JP6547759B2 - Ink supply device and inkjet recording device - Google Patents

Description

  The present invention relates to an ink supply device and an inkjet recording device.

  Conventionally, an ink jet recording apparatus supplies an ink from an ink tank to an ink jet head, and discharges the ink as fine droplets from a nozzle of the ink jet head toward the recording medium to form an image on the recording medium. In the ink jet recording apparatus, a negative pressure forming unit is provided between the ink tank and the ink jet head, and the negative pressure forming unit makes the inside of the nozzle of the ink jet head negative pressure, and the ink is supplied from the nozzle of the ink jet head at the time of ink supply. Some are configured to not drip.

  The negative pressure forming unit is configured to store the ink supplied from the ink tank, adjust the internal pressure according to the stored amount of ink, and make the inside of the ink jet head negative pressure, for example, using a damper or the like. Be In order to set the negative pressure inside the negative pressure forming part, the ink is supplied into the negative pressure forming part in the open state to fill the negative pressure forming part with the ink, and then the negative pressure forming part is sealed and then the inside is formed. Drain the ink. Therefore, the ink jet recording apparatus provided with the negative pressure forming portion needs to be configured to be able to supply and discharge the ink into the negative pressure forming portion.

As such a configuration, for example, an inkjet recording apparatus is provided in which a bidirectional pump capable of sending ink in both forward and reverse directions is connected to a negative pressure forming unit (for example, Patent Document 1) reference).
Further, for example, in the negative pressure forming unit, a pump for feeding the ink in the forward direction and a pump for feeding the ink in the reverse direction are arranged in parallel on the ink path communicating with the negative pressure forming unit. Patent Document 2 discloses an ink jet recording apparatus configured to supply and discharge ink.

JP 2007-98594 A JP 2014-46515 A

  However, in the configuration using the bi-directional pump, there is a problem that the cost of the device increases because the bi-directional pump is expensive, and in the configuration using the two pumps, There is a problem that the size of the apparatus is increased because the number of members is increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink supply apparatus and an inkjet recording apparatus capable of adjusting the pressure in the negative pressure forming portion and suppressing the increase in size and cost of the apparatus.

In order to solve the above problems, the invention according to claim 1 is:
An ink supply apparatus for supplying ink to an ink jet head, comprising:
A first ink tank for storing ink;
A second ink tank for storing ink supplied from the first ink tank;
A first ink flow path communicating the first ink tank and the second ink tank;
A first liquid transfer pump provided in the first ink flow path to transfer the ink in the first ink tank to the second ink tank;
A first on-off valve provided between the first ink tank and the first liquid supply pump in the first ink flow path and opening and closing the first ink flow path;
A negative pressure forming unit that stores ink supplied from the second ink tank and supplies the ink to the ink jet head, and adjusting the internal pressure to make the inside of the ink jet head negative pressure state;
A pressure detection unit that detects the pressure in the negative pressure formation unit;
A second ink flow path communicating the second ink tank and the negative pressure forming portion;
A second liquid transfer pump provided in the second ink flow path to transfer the ink in the second ink tank to the negative pressure forming portion;
Communication is made between the second liquid transfer pump and the negative pressure forming portion in the second ink flow path, and between the first on-off valve and the first liquid transfer pump in the first ink flow path. The third ink flow path,
A second on-off valve provided in the third ink flow path to open and close the third ink flow path;
Driving control of the first liquid transfer pump, the first on-off valve, the second liquid transfer pump, and the second on-off valve based on the pressure in the negative pressure forming unit detected by the pressure detection unit And a control unit for adjusting the pressure in the negative pressure forming unit.

The invention described in claim 2 is the ink supply device according to claim 1, wherein
The control unit closes the first on-off valve and opens the second on-off valve when the pressure in the negative pressure forming unit detected by the pressure detection unit is higher than a first predetermined value, By feeding the ink by the first feed pump, the negative pressure forming unit sends the ink to the second ink tank via the third ink flow path, and the pressure in the negative pressure forming unit is determined. It is characterized by adjusting.

The invention described in claim 3 is the ink supply device according to claim 2, wherein
The control unit closes the second on-off valve when the pressure in the negative pressure forming unit detected by the pressure detection unit is lower than a second predetermined value lower than the first predetermined value, By feeding the ink by the second feed pump, the ink is sent from the second ink tank to the negative pressure forming unit via the second ink flow path, and the pressure in the negative pressure forming unit is It is characterized by adjusting.

The invention described in claim 4 is the ink supply device according to any one of claims 1 to 3, wherein
The apparatus may further include a third on-off valve provided between the second ink tank and the second liquid supply pump in the second ink flow path and opening and closing the second ink flow path.

The invention described in claim 5 is the ink supply device according to any one of claims 1 to 4, wherein
The negative pressure forming portion biases the film member from the inside to the outside of the container body, the container body having an opening formed therein and storing the ink, the flexible film member covering the opening, and And an elastic member.

The invention described in claim 6 is the ink supply device according to any one of claims 1 to 5, wherein
The apparatus may further comprise a degassing module provided between the second ink tank and the second liquid feed pump in the second ink flow path.

The invention according to claim 7 is an ink jet recording apparatus, wherein
The ink supply device according to any one of claims 1 to 6,
And an ink jet head for discharging the ink supplied by the ink supply device.

  According to the present invention, it is possible to provide an ink supply apparatus and an ink jet recording apparatus capable of adjusting the pressure in the negative pressure forming portion and suppressing the increase in size and cost of the apparatus.

FIG. 1 is a perspective view of an inkjet recording apparatus. It is a schematic diagram which shows the outline of an ink supply apparatus. FIG. 2 is a block diagram showing a control system of the inkjet recording apparatus. It is a flowchart which shows the negative pressure formation process performed after ink initial introduction or after pressurization maintenance. It is a flowchart which shows the negative pressure formation process in printing operation.

  Hereinafter, an ink supply apparatus and an inkjet recording apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated example. In the following description, components having the same function and configuration are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 1, the inkjet recording apparatus 1 has, for example, a transport device 2 for transporting the recording medium along the horizontal direction, and a plurality of heads 3 for ejecting ink from above onto the transported recording medium (see FIG. 2). A main scanning device 5 that conveys the carriage 4 along a horizontal direction orthogonal to the conveyance direction of the recording medium, and a maintenance unit 7 that performs maintenance on the respective heads 3 mounted on the carriage 4; A nozzle moisturizing unit 6 for moisturizing the nozzles of each head 3 mounted on the carriage 4, an ink supply device 8 (see FIG. 2) for supplying ink to each head 3 mounted on the carriage 4, and the entire support And a frame 100 that
In the following description, the direction which is the horizontal direction along the conveyance direction of the recording medium is the Y-axis direction, and the horizontal direction is the direction along the conveyance direction of the carriage 4 the X-axis direction or the main scanning direction, the vertical The direction is sometimes called the Z-axis direction.

[Conveying device]
The transport device 2 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 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 transport belt 23 is formed in an endless shape and is bridged between the driving roller 21 and the driven roller. When the drive roller 21 rotates, the transport belt 23 circulates between the drive roller 21 and the driven roller, transports the recording medium placed on the upper surface in the transport direction F along the Y-axis direction, and drives When the rotation of the roller 21 is stopped, the rotation between the two rollers is stopped, and the conveyance of the recording medium is stopped.
The drive motor 22 rotates the drive roller 21 by a predetermined amount to transport the recording medium by a predetermined distance in the transport direction F and stops the head when the head 3 completes one scan for one direction along the X-axis direction. When 3 starts and ends scanning in the direction opposite to the main scanning direction X, the driving roller 21 is rotated again by a predetermined amount, and the recording medium is conveyed by a predetermined distance in the conveying direction F and stopped repeatedly. The medium is conveyed intermittently.
In addition to paper and cloth, it is possible to use resin films, metals, etc. as the recording medium.

[flame]
As shown in FIG. 1, the frame 100 has a rectangular main body 101 extending along the X-axis direction, a first base 102 supporting one end in the X-axis direction of the main body 101, and the main body 101. And a second base portion 103 for supporting 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 portion 101 stores and holds a pair of carriage rails 51, 51 of the main scanning device 5 described later in the X axis direction, and the carriage 4 is in the main body portion 101 along the X axis direction. It is transported.
The first base portion 102 and the second base portion 103 are disposed on both sides in the X-axis direction across the above-described transfer device 2, and the main body portion 101 is provided above the transfer device 2. As a result, while the carriage 4 is transported in the direction orthogonal to the transport direction of the recording medium by the transport device 2, it is possible to discharge the ink from each of the heads 3 mounted on the carriage 4 to perform image formation.

[Main scanning device and carriage]
The main scanning device 5 includes a pair of rod-like carriage rails 51, 51 supported so as to extend along the X-axis direction inside the body portion 101 of the frame 100. The pair of carriage rails 51, 51 is provided to straddle the upper side of the transport belt 23 of the transport device 2. A box-shaped carriage 4 is supported by the carriage rails 51, 51 so as to be capable of reciprocating in the X-axis direction.

The carriage 4 is a substantially rectangular housing whose upper portion is opened, and a plurality of heads 3 are mounted on the bottom plate thereof. The carriage 4 has arms 42 and 42 extending toward both sides in the Y-axis direction at upper portions of both side surfaces in the Y-axis direction, and the respective arm parts 42 and 42 respectively extend through the carriage guide 51 via linear guides. It is placed on the upper portion 51, and is thereby slidable along the X-axis direction on the carriage rails 51, 51.
In addition, linear motors are provided between the carriage rails 51 and 51 and the arms 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 a coil on the stator side. A transport operation along the X-axis direction is given.

[Maintenance department]
The maintenance unit 7 performs maintenance of each head 3 at the time of non-recording operation. The maintenance unit 7 is provided on one end side of the carriage rails 51 and 51 while being separated from the transport device 2. That is, maintenance is carried out in a state where the carriage 4 has moved to a position where one end of the carriage rails 51, 51 faces the maintenance unit 7.
The maintenance unit 7 includes a cleaning device that wipes off the dirt on the heads 3 and an ink tray 71 (see FIG. 2) that serves as a receiving tray when the heads 3 to be maintained discharge ink.
The cleaning device is mainly constituted by a cleaning roller rotatable around a rotation axis along the X-axis direction in sliding contact with the head 3 and a roller conveyance mechanism for conveying the cleaning roller along the Y-axis direction The width of the cleaning roller in the X-axis direction is set to enable wiping of three color head groups out of nine color head groups mounted on the carriage 4. Cleaning of all the heads 3 is performed by the movement operation. And thereby, clogging of the nozzle by solidification of ink is prevented.
Further, the discharge of the ink to the ink tray 71 at the time of maintenance is performed by the ink supply pressure of the ink supply device 8, whereby the clogging of the ink flow path in the head 3 can be eliminated.

[Nozzle moisturizer]
The nozzle moisturizing portion 6 is provided on the other end side of the carriage rails 51, 51 by being separated from the transport device 2. That is, at the time of non-recording operation, the carriage 4 moves to the opposing position with the nozzle moisturizing portion 6 at the other end of the carriage rails 51, 51, and moistens the nozzles of each head 3 in this state.

[Ink supply device]
The ink jet recording apparatus 1 includes an ink supply device 8 as shown in FIG. 2 for each color.
As shown in FIG. 2, the ink supply device 8 includes, for example, a main tank (first ink tank) 81 as a storage container for storing ink as a liquid, and a sub tank (second ink) to which ink is supplied from the main tank 81. The ink tank 82, the degassing device 83 provided on the ink supply direction downstream side of the sub tank 82, the negative pressure forming unit 86 provided on the ink supply direction downstream side of the degassing device 83, and each head 3 And a common flow path 87 in which the first port 341 of each head 3 is connected in parallel in order to supply ink.

The main tank 81 is a substantially rectangular container opened to the atmosphere, and stores ink. The main tank 81 is removable from the ink jet recording apparatus 1 so that it can be replaced when empty. In the present embodiment, the main tank 81 has a substantially rectangular parallelepiped shape, but is not limited thereto. For example, the main tank 81 may have a cylindrical shape.
Further, at the upper part of the main tank 81, an air release pipe 816 for maintaining the inside of the main tank 81 at atmospheric pressure is attached. The air release pipe 816 is attached with a filter 817 for preventing intrusion of dust, dirt and the like from the outside.
In the vicinity of the bottom of the main tank 81, a remaining amount sensor 815 for detecting whether the ink is empty is provided.

  Although one main tank 81 is provided in the illustrated example, two main tanks may be provided. In this case, the ink supply from the other main tank 81 is possible even when one side becomes empty and at the time of replacement thereof, so that interruption of the recording operation of the inkjet recording apparatus 1 can be avoided. Become. In addition, the number of mounted individuals of the main tank 81 may be three or more.

A first ink flow passage 811 is provided between the main tank 81 and the sub tank 82, one end of which is in communication with the main tank 81 and the other end of which is in communication with the sub tank 82.
The first ink flow path 811 is provided with a first liquid sending pump 814 for sending the ink in the main tank 81 to the sub tank 82. The first liquid feed pump 814 is a unidirectional pump that feeds ink in one direction, and more specifically, for example, a diaphragm pump can be used. The diaphragm pump can use a perfluoroelastomer excellent in ink resistance for the liquid transfer film, and does not generate a shear load on the ink at the time of liquid transfer, so it can be used regardless of the type of ink, and Control of the amount is also preferred because it is easy.
In addition, a first on-off valve 812 which is a solenoid valve capable of switching the open / close state of the first ink flow path 811 is provided between the main tank 81 and the first liquid supply pump 814 in the first ink flow path 811 It is done.
A filter 813 is provided between the main tank 81 and the first on-off valve 812 in the first ink flow path 811 for removing contaminants such as dust and dirt from the ink. The position at which the filter 813 is provided is not limited to this, and may be provided between the sub tank 82 and the degassing device 83 in the second ink flow path 823 described later.

The sub tank 82 is a substantially rectangular parallelepiped container opened to the atmosphere, and stores the ink supplied from the main tank 81.
In addition, an air release pipe 824 for maintaining the pressure in the sub tank 82 at the atmospheric pressure is attached to the upper portion of the sub tank 82. The air release pipe 824 is attached with a filter 825 for preventing intrusion of dust, dirt and the like from the outside.
Further, since the ink in the sub tank 82 is sent to the downstream side from the bottom through the second ink flow path 823, it is possible to remove air bubbles from the ink supplied to the downstream side of the sub tank 82.

Further, in the sub tank 82, first to third liquid level sensors 826 to 828 for detecting the position of the liquid level of the ink are provided.
Each of the first to third liquid level sensors 826 to 828 is a float type sensor having a float, and can detect whether the liquid level is above or below a predetermined position from the height of the float. .

A second ink flow passage 823 is provided between the sub tank 82 and the degassing device 83, one end communicating with the sub tank 82 and the other end communicating with the negative pressure forming portion 86. Accordingly, the ink in the sub tank 82 can be supplied to the negative pressure forming unit 86 through the second ink flow path 823.
The second ink flow path 823 is provided with a second liquid sending pump 836 for sending the ink in the sub tank 82 to the negative pressure forming unit 86. The second liquid feed pump 836 is a unidirectional pump for feeding the ink in one direction, and the same one as the first liquid feed pump 814 can be used.
Further, a degassing device 83 is provided between the sub tank 82 and the second liquid feed pump 836 in the second ink flow path 823.

The degassing device 83 includes a degassing module 831 provided on the second ink flow path 823, a vacuum pump 832 for drawing a vacuum on the degassing module 831, and a vacuum for detecting the pressure in the degassing module 831. A pressure sensor 833 and an air release valve 834 which is a solenoid valve for releasing the inside of the degassing module 831 to the atmospheric pressure are provided.
The degassing module 831 has a configuration including a vacuum container in which vacuuming is performed by a vacuum pump 832, and a hollow fiber membrane that allows ink to pass inside or outside in the vacuum container, and the inside or the outside of the hollow fiber membrane is By vacuuming, the dissolved gas in the ink is sucked inward or outward through the hollow fiber membrane.
The vacuum pressure sensor 833 is a detection means for measuring whether the pressure has been reduced to a target pressure during vacuuming. Further, when the power of the inkjet recording apparatus 1 is shut off, the air release valve 834 is controlled to open so that the degassing module 831 changes from vacuum to atmospheric pressure for maintenance of the degassing module 831.

  In addition, a third on-off valve 835, which is a solenoid valve capable of switching the open / close state of the second ink flow passage 823, between the degassing device 83 and the second liquid feed pump 836 in the second ink flow passage 823. It is provided.

Further, a three-way switching valve 848 is provided between the second liquid feed pump 829 and the negative pressure forming portion 86 in the second ink flow path 823. The three-way switching valve 848 is also connected to a bypass flow passage 854 described later that supplies ink to the head 3 side without the negative pressure forming portion 86, and connects the sub tank 82 and the negative pressure forming portion 86; It is possible to switch to a state in which the sub tank 82 and the head 3 are connected via the bypass channel 854.
That is, by this switching, it is possible to execute the supply and recovery of ink to the negative pressure forming unit 86 and the supply and recovery of ink to the head 3 side (strictly speaking, the common flow path 87). And can be switched.

The negative pressure forming portion 86 includes a rectangular container main body 861 having a large opening at its front surface and storing ink, a film member 862 made of a flexible resin film covering the opening of the container main body 861, and a container main body 861. It mainly comprises a spring member (elastic member) 863 for biasing the center of the film member 862 from the inside to the outside.
In addition, since the film member 862 has its central portion pushed outward by a spring, the film member 862 is in a tensioned state with a substantially conical shape projecting outward.

  Further, a communication pipe 864 communicating with the inside of the container main body 861 and extending upward is provided on the upper portion of the container main body 861 of the negative pressure forming portion 86. A liquid level sensor 865 is attached to an end of the communication pipe 864 on the container main body 861 side, and a pressure sensor (pressure detection unit) 866 is attached to an upper end of the communication pipe 864. A horizontally extending branch pipe 867 whose one end is opened to the atmosphere is connected to an intermediate portion of the communication pipe 864, and an open valve 868 for opening and closing the branch pipe 867 is provided in the middle of the branch pipe 867; An air filter 869 for filtering is provided.

  These components are used when supplying ink into the container main body 861 to adjust the inside to a predetermined negative pressure state. That is, ink is supplied into the container main body 861 until the liquid level sensor 865 detects the liquid level with the open valve 868 open. Thereby, the ink is filled in the container main body 861 under the same pressure condition as the atmospheric pressure. Thereafter, the release valve 868 is closed to recover the ink from within the container body 861 until the pressure sensor 866 indicates the target negative pressure. Thus, the interior of each head 3 can be brought into a predetermined negative pressure state through the negative pressure forming portion 86.

Here, a third ink flow path 881 is provided between the second ink flow path 823 and the first ink flow path 811. Specifically, the third ink flow path 881 is between the second liquid feed pump 829 and the negative pressure forming portion 86 in the second ink flow path 823 (more specifically, the second liquid feed pump 829 and the three-way Between the switching valve 848 and the first on-off valve 812 in the first ink flow path 811 and the first liquid feed pump 814 are communicated.
The third ink flow passage 881 is provided with a second opening / closing valve 882 which is a solenoid valve capable of switching the open / close state of the third ink flow passage 881.
Further, in the third ink flow passage 881, a relief valve 883 is provided between a junction with the second ink flow passage 823 and the second on-off valve 882. Thus, when the predetermined pressure is exceeded in the third ink flow path 881, the ink can be returned to the sub tank 82.

By providing the third ink flow path 881 and the second on-off valve 882, the inside of the negative pressure forming unit 86 is transferred using the first liquid transfer pump 814 that transfers the ink in the main tank 81 to the sub tank 82. It can be in a negative pressure state.
That is, as described above, after the container main body 861 of the negative pressure forming unit 86 is filled with ink and sealed at the same pressure as the atmospheric pressure, the first on-off valve 812 is closed and the second on-off valve 882 is opened. The first liquid feed pump 814 feeds the ink. By the liquid feeding operation of the first liquid feeding pump 814, the ink is drawn from the negative pressure forming portion 86 side via the third ink flow path 881, not from the main tank 81 side. Thus, the ink in the negative pressure forming unit 86 can be made to flow into the sub tank 82 through the third ink flow path 881, and the ink is recovered from the inside of the container main body 861 of the negative pressure forming unit 86. The inside of 861 can be made into a negative pressure state. In addition, since the third on-off valve 835 provided in the second ink flow passage 823 is in the closed state, the third on-off valve is formed at the junction of the second ink flow passage 823 and the third ink flow passage 881. The inflow of the ink from the 835 side to the third ink channel 881 can be prevented, and the ink in the negative pressure forming portion 86 can be efficiently recovered. By setting the inside of the negative pressure forming portion 86 to a negative pressure state, the inside of each head 3 connected to the negative pressure forming portion 86 via the common flow path 87 can be set to a negative pressure state.
As described above, for maintaining the inside of the head 3 at a negative pressure, for example, when the inside of the nozzle is at atmospheric pressure, the ink is likely to leak from the nozzle, and the ink easily adheres to the periphery of the nozzle. Is likely to occur, and this is to prevent this.
Note that the target pressure to be a negative pressure can be controlled by adjusting the amount of ink collected in the container main body 861.

A common flow in which one end communicates with the negative pressure forming portion 86 between the negative pressure forming portion 86 and the nine heads 3 and the other end branches into all the first ports 341 of the nine heads 3 and is in communication A passage 87 is provided.
The common flow passage 87 is provided with a protection valve 871 which is a solenoid valve capable of switching the open / close state of the common flow passage 87.

  Further, the common flow path 87 is connected with a waste liquid flow path 872 communicating with a waste liquid tank (not shown). A first waste liquid valve 873 and a second waste liquid valve 876, which are electromagnetic valves capable of switching the open / close state of the waste liquid flow path 872, are provided in the waste liquid flow path 872, and when filling the common flow path 87 with ink. The first waste fluid valve 873 and the second waste fluid valve 876 can be opened to discharge the ink for discharging air bubbles. As a result, air bubbles that cause ink discharge failure can be removed, and stable discharge can be performed.

The common flow path 87 is connected to the first port 341 of each head 3 via the recording operation valve 874 which is an electromagnetic valve capable of switching the open / close state.
In addition, the second ports 342 of the heads 3 are connected in parallel between the first waste liquid valve 873 and the second waste liquid valve 876 in the waste liquid flow path 872 via the check valve 875, respectively. . The desired recording operation valve 874 is opened, the first waste fluid valve 873 is closed, and the second waste fluid valve 876 is opened. It can be discharged.

  A bypass channel 854 is provided between the second ink channel 823 and the common channel 87. Specifically, one end of the bypass flow passage 854 is connected to the three-way switching valve 848 in the second ink flow passage 823, and the other end is in communication between the protection valve 871 and the heads 3 in the common flow passage 87. doing.

  In the configuration of the ink supply device 8, the portion on the negative pressure forming portion 86 side of the junction of the second ink flow path 823 and the third ink flow path 881 is mounted on the carriage 4. Here, the ink in the ink supply device 8 may also move by the carriage 4 scanning in the X-axis direction, but since the third on-off valve 835 is provided in the second ink flow path 823, By setting this in the closed state, movement of the ink in the ink supply device 8 is suppressed, and stable ink discharge can be performed.

FIG. 3 is a block diagram showing a control system of the inkjet recording apparatus 1. Although the control unit 9 described in FIG. 3 controls the entire inkjet recording apparatus 1, only the configuration of the ink supply device 8 is illustrated here, and the other configurations are omitted. Also, only one of the plurality of configurations is illustrated.
As shown in FIG. 3, the control unit 9 is connected to each unit constituting the ink supply device 8 and controls each unit constituting the ink supply device 8. Based on the pressure in negative pressure forming unit 86 detected by pressure sensor 866, control unit 9 controls first liquid feed pump 814, first on-off valve 812, second liquid feed pump 836, second on-off valve 882, and the like. The drive control of the 3rd on-off valve 835 is carried out, respectively. Here, in the present invention, “drive control” refers to not only starting or stopping the liquid feeding or adjusting the flow rate in the liquid feeding pump, but also when the liquid feeding has already been started or stopped. Includes maintaining the state or maintaining the flow rate already set, and opening and closing the on-off valve not only opening or closing, but also if the state is already in the open or closed state Shall include maintaining.
The control unit 9 includes a CPU 91, a RAM 92, a ROM 93, and the like. The CPU 91 reads and executes various programs, data, and the like corresponding to the processing content from the storage device such as the ROM 93, and controls the operation of each unit of the ink supply device 8 according to the processing content executed. The RAM 92 temporarily stores various programs and data to be processed by the CPU 91. The ROM 93 stores various programs and data read by the CPU 91 and the like.

Specifically, when the pressure in negative pressure forming unit 86 detected by pressure sensor 866 is higher than a first predetermined value, control unit 9 closes first on-off valve 812 and the second on-off valve. 882 is opened, and the ink is fed by the first feed pump 814, whereby the ink is sent from the negative pressure forming unit 86 to the sub tank 82 via the third ink flow path 881 to thereby produce the inside of the negative pressure forming unit 86. Adjust the pressure of Here, in the present invention, “close the on-off valve” is to close the on-off valve when the on-off valve is in the open state, and maintain the state when the on-off valve is already in the closed state. . Further, in the present invention, “open the on-off valve” is to open the on-off valve when the on-off valve is in the closed state, and maintain the state when the on-off valve is already in the open state.
Such control is performed when the pressure in the negative pressure forming unit 86 is higher than the first predetermined value, for example, an atmospheric pressure state or a positive pressure state. Specifically, the ink is introduced (initial introduction of ink) into the negative pressure forming portion 86 in a state where the ink is not filled, and the ink is supplied to the head 3 after the negative pressure forming portion 86 is filled with the ink. After the pressure maintenance is performed, the ink in the negative pressure forming portion 86 is discharged to make the inside into a negative pressure state.

Further, when the pressure in the negative pressure forming unit 86 detected by the pressure sensor 866 is lower than a second predetermined value lower than the first predetermined value, the control unit 9 closes the second on-off valve 882, By sending the ink by the second liquid feed pump 836, the ink is sent from the sub tank 82 to the negative pressure forming unit 86 via the second ink flow path 823, and the pressure in the negative pressure forming unit 86 is adjusted. .
Such control is performed when the pressure in the negative pressure forming unit 86 is lower than the second predetermined value, for example, in a high negative pressure state. Specifically, during printing, the ink in the negative pressure forming portion 86 is sequentially sent to the head 3 and the pressure in the negative pressure forming portion 86 gradually decreases. Therefore, the negative pressure forming portion 86 is printed during printing. This is performed when the internal pressure is too low, and the like, and the ink is supplied into the negative pressure forming unit 86 to bring the inside into a negative pressure state higher than a predetermined pressure.

In the ink supply device 8 and the inkjet recording device 1 configured as described above, an example of the negative pressure forming process performed by the control unit 9 will be described below with reference to FIGS. 4 and 5.
FIG. 4 shows an example of a negative pressure forming process performed to bring the inside of the negative pressure forming unit 86 in a positive pressure state or an atmospheric pressure state into a predetermined negative pressure state after the initial introduction of ink or after pressure maintenance. It is a flowchart shown. FIG. 5 is a flowchart showing an example of a negative pressure forming process performed to bring the pressure in the negative pressure forming unit 86, which fluctuates due to ink ejection, into a negative pressure state within a predetermined pressure range during printing operation.

  First, an example of the negative pressure forming process performed after the initial introduction of ink and the pressure maintenance will be described with reference to FIG. Note that while the negative pressure forming process shown in FIG. 4 is being performed, the printing operation by the head 3 is not performed.

First, based on the result detected by the pressure sensor 866, the control unit 9 determines whether the pressure in the negative pressure forming unit 86 is higher than a first predetermined value (step S101). Here, the first predetermined value is a pressure value in the negative pressure forming portion 86 such that the inside of the head 3 forms a desired negative pressure state.
If it is determined that the pressure in negative pressure forming unit 86 is less than or equal to the first predetermined value (step S101; NO), the inside of negative pressure forming unit 86 is already in a predetermined negative pressure state, and thus the control unit 9 ends the negative pressure formation process.

  On the other hand, when it is determined that the pressure in negative pressure forming unit 86 is higher than the first predetermined value (step S101; YES), control unit 9 closes first on-off valve 812 and third on-off valve 835. , The second on-off valve 882 is opened (step S102). Thereby, the sub tank 82 and the negative pressure forming portion 86 are connected via the third ink flow path 881. Further, by closing the third on-off valve 835, the inflow of ink from the third on-off valve 835 side to the third ink flow path 881 at the junction of the second ink flow path 823 and the third ink flow path 881 Therefore, the ink can efficiently flow from the negative pressure forming portion 86 side to the third ink flow path 881.

  Next, the controller 9 starts the feeding of the ink by the first delivery pump 814 (step S103). Since the first on-off valve 812 is closed in step S102, the ink in the main tank 81 is not supplied to the sub tank 82, and the ink in the negative pressure forming unit 86 is sub tank 82 via the third ink flow path 881. Supplied to Thus, the ink in the negative pressure forming portion 86 can be recovered, and the pressure in the negative pressure forming portion 86 can be reduced.

  Next, the control unit 9 determines whether the pressure in the negative pressure forming unit 86 is less than or equal to a first predetermined value (step S104). If it is determined that the pressure in negative pressure formation unit 86 is higher than the first predetermined value (step S104; NO), control unit 9 performs the process of step S104 again. That is, the control unit 9 continues the liquid feeding of the ink by the first liquid sending pump 814 until the pressure in the negative pressure forming unit 86 becomes lower than or equal to the first predetermined value, and the pressure in the negative pressure forming unit 86 is reduced. Let

  When it is determined that the pressure in the negative pressure forming unit 86 is less than or equal to the first predetermined value (step S104; YES), the control unit 9 stops the ink supply by the first liquid supply pump 814 (step S105). At this time, the control unit 9 switches the three-way switching valve 848 to release the connection between the sub tank 82 and the negative pressure forming unit 86 on the second ink flow passage 823. Thus, the inside of the negative pressure forming portion 86 can be maintained at a desired negative pressure.

Finally, the controller 9 closes the second on-off valve 882 and opens the third on-off valve 835 (step S106) to allow the ink in the sub tank 82 to be fed to the negative pressure forming unit 86. .
In this way, negative pressure formation processing is performed.

Subsequently, an example of the negative pressure forming process performed during the printing operation will be described with reference to FIG.
It is assumed that the printing operation by the head 3 is being performed in parallel while the negative pressure forming process shown in FIG. 5 is being performed.
Further, since steps S201 to S206 of the negative pressure forming process shown in FIG. 5 are the same as steps S101 to S106 of the negative pressure forming process shown in FIG. 4 described above, the description of the overlapping portions will be omitted. .

First, in step S201, the control unit 9 determines whether the pressure in the negative pressure forming unit 86 is higher than a first predetermined value (step S201). Here, the first predetermined value is a pressure value in the negative pressure forming portion 86 to the extent that the inside of the head 3 forms a desired negative pressure state, and is the upper limit value thereof.
If it is determined that the pressure in negative pressure forming unit 86 is equal to or less than the first predetermined value (step S201; NO), control unit 9 performs the process of step S207 described later.

In addition, after closing the second on-off valve 882 and opening the third on-off valve 835 in step S206, the control unit 9 controls the pressure in the negative pressure forming unit 86 based on the result detected by the pressure sensor 866. It is determined whether it is lower than the second predetermined value (step S207). Here, the second predetermined value is a pressure value in the negative pressure forming portion 86 that causes the inside of the head 3 to form a desired negative pressure state, and is a lower limit value thereof.
If it is determined that the pressure in negative pressure forming unit 86 is equal to or higher than the second predetermined value (step S207; NO), control unit 9 performs the process of step S211 described later.

  On the other hand, when it is determined that the pressure in the negative pressure forming unit 86 is lower than the second predetermined value (step S207; YES), the control unit 9 starts the feeding of the ink by the second delivery pump 836 ( Step S208). Since the second on-off valve 882 is closed and the third on-off valve 825 is open in step S206, the ink in the sub tank 82 is transferred via the second ink flow path 823 by the liquid transfer operation of the second liquid transfer pump 836. The liquid is sent to the negative pressure forming unit 86. Thus, the ink can be supplied into the negative pressure forming unit 86, and the pressure in the negative pressure forming unit 86 can be increased.

  Next, the control unit 9 determines whether the pressure in the negative pressure forming unit 86 is equal to or higher than a second predetermined value (step S209). If it is determined that the pressure in negative pressure formation unit 86 is lower than the second predetermined value (step S209; NO), control unit 9 performs the process of step S209 again. That is, the controller 9 continues the liquid feeding of the ink by the second liquid sending pump 836 until the pressure in the negative pressure forming part 86 becomes equal to or higher than the second predetermined value, and the pressure in the negative pressure forming part 86 is increased. Let

  If it is determined that the pressure in the negative pressure forming unit 86 is equal to or higher than the second predetermined value (step S 209: YES), the control unit 9 stops the ink supply by the second liquid supply pump 836 (step S210). At this time, the control unit 9 switches the three-way switching valve 848 to release the connection between the sub tank 82 and the negative pressure forming unit 86 on the second ink flow passage 823. Thus, the inside of the negative pressure forming portion 86 can be maintained at a desired negative pressure.

Finally, the control unit 9 determines whether the printing operation by the head 3 is completed (step S211). If it is determined that the printing operation has not ended (step S211; NO), the control unit 9 performs the process of step S201 again. That is, the control unit 9 repeatedly performs the processes of steps S201 to S211 until the printing operation is completed.
On the other hand, when it is determined that the printing operation has ended (step S211; YES), the control unit 9 ends the negative pressure formation processing.
In this way, negative pressure formation processing is performed.

  As described above, according to the above-described embodiment, the ink supply device 8 communicates the main tank 81 storing ink, the sub tank 82 storing ink supplied from the main tank 81, and the main tank 81 and the sub tank 82. The first ink flow path 811, a first liquid transfer pump 814 provided in the first ink flow path 811 to transfer the ink in the main tank 81 to the sub tank 82, and the main tank 81 and the first liquid flow path 811 in the first ink flow path 811 1) a first on-off valve 812 provided between the liquid supply pump 814 and opening and closing the first ink flow path 811; and the ink supplied from the sub tank 82 is stored and supplied to the head 3 to adjust the internal pressure A negative pressure forming portion 86 for making the head 3 in a negative pressure state, a pressure sensor 866 for detecting the pressure in the negative pressure forming portion 86, a sub tank 82 and a negative pressure type A second ink flow path 823 communicating with the portion 86, a second liquid transfer pump 836 provided in the second ink flow path 823 and transferring the ink in the sub tank 82 to the negative pressure forming portion 86, and a second ink flow A third ink flow path communicating between the second liquid transfer pump 836 and the negative pressure forming portion 86 in the path 823 and the first on-off valve 812 and the first liquid transfer pump 814 in the first ink flow path 811 881, a second on-off valve 882 provided in the third ink flow path 881 to open and close the third ink flow path 881, and the pressure in the negative pressure forming unit 86 detected by the pressure sensor The control unit 9 controls the pressure in the negative pressure forming unit 86 by driving and controlling the liquid pump 814, the first on-off valve 812, the second liquid transfer pump 836, and the second on-off valve 882. In the tank 81 The using the first liquid sending pump 814 for feeding to the sub-tank 82, and discharges the ink of the negative pressure generating unit 86 can adjust the pressure in the negative pressure forming unit 86. Therefore, it is not necessary to provide a bidirectional pump or a plurality of liquid feed pumps in order to discharge the ink in the negative pressure forming unit 86, and the pressure in the negative pressure forming unit can be adjusted with a simple ink flow path configuration. The increase in size and cost of the device can be suppressed.

  Further, when the pressure in the negative pressure forming unit 86 detected by the pressure sensor 866 is higher than the first predetermined value, the control unit 9 closes the first on-off valve 812 and opens the second on-off valve 882 Then, the ink is fed by the first feed pump 814 to send the ink from the negative pressure forming unit 86 to the sub tank 82 via the third ink flow path 881 so that the pressure in the negative pressure forming unit 86 is reduced. Since the adjustment is performed, even if the pressure in the negative pressure forming unit 86 becomes higher than a predetermined value after the initial introduction of ink or after the pressure maintenance, the inside of the negative pressure forming unit 86 can be brought into a predetermined negative pressure state. Further, even if the pressure in the negative pressure forming unit 86 becomes higher than the predetermined value during the printing operation, the inside of the negative pressure forming unit 86 can be returned to the predetermined negative pressure state.

  Further, the control unit 9 closes the second on-off valve 882 when the pressure in the negative pressure forming unit 86 detected by the pressure sensor 866 is lower than a second predetermined value lower than the first predetermined value. The ink is fed by the second feed pump 836 to send the ink from the sub tank 82 to the negative pressure forming unit 86 via the second ink flow path 823 to adjust the pressure in the negative pressure forming unit 86. Therefore, even if the ink in the negative pressure forming unit 86 is ejected from the head 3 during the printing operation and the pressure in the negative pressure forming unit 86 becomes too low, the negative pressure forming unit 86 is not negatively charged. It can be returned to the pressure state.

  Further, since the third on-off valve 835 provided between the sub tank 82 and the second liquid supply pump 836 in the second ink flow path 823 and opening and closing the second ink flow path 823 is further provided. By setting the closed state, the ink is drawn into the third ink flow path 881 only from the negative pressure forming portion 86 at the junction of the second ink flow path 823 and the third ink flow path 881, and the negative pressure formation The ink in the portion 86 can be efficiently recovered.

  Also, the negative pressure forming portion 86 includes a container main body 861 having an opening formed therein and storing ink, a flexible film member 862 covering the opening, and a film member 862 from the inside of the container main body 861 to the outside. Since the spring member 863 for biasing is provided, the negative pressure forming portion 86 can be configured simply, and the apparatus cost can be further suppressed.

  The description in the embodiment of the present invention is an example of the ink supply device and the inkjet recording device according to the present invention, and the present invention is not limited to this. The detailed configuration and the detailed operation of each functional unit constituting the ink supply apparatus and the inkjet recording apparatus can be appropriately changed. Further, the ink supply device and the inkjet recording device of the present invention are not only used for printing on a recording medium, but also for other uses such as forming a wiring pattern by discharging a wiring material to a substrate. It is also possible to use.

  In the embodiment described above, the third on-off valve 835 is provided in the second ink flow path 823, but the third on-off valve 835 may not be provided.

  In the embodiment described above, the negative pressure forming portion 86 is configured to include the container main body 861, the film member 862, and the spring member 863. However, the present invention is not limited to this. The negative pressure forming unit 86 may be configured to be capable of storing ink and capable of reducing the internal pressure by discharging the ink.

  In the embodiment described above, the degassing module 831 is provided in the second ink flow path 823. However, the degassing module 831 may not be provided.

  The present invention can be used for an ink supply device and an inkjet recording device.

1 Ink jet recording apparatus 3 head (ink jet head)
8 Ink Supply Device 81 Main Tank (First Ink Tank)
9 control unit 82 sub tank (second ink tank)
86 Negative Pressure Forming Unit 811 First Ink Flow Path 812 First On-off Valve 814 First Liquid Delivery Pump 823 Second Ink Flow Path 831 Degassing Module 835 Third On-off Valve 836 Second Liquid Delivery Pump 861 Container Body 862 Film Member 863 Spring member (elastic member)
866 Pressure sensor (pressure detector)
881 third ink flow path 882 second on-off valve

Claims (7)

An ink supply apparatus for supplying ink to an ink jet head, comprising:
A first ink tank for storing ink;
A second ink tank for storing ink supplied from the first ink tank;
A first ink flow path communicating the first ink tank and the second ink tank;
A first liquid transfer pump provided in the first ink flow path to transfer the ink in the first ink tank to the second ink tank;
A first on-off valve provided between the first ink tank and the first liquid supply pump in the first ink flow path and opening and closing the first ink flow path;
A negative pressure forming unit that stores ink supplied from the second ink tank and supplies the ink to the ink jet head, and adjusting the internal pressure to make the inside of the ink jet head negative pressure state;
A pressure detection unit that detects the pressure in the negative pressure formation unit;
A second ink flow path communicating the second ink tank and the negative pressure forming portion;
A second liquid transfer pump provided in the second ink flow path to transfer the ink in the second ink tank to the negative pressure forming portion;
Communication is made between the second liquid transfer pump and the negative pressure forming portion in the second ink flow path, and between the first on-off valve and the first liquid transfer pump in the first ink flow path. The third ink flow path,
A second on-off valve provided in the third ink flow path to open and close the third ink flow path;
Driving control of the first liquid transfer pump, the first on-off valve, the second liquid transfer pump, and the second on-off valve based on the pressure in the negative pressure forming unit detected by the pressure detection unit And a control unit for adjusting the pressure in the negative pressure forming unit.   The control unit closes the first on-off valve and opens the second on-off valve when the pressure in the negative pressure forming unit detected by the pressure detection unit is higher than a first predetermined value, By feeding the ink by the first feed pump, the negative pressure forming unit sends the ink to the second ink tank via the third ink flow path, and the pressure in the negative pressure forming unit is determined. The ink supply device according to claim 1, wherein the adjustment is performed.   The control unit closes the second on-off valve when the pressure in the negative pressure forming unit detected by the pressure detection unit is lower than a second predetermined value lower than the first predetermined value, By feeding the ink by the second feed pump, the ink is sent from the second ink tank to the negative pressure forming unit via the second ink flow path, and the pressure in the negative pressure forming unit is The ink supply device according to claim 2, wherein the adjustment is performed.   3. The apparatus according to claim 1, further comprising: a third on-off valve provided between the second ink tank and the second liquid supply pump in the second ink flow path and opening and closing the second ink flow path. 3. The ink supply device according to any one of 3. to 3.   The negative pressure forming portion biases the film member from the inside to the outside of the container body, the container body having an opening formed therein and storing the ink, the flexible film member covering the opening, and The ink supply device according to any one of claims 1 to 4, further comprising an elastic member.   The ink according to any one of claims 1 to 5, further comprising a degassing module provided between the second ink tank and the second liquid supply pump in the second ink flow path. Supply device. The ink supply device according to any one of claims 1 to 6,
An ink jet recording apparatus comprising an ink jet head for discharging the ink supplied by the ink supply apparatus.

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