JP2008230162A - Liquid droplet delivering apparatus and sub-tank for liquid droplet delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet delivering apparatus capable of breaking a meniscus formed in a connecting part between a main tank and a sub-tank while the sub-tank for gas-liquid separation between the removable main tank and a delivering head. <P>SOLUTION: The sub-tank 23 installed in the liquid droplet delivering apparatus 1 includes a switching means for switching a condition from a condition that all of a liquid inlet 75a, a liquid outlet 77a and a first opening 78a communicate with each other through an inner space to a condition that only the liquid inlet 75a and the liquid outlet 77a communicate with each other through the inner space when the liquid level becomes to a specified position L or lower in the inner space. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge device including a discharge head that discharges liquid to a recording medium, and a sub tank that supplies the liquid supplied from the main tank to the discharge head when connected to a main tank that stores the liquid. And a sub-tank for the droplet discharge device.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus that forms an image on a recording medium such as a recording sheet by supplying ink from an exchangeable main tank (also referred to as an ink cartridge) to an ejection head and ejecting the ink from the ejection head There is. In such an ink jet recording apparatus, if the ink in the main tank is used up and then replaced with a new main tank, air may enter the ink supply path to the discharge head. There has been proposed a structure in which a sub-tank is interposed therebetween so that air does not enter the ink supply path to the ejection head (see, for example, Patent Documents 1 and 2).

In the configurations disclosed in Patent Documents 1 and 2, a main tank is connected from above to a sub-tank opened to the atmosphere, and this sub-tank is connected to the ejection head via a flexible tube. Therefore, even if the ink in the main tank is used up, since the ink remains in the sub tank, it is possible to prevent air from entering the tube leading to the ejection head. In addition, when the main tank is replaced, air may enter the connection between the main tank and the sub tank. When this air moves into the sub tank, the sub tank is released to the atmosphere, so it is separated from the ink by buoyancy. It will be discharged to the outside, and entry into the tube can be prevented.
JP 2002-307711 A JP 2005-66906 A

  By the way, in the case of the configuration disclosed in Patent Documents 1 and 2, when a new main tank is connected to the sub tank, a meniscus is formed by the air mixed in the flow path connecting the main tank and the sub tank. There is. When this meniscus is formed, it becomes difficult to supply ink from the main tank to the sub tank through the flow path, the ink in the sub tank is exhausted before the ink in the main tank is used up, and air is supplied from the sub tank to the tube. There is a possibility of intrusion.

  More specifically, the ejection head is provided with an actuator composed of a piezoelectric element or the like. The ejection head ejects ink from the nozzle hole by driving the actuator, and sucks ink from the main tank and the sub tank through the tube. To replenish. However, when a meniscus is formed in the flow path that connects the main tank and the sub tank, in order to break the meniscus and suck the ink in the main tank into the sub tank, it is necessary to make the inside of the sub tank have a negative pressure. As described above, since the sub tank is open to the atmosphere, it is difficult to break the meniscus. On the other hand, since the sub tank is opened to the atmosphere, the ink in the sub tank is supplied to the ejection head through the tube by driving the actuator. As a result, ink in the main tank is not supplied to the ejection head, but only ink in the sub tank is supplied, and air may enter the tube after the ink in the sub tank is used up.

  In addition, such a situation is not limited to an ink jet recording apparatus that forms an image by ejecting ink onto recording paper, and a sub-tank for gas-liquid separation is provided between a removable main tank and an ejection head that ejects droplets. This is common in all of the liquid droplet ejection devices provided.

  Accordingly, the present invention provides a liquid droplet ejection apparatus that can destroy a meniscus formed at a connection portion between a main tank and a sub tank while including a sub-tank for gas-liquid separation between a removable main tank and a ejection head. And a sub-tank for the droplet discharge device.

  The present invention has been made in view of the above-described circumstances, and a droplet discharge device according to the present invention includes a connection portion between a discharge head that discharges liquid to a recording medium and a main tank that stores the liquid. A sub-tank that supplies the liquid supplied from the main tank to the discharge head, and the sub-tank is a liquid flow into which the liquid flows from the main tank when the main tank is connected to the connection portion. An inlet, a liquid outlet through which liquid to be supplied to the discharge head flows out, and an atmosphere opening opening that communicates with the outside to open the interior space to the atmosphere; and the sub tank has a predetermined liquid level in the interior space. When the liquid inlet, the liquid outlet, and the atmosphere opening are all in communication with each other through the internal space, the liquid inlet and the liquid outlet Only has a switching means for switching to a state communicating with each other through the internal space.

  That is, when the liquid level falls below a predetermined position in the internal space of the sub tank by the switching means, all of the liquid inlet, the liquid outlet, and the atmosphere opening are in communication with each other through the internal space. The inlet and the liquid outlet are in communication with each other through the internal space, and the liquid inlet and the atmosphere opening, and the liquid outlet and the atmosphere opening are switched to a state where they are blocked without being in communication with each other. It has become.

  With such a configuration, the sub tank is opened to the atmosphere when the liquid level is higher than the predetermined position, and can be appropriately gas-liquid separated. Since the liquid does not communicate with the liquid inlet and the liquid outlet through the internal space, even if a meniscus is formed at the connecting portion between the main tank and the sub tank, the meniscus can be sucked into the sub tank and destroyed. As a result, the liquid in the main tank can be used up to the end.

  The switching means partitions the internal space into an upper chamber having the atmosphere opening and a lower chamber having the liquid inlet and the liquid outlet, and communicates between the upper chamber and the lower chamber. A partition formed with a valve seat having a communication hole, and a float that is accommodated in the upper chamber and has an outer shape capable of closing the communication hole and having a smaller specific gravity than the liquid. The upper chamber and the lower chamber may be configured to be liquid-tightly blocked from each other when the hole is closed. With such a configuration, the switching unit can be realized with a simple configuration without adopting a complicated and expensive configuration such as an electric drive mechanism.

  The lower chamber of the sub tank may be provided with a capture space capable of capturing air entering from the liquid inlet. With such a configuration, the air contained in the ink can be reliably captured in the sub tank, and the air mixed in the connecting portion between the main tank and the sub tank can also be reliably captured.

  The sub tank may further include a valve that opens and closes the atmosphere opening port, and the valve may be configured to close the atmosphere opening port when the main tank is not connected to the connection portion. . By adopting such a configuration, even if the liquid inlet of the sub tank is opened without being connected to the main tank, the inside of the sub tank excludes the liquid inlet because the atmosphere opening is closed. It becomes a sealed state. Accordingly, it is possible to prevent the liquid from leaking outside through the liquid inlet due to the negative pressure in the sub tank.

  A subtank according to the present invention is a subtank for a droplet discharge device that has a connection portion with a main tank that stores liquid and supplies the liquid supplied from the main tank to the discharge head. A liquid inlet through which liquid flows from the main tank when connected to the main tank, a liquid outlet through which liquid supplied to the discharge head flows out, and an open air that communicates with the outside to open the internal space to the atmosphere. The liquid inlet, the liquid outlet, and the atmosphere opening are all in communication with each other through the internal space when the liquid level in the internal space is below a predetermined position. And a switching means for switching to a state in which only the liquid inlet and the liquid outlet communicate with each other through the internal space.

  By adopting such a configuration, as described above, when the liquid level is higher than a predetermined position, the sub tank is opened to the atmosphere and can be appropriately gas-liquid separated, and the liquid level is below the predetermined position. Then, the meniscus at the connection between the main tank and the sub tank can be sucked into the sub tank and destroyed, and the liquid in the main tank can be used up to the end.

  According to the droplet discharge device according to the present invention, the meniscus formed at the connection portion between the main tank and the sub tank is destroyed while the gas-liquid separation sub tank is provided between the removable main tank and the discharge head. be able to. Further, according to the subtank for the droplet discharge device according to the present invention, the air in the ink can be appropriately gas-liquid separated and the meniscus formed at the connecting portion between the main tank and the subtank can be destroyed. it can.

  Hereinafter, a configuration of a droplet discharge device according to an embodiment of the present invention and a configuration of a sub tank for the droplet discharge device will be specifically described with reference to the drawings.

  FIG. 1 is a perspective view showing an external configuration of a droplet discharge device 1 according to an embodiment of the present invention. In this embodiment, the droplet discharge device 1 has a printer function, a scanner function, a copy function, a facsimile function, and the like. 1 shows a so-called multi-function machine equipped with. As shown in FIG. 1, the droplet discharge device 1 includes a printer unit 2 that records an image by an inkjet method at a lower part of a substantially rectangular parallelepiped casing 1 a and a scanner unit 3 at an upper part of the casing 1 a. It is configured.

  The printer unit 2 of the droplet discharge device 1 has an opening 4 on the front surface (front side) of the housing 1a. Inside the opening 4, a lower paper feed tray 5 and an upper paper discharge tray 6 are provided. Are provided in two stages. The paper feed tray 5 can store a plurality of recording sheets as a recording medium. For example, a plurality of recording sheets of various sizes of A4 size or less can be stored.

  A door 7 is provided at the lower right portion of the front of the printer unit 2 so as to be openable and closable, and a main tank mounting portion 8 (see FIG. 2) is provided inside the door 7. Therefore, when the door 7 is opened, the main tank mounting portion 8 is exposed to the front side, and the main tank (also referred to as an ink cartridge) 9 (see FIG. 2) is detachable from the horizontal direction. The main tank mounting unit 8 is provided with a storage chamber corresponding to the ink color to be used. In the printer unit 2, five color inks, that is, cyan (C) and magenta (M) which are dye inks are used. , Yellow (Y), photo black (PBk), and black (Bk) as a pigment ink are used. Therefore, the main tank mounting portion 8 is divided into five storage chambers, each of which includes cyan (C), magenta (M), yellow (Y), photo black (PBk), and black (Bk). A main tank 9 for storing each color ink is accommodated.

  The scanner unit 3 provided in the upper part of the droplet discharge device 1 is configured as a so-called flat bed scanner. That is, as shown in FIG. 1, a document cover 10 is provided on the upper surface of the droplet discharge device 1 so as to be opened and closed as a top plate of the droplet discharge device 1. A platen glass on which the document is placed, an image sensor that reads an image of the document, and the like are disposed below the document cover 10.

  An operation panel 11 for operating the printer unit 2 and the scanner unit 3 is provided on the front upper portion of the droplet discharge device 1. The operation panel 11 includes various operation buttons and a liquid crystal display, and the droplet discharge device 1 is operable based on an instruction output from the operation panel 11 as a result of operation of the operation panel 11 by the user. ing. Further, when the droplet discharge device 1 is connected to an external computer, the droplet discharge device 1 can be operated based on an instruction transmitted from the computer via a printer driver or a scanner driver. Yes.

  A slot portion 12 is provided in the upper left portion of the front surface of the droplet discharge device 1. Various small memory cards, which are storage media, can be loaded into the slot unit 12, and data stored in the small memory card loaded into the slot unit 12 can be read out by performing a predetermined operation on the operation panel 11. It has become. The read data can be displayed on the liquid crystal display of the operation panel 11, and an image arbitrarily selected based on this display can be recorded on the recording paper by the printer unit 2.

  FIG. 2 is a schematic cross-sectional view showing the configuration of the printer unit 2. As shown in FIG. 2, a paper feed tray 5 is provided near the bottom of the droplet discharge device 1, and a flat plate-like platen that is long in the left-right direction is provided above the paper feed tray 5. 14 is provided. Further above the platen 14 is provided an image recording unit 17 in which an ejection head 15 and the like for ejecting ink from the nozzle holes 15 a are mounted on the carriage 16. A paper transport path 18 extends from the rear of the paper feed tray 5. The sheet conveying path 18 is composed of a curved path 18a that is curved from the rear to the top of the paper feed tray 5 and further forward, and a straight path 18b that extends further forward from the end point of the curved path 18a. In the portion other than the place where the unit 17 is disposed, the outer guide surface and the inner guide surface are opposed to each other at a predetermined interval.

  A paper feed roller 19 for supplying the recording paper in the paper feed tray 5 to the paper transport path 18 is provided immediately above the paper feed tray 5. Also, in the vicinity of the downstream portion of the curved path 18a in the paper transport path 18, a pair of transport rollers 20 including a transport roller 20a and a pinch roller 20b are provided so that the paper transport path 18 is sandwiched from above and below by both rollers 20a and 20b. It has been. Further, in the vicinity of the downstream portion of the straight path 18b in the paper transport path 18, a pair of paper discharge rollers 21 including a paper discharge roller 21a and a pinch roller 21b sandwich the paper transport path 18 from above and below by both rollers 21a and 21b. Provided. The ejection head 15 and the platen 14 described above are provided between the conveying roller pair 20 and the paper discharge roller pair 21 so as to sandwich the straight path 18b from above and below.

  The discharge head 15 is supported by a guide rod (not shown) extending in the left-right direction (longitudinal direction of the platen 18) so as to be slidable in the left-right direction. It is connected to a head drive mechanism (not shown). Accordingly, when the head driving mechanism is driven, scanning within a predetermined range in the left-right direction along the guide rod is possible.

  According to such a printer unit 2, the recording paper in the paper feed tray 5 is supplied to the paper transport path 18 by the paper feed roller 19, and then on the paper transport path 18 from the curved path 18 a by the transport roller pair 20. It is conveyed to the straight path 18b. The recording paper that has reached the straight path 18b is recorded with the ink ejected from the ejection heads 15 disposed so as to face the recording paper. When the recording is completed, the recording paper is ejected from the straight path 18b by the ejection roller pair 21 and ejected to the ejection tray. 6 (see FIG. 1).

  Further, ink is supplied to the ejection head 15 provided in the printer unit 2 from a main tank 9 detachably attached to the main body of the droplet ejection apparatus 1. More specifically, as shown in FIG. 2, the droplet discharge device 1 includes a sub-tank 23 for gas-liquid separation. When the main tank 9 is attached to the tank mounting portion 8, the droplet discharge device 1 communicates with the main tank 9. Ink is supplied from the main tank 9. The sub tank 23 is connected to a buffer tank 25 connected to the upper part of the ejection head 15 via a flexible ink supply tube 24. Accordingly, by driving an actuator (not shown) composed of a piezoelectric element or the like included in the ejection head 15, ink in the ejection head 15 is ejected from the nozzle hole 15a, and ink in the sub tank 23 is ejected from the ink supply tube 24 and the buffer. The liquid is supplied to the discharge head 15 through the tank 25.

  As described above, in the droplet discharge device 1 according to the present embodiment, the main tank 9 and the sub tank 23 are directly connected, and the discharge head 15 and the sub tank 23 are connected to each other by the flexible ink supply tube 24. This is a so-called tube supply system in which an ink supply flow path from the main tank 9 to the ejection head 15 is always established. However, the application of the droplet discharge device and the subtank according to the present invention is not limited to such a tube-type configuration, and other configurations, for example, only when ink is replenished, the main tank 9 to the discharge head 15 are used. Needless to say, the present invention is also applicable to a station type (also referred to as on-demand type) configuration in which the ink supply flow paths are connected.

(Example 1)
Next, the structure which concerns on Example 1 about the main tank 9 and the subtank 23 is demonstrated.

[Configuration of main tank]
FIG. 3 is a vertical sectional view illustrating configurations of the main tank 9 and the sub tank 23 according to the first embodiment. As shown in FIG. 3, the main tank 9 is disposed on the side of the sub tank 23, and the main tank 9 has an ink storage chamber 43 that stores the ink 100. In the main tank 9, an opening 44 and a cylindrical valve storage chamber 45 continuous to the opening 44 are provided at the lower part of the wall surface (right side in FIG. 3) facing the sub tank 23. The valve storage chamber 45 extends from the opening 44 toward the inside of the main tank 9, and the ink supply valve 46 is stored in the valve storage chamber 45 there. A valve hole 47 is formed in the inner wall surface of the valve housing chamber 45, and a hollow conical cover portion 48 projects from the periphery of the valve hole 47 toward the inside of the main tank 9.

  An inflow hole 48 a is formed in the lower portion of the cover portion 48, and the valve storage chamber 45 communicates with the ink storage chamber 43 through the valve hole 47 and the inflow hole 48 a. A check valve 49 is provided in the valve hole 47, and the check valve 49 opens the valve hole 47 when the ink storage chamber 43 becomes a positive pressure with respect to the valve storage chamber 45, and the valve storage chamber When the ink storage chamber 43 has a negative pressure with respect to 45, the valve hole 47 is closed. An annular seal member 50 is provided in the opening 44, and an ink outflow hole 50a that is elastically reduced in diameter when no load is applied is formed at the center of the seal member 50.

  In the main tank 9, an opening 60 and a cylindrical valve housing chamber 61 continuous with the opening 60 are provided on the upper surface of the wall surface (the right side in FIG. 3) facing the sub tank 23. An annular seal member 62 is provided in the opening 60, and an air opening hole 62 a is formed at the center of the seal member 62. The valve storage chamber 61 extends from the opening 60 toward the inside of the main tank 9, and an air release valve 63 is stored in the valve storage chamber 61. The air release valve 63 has a rod portion 63a that passes through the air release hole 62a and protrudes outward toward the sub tank 23, and a flange portion 63b that protrudes radially outward from the inner end of the rod portion 63a. ing. The air release valve 63 is urged so that the flange portion 63b contacts the seal member 62 so as to seal the air release hole 62a. The rod portion 63a is provided with a groove portion 63c along the extending direction thereof. When the flange portion 63b is separated from the seal member 62, the valve housing chamber 61 is opened to the atmosphere via the groove portion 63c. A communication hole 64 is formed in the inner wall surface of the valve storage chamber 61, and the valve storage chamber 61 communicates with an air layer formed in the upper layer of the ink storage chamber 43 through the communication hole 64.

  In the main tank 9, a recess 42 is formed on the inner wall surface on the sub tank 23 side, and a space surrounded by the recess 42 is continuous with the ink storage chamber 43. On both side walls (the back side and the near side in FIG. 3) of the recess 42 are provided light transmitting portions 51 made of a translucent material for detecting the remaining amount of ink stored in the ink storage chamber 43. ing. Further, the main tank 9 has a support portion 52 for supporting the sensor arm 53 in a swingable manner. The sensor arm 53 includes a connecting portion 54 having a connecting shaft 54 a that is pivotally supported by the support portion 52, a float portion 55 that extends to one side of the connecting portion 54 (left side in FIG. 3), and the other side of the connecting portion 54 ( And an arm portion 56 extending on the right side of FIG.

  The float portion 55 is formed in a hollow shape so that the average specific gravity is lighter than the specific gravity of the ink. The arm portion 56 includes a first arm 56a, a second arm 56b, and a shielding portion 56c. The first arm 56 a extends upward from the connecting portion 54 so as to be substantially perpendicular to the float portion 55, and the second arm portion 56 b extends from the tip of the first arm 56 a in a direction away from the float portion 55. A shielding portion 56c is provided at the tip of the second arm portion 56b so as to be positioned in the recess 42.

  The arm portion 56 is set so that the weight is smaller than that of the float portion 55 and the buoyancy acting from the float portion 55 is small when immersed in ink. Accordingly, in a state where ink is not contained in the ink storage chamber 43, the sensor arm 53 rotates in the direction in which the float portion 55 descends about the connecting shaft 54a. At this time, the shielding portion 56c of the sensor arm 53 is recessed. It moves so as to retreat diagonally upward from within 42. On the other hand, when the ink storage chamber 43 is sufficiently filled with ink, the float portion 55 is immersed in the ink, the balance of the weight of the float portion 55 and the arm portion 56 is reversed by buoyancy, and the sensor arm 53 is connected to the connecting shaft 54a. The float part 55 rotates in the direction of ascending about the center. At that time, the shielding portion 56 c of the sensor arm 53 moves obliquely downward so as to enter the recess 42.

  The main tank mounting portion 8 (see FIG. 2) is provided with a remaining amount detection sensor 30. As shown in FIG. 3, the remaining amount detection sensor 30 is arranged such that when the main tank 9 is mounted on the main tank mounting portion 8, the concave portion 42 of the main tank 9 comes to a position corresponding thereto. . The remaining amount detection sensor 30 includes a light emitting unit and a light receiving unit (not shown) arranged to face each other with the main tank 9 interposed therebetween, and light emitted from the light emitting unit passes through the light transmitting unit 51 of the main tank 9 and is transmitted to the light receiving unit. Is received. Therefore, when the shielding portion 56 of the sensor arm 53 is positioned between the light transmitting portions 51 on both sides, the light receiving portion cannot receive light, and when the shielding portion 56 rotates and retracts from between the light transmitting portions 51, light reception is possible. Based on the presence or absence of such light reception, it is detected whether or not the position of the shielding portion 56, that is, whether or not the remaining amount of ink in the ink storage chamber 43 is equal to or greater than a predetermined amount (a small amount close to empty).

[Sub-tank configuration]
Next, the sub-tank 23 will be described. As shown in FIG. 3, the sub-tank 23 includes an ink storage container 70 positioned below to store ink, and an air release positioned above to release the inside of the ink storage container 70 to the atmosphere. It is comprised from the part 71, and has the height dimension substantially the same as the main tank 9. FIG. A partition plate 72 arranged horizontally is provided in the lower ink storage container 70, and is divided into a lower chamber 70a and an upper chamber 70b. A valve seat 72a is provided substantially at the center of the partition plate 72. The valve seat 72a has a communication hole formed by a round hole that penetrates the partition plate 72 in the vertical direction and communicates the lower chamber 70a and the upper chamber 70b. 72b is formed.

  In the lower chamber 70a of the ink storage container 70, a spherical float 73 having a diameter larger than the opening of the communication hole 72b is accommodated. Since the float 73 is designed to have a specific gravity smaller than that of the ink, when the lower chamber 70a is filled with ink, the float 73 is positioned upward due to buoyancy, while the liquid level of the ink descends as the ink level decreases, and the liquid level reaches a predetermined position. When it becomes L or less, the communication hole 72b of the valve seat 72a is closed (the state of the float 73 shown by a two-dot chain line in FIG. 3).

  In the lower chamber 70a, a flow path wall 74 is provided on the main tank 9 side, and an ink inflow path 74a is formed by the flow path wall 74 and the outer wall of the ink storage container 70. The ink inflow path 74a extends from an upper position of the partition plate 72 to a lower position reaching the vicinity of the inner bottom wall of the ink storage container 70, and communicates with the lower chamber 70a of the ink storage container 70 at the lower end thereof. ing. Further, the lower chamber 70 a is formed with a concave portion downwardly formed by a portion extending downward from the partition plate 72 in the flow path wall 74, the partition plate 72, and the outer wall surface of the ink storage container 70. An air capturing space 70c capable of capturing the air is formed. The air capturing space 70c is configured such that the volume thereof is larger than the volume of air that may be mixed into the connecting portion between the main tank 9 and the sub tank 23 when they are connected.

  In the sub tank 23, a cylindrical needle portion (connecting portion) 75 protrudes from the wall portion on the main tank 9 side toward the main tank 9 side, and the needle portion 75 has an ink inflow of the ink storage container 70. It has a liquid inlet 75a that opens toward the upper end of the channel 74a. The needle portion 75 is inserted into the ink outflow hole 50a of the seal member 50 of the main tank 9, so that the lower chamber 70a of the ink storage container 70 of the sub tank 23 and the ink storage chamber 43 of the main tank 9 are inflow of ink. It becomes the structure connected via the path | route 74a.

  Further, a hollow projecting portion 76 projects from the outer wall portion of the sub tank 23 in a direction away from the main tank 9. An internal space of the projecting portion 76 forms a part of the lower chamber 70a, and a tubular tube mounting portion 77 communicating with the space projects upward from the upper wall portion of the projecting portion 76. Has been. The tube attachment portion 77 has a liquid outlet 77a that opens toward the lower chamber 70a, and the liquid outlet 77a is provided at a position lower than the liquid inlet 75a. Then, one end of the ink supply tube 24 (see also FIG. 2) is connected to the tube mounting portion 77, so that the lower chamber 70 a of the ink storage container 70 of the sub tank 23 is connected to the image recording unit 17 via the ink supply tube 24. The buffer tank 25 (see FIG. 2) communicates.

  On the other hand, the air release portion 71 includes a labyrinth flow path 78 for gas-liquid separation that is configured so that the air flow direction is alternately switched from the top to the bottom and from the bottom to the top. One of the first openings 78a of the labyrinth channel 78 is located above the liquid inflow port 75a and is located at the uppermost end of the upper chamber 70b of the ink storage container 70 and opens toward the upper chamber 70b. It forms the atmosphere opening port of the ink storage container 70. Further, the other second opening 78 b is opened toward the outside of the sub tank 23. Therefore, the upper chamber 70 b of the ink storage container 70 communicates with the outside of the sub tank 23 via the labyrinth flow path 78.

[Sub tank function explanation]
The function of the sub tank 23 will be described in detail below as the function of the droplet discharge device 1 as described above. FIG. 4 is a drawing for explaining the function of the sub tank 23. FIG. 4A shows that the main tank 9 is mounted on the main tank mounting portion 8, and a meniscus is formed at the connection portion between the main tank 9 and the sub tank 23. The state is shown, and (b) shows how the meniscus is destroyed.

  As shown in FIG. 4A, when the main tank 9 is mounted on the main tank mounting portion 8 (see FIG. 2), the connecting portion between the main tank 9 and the sub tank 23 (in FIG. 4, the main tank in the needle portion 75). The air 101 is mixed in the vicinity of the end portion on the 9 side, and a meniscus is formed. When ink is ejected from the ejection head 15 (see FIG. 2) in this state, the ink in the sub tank 23 is supplied to the ejection head 15 through the ink supply tube 24, but the ink in the main tank 9 is blocked by the meniscus. It is not supplied to the sub tank 23. In FIG. 4A, a relatively large amount of ink is stored in the ink storage container 70 of the sub tank 23, and the liquid level is located at a predetermined position L or higher in the upper chamber 70b. Therefore, the float 73 is separated from the partition plate 72 upward and floats.

  Next, as shown in FIG. 4B, when the ink in the sub-tank 23 is reduced and the liquid level is lowered to below the predetermined position L, the float 73 is also lowered accordingly. The communication hole 72b formed in the valve seat 72a is closed to shut off the lower chamber 70a and the upper chamber 70b in a liquid-tight manner. Thus, the partition plate 72 having the valve seat 72a and the float 73 constitute switching means 90 that switches between the state in which the lower chamber 70a and the upper chamber 70b are in communication with each other and the state in which they are liquid-tightly shut off. ing.

  When the lower chamber 70a and the upper chamber 70b are blocked, the lower chamber 70a is also blocked from the atmosphere, that is, not released from the atmosphere through the atmosphere opening portion 71. Therefore, when ink is sucked to the discharge head 15 side through the ink supply tube 24 by ink discharge from the discharge head 15 in this state, the lower chamber 70a of the sub tank 23 becomes negative pressure, so that the ink in the main tank 9 is discharged. It is sucked into the sub tank 23. The air 101 forming the meniscus in the needle portion 75 moves together with the ink sucked from the main tank 9 side to the lower chamber 70a of the sub tank 23 through the ink inflow path 74a. As a result, the meniscus is destroyed and thereafter ink is supplied from the main tank 9 to the sub tank 23.

  Further, the air 101 that has moved together with the ink to the lower chamber 70a of the sub tank 23 is temporarily captured in an air capturing space 70c configured in the lower chamber 70a. As described above, the air capturing space 70c is configured to have a larger volume than the air 101, so that the air 101 entering the lower chamber 70a can be reliably captured when the meniscus is destroyed.

  Further, when ink is supplied from the main tank 9 to the sub tank 23, the ink level in the ink storage container 70 of the sub tank 23 rises as shown by the two-dot chain line in FIG. As a result, the float 73 also rises to open the communication hole 72b. Accordingly, the lower chamber 70a communicates with the upper chamber 70b and is released to the atmosphere through the labyrinth channel 78, and the air 101 moves to the upper chamber 70b through the communication hole 72b and enters the labyrinth channel 78 through the first opening 78a. The gas is discharged from the two openings 78b to the outside.

  As can be understood from the above description, the droplet discharge device 1 according to the present embodiment reliably destroys the meniscus even if a meniscus is formed when the main tank 9 and the sub tank 23 are connected to each other. Ink can be supplied from the tank 9 to the sub tank 23. After that, even if small-diameter air is mixed in the ink supplied from the main tank 9, it can be separated into gas and liquid by the function of the conventional sub tank 23 and discharged to the atmosphere. Intrusion of air into the supply tube 24 can be appropriately prevented.

(Example 2)
Next, the configuration of the droplet discharge device 1 according to the second embodiment, in particular, the configuration of the main tank 9 and the configuration of the sub tank 23 will be described. As described above, the main tank 9 according to the present embodiment is arranged on the side of the sub tank 23, and the needle portion 75 of the sub tank 23 is provided below the side wall portion of the sub tank 23. Therefore, if the main tank 9 is detached while ink remains in the ink storage container 70 of the sub tank 23, this residual ink may leak to the outside through the needle portion 75. However, as will be described later, the sub tank 23 according to the second embodiment is configured to prevent ink leakage when the main tank 9 is detached from the main tank mounting portion 8.

  FIG. 5 is a vertical cross-sectional view illustrating configurations of the main tank 9 and the sub tank 23 according to the second embodiment. As shown in FIG. 5, the labyrinth flow path 78 included in the sub tank 23 according to the second embodiment includes a second opening 80 that opens toward the main tank 9 side. A valve mechanism 81 is provided inside the second opening 80. The valve mechanism 81 includes a valve body 81a and a biasing means 81b including a coil spring. The valve body 81a is urged in a direction to close the second opening 80 by the urging means 81b.

  The main tank 9 according to the second embodiment includes an air release pin 82 protruding from the wall portion on the sub tank 23 side toward the sub tank 23 side. The air release pin 82 is disposed so as to be inserted into the second opening 80 of the sub tank 23 when the main tank 9 is attached to the main tank mounting portion 8. Accordingly, the inserted air release pin 82 moves the valve body 81a against the urging force of the urging means 81b, and opens the ink storage container 70 of the sub tank 23 to the atmosphere.

  Since the configurations of the main tank 9 and the sub tank 23 according to the second embodiment other than those described above are the same as the configurations according to the first embodiment shown in FIG. 3, detailed description thereof is omitted here.

  Next, the function of the sub tank 23 according to the second embodiment will be described. FIG. 6 is a diagram for explaining a function of preventing ink leakage from the sub tank 23. FIG. 6A shows a state in which the main tank 9 is located slightly away from the sub tank 23. ) Shows a state in which the two are completely separated.

  First, the case where the main tank 9 is detached from the state where the main tank 9 is mounted on the main tank mounting portion 8 (see FIG. 2) and connected to the sub tank 23 as shown in FIG. 5 will be described. As shown in FIG. 6 (a), when the main tank 9 is slightly separated from the sub tank 23 (more specifically, to the extent that the two are still in communication with each other via the needle portion 75), the second opening The air release pin 82 inserted through the valve 80 moves backward, and the valve body 81 a closes the second opening 80. Therefore, immediately before the main tank 9 is completely removed, the first opening 78a that opens toward the ink storage container 70 is closed to the atmosphere, and the ink storage container 70 is in a sealed state.

  In the state shown in FIG. 6A, at least the tip of the needle portion 75 of the sub tank 23 is inserted into the ink outflow hole 50a of the main tank 9, and the needle portion 75 is located between the needle portion 75 and the ink outflow hole 50a. There is no gap through which ink leaks. However, the main tank 9 and the sub tank 23 may communicate with each other via the needle part 75 or may not communicate with each other.

  Next, as shown in FIG. 6B, when the main tank 9 is completely separated from the sub tank 23, the needle portion 75 of the sub tank 23 is separated from the ink outflow hole 50a of the main tank 9, and the tip of the needle portion 75 is It will be open to the atmosphere. However, the opening at the tip of the needle portion 75 has a small diameter, and a meniscus is formed when the main tank 9 is separated from the ink outflow hole 50a. In addition, since the first opening 78a is closed in the ink storage container 70 of the sub tank 23, a negative pressure is generated due to the weight of the ink. Such meniscus and negative pressure prevent the ink in the sub tank 23 from leaking outside through the needle portion 75.

  As described above, in the main tank 9 and the sub tank 23 according to the second embodiment, when the main tank 9 is detached from the state in which the two communicate with each other through the liquid inlet 74a, the second opening 80 is first closed and the sub tank is closed. Then, the inside of the main tank 9 is hermetically sealed, and then the main tank 9 is completely detached from the sub tank 23 and the liquid inlet 74a is opened to the atmosphere. Therefore, even if the main tank 9 is detached while ink remains in the sub tank 23, the residual ink in the sub tank 23 does not leak outside through the liquid inlet 74a.

  On the other hand, when a new main tank 9 is mounted on the main tank mounting portion 8 and connected to the sub tank 23, the state shown in FIG. 6B is changed from the state shown in FIG. Then, the state shifts to the connection state shown in FIG. That is, when the main tank 9 is connected to the sub-tank 23, first, as shown in FIG. 6B, from the state where both are completely separated, as shown in FIG. Is inserted into the ink outlet hole 50a of the main tank 9 (however, the main tank 9 and the sub tank 23 may or may not communicate with each other via the liquid inlet 74a). In this state, the second opening 80 is not opened. After that, when the main tank 9 is completely mounted on the main tank mounting portion 8 (see FIG. 2), the needle portion 75 is further inserted deeply as shown in FIG. 5, and the second opening 80 is opened. The inside of the ink storage container 70 of the sub tank 23 is opened to the atmosphere, and the main tank 9 and the sub tank 23 are in communication with each other via the liquid inflow port 74a.

  Therefore, when the main tank 9 is completely attached to the main tank mounting portion 8 and the main tank 9 and the sub tank 23 communicate with each other, the sub tank 23 is opened to the atmosphere. Ink is smoothly supplied to the ink supply 23. Further, when the inside of the sub tank 23 is opened to the atmosphere, the tip of the needle portion 75 is inserted into the ink outflow hole 50a of the main tank 9, so that the ink in the sub tank 23 leaks outside through the liquid inflow port 74a. Nor.

  Note that the configuration according to the second embodiment also includes the switching unit 90 similar to that according to the first embodiment, and has the same operational effects as those of the configuration according to the first embodiment described above. it can.

(Example 3)
Next, the configuration of the droplet discharge device 1 according to the third embodiment, particularly the configuration of the sub tank 23 will be described. FIG. 7 is a vertical cross-sectional view illustrating the configuration of the sub tank 23 according to the third embodiment. As shown in FIG. 7, the sub-tank 23 according to the third embodiment is almost the same as the configuration according to the first embodiment (see FIG. 3), but an electromagnetic valve that opens and closes the second opening 78 b of the labyrinth channel 78. The difference is that 83 is provided.

  Further, the main tank mounting portion 8 is provided with a sensor 85 for detecting that the main tank 9 is attached thereto. More specifically, the sensor 85 is configured such that the main tank 9 is being detached from the main tank mounting portion 8 or is being attached to the main tank mounting portion 8 and the ink supply valve 46 of the main tank 9 is in a closed state ( It is possible to detect whether the tip of the needle portion 75 of the sub tank 23 is inserted into the ink outflow hole 50a of the main tank 9 (hereinafter referred to as “valve drive state”) when the main tank 9 is sealed). It has become.

  In the sub-tank 23 according to the third embodiment having such a configuration, when the main tank 9 is detached, when the valve driving state is detected by the sensor 85, the detection signal is a control unit included in the droplet discharge device 1. (Not shown). This control unit drives the electromagnetic valve 83 based on the input signal, and switches the second opening 78b of the sub tank 23 from the open state to the closed state. The closing operation of the second opening 78b by the electromagnetic valve 83 is completed during the valve driving state as described above, and then the main tank 9 is completely detached from the sub tank 23.

  When the main tank 9 is connected to the sub-tank 23, when both approach and the valve driving state is detected by the sensor 85, the detection signal is input to the control unit, and the control unit drives based on this. Output a signal. The electromagnetic valve 83 switches the second opening 78b from the closed state to the open state based on this drive signal. Then, the opening operation of the second opening 78b by the electromagnetic valve 83 is completed during the valve driving state as described above, and then the main tank 9 is completely connected to the sub tank 23, both of which are needles. The communication is made through the section 75.

  Accordingly, also in the sub tank 23 according to the third embodiment, the leakage of residual ink from the sub tank 23 can be prevented when the main tank 9 is detached as described in the second embodiment. The operational effect that smooth ink supply is possible can be achieved, and the same operational effect as described in the first embodiment can be achieved.

  In the second and third embodiments, the configuration for opening and closing the second openings 78b and 80 of the sub tank 23 has been described. Needless to say, the first opening 78a may be opened and closed. A mechanism for opening and closing the flow path may be provided in the middle of the flow path from the ink storage container 70 to the second openings 78b and 80. Even in such a case, the same effects as described above can be obtained.

  In the above description, the tube type configuration in which the discharge head 20 and the sub tank 23 communicate with each other even during image formation has been described. However, for example, a so-called station supply method (also referred to as an on-demand method) is used. Is also applicable. In addition, the main tank 9 and the sub tank 23 are not limited to the configuration in which the main tank 9 and the sub tank 23 are directly connected to each other, and the configuration in which the both are indirectly connected through another tubular member having flexibility, for example. Even so, the present invention can be applied. Furthermore, the present invention is not limited to those that eject ink, and the present invention is applicable to any droplet ejection device that includes a sub tank that stores liquid to be supplied to the ejection head and that can communicate with the sub tank. can do.

  The present invention provides a droplet discharge device capable of destroying a meniscus formed at a connection portion between a main tank and a sub tank, while including a sub-tank for gas-liquid separation between a removable main tank and a discharge head, And it is applicable to the sub tank used for this.

It is a perspective view which shows the external appearance structure of the droplet discharge apparatus which concerns on embodiment of this invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a printer unit. FIG. 3 is a vertical cross-sectional view illustrating configurations of a main tank and a sub tank according to the first embodiment. It is drawing for demonstrating the function of a sub tank, (a) shows the state by which the main tank was mounted in the main tank mounting part, and the meniscus was formed in the connection part of a main tank and a sub tank, (b) is this It shows how the meniscus is destroyed. FIG. 6 is a vertical cross-sectional view illustrating configurations of a main tank and a sub tank according to a second embodiment. It is drawing for demonstrating the function which prevents the ink leakage from a subtank, (a) shows the state where the main tank is located in the some distance away from a subtank, (b) shows both completely It shows a separated state. It is a vertical sectional view showing the configuration of the sub tank according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Droplet discharge device 8 Main tank mounting part 9 Main tank 23 Sub tank 43 Ink storage chamber 70 Storage container 70a Lower chamber 70b Upper chamber 70c Capture space 71 Atmospheric release part 72 Partition plate 72a Valve seat 72b Communication hole 73 Float 74 Channel wall 74a Ink inflow path 75 Needle part (connection part)
75a Liquid inlet 77a Liquid outlet 78 Labyrinth flow path 78a First opening (atmospheric opening)
78b Second opening 80 Second opening 81 Valve mechanism 82 Atmospheric release pin 83 Solenoid valve 85 Sensor 90 Switching means 101 Air

Claims (5)

An ejection head for ejecting liquid onto a recording medium;
A sub-tank having a connecting portion with a main tank for storing liquid and supplying the liquid supplied from the main tank to the discharge head;
The sub tank
When the main tank is connected to the connecting portion, a liquid inlet through which liquid flows from the main tank, a liquid outlet from which liquid supplied to the discharge head flows out, and an external space communicating with the atmosphere With an open air opening,
Further, the sub-tank is in a state in which all of the liquid inlet, the liquid outlet, and the atmosphere opening are in communication with each other through the inner space when the liquid level in the inner space becomes a predetermined position or less. A liquid droplet ejection apparatus, comprising: a switching unit that switches to a state in which only the liquid inlet and the liquid outlet communicate with each other through the internal space. The switching means is
The valve seat having a communication hole for partitioning the internal space into an upper chamber having the atmosphere opening and a lower chamber having the liquid inlet and the liquid outlet and communicating between the upper chamber and the lower chamber A partition formed with,
The float is housed in the upper chamber and has an outer shape capable of closing the communication hole and has a smaller specific gravity than the liquid.
2. The droplet discharge device according to claim 1, wherein when the float closes the communication hole, the upper chamber and the lower chamber are blocked from each other in a liquid-tight manner.   The droplet discharge device according to claim 2, wherein the lower chamber of the sub tank is provided with a capture space capable of capturing air entering from the liquid inflow port.   The sub-tank further includes a valve for opening and closing the atmosphere opening port, and the valve is configured to close the atmosphere opening port when the main tank is not connected to the connection portion. The droplet discharge device according to claim 1. A sub-tank for a droplet discharge device that has a connection with a main tank for storing liquid and supplies the liquid supplied from the main tank to the discharge head,
When the main tank is connected to the connection portion, a liquid inlet through which liquid flows from the main tank, a liquid outlet from which the liquid supplied to the discharge head flows out, and the interior space are opened to the atmosphere by communicating with the outside. And open to the atmosphere,
Furthermore, when the liquid level in the internal space becomes a predetermined position or less, the liquid inflow port, the liquid outflow port, and the atmosphere opening port are all in communication with each other through the internal space. And a sub-tank for a droplet discharge device, comprising: switching means for switching to a state in which only the liquid outlets communicate with each other through the internal space.

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