JP2012196816A - Liquid discharging apparatus - Google Patents

Abstract

The present invention provides a liquid ejecting apparatus having a relatively simple structure and thereby suppressing an increase in cost.
A liquid storage section that stores liquid I, an ejection head that ejects liquid I, a supply path TB that supplies liquid I from the liquid storage section to the ejection head, and a middle of the supply path TB. A degassing tank 50 provided at a position higher than the liquid storage unit 6 and the ejection head 110, an exhaust pipe 54 provided in the canopy 50 c of the degassing tank 50, and an exhaust pipe 54. A liquid ejecting apparatus including a check valve 55.
[Selection] Figure 3

Description

  The present invention relates to a liquid ejecting apparatus.

  2. Description of the Related Art Conventionally, an ink jet printer (hereinafter referred to as “printer”) is widely known as a liquid ejecting apparatus that ejects ink droplets from a nozzle of an ink jet head onto a recording paper (medium). In such a printer, ink cartridges or ink tanks (liquid storage units) that store ink are temporarily opened to the atmosphere or constantly opened to the atmosphere, so that bubbles are inevitably mixed into the ink. . However, when air bubbles are mixed in the ink (liquid) ejected in this way, the air bubbles flow into the nozzles of the ink jet head, thereby causing clogging of the nozzles and causing ejection failure.

  Against this background, Patent Document 1 proposes a configuration in which a deaeration system is provided in an ink supply path using an external vacuum. That is, in this Patent Document 1, the functional liquid that constitutes at least a part of the functional liquid flow path that supplies the functional liquid from the functional liquid supply source to the ink jet type functional liquid droplet ejection head and that is passed through the functional liquid. A degassing tube for removing gas, which constitutes the functional liquid flow path, an inner tube made of a gas permeable material, an outer tube covering the inner tube with a degassing space, and the outer A deaeration tube provided with a vacuum suction port provided in the tube and communicating with the deaeration space has been proposed.

JP 2010-210989 A

However, the degassing tube has a complicated structure, and there is a concern that the cost of a printer (liquid ejecting apparatus) including the degassing tube may increase.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid ejecting apparatus that has a relatively simple structure, thereby suppressing an increase in cost.

  The liquid ejecting apparatus of the present invention includes a liquid storing unit that stores a liquid, an ejecting head that ejects the liquid, a supply path that supplies the liquid from the liquid storing unit to the ejecting head, and a middle of the supplying path. A deaeration tank provided at a position higher than the liquid storage part and the ejection head, an exhaust pipe provided in a canopy part of the deaeration tank, and a check valve provided in the exhaust pipe It is characterized by having.

  According to this liquid ejecting apparatus, since the deaeration tank is arranged at a position relatively higher than the liquid storage part, the water head difference corresponding to the height with respect to the liquid storage part and the inside of the deaeration tank become negative pressure. Therefore, for example, even if air bubbles are mixed in the liquid in the liquid reservoir due to being opened to the atmosphere, the liquid passes through the supply path into the deaeration tank and is exposed to a negative pressure. The liquid easily deaerates, and the mixed bubbles are removed from the liquid and collected on the canopy side of the deaeration tank. The gas (air) accumulated on the canopy side is discharged from the deaeration tank by the exhaust pipe provided in the canopy portion and the check valve provided in the exhaust pipe.

In the liquid ejecting apparatus, the deaeration tank may include a connection port with the supply path on the storage unit side and a supply path of the ejection head in a state where only the upper side that is the canopy side is open. It is preferable that a partition wall is provided to be separated from the connection port.
In this way, when the liquid flows into the deaeration tank through the supply path on the reservoir side and then flows out from the deaeration tank through the connection port on the ejection head side, the liquid gets over the partition wall. Pass through the side close to the canopy. Then, since a negative pressure air layer composed of bubbles removed from the liquid is formed on the canopy side, the bubbles in the liquid easily diffuse into the air layer from the liquid and are removed from the liquid. Become so.

In the liquid ejecting apparatus, it is preferable that the exhaust pipe is connected to a suction pump provided in a capping mechanism in a maintenance mechanism.
In this way, it is possible to remove bubbles in the liquid without providing a new suction pump and thus without complicating the device structure.

1 is a diagram illustrating a configuration of a printer according to an embodiment. It is sectional drawing which shows the internal structure of a head. It is a schematic block diagram of an ink supply mechanism. FIG. 2 is a block diagram illustrating an electrical configuration of a printer.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing, each member has a different scale so that each member has a size that can be recognized on the drawing.

  FIG. 1 is a diagram illustrating a schematic configuration of an embodiment of a liquid ejecting apparatus according to the invention. In FIG. 1, reference numeral 100 denotes an ink jet printer as a liquid ejecting apparatus. The printer 100 is a device that performs a printing process while conveying a sheet-like medium M such as paper or a plastic sheet. The printer 100 includes a housing 101, an ink jet mechanism 102 that ejects ink onto the medium M, an ink supply mechanism 103 that supplies ink to the ink jet mechanism 102, a transport mechanism 104 that transports the medium M, and an ink jet mechanism 102. A maintenance mechanism 105 that performs maintenance operations and a control device 106 that controls these mechanisms are provided.

  Hereinafter, the XYZ rectangular coordinate system is set, and the positional relationship of each component will be described with reference to the XYZ rectangular coordinate system as appropriate. In this embodiment, the liquid ejection direction is the Z direction, the head moving direction is the Y direction, and the direction orthogonal to the Z direction and the Y direction is the X direction.

  The casing 101 is formed so that the Y direction is the longitudinal direction. The casing 101 is provided with each part of the ink jet mechanism 102, the ink supply mechanism 103, the transport mechanism 104, the maintenance mechanism 105, and the control device 106. The casing 101 is provided with a platen 13. The platen 13 is a support member that supports the medium M, and is disposed at the center in the X direction in the housing 101. The platen 13 has a flat surface (not shown) oriented in the + Z direction, and this flat surface is used as a support surface that supports the medium M.

  The transport mechanism 104 includes a transport roller, a motor that drives the transport roller, and the like. The transport mechanism 104 transports the medium M from the −X side of the housing 101 into the housing 101 and discharges the medium M from the + X side of the housing 101 to the outside of the housing 101. Further, the transport mechanism 104 transports the medium M so that the medium M passes over the platen 13 inside the housing 101. Further, the transport mechanism 104 is controlled by a control device 106 such as transport timing and transport amount.

The ink jet mechanism 102 includes a head (ejection head) 110 that ejects ink (liquid) toward the medium M sent onto the platen 13, and a head moving mechanism 107 that holds and moves the head 110. Yes.
The head 110 includes a head case 18, a flow path unit 19, and an actuator unit 20 as shown in FIG.

The head case 18 is formed in a box shape so as to have a hollow portion. A flow path unit 19 is joined to the lower end surface of the head case 18. The actuator unit 20 is accommodated in a hollow portion 37 formed inside the head case 18. A case channel 25 is provided inside the head case 18 so as to penetrate the height direction.
The upper end of the case flow path 25 is connected to the sub tank 2 shown in FIG. The lower end of the case channel 25 communicates with the common liquid chamber 44 in the channel unit 19. With such a configuration, ink from the ink cartridge 6 (liquid storage unit) shown in FIG. 1 is supplied to the common liquid chamber 44 side through the case flow path 25 shown in FIG.

  The actuator unit 20 supplies a plurality of piezoelectric vibrators 38 arranged in a comb shape, a fixed plate 39 that holds the piezoelectric vibrator 38, and a drive signal from the control device 106 to the piezoelectric vibrator 38. Flexible cable 40. The piezoelectric vibrator 38 is fixed so that its lower end protrudes from the lower end surface of the fixed plate 39 in FIG. A surface of the fixing plate 39 different from the surface on which the piezoelectric vibrator 38 is fixed is bonded to the inner wall surface of the case that defines the hollow portion 37.

  The flow path unit 19 includes a vibration plate 41, a flow path substrate 42, and a nozzle plate 43. The vibration plate 41, the flow path substrate 42, and the nozzle plate 43 are bonded in a stacked state. The flow path unit 19 constitutes a series of liquid flow paths from the common liquid chamber 44 to the nozzle 47 formed in the nozzle plate 43 through the liquid supply port 45 and the pressure chamber 46. The pressure chamber 46 is formed such that the direction perpendicular to the arrangement direction (nozzle row direction) of the nozzles 47 is the longitudinal direction.

  The nozzle plate 43 forms the ejection surface 110a of the head 110, and two nozzle rows (not shown) in which a large number of nozzles 47 are aligned are arranged in a zigzag manner, for example.

  As shown in FIG. 1, the head moving mechanism 107 has a carriage 4, and the head 110 is fixed to the carriage 4. The carriage 4 is in contact with a guide shaft 8 that extends in the longitudinal direction (Y direction) of the housing 101. The head 110 and the carriage 4 are arranged above the platen 13 (+ Z direction).

In addition to the carriage 4, the head moving mechanism 107 includes a pulse motor 9, a driving pulley 10 that is rotationally driven by the pulse motor 9, and the driving pulley 10 that is provided on the opposite side in the width direction of the housing 101. A pulley 11, and a timing belt 12 that is stretched between the drive pulley 10 and the idle pulley 11 and connected to the carriage 4 are provided.
The carriage 4 is connected to a timing belt 12 and is provided so as to be movable in the Y direction as the timing belt 12 rotates. When moving in the Y direction, the carriage 4 is guided by a guide shaft 8.

  The ink supply mechanism 103 is for supplying ink to the head 110. In this embodiment, the ink supply mechanism 103 includes four ink cartridges (liquid storage units) 6 corresponding to four types of inks of black, magenta, yellow, and cyan. ing. The printer 100 according to the present embodiment has a configuration (off-carriage type) in which these ink cartridges 6 are accommodated at positions different from the head 110.

  That is, the ink supply mechanism 103 of the present embodiment includes an ink cartridge 6 that stores ink, a supply tube TB for supplying ink from the ink cartridge 6 to the head 110, and the supply tube TB as shown in FIG. , And a deaeration tank 50 provided in the middle. The ink in the supply tube TB is transferred to the supply tube TB toward the head 110 between the ink cartridge 6 and the degassing tank 50 or between the degassing tank 50 and the head 110. A liquid feed pump (not shown) is provided.

  The ink cartridge 6 is provided with a vent hole 6a in its top cover, and is thus always open to the atmosphere during use. Therefore, the ink I stored inside is mixed with air in the atmosphere as air bubbles by being placed under atmospheric pressure. In this embodiment, the ink cartridge 6 is arranged and fixed at substantially the same height as the head 110. Therefore, there is almost no water head difference between the ink cartridge 6 and the head 110. In this embodiment, since there is no water head difference as described above, a liquid feed pump is provided in the supply tube TB as described above, and the ink I in the ink cartridge 6 is pressure-fed and supplied to the head 110 by this liquid feed pump. ing.

  The ink cartridge 6 may be arranged at a position higher than the head 110 to generate a water head difference, and the ink I in the ink cartridge 6 may be supplied to the head 110 by the water head difference. In that case, it can be set as the structure which does not provide a liquid feeding pump in supply tube TB.

  The deaeration tank 50 has a first connection port 50a connected to the supply tube TB on the ink cartridge 6 side and a second connection port 50b connected to the supply tube TB on the head 110 side on the bottom side of the side wall. is doing. The first connection port 50a and the second connection port 50b are provided at positions facing each other. The deaeration tank 50 is connected and arranged in the middle of the supply tube TB by the first connection port 50a and the second connection port 50b.

  The deaeration tank 50 is disposed and fixed at a position higher than the ink cartridge 6 and the head 110 by holding means (not shown). Therefore, by being disposed relatively higher than the ink cartridge 110, the inside of the deaeration tank 50 has a water head difference and a negative pressure corresponding to the height relative to the ink cartridge 110. The height (height difference) of the deaeration tank 50 with respect to the ink cartridge 6 is, for example, about 20 cm to 30 cm. That is, the liquid level of the ink I in the degassing tank 50 is about 20 cm to 30 cm higher than the liquid level in the ink cartridge 6. As a result, a water head difference of about 2 kPa to 3 kPa occurs between these liquid levels.

  In the deaeration tank 50, a partition wall 51 is provided between the first connection port 50a and the second connection port 50b. The partition wall 51 is arranged so as to divide the inside of the deaeration tank 50 into the first connection port 50a side and the second connection port 50b side. The partition wall 51 has an opening 52 only on the canopy part 50c side of the deaeration tank 50. Is forming. With such a configuration, the first connection port 50 a side and the second connection port 50 b side are communicated only by the opening 52 on the partition wall 51 in the deaeration tank 50. That is, the ink I that has flowed from the first connection port 50a passes over the partition wall 51, passes through the opening 52, and flows out from the second connection port 50b.

  The distance between the upper end of the partition wall 51 and the lower surface of the canopy 50c, that is, the width of the opening 52 in the height direction is, for example, about 1 cm to 3 cm. Note that air bubbles mixed in the ink I are removed from the ink I, as will be described later, on the upper side of the deaeration tank 50, that is, the canopy 50c side, thereby forming a negative pressure air layer 53. . Therefore, the liquid level of the ink I is lowered by the height of the negative pressure air layer 53. However, the height of the negative pressure air layer 53 is as small as, for example, about 5 mm or less, and further, as described later, this height is held at a predetermined height or less. The surface never falls below the upper end of the partition wall 51.

  An exhaust pipe 54 for discharging the air forming the negative pressure air layer 53 is connected to the canopy portion 50 c of the deaeration tank 50. A suction pump 113 of a capping mechanism 112 described later is connected to the exhaust pipe 54 at the other end on the side opposite to the one end connected to the deaeration tank 50. Further, a check valve 55 is provided in the path of the exhaust pipe 54. The check valve 55 is a known valve configured to flow air only from one end side to the other end side without flowing air from the other end side of the exhaust pipe 54 to one end side.

  That is, the negative pressure air layer 53 has a negative pressure corresponding to the water head difference as compared with the atmospheric pressure, as will be described later, but air on the atmosphere side is brought into the negative pressure air layer 53 side by the check valve 55. Inflow is prevented. Further, the air forming the negative pressure air layer 53 can be discharged by being sucked by the suction pump 113.

  The deaeration tank 50 is provided with a sensor 56 that detects the liquid level of the ink I. As the sensor 56, various conventionally known sensors can be used as long as they can detect the liquid level of the ink I. For example, an optical sensor in which a light emitting element and a light receiving element are combined, a float type liquid level gauge, or the like is used. In the present embodiment, it is assumed that an optical sensor is used.

  As shown in FIG. 1, the maintenance mechanism 105 is disposed at the home position of the head 110. This home position is set in an area outside the area where printing is performed on the medium M. In the present embodiment, the home position is set on the −Y side of the platen 13. The home position is a place where the head 110 waits when the printer 100 is turned off, when recording is not performed for a long time, or when maintenance work is performed.

  The maintenance mechanism 105 includes a wiping mechanism 111 that wipes the ejection surface 110a of the head 110 (the outer surface of the nozzle plate 43), a capping mechanism 112 that covers the ejection surface 110a with a cap (not shown), and a nozzle 47 of the head 110. And a flushing mechanism 115 for performing a flushing process for ejecting ink.

  The wiping mechanism 111 includes a wiping member (not shown) that can face the ejection surface 110a of the head 110. By wiping the ejection surface 110a with the wiping member, ink remaining on the ejection surface 110a and the ejection surface Foreign matter adhering to 110a is removed.

  The capping mechanism 112 includes a cap that covers the ejection surface 110a and a suction pump 113 connected to the cap. With such a configuration, the capping mechanism 112 operates the suction pump 113 in a state where the ejection surface 110a of the head 110 is covered with the cap, and sucks the space on the ejection surface 110a, thereby capping the ink in the nozzle 47. The nozzle 47 is filled with new ink while being discharged to the side.

  The suction pump 113 is also connected to the exhaust pipe 54 of the deaeration tank 50 described above via a switching valve (not shown). As a result, the suction pump 113 can perform both the discharge of the ink in the nozzle 47 of the head 43 and the discharge of the air in the negative pressure air layer 53 in the deaeration tank 50 by switching the switching valve. Yes. The waste ink discharged from the head 110 to the cap side is collected by, for example, a waste liquid collection mechanism (not shown).

  The flushing mechanism 115 includes, for example, a flushing box (not shown), and the ink is thickened by forcibly ejecting (discharging) ink from the nozzles 47 of the head 110 into the flushing box. It is designed to prevent clogging.

  FIG. 4 is a block diagram illustrating an electrical configuration of the printer 100. The printer 100 includes a control device 106 that controls the operation of the entire printer 100. The control device 106 is connected to an input device IP for inputting various information related to the operation of the printer 100, a storage device MR storing various information related to the operation of the printer 100, and the like. 107, a maintenance mechanism 105, and the like are connected. The control device 106 includes a control unit 106a. The control unit 106a reads the sensor 56 provided in the deaeration tank 50, operates the suction pump 113, and switches the suction by the suction pump 113. The switching operation of the switching valve to be performed is controlled, and the wiping mechanism 111 and the capping mechanism 112 of the maintenance mechanism 105 are controlled.

Next, the operation of the printer 100 configured as described above will be described.
As a maintenance operation (initial operation) prior to the ejection (ejection) operation of the ink I onto the medium M, first, capping is performed by the capping mechanism 112 and further suction operation is performed by the suction pump 113. Further, when the suction operation is performed in this manner, the ejection surface 110a is wetted with the ink I, and therefore, the ink I remaining on the ejection surface 110a is wiped off and removed by the wiping mechanism 111. In addition to the suction operation by the capping mechanism 112 and the wiping operation by the wiping mechanism 111, the flushing mechanism 115 appropriately performs the flushing operation.

  When such a maintenance operation is completed, the head 110 is ejected (discharged) in the same manner as in the past, and printing is performed on the medium M. At that time, in the ink supply mechanism 103 shown in FIG. 3, the ink I stored in the ink cartridge 6 is sent to the deaeration tank 50 by a liquid feed pump (not shown) with the ejection operation of the head 110. Then, after the ink I sent to the deaeration tank 50 flows into the deaeration tank 50, it passes over the partition wall 51 and flows toward the second connection port 50b, and then passes through the sub tank 2 shown in FIG. Into the head 110. Then, the nozzle 47 discharges (injects).

  At that time, the ink I was easily degassed and mixed in the degassing tank 50 by being exposed to a negative pressure based on a water head difference between the degassing tank 50 and the ink cartridge 6. Air bubbles are discharged from ink I. Then, bubbles (air) discharged and removed from the ink I accumulate on the canopy 50c side of the degassing tank 50, and form a negative pressure air layer 53 on the canopy 50c side. However, the amount of bubbles mixed in the ink I is very small. Therefore, even if the ejection operation by the head 110 is performed for a long time, the volume of the negative pressure air layer 53 formed by the accumulation of the bubbles is not so large. Don't be. For example, as described above, the height of the negative pressure air layer 53 is about 5 mm or less.

  In addition, a partition wall 51 is provided in the deaeration tank 50, and the first connection port 50a and the second connection port 50b to which the supply tube TB is connected are arranged on the bottom side of the deaeration tank 50. Therefore, when the ink I passes through the deaeration tank 50, it must overcome the partition wall 51. At that time, since the ink I approaches the negative pressure air layer 53 by getting over the partition wall 51, the bubbles in the ink I easily diffuse from the ink I into the negative pressure air layer 53. Therefore, the bubbles in the ink I are easily extracted from the ink I and removed.

  In addition, when used for a long time, naturally the height (layer height) of the negative-pressure air layer 53 also becomes gradually high (thick). Therefore, the liquid level height of the ink I is detected by the sensor 56, and thereby the height (layer height) of the negative pressure air layer 53 is detected. When the height (layer height) of the negative pressure air layer 53 reaches a predetermined height set in advance, for example, 5 mm to 10 mm, the suction pump 113 is operated by the control unit 106a to perform a suction operation. Thus, the air forming the negative pressure air layer 53 is sucked and the air is removed from the deaeration tank 50. Thereafter, the operation of the suction pump 113 is stopped.

  In the printer 100 having such a configuration, since the deaeration tank 50 is disposed at a position relatively higher than the ink cartridge 6, the water head difference corresponding to the height relative to the ink cartridge 6, the inside of the deaeration tank 50. Can be made negative pressure. Therefore, even if air bubbles are mixed in the ink I in the ink cartridge 6 because it is open to the atmosphere, the ink I is introduced into the deaeration tank 50 and exposed to a negative pressure, thereby exposing the ink I. Can be easily degassed, and the mixed bubbles can be removed from the ink I. Therefore, clogging of the nozzle 47 caused by bubbles can be prevented by a relatively simple structure, and this can suppress an increase in cost.

  The bubbles removed from the ink I are collected on the canopy 50c side of the deaeration tank 50. The gas (air) collected on the canopy 50c side is an exhaust pipe 54 provided on the canopy 50c. And the check valve 55 can be used to discharge from the deaeration tank 50.

  Further, since the partition wall 51 is provided in the deaeration tank 50, when the ink I flows into the deaeration tank 50 and then flows out through the second connection port 50b, the canopy is overcome by overpassing the partition wall 51. It passes through the side closer to the portion 50c. Accordingly, since the negative pressure air layer 53 composed of the bubbles removed from the ink I is formed on the canopy 50c side, the bubbles in the ink I are easily diffused into the negative pressure air layer 53, and the ink I It will be removed from inside.

  Further, since the exhaust pipe 54 is connected to the suction pump 113 provided in the capping mechanism 112 in the maintenance mechanism 105, a new suction pump is provided to exhaust the negative pressure air layer 53 in the deaeration tank 50. There is no need, and therefore, the bubbles in the ink I can be removed without complicating the device structure.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
For example, in the above embodiment, the ink cartridge 6 is used as the liquid storage portion in the present invention, and the ink cartridge 6 is disposed inside the housing 101 as shown in FIG. 1, but the present invention is not limited to this. For example, the present invention can be applied to a printer that holds and fixes an ink tank (not shown) as a liquid storage unit on the outside of the housing 101 by a fixing means such as a fixing holder. That is, when the ink tank is held and fixed to the outside of the casing 101, the ink tank is disposed at a position relatively lower than the degassing dunk 50 provided in the casing 101. Similar to the embodiment, the ink I stored in the ink tank can be easily deaerated in the deaeration tank 50.

  For the deaeration tank 50, in order to further promote the deaeration of the ink I here, an ultrasonic vibrator is provided to apply ultrasonic vibration to the ink I, or a heater is provided to remove the ink I. You may comprise so that it may heat.

DESCRIPTION OF SYMBOLS 6 ... Ink cartridge (liquid storage part), 50 ... Deaeration tank, 50a ... 1st connection port, 50b ... 2nd connection port, 50c ... Canopy part, 51 ... Partition, 52 ... Opening, 53 ... Negative pressure air layer , 54 ... exhaust pipe, 55 ... check valve, 56 ... sensor, 100 ... printer (liquid ejecting apparatus), 105 ... maintenance mechanism, 112 ... capping mechanism, 113 ... suction pump, 110 ... head (ejection head), I ... Ink (liquid), TB ... Supply tube (supply path)

Claims (3)

A liquid reservoir for storing liquid;
An ejection head that ejects the liquid;
A supply path for supplying the liquid from the liquid reservoir to the ejection head;
A degassing tank provided in the middle of the supply path and disposed at a position higher than the liquid reservoir and the ejection head;
An exhaust pipe provided on the canopy of the deaeration tank;
A check valve provided in the exhaust pipe;
A liquid ejecting apparatus comprising:   The deaeration tank has a partition wall that separates between a connection port with the supply path on the storage unit side and a connection port with the supply path of the ejection head in a state where only the upper side which is the canopy side is opened. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is provided. The liquid ejecting apparatus according to claim 1, wherein the exhaust pipe is connected to a suction pump provided in a capping mechanism in a maintenance mechanism.

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