JP2010221460A - Fluid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable use of an atmosphere opening valve without subjecting to constraint on a layout while enabling appropriate idle suction. <P>SOLUTION: A fluid in a jetting head is sucked by bringing a fluid receiving part into contact with jetting nozzles and actuating a suction pump while the atmosphere opening valve is kept closed. After sucking the fluid, the suction pump is stopped once and the atmosphere opening valve is opened, and thereafter, idle suction is carried out by actuating the suction pump again. The ink is sucked up to a position of the atmosphere opening valve when the suction pump is stopped after the fluid in the jetting head is sucked. However, when the atmosphere opening valve is prepared in the halfway of an atmosphere opening passage, the ink is prevented from immediately leaking even if the atmosphere opening valve is opened. The suction pump starts to return before the ink reaches an opening end of the atmosphere opening passage. Leakage of the ink at the time of idle suction can thus be avoided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for ejecting fluid from an ejection head.

A so-called inkjet printer prints an image by ejecting ink onto a print medium. Since the position and amount of ink ejected can be controlled with extremely high accuracy, a high-quality image can be printed. In addition, a fluid ejecting apparatus that forms various functional parts such as electrodes and sensors by ejecting a fluid containing various functional materials onto a substrate using this technique has been proposed.

In these ink jet printers or fluid ejecting apparatuses, a dedicated ejecting head is mounted so that fluid such as ink can be ejected appropriately, and the fluid is ejected from nozzles provided in the ejecting head. In addition, since the properties of the fluid in the ejection head change with time (such as increase in viscosity) and it is difficult to eject the fluid properly, in order to appropriately maintain the fluid properties, the following “ An operation called “cleaning” is performed.

First, the cap is brought into contact with the ejection head to seal the periphery of the ejection nozzle, and then a negative pressure is applied to the cap with a suction pump to forcibly suck out the fluid whose properties have changed in the ejection head from the ejection nozzle. Do it. The state in which the cap is brought into contact with the ejection head is called a “capping state”. When the fluid in the ejection head has been sucked, the suction pump is once stopped, and then the atmosphere release valve is opened so that the outside air in the cap can be introduced. The cap is provided with a tube (atmosphere release tube) whose one end opens into the cap and the other end communicates with the outside. The other end of the atmosphere release tube is sealed at the other end. An air release valve that can be opened and closed is provided. Normally, the other end of the atmosphere release tube is sealed with an atmosphere release valve. However, after the fluid is sucked out from the ejection head, the atmosphere release valve is opened. In this state, the suction pump is operated again. Then, the fluid in the cap is drawn by the pump and discharged, and at the same time, air flows in from the atmosphere release tube, so that all the fluid in the cap can be finally discharged. In addition, operating the suction pump with the air release valve opened is called “empty suction”. When all the fluid in the cap is discharged in this way, the “cleaning” is finished.

In addition, when the air release valve is opened for empty suction, the fluid in the cap may leak to the outside from the air release tube. As a countermeasure, the air release valve may be installed at a position higher than the cap ( Patent Document 1), a technique has been proposed in which the suction pump is operated immediately before opening the atmosphere release valve, and the atmosphere release valve is opened in a state where a fluid flow toward the suction pump is formed (patent). Reference 2).

JP 2007-050602 A JP 2008-213463 A

However, since the jet head exists above the cap, the technique described in Patent Document 1 described above provides an air release valve at a position higher than the cap while avoiding contact with the jet head. Therefore, there is a problem that layout restrictions are large. In the technique described in Patent Document 2, a large negative pressure is generated in the cap in order to operate the suction pump before the atmosphere release valve is opened. When the atmosphere release valve is opened, air flows in vigorously. Then, there is a problem that the inside of the cap is foamed, and if this foam adheres to the ejection nozzle, the fluid may not be ejected properly.

The present invention has been made in response to the above-mentioned problems of the conventional technology, and can perform idle suction appropriately without being restricted in layout or foaming in the cap. Aims to provide new technology.

In order to solve at least a part of the problems described above, the fluid ejecting apparatus of the present invention employs the following configuration. That is,
A fluid ejection device that ejects fluid from an ejection nozzle provided in an ejection head,
A recess for receiving fluid from the ejection nozzle is formed, and a fluid receiving portion that forms a closed space around the ejection nozzle by bringing the recess into contact with the ejection head;
A suction pump connected to the recess of the fluid receiving portion to apply a negative pressure in the recess;
An atmosphere opening passage which is a passage having one end opened in the recess of the fluid receiving portion and the other end opened to the atmosphere;
An atmosphere release valve for switching the atmosphere release passage between an open state and a closed state;
A fluid suction operation for sucking the fluid in the ejection head from the ejection nozzle by operating the suction pump in a state where the concave portion of the fluid receiving portion is brought into contact with the ejection head and the air release passage is closed. Fluid suction means to perform,
After the operation of the suction pump is stopped, the air suction passage is sucked in by introducing the outside air into the recess while switching the atmosphere open passage to an open state and operating the suction pump again. An empty suction means for performing
The gist is that the air release valve is an open valve provided in the middle of the air release passage.

In such a fluid ejection device of the present invention, after contacting the fluid receiving portion to the ejection nozzle,
The negative pressure is generated by the suction pump while the air release passage is closed, thereby sucking the fluid in the ejection head. Since the atmosphere release passage is closed by the atmosphere release valve, the pressure in the recess of the fluid receiving portion and the atmosphere release passage is reduced by the suction pump, and as a result, the fluid is sucked out from the injection nozzle. After the fluid is sucked, the suction pump is temporarily stopped to open the atmosphere release passage, and then the suction pump is operated again to perform the idle suction. Here, the air release valve for switching the air release passage to the open state or the closed state is provided in the middle of the air release passage.

When the suction pump is stopped after sucking the fluid in the ejection head with the suction pump, the ink in the recess is sucked to the position of the atmosphere release valve by the negative pressure in the atmosphere release passage. However, since the atmosphere release valve is provided in the middle of the atmosphere release passage, the ink that has been drawn into the passage passes through the atmosphere release valve by opening the atmosphere release valve (opening the atmosphere release passage). Even in this case, ink does not leak immediately from the end (open end) on the atmosphere side of the atmosphere release passage. Then, since the suction pump is operated and pulled back until the ink reaches the open end of the atmosphere opening passage, it is possible to prevent the ink from leaking during the idle suction.

Further, in such a fluid ejecting apparatus of the present invention, at the time of idle suction, it is assumed that the suction pump is operated after a predetermined fixed time has elapsed since the opening of the air release valve, and from the open end of the air release passage for a fixed time. It is good also as providing an air release valve in the position separated more than the predetermined distance decided according to.

It is considered that the speed at which the fluid travels in the atmosphere release passage is almost the same value unless the path of the atmosphere release passage is significantly changed. Therefore, in the idle suction operation, if the suction pump is operated after a lapse of a certain period of time after opening the atmosphere release valve, the distance that the ink travels through the atmosphere release passage can be estimated during that time. If an atmosphere release valve is provided at a position separated from the end of the atmosphere release passage on the atmosphere side by the distance estimated in this way, it is possible to easily prevent fluid from leaking out during idle suction. .

It is explanatory drawing which showed the rough structure of the fluid injection apparatus of a present Example using an inkjet printer as an example. It is explanatory drawing which shows the structure of the bottom face side of a head assembly. It is explanatory drawing which showed the detailed structure of the maintenance mechanism. It is explanatory drawing which shows the reason that an ink may leak outside in the case of an air suction in the structure which provided the air release valve in the edge part of the air release tube. It is explanatory drawing which showed a mode that the inkjet printer of a present Example performed idle suction.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Device configuration:
B. Maintenance mechanism structure:
C. Empty suction operation of this embodiment:

A. Device configuration :
FIG. 1 is an explanatory diagram showing a rough configuration of a fluid ejecting apparatus of this embodiment using a so-called ink jet printer as an example. As shown, inkjet printer 1
0 is a carriage 2 that forms ink dots on the print medium 2 while reciprocating in the main scanning direction.
0, a drive mechanism 30 that reciprocates the carriage 20, a platen roller 40 that feeds the print medium 2, and a maintenance mechanism 100 that performs maintenance so that printing can be performed normally. The carriage 20 is provided with an ink cartridge 26 containing ink, a carriage case 22 in which the ink cartridge 26 is mounted, a head assembly 24 mounted on the bottom side of the carriage case 22 (side facing the print medium 2), and the like. It has been. As will be described later, the head assembly 24 is provided with a plurality of ejecting heads for ejecting ink. By ejecting the ink in the ink cartridge 26 from the ejecting head to the printing medium 2 by an accurate amount, an image is formed. It is supposed to be printed.

The drive mechanism 30 that reciprocates the carriage 20 includes a timing belt connected to the carriage case 22, a step motor that drives the timing belt, and the carriage case 2.
In order to guide the two moving directions, it is composed of a guide rail or the like extending in the main scanning direction. In addition, the platen roller 40 that feeds the print medium 2 is driven by a drive motor or a gear mechanism (not shown), and can feed the print medium 2 by a predetermined amount in the sub-scanning direction.

The maintenance mechanism 100 is provided in a region called a home position outside the printing region, and is pressed against the bottom surface side of the head assembly 24 to form a sealed space with the ejection head, below the cap unit 120. The maintenance unit 130 provided at the position of FIG. 2 and the waste liquid tank 110 provided below the maintenance unit 130 are also included. When printing is not performed, the carriage 20 is moved to the home position, and the cap portion 120 is pressed against the bottom surface of the head assembly 24 to form a sealed space with the ejection head mounted on the head assembly 24. As will be described later, the ejection head has a small ejection nozzle for ejecting ink. By forming a sealed space by pressing the cap portion 120, the viscosity increases due to drying of the ink in the ejection head. Can be prevented.

However, even if the cap 120 is pressed to prevent the ink from drying, the ink properties change (especially the viscosity increases) due to a decrease in moisture and volatile components in the ink little by little over a long period of time. . Therefore, by pressing the cap unit 120 against the head assembly 24 and forming a sealed space with the ejection head, the suction pump built in the maintenance unit 130 is operated to apply a negative pressure to the sealed space. An operation (cleaning operation) of sucking out the ink inside the head assembly 24 from the ejection nozzle is performed. Further, the ink discharged by the cleaning operation is stored in the waste liquid tank 110.

FIG. 2 is an explanatory diagram showing the configuration of the bottom side of the head assembly 24. As shown in the drawing, a plurality of ejection heads 25 are provided on the bottom surface of the head assembly 24, and each ejection head 25 is provided with small ejection nozzles Nz that eject ink. Further, a predetermined number of these ejection heads 25 (two in the illustrated example) form one set, and each group of ejection nozzles Nz has a Y (yellow) color, an M (magenta) color, and a C ( Cyan) and K (black) inks are ejected.

B. Maintenance mechanism structure:
FIG. 3 is an explanatory view showing the detailed structure of the maintenance mechanism 100. As shown in the drawing, a rectangular recess 122 is provided on the upper surface side (the side facing the head assembly 24) of the cap portion 120, and ink discharged from the ejection head 25 during the cleaning operation is received by the recess 122. It is possible. In addition, a suction port 124 connected to a suction pump described later and an air intake 126 connected to an air release valve described later are provided on the bottom surface of the recess 122.

A suction pump 150 and an air release valve 140 are accommodated in the maintenance unit 130. The suction pump 150 is a tube type pump that sucks fluid by rotating a cam while crushing a part of the tube with a built-in cam. Recess 1
The suction port 124 and the suction pump 150 provided in 22 are connected by the suction tube 152, and the suction pump 150 and the waste liquid tank 110 are also connected by the suction tube 152. Therefore, by operating the suction pump 150,
The ink in the recess 122 can be sucked and discharged to the waste liquid tank 110.

An atmosphere release tube 142 is connected to the atmosphere intake 126 provided in the recess 122, and the other end side of the atmosphere release tube 142 is opened to the atmosphere. An air release valve 140 is provided in the middle of the air release tube 142. Therefore, if the atmosphere release valve 140 is opened, the atmosphere intake 126 in the recess 122 is connected to the outside atmosphere, and if the atmosphere release valve 140 is closed, the atmosphere intake 126 is connected to the outside atmosphere. It is possible to be in a blocked state. In the inkjet printer 10 of the present embodiment, since the atmosphere release valve 140 is provided in the middle of the atmosphere release tube 142 as described above, when the atmosphere release valve 140 is opened for empty suction, the ink is released. Will not leak to the outside. In the following, the reason why this is possible will be described. As a preparation, in the conventional structure in which the atmosphere release valve 140 is provided at the end of the atmosphere release tube 142, ink leaks to the outside during idle suction. Briefly explain why there are cases.

C. Empty suction operation of this embodiment:
FIG. 4 is an explanatory diagram showing the reason why ink may leak to the outside during idle suction in the conventional structure in which the atmosphere release valve is provided at the end of the atmosphere release tube 142. FIG. 4A shows a state in which the concave portion 122 of the cap portion 120 is made a sealed space by bringing the cap portion 120 into contact with the head assembly 24 prior to idle suction. The air release valve provided on the other end side of the air release tube 142 is closed. When the suction pump 150 is operated in this state, the pressure in the concave portion 122 decreases and eventually ink is sucked out from the ejection nozzle provided in the head assembly 24. At this time, the pressure in the air release tube 142 is also lowered together with the pressure in the recess 122.

FIG. 4B shows a state where the suction pump 150 is operated to suck out the ink in the head assembly 24. The ink in the head assembly 24 flows into the recess 122 through the fine ejection nozzle, and the ink that has flowed into the recess 122 is sucked by the suction pump 150. Since the flow path resistance is generated in the portion of the ejection nozzle, the pressure in the recess 122 on the downstream side of the ejection nozzle is substantially equal to the negative pressure generated by the suction pump 150, and the upstream side of the ejection nozzle is the ink. The pressure is determined by the structure of the cartridge 26 (approximately atmospheric pressure). In other words, ink is sucked out from the ejection nozzle at a flow rate determined by this pressure difference.

When the thickened ink in the head assembly 24 is sucked out in this way, the suction pump 150
To stop. As described above, since there is a pressure difference between the upstream side (ink cartridge 26 side) and the downstream side (inside the recess 122) of the ejection nozzle, the ink pump immediately stops when the suction pump 150 is stopped. The flow doesn't stop. Therefore, even after the suction pump 150 is stopped, the ink flows from the ejection nozzle into the recess 122 according to the remaining pressure difference, and the pressure in the recess 122 increases as the ink flows. Here, during the operation of the suction pump 150 as described above, since the inside of the atmosphere release tube 142 is at the same pressure as the recess 122, when the suction pump 150 is stopped and the pressure in the recess 122 rises, the recess The ink in 122 is drawn into the atmosphere release tube 142. FIG. 4C shows how ink is drawn into the atmosphere release tube 142 as the pressure in the recess 122 increases after the suction pump 150 is stopped.

Since the pressure in the atmosphere release tube 142 is the same as that up to the atmosphere release valve, in most cases, the ink is drawn to the portion of the atmosphere release valve. With the ink drawn up to the atmosphere release valve in this way, when opening the atmosphere release valve for empty suction, with the momentum of opening the valve,
As shown in FIG. 4D, a situation in which ink leaks to the outside occurs. In order to avoid such a situation, the air release valve is often provided at a position higher than the ink level in the recess 122. However, providing the air release valve at a position that does not contact the head assembly 24 or the carriage case 22 is not so much. It ’s not easy. On the other hand, in the inkjet printer 10 of the present embodiment, it is possible to avoid the occurrence of such a problem by adopting a structure in which an air release valve is provided in the middle of the air release tube 142. Hereinafter, this point will be described in detail.

FIG. 5 is an explanatory diagram showing a state in which the inkjet printer 10 of the present embodiment performs idle suction. In FIG. 5A, prior to the idle suction, the cap portion 120 is attached to the head assembly 24.
The state immediately after the ink suction is started by operating the suction pump 150 in contact with the ink is shown. As described above with reference to FIG. 3, the maintenance mechanism 100 of the present embodiment.
Then, an air release valve 140 is provided in the middle of the air release tube 142, and FIG.
At the stage shown in FIG. 4, the atmosphere release valve 140 is in a closed state. Therefore, the suction pump 15
As 0 is actuated and the pressure in the recess 122 decreases, the pressure in the atmosphere release tube 142 up to the atmosphere release valve 140 also decreases.

FIG. 5B shows a state where ink in the head assembly 24 is sucked out from the ejection nozzle. As described above with reference to FIG. 4, the downstream side of the injection nozzle (in the recess 122)
And a pressure difference between the upstream side of the injection nozzle and the flow rate corresponding to this pressure difference,
Ink is sucked out. At this stage, the portion of the atmosphere release tube 142 up to the atmosphere release valve 140 has the same negative pressure as that in the recess 122.

When the thickened ink in the head assembly 24 is sucked out, the suction pump 150 is stopped. As described above, even if the suction pump 150 is stopped, the recess 1
The ink flows into the ink 22 and the pressure in the recess 122 is restored accordingly. As the pressure in the recess 122 recovers, ink is drawn from the recess 122 into the atmosphere release tube 142. However, in the present embodiment, the air release valve 140 is provided in the middle of the air release tube 142, and naturally, the inside of the air release tube 142 has a negative pressure up to the air release valve 140. It is. Accordingly, the ink in the concave portion 122 is drawn only to a portion of the atmosphere release tube 142 where the atmosphere release valve 140 is provided. FIG. 5C shows a state in which ink is drawn up to a place where the air release valve 140 is provided in the middle of the air release tube 142 after the suction pump 150 is stopped.

From this state, after the atmosphere release valve 140 is opened, the suction pump 150 is operated to start empty suction. The air release valve 140 is provided in the middle of the air release tube 142. By opening the air release valve 140, even if the ink drawn into the air release tube 142 passes through the air release valve 140, the atmosphere release valve 140 is opened to the atmosphere. Since the open end of the tube 142 is ahead, ink does not leak immediately. If the suction pump 150 is operated until the ink reaches the open end of the atmosphere release tube 142, the ink in the atmosphere release tube 142 can be pulled back to the concave portion 122 again. By operating the suction pump 150 with the air release valve 140 opened as described above, the recess 1 is formed as shown in FIG.
It is possible to perform the idle suction for sucking the ink remaining in the recess 122 while introducing the atmosphere in the interior 22.

As described above, in the inkjet printer 10 of the present embodiment, by adopting a structure in which the atmosphere release valve 140 is provided in the middle of the atmosphere release tube 142, the open end on the atmosphere side of the atmosphere release tube 142 is recessed. Even when it is provided at a position lower than 122, it is possible to prevent ink from leaking from the open end. For this reason, since the mounting position of the air release valve 140 and the degree of freedom of piping of the air release tube 142 are greatly increased, the design of the ink jet printer 10 can be facilitated.

Further, as shown in FIG. 5D, if the distance L from the atmosphere release valve 140 to the atmosphere side open end of the atmosphere release tube 142 is set as follows, the atmosphere release valve 140 is set. And the degree of freedom of piping of the air release tube 142 are further increased, and the design of the inkjet printer 10 can be further facilitated. That is, during idle suction, the time from when the air release valve 140 is opened to when the suction pump 150 is activated is known in advance, and during this time, the distance that the ink travels through the air release tube 142 is determined. Check in advance. Then, the length L from the atmosphere release valve 140 to the open end to the atmosphere is set to a length that allows for a margin beyond the distance traveled by the ink. In this way, the ink does not leak from the open end of the air release tube 142 unless the height and direction of the open end of the air release tube 142 or the mounting position of the air release valve 140 are significantly different. Therefore, in practice, it is possible to freely set the piping of the atmosphere release tube 142 and the position of the atmosphere release valve 140 with little concern about ink leakage.

Although the ink jet printer 10 as the fluid ejecting apparatus of the present embodiment has been described above, the present invention is not limited to the above-described embodiment or modification, and may be implemented in various modes without departing from the gist thereof. Is possible.

The present invention can be used in a technique for ejecting a fluid such as ink onto a medium such as printing paper.

2 ... print medium, 10 ... inkjet printer, 20 ... carriage,
22 ... Carriage case 24 ... Head assembly 25 ... Jet head
26 ... Ink cartridge, 30 ... Drive mechanism, 40 ... Roller,
100 ... Maintenance mechanism 110 ... Waste liquid tank 120 ... Cap part,
122: Recess, 124 ... Suction port, 126 ... Air intake port, 140 ... Air release valve,
142 ... Air release tube, 150 ... Suction pump, 152 ... Suction tube

Claims (2)

A fluid ejection device that ejects fluid from an ejection nozzle provided in an ejection head,
A recess for receiving fluid from the ejection nozzle is formed, and a fluid receiving portion that forms a closed space around the ejection nozzle by bringing the recess into contact with the ejection head;
A suction pump connected to the recess of the fluid receiving portion to apply a negative pressure in the recess;
An atmosphere opening passage which is a passage having one end opened in the recess of the fluid receiving portion and the other end opened to the atmosphere;
An atmosphere release valve for switching the atmosphere release passage between an open state and a closed state;
A fluid suction operation for sucking the fluid in the ejection head from the ejection nozzle by operating the suction pump in a state where the concave portion of the fluid receiving portion is brought into contact with the ejection head and the air release passage is closed. Fluid suction means to perform,
After the operation of the suction pump is stopped, the suction pump is operated again in a state in which the atmosphere release passage is switched to an open state, thereby sucking the fluid in the recess while introducing the outside air into the recess. An empty suction means for performing a suction operation,
The fluid ejection device, wherein the atmosphere release valve is an release valve provided in the middle of the atmosphere release passage. The fluid ejection device according to claim 1,
The idle suction means is means for operating the suction pump after a predetermined time has elapsed since the atmosphere release passage is switched to an open state.
The fluid ejection device, wherein the atmosphere release valve is an release valve provided at a position separated from an end of the atmosphere release passage on the atmosphere side by a predetermined distance determined according to the predetermined time.

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