see FIG. 2) as ink jet heads that eject ink from above onto the transported recording medium. 4, a main scanning device 5 that transports the carriage 4 along a horizontal direction orthogonal to the transport direction of the recording medium, a maintenance unit 7 that performs maintenance of each head 3 mounted on the carriage 4, and a carriage 4. In addition, a nozzle moisturizing unit 6 that moisturizes the nozzles of each head 3, an ink supply device 8 (see FIG. 3) that supplies ink to each head 3 mounted on the carriage 4, and a control unit that controls these components As a control device 9 (see FIG. 6) and a frame 100 that supports the whole.
In the following description, the horizontal direction and the direction along the conveyance direction of the recording medium are the Y-axis direction, the horizontal direction and the direction along the conveyance direction of the carriage 4 are the X-axis direction or the main scanning direction, and the vertical direction. The vertical direction is referred to as the Z-axis direction.

[Conveyor]
The transport device 20 includes a drive roller 21 and a driven roller (not shown), a drive motor 22, and a transport belt 23.
The driving roller 21 and the driven roller are rotatably supported, and the driving roller 21 is disposed so as to extend in the main scanning direction X. The drive motor 22 is a drive source for rotationally driving the drive roller 21, and is attached to one end side of the drive roller 21.
The conveyor belt 23 is formed in an endless shape, and is stretched between the driving roller 21 and the driven roller. When the driving roller 21 rotates, the conveying belt 23 circulates between the driving roller 21 and the driven roller and conveys the recording medium placed on the upper surface thereof in the conveying direction F along the Y-axis direction. When the rotation of the roller 21 is stopped, the circulation between both rollers is stopped, and the conveyance of the recording medium is stopped.
When the head 3 completes one-way scanning along the X-axis direction according to the control of the control device 9, the drive motor 22 rotates the drive roller 21 by a predetermined amount to convey the recording medium by a predetermined distance in the conveyance direction. When the head 3 starts scanning in the direction opposite to the main scanning direction X and finishes, the drive roller 21 is rotated again by a predetermined amount, and the recording medium is transported by a predetermined distance in the transport direction F and stopped. The recording medium is so-called intermittently conveyed.

As the recording medium, it is possible to use resin films, metals, etc. in addition to paper and fabric.
Moreover, the conveying apparatus 20 is not restricted to said intermittent conveyance. For example, for each color on the carriage 4, a head group including nozzle rows along the X-axis direction is provided for almost the entire width of the transport belt 23 in the X-axis direction, and the head groups of the respective colors are sequentially arranged in the Y-axis direction. The image forming may be performed while the recording medium is conveyed in the Y-axis direction by the conveying device 20 in a state where the carriage 4 is mounted in a line and stopped at a position directly above the conveying belt 23.

[flame]
As shown in FIG. 1, the frame 100 includes a rectangular main body portion 101 extending along the X-axis direction, a first base portion 102 that supports one end portion in the X-axis direction of the main body portion 101, and the main body portion 101. And the second base portion 103 that supports the other end portion in the X-axis direction.
The first base portion 102 supports the one end portion of the main body portion 101 from below while storing and holding the nozzle moisturizing portion 6 therein. Further, the second base portion 103 supports the other end portion of the main body portion 101 from below while storing and holding the maintenance portion 7 therein.
The main body 101 stores and holds a pair of carriage rails 51, 51 of the main scanning device 5, which will be described later, in the X-axis direction, and the carriage 4 extends in the X-axis direction inside the main body 101. Are transported.
The first base portion 102 and the second base portion 103 are disposed on both sides in the X-axis direction with the above-described transport device 20 interposed therebetween, and the main body portion 101 is installed above the transport device 20. Thus, it is possible to perform image formation by ejecting ink from each head 3 mounted on the carriage 4 while transporting the carriage 4 in a direction orthogonal to the transport direction of the recording medium by the transport device 20.

[Main scanning device and carriage]
The main scanning device 5 includes a pair of bar-shaped carriage rails 51 and 51 supported so as to extend along the X-axis direction inside the main body 101 of the frame 100. The pair of carriage rails 51 and 51 are provided so as to straddle the upper portion of the conveying belt 23 of the conveying device 20. A box-shaped carriage 4 is supported on the carriage rails 51 and 51 so as to be reciprocally movable along the X-axis direction.

The carriage 4 is a substantially rectangular casing with an open top, and a plurality of heads 3 are mounted on the bottom plate. As shown in FIG. 1, the carriage 4 has arm portions 42 and 42 extending toward both sides in the Y-axis direction at the upper part of both side surfaces in the Y-axis direction, and the arm portions 42 and 42 are respectively linear guides. The carriage rails 51 and 51 are placed on the carriage rails 51 and 51 so that the carriage rails 51 and 51 can slide along the X-axis direction.
A linear motor is provided between the carriage rails 51 and 51 and the arm portions 42 and 42 of the carriage 4. That is, each carriage rail 51, 51 is equipped with a stator of a linear motor, each arm 42, 42 of the carriage 4 is equipped with a mover, and the carriage 4 is controlled by current control of the stator side coil. A transport operation along the X-axis direction is given.

FIG. 2 is a schematic explanatory view of the bottom plate 41 of the carriage 4 as viewed from above. In this inkjet recording apparatus 1, Y (yellow), Lm (light magenta), Or (orange), M (magenta), Bk (black), Bl (blue), Lk (light black), C (cyan), Lc Each of the nine colors (light cyan) includes nine heads 3, and a total of 81 heads 3 are attached to the bottom plate of the carriage 4.
As shown in the figure, the head groups of each color are arranged in the order of Y, Lm, Or, M, Bk, Bl, Lk, C, and Lc along the X-axis direction, and the nine heads 3 of each head group are arranged. Are arranged in a staggered manner along the Y-axis direction.
The bottom plate 41 is provided with a slit-shaped opening along the Y-axis direction for each mounting position of each head 3, and each head 3 attached to the bottom plate 41 from above is directly below the carriage 4 through the opening. Ink droplets can be ejected.
As described above, the nine heads 3 are arranged in a staggered manner for each color, so that the ink of each color can be placed at an arbitrary position within the range of almost the entire width in the Y-axis direction on the bottom plate 41 of the carriage 4. It is possible to perform discharge.

[head]
FIG. 3 is a sectional view showing a schematic structure of the head 3. The head 3 has a plurality of nozzle rows along the Y-axis direction arranged in the X-axis direction on the nozzle plate facing the recording medium conveyed at the bottom. The head 3 includes an ink flow path for guiding ink to each nozzle and a plurality of piezoelectric elements provided for each nozzle. The ink flow path communicates with a first port 341 and a second port 342 provided in the upper part of the head 3, and ink is supplied from the first port 341 to each nozzle, and the second port Excess ink is discharged from 342.

[Maintenance Department]
The maintenance unit 7 performs maintenance of each head 3 during the non-recording operation. The maintenance unit 7 is provided on one end side of the carriage rails 51 and 51, separated from the transport device 20. That is, maintenance is performed in a state where the carriage 4 has moved to a position where the carriage rails 51 and 51 are opposed to the maintenance unit 7 at one end thereof.
The maintenance unit 7 includes a wiping device that wipes residual ink and dirt on the lower surface of the nozzle plate of each head 3 (wiping process), an ink tray 71 that serves as a tray when ink is ejected by the head 3, and ( 3), and a nozzle sensor 72 (see FIG. 6) for detecting the nozzle in which the nozzle is missing.

  The wiping device mainly includes a cleaning roller that is slidably contacted with the lower surface of the nozzle plate 31 and is rotatable about a rotation axis along the X-axis direction, and a roller conveyance mechanism that conveys the cleaning roller along the Y-axis direction. The configured cleaning roller has a width in the X-axis direction so as to enable wiping of the three color head groups out of the nine color head groups mounted on the carriage 4. All the heads 3 are cleaned by a reciprocating half moving operation. This prevents nozzle clogging due to solidification of residual ink.

Further, ink is discharged to the ink tray 71 during maintenance by an extrusion process performed with the ink supply pressure of the ink supply device 8 and a flushing process discharged by driving the piezoelectric element.
The extrusion process eliminates clogging of the ink flow path in the head 3 by discharging a larger amount of ink than usual from the nozzles of each head 3.
The flushing process is a small number of ejections performed after the wipe process or periodically, and is a process for preventing clogging due to ink drying.

  Also, ink is ejected to the ink tray 71 during the nozzle missing detection process. Nozzle deficiency is a process of detecting nozzles that have failed to eject against the ink ejection command. In this process, ink is ejected a plurality of times based on the ejection command to some or all of the nozzles of each head 3, and the droplets ejected by the nozzle sensor 72 provided in the ink tray 71 at that time are detected. I do. The nozzle sensor 72 is, for example, a line-type light receiving sensor along the Y-axis direction, and is disposed so that the discharged liquid droplets traverse the light receiving surface of the nozzle sensor 72. When a droplet is ejected from the nozzle, a change in the amount of light received occurs in each part of the light receiving surface of the nozzle sensor 72 due to the passage of the droplet, thereby determining whether the droplet is ejected or not ejected. It is possible.

[Nozzle moisturizer]
The nozzle moisturizing unit 6 is provided on the other end side of the carriage rails 51, 51, separated from the transport device 20. That is, during the non-recording operation, the carriage 4 moves to a position facing the nozzle moisturizing unit 6 at the other end of the carriage rails 51 and 51, and in this state, the nozzles of the heads 3 are moisturized.
In other words, the nozzle moisturizing unit 6 is in close contact with each nozzle of the nozzle plate 31 so that the inside of each nozzle is connected to the moisturizing liquid storage unit. It is comprised with the raising / lowering mechanism.

[Ink supply device]
FIG. 3 is an explanatory diagram showing a schematic configuration of the ink supply device 8. The ink jet recording apparatus 1 includes the ink supply device 8 for each color.
The ink supply device 8 includes main tanks 81 and 81 as two ink tanks for storing ink, a sub tank 82 as an ink tank to which ink is supplied from each main tank 81 and 81, and a downstream of the sub tank 82 in the ink supply direction. A deaeration device 83 provided on the side, an intermediate tank 84 provided on the downstream side of the deaeration device 83 in the ink supply direction and temporarily storing ink, and a downstream side of the intermediate tank 84 in the ink supply direction And a common flow path 87 in which the first ports 341 of the heads 3 are connected in parallel to supply ink to the heads 3.
In FIG. 3, the ink tray 71 of the maintenance unit 7 is also illustrated.

The main tanks 81 and 81 are containers whose upper portions are open to the atmosphere, and the two main tanks 81 and 81 are both detachable from the ink jet recording apparatus 1 so that they can be replaced when empty. ing. In addition, since there are two main tanks 81 and 81, ink can be supplied from the other main tank 81 even when one of the tanks is empty and when it is replaced, the recording operation of the inkjet recording apparatus 1 is possible. It is possible to avoid interruptions. The number of mounted solids in the main tank 81 may be increased.
Reference numeral 815 in FIG. 3 is a remaining amount sensor for detecting whether or not the ink in each of the main tanks 81 and 81 is empty.

Between the main tanks 81 and 81 and the sub tank 82, one end portion branches to the main tank 81 and 81 side, and the other end portion joins to the first ink flow path 811 reaching the sub tank 82. Is provided. In the vicinity of the main tanks 81 and 81 in the first ink flow path 811, tank valves 812 and 812 are provided as connection switching units that are electromagnetic valves that can switch the open / close state of the flow paths.
Further, a filter 813 for removing contaminants such as dust and dust from the ink is provided in the middle of the path on the sub tank 82 side in the first ink flow path 811, and further on the sub tank 82 side than the filter 813. A first liquid feed pump 814 is provided as a first liquid feed section that sends ink to the sub tank side.

The sub tank 82 has a funnel shape having a side wall portion 821 whose diameter decreases toward the lower side, and the upper portion is closed by a top plate 822.
The sub-tank 82 is connected to the second ink flow path 823 at the center of the bottom, so that the ink in the sub-tank 82 can be supplied to the deaerator 83 through the second ink flow path 823.
In addition, an air release pipe 824 for maintaining the inside of the sub tank 82 at atmospheric pressure is attached to the top plate 822 of the sub tank 82. The air release pipe 824 is equipped with a filter 825 for preventing intrusion of dust and dirt from the outside.

In addition, the top end of the first ink flow path 811 is connected to the top plate 822 of the sub tank 82 in a state of penetrating the top plate 822 and entering the inside.
The front end portion of the first ink flow path 811 extends to a position in contact with or just before the inner surface of the side wall 821 of the sub tank 82, and the ink supplied from the first ink flow path 811 passes through the side wall 821. Then, the liquid is poured into the liquid level in the sub tank 82.
The sub tank 82 has an upper limit position of the ink liquid level determined by liquid level monitoring control described later, and the tip of the first ink flow path 811 is positioned higher than the upper limit position of the ink liquid level. Ink is supplied to the side wall 821.

Further, in the sub tank 82, a first liquid level sensor 826 that defines the upper limit position of the ink liquid level in the liquid level monitoring control described later, and a second liquid level sensor 827 that defines the lower limit position of the ink liquid level. And are provided.
Each of these liquid level sensors 826 and 827 is a float type sensor provided with a float, and it is possible to detect whether the liquid level is above or below the upper limit position or the lower limit position from the height of the float. . The liquid level monitoring control will be described in detail later.

  Between the sub tank 82 and the deaerator 83, the above-described second ink flow path 823 is provided. In the middle of the second ink flow path 823, a check valve 828 for preventing the ink from returning from the deaeration device 83 to the sub tank 82, and a second liquid feed for sending ink from the sub tank 82 to the deaeration device 83. A second liquid feed pump 829 as a unit is provided.

  FIG. 4 is a configuration diagram of the deaeration device 83. As illustrated, the deaeration device 83 includes a deaeration module 831 configured by a gas permeable membrane, a vacuum pump 832 for depressurizing the inside of the deaeration module 831, and the vacuum pump 832 and the deaeration. A vacuum path 836 connecting the module 831, a pressure switch 833 as a pressure detection unit provided in a branch path 837 branched from the vacuum path 836, and ON / OFF operation according to the pressure in the vacuum path 836; A trap 838 for capturing the liquid in the vacuum path 836 and an air release valve 834 capable of switching the inside of the vacuum path 836 between an airtight state and an air release state are provided.

  A large number of hollow fiber membranes 831a are bundled and accommodated in the deaeration module 831, and the inside thereof is partitioned into two spaces inside and outside each hollow fiber membrane 831a. Outside the deaeration module 831, an ink inlet 831 b connected to the second ink flow path 823 and an ink outlet 831 c connected to the third ink flow path 835 toward the inkjet head 3 side are provided. The ink inlet 831b and the ink outlet 831c communicate with the outer space of each hollow fiber membrane 831a in the deaeration module 831. The ink sent from the sub tank 82 by the second liquid feed pump 829 is the ink inlet. The air flows into the deaeration module 831 from 831b, passes through the gaps of a bundle of many hollow fiber membranes 831a, and flows out from the ink outlet 831c.

  On the other hand, the vacuum path 836 communicates with the inner space of each hollow fiber membrane 831a in the deaeration module 831. By driving the vacuum pump 832, the inner space of each hollow fiber membrane 831a is connected via the vacuum path 836. Is reduced to a predetermined pressure. By this decompression, dissolved oxygen is degassed and removed from the ink in the outer space in contact with the outer surface of each hollow fiber membrane 831a through the hollow fiber membrane 831a.

  As the deaeration module 831, one side of a gas permeable membrane is brought into contact with ink, and the other side is decompressed by a vacuum pump 832 via a vacuum path 836 so that dissolved oxygen in the ink can be removed. However, it is preferable to use a deaeration module in which a number of hollow fiber membranes are bundled as a membrane.

The vacuum pump 832 is a diaphragm pump including a pump chamber having a diaphragm that can be expanded and contracted, and a drive source that operates the diaphragm so that the volume of the pump chamber expands and contracts. The pump chamber includes a suction port provided with a check valve that allows only inflow of fluid from the outside, and a discharge port provided with a check valve that allows only discharge of particles from the inside. Yes.
In this diaphragm pump, adhesion of moisture to the diaphragm and the check valve causes deterioration, deterioration, and failure of the pump performance.

  The trap 838 is used to prevent ink or moisture from entering the vacuum path 836 from the side of the degassing module 831 and prevent them from reaching the vacuum pump 832. Moisture can be stored inside. As a result, the vacuum pump 832 suppresses breakage, malfunction, and deterioration due to ink and moisture. However, since the trap 838 has a structure that captures water droplets by dropping, it cannot capture moisture that has once vaporized and reaches the vacuum pump 832.

  The pressure switch 833 is a pressure detection means, and has a cylinder-shaped pressure chamber 833a having an enlarged diameter at the tip of the branch path 837, and a piston-like movable element 833b slidable in the pressure chamber 833a. Yes. The outer peripheral surface of the mover 833b is fitted in an airtight manner with the inner peripheral surface of the pressure chamber 833a, and one end is attached with a predetermined force in a direction away from the deaeration module 831 by a tension spring 833c fixed to the frame inside the machine. It is energized.

  The movable element 833b is provided with a switch operation portion 833d extending outside the pressure chamber 833a. When the vacuum pump 832 is driven to reduce the pressure in the vacuum path 836 to a predetermined lower limit pressure, the branch path 837 is provided. The pressure chamber 833a is also depressurized via the, and when the mover 833b moves to the deaeration module 831 side against the tension spring 833c by a predetermined distance, for example, it contacts the switch part 833e attached to the frame inside the machine, A signal ON is transmitted to the control device 9. Further, when the inside of the vacuum path 836 rises to an upper limit pressure higher than the lower limit pressure, the mover 833b is pulled in a direction away from the deaeration module 831 by the action of the tension spring 833c, and the switch operation unit 833d and the switch unit 833e are separated. As a result, the electrical signal to the control device 9 is turned off.

  Therefore, the pressure switch 833 is turned on when detecting that the inside of the vacuum path 836 has reached a predetermined lower limit pressure by driving the vacuum pump 832, and permeates each hollow fiber membrane 831 a by stopping the vacuum pump 832. It operates so as to be turned off when it is detected that the pressure has risen above the predetermined lower limit pressure and reached the upper limit pressure due to the increase in the gas concentration.

FIG. 5 shows that the pressure switch 833 is used by the control device 9 to maintain the inner space of each hollow fiber membrane 831a in the deaeration module 831 between the upper limit pressure and the lower limit pressure described above. 6 is a graph showing the relationship between the pressure value in the vacuum path 836 and the elapsed time when pressure maintenance control is performed on the pressure. Note that the pressure maintenance control described here is a control example when pump drying control described later is not taken into consideration.
A symbol t4 in FIG. 5 indicates a time required to reduce the suction pressure from the atmospheric pressure to the lower limit pressure by driving the vacuum pump 832 (referred to as a first pump continuous driving time t4).
5 indicates the time required to reduce the suction pressure from the upper limit pressure to the lower limit pressure by driving the vacuum pump 832 (second pump continuous drive time t8).
5 indicates the time required for the pressure to increase from the lower limit pressure to the upper limit pressure due to deaeration when the vacuum pump 832 is stopped.

  When the dissolved oxygen in the ink is removed by the deaeration module 831, as shown in the figure, when the vacuum pump 832 is driven and the pressure in the vacuum path 836 is reduced to the lower limit pressure, the pressure switch 833 is turned ON to turn the vacuum An operation for stopping the driving of the pump 832 is performed, and deaeration is performed during the stop. Under this pressure maintenance control, when the vacuum pump 832 is driven, the inside of the vacuum path 836 is gradually reduced, and when the pressure is reduced to a lower limit pressure (for example, about −70 kPa), the switch of the pressure switch 833 The operation unit 833d and the switch unit 833e come into contact with each other to transmit an electric signal ON to the control device 9, and the vacuum pump 832 is set to stop driving by the CPU 91 (see FIG. 6) of the control device 9.

  The values of the lower limit pressure in the vacuum path 836 where the pressure switch 833 is turned on and the upper limit pressure where the pressure switch 833 is turned off can be changed by adjusting the spring pressure, adjusting the stroke of the switch unit 833e, and the like. It can be set appropriately depending on the amount of dissolved oxygen in the ink.

  After the pressure in the vacuum path 836 is reduced to the lower limit pressure and the vacuum pump 832 stops driving, oxygen gradually passes through the hollow path 836 through the hollow fiber membrane 831a. The pressure increases gradually. Here, when the pressure in the vacuum path 836 exceeds the upper limit pressure, the switch operation unit 833d and the switch unit 833e of the pressure switch 833 are set apart so that the electrical signal is OFF, and the CPU 91 of the control device 9 The operation of depressurizing the vacuum pump 832 is repeated so that the pressure value in the vacuum path 836 becomes the lower limit pressure again by turning off the electric signal.

  The atmosphere release valve 834 is an electromagnetic valve capable of switching the vacuum path 836 between an airtight state and an atmosphere release state according to an operation command from the outside, and performs the switching according to the operation control of the control device 9.

A third ink flow path 835 is provided between the deaeration module 831 and the intermediate tank 84. Ink is supplied to the intermediate tank 84 by the supply pressure of the second liquid feed pump 829 via the second and third ink flow paths 823 and 835.
The intermediate tank 84 is formed in a flexible bag shape, and expands / contracts as the amount of stored ink fluctuates.
The intermediate tank 84 is also provided with a liquid amount sensor 841 for detecting a state where a specified amount of ink is stored. When ink is supplied from the sub tank 82, ink is supplied by the second liquid feed pump 829 until the liquid amount sensor 841 detects that the specified amount has been reached.

  Between the intermediate tank 84 and the negative pressure forming portion 86, fourth to seventh ink flow paths 842 to 845 are provided, and ink is supplied through these. A first three-way switching valve 846, which is an electromagnetic switching valve, is interposed between the fourth ink channel 842 and the fifth ink channel 843, and the fifth ink channel 843 and the sixth ink channel. A second three-way switching valve 847 that is an electromagnetic switching valve is interposed between the flow path 844 and a sixth switching path that is an electromagnetic switching valve is provided between the sixth ink flow path 844 and the seventh ink flow path 845. Three three-way switching valves 848 are interposed.

  Further, a check valve 849 that allows only the flow in the direction from the first three-way switching valve 846 to the second three-way switching valve 847 and the check valve 849 allow the fifth ink flow path 843. When a predetermined pressure is exceeded on the downstream side of the third liquid feeding pump 850 serving as a liquid feeding unit that feeds the liquid in the same direction as the direction, the ink is returned to the sub tank 82. A relief valve 851 is provided.

  In the middle of the sixth ink channel 844, one end of the branch channel 852 is joined and connected, and the other end of the branch channel 852 is connected to the first three-way switching valve 846. The first three-way switching valve 846 is controlled by the control device 9 so that the fifth ink channel 843 is connected to the fourth ink channel 842 and the fifth ink channel 843 is branched. It is possible to switch to the state connected to 852.

  The second three-way switching valve 847 is also connected to a return flow path 853 for returning ink to the sub tank 82, and the second three-way switching valve 847 is controlled by the control device 9 in accordance with the fifth It is possible to switch between a state in which the ink channel 843 is connected to the sixth ink channel 844 and a state in which the fifth ink channel 843 is connected to the return channel 853.

The first and second three-way switching valves 846 and 847 are combined and controlled by the control device 9 to be simultaneously switched, and the fourth, fifth and sixth ink flow paths 842, 843 and 844 are passed from the intermediate tank 84. After that, a supply connection state (white arrow in FIG. 3) in which ink is fed to the negative pressure forming unit 86 side (or head side), and the branch flow path 852 and the fifth from the negative pressure forming unit 86 side (or head side). Control is performed to switch between the return connection state (black arrow in FIG. 3) in which ink is fed to the sub tank 82 side through the ink flow path 843 and the return flow path 853.
That is, using the delivery pressure of the third liquid feed pump 850, the supply of ink to the negative pressure forming unit 86 side and the recovery of ink from the negative pressure forming unit 86 side can be selectively performed. Is possible.

The third three-way switching valve 848 is also connected to a bypass flow path 854 that supplies ink to the head side without passing through the negative pressure forming portion 86, and the sixth ink flow path 844 is controlled by the control device 9. It is possible to switch between a state in which the seventh ink channel 845 is connected and a state in which the sixth ink channel 844 and the bypass channel 854 are connected.
That is, by this switching, a state where ink can be supplied and recovered to the negative pressure forming unit 86 and a state where ink can be supplied and recovered to the head 3 side (strictly, the common flow path 87). It is possible to switch between.

The negative pressure forming portion 86 includes a rectangular main body container 861 having a large opening on the front surface, a film member 862 made of a flexible resin film that closes the opening of the main body container 861, and the inside of the main body container 861 from the inside to the outside. It is mainly composed of a spring (not shown) that presses the center of the film member 862 toward the center.
The main body container 861 is connected to the aforementioned seventh ink flow path 845 and the eighth ink flow path 863 leading to the common flow path 87 to which all the first ports 341 of the nine heads 3 are connected in parallel. Yes.
Further, since the film member 862 is pressed outward by the center by a spring, the film member 862 is in a tension state with a shape that protrudes outward in a substantially conical shape.

Then, after the ink is filled in the main body container 861 at the same pressure as the atmospheric pressure, the first and second three-way switching valves 846 and 847 are returned to the connected state and the ink is collected from the main body container 861. The inside of each head 3 can be brought into a negative pressure state lower than the atmospheric pressure via the path 87. In this way, the inside of the head 3 is maintained at a negative pressure because, for example, if the inside of the nozzle 3 is at atmospheric pressure, ink is likely to leak from the nozzle, and ink tends to adhere to the periphery of the nozzle, resulting in poor ejection. This is because the variation in the dot diameter tends to occur.
Note that the target pressure, which is a negative pressure, can be controlled by adjusting the amount of ink collected in the main body container 861.

  A communication pipe 864 that communicates with the inside of the main body container 861 and extends upward is provided on the upper part of the main body container 861 of the negative pressure forming portion 86. A liquid level sensor 865 is attached to the end of the communication pipe 864 on the main body container 861 side, and a pressure sensor 866 is attached to the upper end of the communication pipe 864. Further, a horizontally extending branch pipe 867 having one end opened to the atmosphere is connected to an intermediate portion of the communication pipe 864. An air filter 869 for filtering is provided.

  These are structures used when supplying ink into the main body container 861 and controlling it to a predetermined negative pressure. That is, ink is supplied into the main body container 861 until the liquid level is detected by the liquid level sensor 865 with the open valve 868 opened, and then the open valve 868 is closed, and the pressure sensor 866 sets the target negative pressure. Ink is collected from the main body container 861 until the pressure is indicated. Thereby, the inside of each head 3 can be brought into a predetermined negative pressure state through the negative pressure forming portion 86.

  The eighth ink channel 863 extending from the negative pressure forming unit 86 joins the detour channel 854 described above and is connected to the common channel 87 on the way. In addition, a protective valve 871 that is a normally open electromagnetic valve is provided on the negative pressure forming part 86 side of the eighth ink flow path 863 from the junction with the bypass flow path 854.

The common flow path 87 is mounted on the carriage 4, the eighth ink flow path 863 is connected to the upper part thereof, and the first ports 341 of the nine heads 3 for the same color are arranged in parallel at the bottom part. It is connected to the.
Further, a waste liquid flow path 872 serving as a discharge flow path leading to a waste liquid tank (not shown) is connected to the upper part of the common flow path 87. The waste liquid flow path 872 is provided with a waste liquid valve 873 which is a normally closed electromagnetic valve. When the common flow path 87 is filled with ink, the waste liquid valve 873 is opened to discharge bubbles.

The common flow path 87 is connected to the first port 341 of each head 3 via a recording operation valve 874 which is a normally open electromagnetic valve. The second ports 342 of each head 3 are connected in parallel to the common waste liquid flow path 876 via a normally closed maintenance valve 875, respectively.
Each head 3 is supplied with ink from the common flow path 87 via the first port 341 during image formation or maintenance. At the time of image formation, the maintenance valve 875 of the second port 342 is closed, and when performing maintenance processing (such as discharging bubbles) that does not discharge ink, the maintenance valve 875 is opened and the first port 341 is opened. Ink is supplied so that ink flows in and is discharged from the second port 342.

[Control device]
FIG. 6 is a block diagram showing a control system of the ink supply device 8. The control device 9 shown in FIG. 6 controls the entire ink jet recording apparatus 1. Here, only the configuration of the ink supply device 8 is illustrated, and the other configurations are not shown. Further, only one of the plurality of configurations is illustrated.
The control device 9 not only controls the ink supply device 8 such as converting image data of an image to be recorded on a recording medium input from an external device into data corresponding to each nozzle of the head 3, but also the ink jet recording device 1. It also controls the drive of each part.
As shown in FIG. 6, the control device 9 is composed of a general-purpose computer in which a CPU 91, a ROM 92, a RAM 93, an input / output interface (not shown) and the like are connected to a bus.
The control device 9 includes first to third liquid feed pumps 814, 829, 850, a vacuum pump 832, a tank valve 812, an atmosphere release valve 834, and first to third three-way switching valves 848, 847, 848, An open valve 868, a protective valve 871, a waste liquid valve 873, a recording operation valve 874, and a maintenance valve 875 are connected, and the control device 9 controls them.
Further, the remaining amount sensor 815, first and second liquid level sensors 826, 827, liquid level sensor 841, liquid level sensor 865, pressure switch 833, pressure sensor 866, and nozzle sensor 72 are connected to the control device 9. From these, various detection signals are inputted.
In addition, a power switch 96 is connected to the control device 9, and the control device 9 receives a power-on signal input and performs a main power-up process, and receives a power-off signal input and receives a power-off signal input. Execute the lowering process.
Further, an input operation unit 94 that performs support input such as execution of various operations from the operator, a display unit 95 that displays various information such as error information, and the like are also connected to the control device 9.
And the control apparatus 9 implements various control etc. with respect to each said control object according to these detection information, but in this embodiment, focusing on the structure of the periphery of the deaeration apparatus 83 especially. The control related to the deaeration process for removing the dissolved oxygen from the ink will be mainly described.

[Pump drying control]
As described above, the vacuum pump 832 of the degassing device 83 has an adverse effect on the adhesion of internal moisture due to its structure. Therefore, the atmosphere is introduced into the vacuum pump 832 at various timings to be described later to remove the moisture. To perform pump drying control.
This pump drying control will be described with reference to the flowchart of FIG.

  In this pump drying control, the CPU 91 opens the atmosphere release valve 834 (step S1), starts driving the vacuum pump 832 (step S3), and introduces the atmosphere into the vacuum pump 832. Thereby, even when the moisture that has entered from the deaeration module 831 reaches the vacuum pump 832, the moisture is removed by the atmosphere with lower humidity, and the inside of the vacuum pump 832 is promoted to dry.

Then, the air introduction is continued for a predetermined drying time t2 (step S5). The drying time t2 can be appropriately changed by an input from the input operation unit 94.
When the drying time t2 has elapsed, the CPU 91 closes the atmosphere release valve 834 (step S7), and the vacuum pump 832 depressurizes the inside of the vacuum path 836 that has been at atmospheric pressure. At this time, the CPU 91 starts measuring the first pump continuous drive time t4 required for reducing the suction pressure from the atmospheric pressure to the lower limit pressure by the vacuum pump 832 in order to determine whether the vacuum pump 832 is abnormal. To do.

Next, the CPU 91 determines the input of the electrical signal ON of the pressure switch 833 (step S9). If there is no input, the current first pump continuous drive time t4 determines whether the vacuum pump 832 is abnormal. It is determined whether or not the first determination time t3 is exceeded (step S11). If the first pump continuous drive time t4 does not exceed the first determination time t3, the process returns to the determination in step S9.
Further, when t4> t3, control is performed to notify the abnormality of the vacuum pump 832 on the assumption that the suction capacity of the vacuum pump 832 is greatly reduced. As the notification control, for example, an abnormality notification screen is displayed on the display unit 95 provided in the control device 9, a lamp is turned on, a buzzer is sounded, and the like. In this case, the pump drying control is suspended until the vacuum pump 832 is restored.

If the electrical signal ON of the pressure switch 833 is detected in step S9, the vacuum pump 832 is stopped (step S13) and the pump drying control is performed assuming that the vacuum path 836 has reached the lower limit pressure. finish.
Further, the CPU 92 determines and records the measured value of the first pump continuous driving time t4 until the time when the electrical signal ON of the pressure switch 833 is detected in the RAM 93.

The control device 9 performs the pump drying control in accordance with various situations between the power-on and the power-down of the ink jet recording apparatus 1.
Hereinafter, pump drying control in various situations will be described.

[When power is turned on]
The pump drying control is executed when the power supply of the inkjet recording apparatus 1 is turned on. FIG. 8 is a flowchart in the case where the power switch 96 is turned on and the CPU 91 performs processing when the power is turned on for the deaeration device 83. When the pump drying control is executed when the power is turned on, the second liquid feed pump 829 is in a stopped state, and the supply of ink from the deaeration module 831 to the downstream side is stopped. It is in.

When detecting the ON of the power switch 96, the CPU 91 executes the pump drying control shown in FIG. 7 (step S21).
When the pump drying control is completed, the internal space of the vacuum path 836 and the hollow fiber membrane 831a of the deaeration module 831 is reduced to the lower limit pressure. The CPU 91 maintains this state until a predetermined decompression maintenance time t1 has elapsed (step S23). The reduced pressure maintaining time t1 is a time during which the dissolved oxygen in the ink in the deaeration module 831 can be sufficiently removed under a pressure equal to or lower than the upper limit pressure. The reduced pressure maintaining time t1 is input from the input operation unit 94. Can be changed as appropriate.
Until the decompression maintenance time t1 elapses, for example, the CPU 91 maintains the standby state (setup state) even if an image formation command or a maintenance command is received.
Then, when the decompression maintenance time t1 has elapsed, the CPU 91 releases the standby state and becomes ready to accept an image formation command and a maintenance command (step S25).

[Standby]
Further, the pump drying control is executed even during standby time when no image formation command or maintenance command is received. FIG. 9 is a flowchart when the CPU 91 performs pump drying control on the deaerator 83 during standby. Note that when the pump drying control is executed during this standby time, the second liquid feed pump 829 is in a stopped state and the supply of ink from the deaeration module 831 to the downstream side is stopped.

In the standby state, the CPU 91 determines the input of the electric signal ON of the pressure switch 833 (step S31). If there is no input, the CPU 91 drives the vacuum pump 832 to reduce the pressure in the vacuum path 836 to the lower limit pressure ( Step S33).
Further, when the input of the electric signal ON of the pressure switch 833 is detected, it is considered that the inside of the vacuum path 836 has reached the lower limit pressure, and the driving of the vacuum pump 832 is stopped (step S35).
And the pump drying control shown in FIG. 7 is performed, and a process is complete | finished after that.
Note that the processing in the standby state is repeatedly executed periodically.

[During image formation]
The pump drying control is also executed when image formation is performed in response to an image formation command. FIG. 10 is a flowchart when the CPU 91 performs pump drying control on the deaeration device 83 during image formation.
During image formation, the third liquid feed pump 850 periodically supplies a certain amount of ink in the intermediate tank 84 to the head 3 side. When the ink in the intermediate tank 84 decreases with this, the second liquid feed pump 829 executes the supply of ink from the sub tank 82 to the downstream side through the deaeration module 831 based on the detection of the liquid amount sensor 841. . That is, when ink discharge is started from each head 3 by image formation, the second liquid feed pump 829 is intermittently driven according to the consumption to supply ink, so that pump drying control at the time of image formation is performed. In performing the above, it is considered that ink is not sent downstream from the deaeration module 831 with insufficient deaeration. Hereinafter, pump drying control during image formation will be described based on this.

  When the CPU 91 receives the image data together with the image formation command (step S41), the CPU 91 performs the pump drying control shown in FIG. 7 before the driving of each head 3 is started using the time required for processing and storing the image data. Execute (Step S43). That is, since each head 3 is not driven, the first pump drying control is executed in a state where ink is not supplied by the liquid feed pumps 829 and 850.

When the initial pump drying control is completed, the carriage 4 is moved to the image forming position, each head 3 is driven to discharge ink, and image formation is started (step S45). Thereafter, the liquid feed pumps 829 and 850 are driven in accordance with the ink consumption, and the ink supply is executed intermittently (step S47).
In the deaeration device 83, since the first pump drying control is already executed, the vacuum path 836 of the deaeration device 83 and the internal space of the hollow fiber membrane 831a are in a state where the pressure is at least lower than the upper limit pressure.

  Then, the CPU 91 determines the input of the electric signal ON of the pressure switch 833 (step S49), and when there is no input, starts to drive the vacuum pump 832. At this time, the CPU 91 starts measuring the second pump continuous drive time t8 required to reduce the suction pressure from the upper limit pressure to the lower limit pressure by the vacuum pump 832 (step S51). Then, the process returns to step S49 again.

  On the other hand, if the input of the electrical signal ON of the pressure switch 833 is detected in step S49, the CPU 91 stops the driving of the vacuum pump 832 (step S53), and the second pump continuous driving time t8 that has been timed. Is determined (step S55).

Then, it is determined whether or not the second pump continuous drive time t8 exceeds the second determination time t5 (step S57). The second determination time t5 is a value obtained by adding a delay time as a margin to an average required time required for the vacuum pump 832 to reduce the suction pressure from the upper limit pressure to the lower limit pressure. When the time t5 is not exceeded, the vacuum pump 832 is in a good state, and when the second determination time t5 is exceeded, the vacuum pump 832 is in a slightly malfunctioning state.
The second determination time t5 can be appropriately changed by an input from the input operation unit 94.

  In addition, the measured value of the second pump continuous drive time t8 started immediately after the start of image formation is measured more than the actual time because the time measurement is started in a state where the vacuum path 836 has not risen to the upper limit pressure. Although the second pump continuous drive time t8 is shortened, the second pump continuous drive time t8 measured after the second time is the time required to reduce the suction pressure from the upper limit pressure to the lower limit pressure by the vacuum pump 832. It can be determined accurately.

If the second pump continuous drive time t8 does not exceed the second determination time t5, it is assumed that the vacuum pump 832 is in a good state, and the process proceeds to step S63.
On the other hand, when the second pump continuous drive time t8 exceeds the second determination time t5, the vacuum pump 832 further determines whether or not the third determination time t6 is exceeded (step S59). .
The third determination time t6 is longer than the second determination time t5, and when the third determination time t6 is exceeded, it indicates that the state in which the vacuum pump 832 has failed is suspected. The third determination time t6 can also be changed as appropriate by input from the input operation unit 94.

  When the second pump continuous drive time t8 exceeds the third determination time t6, the vacuum pump 832 performs control for notifying the abnormality of the vacuum pump 832 that an abnormality has occurred. As the notification control, as in the case of the pump drying control, for example, display of an abnormality notification screen on the display unit 95, lighting of a lamp, ringing of a buzzer, and the like. In this case, the process is interrupted until the vacuum pump 832 is restored.

  On the other hand, if it is determined in step S59 that the second pump continuous drive time t8 does not exceed the third determination time t6, it is assumed that the vacuum pump 832 is in an abnormal state and the pump drying control is performed when the power is turned off. The drying execution flag at the time of running is turned on, and this is recorded in the RAM 93 (step S61).

Next, the CPU 91 calculates a degassing ink consumption time t7 obtained from the ink capacity of the degassing module 831 and the ink consumption speed at the time of image formation (step S63).
The degassing ink consumption time t7 is an estimated time required for consuming all the degassed ink stored in the degassing module 831 during image formation. The degassing ink consumption time t7 is calculated by dividing the amount of ink that can be stored in the degassing module 831 by the ink consumption speed at the time of image formation.
The ink capacity of the deaeration module 831 is measured in advance and stored in a memory (not shown). As for the ink consumption speed at the time of image formation, for example, table data indicating the correspondence relationship between the number of ejected dots obtained from the image data and the ink consumption per unit time is stored in advance in a memory (not shown). It is acquired by referring to the table data from the image data received together with the command.

Next, the CPU 91 performs comparison processing according to the following equation based on the following parameters (step S65).
t7> t2 + t4 + t1
t7: Degassing ink consumption time calculated in step S63 t2: Drying time for the vacuum pump 832 in the above-described pump drying control t4: The suction pressure from the atmospheric pressure to the lower limit pressure obtained by measurement in the above-described pump drying control First pump continuous drive time t1 required for lowering: reduced pressure maintenance time during which the dissolved oxygen in the ink in the deaeration module 831 can be sufficiently removed under a pressure equal to or lower than the upper limit pressure

That is, the CPU 91 sets the lower limit from the time to dry the vacuum pump in the pump drying control and the atmospheric pressure after drying until the degassed ink in the degassing module 831 is consumed by the current image formation. It is determined whether or not the time for performing pressure reduction to the pressure and the time for performing deaeration under reduced pressure are sufficient.
If the time is insufficient (t7 ≦ t2 + t4 + t1), the process proceeds to step S69 without performing the pump drying control.
If the time is sufficient (t7> t2 + t4 + t1), the pump drying control shown in FIG. 7 is executed (step S67).
While the pump drying control is being executed, the ink supply by the second liquid supply pump 829 can be executed. However, the pump drying control is finished before all the degassed ink is supplied, and a new ink is supplied. Since the deaeration is also completed, the supply of ink with insufficient deaeration can be avoided.

Then, the CPU 91 determines whether or not the image formation has been completed (step S69). If image formation continues, the process returns to step S49 and the output of the pressure switch 833 is monitored.
When the image formation is completed, the ink supply control is also completed (step S71), and the entire process is terminated.

[During maintenance (extrusion process)]
The pump drying control is also executed during maintenance with ink supply. For example, when a relatively large amount of ink is ejected from the nozzles of each head 3 as in the extrusion process, the second and third liquid feed pumps 829 are according to the ink supply control described above, as in the image formation. , 850, ink is supplied. Accordingly, in this case as well, pump drying control is executed so that ink is not sent downstream from the deaeration module 831 with insufficient deaeration.
FIG. 11 is a flowchart when the CPU 91 performs pump drying control on the deaeration device 83 during maintenance of the extrusion process.
It should be noted that the pump drying control at the time of maintenance has many parts common to the pump drying control at the time of image formation, and the reduced pressure maintaining time t1, the drying time t2, the first pump continuous drive time t4, and the second determination time. Since t5, the third determination time t6, the deaerated ink consumption time t7, and the second pump continuous drive time t8 show the same contents, their description is omitted.

  First, the CPU 91 starts ink supply control similar to that at the time of image formation by the liquid feed pumps 829 and 850 according to the ink consumption (step S81), and starts ink ejection from the nozzles of each head 3. (Step S83).

  Then, the CPU 91 determines the input of the electric signal ON of the pressure switch 833 (step S85), and when there is no input, starts to drive the vacuum pump 832. At this time, the CPU 91 starts measuring the second pump continuous drive time t8 (step S87). Then, the process returns to step S85 again.

  On the other hand, when the input of the electric signal ON of the pressure switch 833 is detected in step S85, the CPU 91 stops the driving of the vacuum pump 832 (step S89), and the second pump continuous driving time t8 that has been timed. Is determined (step S91).

Then, it is determined whether or not the second pump continuous drive time t8 exceeds the second determination time t5 (step S93).
If the second pump continuous drive time t8 does not exceed the second determination time t5, the vacuum pump 832 proceeds to step S99.
On the other hand, when the second pump continuous drive time t8 exceeds the second determination time t5, the vacuum pump 832 further determines whether or not the third determination time t6 is exceeded (step S95). .

Then, when the second pump continuous drive time t8 exceeds the third determination time t6, control for notifying the abnormality of the vacuum pump 832 is performed. The content of the notification control is the same as during image formation.
On the other hand, if the second pump continuous drive time t8 does not exceed the third determination time t6 in the determination of step S95, the drying execution flag at the time of falling is turned on and this is recorded in the RAM 93 (step 93). S97).

Next, the CPU 91 calculates the deaeration ink consumption time t7 (step S99), and performs comparison processing according to the following equation (step S101).
t7> t2 + t4 + t1
If t7 ≦ t2 + t4 + t1, the process proceeds to step S105 without performing pump drying control.
If t7> t2 + t4 + t1, the pump drying control shown in FIG. 7 is executed (step S103).
Thereby, even if ink is supplied by the second liquid feed pump 829 during execution of pump drying control, supply of ink with insufficient deaeration can be avoided.

Then, the CPU 91 determines whether or not a specified time for continuously ejecting the extrusion process has elapsed (step S105). If the specified time has not elapsed, the process returns again to step S85 and the output of the pressure switch 833 is monitored.
When the specified time has elapsed, the ink supply control is also completed (step S107), the ink ejection from the nozzles of each head 3 is also stopped (step S109), and the entire process is completed.

[During maintenance (wipe processing)]
The pump drying control is also executed during a wiping process during maintenance that does not involve ink supply. FIG. 12 is a flowchart when the CPU 91 performs pump drying control on the deaeration device 83 during the maintenance of the wiping process.
Since only a small amount of ink is ejected during this maintenance, the second and third liquid feed pumps 829 and 850 remain stopped.

First, the CPU 91 moves the carriage 4 to the maintenance unit 7 and starts the wiping operation of the nozzle surface of each color head group by the cleaning roller of the wiping device (step S111).
Then, the pump drying control shown in FIG. 7 is executed together with the start of the wiping operation (step S113).
After the completion of the pump drying control, the process ends after waiting for completion of the wiping operation (step S115).
In the wiping process, when the wiping operation is completed, flushing is performed by each head 3, but since the number of ejections is small, ink supply is not performed.

[Nozzle missing confirmation process]
The pump drying control is also executed during the nozzle missing confirmation process that does not involve ink supply. FIG. 13 is a flowchart in the case where the CPU 91 performs pump drying control on the deaeration device 83 during the nozzle missing confirmation process.
In addition, since this nozzle missing confirmation process performs only a small amount of ink ejection, the second and third liquid feed pumps 829 and 850 remain stopped.

First, the CPU 91 moves the carriage 4 above the ink tray 71 of the maintenance unit 7 and repeatedly executes a plurality of ejection operations by each head 3. Then, the nozzle that has not been ejected by the nozzle sensor 72 is detected (step S121).
Then, the pump drying control shown in FIG. 7 is executed together with the start of the ejection operation of each head 3 (step S123).
After the completion of the pump drying control, the completion of the nozzle missing detection process for all the heads 3 is awaited (step S125), and the process ends.
In the nozzle missing confirmation process, each head 3 ejects a plurality of times. However, since ink consumption is small, ink supply is not performed.

[When power is turned off]
The pump drying control is executed when the power supply of the inkjet recording apparatus 1 is turned off. FIG. 14 is a flowchart in the case where the power switch 96 is turned OFF and the CPU 91 performs processing at the time of power-down for the deaerator 83. When the pump drying control is executed when the power is turned off, the second liquid feed pump 829 is in a stopped state, and the supply of ink from the deaeration module 831 to the downstream side is stopped. It is in.

When detecting that the power switch 96 is turned off (step S131), the CPU 91 reads the drying execution flag stored in the RAM 93 and determines whether or not the flag is in an ON state (step S133).
If the flag is OFF, the processing is terminated as it is and the power is turned off.
If the flag is ON, the pump drying control shown in FIG. 7 is executed (step S135), and then the process is terminated and the power is turned off.

  Note that the wiping process (and flushing) for each head 3 may be executed when the pump drying control in step S135 is completed or during execution.

[Technical effects in the embodiment of the invention]
In the inkjet recording apparatus 1, the control device 90 executes pump drying control for operating the vacuum pump 832 with the atmosphere release valve 834 of the deaeration device 83 being in the atmosphere release state, so that the outside air dried by the deaeration module 831 is pumped 832. The moisture in the pump 832 can be eliminated.
As a result, it is possible to satisfactorily deaerate the ink by the vacuum pump 832 and suppress the deterioration of the vacuum pump, thereby extending the life.

  In particular, the pump drying control is performed when the second liquid pump 829 is stopped, for example, when the power is turned on, when it is turned off, when neither image formation nor maintenance is being performed, during wipe processing, When the pump drying control is executed at the time of the lack confirmation process or the like, the inside of the vacuum pump 832 is realized while the specific process for avoiding the supply of ink with insufficient deaeration is unnecessary. It becomes possible.

  Further, the control device 9 of the ink jet recording apparatus 1 performs the degassing ink consumption time t7 even when the ink is supplied by the second liquid feed pump 829 as in the image forming process or the maintenance pushing process. Comparison determination is performed using the drying time t2, the first pump continuous driving time t4, and the reduced pressure maintaining time t1 as parameters. Therefore, the pump drying control is performed after determining whether or not there is time to complete the pump drying control and the degassing of new ink until all the degassed ink is sent from the degassing module 831. Therefore, the inside of the vacuum pump 832 can be dried without supplying ink that is not sufficiently deaerated.

  Further, the control device 9 of the ink jet recording apparatus 1 measures the second pump continuous drive time t8, determines whether or not the second determination time t5 is exceeded, and if so, the pump drying control is performed when the power is turned off. Therefore, the inside of the pump can be dried with respect to the vacuum pump 832 that has caused a malfunction, and the condition of the vacuum pump 832 can be improved.

  Further, the control device 9 of the ink jet recording apparatus 1 determines whether or not the second pump continuous drive time t8 exceeds the third determination time t6, and executes control for notifying the abnormality of the vacuum pump 832 when it exceeds. Therefore, the abnormality of the vacuum pump 832 can be promptly recognized by the user, and quick recovery can be achieved.

  In addition, after the pump drying control is performed, the abnormality of the vacuum pump 832 is also detected when the pressure cannot be reduced from the atmospheric pressure to the target lower limit pressure within a predetermined time (first determination time t3) by the vacuum pump. Since the notification control is executed, the abnormality of the vacuum pump 832 can be promptly recognized by the user, and quick recovery can be achieved.

[Effectiveness test]
FIG. 15 shows the result of the effect test by the execution of the pump drying control for the vacuum pump.
The effect test was carried out in an environment of room temperature 25 ° C. and humidity 38.0 to 40.0% against a diaphragm pump (NF-85.3DC (24V specification)) manufactured by KNF.
In the test method, 0.11 [ml] of water is dropped into a vacuum path connected to the diaphragm pump. This corresponds to 10 times the saturated water vapor amount of the volume of the vacuum path 836 of the inkjet recording apparatus 1.
In this state, the diaphragm pump is driven to suck the atmosphere, and after the specified time (15 seconds, 30 seconds, 45 seconds) has elapsed, the diaphragm pump is disassembled and the presence of moisture remaining inside is confirmed by hand. .

As a result, when the pump drive time was 15 seconds, moisture remained throughout the diaphragm pump, and at 30 seconds, moisture remained near the outlet of the diaphragm pump and the diaphragm.
On the other hand, in the pump driving time of 45 seconds, water was almost removed in the entire area of the diaphragm pump.
From the above results, it is considered that the drying time t2 is desirably 45 seconds or longer, and more desirably 90 seconds with a double margin.

[Confirmation test of the effect of moisture]
16 and 17 show the results of a confirmation test of the influence of moisture (water vapor) on the vacuum pump.
The above test was performed in an environment of room temperature 25 ° C. and humidity 38.0 to 40.0% against a diaphragm pump (NF-85.3DC (24V specification)) manufactured by KNF.
In the test method, steam for humidification tap water is sucked for 3 minutes in a pump drive state with respect to a vacuum path (degassing module removal) connected to the diaphragm pump.
After that, reconnect the deaeration module and change from atmospheric pressure to lower pressure limit (-92kPa (differential pressure)) and upper pressure (-90kPa (differential pressure)) to lower pressure (-92kPa (atmospheric pressure) Each time until reaching the differential pressure))) was measured three times. FIG. 16 shows the measurement result at that time.

  Next, after the above measurement, the pump drying control is executed for 90 seconds, and the lower limit pressure from the atmospheric pressure to the lower limit pressure (-92 kPa (differential pressure of atmospheric pressure)) and the upper limit pressure (-90 kPa (differential pressure of atmospheric pressure)). The time to reach (-92 kPa (differential pressure of atmospheric pressure)) was measured three times each. FIG. 17 shows the measurement result at that time.

As a result, the time required to reach the lower limit pressure from the atmospheric pressure immediately after sucking water vapor was 52 seconds on average, and the time required to reach the lower pressure limit from the upper pressure immediately after sucking water vapor was 31 seconds on average.
In addition, the time from the atmospheric pressure to the lower limit pressure after the pump drying control is executed is 23.6 seconds on average, and the time from the upper limit pressure immediately after sucking water vapor to the lower pressure is 9 seconds on average. The influence of moisture adhering to the inside was remarkable in the diaphragm pump, and it became clear that there was a large delay in decompression.
Based on these results, when setting the timeout until reaching the lower limit pressure from the atmospheric pressure in the vacuum pump on the premise that the pump drying control is not performed, 240 seconds, which is approximately four times the average value of FIG. When setting a timeout for reaching the lower limit pressure from the upper limit pressure in the vacuum pump on the premise that the pump drying control is not performed, it is desirable to set 120 seconds, which is approximately four times the average value in FIG.

[Others]
The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, in the various maintenance processes described above, the case where the pump drying control is executed in parallel with the maintenance process is illustrated, but the present invention is not limited thereto, and the pump drying control may be executed after the maintenance process is completed. .

The pump drying control may determine whether or not to execute the second liquid feeding pump 829 according to the driving time. That is, it is determined whether or not the second liquid feed pump 829 continuously delivers liquid for a predetermined time or more, and if it exceeds, the deaerator 83 is controlled so as to execute the pump drying control. Also good.
Note that “the second liquid supply pump 829 continuously supplies liquid for a predetermined time or more” means that the ink supply control duration in which the second liquid supply pump 829 intermittently supplies liquid is used. It is the meaning which shows that.
In this case, there is no restriction on when to execute the pump drying control. For example, the pump drying control may be started during liquid feeding when the liquid feeding exceeds a certain time, or when the liquid feeding exceeds a certain time, the drying execution flag at the time of falling is turned ON and the water is lowered. In this case, pump drying control may be executed.

Further, the ink jet recording apparatus 1 of the above embodiment includes the deaeration device 83 and the second liquid feeding pump 829 for each head group corresponding to the ink of each color, and independently for each color without interfering with each other. However, the present invention is not limited to this.
That is, the deaeration device 83 corresponding to the ink of each color may perform pump drying control so as to be related to each other. For example, when performing pump drying control during image formation, one or more colors that are not used for image formation are specified in advance from the image data, and only the deaeration device 83 corresponding to the color performs pump drying control during image formation. You may control to perform. In that case, it is possible to omit the comparison determination using the degassing ink consumption time t7, the drying time t2, the first pump continuous driving time t4, and the reduced pressure maintaining time t1 as parameters.

  Conversely, from the image data, one or more colors having the highest ink usage in image formation are selected in advance from the top, and only the deaerator 83 corresponding to the color executes pump drying control after image formation. You may control as follows. In that case, it is not necessary to perform pump drying control during image formation.

In the ink jet recording apparatus 1 of the above embodiment, the case where the degassing device 83 and the second liquid feeding pump 829 are provided for each head group corresponding to the ink of each color is illustrated, but the present invention is not limited to this. Absent.
For example, it is good also as a structure provided with the deaeration apparatus 83 and the 2nd liquid feeding pump 829 for every some head 3. FIG.
In that case, pump drying control may be executed independently for each deaeration device 83 of each head 3.
For each head 3, one or a plurality of heads 3 that are not used for image formation are specified in advance from the image data, and only the deaeration device 83 corresponding to the head 3 performs pump drying control during image formation. You may control to. Even in this case, it is possible to omit the comparison determination using the degassing ink consumption time t7, the drying time t2, the first pump continuous driving time t4, and the reduced pressure maintaining time t1 as parameters.

  In addition, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  As described above, the present invention is suitable for providing an ink jet recording apparatus that can reduce the influence of ink moisture and a control method thereof.

1 Inkjet recording device 3 Head (inkjet head)
4 Carriage 5 Main scanning device 6 Nozzle moisturizing unit 7 Maintenance unit 8 Ink supply device 9 Control device 20 Conveying device 82 Sub tank (ink tank)
83 Deaerator 84 Intermediate tank 86 Negative pressure forming unit 9 Controller 96 Power switch 100 Frame 811 Ink flow path 814 First liquid pump 829 Second liquid pump 850 Third liquid pump 823, 835 Ink flow Channel 831 Deaeration module 831a Hollow fiber membrane 832 Vacuum pump 833 Pressure switch 834 Atmospheric release valve 835 Ink channel 836 Vacuum channel 837 Branch channel 842, 843, 844 Ink channel 845 Ink channel

Claims (26)

A deaeration module provided in the middle of an ink supply path for supplying ink from the ink tank to the inkjet head;
A vacuum pump that depressurizes the ink through the gas permeable membrane of the degassing module;
An atmosphere release valve capable of switching between an airtight state and an atmosphere release state in a path connecting the deaeration module and the vacuum pump;
A controller for controlling the vacuum pump and the air release valve;
The ink jet recording apparatus, wherein the control device performs pump drying control for operating the vacuum pump with the air release valve in an air release state.   The inkjet recording apparatus according to claim 1, further comprising a liquid feed pump that supplies ink to the inkjet head side through the deaeration module.   3. The ink jet recording apparatus according to claim 2, wherein the control device performs the pump drying control while the liquid feed pump is stopped.   4. The ink jet recording apparatus according to claim 3, wherein the control device executes the pump drying control at the time of maintenance of the ink jet head or immediately after the end of the maintenance.   4. The ink jet recording apparatus according to claim 3, wherein the control device performs the pump drying control when the liquid feeding pump continuously feeds liquid for a predetermined time or more. The control device performs pressure maintenance control to start driving at the upper limit pressure and stop driving at the lower limit pressure with respect to the vacuum pump,
The controller is
[Degassing ink consumption time determined by the ink capacity of the degassing module and the ink consumption speed at the time of image formation]> ([specified drying time in the pump drying control] + [degassing the ink in the degassing module In order to maintain the pressure below the upper limit pressure] + [first pump continuous drive time required to reduce the suction pressure from the atmospheric pressure to the lower limit pressure by the vacuum pump])) 3. The ink jet recording apparatus according to claim 2, wherein pump drying control is performed after the lower limit pressure is reached by control. The control device performs pressure maintenance control to start driving at the upper limit pressure and stop driving at the lower limit pressure with respect to the vacuum pump,
The controller is
When the second pump continuous drive time required to reduce the suction pressure from the upper limit pressure to the lower limit pressure by the vacuum pump exceeds a predetermined determination time, the main power of the ink jet recording apparatus is turned off and the pump is dried at the fall. Control is performed, The inkjet recording device as described in any one of Claim 1 to 6 characterized by the above-mentioned.   8. The ink jet recording apparatus according to claim 7, wherein the control device performs a wiping process of the ink jet head in accordance with the pump drying control at the time of falling.   The ink jet recording according to claim 7 or 8, wherein the controller notifies the abnormality of the vacuum pump when the second continuous pump driving time exceeds another determination time longer than the determination time. apparatus.   The said control apparatus alert | reports the abnormality of the said vacuum pump when the pressure reduction to the target minimum pressure cannot be carried out within the fixed time predetermined by the said vacuum pump after the said pump drying control. The ink jet recording apparatus according to any one of 1 to 9. The deaeration module, the vacuum pump, and the air release valve are individually provided corresponding to a plurality of colors of ink,
The control device specifies one or more colors that are not used from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the ink of the specified color at the time of image formation. The ink jet recording apparatus according to claim 2. The deaeration module, the vacuum pump, and the air release valve are individually provided corresponding to a plurality of colors of ink,
The control device identifies one or more colors having the highest ink usage from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the specified color ink after image formation. The inkjet recording apparatus according to claim 2, wherein the inkjet recording apparatus is performed. The deaeration module, the vacuum pump, and the atmosphere release valve are individually provided corresponding to a plurality of inkjet heads,
The control device identifies one or more inkjet heads that are not used from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the identified inkjet head during image formation. The ink jet recording apparatus according to claim 2. A deaeration module provided in the middle of an ink supply path for supplying ink from the ink tank to the inkjet head;
A vacuum pump that depressurizes the ink through the gas permeable membrane of the degassing module;
An atmosphere release valve capable of switching between an airtight state and an atmosphere release state in a path connecting the deaeration module and the vacuum pump;
A control method for an ink jet recording apparatus comprising a control device for controlling the vacuum pump and the air release valve,
The method for controlling an ink jet recording apparatus, wherein the control device performs pump drying control for operating the vacuum pump with the air release valve in an air release state.   15. The method of controlling an ink jet recording apparatus according to claim 14, further comprising a liquid feed pump that supplies ink to the ink jet head side through the deaeration module.   16. The method of controlling an ink jet recording apparatus according to claim 15, wherein the control device performs the pump drying control while the liquid feed pump is stopped.   The method of controlling an ink jet recording apparatus according to claim 16, wherein the control device executes the pump drying control at the time of maintenance of the ink jet head or immediately after the end of the maintenance.   17. The method of controlling an ink jet recording apparatus according to claim 16, wherein the control device performs the pump drying control when the liquid supply pump continuously supplies liquid for a predetermined time or more. The control device performs pressure maintenance control to start driving at the upper limit pressure and stop driving at the lower limit pressure with respect to the vacuum pump,
The controller is
[Degassing ink consumption time determined by the ink capacity of the degassing module and the ink consumption speed at the time of image formation]> ([specified drying time in the pump drying control] + [degassing the ink in the degassing module In order to maintain the pressure below the upper limit pressure] + [first pump continuous drive time required to reduce the suction pressure from the atmospheric pressure to the lower limit pressure by the vacuum pump])) 16. The method of controlling an ink jet recording apparatus according to claim 15, wherein pump drying control is performed after reaching the lower limit pressure by control. The control device performs pressure maintenance control to start driving at the upper limit pressure and stop driving at the lower limit pressure with respect to the vacuum pump,
The controller is
When the second pump continuous drive time required to reduce the suction pressure from the upper limit pressure to the lower limit pressure by the vacuum pump exceeds a predetermined determination time, the main power of the ink jet recording apparatus is turned off and the pump is dried at the fall. 20. The method for controlling an ink jet recording apparatus according to claim 14, wherein control is executed.   21. The method of controlling an ink jet recording apparatus according to claim 20, wherein the control device performs a wiping process of the ink jet head in accordance with pump drying control at the time of falling.   The ink jet recording according to claim 20 or 21, wherein the controller notifies the abnormality of the vacuum pump when the second continuous pump driving time exceeds another determination time longer than the determination time. Control method of the device.   The said control apparatus alert | reports the abnormality of the said vacuum pump when the pressure reduction to the target minimum pressure cannot be carried out within the fixed time predetermined by the said vacuum pump after the said pump drying control. The method for controlling an ink jet recording apparatus according to any one of 14 to 22. The deaeration module, the vacuum pump, and the air release valve are individually provided corresponding to a plurality of colors of ink,
The control device specifies one or more colors that are not used from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the ink of the specified color at the time of image formation. 16. A method for controlling an ink jet recording apparatus according to claim 14 or 15. The deaeration module, the vacuum pump, and the air release valve are individually provided corresponding to a plurality of colors of ink,
The control device identifies one or more colors having the highest ink usage from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the specified color ink after image formation. 16. The method of controlling an ink jet recording apparatus according to claim 14, wherein the control method is performed. The deaeration module, the vacuum pump, and the atmosphere release valve are individually provided corresponding to a plurality of inkjet heads,
The control device identifies one or more inkjet heads that are not used from image data for image formation, and performs pump drying control on the vacuum pump corresponding to the identified inkjet head during image formation. 16. A method for controlling an ink jet recording apparatus according to claim 14 or 15.

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