JP4490497B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  Ink-jet ink may contain foreign matters formed by aggregation and alteration of components in the ink such as dust, pigments, base materials, and dispersants mixed during manufacture and refilling. Since foreign matter may destabilize the discharge operation of the print head, in order to perform stable discharge operation by removing foreign matter from the ink, the inkjet recording apparatus is usually provided with a filtering device such as a filter. (See, for example, Patent Document 1). When a filter is used, foreign matters larger than the maximum pore diameter are captured by the filter and accumulated on the surface of the filter primary side, so that they do not flow out to the filter secondary side.

  However, some of the foreign matters that are blocked and accumulated on the primary side of the filter may pass through the filter with chance while using the ink for a long time, or may pass through the filter at a large flow rate due to the nozzle recovery operation. During the recovery operation, the ink normally flows through the filter at a flow rate that is 10 times the maximum flow rate during printing, so that phenomena such as deformation of foreign matter and decomposition of aggregates are likely to occur, and such foreign matter may pass through the filter. .

When such foreign matter reaches the vicinity of the nozzle in the head, the discharge operation becomes unstable. Therefore, it is desirable to prevent foreign matter from flowing out to the filter secondary side as much as possible when performing the recovery operation of discharge. If it flows out to the secondary side of the filter, it is required to quickly discharge the foreign matter from the nozzle in order to continue a stable discharge operation.
JP 2001-105623 A

  An object of the present invention is to provide an ink jet recording apparatus that can avoid foreign substances from flowing out to the secondary side of a filter as much as possible.

An ink jet recording apparatus according to an aspect of the present invention includes an ink bottle containing ink,
A print head for recording by discharging the ink;
A printing ink supply path for supplying the ink from the ink bottle to the print head;
A first filtration device provided in the middle of the printing ink supply path and including a first filter;
A valve for closing the printing ink supply path between the ink bottle and the first filtration device;
A pressure applying mechanism that is provided between the ink bottle and the print head and applies a higher pressure to the ink than during normal printing;
A purge ink flow path that connects the ink bottle and the print head, supplies ink to which the high pressure is applied by the pressure applying mechanism to the print head, and purges the ink from the print head; Characterize

A purge method for an ink jet recording apparatus according to an aspect of the present invention includes: an ink bottle that contains ink; a print head that performs recording by discharging the ink; and a print that supplies the ink from the ink bottle to the print head An ink jet recording apparatus comprising: a printing ink supply path ; a filtration device provided in the middle of the printing ink supply path; and a valve that closes the printing ink supply path between the ink bottle and the filtration device. A purge method,
Providing a purge ink flow path for supplying the ink to the print head and purging the ink from the print head;
Printing is performed by applying atmospheric pressure to the ink bottle,
Closing the valve of the ink supply path for printing, applying a pressure higher than atmospheric pressure to the ink bottle, and purging the ink from the print head by applying a pressure higher than that during printing to the ink; To do.

  According to the aspect of the present invention, there is provided an ink jet recording apparatus capable of avoiding foreign matters from flowing out to the filter secondary side as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an ink supply system used in this embodiment. As shown in the drawing, the ink 12 contained in the ink bottle 11 passes through the primary side ink supply tube (supply pipe) 13, the filtering device 14, and the secondary side ink supply tube (supply pipe) 15. 16 is supplied.

  The filtration device 14 has an ink inlet 17 and an ink outlet 18, and a filter mesh 19 is provided in the ink supply path between them. The material of the filter mesh 19 is not particularly limited. For example, a material made of polypropylene or nitrocellulose can be used. The filter mesh 14 prevents passage of foreign matter in the ink.

  The maximum hole diameter of the filter is set according to specifications such as the nozzle diameter of the inkjet head, ink characteristics, ejection stability, and head life. In the recording apparatus according to the embodiment of the present invention, in order to perform a stable ejection operation, it is desirable that foreign matters having a size of 0.5 μm or more are not contained in the ink as much as possible. The larger the number of foreign matters, the greater the number of foreign matters, and the greater the effect on the discharge operation. In particular, foreign matters having a diameter of about the nozzle diameter or more will seriously affect the discharge operation. However, on the other hand, if the filter mesh (pore diameter) is set too fine, the discharge operation becomes unstable due to pressure loss when passing through the filter, and foreign matter and pigments of ink components are likely to be clogged, so the life of the filter becomes extremely short. End up. In particular, when the pore diameter is 3 μm or less, the pressure loss and the life are significantly affected. When the pore diameter is 0.5 μm or less, the color material in the ink is filtered.

  Therefore, the maximum pore diameter of the filter may be selected as appropriate according to the specifications of the head and ink in the range of about 3 μm to 30 μm. Here, a filter having a maximum pore diameter of 10 μm was used.

  In the illustrated filtration apparatus, the blind portions 20 are arranged above and below the filter mesh 19, thereby forming a foreign matter reservoir 21 on the primary side (upstream side). The blind portion 20 can be made of, for example, a polypropylene film. The primary side of the blind portion acts as a foreign matter reservoir portion 21 to attenuate the ink flow velocity, and the foreign matter once blocked by the filter mesh 19 is prevented from passing through the filter.

  A foreign substance present in the ink is removed by the filtration device 14, and a stable ejection operation can be performed. The foreign matter in the ink removed here includes not only a spherical solid but also an elongated shape and a deformable semi-solid.

  The printing operation in such an ink supply system will be described in detail below.

  Although not clearly shown in the figure, the print head 16 has a nozzle and an actuator, and when the actuator is driven at 5000 Hz, 40 pL (picoliter) of ink per dot is ejected at 5000 Hz (dots per second). The diameter of the nozzle used in this embodiment is 27 μm, and 500 nozzles are provided. The volume of ink from the filter secondary side to the nozzle is 3 ml.

The specific gravity of the ink stored in the ink bottle 11 is 1, and the height of the ink bottle 11 is controlled by the liquid level maintaining mechanism 22. The liquid level maintaining mechanism 22 detects the amount of ink in the ink bottle 11 with a weight sensor (not shown) and adjusts the ink bottle up and down. Specifically, even when the ink is consumed, the height difference H ₁ between the ink liquid level and the nozzle surface of the print head 16 is controlled to be maintained at 80 mm. Normally, when the ink bottle 11 is opened to atmospheric pressure and no ink is flowing, the ink pressure on the nozzle surface of the print head 16 is -800 Ps. This negative pressure forms a concave meniscus on the nozzle. When printing is performed, the negative pressure of the nozzle increases due to the flow path resistance of the ink path.

  The pressure loss of the primary side ink supply tube 13, the filtering device 14, the secondary side ink supply tube 15, and the print head 16 is 500 Pa, 4000 Pa, 1500 Pa, 4000 Pa (Pascal) per flow rate of 1 mL / s (milliliter per second), respectively. The total flow resistance from the ink bottle 11 to the print head 16 is 10,000 Pa s / mL (10000 Pa per 1 mL / s of flow rate).

  As illustrated, the ink bottle 11 is provided with a pressure gauge 24 and a pump 25 via an air filter 23. The pump 25 is used during ink filling and nozzle recovery operations. At the time of ink filling, air is sent to the ink bottle by the pump 25 so that the pressure in the ink bottle 11 becomes 10800 Pa. At this time, dust in the air is captured by the air filter 23 and is prevented from being mixed into the ink.

  Ink is filled into the print head 16 at a flow rate of 1 mL / s, and excess ink is discharged from the nozzles of the print head 16 through the cap 27 to the waste liquid bottle 28. After filling, the pump 25 is stopped and the ink bottle 11 is opened to the atmospheric pressure. Thereafter, when the excess ink adhering to the nozzles of the print head 16 is wiped off with the wiper 26, a negative meniscus is formed on the nozzle surface due to the negative pressure of −800 Pa, and discharge becomes possible.

  When the actuator of the print head 16 is driven, ink is ejected from the nozzles, and the ink consumed by the ejection is sucked up from the ink bottle 11. In this case, the ink flow rate becomes maximum when all the nozzles of the print head 16 continuously discharge at 5000 Hz, and is 40 pL / dot × 5000 Hz × 500 nozzle = 0.1 mL / s (milliliter per second). Since the total flow resistance from the ink bottle 11 to the head 16 is 10000 Pa s / mL (10000 Pa per 1 mL / s), the pressure loss of the ink path at the time of maximum printing is 1000 Pa.

  Therefore, the ink pressure on the nozzle surface of the head 16 varies between -800 Pa and -1800 Pa in non-printing to maximum printing. The nozzle hole shape of the print head 16 is designed so that a meniscus is stably formed in this negative pressure range.

  When the ink pressure on the nozzle surface exceeds an appropriate range on the positive pressure side, the periphery of the nozzle surface is soiled with ink, and the print quality deteriorates. On the other hand, when the ink pressure on the nozzle surface exceeds an appropriate range on the negative pressure side, air cannot be sucked out and discharged. During printing, paper dust may adhere to the nozzle surface, or air may be sucked in from the nozzles due to vibration, etc., or ink near the nozzle surface may become thickened, making it impossible to discharge. is there.

In such a case, the recovery operation is performed according to the following procedure.
The recovery operation is basically performed in the same procedure as in the case of ink filling. First, air is sent to the ink bottle by the pump 25 so that the pressure in the ink bottle 11 becomes 10800 Pa. At this time, the ink is discharged from the nozzle of the head 16 through the cap 27 to the waste liquid bottle 28 at a flow rate of 1 mL / s.

  After discharging about 1 mL of ink, the pump 25 is stopped and the ink bottle 11 is opened to atmospheric pressure. The foreign matter in the vicinity of the filter mesh settles at the lower part of the foreign substance reservoir or floats at the upper part. After 3 seconds, air is sent to the ink bottle by a pump so that the pressure of the ink bottle becomes 10800 Pa again. This operation is repeated three times, and the recovery operation is performed with a total of 3 mL of ink. Thereafter, when the excess ink adhering to the nozzles of the head 16 is wiped off with the wiper 26, a negative meniscus is formed on the nozzle surface due to the negative pressure of −800 Pa, thereby enabling ejection.

  When ink feeding and stopping are repeated as in the present embodiment, the foreign matter is sent to the foreign matter reservoir during the stop. As a result, it is possible to reduce the possibility that foreign matter passes through the filter mesh, compared to the case where the same amount of ink is fed at once. Ink may be made to flow backward after the ink has been fed and before stopping, in which case the risk of foreign matter flowing out is further reduced.

  The flow rate of the ink to be fed is desirably 2 to 20 times the maximum flow rate during printing. If the flow rate is less than twice the maximum flow rate, it is difficult to recover the cause of non-ejection. On the other hand, if the flow rate exceeds 20 times the maximum flow rate, the foreign matter in the foreign matter reservoir may be rolled up and passed through the filter. .

(Embodiment 2)
In the ink supply system shown in FIG. 1, foreign matter that has flowed out to the secondary side of the filter must be discharged from the nozzles of the print head. By discharging by the method of the present embodiment as described below, it is possible to make it difficult for foreign matter to remain on the nozzles of the print head.

  First, air is sent to the ink bottle 11 by the pump 25 so that the pressure in the ink bottle 11 becomes 10800 Pa. At this time, the ink is discharged from the nozzle of the head 16 through the cap 27 to the waste liquid bottle 28 at a flow rate of 1 mL / s. In this state, about 3 mL of ink is discharged. This is called a first discharging operation. At this time, since it is necessary to actively flow foreign matter that may flow out during printing, the ink flow rate in the first discharging operation needs to be larger than the maximum flow rate during printing.

  Thereafter, the pressure in the ink bottle 11 is controlled to 1800 Pa by rotating the pump 25 backward and forward. The flow rate of the ink is reduced to 0.1 mL / s, and about 5 mL is further discharged to the waste liquid bottle 28 in this state. This is called a second discharge operation. During this time, the ink flow rate in the second discharge operation is limited to be smaller than the flow rate in the first discharge operation in order not to move the residual foreign matter that has stopped moving in the first discharge operation more than necessary.

  By performing the first discharging operation, foreign matter on the primary side of the filter may be slightly discharged to the secondary side of the filter. This foreign matter is discharged from the nozzle to the waste liquid bottle 28 during the second discharging operation. In the second discharge operation, since the flow rate is as small as 0.1 mL / s, there is no risk of newly sending foreign matter on the filter primary side to the filter secondary side.

  When the second discharging operation is finished, the pump 25 is stopped and the ink bottle 11 is opened to the atmospheric pressure. Thereafter, when excess ink adhering to the nozzles of the head 16 is wiped off with the wiper 26, a meniscus is formed on the nozzle surface and printing is possible.

  Instead of applying a pressure of 1800 Pa to the ink bottle 11, the second discharge operation can be performed by driving the actuator of the print head 16 and discharging the ink toward the cap 27.

  Here, the flow rate of the faster one (first discharge operation) is 1 mL / s, but it is desirable that the flow rate be 2 to 20 times the maximum flow rate during printing. Within this range, the effects described in the first embodiment can be obtained. Further, it is desirable to keep the flow rate of the slower one (second discharge operation) below about the maximum flow rate during printing. If the maximum flow rate at the time of printing is exceeded, there is no possibility of starting to move during printing, and there is a possibility that the adhered foreign matter that should be left still will move to the flow path in a state where it can be moved and moved.

  Removing the accumulated foreign matter and not storing it in the print head are contradictory requirements, and this contradiction can be solved to some extent by the recovery operation of the second embodiment. The foreign matter can be removed from the staying place by the first discharge operation and discharged from the nozzle by the second discharge operation. Since the second discharging operation has a slow flow rate, there is little possibility that the foreign matter is newly wound up from the foreign matter reservoir. It is more effective if the first discharging operation and the second discharging operation are repeated a plurality of times.

  In Embodiments 1 and 2 described above, the filtration device 14 has a blind portion 20 and a foreign matter reservoir portion 21, but the blind portion and the foreign matter reservoir portion are not necessarily required. The recovery method as described above can also be applied to an ink supply system using a conventional filter, and foreign matter that has been discharged to the secondary side of the filter can be effectively discharged.

  Further, the present invention is not limited to foreign matters accumulated on the primary side of the filter, and can be effectively applied to the following cases. In the ink supply path, foreign matter tends to accumulate at portions where there is a rapid change in flow velocity or at the solid-liquid interface. Foreign substances may accumulate on the inner wall of the tube, the joint, the ink supply port of the print head, etc. for a long time. Foreign matter accumulated in this way can also be discharged by the method described above, making it difficult for foreign matter to remain in the nozzles of the print head.

(Embodiment 3)
FIG. 2 shows an ink supply system in the ink jet recording apparatus according to the present embodiment. The illustrated ink supply system is configured by drawing a loop of the ink bottle 11, the liquid feed pump 32, the second filtration device 30, the first filtration device 29, the valve 31, and the ink bottle 11, and the first filtration device. Ink is supplied to the print head 16 from between 29 and the second filtration device 30. Here, as the liquid feed pump 32, a type that closes the flow path when stopped is used, and as the first filtration device 29 and the second filtration device 30, a similar filter, a blind portion, and a foreign matter reservoir portion 21 are provided. What I have was used.

  The supply path reaching the print head 16 from the ink bottle 11 via the valve 31 and the first filtration device 29 is a print ink supply path for supplying ink to the print head. The flow path 33 reaching the print head 16 via the second filtration device 30 is a purge ink flow path.

  At the time of ink filling, first, ink is flowed in the order of the ink bottle 11, the liquid feed pump 32, the second filter 30, the first filter device 29, the valve 31, and the ink bottle 11 to fill the loop with ink. Next, the valve 31 is closed, and ink is supplied to the print head through the path of the ink bottle 11, the liquid feed pump 32, the second filtration device 30, and the print head 16.

  Thereafter, when the valve 31 is opened and the liquid feed pump 32 is stopped (the flow path is closed), a liquid level differential pressure of −800 Pa is applied to the nozzle surface of the print head 16, and when excess ink is removed by the wiper 26, the nozzle A meniscus is formed on the surface. When the actuator is operated from this state to perform the ejection operation, the ink is supplied to the print head 16 via the opened valve 31 and the first filtration device 29. That is, most of the ink stored in the ink bottle 11 finally passes through the first filter device 29 and is supplied to the print head 16 and consumed. Most of the foreign matter in the ink is accumulated in the foreign matter reservoir 21 of the first filtration device 29.

  On the other hand, the recovery operation is performed as follows. When the valve 31 is closed and the liquid feed pump 32 is operated, ink is sent through the path of the liquid feed pump 32, the second filtration device 30, and the print head 16. Thereafter, when the valve 31 is opened and the liquid feed pump 32 is stopped (the flow path is closed), a liquid level differential pressure of −800 Pa is applied to the nozzle surface of the print head 16, and when excess ink is removed by the wiper 26, the meniscus is applied. Is formed.

  In the recovery operation, the ink is supplied from the second filtration device 30 without going through the first filtration device 29. For this reason, the possibility that the foreign matter accumulated in the foreign matter reservoir 21 of the first filtration device 29 is wound up is reduced. In addition, since the second filtration device 30 is not used during printing, the cumulative amount of ink passing is much smaller than that of the first filtration device 29, and the amount of foreign matter remaining in the foreign matter reservoir 21 is also small. Therefore, a normal filter that does not have the blind portion 20 or the foreign substance reservoir portion 21 may be used as the second filtration device 30.

  If the ink supply path from the primary side of the first filtration device 29 to the valve 31 has a slight elasticity, the following effects can be obtained. When the valve 31 is opened at the end of the recovery operation, a slight flow is generated from the secondary side of the first filtration device 29 toward the primary side. At this time, the foreign matter adhering to the primary surface of the filter in the first filtering device 29 is pushed back, and settles or floats on the lower portion of the foreign matter reservoir according to the specific gravity. Can be guided to the department.

  In the present embodiment, since the supply of ink during printing is performed from the first filtration device 29 side, there is an advantage that the flow path resistance of the second filtration device 30 does not affect the ejection operation. Even if a filter having a large flow path resistance is used for the second filtration device 30, the range of the negative pressure on the nozzle surface during printing and at the time of stopping is not affected. Further, since the cumulative amount of ink passing through the second filtration device 30 is small, there is little possibility that pigments accumulate and aggregate and the filter is clogged even if the filter mesh in the second filtration device 30 is made fine. Therefore, a filter with a relatively fine mesh size can be selected as the filter of the second filtration device 30. For example, if a filter having a maximum pore diameter of 1 μm is used as a filter in the second filtration device 30, the risk of foreign matter flowing in from this filter can be further reduced. However, if the mesh size is too small, the color material in the ink may be filtered, so the maximum pore size of the filter used in the second filtration device 30 may be at least about 0.5 μm. desired.

(Embodiment 4)
FIG. 3 shows an ink supply system in the ink jet recording apparatus according to the present embodiment. The illustrated ink supply system includes an ink bottle 11, a liquid feed pump 32, a filtration device 14, and a print head 16, and these constitute an ink supply path for printing. The primary side of the filter is supplied with ink from the ink bottle 11 by a liquid feed pump (closed when stopped) 32. A purge tank 35, an air filter 37, a valve 38, an air chamber 39, and a pump 41 are provided on the filter secondary side of the filtration device, and these constitute a purge ink flow path.

The purge tank 35 is provided with a liquid level sensor 36 at a height (H ₂ ) of 20 mm from the nozzle surface of the print head 16. The ink volume up to the liquid level sensor 36 in the purge tank 35 is 50 mL. The flow path resistance from the purge tank 35 to the print head 16 is 1500 Pa per 1 mL / s. In the illustrated ink supply system, the air pressure in the air chamber 39 is controlled to control the ink pressure on the nozzle surface, and the liquid level maintaining mechanism for maintaining the liquid level in the ink bottle 11 is not used.

  When ink is filled, the pump 41 is stopped (open to the atmosphere) and the valve 38 is opened. The liquid feed pump 32 is rotated forward to supply ink to the purge tank 35 at a flow rate of 1 mL / s. During this time, the liquid level sensor 36 of the purge tank 35 is monitored, and the valve 38 is closed when the ink reaches the liquid level sensor.

  After this, the pump 41 is reversed to control the air chamber 39 to −1000 Pa. At the same time, ink is introduced into the print head 16 by the liquid feed pump 32, and excess ink is discharged from the nozzles through the cap 27 to the waste liquid bottle 28. After filling, the liquid feed pump 32 is stopped and the supply path from the ink bottle 11 is closed.

Next, when the surplus ink on the nozzle surface is wiped off with the wiper 26, a concave meniscus is formed on the nozzle surface with a negative pressure of −800 Pa, which is obtained by subtracting the liquid level difference from the air pressure in the air chamber 39, and printing becomes possible. During printing, the pressure gauge 40 always monitors the air pressure in the air chamber 39 and controls the pump 41 to keep the air pressure at -1000 Pa. At the same time, the liquid level sensor 36 is monitored, and when the ink falls below the liquid level sensor, the liquid feed pump 32 is rotated forward to replenish the ink so that the height (H ₂ ) from the nozzle surface to the liquid level is always maintained. Keep the position at 20 mm.

  The recovery operation is performed from the purge tank 35 side. The liquid feed pump 32 is stopped with the flow path closed. The pump 41 is rotated forward to pressurize the air chamber 39 and the air pressure is maintained at 5300 Pa. When the valve 38 is opened, the purge tank 35 is pressurized at 5300 Pa. The total flow resistance from the purge tank 35 to the nozzle surface is 5500 Pa per 1 mL / s. Since the pressure difference due to the liquid level difference is 200 Pa, the ink is discharged from the nozzle through the cap 27 to the waste liquid bottle 28 at a flow rate of 1 mL / s. When 3 mL is discharged, the valve 38 is closed, the pump 41 is reversed to decompress the air chamber 29, the air pressure is returned to -1000 Pa, and the valve 38 is opened again.

  At this time, since the ink in the purge tank 35 is consumed by the recovery operation, the liquid level is lower than the position of the sensor 36. The operation of the liquid feed pump 32 is resumed, ink is sent from the ink bottle, and the liquid level is returned to the sensor position. When the excess ink on the surface of the print head is wiped off with the wiper 26, a negative meniscus is formed on the nozzle surface due to the negative pressure of −800 Pa, thereby enabling ejection.

  In the present embodiment, as in the third embodiment, the ink flow during the recovery operation is different from the ink flow during printing. For this reason, there is no possibility that foreign matter accumulated in a portion having a large liquid contact area such as a foreign matter reservoir portion on the primary side of the ink will be wound up during the recovery operation.

Schematic showing the ink supply system used for one Embodiment of this invention. 1 is a schematic diagram illustrating an ink supply system in an ink jet recording apparatus according to an embodiment of the present invention. Schematic showing the ink supply system in the inkjet recording device concerning other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Ink bottle; 12 ... Ink; 13 ... Primary side ink supply tube 14 ... Filtration apparatus; 15 ... Secondary side ink supply tube; 16 ... Print head 17 ... Ink inlet port; 18 ... Ink outlet port; DESCRIPTION OF SYMBOLS 20 ... Blind part; 21 ... Foreign substance reservoir part; 22 ... Liquid level maintenance mechanism 23 ... Air filter; 24 ... Pressure gauge; 25 ... Pump; 26 ... Wiper 27 ... Cap; 30 ... Second filtration device 31 ... Valve; 32 ... Pump pump; 33 ... Purge flow path; 35 ... Purge tank 36 ... Liquid level sensor; 37 ... Air filter; 38 ... Valve; 39 ... Air chamber 40 ... Pressure gauge; 41 ... Pump.

Claims (3)

An ink bottle for containing ink;
A print head for recording by discharging the ink;
A printing ink supply path for supplying the ink from the ink bottle to the print head;
A first filtration device provided in the middle of the printing ink supply path and including a first filter;
A valve for closing the printing ink supply path between the ink bottle and the first filtration device;
A pressure applying mechanism that is provided between the ink bottle and the print head and applies a higher pressure to the ink than during normal printing;
A purge ink flow path that connects the ink bottle and the print head, supplies ink to which the high pressure is applied by the pressure applying mechanism to the print head, and purges the ink from the print head; An ink jet recording apparatus. The inkjet recording apparatus according to claim 1, further comprising a second filtration device provided in the purge ink flow path. An ink bottle that contains ink, a print head that discharges and records the ink, a printing ink supply path that supplies the ink from the ink bottle to the print head, and a middle of the printing ink supply path A purge method for an ink jet recording apparatus comprising: a filtration device provided; and a valve for closing the ink supply path for printing between the ink bottle and the filtration device,
Providing a purge ink flow path for supplying the ink to the print head and purging the ink from the print head;
Printing is performed by applying atmospheric pressure to the ink bottle,
Closing the valve of the ink supply path for printing, applying a pressure higher than atmospheric pressure to the ink bottle, and purging the ink from the print head by applying a pressure higher than that during printing to the ink; How to purge .

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