JP2012096502A - Liquid jet apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress transmission of pressure fluctuation of a liquid generated on an upstream side from a jet head to a jet nozzle of a liquid jet apparatus.SOLUTION: The liquid in a liquid housing container is made to flow in a first liquid passage. The first liquid passage includes a width-enlarged part 108 of which a width of a cross sectional area is enlarged downward. A filter 110 is arranged on a lower end of the width-enlarged part 108. The liquid passing through the filter 110 is supplied to the jet head 24 by a second liquid passage to jet from the jet nozzle. An air bubble accumulating chamber 112 for accumulating mixed air bubbles is arranged on the first liquid passage, wherein a bottom part of the air bubble accumulating chamber is opened on a wall surface of the width-enlarged part 108, and a ceiling of the air bubble accumulating chamber 112 is set in a position higher than an upper end of the width-enlarged part 108. Thereby, the air bubbles accumulated in the air bubble accumulating chamber 112 can be utilized for a damper, and the pressure fluctuation of the liquid transmitted from the upstream side of the first liquid passage is absorbed, enabling suppression of transmission of the pressure fluctuation of the liquid to the jet nozzle.

Description

  The present invention relates to a technique for ejecting liquid from an ejection nozzle provided in an ejection head.

As represented by so-called ink jet printers, liquid ejecting apparatuses that eject liquid from fine ejecting nozzles provided in an ejecting head are known. In this liquid ejecting apparatus,
A liquid such as ink to be ejected is stored in a dedicated container such as an ink cartridge, and the liquid is ejected by supplying the liquid from the dedicated container to the ejection head via the liquid passage.

Such a cartridge is configured to be detachable from the liquid ejecting apparatus so that the cartridge is replaced with a new one when the liquid in the interior is exhausted (for example, Patent Document 1).
When the cartridge is mounted, a liquid take-up needle communicating with the liquid passage is inserted into the liquid supply port of the cartridge, and the liquid in the cartridge is taken into the liquid passage.

JP 2007-216563 A

However, in the liquid ejecting apparatus employing such a cartridge system, there is a problem that a problem (so-called nozzle omission) may occur that the liquid is not ejected appropriately from the ejection nozzle immediately after the cartridge is replaced. This is because when the liquid intake needle is inserted into the liquid supply port of the cartridge, the pressure fluctuation (increase in pressure) occurs in the liquid as the volume of the liquid supply port changes (decreases). It originates in destroying the meniscus which the liquid surface has formed with the injection nozzle by transmitting to the injection nozzle through the liquid passage. Also,
The pressure fluctuation of the liquid generated on the upstream side of the ejecting head is caused by an impact when the adjacent cartridge is touched or the liquid ejecting device is dropped in the operation of replacing any of the plurality of cartridges. It also occurs when the relative position of the changes.

The present invention has been made to solve the above-described problems of the prior art,
An object of the present invention is to provide a technique capable of preventing nozzle omission by suppressing the pressure fluctuation of the liquid generated upstream of the ejection head from being transmitted to the ejection nozzle.

In order to solve at least a part of the problems described above, the liquid ejecting apparatus of the present invention employs the following configuration. That is, a liquid ejecting apparatus that supplies liquid contained in a liquid storage container to an ejection head and ejects the liquid from an ejection nozzle provided in the ejection head, and is a liquid that takes in the liquid in the liquid accommodation container An intake port, a first liquid passage in which a liquid taken in from the liquid intake port flows and a widened portion whose cross-sectional area widens downward, and a lower end of the widened portion are provided. A filter that removes foreign matter contained in the liquid, and a second liquid passage that guides the liquid that has passed through the filter to the ejection head, and the first liquid passage includes air bubbles mixed in the first liquid passage. The bubble storage chamber for storing air is provided with a bottom portion opened to the wall surface of the widened portion, and the ceiling of the bubble storage chamber is set at a position higher than the upper end of the widened portion. .

In such a liquid ejecting apparatus of the present invention, the liquid in the liquid storage container is taken in from the liquid intake and flows into the first liquid passage. In the first liquid passage, a widened portion whose cross-sectional area widens downward is formed, and a filter is provided at the lower end of the widened portion, so that foreign matters are removed when the liquid passes through the filter. Is done. At this time, although the filter is resistant to the flow of the liquid, the flow rate of the liquid passing through the filter can be secured by providing the widened portion on the upstream side of the filter. The liquid thus passing through the filter is supplied to the ejection head through the second liquid passage and ejected from the ejection nozzle provided in the ejection head. In the liquid ejecting apparatus according to the aspect of the invention, the first liquid passage is provided with a bubble storage chamber for storing the mixed bubbles, and the bubble storage chamber has a bottom portion that opens on the wall surface of the widened portion, and the bubble storage chamber. Is set at a position higher than the upper end of the widened portion.

In the liquid ejecting apparatus of the present invention having the above-described configuration, when bubbles are mixed into the first liquid passage,
The bubbles move to the widened portion along the liquid flow. Since the flow of the liquid becomes slow in the widened portion, the bubbles that have been swept up are lifted by buoyancy. At this time, bubbles that have floated enter the bubble storage chamber that opens to the wall surface of the widened portion, so that the bubbles accumulate on the ceiling of the bubble storage chamber. The bubbles accumulated in the bubble storage chamber in this manner can be used as a damper that absorbs the pressure fluctuation of the liquid generated on the upstream side of the first liquid passage. That is, when the pressure fluctuation of the liquid is transmitted through the first liquid passage and the pressure of the liquid in the widening portion and the bubble storage chamber increases, the bubble in the bubble storage chamber contracts to suppress a rapid pressure increase. In contrast, when the pressure of the liquid decreases, the bubble expands to suppress a sudden pressure decrease. In this way, since the pressure fluctuation of the liquid transmitted from the upstream side of the first liquid passage can be absorbed (relaxed) using the bubbles in the bubble storage chamber, the jet nozzle provided in the downstream jet head can be used. It is possible to suppress the transmission of the pressure fluctuation of the liquid. As a result, missing nozzles due to liquid pressure fluctuations (problems in which liquid is not properly ejected from the ejection nozzle)
Can be prevented.

In the liquid ejecting apparatus of the present invention, since the ceiling of the bubble storage chamber is set at a position higher than the upper end of the widened portion, the vicinity of the ceiling of the bubble storage chamber is from the flow of the liquid in the first liquid passage. It is a stagnation area that has come off (the liquid flow does not enter). For this reason, the bubbles accumulated on the ceiling of the bubble storage chamber do not ride on the liquid flow and flow to the downstream jet head, and the bubbles can be stably stored in the bubble storage chamber.

In the liquid ejecting apparatus of the present invention described above, a plurality of protrusions may be provided on the ceiling of the bubble storage chamber so that the bubbles that are lifted by buoyancy may be supported at a plurality of locations by point contact or line contact.

Since it is the contact surface between the bubble and the liquid that can directly absorb the pressure fluctuation of the liquid on the surface of the bubble, the contact area between the bubble and the liquid is used to absorb the pressure fluctuation of the liquid using the bubble. If the pressure is wide, it is possible to absorb the pressure fluctuation of the liquid quickly. Therefore, if a plurality of protrusions provided on the ceiling of the bubble storage chamber support the bubbles at a plurality of locations by point contact or line contact, the bubbles directly contact the surface of the bubble storage chamber (surface contact). ) Compared to the case, it is possible to ensure a wide contact area between the bubbles and the liquid. As a result, the pressure fluctuation of the liquid transmitted from the upstream side of the first liquid passage can be quickly absorbed by the bubbles in the bubble storage chamber.

In such a liquid ejecting apparatus of the present invention, an outside air intake for taking in outside air may be provided in the bubble storage chamber.

The mixing of bubbles into the first liquid passage is generated when bubbles enter from the liquid intake port or gas dissolved in the liquid is bubbled, but the amount is not constant. Therefore, if an outside air inlet is provided in the bubble storage chamber, it is possible to actively take in the outside air, so it is necessary to secure a sufficient amount of bubbles in the bubble storage chamber to absorb liquid pressure fluctuations. Is possible. As a result, it is possible to more reliably suppress the liquid pressure fluctuation from being transmitted to the ejection nozzle.

It is explanatory drawing which showed the rough structure of the liquid ejecting apparatus of a present Example using an inkjet printer as an example. FIG. 6 is an explanatory diagram illustrating a state where an ink cartridge is mounted on a carriage case. FIG. 4 is a cross-sectional view illustrating a configuration of an ink supply port provided in the ink cartridge. It is explanatory drawing which showed the structure of the ink intake needle | hook of a present Example. It is the flowchart which showed the flow of the bubble management process performed with the inkjet printer of a present Example. It is explanatory drawing which showed the structure of the tube pump mounted in the inkjet printer of a present Example. It is sectional drawing which showed the structure of the bubble storage chamber of a 1st modification. It is explanatory drawing which showed the structure for taking in and out air to a bubble storage chamber with the inkjet printer of a 2nd modification. It is explanatory drawing which showed the example which provided the guide part eccentrically with respect to the wide part of the ink taking-in needle. It is explanatory drawing which showed the example which has arrange | positioned the bubble storage chamber provided in the wide part of an ink taking-in needle on both sides with respect to the guidance part.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Device configuration:
A-1. Configuration of liquid ejector:
A-2. Ink take-up needle configuration:
B. Bubble management processing of this example:
C. Variations:
C-1. First modification:
C-2. Second modification:

A. Device configuration :
A-1. Configuration of liquid ejector:
FIG. 1 is an explanatory diagram showing a rough configuration of a liquid ejecting apparatus according to the present embodiment, using a so-called ink jet printer as an example. As shown, inkjet printer 1
0 is a carriage 20 that forms ink dots on the printing paper 2 as a printing medium while reciprocating in the main scanning direction, a drive mechanism 30 that reciprocates the carriage 20, and a paper feed for the printing paper 2. It comprises a platen roller 40 and a maintenance mechanism 50 that performs maintenance so that printing can be performed normally. The carriage 20 has an ink cartridge 26 containing ink, and a carriage case 22 in which the ink cartridge 26 is mounted.
Or the ejection head 2 mounted on the bottom side of the carriage case 22 (the side facing the printing paper 2).
4 etc. are provided. The ejection head 24 is formed with a plurality of ejection nozzles that eject ink. The ink in the ink cartridge 26 is guided to the ejection head 24 and ejected from the ejection nozzle toward the printing paper 2 by an accurate amount. By doing so, an image or the like is printed.

In the ink jet printer 10 of this embodiment, it is possible to print a color image using four types of inks of cyan, magenta, yellow, and black. The mounted ejection head 24 is provided with an ejection nozzle for each type of ink. An ink cartridge 26 is also provided for each type of ink, and ink is supplied from the corresponding ink cartridge 26 to each ejection nozzle. The ink cartridge 26 of this embodiment corresponds to a “liquid container” of the present invention.

The drive mechanism 30 for reciprocating the carriage 20 includes a guide rail 38 extending in the main scanning direction, a timing belt 32 having a plurality of teeth formed therein, and a timing belt 32.
The drive pulley 34 meshes with the tooth profile of the above, the step motor 36 for driving the drive pulley 34, and the like. A part of the timing belt 32 is fixed to the carriage case 22, and the carriage case 22 can be moved along the guide rail 38 by driving the timing belt 32. Further, since the timing belt 32 and the drive pulley 34 are engaged with each other by a tooth shape, when the drive pulley 34 is driven by the step motor 36, the carriage case 22 can be moved with high accuracy according to the drive amount. .

The platen roller 40 that feeds the printing paper 2 is driven by a drive motor or a gear mechanism (not shown) and can feed the printing paper 2 by a predetermined amount in the sub-scanning direction.

The maintenance mechanism 50 is provided in a region called a home position outside the printing region, and includes a cap 52, a suction pump 54 provided at a position below the cap 52, and a waste liquid tank provided further below the cap 52. 56 or the like. The cap 52 is
It can be moved in the vertical direction by an elevating mechanism (not shown), and while the inkjet printer 10 is not printing an image or the like, the carriage 20 is moved to the home position and the cap 52 is raised. Then, the closed space is formed so that the cap 52 is pressed against the bottom surface side of the ejection head 24 and covers the ejection nozzle, so that the ink in the ejection head 24 can be prevented from drying. In addition, a suction pump 54 is connected to the cap 52 via a suction tube (not shown). By operating the suction pump 54 with the cap 52 pressed against the bottom surface of the ejection head 24, the ejection head 24 is operated. It is also possible to suck out deteriorated ink (such as dried and thickened ink) and discharge it to the waste liquid tank 56 (so-called cleaning).

Furthermore, a control unit 60 that controls the entire operation of the inkjet printer 10 is mounted on the back side of the inkjet printer 10. The operation of reciprocating the carriage 20, the operation of feeding the printing paper 2, the operation of ejecting ink from the ejection nozzles, the operation of driving the maintenance mechanism 50 to enable normal printing, etc. are all performed by the control unit 60. Is controlled by.

FIG. 2 is an explanatory view showing a state in which the ink cartridge 26 is mounted on the carriage case 22. As shown in the drawing, the carriage case 22 is provided with a recess 23 for mounting the ink cartridge 26 from above, and the bottom surface of the recess 23 receives ink for taking ink from the ink cartridge 26. The insertion needle 100 is erected for each ink cartridge 26. An ink supply port 70 is provided at the bottom of the ink cartridge 26.
When the ink cartridge 26 is mounted on the carriage case 22,
The ink supply port 70 provided in the ink cartridge 26 is fitted to the position of the ink take-in needle 100 provided in the carriage case 22 so as to push the ink cartridge 26 downward. Then, the ink take-in needle 100 is inserted into the ink supply port 70, and the ink in the ink cartridge 26 can be taken into the ink take-in needle 100.

FIG. 3 is a cross-sectional view showing the configuration of the ink supply port 70 provided in the ink cartridge 26. FIG. 3 shows a state where the ink take-in needle 100 is inserted into the ink supply port 70. As shown in the drawing, the ink supply port 70 includes a sealing valve 74 and a sealing valve 74.
A spring 76 or the like that presses the ink toward the opening side (the lower side in the drawing) of the ink supply port 70 is provided. When the ink intake needle 100 is not inserted into the ink supply port 70, the sealing valve 74 is pushed down by the force of the spring 76 and the opening of the ink supply port 70 is closed. When the ink take-in needle 100 is inserted into the ink supply port 70, the tip of the ink take-in needle 100 pushes up the sealing valve 74 against the force of the spring 76, as shown in FIG. , The opening of the ink supply port 70 is opened, and the inserted ink take-in needle 100
Ink is taken into the ink take-in needle 100 through an ink take-in port 102 provided near the tip of the ink take-in.

A rubber seal member 72 is provided along the inner wall of the opening of the ink supply port 70. When the ink take-in needle 100 is inserted into the ink supply port 70, the seal member 72 is provided.
Is in close contact with the outer surface of the ink take-in needle 100 to prevent ink from leaking out.

Here, when the ink cartridge 26 is mounted on the carriage case 22, the volume of the ink supply port 70 changes (decreases) because the ink intake needle 100 is inserted into the ink supply port 70 as described above. Accordingly, pressure fluctuation (increase in pressure) occurs in the ink in the ink supply port 70. Such pressure fluctuation is not only caused when the ink cartridge 26 is mounted on the carriage case 22, but also when the ink cartridge 26 is replaced, the adjacent ink cartridge 26 is touched, or the inkjet printer 10 is dropped while moving. This also occurs when the relative position of the ink cartridge 26 and the carriage case 22 changes due to the impact. When such pressure fluctuation is transmitted to the ejection nozzle of the ejection head 24 through the ink intake needle 100, the meniscus formed on the ink surface of the ejection nozzle is destroyed, and as a result, the ink is appropriately ejected from the ejection nozzle. Unsatisfactory printing (so-called nozzle missing) occurs. Therefore, in the ink jet printer 10 of the present embodiment, the ink intake needle 100 having the following configuration is employed in order to suppress the pressure fluctuation of the ink from being transmitted to the ejection nozzle.

A-2. Ink take-up needle configuration:
FIG. 4 is an explanatory diagram showing the configuration of the ink take-in needle 100 of the present embodiment. First, FIG.
) Is a perspective view showing an appearance of the ink take-in needle 100. As shown in the drawing, the ink take-in needle 100 has an upper step portion formed in a cylindrical shape and a lower step portion formed in a conical shape, and ink is applied to a pointed tip of the upper step portion. Multiple ink inlets 10 to be taken in
2 is open. Further, a bubble storage chamber 112 protrudes from the lower stage, and as will be described in detail later, bubbles (air) mixed in the ink take-in needle 100 can be stored in the bubble storage chamber 112. It is possible.

FIG. 4B is a cross-sectional view of the ink take-in needle 100 cut along a vertical plane passing through the tip of the ink take-in needle 100 and the center of the bubble storage chamber 112. As shown in the drawing, an inflow passage 1 into which ink taken in from the ink take-in port 102 flows into the ink take-in needle 100.
04 is provided, and a filter 110 for removing foreign substances contained in the ink is provided at the downstream end of the inflow passage 104. The inflow passage 104 includes a guide portion 106 whose cross-sectional area does not change and a widened portion 108 whose cross-sectional area widens toward the downstream side (downward in the drawing). The filter 110 is made of fine particles so as to remove foreign substances that clog the injection nozzle and the fine passage to the injection nozzle, so that the filter 110 makes it difficult for ink to flow (the flow resistance is reduced). However, the flow rate of ink passing through the filter 110 can be ensured by providing the widened portion 108 to widen the cross-sectional area. The ink that has passed through the filter 110 passes through the carriage case 22.
It is supplied to the ejection head 24 through a supply passage 28 provided in the inside. The ink intake port 102 of this embodiment corresponds to the “liquid intake port” of the present invention, and the inflow passage 10 of this embodiment.
4 corresponds to the “first liquid passage” of the present invention. Further, the supply passage 28 of this embodiment corresponds to a “second liquid passage” of the present invention.

Furthermore, as described above, the ink intake needle 100 of this embodiment is provided with the bubble storage chamber 112 for storing bubbles (air) mixed in the inflow passage 104. As shown in the figure, the bubble storage chamber 112 has a bottom portion that opens to the wall surface of the widened portion 108, and
The ceiling (the surface constituting the upper end side of the bubble storage chamber 112) is set at a position higher than the upper end of the widened portion 108.

The mixing of bubbles into the inflow passage 104 occurs when air enters from the ink intake port 102 when the ink intake needle 100 is inserted into the ink supply port 70 or air that has been dissolved in the ink is bubbled. To do. The bubbles in the inflow passage 104 move to the widened portion 108 on the downstream side along the ink flow. Since the ink flow is slow in the widened portion 108, the bubble that has been swept away rises by buoyancy. At this time, the air bubbles that have risen form the widened portion 10.
By entering the bubble storage chamber 112 that opens to the wall surface 8, bubbles accumulate on the ceiling of the bubble storage chamber 112. Further, since the ceiling of the bubble storage chamber 112 is provided so as to be higher than the upper end of the widened portion 108, it is a stagnation region that deviates from the ink flow (streamline). Therefore, the bubbles accumulated on the ceiling of the bubble storage chamber 112 do not ride on the ink flow, and the outflow of bubbles from the bubble storage chamber 112 can be suppressed.

As described above, in the ink jet printer 10 according to the present embodiment, the bubble storage chamber 112 communicating with the widened portion 108 of the inflow passage 104 is provided, and the bubbles are stored by storing the bubbles in the bubble storage chamber 112. Since the bubbles function as a damper, it is possible to suppress the pressure fluctuation of the ink generated on the upstream side of the inflow passage 104 from being transmitted to the ejection nozzle. In other words, the ink pressure fluctuation is transmitted through the inflow passage 104, and the widened portion 108 and the bubble storage chamber 1.
When the pressure of the ink in the ink 12 increases, the air bubbles in the air bubble storage chamber 112 contract (compress), thereby suppressing the increase in pressure, and conversely, the pressure of the ink in the widened portion 108. When the air pressure decreases, the air bubbles in the air bubble storage chamber 112 expand, thereby suppressing the pressure decrease. In this way, the bubbles in the bubble storage chamber 112 are used as dampers to absorb (relax) ink pressure fluctuations transmitted from the upstream side of the inflow passage 104 to the widened portion 108.
Therefore, it is possible to suppress the ink pressure fluctuation from being transmitted to the ejection nozzles on the downstream side.

Note that the larger the bubble in the bubble storage chamber 112, the larger the pressure fluctuation that can be absorbed (Boyle's law). However, as described above, the ink take-in needle 100 is mounted on the carriage case 22, and the volume of the bubble storage chamber 112 for storing bubbles is limited. The meniscus formed on the ink surface of the ejection nozzle tends to be destroyed when a pressure of about 4 kPa or more is applied. Therefore, if the ink pressure fluctuation is made smaller than this, nozzle omission can be prevented. As an example, 16 m for an ink take-in needle 100 having a volume of 77 mm ³
Experimental results have been obtained that if air bubbles of m ³ or more are stored, ink pressure fluctuations generated when the ink cartridge 26 is mounted on the carriage case 22 can be absorbed, and nozzle omission can be prevented. Therefore, in this case, a bubble storage chamber 112 that can store bubbles of about 16 mm ³ may be provided.

Here, since the amount of air entering from the ink intake port 102 when the ink intake needle 100 is inserted into the ink supply port 70 and the amount of air that has melted into the ink bubbled are not constant, the bubble storage chamber If there are too few bubbles (air) accumulated in 112, ink pressure fluctuations may not be sufficiently absorbed. On the other hand, when there are too many bubbles (air), the bubbles that protrude from the bubble storage chamber 112 flow downstream and are supplied to the ejection head 24, so that the ink is appropriately ejected from the ejection nozzles. It will disappear.

In view of these points, in the ink jet printer 10 of this embodiment, the bubble storage chamber 112 is used.
A communication hole 114 is provided in the ceiling, and air can be taken into the bubble storage chamber 112 from the communication hole 114, and conversely, air in the bubble storage chamber 112 can be extracted. The communication hole 114 of this embodiment corresponds to the “outside air inlet” of the present invention. As will be described in detail later, in the inkjet printer 10 of the present embodiment, a tube pump is connected to the communication hole 114 via a connection tube 116, and air is supplied to the bubble storage chamber 112 by driving the tube pump. It can be put in and out. Moreover, in the inkjet printer 10 of the present embodiment, the following bubble management process is performed, and the bubble storage chamber 112 is performed.
It is designed to manage the bubbles inside.

B. Bubble management processing of this example:
FIG. 5 is a flowchart showing the flow of the bubble management process performed by the inkjet printer 10 of the present embodiment. This process is executed by the control unit 60 when the power of the inkjet printer 10 is turned on.

As shown in the figure, in the bubble management process, first, the inkjet printer 10 is used.
Determines whether to start printing (step S100). As described above, the control unit 60
Since the overall operation of the inkjet printer 10 is controlled, the timing for starting printing can be determined. If printing is not started (step S1
00: no), the determination in step S100 is repeated, and the start of printing is monitored.

On the other hand, when printing is started (step S100: yes), the tube pump connected to the communication hole 114 of the bubble storage chamber 112 via the connection tube 116 is driven in the suction direction, so that the inside of the bubble storage chamber 112 is reached. Bubbles (air) are discharged (step S102). As described above, the ink pressure fluctuation generated on the upstream side of the inflow passage 104 is caused by the ink cartridge 26.
This is likely to occur when printing is not performed, such as when the printer is replaced or when the inkjet printer 10 is dropped during movement. In other words, since it is difficult for such ink pressure fluctuation to occur during printing, it is less necessary to store bubbles in the bubble storage chamber 112 in order to absorb ink pressure fluctuation than when printing is not performed. . In the unlikely event that air bubbles flow downstream and are supplied to the ejection head 24 during printing, the ink is not ejected properly from the ejection nozzles, resulting in poor printing. Therefore, in the inkjet printer 10 of the present embodiment, when the printing is started, the bubbles in the bubble storage chamber 112 are sucked and discharged.

Here, the structure of the tube pump of the present embodiment connected to the communication hole 114 of the bubble storage chamber 112 will be briefly described. FIG. 6 is an explanatory view showing the structure of the tube pump 150 mounted on the ink jet printer 10 of this embodiment. As shown in the figure, in the tube pump 150, a part of the tube 154 connected to the connection tube 116 is accommodated in an arc shape along the inner wall of the housing 152 in a cylindrical housing 152. It has a structure. In addition, a rotating disk 156 is provided inside the housing 152, and a roller 158 is rotatably supported by the rotating disk 156 in the guide groove 160. The guide groove 160 is close to the outer periphery of the rotating disk 156 on one end side,
The other end is formed so as to be away from the outer periphery of the rotating disk 156.

The tube pump 150 having such a structure operates as follows. First, when a motor (not shown) is operated to rotate the rotating disk 156 in the suction direction (the direction indicated by the arrow in the drawing), the roller 158 moves to one end side of the guide groove 160 and is shown in FIG. As described above, the tube 154 is squeezed (closed) between the roller 158 and the inner wall of the housing 152 because it protrudes greatly from the outer periphery of the rotating disk 156. In this state, when the rotating disk 156 is rotated in the suction direction and the roller 158 is moved along the tube 154,
Since the closed portion of the tube 154 also moves, the fluid (air, ink, etc.) in the tube 154 is sequentially pushed out and transferred downstream. In addition, after the roller 158 passes, the closed portion of the tube 154 tries to return to its original shape by the restoring force of the tube, so that a negative pressure is generated in the tube 154 and the fluid is sucked from the upstream. be able to. On the other hand, when the rotating disk 156 is rotated in the release direction (the direction opposite to the suction direction), the roller 1
Since 58 moves to the other end side of the guide groove 160 and moves away from the outer periphery of the rotating disk 156, the tube 154 is released from the closed state and is in an open state (communication state).

In step S102 of the bubble management process shown in FIG. 5, the tube pump 150 is driven in the suction direction to make the connection tube 116 have a negative pressure, whereby the bubbles in the bubble storage chamber 112 can be extracted. In the inkjet printer 10 of the present embodiment, a bubble detection sensor (not shown) for detecting bubbles in the bubble storage chamber 112 is provided, and the tube pump 150 is stopped when the bubbles in the bubble storage chamber 112 are discharged. (Step S10
4). In the present embodiment, the bubble discharge sensor detects the discharge of bubbles, but the present invention is not limited to this. For discharging the fluid (air and ink) corresponding to the volume of the bubble storage chamber 112. The required time (discharge time) may be obtained in advance, and the tube pump 150 may be stopped when the discharge time has elapsed. In this case, the ink in the bubble storage chamber 112 is discharged together with the surrounding ink.

When the bubbles in the bubble storage chamber 112 are discharged in this way, it is subsequently determined whether or not to end printing (step S106). The control unit 60 that controls the overall operation of the ink jet printer 10 can determine the timing for ending printing, as with the start of printing.
If printing is still in progress (step S106: no), step S106 is performed.
This determination is repeated until the end of printing is monitored.

On the other hand, when the printing is finished (step S106: yes), the tube pump 150 is driven in the release direction to be in an open state (step S108). As previously mentioned,
When printing is not being performed, ink pressure fluctuations may occur on the upstream side of the inflow passage 104 due to replacement of the ink cartridge 26 or dropping when the inkjet printer 10 is moved. 10, when the printing is finished, bubbles for absorbing such pressure fluctuations of the ink are stored in the bubble storage chamber 112. As described above with reference to FIG. 6, when the tube pump 150 is driven in the release direction, the blockage of the tube 154 in the tube pump 150 is released.
The bubble storage chamber 112 is opened to the atmosphere. During printing, as ink is ejected from the ejection nozzles of the ejection head 24, the ejected ink is drawn into the ejection head 24, so negative pressure is generated in the inflow passage 104 and the bubble storage chamber 112. It has become. Therefore, air is introduced into the bubble storage chamber 112 by opening the tube pump 150 when printing is finished.

When a predetermined amount of air for absorbing ink pressure fluctuations is taken into the bubble storage chamber 112, the tube pump 150 is driven in the suction direction to close the tube 154 (step S110). ). In this embodiment, the bubble detection sensor detects that the air in the bubble storage chamber 112 has reached a predetermined amount and closes the tube pump 150. However, the present invention is not limited to this, and the bubble storage chamber 112 is not limited thereto. The time required for taking in a predetermined amount of air (take-in time) may be obtained in advance, and the tube pump 150 may be closed when the take-in time has elapsed.

When a predetermined amount of air is thus taken into the bubble storage chamber 112, the process returns to the beginning of the bubble management process and waits until printing is started again (step S100). When printing is started, the tube pump 150 is moved in the suction direction. To discharge the bubbles in the bubble storage chamber 112 (step S102).

As described above, in the ink jet printer 10 of the present embodiment, the bubble storage chamber 112 is provided in the ink intake needle 100 so as to communicate with the inflow passage 104. The bubble storage chamber 112 is provided at a position above the widened portion 108 of the inflow passage 104 with the bottom opened to the wall surface of the widened portion 108. Since the ink flow is slow in the widened portion 108, the widened portion 1
The bubbles that have flowed up to 08 are lifted by buoyancy. At this time, the bubbles that have been lifted enter the bubble storage chamber 112, and the bubbles accumulate on the ceiling of the bubble storage chamber 112. Since the air bubbles accumulated in the air bubble storage chamber 112 function as a damper that absorbs the ink pressure fluctuation generated on the upstream side of the inflow passage 104, the ink pressure fluctuation is transmitted to the ejection nozzle of the downstream ejection head 24. Can be suppressed.

Although these bubbles (air) are effective in absorbing ink pressure fluctuations, if they flow downstream and are supplied to the ejection head 24, the ink is not properly ejected from the ejection nozzles, resulting in poor printing. Will occur. In the inkjet printer 10 of the present embodiment, since the ceiling of the bubble storage chamber 112 is set at a position higher than the upper end of the widened portion 108,
The upper part (near the ceiling) of the bubble storage chamber 112 is a stagnation region where the flow of ink does not enter. For this reason, the bubbles accumulated on the ceiling of the bubble storage chamber 112 do not move on the ink flow, and the bubbles can be prevented from flowing to the downstream ejection head 24.

In addition, in the inkjet printer 10 of the present embodiment, the communication hole 114 is provided in the ceiling of the bubble storage chamber 112, and air can be taken into the bubble storage chamber 112 from the communication hole 114. As a result, a sufficient damper effect of bubbles (air) in the bubble storage chamber 112 can be obtained, so that the pressure fluctuation of the ink generated on the upstream side of the inflow passage 104 is more reliably transmitted to the ejection nozzle. Can be suppressed. That is, when the ink cartridge 26 is replaced, air enters from the ink intake port 102 of the ink intake needle 100 or air that has been dissolved in the ink bubbles into the inflow passage 104. The amount is not constant, and if there are too few bubbles, ink pressure fluctuations may not be sufficiently absorbed. Therefore, if air can be taken in from the communication hole 114 provided in the bubble storage chamber 112, it is possible to secure an amount of air that can absorb ink pressure fluctuation by actively taking in air. As a result, it is possible to more reliably suppress the ink pressure fluctuation from being transmitted to the ejection nozzle.

Further, in the ink jet printer 10 according to the present embodiment, it is possible to extract bubbles in the bubble storage chamber 112 from the communication hole 114 provided in the bubble storage chamber 112. For this reason,
When air bubbles of a predetermined amount (a necessary amount for obtaining a damper effect) or more are mixed in the inflow passage 104, the air bubbles are extracted from the communication holes 114 of the air bubble storage chamber 112, thereby generating the air bubble storage chamber 1.
The bubbles in 12 can be kept at an appropriate amount, and as a result, the possibility of bubbles flowing to the downstream ejection head 24 can be reduced. In addition, if bubbles can be extracted from the communication hole 114 of the bubble storage chamber 112, the bubbles can be discharged without wasting ink unlike the case where the bubbles are discharged together with a large amount of ink by performing the above-described cleaning operation or the like. Can be discharged.

Furthermore, in the inkjet printer 10 of the present embodiment, paying attention to the fact that the ink pressure fluctuation on the upstream side of the inflow passage 104 is more likely to occur when printing is not performed than when printing, whether or not printing is in progress. Accordingly, bubbles are taken in and out of the bubble storage chamber 112. Thereby, when printing is not performed, the bubble damper effect can be obtained by incorporating bubbles, so that it is possible to suppress the ink pressure fluctuation from being transmitted to the ejection nozzle. On the other hand, during printing in which ink pressure fluctuation is less likely to occur than when printing is not performed, the possibility of bubbles flowing to the downstream ejection head 24 can be further reduced by extracting the bubbles.

C. Modified example:
There are several variations of the inkjet printer 10 of the present embodiment described above. Hereinafter, these modified examples will be described. In the description of the modification,
Constituent parts similar to those of the above-described embodiment are denoted by the same reference numerals as those of the above-described embodiment,
Detailed description thereof is omitted.

C-1. First modification:
As described above, when the ink pressure fluctuation is absorbed using the air bubbles accumulated in the air bubble storage chamber 112, if the contact area between the air bubbles and the ink is widened, the ink pressure fluctuation can be quickly absorbed. . Therefore, in the ink jet printer 10 of the first modified example, the bubble storage chamber 112 having the following configuration is employed in order to increase the contact area between the bubbles and the ink.

FIG. 7 is a cross-sectional view showing the configuration of the bubble storage chamber 112 of the first modification. As shown in FIG. 7A, a plurality of ribs 118 project from the ceiling of the bubble storage chamber 112 of the first modification. When the bubbles in the bubble storage chamber 112 are lifted by buoyancy, they are supported at a plurality of locations by line contact with the tips of the ribs 118, so that the bubbles are smaller than when the ribs 118 are not provided on the ceiling of the bubble storage chamber 112. The area in contact with the ceiling of the bubble storage chamber 112 can be reduced. Note that the rib 118 of the first modification corresponds to a “projection” of the present invention.

For comparison, FIG. 7B shows a state in which bubbles are accumulated in the bubble storage chamber 112 where the rib 118 is not provided. In this case, the air bubbles that are lifted directly come into contact (surface contact) with the ceiling of the bubble storage chamber 112. Therefore, the portion that can absorb the pressure fluctuation of the ink on the surface of the bubble is limited to the portion that is not in contact with the ceiling of the bubble storage chamber 112, that is, the lower portion that is in contact with the ink. Note that the arrows in FIG. 7 schematically show how bubbles absorb the increase in ink pressure.

On the other hand, as shown in FIG. 7A, the bubbles are supported by the tips of the plurality of ribs 118,
If the area where the bubbles are in contact with the ceiling of the bubble storage chamber 112 is reduced, the contact area between the bubbles and the ink is secured to that extent, so that the pressure fluctuation of the ink is not only on the lower side but also on the upper side. Absorbable. As a result, a rapid ink pressure fluctuation can be quickly absorbed by the bubbles in the bubble storage chamber 112.

In the first modification described above, a plurality of ribs 118 are provided on the ceiling of the bubble storage chamber 112,
Although the bubbles are supported at a plurality of locations by line contact, a plurality of small protrusions may be provided instead of the ribs 118 to support the bubbles at a plurality of locations by point contact. As described above, when the bubbles are supported by the point contact, it is possible to secure a wide contact area between the bubbles and the ink as compared with the surface contact.

C-2. Second modification:
In the above-described embodiment, air is taken into and out of the bubble storage chamber 112 by the tube pump 150.
It was supposed to be done using. However, the configuration for taking air in and out is not limited to this. Hereinafter, a second modified example in which air is taken in and out of the bubble storage chamber 112 with a configuration different from the above-described embodiment will be described.

FIG. 8 is an explanatory diagram showing a configuration for taking air into and out of the bubble storage chamber 112 by the ink jet printer 10 of the second modified example. As shown in the drawing, in the ink jet printer 10 of the second modification, the communication hole 1 of the bubble storage chamber 112 is connected via the connection tube 116.
14 is connected to a cylinder 170. A piston 172 is provided in the cylinder 170 so as to be able to reciprocate. The piston 172 is connected to an actuator (not shown) via a connecting rod 174.

According to such a configuration, when the actuator is operated to move the piston 172 to the bubble storage chamber 112 side (left side in the figure), the air in the cylinder 170 is pushed out and injected into the bubble storage chamber 112. it can. On the other hand, when the actuator is operated in the reverse direction and the piston 172 is moved to the actuator side (right side in the figure), the cylinder 170 has a negative pressure, so that the bubbles in the bubble storage chamber 112 can be extracted.

As described above, also in the ink jet printer 10 of the second modified example, the bubble storage chamber 1
By reciprocating the piston 172 in the cylinder 170 connected to the twelve communication holes 114, air can be taken in and out of the bubble storage chamber 112 as in the above-described embodiment. Therefore, by actively taking air into the bubble storage chamber 112, it is possible to secure an amount of bubbles that can absorb ink pressure fluctuations. Further, when there are too many bubbles in the bubble storage chamber 112 or when it is less necessary to store the bubbles, it is possible to suppress the bubbles from flowing to the downstream ejection head 24 by extracting the bubbles from the bubble storage chamber 112. .

Although various embodiments have been described above, the present invention is not limited to all the above embodiments, and can be implemented in various modes without departing from the scope of the invention.

For example, in the inkjet printer 10 of the above-described embodiment, air is taken in and out of the bubble storage chamber 112 depending on whether printing is in progress. However, it is also possible to keep the bubbles accumulated without extracting the bubbles from the bubble storage chamber 112 during printing. Even during printing, ink pressure fluctuation does not necessarily occur on the upstream side of the inflow passage 104, and if ink pressure fluctuation is transmitted to the ejection nozzles of the ejection head 24, it affects the amount of ink ejected. appear. Therefore, if air bubbles are accumulated in the air bubble storage chamber 112 even during printing, it is possible to prevent the ink pressure fluctuation from being transmitted to the ejection nozzles and to prevent defective printing. Also in this case, when the number of bubbles in the bubble storage chamber 112 is small, the communication hole 11 of the bubble storage chamber 112 is used.
By taking in air from 4, it is possible to secure an amount of bubbles that can absorb the pressure fluctuation of the ink. In addition, the air in the bubble storage chamber 112 tends to gradually increase due to air bubbles dissolved in the ink. Therefore, when a predetermined amount or more of bubbles are accumulated in the bubble storage chamber 112, by extracting the bubbles from the bubble storage chamber 112,
The amount of bubbles can be appropriately maintained so that the bubbles do not flow out of the bubble storage chamber 112, and as a result, the bubbles can be prevented from flowing to the downstream ejection head 24.

Further, the guide portion 106 of the ink take-in needle 100 may be provided eccentrically instead of the center of the widened portion 108. FIG. 9 is an explanatory view showing the ink take-in needle 100 in which the guiding portion 106 is eccentric with respect to the widened portion 108. FIG. 9A shows a plan view of the ink take-in needle 100. The hatched portion in FIG. 9A represents the upper surface of the bubble storage chamber 112. FIG. 9B shows the tip of the ink take-in needle 100 and the bubble storage chamber 112.
Sectional drawing which cut | disconnected the ink intake needle | hook 100 by the vertical plane which passes through the center of this is shown. In the example shown in FIG. 9, the widened portion 108 is formed in an oval shape (oval shape) instead of a perfect circular cone shape, and the guide portion 106 is provided eccentric to the widened portion 108 in the longitudinal direction. It has been. In this way, by providing the bubble storage chamber 112 on the side opposite to the side on which the guide portion 106 is eccentric, it is possible to secure a wide space for the bubble storage chamber 112, so that more bubbles can be stored. It becomes possible to leave. As a result, it is possible to more reliably suppress the ink pressure fluctuation from being transmitted to the ejection nozzle.

Further, the bubble storage chamber 112 provided in the widened portion 108 of the ink take-in needle 100 is provided with the guide portion 106.
However, it is not limited to one side, and may be provided on both sides as shown in FIG. In this case, the upper portions of the two bubble storage chambers 112 may be connected by the connecting passage 120. As described above, if the bubble storage chambers 112 are dispersed, it is possible to easily enter the bubble storage chamber 112 when bubbles moving on the ink flow and moving to the widening portion 108 are lifted by buoyancy.

10 ... inkjet printer, 20 ... carriage,
22 ... Carriage case, 24 ... Ejecting head, 26 ... Ink cartridge,
70 ... Ink supply port, 100 ... Ink intake needle, 102 ... Ink intake port,
104: Inflow passage, 106: Guide part, 108: Widening part,
110 ... Filter, 112 ... Bubble storage chamber, 114 ... Communication hole,
116 ... Connection tube, 150 ... Tube pump

Claims (3)

A liquid ejecting apparatus that ejects the liquid from an ejecting nozzle provided in the ejecting head by supplying the liquid accommodated in the liquid container to the ejecting head,
A liquid inlet for taking in the liquid in the liquid container;
A first liquid passage formed with a widened portion in which a liquid taken in from the liquid intake port flows in and a cross-sectional area is widened downward;
A filter provided at a lower end of the widened portion to remove foreign substances contained in the liquid;
A second liquid passage for guiding the liquid that has passed through the filter to the ejection head,
In the first liquid passage, a bubble storage chamber for storing bubbles mixed in the first liquid passage is provided with a bottom opening to the wall surface of the widened portion,
The liquid ejecting apparatus, wherein a ceiling of the bubble storage chamber is set at a position higher than an upper end of the widened portion. The liquid ejecting apparatus according to claim 1,
A liquid ejecting apparatus according to claim 1, wherein a plurality of protrusions are provided on a ceiling of the bubble storage chamber to support bubbles that are lifted by buoyancy at a plurality of locations by point contact or line contact. The liquid ejecting apparatus according to claim 1 or 2,
A liquid ejecting apparatus, wherein the bubble storage chamber is provided with an outside air inlet for taking in outside air.

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