JP4613987B2 - Liquid supply device, liquid discharge device, and control method of liquid discharge device - Google Patents

Description

  The present invention relates to a liquid supply apparatus, a liquid discharge apparatus, and a control method for the liquid discharge apparatus for supplying a liquid to a liquid consumption target (a liquid discharge head that discharges ink). More specifically, the present invention relates to a technology that can easily supply liquid to a consumption target and discharge (circulate) the liquid from the consumption target.

  Conventionally, as an example of a liquid ejecting apparatus that ejects (consumes) liquid, an image is formed by supplying ink (liquid) to a liquid ejecting head and ejecting ink from a nozzle of the liquid ejecting head toward a recording sheet. An ink jet printer configured to do this is known. In such an ink jet printer, ink is stably supplied from the ink cartridge (liquid tank) in which ink is stored to the liquid ejection head in order to ensure the stability of ink ejection. Is required.

  Here, recent inkjet printers tend to increase the number of nozzles in order to achieve high speed. In particular, the line head type inkjet printer has a large number of nozzles arranged in accordance with the paper width of the maximum size of recording paper that can be printed, so compared to the serial head type that performs printing by moving in the paper width direction, The number of nozzles is very large. For this reason, since the amount of ink consumed per unit time increases, it is important not to cut the ink in the middle of printing. Even in the case of a serial head type ink jet printer, the amount of ink consumed increases when large format printing is performed.

Therefore, a technique is known in which ink is temporarily stored in a sub-tank (auxiliary tank) before being supplied to the liquid ejection head, and the ink in the sub-tank is consumed while the sub-tank is replenished with ink at the same time. Specifically, a sufficient ink holding volume of the sub tank is ensured, and ink is replenished from the large capacity ink cartridge to the sub tank by a transfer pump (see, for example, Patent Document 1).
JP 2008-132762 A

  In addition, in a line head type ink jet printer, heat generated due to an increase in the size of the liquid discharge head and the overall volume of the ink flow path may be large, and air bubbles such as air are likely to be mixed into the ink in the flow path. ing. When bubbles are accumulated in the liquid ejection head, the flow path is blocked, and the flow of ink to the nozzles is obstructed, causing insufficient supply of ink during printing. Furthermore, if there are bubbles in the ink, the bubbles act like a damper that releases the discharge pressure due to the compressibility of the gas, weakening the ink discharge force or causing disturbance in the ink discharge direction. Furthermore, when bubbles in the ink expand due to an installation environment of the ink jet printer, a temperature change accompanying ink ejection, a change in atmospheric pressure, or the like, the ink may leak from the nozzles. Even in the case of a serial head type ink jet printer, when it is operated for a long time, bubbles due to heat generation are likely to occur.

Therefore, in order to solve such a problem caused by the presence of bubbles in the ink, various techniques are known in which bubbles included in the ink can be removed. Specifically, the ink is circulated between the liquid discharge head and the sub tank by a transfer pump, and bubbles in the ink are moved to the sub tank to be removed (for example, see Patent Document 2).
JP 2005-246640 A

  However, the technique disclosed in Patent Document 1 does not circulate ink between the liquid discharge head and the sub tank. For this reason, even if the sub tank is provided, the bubbles in the ink in the liquid discharge head cannot be removed. On the other hand, the technique disclosed in Patent Document 2 circulates ink not only between the liquid ejection head and the sub tank but also in the flow path including the ink cartridge, so that the ink flow path is long. In particular, in the case of a color inkjet printer, an ink flow path is required for each ink color (minimum 3 colors, 6 colors or 8 colors if there are many). As a result, the inkjet printer becomes larger and more complicated.

  Therefore, the problem to be solved by the present invention is to enable easy supply of ink (liquid) to the liquid discharge head and discharge (circulation) from the liquid discharge head, and to realize a small apparatus. is there.

The present invention solves the above problems by the following means.
The invention according to claim 1 of the present invention includes a liquid tank storing a liquid to be supplied to a liquid consumption target, a transfer pump for transferring the liquid stored in the liquid tank, and transferred by the transfer pump. A supply pipe that is piped to supply the consumed liquid to the consumption target, a discharge pipe that is piped to discharge liquid that has not been consumed by the consumption target from the consumption target, the liquid tank, and the discharge A three-way valve disposed between a pipe and the transfer pump and capable of switching between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump; and transfer by the transfer pump An auxiliary tank that temporarily stores the liquid that has been collected before being supplied to the consumption object, and the auxiliary tank that is stored when the liquid stored in the auxiliary tank reaches a certain amount or more. Possess a pipe to the return pipe to return the liquid to the liquid tank from the said three-way valve, when switched into the flow path toward the transfer pump from the liquid tank, the liquid in the liquid tank A liquid transfer path is configured to return to the liquid tank via the three-way valve, the transfer pump, the auxiliary tank, and the return pipe in this order, and the flow from the discharge pipe to the transfer pump is performed by the three-way valve. When switching to a path, the liquid discharged from the consumption target to the discharge pipe returns to the consumption target via the three-way valve, the transfer pump, the auxiliary tank, and the supply pipe in this order. path is a liquid supply apparatus which Ru is configured.

(Function)
In the first aspect of the present invention, a three-way valve is arranged between the liquid tank and the discharge pipe and the transfer pump. The three-way valve can switch between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump. Therefore, in a liquid supply apparatus that supplies liquid to the consumption target, the liquid can be supplied from the liquid tank to the consumption target by opening the three-way valve toward the liquid tank and driving the transfer pump. On the other hand, if the three-way valve is opened to the discharge pipe side and the transfer pump is driven, the liquid can be discharged from the consumption target through the discharge pipe. As a result, the discharged liquid can be supplied again to the consumption object.

According to a second aspect of the present invention, there is provided a liquid discharge head capable of discharging the supplied liquid from the nozzle, a liquid tank storing the liquid discharged by the liquid discharge head, and storing in the liquid tank. A transfer pump for transferring the liquid being supplied, a supply pipe piped to supply the liquid transferred by the transfer pump to a supply port provided in the liquid discharge head, A discharge pipe piped to discharge liquid from a discharge port provided on the opposite side of the supply port; and disposed between the liquid tank, the discharge pipe and the transfer pump, and the transfer from the liquid tank. 3 and way valve capable flow path towards the pump from the discharge pipe switching a flow path towards the transfer pump, provided a liquid that has been transferred by the transfer pump to the liquid ejection head An auxiliary tank for temporarily storing at before, the when the auxiliary tank liquid stored in exceeds a specific amount, and the auxiliary tank return plumbed to return the liquid to the liquid tank from tube have a, wherein a three-way valve, when switched into the flow path toward the transfer pump from the liquid tank, the liquid is the 3-way valve of the liquid tank, the transfer pump, said auxiliary tank, said return pipe When the liquid transfer path returning to the liquid tank via the order is configured and the three-way valve switches to the flow path from the discharge pipe to the transfer pump, the discharge port of the liquid discharge head The liquid discharge path from the supply port to the liquid discharge head passes through the three-way valve, the transfer pump, the auxiliary tank, and the supply pipe in this order. A liquid discharge apparatus that will be.

(Function)
In the invention according to the second aspect, a three-way valve is disposed between the liquid tank and the discharge pipe and the transfer pump. The three-way valve can switch between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump. Therefore, in a liquid discharge apparatus that discharges liquid from the nozzle of the liquid discharge head, if the three-way valve is opened to the liquid tank side and the transfer pump is driven, the liquid can be supplied from the liquid tank to the liquid discharge head through the supply pipe. On the other hand, if the three-way valve is opened to the discharge pipe side and the transfer pump is driven, the liquid can be discharged from the liquid discharge head through the discharge pipe. As a result, even if bubbles are included in the liquid in the liquid discharge head, the bubbles can be discharged out of the liquid discharge head. In order to circulate the discharged liquid and remove the bubbles, for example, the liquid containing the bubbles may be temporarily stored in the auxiliary tank before being supplied to the liquid discharge head.

Furthermore, the invention according to claim 7 of the present invention is directed to a liquid discharge head capable of discharging a supplied liquid from a nozzle, a liquid tank storing liquid discharged by the liquid discharge head, and the liquid tank. A transfer pump for transferring the stored liquid, a supply pipe piped to supply the liquid transferred by the transfer pump to a supply port provided in the liquid discharge head, and in the liquid discharge head The liquid tank is disposed between a discharge pipe provided to discharge the liquid from a discharge port provided on the opposite side of the supply port, the liquid tank, and between the discharge pipe and the transfer pump. A three-way valve capable of switching between a flow path to the transfer pump and a flow path from the discharge pipe to the transfer pump; and to control the drive of the transfer pump and the operation of the three-way valve When the control device, an auxiliary tank for temporarily storing before supplying the liquid that has been transferred by the transfer pump to the liquid discharge head, the liquid reserved in the auxiliary tank reaches or exceeds a certain amount, A return pipe piped to return the liquid from the auxiliary tank to the liquid tank, and the control device switches the three-way valve from the liquid tank to the flow path toward the transfer pump. In the auxiliary tank, a transfer path is configured to drive the transfer pump and to return the liquid to the liquid tank through the three-way valve, the transfer pump, the auxiliary tank, and the return pipe in this order. maintaining the liquid at a constant full state, by the control device, the transfer pump is driven in a state in which the three-way valve is switched to the flow path toward the transfer pump from the discharge pipe, The outlet of the liquid in the serial liquid discharge head, the discharge tube, the three-way valve, the transfer pump, said auxiliary tank, the supply pipe to return the liquid to the liquid discharge head by way of the order of the supply port transfer This is a method for controlling a liquid ejection apparatus that constitutes a path and circulates the liquid in the liquid ejection head .

(Function)
In the invention described in claim 8, a three-way valve is arranged between the liquid tank and the discharge pipe and the transfer pump, and a flow path from the liquid tank to the transfer pump and a flow from the discharge pipe to the transfer pump. The road can be switched. If the transfer pump is driven in a state where the three-way valve is switched from the discharge pipe to the flow path toward the transfer pump, the liquid in the liquid discharge head can be circulated through the discharge pipe, the auxiliary tank, and the supply pipe. Therefore, even if bubbles are included in the liquid in the liquid discharge head, the bubbles can be discharged out of the liquid discharge head. In addition, the liquid containing bubbles is temporarily stored in the auxiliary tank before being supplied to the liquid discharge head. As a result, bubbles in the liquid can be effectively removed.

  According to the liquid supply apparatus according to the first aspect of the present invention, when the three-way valve is opened to the liquid tank side and the transfer pump is driven, the liquid can be supplied from the liquid tank to the consumption object through the supply pipe. On the other hand, if the three-way valve is opened to the discharge pipe side and the transfer pump is driven, the liquid can be discharged from the consumption target through the discharge pipe, so that the discharged liquid can be supplied again to the consumption target. Therefore, in a liquid supply apparatus that supplies liquid to the consumption target, the supply and discharge (circulation) of the liquid can be simplified with only a three-way valve, and the apparatus can be downsized.

  According to the liquid ejecting apparatus of the second aspect of the present invention, if the three-way valve is opened to the liquid tank side and the transfer pump is driven, the liquid can be supplied from the liquid tank to the liquid ejecting head through the supply pipe. On the other hand, if the three-way valve is opened to the discharge pipe side and the transfer pump is driven, liquid can be discharged from the liquid discharge head through the discharge pipe, and even if bubbles are contained in the liquid in the liquid discharge head, the bubbles Can be discharged out of the liquid discharge head. Therefore, in a liquid discharge apparatus that discharges liquid from the nozzles of the liquid discharge head, the supply and discharge (circulation) of the liquid can be simplified with only a three-way valve, and the apparatus can be downsized. Further, for example, if the liquid containing bubbles is temporarily stored in the auxiliary tank before being supplied to the liquid discharge head, the bubbles can be removed from the liquid.

  According to the control method of the liquid discharge apparatus according to the eighth aspect of the present invention, if the transfer pump is driven in a state where the three-way valve is switched from the discharge pipe to the flow path toward the transfer pump, the liquid in the liquid discharge head Can be circulated through the discharge pipe, auxiliary tank, and supply pipe. Therefore, even if bubbles are included in the liquid in the liquid discharge head, the bubbles can be discharged out of the liquid discharge head. Therefore, the supply and discharge (circulation) of the liquid can be simplified with only the three-way valve, and the apparatus can be downsized. Further, since the liquid containing bubbles is temporarily stored in the auxiliary tank before being supplied to the liquid ejection head again, the bubbles are removed from the liquid.

Embodiments of the present invention will be described below with reference to the drawings.
In the following embodiments, four colors of ink (liquid) of Y (yellow), M (magenta), C (cyan), and K (black) are lined as the liquid supply device and the liquid discharge device of the present invention. The color inkjet printer 10 that supplies and discharges to the head 20 (corresponding to the consumption target and the liquid discharge head in the present invention) will be described as an example.

FIG. 1 is a side view illustrating an outline of an inkjet printer 10 according to the present embodiment.
As shown in FIG. 1, the inkjet printer 10 includes paper feed trays 11a, 11b, and 11c that can separately accommodate three types of recording papers 100 having different sizes, and paper feed trays 11a and 11b according to the sizes to be printed. , 11c, a sheet feeding unit 12 that selectively feeds the recording paper 100, a line head 20 that performs printing on the fed recording paper 100, and an ink ejection surface of the line head 20 during non-printing A head cap 22 that covers and protects the paper, a paper discharge unit 13 that discharges the printed recording paper 100, and a paper discharge tray 14 that stores the discharged recording paper 100. The head cap 22 can seal the ink discharge surface of the line head 20 by an opening / closing device (not shown).

  Here, the line head 20 performs printing by ejecting ink onto the recording paper 100 fed so as to face the line head 20. Further, it is possible to print up to the width of the maximum-size recording paper 100 to be fed without moving the head in the width direction of the recording paper 100. Therefore, as compared with a serial head that performs printing by moving the head in the width direction of the recording paper 100, there are advantages in that not only vibration and noise are reduced, but also the printing speed can be remarkably increased.

  Further, the ink jet printer 10 of this embodiment is a “head separate type” in which an ink cartridge 30 (which corresponds to a liquid tank in the present invention) separate from the line head 20 is mounted on the ink jet printer 10. The ink cartridge 30 stores four colors of ink (Y, M, C, K) supplied to the line head 20 for each color, and is detachably attached to the ink jet printer 10. Therefore, when all the ink in the ink cartridge 30 is consumed, it can be quickly replaced with a new one.

  Furthermore, a sub tank 40 (corresponding to an auxiliary tank in the present invention) is disposed between the line head 20 and the ink cartridge 30 (before supplying ink to the line head 20). The sub-tank 40 temporarily stores ink at a position lower than the line head 20 and acts to give a constant negative pressure to the ink in the line head 20 based on the water head difference. Therefore, not only the leakage of the ink from the line head 20 can be prevented, but also a state where ink can be stably ejected can be always maintained.

  Furthermore, a transfer pump 50 for transferring the ink stored in the ink cartridge 30 is disposed between the ink cartridge 30 and the sub tank 40. If the drive of the transfer pump 50 is controlled by a control device (not shown), the ink (Y, M, C, K) in the ink cartridge 30 is supplied to the line head 20 via the sub tank 40.

  In order to perform printing with such an ink jet printer 10, a recording sheet 100 corresponding to the size to be printed is selectively fed from a paper feed tray 11 a, 11 b, or 11 c by a paper feed unit 12. Further, the head cap 22 is pulled away from the line head 20 to expose the ink discharge surface of the line head 20. Then, while moving the recording paper 100, ink of each color is ejected from the line head 20 toward the recording paper 100 to perform color printing. The recording paper 100 on which printing has been performed is discharged by the paper discharge unit 13 and then stocked on the paper discharge tray 14.

FIG. 2 is a perspective view showing a printing portion of the inkjet printer 10 of the present embodiment.
As shown in FIG. 2, the inkjet printer 10 includes a plurality (four) of line heads 20, ink cartridges 30, sub tanks 40, and the like according to the types of ink to be ejected (Y, M, C, and K colors). A transfer pump 50 is provided. Further, a plurality of (four) return pipes 86 piped so as to return each ink from each sub tank 40 to each ink cartridge 30 and each ink transferred by each transfer pump 50 are supplied to each line head 20. A plurality of (four) supply pipes 87, and a plurality of (four) discharge pipes 88 piped to discharge each ink that has not been consumed by each line head 20 from each line head 20. Have. Furthermore, a plurality of (four) three-way valves 60 capable of switching between a flow path from each ink cartridge 30 to each transfer pump 50 and a flow path from each discharge pipe 88 to each transfer pump 50, And a plurality (four) of check valve arrays 70 capable of changing the transfer path.

  Here, each line head 20 has a length corresponding to the width of the recording paper 100, and ejects ink of four colors Y, M, C, and K for each line head 20. Each line head 20 is supplied with ink of each color from an ink cartridge 30 in which four colors of Y, M, C, and K are separately stored. Specifically, each ink cartridge 30 is detachably mounted on a detachable base 15 to which four (each ink color) transfer pipes 81 are connected. Each transfer pipe 81 is connected to one inlet side of each three-way valve 60.

  Further, since the transfer pipes 82 are connected to the outlet sides of the respective three-way valves 60, the respective inks of the respective ink cartridges 30 are supplied with the respective check valve arrays 70, the respective transfer pumps 50, and the respective transfer pipes 85. And then transferred to each sub tank 40. Furthermore, each ink that is transferred to each sub tank 40 and temporarily stored is supplied to each line head 20 via each supply pipe 87. When each ink stored in each sub-tank 40 exceeds a certain amount, it is returned to each ink cartridge 30 by each return pipe 86 connected to the detachable base 15.

  As described above, the ink jet printer 10 according to this embodiment includes the ink cartridge 30, the transfer pipe 81, the three-way valve 60, the transfer pipe 82, and the check according to the color (Y, M, C, K) of the ejected ink. A valve array 70, a transfer pump 50, a transfer pipe 85, a sub tank 40, a supply pipe 87, a line head 20, a return pipe 86, and the like are provided. Then, the ink in the ink cartridge 30 is supplied to the line head 20 via the sub tank 40 by the transfer pump 50 and is discharged toward the recording paper 100.

  Ink that has not been ejected from the line head 20 is returned to the sub tank 40 by the transfer pump 50 via the discharge pipe 88. Specifically, since the discharge pipe 88 is connected to the other inlet side of the three-way valve 60, when the ink is supplied to the line head 20 by the three-way valve 60, the transfer pump 50 is supplied from the ink cartridge 30. When the ink is discharged from the line head 20, the flow path is switched from the discharge pipe 88 to the transfer pump 50. Therefore, the ink jet printer 10 according to the present embodiment can not only supply ink from the ink cartridge 30 to the line head 20, but also discharge ink from the line head 20 and circulate the ink through the sub tank 40. Bubbles contained can be removed.

FIG. 3 is a conceptual diagram illustrating a piping system for one color of the printing unit in the inkjet printer 10 of the present embodiment.
As shown in FIG. 3, the inkjet printer 10 includes a line head 20, an ink cartridge 30, a sub tank 40, a transfer pump 50, a three-way valve 60, and a check valve array 70. These are provided for each of the four color inks (Y, M, C, K). However, the transfer pumps 50 are simultaneously driven by a common drive motor 51 (corresponding to a drive source in the present invention). Specifically, each transfer pump 50 is a tube pump, and ink can be transferred by elastically deforming the elastic tube of each transfer pump 50 continuously by one drive motor 51. In addition, each three-way valve 60 can be switched by one common operating source (not shown). Therefore, a small and inexpensive inkjet printer 10 can be realized.

  Further, the ink cartridge 30 and the three-way valve 60 are connected by a transfer pipe 81 via the detachable base 15. Furthermore, the three-way valve 60 and the check valve array 70 are connected by a transfer pipe 82, and the check valve array 70 and the transfer pump 50 are connected by a transfer pipe 83 and a transfer pipe 84. Yes. Further, the check valve array 70 and the sub tank 40 are connected by a transfer pipe 85 having a filter 91. Therefore, if the transfer pump 50 is driven by the drive motor 51, the ink in the ink cartridge 30 can be transferred to the sub tank 40.

  The sub tank 40 is connected to the ink cartridge 30 via the return pipe 86 and the detachable base 15, and is connected to the supply port 20 a of the line head 20 by a supply pipe 87 having a filter 92. Therefore, the transfer pump 50 can return the ink in the sub tank 40 to the ink cartridge 30, or the ink can be supplied to the line head 20 and discharged from the nozzle 21. The sub tank 40 has an air release valve 41 for opening the inside to the atmosphere. The ink leaking through the air release valve 41 is stored in the waste ink reservoir 42.

  A discharge port 20 b is provided on the opposite side of the line head 20 from the supply port 20 a, and the discharge port 20 b and the three-way valve 60 are connected by a discharge pipe 88. Therefore, the three-way valve 60 is switched to the line head 20 side, the bubbles contained in the ink in the line head 20 are discharged together with the ink from the discharge port 20b, and circulated between the sub tank 40 and the ink in the ink. Bubbles can be removed from

  Furthermore, the head cap 22 disposed so as to face the line head 20 is connected to the check valve array 70 by a discharge pipe 89 having a filter 93. Therefore, if the ink containing bubbles is sucked from the nozzle 21 of the line head 20 toward the head cap 22, the bubbles near the nozzle 21 can be discharged together with the ink, and the bubbles can be removed by the sub tank 40.

FIG. 4 is a sectional view and a perspective view partially showing the line head 20.
As shown in FIG. 4, the line head 20 is configured by laminating a barrier layer 24 on a semiconductor substrate 23 and bonding a nozzle sheet 25 on which the nozzles 21 are formed to the barrier layer 24. A plurality of heating resistors 26 are deposited on the semiconductor substrate 23 in one direction at regular intervals, and an ink liquid chamber 27 is formed by the semiconductor substrate 23, the barrier layer 24, and the nozzle sheet 25 surrounding the heating resistor 26. Has been.

  A common flow path member 28 is disposed on the upper side of the semiconductor substrate 23, and a common ink flow path 29 formed by the common flow path member 28 communicates with all the ink liquid chambers 27. Therefore, the ink in the sub tank 40 (see FIG. 3) is supplied to all the ink liquid chambers 27 through the ink flow path 29. When a pulse current is passed through the heating resistor 26 for a short time (for example, between 1 to 3 μsec), the heating resistor 26 is rapidly heated. As a result, an ink bubble is generated at a portion in contact with the heating resistor 26, and a predetermined volume of ink is pushed away by the expansion of the bubble (the ink boils). As a result, ink having a volume equivalent to the pushed ink is ejected from the nozzle 21 as ink droplets.

  As described above, the line head 20 generates bubbles by heat and ejects ink, so that bubbles (see FIG. 4B) are likely to be mixed in the ink. Further, when ink is initially supplied, the air present in the ink flow path 29 of the line head 20 mixes the ink and air, and bubbles are mixed into the ink. If there are bubbles in the ink in the ink chamber 27, the ink ejection force is weakened by the compressibility of the gas, and the ink ejection direction is disturbed. Further, when bubbles in the ink expand due to a temperature change accompanying ink ejection (heating of the heating resistor 26), the ink in the ink liquid chamber 27 may leak from the nozzle 21 without permission.

  Therefore, as shown in FIG. 3, the ink jet printer 10 of the present embodiment removes relatively large bubbles contained in the ink in the line head 20 by circulating the ink in the line head 20 through the discharge pipe 88. To do. Further, by sucking ink from the nozzle 21 toward the head cap 22, relatively small bubbles in the vicinity of the nozzle 21 are discharged together with the ink and circulated through the discharge pipe 89 to remove the bubbles. The circulation of ink through the discharge pipe 88, the three-way valve 60 and the transfer pipe 82 and the circulation through the discharge pipe 89 are switched by the check valve array 70.

FIG. 5 is a cross-sectional view showing the check valve array 70 in the inkjet printer 10 (see FIG. 3) of the present embodiment, and shows a state in which the ink in the line head 20 (see FIG. 3) is circulated.
FIG. 6 is a cross-sectional view showing the check valve array 70 in the inkjet printer 10 of this embodiment, and shows a state in which the ink sucked into the head cap 22 (see FIG. 3) is circulated.

  As shown in FIGS. 5 and 6, the check valve array 70 serves as an ink inlet, a first inlet 71 connected to the transfer pipe 82, and another ink inlet connected to the discharge pipe 89. A second inlet 72. Further, a first outlet 73 connected to a transfer pipe 85 serving as an ink outlet and connected to the sub tank 40 (see FIG. 3) is provided. Furthermore, a pump connection port 74 connected to the transfer pipe 83 connected to the transfer pump 50 (see FIG. 3) and a pump connection port 75 connected to the transfer pipe 84 connected to the transfer pump 50 are provided.

  Such a check valve array 70 includes four check valves 76a, 76b, 76c, and 76d. Each check valve 76a, 76b, 76c, 76d passes ink in one direction, and the flow in the reverse direction is stopped by resistance. Therefore, in FIGS. 5 and 6, the check valve 76a and the check valve 76b pass ink only in the direction from the top to the bottom, and the check valve 76c and the check valve 76d are in the direction from the bottom to the top. Only get ink through.

  Here, when the drive motor 51 shown in FIG. 3 is rotated in the CW direction (clockwise), the elastic tube in the transfer pump 50 is continuously elastically deformed in the CW direction. Therefore, the ink in the transfer tube 83 is transferred as indicated by the upward arrow shown in FIG. 5, and the ink in the transfer tube 84 is transferred as indicated by the downward arrow shown in FIG. In the present embodiment, the ink transfer in the CW direction by the transfer pump 50 is the forward direction.

  Accordingly, the ink is sucked out from the pump connection port 74 and is directed to the pump connection port 74 through the transfer pipe 82, the first inlet 71, and the check valve 76b depending on the directions of the check valve 76b and the check valve 76c. A transfer path is formed. Further, ink is pushed into the pump connection port 75, and the transfer toward the transfer pipe 85 through the pump connection port 75, the check valve 76 d, and the first outlet 73 depending on the directions of the check valve 76 a and the check valve 76 d. A path is formed.

  On the other hand, when the drive motor 51 shown in FIG. 3 is rotated in the CCW direction (counterclockwise), the elastic tube in the transfer pump 50 is continuously elastically deformed in the CCW direction. Therefore, the ink in the transfer tube 83 is transferred as indicated by the downward arrow shown in FIG. 6, and the ink in the transfer tube 84 is transferred as indicated by the upward arrow shown in FIG. In the present embodiment, the ink transfer in the CCW direction by the transfer pump 50 is the reverse forward direction.

  Therefore, the ink is sucked out from the pump connection port 75, and is directed to the pump connection port 75 through the discharge pipe 89, the second inlet 72, and the check valve 76a depending on the directions of the check valve 76a and the check valve 76d. A transfer path is formed. Further, the ink is pushed into the pump connection port 74, and the transfer toward the transfer pipe 85 through the pump connection port 74, the check valve 76c, and the first outlet 73 depending on the direction of the check valve 76b and the check valve 76c. A path is formed.

  As described above, the check valve array 70 can be switched to another inlet (the first inlet 71 or the second inlet 72) only by switching whether the ink is transferred in the CW direction or the CCW direction by one transfer pump 50. To the same outlet (first outlet 73). Specifically, the check valve array 70 is configured such that when the ink is transferred in the forward direction by the transfer pump 50, the ink enters the first inlet 71 from the transfer pipe 82 connected to the line head 20 (see FIG. 3). The ink transfer path is changed so that the ink is transferred from the first outlet 73 toward the transfer pipe 85 connected to the sub tank 40 (see FIG. 3). Thereby, the ink in the line head 20 can be circulated through the sub tank 40.

  Conversely, when the ink is transferred in the reverse direction by the transfer pump 50, the check valve array 70 receives the ink from the discharge pipe 89 connected to the head cap 22 (see FIG. 3) and enters the second inlet 72. The ink transfer path is changed so that the ink is transferred from the outlet 73 toward the transfer pipe 85 connected to the sub tank 40 (see FIG. 3). Thereby, the ink sucked by the head cap 22 can be circulated through the sub tank 40.

  The transfer pipe 82 is also connected to the ink cartridge 30 (see FIG. 3) by switching the three-way valve 60 (see FIG. 3). Therefore, if the ink is transferred in the forward direction by the transfer pump 50, the ink stored in the ink cartridge 30 enters the first inlet 71, exits from the first outlet 73, and is transferred toward the transfer pipe 85. Thus, the ink transfer path can be changed. Thereby, the ink in the ink cartridge 30 can be filled in the sub tank 40 (see FIG. 3). The sub tank 40 is filled with ink when the ink jet printer 10 (see FIG. 3) is used or when the sub tank 40 is refilled with ink.

FIG. 7 is a flowchart showing a flow of ink filling into the sub tank 40 in the inkjet printer 10 (see FIG. 3) of the present embodiment.
FIG. 8 is a conceptual diagram showing a piping system for one color of the printing section in the ink jet printer 10 of the present embodiment, and shows a state in the middle of filling the sub tank 40 with ink.
Furthermore, FIG. 9 is a conceptual diagram showing a piping system for one color of the printing portion in the ink jet printer 10 of the present embodiment, and shows a state at the end of ink filling into the sub tank 40.

  When the ink filling into the sub tank 40 is started in step S1 shown in FIG. 7, it is detected in the next step S2 whether or not the ink cartridge 30 side of the three-way valve 60 is “open”. If it is not “open”, the process branches to step S3, and the ink cartridge 30 side is switched to “open”. The three-way valve 60 shown in FIGS. 8 and 9 shows a state in which the ink cartridge 30 side is “open”.

  If the ink cartridge 30 side of the three-way valve 60 is “open”, the process proceeds to step S4, and it is detected whether or not the air release valve 41 of the sub tank 40 is “open”. If it is not “open”, the process branches to step S5, and the atmosphere release valve 41 is switched to “open”. In addition, the air release valve 41 shown in FIG.8 and FIG.9 has shown the state open.

  Thus, after the ink cartridge 30 side of the three-way valve 60 is set to “open” and the atmosphere release valve 41 is set to “open”, the transfer pump 50 is rotationally driven in the CW direction (clockwise) in step S6. . 8 and 9 shows a state in which the transfer pump 50 is rotationally driven in the CW direction (clockwise) by a drive motor 51 controlled by a control device (not shown).

  When the transfer pump 50 is rotationally driven in the CW direction (clockwise), the ink is transferred in the forward direction (CW direction) as indicated by an arrow in the transfer pump 50 shown in FIG. As a result, the ink stored in the ink cartridge 30 mounted on the detachable base 15 is transferred to the transfer pipe 81, the three-way valve 60, the transfer pipe 82, the check valve array 70, the transfer, as shown by the arrows in FIG. The pipe 83, the transfer pump 50, the transfer pipe 84, the check valve array 70, the transfer pipe 85, and the filter 91 are transferred to the sub tank 40 and stored. If foreign matter or the like is mixed in the transferred ink, it is removed by the filter 91 before being stored in the sub tank 40.

  When the transferred ink is stored in the sub tank 40, the liquid level of the ink in the sub tank 40 gradually increases. On the other hand, in the ink cartridge 30, the internal pressure decreases as the ink is transferred. Therefore, the air in the sub tank 40 is sucked into the ink cartridge 30 through the return pipe 86. Since the air release valve 41 is opened, the internal pressure of the ink cartridge 30 is maintained at the same internal pressure (atmospheric pressure) as that of the sub tank 40.

  When the ink level in the sub tank 40 reaches the inlet of the return pipe 86, the return pipe 86 is plugged with ink as shown in FIG. As a result, the ink cartridge 30 cannot suck air from the return pipe 86, but this time, the ink in the sub tank 40 is sucked. In this state, even if the transfer of the ink in the forward direction by the transfer pump 50 is continued, the same amount of ink as the ink transferred from the ink cartridge 30 to the sub tank 40 is returned to the return pipe 86 as shown by the arrows in FIG. Thus, the ink is returned from the sub tank 40 to the ink cartridge 30. Therefore, the ink in the sub tank 40 is kept constant in a full state (the state of the liquid level shown in FIG. 9). The ink leaking through the “open” atmosphere release valve 41 is stored in the waste ink reservoir 42.

  Here, during the drive time t1 of the transfer pump 50 (drive motor 51), the empty sub tank 40 is filled with the ink of the ink cartridge 30, and the return pipe 86 returns the ink from the sub tank 40 to the ink cartridge 30. It is enough time. Then, in step S7 shown in FIG. 7, it is detected whether or not the driving time is greater than or equal to t1, and if the driving time is greater than or equal to t1, the process proceeds to the next step S8 to stop the rotational driving of the transfer pump 50. As a result, the ink in the sub tank 40 can be surely filled (the liquid level shown in FIG. 9), and the ink filling in step S9 is completed.

  When the sub tank 40 is filled with ink in this way, the ink filling is completed as shown in FIG. 9, but no ink is supplied into the line head 20 when the ink jet printer 10 is used. Therefore, this time, the ink stored in the sub tank 40 is supplied to the line head 20.

FIG. 10 is a flowchart showing the flow of ink supply to the line head 20 in the inkjet printer 10 (see FIG. 3) of the present embodiment.
FIG. 11 is a conceptual diagram showing a piping system for one color of the printing section in the ink jet printer 10 of the present embodiment, and shows a state in the middle of ink supply to the line head 20.
Furthermore, FIG. 12 is a conceptual diagram showing a piping system for one color of the printing unit in the ink jet printer 10 of the present embodiment, and shows a state at the end of the ink supply to the line head 20.

  When the ink supply to the line head 20 is started in step S11 shown in FIG. 10, it is detected in the next step S12 whether or not the line head 20 side of the three-way valve 60 is “open”. If it is not “open”, the process branches to step S13 to switch the line head 20 side to “open”. The three-way valve 60 shown in FIGS. 11 and 12 shows a state in which the line head 20 side is “open”.

  If the line head 20 side of the three-way valve 60 is “open”, the process proceeds to step S14, and whether or not the atmosphere release valve 41 of the sub tank 40 (see FIGS. 11 and 12) is “closed”. Is detected. If it is not “closed”, the process branches to step S15, and the atmosphere release valve 41 is switched to “closed”. Note that the atmosphere release valve 41 shown in FIGS. 11 and 12 is in a “closed” state.

  Thus, after the line head 20 side of the three-way valve 60 is set to “open” and the atmosphere release valve 41 is set to “close”, the transfer pump 50 is rotationally driven in the CW direction (clockwise) in step S16. . 11 and 12 shows a state where the transfer pump 50 is rotationally driven in the CW direction (clockwise) by a drive motor 51 controlled by a control device (not shown).

  When the transfer pump 50 is rotationally driven in the CW direction (clockwise), air is transferred in the forward direction (CW direction) as indicated by an arrow in the transfer pump 50 shown in FIG. Thus, the air in the line head 20 is transferred from the nozzle 21 while entraining the air, and the discharge pipe 88, the three-way valve 60, the transfer pipe 82, the check valve array 70, the transfer pipe as shown by the arrows in FIG. 83, the transfer pump 50, the transfer pipe 84, the check valve array 70, the transfer pipe 85, and the filter 91 are transferred to the sub tank 40. Then, since the inside of the sub tank 40 is pressurized by the transferred air, the ink is pushed out to the supply pipe 87 connected below the sub tank 40.

  The ink pushed out to the supply pipe 87 is supplied to the line head 20 from the supply port 20 a through the filter 92. As a result, the inside of the line head 20 is filled with ink, and the nozzles 21 are blocked with ink. Even if the transfer of the ink by the transfer pump 50 is continued in this state, air is not caught from the nozzle 21 and the ink is continuously supplied while the pressure in the line head 20 remains constant. As a result, the air in the line head 20 is pushed out by the ink, and the pushed-out air is separated from the ink (gas-liquid separation) in the sub tank 40. If foreign matter or the like is mixed in the transferred ink, it is removed by the filter 92 before being supplied to the line head 20.

  Further, in the inkjet printer 10 of the present embodiment, the volume in the sub tank 40 is Vs, and the ink discharge path is the same as the line head 20, the transfer pump 50, the supply pipe 87, the discharge pipe 88, and the discharge pipe 88. Vs ≧ Vh when the total volume in the three-way valve 60, the transfer pipe 82, the check valve array 70, the transfer pipe 83, the transfer pipe 84, and the transfer pipe 85 is Vh. ing. Therefore, once the ink is stored in the sub tank 40, the air in the transfer path can be replaced with the ink in a short time using only the ink in the sub tank 40. When the ink pushed out from the subtank 40 to the supply pipe 87 returns to the subtank 40 again, the ink in the line head 20 circulates through the subtank 40 as shown by the arrows in FIG. As a result, the ink in the sub tank 40 is kept constant in a predetermined state (the state of the liquid level shown in FIG. 12). In addition, all bubbles mixed in the ink during the ink supply process are removed by the sub tank 40.

  Here, during the drive time t2 of the transfer pump 50 (drive motor 51), the ink in the sub tank 40 is supplied to the empty line head 20, and the ink circulates between the line head 20 and the sub tank 40. It is enough time. And it is detected by step S17 shown in FIG. 10 whether it is drive time> = t2, and if drive time> = t2, it will transfer to following step S18 and will stop the rotational drive of the transfer pump 50. FIG. Thus, ink can be supplied to the line head 20 and air can be removed (bubbles in the ink can be removed), and ink supply in step S19 is completed.

  After supplying ink to the line head 20 in this way, the sub tank 40 is replenished with ink. Specifically, as in step S1 shown in FIG. 7, ink filling (replenishment) to the sub tank 40 is started, and the ink cartridge 30 side of the three-way valve 60 is set to “open” in steps S2 and S3. . Next, the air release valve 41 is set to “open” in steps S4 and S5. In step S6, the transfer pump 50 is driven to rotate in the CW direction (clockwise), and the ink in the sub tank 40 is filled. As a result, ink can be ejected from the nozzles 21 of the line head 20. Further, when ink is ejected from the nozzles 21, the ink in the sub tank 40 is consumed. Therefore, the sub tank 40 is continuously replenished with ink.

  Therefore, the ink jet printer 10 according to the present embodiment has only one transfer pump 50 by switching the three-way valve 60 (whether the line head 20 side is “open” or the ink cartridge 30 side is “open”). Ink supply and ink filling (replenishment) can be performed. Therefore, size reduction and cost reduction can be achieved. In addition, since the ink transfer path is simplified and the number of pipes can be reduced, the reliability can be improved.

FIG. 13 is a conceptual diagram showing a piping system for one color of the printing section in the ink jet printer 10 of the present embodiment, and shows a state in the middle of refilling the line head 20 with ink.
As shown in FIG. 13, the inkjet printer 10 performs printing by ejecting ink droplets from the nozzles 21 of the line head 20 toward the recording paper 100. Therefore, the same amount of ink as the ejected ink droplet is supplied from the sub tank 40 to the line head 20. In addition, the sub tank 40 is supplemented with ink from the ink cartridge 30.

  Here, the sub tank 40 not only separates air (removes bubbles in the ink) but also acts to apply a certain negative pressure to the ink in the line head 20. Specifically, it is installed below the nozzle 21 of the line head 20 and temporarily stores ink at that position. Therefore, if the air release valve 41 is “open”, the pressure in the line head 20 is a predetermined negative pressure (water head differential pressure) generated by a water head difference corresponding to the liquid level of the ink in the sub tank 40. To be kept. As a result, the ink is prevented from leaking out from the nozzle 21 and the ink is stably ejected.

  Therefore, the replenishment of the ink to the sub tank 40 can not only discharge ink continuously from the nozzle 21, but also stabilize the ink pressure in the line head 20 against the atmospheric pressure while preventing ink leakage from the nozzle 21. It is possible to maintain the negative pressure within a range where ink can be ejected. Ink replenishment can be performed while printing (ink ejection) is stopped or during printing.

FIG. 14 is a graph schematically showing a change in negative pressure (water head differential pressure h) in the line head 20 in the inkjet printer 10 (see FIG. 13) of the present embodiment.
In the graph shown in FIG. 14, the pressure range Δh is a range between a minimum allowable negative pressure and a maximum allowable negative pressure that can stably eject ink while preventing ink leakage from the nozzle 21 (see FIG. 13). Means. Therefore, the pressure of the ink in the line head 20 with respect to the atmospheric pressure needs to be maintained at a negative pressure within the range of Δh. T = transfer pump 50 drive interval, t and t ′ = transfer pump 50 drive time.

  Here, first, it is assumed that the ink in the sub tank 40 (see FIG. 13) is in a full state (the water head differential pressure h shown in FIG. 14A is in the state (a)). This state is in the range of Δh where the negative pressure is slightly larger than the minimum allowable negative pressure. Therefore, if the sub tank 40 is full of ink (the water head differential pressure h is (a)), the ink does not leak out from the nozzle 21 (see FIG. 13), and the ink can be ejected stably. .

  Thereafter, as shown in FIG. 13, when the inkjet printer 10 starts printing, ink droplets are ejected from the nozzles 21 of the line head 20. As a result, the same amount of ink as the ejected ink droplet is supplied from the sub tank 40 to the line head 20, and the liquid level of the ink in the sub tank 40 is lowered. Therefore, the water head difference between the line head 20 and the sub tank 40 increases, and the water head differential pressure h changes from the state (a) to the state (b) as shown in FIG. If the printing is continued as it is, the water head difference further increases and the water head differential pressure h becomes the state (b ′), which exceeds the maximum allowable negative pressure and falls outside the range of Δh.

  Therefore, the transfer pump 50 is periodically driven to replenish the sub tank 40 (see FIG. 13) with ink. Specifically, the maximum ink consumption (for example, the ink consumption when printing with the maximum ejection amount) is assumed in advance, and the driving interval T is set so that Δh does not exceed the maximum consumption. The transfer pump 50 is driven. Thereby, the liquid level height of the ink in the sub tank 40 is increased, the head difference is reduced, and the head differential pressure h can be maintained in the range of Δh.

  The drive time t for driving the transfer pump 50 is the sub tank 40 (FIG. 13) that can maintain the transfer amount of ink per unit time of the transfer pump 50 within V and the negative pressure of ink in the line head 20 within the range of Δh. The transfer pump 50 is driven and controlled by a control device (not shown) so that t ≧ (Q / V) where Q is the amount of ink change in the reference). Note that when the transfer pump 50 is driven when printing (ink discharge) is stopped, t ≧ (Q / V) may be satisfied. However, when the transfer pump 50 is driven during printing, the ink consumed by printing is also reduced. Since it is necessary to replenish, t ≧ (2Q / V).

  As described above, when the ink is replenished by the transfer pump 50 for the time t ≧ (Q / V) (or t ≧ (2Q / V)), as shown in FIG. ) Or more. Then, the ink is returned from the sub tank 40 to the ink cartridge 30 by the return pipe 86. Therefore, the head differential pressure h is changed from the state (b) shown in FIG. 14A to the state (c) (the ink in the sub tank 40 is full and the head differential pressure h is the same as (a)). . Thereby, the negative pressure does not become smaller than the minimum allowable negative pressure, and the water head differential pressure h is maintained within the range of Δh.

  When the ink jet printer 10 (see FIG. 13) continues printing (discharge of ink droplets from the line head 20), the ink level in the sub tank 40 (see FIG. 13) drops again, and the line head The water head difference with 20 becomes large. However, since the transfer pump 50 is driven at the drive interval T, the transfer pump 50 is driven for the drive time t when the head differential pressure h changes from the state (c) to the state (d). Therefore, the hydraulic head differential pressure h is returned to the state (e) within the range of Δh. Similarly, when the water head differential pressure h changes from the state (e) to the state (f) due to the ejection of ink droplets, the water head differential pressure h returns from the state (f) to the state (g) by replenishing ink. It is.

  Therefore, even if ink droplets are ejected from the line head 20 and the ink in the sub tank 40 (see FIG. 13) is consumed, the transfer pump 50 is driven at the driving interval T for the driving time t as shown in FIG. By driving repeatedly, the sub tank 40 can be appropriately refilled with ink. As a result, the pressure of the ink in the in-head 20 is maintained at a negative pressure in an appropriate range with respect to the atmospheric pressure (water head differential pressure h in the range of Δh).

  Further, the transfer pump 50 may not be driven periodically at the drive interval T, but may be driven when the maximum allowable negative pressure within the range of Δh is changed. FIG. 14B is a graph in the case where the transfer pump 50 is driven and controlled in this way, and the change in the water head differential pressure h is separately detected using a pressure sensor or the like. Specifically, the ink in the sub tank 40 (see FIG. 13) is greatly reduced from the full state (the head differential pressure h is in the state (h)), and the negative pressure in the line head 20 reaches the maximum allowable negative pressure. When it is detected that the state (the head differential pressure h is in the state (i)) is detected, the transfer pump 50 is driven. Thereby, the liquid level height of the ink in the sub tank 40 is increased, the head difference is reduced, and the head differential pressure h can be maintained in the range of Δh.

  Here, as shown in FIG. 9, the drive time t ′ of the transfer pump 50 is such that the ink in the sub-tank 40 exceeds a certain amount (full) and the ink is returned from the sub-tank 40 to the ink cartridge 30 by the return pipe 86. It is set to the time until it becomes. Therefore, the head differential pressure h changes from the state (i) shown in FIG. 14B to the state (j) (the ink in the sub tank 40 is full and the head differential pressure h is the same as (h)). . Thereby, the negative pressure does not become smaller than the minimum allowable negative pressure, and the water head differential pressure h is maintained within the range of Δh. Similarly, when the water head differential pressure h is changed from the state (j) to the state (k) by the ejection of the ink droplet, the water head differential pressure h is returned from the state (k) to the state (l) by replenishing ink. It is.

  Therefore, even if ink droplets are ejected from the line head 20 and the ink in the sub tank 40 (see FIG. 13) is consumed, as shown in FIG. By driving the transfer pump 50 for the drive time t ′, the sub tank 40 can be appropriately refilled with ink. As a result, the pressure of the ink in the in-head 20 is maintained at a negative pressure in an appropriate range with respect to the atmospheric pressure (water head differential pressure h in the range of Δh). Note that the driving of the transfer pump 50 may be continued even when printing (ink ejection) is stopped. Further, the transfer pump 50 may be always driven.

  Incidentally, the inkjet printer 10 (see FIG. 2) of the present embodiment performs color printing using four colors of ink. Therefore, four line heads 20 and sub tanks 40 (see FIG. 2) are arranged for each color of ink. However, when printing is performed, the amount of ink consumed for each color is not necessarily the same, so the liquid level of the ink in each sub tank 40 varies. Thereby, the negative pressure in each line head 20 is not constant.

FIG. 15 is a cross-sectional view showing the liquid level height of the ink in the four sub tanks 40 in the inkjet printer 10 (see FIG. 2) of the present embodiment.
As shown in FIG. 15A, when printing (ink ejection) is performed by the inkjet printer 10, the sub tanks 40 (Y), The liquid level of the ink changes for each of the sub tank 40 (M), the sub tank 40 (C), and the sub tank 40 (K). If printing is continued as it is, in the sub tank 40 (K) where the most ink is consumed, the water head differential pressure h is the maximum allowable negative pressure as in the state (b ′) shown in FIG. Beyond the range of Δh.

  Therefore, as shown in FIG. 13, the transfer pump 50 is driven to replenish ink from the ink cartridge 30 to the sub tank 40. Specifically, one drive motor 51 is controlled by a control device (not shown), and the four transfer pumps 50 are driven simultaneously (for example, as shown in FIG. drive only t). Therefore, as shown in FIG. 15A, the ink is replenished simultaneously to the four sub tanks 40 (Y, M, C, K) having different liquid surface heights.

  In this case, ink is replenished for the same amount of time to both the sub tank 40 (K) with the least ink and the sub tank 40 (C) with the most ink remaining. However, as shown in FIG. 9, when the ink in the sub-tank 40 reaches a certain amount (full) or more, the ink is returned from the sub-tank 40 to the ink cartridge 30 by the return pipe 86, so that the sub-tank 40 shown in FIG. Even if the ink is replenished until (K) is full, the ink does not overflow from the sub tank 40 (C). As a result, as shown in FIG. 15B, the liquid level height of the ink in the four sub tanks 40 (Y, M, C, K) is the same.

  As described above, before exceeding the maximum allowable negative pressure (see FIG. 14), the ink is replenished in accordance with the sub tank 40 (K), which takes the longest time among the four sub tanks 40 (Y, M, C, K). In this case, all the sub tanks 40 (Y, M, C, K) are full. Therefore, it is not necessary to replenish ink independently to each sub tank 40 (Y, M, C, K). Then, with respect to the four line heads 20 (see FIG. 2), the pressure of the ink in each line head 20 is set to a negative pressure in the appropriate range with respect to the atmospheric pressure (within the range of Δh shown in FIG. 14). The water head differential pressure h) can be maintained. In addition, since the four transfer pumps 50 (see FIG. 2) for replenishing ink to the sub tanks 40 (Y, M, C, K) can be driven by one drive motor 51 (see FIG. 2), the size and cost can be reduced. Can be achieved.

  Further, when printing (ink ejection) is performed by the ink jet printer 10 (see FIG. 13), not only the ink in each sub tank 40 (Y, M, C, K) is consumed but also bubbles are included in the ink. It comes to be. As a result, even if each sub tank 40 (Y, M, C, K) is replenished with ink and the water head differential pressure h within the range of Δh shown in FIG. 14 is maintained, the ink ejection stability deteriorates. Therefore, by circulating the ink, bubbles in the ink are removed in each sub tank 40 (Y, M, C, K).

FIG. 16 is a flowchart showing a flow of removing bubbles in the ink in the line head 20 in the inkjet printer 10 (see FIG. 3) of the present embodiment.
FIG. 17 is a conceptual diagram showing a piping system for one color of the printing section in the ink jet printer 10 of this embodiment, and shows a state in which bubbles in the ink in the line head 20 are removed.

  In order to remove bubbles in the ink in the line head 20, the ink is circulated between the line head 20 and the sub tank 40 as shown in FIG. Specifically, when the ink circulation of the line head 20 is started in step S21 shown in FIG. 16, it is detected in the next step S22 whether or not the line head 20 side of the three-way valve 60 is “open”. Is done. If it is not “open”, the process branches to step S23, and the line head 20 side is switched to “open”. The three-way valve 60 shown in FIG. 17 shows a state in which the line head 20 side is “open”.

  If the line head 20 side of the three-way valve 60 is “open”, the process proceeds to step S24 to detect whether or not the atmosphere release valve 41 of the sub tank 40 (see FIG. 17) is “open”. Is done. If it is not “open”, the process branches to step S25, and the atmosphere release valve 41 is switched to “open”. Note that the atmosphere release valve 41 shown in FIG. 17 is in an “open” state.

  Thus, after the line head 20 side of the three-way valve 60 is set to “open” and the atmosphere release valve 41 is set to “open”, the transfer pump 50 is rotationally driven in the CW direction (clockwise) in step S26. . In addition, the transfer pump 50 shown in FIG. 17 has shown the state currently rotationally driven by the drive motor 51 controlled by the control apparatus (not shown) in the CW direction (clockwise).

  When the transfer pump 50 is rotationally driven in the CW direction (clockwise), the ink is transferred in the forward direction (CW direction) as indicated by an arrow in the transfer pump 50 shown in FIG. Thereby, the bubbles in the ink in the line head 20 are transferred together with the ink, and as shown by the arrows in FIG. 17, the discharge pipe 88, the three-way valve 60, the transfer pipe 82, the check valve array 70, the transfer pipe. 83, the transfer pump 50, the transfer pipe 84, the check valve array 70, the transfer pipe 85, and the filter 91 are transferred to the sub tank 40. Then, the bubbles in the ink transferred to the sub tank 40 are removed from the ink by buoyancy, and are separated from the ink and gas. As a result, bubbles are removed from the ink, and only ink that does not contain bubbles is stored in the sub tank 40.

  In addition, the negative pressure increases in the line head 20 due to the transfer of ink. As a result, the reduced amount of ink from the line head 20 is supplied from the sub tank 40 to the line head 20 through the supply pipe 87 and the filter 92. The supplied ink contains no bubbles. Therefore, the ink in the line head 20 is transferred to the sub tank 40, and the ink in the sub tank 40 is supplied to the line head 20 (the ink is circulated between the line head 20 and the sub tank 40). And bubbles in the ink transfer path are removed by the sub tank 40. Further, the inside of the line head 20 is maintained at a negative pressure corresponding to the water head difference with the liquid level of the ink in the sub tank 40.

  Here, the drive time t3 of the transfer pump 50 (drive motor 51) is such that the ink circulates (the ink originally in the line head 20 returns to the line head 20 again through the sub tank 40). It is enough time. And it is detected by step S27 shown in FIG. 16 whether it is drive time> = t3, and if drive time> = t3, it will transfer to following step S28 and will stop the rotational drive of the transfer pump 50. FIG. Thereby, the bubbles in the ink in the line head 20 can be removed, and the ink circulation in step S29 is completed.

FIG. 18 is a flowchart showing the flow of removing bubbles in the ink near the nozzle 21 (see FIG. 3) in the inkjet printer 10 (see FIG. 3) of the present embodiment.
FIG. 19 is a conceptual diagram showing a piping system for one color of the printing portion in the ink jet printer 10 of this embodiment, and shows a state in which bubbles in the ink near the nozzle 21 are removed.

  In order to remove bubbles in the ink near the nozzle 21, as shown in FIG. 19, the ink is sucked from the nozzle 21 toward the head cap 22, and the ink is circulated between the head cap 22 and the sub tank 40. Specifically, when ink suction of the line head 20 is started in step S31 shown in FIG. 18, it is detected in next step S32 whether or not the head cap 22 is “closed”. If it is not “closed”, the process branches to step S33, and the head cap 22 is switched to “closed” by an opening / closing device (not shown) of the head cap 22, and the nozzle 21 side of the line head 20 is switched to the head cap 22. Seal with. Note that the head cap 22 shown in FIG. 19 is in a “closed” state.

  If the head cap 22 is “closed”, the process proceeds to step S34 to detect whether the line head 20 side of the three-way valve 60 is “open”. If it is not “open”, the process branches to step S35, and the line head 20 side is switched to “open”. Note that the three-way valve 60 shown in FIG. 19 shows a state in which the line head 20 side is “open”.

  Furthermore, if the line head 20 side of the three-way valve 60 is “open”, the process proceeds to step S36, and whether or not the atmosphere release valve 41 of the sub tank 40 (see FIG. 19) is “open”. Detected. If it is not “open”, the process branches to step S37, and the atmosphere release valve 41 is switched to “open”. Note that the atmosphere release valve 41 shown in FIG. 19 is in an “open” state.

  Thus, after the head cap 22 is “closed”, the line head 20 side of the three-way valve 60 is “open”, and the atmosphere release valve 41 is “open”, in step S38, the CCW direction (counterclockwise) The transfer pump 50 is driven to rotate. In addition, the transfer pump 50 shown in FIG. 19 has shown the state currently rotationally driven by the drive motor 51 controlled by the control apparatus (not shown) in the CCW direction (counterclockwise).

  When the transfer pump 50 is rotationally driven in the CCW direction (counterclockwise), the ink is transferred in the reverse direction (CCW direction) as indicated by an arrow in the transfer pump 50 shown in FIG. Therefore, the check valve array 70 forms a transfer path in which ink enters from the discharge pipe 89 connected to the head cap 22 and exits from the transfer pipe 84 toward the transfer pump 50. Further, a transfer path is formed in which ink enters from the transfer pipe 83 and exits from the transfer pipe 85 toward the sub tank 40. If foreign matter or the like is mixed in the transferred ink, it is removed by the filter 93 before entering the check valve array 70.

  Therefore, when the ink is transferred in the reverse direction (CCW direction), the pressure in the head cap 22 decreases, and the ink in the line head 20 is sucked from the nozzle 21. As a result, bubbles near the nozzle 21 are collected in the head cap 22 together with the ink. The ink containing bubbles in the head cap 22 is discharged from the discharge pipe 89, the filter 93, the check valve array 70, the transfer pipe 84, the transfer pump 50, the transfer pipe 83, and the check valve as shown by the arrows in FIG. It is transferred to the sub tank 40 through the array 70, the transfer pipe 85, and the filter 91. As a result, bubbles in the ink come out of the ink by buoyancy and are separated from the ink by gas-liquid separation, so that the bubbles are removed from the ink. As a result, only ink that does not contain bubbles is stored in the sub tank 40.

  Further, the suction of ink from the nozzles 21 increases the negative pressure in the line head 20. As a result, the reduced amount of ink from the line head 20 is supplied from the sub tank 40 to the line head 20 through the supply pipe 87 and the filter 92. Further, bubbles are not mixed in the supplied ink. Further, the inside of the line head 20 is maintained at a negative pressure corresponding to the water head difference with the liquid level of the ink in the sub tank 40.

  Here, the drive time t4 of the transfer pump 50 (drive motor 51) is such that the ink circulates (the ink originally in the line head 20 is sucked from the nozzle 21 toward the head cap 22 and passes through the sub tank 40. It is enough time to return to the line head 20 again. Then, in step S39 shown in FIG. 18, it is detected whether or not the drive time is greater than or equal to t4. If the drive time is greater than or equal to t4, the process proceeds to the next step S40 and the rotation drive of the transfer pump 50 is stopped. Thereby, bubbles in the ink near the nozzle 21 can be removed, and the ink suction in step S41 is completed.

  Moreover, the line head 20 side of the three-way valve 60 is “open” by step S34 and step S35. Therefore, if the transfer pump 50 is rotationally driven in the CCW direction (counterclockwise) as in step S38, relatively small bubbles in the ink near the nozzle 21 can be removed. On the other hand, if the transfer pump 50 is rotationally driven in the CW direction (clockwise) as in step S26 shown in FIG. 16, relatively large bubbles in the ink in the line head 20 can be removed. Therefore, all the bubbles in the ink can be removed simply by reversing the driving direction of the transfer pump 50. Furthermore, since not only the ink in the line head 20 but also the ink sucked by the head cap 22 can be circulated and returned to the line head 20, useless ink consumption can be reduced.

The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications such as the following are possible.
(1) In this embodiment, as an example of the liquid supply device and the liquid discharge device, the inkjet printer 10 including the line head 20 for the print width is given as an example. However, the inkjet printer 10 is not limited to such an inkjet printer 10 and may be a serial head type inkjet printer. Further, the present invention can be widely applied to other liquid ejecting apparatuses that eject various liquids (for example, a liquid ejecting apparatus that ejects dye to a dyed product).

  (2) In the present embodiment, the transfer pump 50 is exemplified by a tube pump that transfers the ink by continuously elastically deforming the elastic tube. However, the pump is not limited to the tube pump, and may be another type of pump (for example, a piston pump).

1 is a side view illustrating an outline of an inkjet printer according to an embodiment. It is a perspective view which shows the printing part of the inkjet printer of this embodiment. It is a conceptual diagram which shows the piping system for 1 color of the printing part in the inkjet printer of this embodiment. It is sectional drawing and a perspective view which show a line head partially. It is sectional drawing which shows the non-return valve array in the inkjet printer of this embodiment, and has shown the state which circulates the ink in a line head. It is sectional drawing which shows the non-return valve array in the inkjet printer of this embodiment, and has shown the state which circulates the ink attracted | sucked by the head cap. It is a flowchart which shows the flow of the ink filling to the sub tank in the inkjet printer of this embodiment. It is a conceptual diagram which shows the piping system for 1 color of the printing part in the inkjet printer of this embodiment, and shows the state in the middle of the ink filling to a sub tank. FIG. 3 is a conceptual diagram illustrating a piping system for one color of a printing unit in the ink jet printer according to the present embodiment, and illustrates a state at the end of ink filling in a sub tank. 3 is a flowchart illustrating a flow of ink supply to a line head in the ink jet printer according to the embodiment. FIG. 3 is a conceptual diagram illustrating a piping system for one color of a printing unit in the ink jet printer according to the present embodiment, and shows a state in the middle of ink supply to a line head. FIG. 3 is a conceptual diagram illustrating a piping system for one color of a printing unit in the ink jet printer according to the present embodiment, and illustrates a state when ink supply to a line head is finished. FIG. 3 is a conceptual diagram illustrating a piping system for one color of a printing unit in the ink jet printer according to the present embodiment, and illustrates a state in the middle of ink replenishment to the line head. It is a graph which shows typically change of the negative pressure (water head differential pressure h) in a line head in the ink jet printer of this embodiment. It is sectional drawing which shows the liquid level height of the ink in four sub tanks in the inkjet printer of this embodiment. It is a flowchart which shows the flow of the bubble removal in the ink in the line head in the inkjet printer of this embodiment. It is a conceptual diagram which shows the piping system for 1 color of the printing part in the inkjet printer of this embodiment, and shows the state which removes the bubble in the ink in a line head. It is a flowchart which shows the flow of the bubble removal in the ink of the ink jet printer vicinity of this embodiment. It is a conceptual diagram which shows the piping system for 1 color of the printing part in the inkjet printer of this embodiment, and shows the state which removes the bubble in the ink of the nozzle vicinity.

Explanation of symbols

10 Inkjet printer 15 Detachable pedestal 20 Line head (consumption object and liquid discharge head)
20a Supply port 20b Discharge port 21 Nozzle 22 Head cap 30 Ink cartridge (liquid tank)
40 Sub tank (auxiliary tank)
41 Atmospheric release valve 50 Transfer pump 51 Drive motor (drive source)
60 three-way valve 70 check valve array 71 first inlet 72 second inlet 73 first outlet 86 return pipe 87 supply pipe 88 discharge pipe 93 filter

Claims (7)

A liquid tank storing liquid to be supplied to a liquid consumption target;
A transfer pump for transferring the liquid stored in the liquid tank;
A supply pipe piped to supply the liquid transferred by the transfer pump to the consumption object;
A discharge pipe that is piped to discharge liquid that has not been consumed by the consumption object from the consumption object;
A three-way valve disposed between the liquid tank and the discharge pipe and the transfer pump and capable of switching between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump; ,
An auxiliary tank for temporarily storing the liquid transferred by the transfer pump before supplying it to the consumption object;
Wherein when it is stored in the auxiliary tank liquid exceeds a specific amount, have a piping to the return pipe to return the liquid to the liquid tank from the auxiliary tank,
When the three-way valve switches the flow path from the liquid tank to the transfer pump, the liquid in the liquid tank passes through the three-way valve, the transfer pump, the auxiliary tank, and the return pipe in this order. A liquid transfer path returning to the liquid tank is configured,
When the three-way valve switches the flow path from the discharge pipe to the transfer pump, the liquid discharged from the consumption object to the discharge pipe is the three-way valve, the transfer pump, the auxiliary tank, the supply pipe the liquid supply device the transfer path of the liquid back to the consumption target via the sequentially Ru consists of. A liquid discharge head capable of discharging the supplied liquid from the nozzle;
A liquid tank storing liquid discharged by the liquid discharge head;
A transfer pump for transferring the liquid stored in the liquid tank;
A supply pipe piped to supply the liquid transferred by the transfer pump to a supply port provided in the liquid discharge head;
A discharge pipe piped to discharge the liquid in the liquid discharge head from a discharge port provided on the opposite side of the supply port;
A three-way valve disposed between the liquid tank and the discharge pipe and the transfer pump and capable of switching between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump; ,
An auxiliary tank for temporarily storing the liquid transferred by the transfer pump before supplying it to the liquid discharge head;
Wherein when it is stored in the auxiliary tank liquid exceeds a specific amount, have a piping to the return pipe to return the liquid to the liquid tank from the auxiliary tank,
When the three-way valve switches the flow path from the liquid tank to the transfer pump, the liquid in the liquid tank passes through the three-way valve, the transfer pump, the auxiliary tank, and the return pipe in this order. A liquid transfer path returning to the liquid tank is configured,
When the three-way valve switches the flow path from the discharge pipe to the transfer pump, the liquid discharged from the discharge port of the liquid discharge head to the discharge pipe is the three-way valve and the transfer pump. , the auxiliary tank, the supply pipe liquid discharge apparatus carrying route of the liquid back to the liquid ejection head from the supply port via the sequentially Ru consists of. The liquid ejection apparatus according to claim 2, wherein
A plurality of the liquid discharge heads, a plurality of the liquid tanks, a plurality of the transfer pumps, a plurality of the supply pipes, a plurality of the discharge pipes, and a plurality of the plurality of liquid discharge heads, which are respectively provided according to the type of liquid discharged from the nozzles A liquid ejection device having a three-way valve. The liquid ejection apparatus according to claim 3, wherein
A liquid discharge apparatus having one drive source capable of simultaneously driving a plurality of the transfer pumps provided. The liquid ejection apparatus according to claim 3, wherein
A liquid discharge apparatus having one operating source capable of simultaneously operating a plurality of the three-way valves provided. The liquid ejection apparatus according to claim 2 , wherein
A liquid discharge apparatus having an air release valve for releasing the gas in the auxiliary tank to the atmosphere . A liquid discharge head capable of discharging the supplied liquid from the nozzle;
A liquid tank storing liquid discharged by the liquid discharge head;
A transfer pump for transferring the liquid stored in the liquid tank;
A supply pipe piped to supply the liquid transferred by the transfer pump to a supply port provided in the liquid discharge head;
A discharge pipe piped to discharge the liquid in the liquid discharge head from a discharge port provided on the opposite side of the supply port;
A three-way valve disposed between the liquid tank and the discharge pipe and the transfer pump and capable of switching between a flow path from the liquid tank to the transfer pump and a flow path from the discharge pipe to the transfer pump; ,
A control device for controlling the drive of the transfer pump and the operation of the three-way valve;
An auxiliary tank for temporarily storing the liquid transferred by the transfer pump before supplying it to the liquid discharge head;
A return pipe piped to return the liquid from the auxiliary tank to the liquid tank when the liquid stored in the auxiliary tank reaches a predetermined amount or more;
Have
The control device drives the transfer pump in a state where the three-way valve is switched to a flow path from the liquid tank to the transfer pump, and transfers the liquid in the liquid tank to the three-way valve, the transfer pump, and the auxiliary The liquid in the auxiliary tank is kept constant in a full state by configuring a transfer path for returning the liquid to the liquid tank via the tank and the return pipe in this order,
The control device drives the transfer pump in a state where the three-way valve is switched to a flow path from the discharge pipe to the transfer pump, and the liquid in the liquid discharge head is discharged from the discharge port, the discharge pipe, A transfer path for returning the liquid to the liquid discharge head is formed through the three-way valve, the transfer pump, the auxiliary tank, the supply pipe, and the supply port in this order to circulate the liquid in the liquid discharge head.
Control method of liquid ejection apparatus .

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