JPH08276604A - Ink jet printer and restoration of ink jet head - Google Patents

Abstract

PURPOSE: To certainly exclude air bubbles in an ink supply system causing the non-emission of ink in an ink jet printing to restore an ink jet head. CONSTITUTION: At the time of the restoring operation of an ink jet head, the ink in an ink supply passage is intermittently pressurized twice and, at the time of first pressurization in the direction indicated by arrow C, a stagnant air bubble B2 is hardly produced in the bent part 30A of an ink passage 30 by shortening the pressurizing time. When pressurization is stopped thereafter, the compression of air bubbles B1 is released to allow the air bubbles easy to move and, at the time of second pressurization, the air, bubbles B1 are certainly ejected along with ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can surely eliminate air bubbles in an ink supply system that cause non-ejection of ink, and in particular, eject ink from a large number of ink ejection ports such as a printing device. The present invention relates to an inkjet printing apparatus suitable for use in a printing apparatus and a method for recovering an inkjet head.

The present invention is applicable to all devices using print media such as paper, cloth, leather, non-woven fabric, OHP paper, and metal. Specific applicable equipment includes office equipment such as printers, copying machines, and facsimiles, and industrial production equipment.

[0003]

2. Description of the Related Art As one form of an ink supply system in a conventional image forming apparatus using an ink jet head, for example, one described in JP-A-56-89565 is known. This supply system is provided in a first container for preliminarily containing the ink to be supplied to the print head, and a path for supplying the ink in the container to the print head, and temporarily supplies the ink to be supplied. A second container for storing the ink, and according to the detection result of the ink remaining amount in the second container, the pump is driven to supply the ink from the first container to the second container, The amount of ink in the second container is maintained at a predetermined amount. As a measure against the surplus ink during the ink supply, the second container is provided with a structure for overflow.

By the way, if air bubbles exist in the ink supply system thus constructed and they move to the head, there is a risk that ink may not be ejected. For example, air bubbles that have entered the ink supply system at the time of refilling the ink may move to the head due to the ink flow, which may cause ink ejection failure. Therefore, it is necessary to remove the air bubbles that cause the non-ejection of the ink from the inside of the ink supply system and the inside of the head together with the ink ejection inhibiting factors such as the thickened ink.

Conventionally, as a method for removing such bubbles, there is a recovery method in which the ink supply system is continuously pressurized for a predetermined time so that the bubbles are discharged together with the ink from the ink discharge port of the head.

[0006]

However, in the case of the recovery method in which the ink is continuously pressurized for a predetermined time as in the above-mentioned conventional method, in particular, the bent portion of the ink flow path in the ink supply system or It is difficult to completely remove air bubbles in the ink supply system because air bubbles are likely to be accumulated in the filter section.

FIG. 12 shows the inside of the bent portion 30A of the ink flow path 30 when such a recovery method is carried out.

FIG. 12A shows a state in which the inside of the ink flow path 30 is continuously pressurized from the direction of arrow C for a predetermined period, and the bubbles B1 existing in the ink become the ink stagnant in the bent portion 30A. It is captured and becomes a bubble pool B2. The air bubble B1 thus captured is compressed by the ink flow pressure, and in this state, it is difficult to remove the air bubble pool B2 even if the ink pressurizing operation is continued. FIG. 12B shows a state when the pressurization of the ink is finished after that, and the compressed state of the bubble reservoir B2 is released, and it becomes a state in which it can easily move in the ink. After that, when the ink is supplied to the head from the direction of the arrow D along with the printing operation, the bubble B1 moves to the head by the ink flow as shown in FIG. 12C, which causes non-ejection of the ink.

FIG. 13 shows the inside of the filter portion 30B of the ink flow path 30 when such a recovery method is carried out. Reference numeral 31 is a filter for removing impurities in the ink. In the case of this example, the filter section 30B is provided in the flow path 30 of the ink supplied from the upper side to the lower side along the vertical direction.

FIG. 13A shows a state in which the inside of the ink flow path 30 is continuously pressurized from the direction of the arrow C for a predetermined period, and the bubbles B1 existing in the ink become the ink stagnant in the filter portion 30B. It is captured and becomes a bubble pool B2. The air bubble B1 thus captured is compressed by the ink flow pressure, and in this state, it is difficult to remove the air bubble pool B2 even if the ink pressurizing operation is continued. FIG. 13B shows a state when the pressurization of the ink is finished after that, and the compressed state of the bubble reservoir B2 is released, and it becomes a state in which it easily moves in the ink. After that, when the ink is supplied to the head from the direction of the arrow D along with the printing operation, the bubble B1 moves to the head by the ink flow as shown in FIG. 13C, which causes non-ejection of the ink.

An object of the present invention is to provide an ink jet printing apparatus and a method for recovering an ink jet head, which can surely eliminate air bubbles in an ink supply system which causes non-ejection of ink.

[0012]

An inkjet printing apparatus of the present invention is an inkjet printing apparatus which uses an inkjet head for ejecting ink and ejects the ink from the inkjet head onto a print medium to perform printing. Supply means for supplying ink to the head; pressurizing means for pressurizing the ink in the ink supply path between the inkjet head and the supply means; and the pressurizing means during recovery operation of the inkjet head. And a control unit that controls the pressure in the ink supply path to be intermittently applied a plurality of times to discharge the ink in the inkjet head to the outside of the inkjet head.

The method for recovering an ink jet head of the present invention is the method for recovering an ink jet head in an ink jet printing apparatus, wherein an ink jet head for ejecting ink is used, and ink is ejected from the ink jet head onto a print medium for printing. It is characterized in that the ink in the ink jet head is discharged to the outside of the ink jet head by intermittently pressurizing the ink in the ink supply path for supplying the ink to the ink jet head.

[0014]

According to the present invention, the ink supply path is intermittently pressed to perform the recovery operation of the ink jet head, thereby reliably removing bubbles that tend to stay in the bent portion in the ink flow path.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) (1) Description of Overall Configuration of Apparatus FIG. 1 shows a schematic configuration of a textile printing apparatus as an example of an inkjet printing apparatus to which the present invention can be applied. In the figure, reference numeral 1 is a cloth as a recording medium (print medium), which is unwound in accordance with the rotation of the unwinding roller 11 and is located at a portion facing the printer unit 1000 via the intermediate rollers 13 and 15. After being conveyed in a substantially horizontal direction by the provided conveying unit 100, it is taken up by the take-up roller 21 via the feed roller 17 and the intermediate roller 19.

The transport section 100 is generally configured as transport rollers 110 and 120 provided upstream and downstream of the printer section 1000 in the transport direction of the cloth 1, and a transport belt in the form of an endless belt wound between these rollers. 130, and a pair of platen rollers 140 provided to improve the flatness by stretching the conveyor belt 130 with an appropriate tension in a predetermined range in order to regulate the printed surface of the cloth to be flat when printing by the printer unit 1000. ing. In this example, the conveyor belt 130 is made of metal as disclosed in Japanese Unexamined Patent Publication No. 5-212851, and as shown in a partially enlarged view of FIG. Layer (sheet)
133 is provided. Then, the cloth 1 is adhered to the adhesive layer 133 of the conveyor belt 130 by the application roller 150, and the flatness at the time of printing is secured.

The cloth 1 conveyed in such a state where the flatness is ensured is provided with a printing agent by the printer unit 1000 in the area between the platen rollers 140, and the conveyor belt 130 or the adhesive is adhered to the portion of the conveyor roller 120. Although it is peeled off from the layer 133 and taken up by the take-up roller 21, the drying process is performed by the drying heater 600 on the way. As the drying heater 600, one having an appropriate form such as one that blows warm air to the cloth 1 or one that irradiates infrared rays can be used.

(2) Description of the structure of the printer unit FIG. 2 is a perspective view schematically showing the printer unit 1000 and the conveyance system of the cloth 1, and FIG. 3 is a sectional view showing the scanning system of the carriage. 2 and FIG. 3, the printer unit 1
000 will be described.

First, in FIGS. 1 and 2, the printer section 1000 is scanned in a direction different from the conveyance direction (sub-scanning direction) F of the cloth 1, for example, in the width direction S of the cloth 1 orthogonal to the conveyance direction F. It has a carriage 1010. 1
Reference numeral 020 is a support rail extending in the S direction (main scanning direction), and supports the slide rail 1022. The slide rail 1022 supports and guides the slider 1012 fixed to the carriage 1010. 1030
Is a motor serving as a driving source for performing main scanning of the carriage 1010, and its driving force is
Is transmitted to the carriage 1010 via a belt 1032 to which is fixed and other appropriate transmission mechanism.

The carriage 1010 holds a plurality of print heads 1100 having a plurality of ink ejection openings arranged in a predetermined direction (conveying direction F in this example) in a direction different from the predetermined direction (main scanning direction S in this example). Moreover, in this example, this is held in two stages in the transport direction. A plurality of print heads 1100 in each stage are provided corresponding to inks of different colors, which enables color printing. The color of the ink and the number of print heads can be appropriately selected according to the image or the like to be formed on the cloth 1. For example, the three primary colors of printing are yellow (Y), magenta (M) and cyan (C), or In addition to this, black (B
k) can be added. Alternatively, or in addition to them, special colors (metal colors such as gold and silver, vivid red, blue, etc.) that cannot be expressed or are difficult to express in the three primary colors can be used. Alternatively, a plurality of inks may be used depending on the densities of the same color.

In this example, a plurality of print heads 1100 arranged in the main scanning direction S are provided in two stages in the carrying direction F, as shown in FIG. The color of the ink used for the print heads in each stage, the number of these heads arranged, the order of arrangement, etc. may be the same or different for each stage depending on the image to be printed. Further, it is also possible to print again the area to be printed by the main scan of the print head of one stage by the print head of the next stage (complementary thinning printing is performed by the print head of each stage). However, it is also possible to perform overlapping printing) or to share the printing area and perform high-speed printing. Further, the number of stages of the print head is not limited to two, but may be one or three or more.

Further, in this example, the print head 1
As 100, an inkjet head, for example, a heating element that generates heat energy that causes film boiling in the ink as energy used to eject the ink,
A so-called bubble jet head is used. And
Used with the ink discharge port facing downward with respect to the cloth 1 that is to be transported in a substantially horizontal direction by the transport unit 100,
As a result, it is possible to eliminate the water head difference between the ejection ports, to make the ejection conditions uniform, and to form a good image, and to perform a uniform recovery process for all ejection ports.

Generally, the print head 1100 in such a printing apparatus is formed with thousands of ink ejection openings, and one or a plurality of such print heads 1100 are associated with each color of ink. It is equipped.

In FIG. 3, the capping means 1220.
Is for contacting the ejection port surface of each print head 1100 during non-printing operation to suppress the drying and mixing of foreign matter, or to remove the foreign matter. Specifically, during the non-printing operation, the print head 1100 moves to a position facing the capping unit 1220. And
The capping means 1220 is driven in the cap direction by the driving means 1210 and presses an elastic member or the like against the ejection port surface to perform capping.

The clogging preventing means 1231 receives the ejected ink when the print head 1100 performs the ejecting operation (preliminary ejecting operation) for uniformizing the ejecting condition by the ink refreshing. The clogging prevention means 1231 is provided at a portion facing the print head outside the print area by the print head, and a liquid receiving member for absorbing and receiving the pre-ejected ink is provided between the capping means 1220 and the print area. It is placed on the opposite side. A liquid holding member is provided in the liquid receiving member, and a sponge-like porous member or the like is used as its material.

Further, a wiping means (wiping blade) 70 capable of rubbing the ejection opening surface of the print head 1100 is arranged between the capping means 1220 and the print region, and the wiping means 70 is attached to the ejection opening surface by the rubbing. We try to wipe off water drops and dust.

The ink supply to the print head 1100 is performed by the sub tank of the ink supply unit 1130 and the ink replenishing unit 11 as will be described in detail later.
It is performed by a two-stage configuration of 40 main tanks. Ink is supplied from the supply unit 1130 to the print head 1100 by a flexible ink tube, and the guide member 1110 of the ink tube guides the movement associated with head scanning.

(3) Description of Configuration of Ink Supply System FIG. 4 is a schematic view showing an ink supply system according to an embodiment of the present invention.

The ink supply system of the present embodiment generally includes an inkjet head 1100, a sub-tank 401 that stores ink to be supplied to the head 1100, a main tank 301 that stores ink to be supplied to the sub-tank 401, and an ink tube that connects these elements. Etc.

Main tank 301 to sub tank 401
The ink is supplied to the tubes via the tubes 351, 352, 353 and 453. A pump 302 and a backflow preventive valve 303 are provided in the supply path formed of these tubes, and the sub tank 40 in this supply path is also provided.
A two-way valve 403 is provided near 1 to open and close the supply path. Further, in the vicinity of the main tank 301, the atmosphere communication tubes 355 and 356 are connected to the tube 351 via the joint 371, and this tube is connected to the communication valve 30.
It is opened and closed by 4.

Tubes 452, 554 and 552 are connected via a joint 471 in the middle of the supply path, and the supply path by these tubes reaches the ink jet head 1100. A tube 55 is provided between the sub tank 401 and the inkjet head 1100.
1, the air buffer 501 and the tube 451 are also connected by a supply path.

A tube 555, one end of which is connected to a predetermined liquid level of the air buffer 501, is connected to one side of a two-way valve 503, and the other of the valves 503 is a tube 55.
6, and the other end of the tube 556 is connected to the above-mentioned supply path composed of the tubes 452, 554 and the like. The tube 553 connected to the bottom of the air buffer 501 is connected to the tube 55 via the three-way valve 502.
2, 554 and the like are connected.

The sub-tank 401 is provided with a fan 402a for pressure-feeding ink via a tube 451 and the like, and a motor 402 for driving the fan 402a.
A drain 404 for draining is provided at a predetermined liquid level. A tube 354 is connected to the drain 404,
The tube 354 is guided to the main tank 301.

(4) Description of Normal Printing Operation of Ink Supply System FIG. 5 is a schematic diagram for explaining normal printing operation of the ink supply system of the embodiment shown in FIG.

In a normal printing operation, the negative pressure generated by the ink ejection from the print head 1100 causes the subtank 401 to the tube 451 and the air buffer 501.
And printhead 1100 via tube 551
Ink is supplied to. A part of the supplied ink is branched from the air buffer 501 into the tubes 553 and 552 and supplied to the print head 1100. In response to this ink supply, the print head 1100 ejects ink from its ejection port 1100a to fabric 1 (see FIG. 1, etc.).
To print. At this time, when bubbles are mixed in the ink, the bubbles are trapped when passing through the air buffer 501 and stay in the upper part of the air buffer. As a result, defective ejection of the print head 1100 caused by bubbles can be prevented.

(5) Description of bubble removing operation in the air buffer By the way, as described above, the accumulated bubbles gradually increase,
When it fills the air buffer 501, the tube 5
Since air is supplied to the print head 1100 via 51 or the like, it is necessary to regularly adjust the amount of air in the air buffer. The adjustment procedure is as follows.

That is, the ink in the ink supply path is pressurized by driving the pressure motor 402 of the sub tank 401. As a result, the ink is pressure-fed in the directions indicated by arrows A1, A2, A3, and A4 in the drawing through the same route as the above-described ink supply, and is ejected from the ejection port 1100a of the print head 1100.

In this state, as shown in FIG.
When 3 is opened to establish a communication state, the ink having the increased pressure guides the air excessively staying in the air buffer 501 to the sub tank 401 through the tubes 555, 556, the joint 571, and the tube 452. The air guided to the sub-tank 401 is discharged to the outside of the machine because the sub-tank 401 is in the atmosphere communicating state.

In this way, the air in the air buffer 501 is gradually discharged, but when the ink surface reaches the connection port 501a with the tube 555 by this discharging operation, the next ink is the tubes 555, 556 and the joint 571. , To the sub tank 401 via the tube 452. As a result, the air in the air buffer 501 can maintain a fixed amount of staying state.

(6) Description of Head Clogging Prevention Operation Further, from the state shown in FIG. 6, the adjustment valve 503 is closed and the pressure motor 402 is driven to pressurize the ink to prevent the clogging of the print head 1100. You can also take actions.

(7) Description of Ink Discharging Operation When Replacing Head Next, the ink discharging operation when replacing the print head in the configuration shown in FIG. 5 will be described.

When the print head is replaced, the ink joint 1102 is disconnected and the ink joint of a new print head is connected. At this time, the flow path 1101 of the new print head is filled with the storage filler. When the pressure motor 402 is driven in this state, the pressure of the ink in the ink supply path increases, and the arrow A in the figure
Ink is pressure-fed in the directions A1, A2, A3, and A4. As a result, ink flows into the flow path 1101 of the print head from both sides, and the filling agent filled in the liquid path can be discharged to the outside of the head through the ejection port 1100a. Therefore, if this ink pressurizing operation is performed for a certain period of time,
The filler in the print head 1100 is the sub tank 401.
All are replaced by ink supplied from.

(8) Description of simultaneous operation of bubble removal and ink discharge As shown in FIG. 7, the three-way valve 502 is switched to close the communication between the tube 552 and the tube 553, and the tube 55 is closed.
When the pressure motor 402 is driven in such a state that the No. 2 and the tube 554 are in communication with each other, a part of the ink in the print head 1100 is discharged to the outside of the head and stays in the ink flow path 1101 as in the conventional case. The air bubbles together with the ink are the tube 552, the three-way valve 502, the tube 5
After passing through 54 and 452 (in the directions of arrows A7 and A8 in the figure), they are guided to the sub tank 401.

(9) Description of Pressurization Control of Ink Supply System During the operations (4), (5), (6), and (7) above, as shown in FIGS. The ink in the tubes 551 and 552 leading to the ink is pressurized by the drive of the pressure motor 402 (hereinafter, referred to as “both sides pressure”), and the recovery operation of the print head 1100 is performed. Further, during the operation of (8), as shown in FIG. 7, the ink in one of the tubes 551, 552 is pressurized by the drive of the pressure motor 402, and the circulation path of the ink is changed. Once formed (hereinafter referred to as “circulation pressurization”), the print head 11
00 recovery operation will be performed. .

Such double-sided pressurization or cyclic pressurization is particularly suitable as a recovery method for the print head 1100 having thousands of ink ejection openings. That is, temporarily, by sucking ink from the ink ejection port of the print head 1100, the print head 11
In the case of trying to recover the so-called “00” by so-called suction recovery, it is difficult to apply a uniform suction force to all the ink discharge ports to suck the ink because there are many thousands of the ink discharge ports. A large scale device for generating force is also required. In this respect, in the recovery operation by pressurization as in the present embodiment, the recovery operation can be ensured by ejecting ink from each of the large number of ink ejection ports in the print head 1100, and 1 kg /
A sufficiently large pressing force of about cm ² can be generated with simple equipment.

In the present embodiment, in consideration of the presence of the bent portion 30A of the ink flow path and the filter portion 30B in the ink supply system as shown in FIG. Pressurization of ink by the pressure motor 402 is intermittently performed twice as shown in FIG. FIG. 9 (a)
Is a comparative example in the case where the recovery operation is performed by continuously pressurizing the ink as in the conventional case described above, and arrows A2, A4 and A7 in FIG. It is the ink flow direction, and the dotted line indicates the ink flow direction during cyclic pressurization. The method of pressurizing the ink is arbitrary, and for example, pressure may be intermittently introduced from a pressure accumulating section kept at a predetermined pressure to act on the ink supply path.

FIG. 10 shows the inside of the bent portion 30A when the recovery operation is performed by intermittently pressurizing the ink twice as shown in FIG. 9B.

FIG. 10A shows a first pressurization state in which the inside of the ink flow path 30 is pressed in the direction of arrow C, and the pressurizing operation is performed by the conventional continuous pressurization time T1 (see FIG. 9 ( See a))
By performing the operation at a shorter time T11, the bubble pool B2
It is difficult to do This is because a large stagnation of ink does not occur in the bent portion 30A and the bubble B1 is hard to be captured. FIG. 10B shows a state during the pressurization rest time T12 after that, the flow of ink is stopped, the compressed state of the bubbles in the air reservoir is released, and the bubbles are easily moved in the ink. FIG. 10C shows the state during the second pressurization time T13 after that, and the bubble B1 which has become in the easily moved state is reliably pushed out and removed by the ink flow. As a result, during the printing operation, there is no bubble B1 as shown in FIG. 10D, and proper printing can be performed without ink ejection failure.

FIG. 11 shows the inside of the filter unit 30B when the recovery operation is performed by intermittently pressurizing the ink twice as shown in FIG. 9B. The filter portion 30B of this example is provided in the flow path 30 for the ink supplied from the upper side to the lower side along the vertical direction, as in the above-described conventional example.

FIG. 11A shows a first pressurization state in which the inside of the ink flow path 30 is pressed in the direction of arrow C, and the pressurizing operation is performed by the conventional continuous pressurization time T1 (see FIG. 9 ( See a))
By performing the operation at a shorter time T11, the bubble pool B2
It is difficult to do This is because large stagnation of ink does not occur in the filter unit 30B and the bubbles B1 are hard to be captured. FIG. 11B shows the pressurization rest time T12 thereafter.
In the medium state, the flow of ink is stopped, and the compressed state of the air bubbles in the air reservoir is released, and the air bubbles easily move in the ink. FIG. 11C shows the state during the second pressurizing time T13 after that, and the bubble B1 that has become easily moved is reliably pushed out and removed by the ink flow. As a result, during the printing operation, there is no bubble B1 as shown in FIG. 11D, and proper printing can be performed without ink ejection failure.

Table 1 below shows specific experimental examples of the recovery operation by circulating pressurization as shown in FIG. In the case of circulation pressurization, the print head 1100 to the sub tank 401
Bubbles in the ink supply path will be removed together with the ink returned to. Here, the bent portion 30A and the filter portion 30B are configured as shown in FIG. 8, and ink is supplied to the print head 1100 through them. Bent part 30
The inner diameter of the ink flow path in A was 2.4 mm, and the pressure of the ink was 1 kg / cm ² .

[0053]

[Table 1]

In the experiment shown in Table 1 above, it is determined whether or not ink is not ejected due to air bubbles during printing after the recovery operation, and when the recovery operation is required after being left for 4 hours, the time required for the recovery operation is determined. It was determined whether the recovery operation was successful, that is, whether the ink was ejected to print after the recovery operation. In the case of the experimental example in the uppermost column of Table 1 above, since the pressurization pause time T12 is too short, it becomes a state close to continuous pressurization as in the past, and the compressed state of bubbles by the first pressurization is sufficient. It was not released and could not be completely removed. Also, in the case of the experimental example in the bottom column of Table 1 above, since the pressurization rest time T12 is too long, the bubbles return in the direction opposite to the head due to the buoyancy, which can be removed. There wasn't.

Table 2 below shows specific experimental examples of the recovery operation by pressurization on both sides as shown in FIG. In the case of pressurizing on both sides, bubbles discharged in the ink supply path are removed together with the ink discharged from the ejection port 1100a of the print head 1100.

[0056]

[Table 2]

In the experiment of Table 2 above, it is determined whether ink is ejected from the print head 1100 after the recovery operation to print, and when the recovery operation is performed after the replacement of the print head 1100, the new operation is performed. It was also determined whether or not the preservative filler in the print head 1100 was completely removed and replaced with ink, that is, whether the preservative filler removal performance was good or bad. In addition, in the experiment of Table 1 above, in order to move the bubbles in the ink flow path to at least the bent portion 30A by the first pressurization and then to discharge the bubbles from the print head 1100 by the second pressurization, The first pressurizing time T11 and the second pressurizing time T13 were made different. In this way, pressurizing time T11, T
By making 13 different, bubbles can be efficiently removed within a limited time.

Table 3 below shows a conventional example of FIG.
An example of an experiment in which a recovery operation by circulating pressurization similar to that in the case of Table 1 above is performed by continuously pressurizing for a predetermined time as shown in FIG.

[0059]

[Table 3]

(Embodiment 2) In this embodiment, as shown in FIG. 9C, the pressurizing motor 402 is controlled to intermittently pressurize the ink three times to perform the recovery operation. By intermittently pressurizing the ink three times in this manner,
0, the flow of ink in FIG. 11 repeatedly occurs and the bubbles vibrate, which facilitates movement away from the inner surface of the ink flow path. Therefore, the bubbles in the ink flow path are more surely removed.

Table 4 below shows a concrete experimental example of the recovery operation by circulating pressurization similar to the case of Table 1 of the above-mentioned Embodiment 1.

[0062]

[Table 4]

(Others) The number of times of pressurizing the ink intermittently during the recovery operation may be four times or more, and the pressurizing time and pressurizing pause time in that case can be set appropriately.

[0064]

As described above, according to the present invention, by intermittently pressurizing the ink supply path to perform the recovery operation of the ink jet head, bubbles that are likely to stay in a bent portion in the ink flow path are generated. It can be reliably removed. Further, since the recovery operation is performed by applying pressure, even for an inkjet head having a large number of ink ejection ports, such as an inkjet head in a textile printing apparatus, a sufficient pressure can be generated by simple equipment to ensure a reliable operation. It is possible to perform various recovery operations.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a print unit and a transport system of the inkjet recording apparatus of FIG.

FIG. 3 is a front view schematically showing the inkjet recording apparatus of FIG.

FIG. 4 is a schematic diagram showing a configuration of an ink supply system according to an embodiment of the present invention.

5 is a schematic diagram showing an ink supply system from a sub-tank to a print head in the ink supply system of FIG. 4, for explaining an ink operation during ink ejection.

6 is a schematic diagram for explaining an ink operation for liquid level adjustment of an air buffer in the ink supply system of FIG.

FIG. 7 is a schematic diagram for explaining an ink operation of removing air from a print head in the ink supply system of FIG.

FIG. 8 is a partially cutaway front view of a print head for explaining a part of the ink supply system of FIG.

FIG. 9 is an explanatory diagram of ink pressurizing operation timing of the recovery method according to the present invention.

FIG. 10 is an explanatory diagram of a situation in a bent portion of an ink flow path when a recovery method according to the present invention is performed.

FIG. 11 is an explanatory diagram of a situation in the filter unit when the recovery method according to the present invention is performed.

FIG. 12 is a diagram illustrating a situation in a bent portion of an ink flow path when a conventional recovery method is performed.

FIG. 13 is an explanatory diagram of a situation inside the filter unit when a conventional recovery method is performed.

[Explanation of symbols]

401 Sub-tank 402 Pressurizing motor 451, 452, 551, 552, 553, 554 Ink tube 502 3-way valve 503 Adjustment valve (2-way valve) 571 Joint 1100 Print head 1100a Ink ejection port 1101 Ink liquid chamber 1102 Ink joint

Claims (12)

[Claims] 1. An inkjet printing apparatus that uses an inkjet head for ejecting ink and ejects ink from the inkjet head onto a print medium to perform printing, and a supply unit that supplies ink to the inkjet head. A pressurizing unit capable of pressurizing the ink in the ink supply path between the head and the supply unit; and an intermittent operation of the ink in the ink supply path by controlling the pressurizing unit during the recovery operation of the inkjet head. And a control means for ejecting the ink in the inkjet head to the outside of the inkjet head. 2. The inkjet printing apparatus according to claim 1, further comprising a circulation path for returning the ink discharged to the outside of the inkjet head to the ink supply path. 3. The ink jet printing apparatus according to claim 1, wherein the control unit discharges ink from an ink ejection port of the ink jet head to the outside. 4. The control unit varies a plurality of pressurization times when intermittently pressurizing the ink in the ink supply path a plurality of times. The inkjet printing apparatus described in 1. 5. The control unit varies a plurality of pressurization pause times when intermittently pressurizing the ink in the ink supply path a plurality of times, according to any one of claims 1 to 4. An inkjet printing device according to claim 1. 6. The inkjet printing apparatus according to claim 1, wherein the inkjet head discharges ink for printing on a cloth. 7. The ink jet head according to claim 1, wherein the ink jet head uses thermal energy to generate bubbles in the ink, and the ink is ejected by the generation of the bubbles. The inkjet printing apparatus described. 8. A method for recovering the inkjet head in an inkjet printing apparatus, wherein an inkjet head for ejecting ink is used, and the ink is ejected from the inkjet head onto a print medium to perform printing. A method for recovering an ink jet head, characterized in that the ink in the ink jet head is discharged to the outside of the ink jet head by intermittently pressurizing the ink in the ink supply path for supplying the ink. 9. The method for recovering an inkjet head according to claim 8, wherein the ink discharged to the outside of the inkjet head is returned to the ink supply path. 10. The method for recovering an inkjet head according to claim 8, wherein the ink in the inkjet head is discharged to the outside from an ink ejection port of the inkjet head. 11. The inkjet head according to claim 8, wherein when the ink in the ink supply path is intermittently pressed a plurality of times, a plurality of pressurizing times are different. Recovery method. 12. The inkjet according to claim 8, wherein when the ink in the ink supply path is intermittently pressurized a plurality of times, a plurality of press rest periods are made different. How to recover the head.