JP2011037091A - Liquid tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid tank which efficiently separates air bubbles included in a liquid. <P>SOLUTION: A storage chamber 50 of a sub tank 80 has: an inflow chamber 51 having inlets 83a and 84a to which an ink from an ink jet head flows in; an internal channel 52 which communicates with the inflow chamber 51 by a slit 61; and an outflow chamber 53 which communicates with the internal chamber 52 by a slit 62 having an outlet 82a formed to flow out the ink supplied to the ink jet head. An ink inflow direction of the inlets 83a, 84a is made a direction orthogonal to straight lines X1, X2 which connect centers of the inlets 83a, 84a with the center of the slit 61 seen from the gravity direction, and toward an inner wall surface of the inflow chamber 51 on the opposite side to the slit 61 with respect to straight lines Y1, Y2 that pass the centers of the inlets 83a, 84a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid tank that stores liquid flowing in from the outside and discharges the stored liquid to the outside.

The ink tank provided in the ink jet printer stores the ink that flows in from the outside, and discharges the stored ink to the outside in order to supply the ink to the ink jet head. Ink that has flowed in from the outside may contain air bubbles, and the air bubbles contained in the ink may cause obstacles such as blocking the flow path of the ink jet head and reduce the function of the ink jet head. It is necessary to separate the bubbles from the ink that has flowed in so that the ink containing the bubbles does not flow outside. In order to separate bubbles from the ink that flows in, an ink tank is known that has an internal channel that extends from the inlet into which the ink flows in along the ink inflow direction and then bends multiple times in the vertical direction ( Patent Document 1). According to this ink tank, the ink flowing in from the inflow port flows while repeatedly bending in the vertical direction in the internal flow path, whereby the bubbles are separated from the ink.
It is not limited to the ink jet printer that the liquid containing bubbles is supplied from the liquid tank, but the function of the supplied device is not limited to the ink jet printer. It is a well-known fact that can occur.

JP 2001-260388 A

  In the technique described above, since the ink containing bubbles is directly introduced into the narrow internal flow path, it is difficult to efficiently separate the bubbles when the flowing ink contains a large amount of bubbles.

  An object of the present invention is to provide a liquid tank capable of efficiently separating bubbles contained in a liquid.

  The liquid tank of the present invention includes a storage chamber for storing liquid, an inflow channel for allowing liquid to flow into the storage chamber from an inlet opening in the storage chamber, and an outlet from the storage chamber for opening the storage chamber. And an outflow channel through which liquid flows out. An inflow chamber having an inlet opening is formed in the storage chamber as a part of the storage chamber, and the inflow chamber and the remaining portion of the storage chamber communicate with each other through a first connection port. As seen from the direction, the inflow direction of the liquid from the inlet to the storage chamber is orthogonal to a straight line connecting the center of the inlet and the center of the first connection port, and passes through the center of the inlet. The direction toward the inner wall surface of the inflow chamber on the opposite side to the first connection port.

  From another point of view, the liquid tank of the present invention has a storage chamber for storing the liquid, an inflow channel for allowing the liquid to flow into the storage chamber from an inlet opening in the storage chamber, and an opening in the storage chamber. And an outflow passage through which liquid flows out from the storage chamber through the outflow port. An inflow chamber having an inlet opening is formed in the storage chamber as a part of the storage chamber, and the inflow chamber and the remaining portion of the storage chamber communicate with each other through a first connection port. When viewed from the direction, at the intersection of a straight line passing through the center of the inlet and extending in the liquid inflow direction from the inlet to the storage chamber and the inner wall surface of the inlet chamber, the intersection extends along the inner wall surface. In addition, the angle formed between the direction approaching the center of the first connection port and the inflow direction exceeds 90 degrees.

  According to the present invention, since the liquid flowing in from the inlet flows so as to be reversed along the inner wall surface of the inlet chamber and reaches the first connection port, the liquid flowing from the inlet to the first connection port The length of the path becomes long, and it is possible to secure a time for the bubbles contained in the liquid to separate from the liquid. Thereby, it is possible to efficiently separate bubbles contained in the liquid with a simple structure.

  In this invention, it is preferable that the said inflow channel is extended toward upper direction from the gravity direction lower direction in the said inflow chamber, and has the said inflow port in an upper edge part. According to this, since the bubbles contained in the liquid can be quickly moved to the water surface in the inflow channel, the bubbles contained in the liquid can be more efficiently separated.

  In the present invention, it is preferable that a guide wall for guiding the liquid flowing into the inflow chamber from the inflow port in the inflow direction is formed in the inflow chamber. According to this, since the liquid flowing into the inflow chamber surely flows in the inflow direction, the path length of the liquid from the inflow port to the first connection port is reliably increased, and the bubbles included in the liquid are separated from the liquid. Time can be secured.

  Furthermore, in the present invention, an internal flow path communicating with the inflow chamber via the first connection port is further formed in the remaining portion of the storage chamber, and the internal flow path is formed in the internal flow path. It is preferable that a first wall body is formed that extends upward from the bottom surface of the storage chamber, which forms a wall portion of the path and bends the liquid flow path in the internal flow path. According to this, the path length of the liquid in the storage chamber can be further increased.

  At this time, it is more preferable that the recessed corner portion of the first wall body is formed of a curved surface. According to this, it can suppress that a bubble stays in the recessed corner | angular part of a 1st wall body.

  In the present invention, a second wall extending downward from the upper surface of the storage chamber is formed along the at least part of the first wall in the internal flow path. Also good. According to this, since it is suppressed that the liquid in an internal flow path gets over a 1st wall body, the path | route length of the liquid in the said internal flow path can be lengthened reliably.

  At this time, it is preferable that the concave corner portion of the second wall body is formed of a curved surface. According to this, it is possible to suppress the bubbles from remaining in the recessed corners of the second wall body.

  In the present invention, it is preferable that a supply port for supplying a liquid to the internal flow path is formed, and at least a part of the liquid flowing out from the outflow port flows in from the inflow port. According to this, the liquid supplied from the supply port is mixed with the liquid supplied from the inflow port and likely to contain a lot of bubbles, and the bubbles are prevented from being dispersed in the liquid supplied from the supply port. it can.

  Further, in the present invention, an outflow chamber in which the outflow port is formed is further formed as a part of the storage chamber in the storage chamber, and the outflow chamber and the internal flow path are connected to the second connection. It is preferable that a liquid level sensor that communicates via a mouth and detects the height of the liquid level in the outflow chamber is disposed in the outflow chamber. According to this, the bubbles separated from the liquid disappear on the water surface until reaching the outflow chamber, and the liquid from which the bubbles are removed is stored in the outflow chamber. Therefore, the liquid remaining in the storage chamber is detected from the detection result of the liquid level sensor. The amount can be detected accurately.

  According to the present invention, since the liquid flowing in from the inlet flows so as to be reversed along the inner wall surface of the inlet chamber and reaches the first connection port, the liquid flowing from the inlet to the first connection port The length of the path becomes long, and it is possible to secure a time for the bubbles contained in the liquid to separate from the liquid. Thereby, it is possible to efficiently separate bubbles contained in the liquid with a simple structure.

1 is a schematic plan view of an ink jet printer according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the inkjet head and ink supply unit shown in FIG. It is a cross-sectional view of the sub tank shown in FIG. It is sectional drawing of the IV-IV line shown in FIG. (A) It is sectional drawing of the VA-VA line shown in FIG. (B) It is an enlarged view of the circular area | region VB shown in FIG. It is sectional drawing of the VI-VI line shown in FIG. FIG. 2 is a diagram illustrating an ink flow when ink circulation is performed for the inkjet head illustrated in FIG. 1. It is a cross-sectional view of a sub tank according to a modification. It is a cross-sectional view of a sub tank according to a further modification.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the ink jet printer 101 includes a transport unit 20 that transports the paper P from the upper side to the lower side of FIG. 1, and inks of magenta, cyan, yellow, and black on the paper P transported by the transport unit 20. The apparatus includes four inkjet heads 1 that respectively eject droplets, four ink supply units 10 that supply ink to the inkjet head 1, and a control device 16. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction.

  The transport unit 20 includes two belt rollers 6 and 7 and an endless transport belt 8 wound between the rollers 6 and 7. The belt roller 7 is a driving roller, and rotates when a driving force is applied from a conveyance motor (not shown). The belt roller 6 is a driven roller and rotates as the conveyor belt 8 travels due to the rotation of the belt roller 7. The paper P placed on the outer peripheral surface of the transport belt 8 is transported downward in FIG.

  The four inkjet heads 1 each extend along the main scanning direction and are arranged in parallel to each other in the sub-scanning direction. That is, the ink jet printer 101 is a line type color ink jet printer in which a plurality of ejection openings for ejecting ink droplets are arranged in the main scanning direction. The lower surface of each inkjet head 1 is a discharge surface 2a in which a plurality of discharge ports are arranged (see FIG. 2).

  When the paper P transported by the transport belt 8 passes immediately below the four ink jet heads 1, ink droplets of each color are sequentially ejected from the respective ink jet heads 1 toward the upper surface of the paper P, and the paper P is ejected onto the paper P. A desired color image is formed.

  The ink supply unit 10 is connected to the vicinity of the left end of FIG. 1 on the lower surface of the inkjet head 1 and supplies ink to the connected inkjet head 1.

  Next, the inkjet head 1 will be described in detail with reference to FIG. As shown in FIG. 2, the inkjet head 1 includes a reservoir unit 71 and a head body 2.

  The reservoir unit 71 is a flow path forming member that supplies ink to the head body 2 and is fixed to the upper surface of the head body 2. The reservoir unit 71 has an ink inflow channel 72, an ink outflow channel 75, a first exhaust channel 73, and a second exhaust channel 74 formed therein.

  The ink inflow channel 72 has an inflow port 72 a that opens on the lower surface of the reservoir unit 71. Ink from the ink supply unit 10 flows into the ink inflow channel 72 from the inflow port 72a. The ink inflow channel 72 has a function as an ink reservoir for temporarily storing the inflowed ink. A hole 72 b penetrating to the upper and outer wall surfaces of the reservoir unit 71 is formed in the inner wall surface of the ink inflow channel 72. The hole 72b is sealed from the outside of the reservoir unit 71 with a resin film 76 having flexibility. The resin film 78 forms a part of the inner wall surface of the ink inflow channel 72. Since the resin film 76 is displaced in accordance with the change in the ink pressure in the ink inflow channel 72, the resin film 76 has a damper function for suppressing the change in the ink pressure. By using the resin film 76, the damper function can be realized with an inexpensive configuration. During normal printing, the resin film 76 is slightly convex toward the ink inflow channel 72. A plate-shaped restricting member 77 is fixed to the outer wall surface of the reservoir unit 71 so as to cover the resin film 76, and restricts the resin film 76 from protruding toward the outside of the reservoir unit 71. Thus, when the ink pressure in the ink inflow channel 72 becomes abnormally high, the resin film 76 is prevented from being excessively displaced and damaged. An air communication hole 77 a is formed in the restriction member 77, and the atmospheric pressure is always between the restriction member 77 and the resin film 76. Thereby, the resin film 76 becomes easy to displace.

  The ink outflow channel 75 communicates with the ink inflow channel 72 via the filter 75a and also communicates with the head body 2. During normal printing, ink from the ink supply unit 10 passes through the ink inflow channel 72 and the ink outflow channel 75 and is supplied to the head body 2.

  The first exhaust passage 73 communicates with the ink inflow passage 72 on the upstream side of the filter 75 a and is connected to the ink supply unit 10 via a first outlet 73 a formed on the lower surface of the reservoir unit 71. ing. A hole 73 b that penetrates to the lower outer wall surface of the reservoir unit 71 is formed in the lower inner wall surface of the first exhaust passage 73. The hole 73b is sealed from the outside of the reservoir unit 71 by a resin film 78 having flexibility. The resin film 78 forms a part of the inner wall surface of the first exhaust flow path 73. Since the resin film 78 is displaced as the ink pressure in the first exhaust passage 73 varies, the resin film 78 has a damper function that suppresses variation in the ink pressure. By using the resin film 78, the damper function can be realized with an inexpensive configuration. During normal printing, the resin film 78 is slightly convex toward the inside of the first exhaust flow path 73. A plate-shaped regulating member 79 is fixed to the lower outer wall surface of the reservoir unit 71 so as to cover the resin film 78, and regulates the resin film 78 from protruding toward the outside of the reservoir unit 71. . This prevents the resin film 78 from being excessively displaced and damaged when the ink pressure in the first exhaust flow path 73 becomes abnormally high. An air communication hole 79 a is formed in the regulating member 79, and the atmospheric pressure is always between the regulating member 79 and the resin film 78. Thereby, the resin film 78 becomes easy to displace. During the first ink circulation described later, the ink from the ink supply unit 10 passes through the ink inflow channel 72 and the first exhaust channel 73 and returns to the ink supply unit 10 from the outlet 73a (FIG. 7). (See (a)).

  The second exhaust flow path 74 communicates with the head body 2 and is connected to the ink supply unit 10 via a second outlet port 74 a formed on the lower surface of the reservoir unit 71. During the second ink circulation described later, the ink from the ink supply unit 10 passes through the ink inflow passage 72, the ink outflow passage 75, and the head main body 2, and then passes through the second exhaust passage 74. Then, it returns to the ink supply unit 10 (see FIG. 7B).

  The head main body 2 includes a common ink chamber that communicates with the ink outflow passage 75 and the second exhaust passage 74 of the reservoir unit 71, and a flow passage unit that includes a plurality of individual ink passages that communicate with the common ink chamber ( And an actuator unit (not shown). The individual ink flow path extends from the common ink chamber to the discharge port that opens to the discharge surface 2a via the pressure chamber. The actuator unit includes a plurality of actuators corresponding to each pressure chamber, and has a function of selectively applying ejection energy to ink in the pressure chamber.

  During normal printing, the ink supplied from the ink outflow passage 75 of the reservoir unit 71 flows from the common ink chamber into each individual ink passage and reaches the discharge port. In addition, during the second ink circulation described later, the ink supplied from the ink outflow passage 75 of the reservoir unit 71 passes from the common ink chamber to the second exhaust passage 74 of the reservoir unit 71 via a discharge port (not shown). It flows in (see FIG. 7B).

  The ink supply unit 10 will be described in detail. As shown in FIG. 2, the ink supply unit 10 includes a sub tank 80, an ink supply pipe 81 connected to the sub tank 80, an ink supply pipe 82, a first ink return pipe 83, a second ink return pipe 84, and an ink supply. A pump 86 provided on the pipe 82, a first valve 87 provided on the first ink return pipe 83, and a second valve 88 provided on the second ink return pipe 84 are provided.

  As shown in FIGS. 3 to 6, the sub tank 80 has a casing 80 a having an opening on the upper side and an upper lid 80 b covering the opening, and is supplied to the ink jet head 1 by combining these. A storage chamber 50 for storing ink is formed. An inflow chamber 51, an internal flow path 52, and an outflow chamber 53 are formed in the storage chamber 50 so as to communicate with each other. The inflow chamber 51 has a rectangular parallelepiped internal space.

  As shown in FIGS. 3 and 4, two convex portions 66 a and 66 b having a cylindrical shape are formed near the center of the bottom surface of the inflow chamber 51. In the side surface of the convex portion 66a, an inflow port 83a extending in the circumferential direction is opened centering on a point closest to the inner wall surface in the lower part in FIG. The bottom wall of the sub tank 80 extends obliquely upward toward the inner wall surface from the lower surface of the sub tank 80 so as to pass through the bottom wall of the sub tank 80 including the convex portion 66a. An inflow flow path 68a having the shape is formed. A first ink return pipe 83 is connected to the lower end of the inflow channel 68a. The ink that has flowed into the inflow channel 68a from the first ink return pipe 83 flows into the inflow chamber 51 from the inflow port 83a. The ink inflow direction of the inflow port 83a is a direction perpendicular to the inner wall surface of the inflow chamber 51 in the lower part of FIG.

  In the side surface of the convex portion 66b, an inflow port 84a that extends in the circumferential direction with the portion closest to the lower inner wall surface in FIG. The bottom wall of the subtank 80 extends obliquely upward from the lower surface of the subtank 80 through the bottom wall of the subtank 80 including the convex portion 66b and toward the inner wall surface, and has an inlet at its upper end. An inflow channel 68b having 84a is formed. A second ink return pipe 84 is connected to the lower end of the inflow channel 68b. The ink that has flowed into the inflow passage 68b from the second ink return pipe 84 flows into the inflow chamber 51 from the inflow port 84a. The ink inflow direction of the inflow port 84a is a direction perpendicular to the lower inner wall surface in FIG.

  Further, the bottom surface of the inflow chamber 51 extends in a U shape so as to circumscribe the outer peripheral surface of each of the convex portions 66a and 66b and to have an opening in the ink inflow direction of the inflow ports 83a and 84a in plan view. Existing guide walls 67a and 67b are formed. The upper ends of the guide walls 67b and 67b are higher than the upper ends of the convex portions 66a and 66b. Further, the vicinity of both ends of the guide walls 67a and 67b extends in the ink inflow direction from the vicinity of both ends of the inflow ports 83a and 84a. Thereby, the guide walls 67a and 67b guide the ink flowing into the inflow chamber 51 from the inflow ports 83a and 84a so as to flow in the ink inflow direction toward the inner wall surface of the inflow chamber 51 in the lower part in FIG.

  A slit (first connection port) 61 extending in the vertical direction with respect to the direction of gravity is formed at the left end in FIG. 3 of the inner wall surface of the inflow chamber 51 in the direction opposite to the ink inflow direction with respect to the inflow ports 83a and 84a. ing. The inflow chamber 51 and the internal flow path 52 adjacent to the inflow chamber 51 communicate with each other through the slit 61. In this embodiment, when viewed from the direction of gravity, the ink inflow direction of the inflow port 83a is a straight line Y1 orthogonal to the straight line X1 connecting the center of the inflow port 83a and the center of the slit 61 and passing through the center of the inflow port 83a. In contrast, the ink inflow direction of the inflow port 84a is orthogonal to a straight line X2 connecting the center of the inflow port 84a and the center of the slit 61. It can be said that the direction is toward the inner wall surface of the inflow chamber 51 on the opposite side of the slit 61 with respect to the straight line Y2 passing through the center of the inflow port 84a.

  As shown in FIGS. 3 and 5A, a wall 63 extending upward from the bottom surface of the housing 80 a is disposed in the internal flow path 52. The wall 63 defines a flow path shape in the internal flow path 52. The internal flow path 52 is adjacent to the inflow chamber 51 and the outflow chamber 53, communicates with the inflow chamber 51 through the slit 61, and includes a slit 62 formed at the corner farthest from the slit 61. And the outflow chamber 53 communicate with each other. The wall body 63 bends the flow of ink from the slit 61 to the slit 62. Furthermore, a wall body 64 that extends downward from the upper surface of the upper lid 80 b is disposed in the internal flow path 52 so as to follow a portion of the wall body 63 that separates the internal flow path 52 and the outflow chamber 53. . As a result, the ink in the internal flow path 52 is prevented from flowing over the wall 63 and into the outflow chamber 53 (see FIG. 6). As shown in FIG.5 (b), the recessed corner | angular part of the wall bodies 63 and 64 is formed in the curved surface. Thereby, it is suppressed that a bubble stays in the recessed corner | angular part of wall body 63,64.

  A supply port 81a is formed on the upper left in FIG. An ink supply pipe 81 is connected to the supply port 81a. The ink stored in the ink tank 90 is supplied from the ink supply pipe 81 to the internal flow path 52 through the supply port 81a. Ink flowing into the internal flow path 52 from the inflow chamber 51 through the slit 61 and ink flowing from the ink tank 90 into the internal flow path 52 through the supply port 81 a flow into the outflow chamber 53 through the slit 62. .

  As shown in FIGS. 3 and 6, an ink supply pipe 82 is connected to the bottom wall of the sub tank 80 at the lower end, and a discharge channel 69 having an outlet 82 a that opens to the bottom surface of the outflow chamber 53 at the upper end. Is formed. The ink that has flowed into the outflow chamber 53 from the slit 62 is stored in the outflow chamber 53, and the stored ink flows out from the outflow port 82 a through the discharge channel 69 to the ink supply pipe 82. On the upper surface of the outflow chamber 53, a reflective optical liquid level sensor 80c that detects the height of the liquid level of the ink stored in the outflow chamber 53 is disposed. The detection result of the liquid level sensor 80 c is output to the control device 16. The control device 16 determines the amount of ink stored in the storage chamber 50 from the detection result of the liquid level sensor 80c.

  As shown in FIG. 2, the ink supply pipe 82 communicates with the sub tank 80 at one end via the outflow port 82a, and communicates with the reservoir unit 71 at the other end via the inflow port 72a. The ink stored in the outflow chamber 53 of the sub tank 80 is supplied to the ink inflow channel 72 of the reservoir unit 71 through the ink supply pipe 82. The pump 86 functions as a supply unit that forcibly supplies the ink stored in the outflow chamber 53 to the reservoir unit 71 via the ink supply pipe 82, and the ink is supplied from the ink supply pipe 82 toward the outflow chamber 53. It also functions as a check valve that prevents flow.

  The first ink return pipe 83 communicates with the sub-tank 80 at one end via the inflow port 83a, and communicates with the reservoir unit 71 at the other end via the first outflow port 73a. The first valve 87 is an adjustment valve that adjusts the ink flow rate in the first ink return pipe 83.

  The second ink return pipe 84 communicates with the sub tank 80 at one end via the inflow port 84a, and communicates with the reservoir unit 71 at the other end via the second outflow port 74a. The second valve 88 is an adjustment valve that adjusts the ink flow rate in the second ink return pipe 84.

  The control device 16 controls the entire inkjet printer 101. At the time of printing, the control device 16 closes the first valve 87 and the second valve 88 and then controls the transport unit 20 so that the paper P is transported at a predetermined speed. Each ink-jet head 1 is controlled so that ink droplets are ejected from the respective ejection ports at the timing when an image is formed on the paper P when passing under the ink-jet head 1.

  Further, the control device 16 controls the operations of the pump 86, the first valve 87, and the second valve 88 of each ink supply unit 10 in a maintenance operation described later. The maintenance operation will be described with reference to FIG. The maintenance operation is an operation for performing maintenance of the inkjet head 1 and is started when the inkjet printer 101 is activated, when a standby time exceeds a certain time, and when an instruction is given from the user. During standby and normal printing, the pump 86 is stopped and the first valve 87 and the second valve 88 are closed (see FIG. 2). Then, when the maintenance operation is started, the first circulation operation and the second circulation operation are sequentially executed. Even when the pump 86 is stopped, the ink in the sub tank 80 can be supplied to the reservoir unit 71 through the ink supply pipe 82.

  When the first circulation operation is started, as shown in FIG. 7A, the control device 16 opens the first valve 87 and closes the second valve 88, and then drives the pump 86. As a result, the ink stored in the outflow chamber 53 of the sub tank 80 is forcibly supplied to the ink inflow passage 72 via the ink supply pipe 82. At this time, since the first valve 87 is open, the flow path resistance in the path from the ink inflow path 72 through the first exhaust path 73 and the first ink return pipe 83 to the sub tank 80 is reduced. It becomes smaller than the flow path resistance of the path from the path 72 to each discharge port via the ink outflow path 75 and the common ink chamber. For this reason, the ink supplied to the ink inflow passage 72 does not flow into the ink outflow passage 75 but sequentially passes through the first exhaust passage 73 and the first ink return pipe 83 and enters the inflow chamber 51 of the sub tank 80. The returning first ink circulation is performed. By performing the first ink circulation, bubbles staying in the ink inflow passage 72, particularly bubbles staying on the filter 75 a, together with the ink, the first exhaust passage 73 and the first ink return pipe 83. Are sequentially trapped in the sub tank 80.

  Note that when the first ink circulation is performed, the ink pressure in the ink inflow channel 72 and the first exhaust channel 73 is higher than that during printing. The resin film 78 of the first exhaust flow path 73 is in close contact with the restriction member 79 while being in close contact with the restriction member 77. When the first ink circulation is performed for a predetermined time, the control device 16 stops the pump 86 and then closes the first valve 87. Thus, the first circulation operation is completed.

  Subsequently, when the second circulation operation is started, the control device 16 drives the pump 86 after closing the first valve 87 and opening the second valve 88 as shown in FIG. 7B. Accordingly, the ink stored in the outflow chamber 53 of the sub tank 80 is forcibly supplied to the common ink chamber of the head body 2 through the ink supply pipe 82, the ink inflow channel 72, and the ink outflow channel 75. At this time, since the second valve 88 is open, the flow path resistance in the path from the common ink chamber to the sub tank 80 via the second exhaust flow path 74 and the second ink return pipe 84 is different from the common ink chamber. It becomes smaller than the flow path resistance of the path that reaches the discharge port via the individual ink flow path. For this reason, the ink supplied to the common ink chamber passes through the second exhaust flow path 74 and the second ink return pipe 84 in order without returning to the individual ink flow paths, and returns to the ink inflow chamber 51 of the sub tank 80. The second ink circulation is performed. By performing the second ink circulation, the air bubbles staying in the ink outflow passage 75 and the common ink chamber sequentially pass through the second exhaust passage 74 and the second ink return pipe 84 together with the ink to the sub tank 80. Be trapped.

  When the second ink circulation is performed, the ink pressure in the ink inflow channel 72 is increased, and the resin film 76 in the ink inflow channel 72 is in close contact with the regulating member 77. When the second ink circulation is performed for a predetermined time, the control device 16 stops the pump 86 and then closes the second valve 88. Thus, the second circulation operation is completed.

  The ink flow in the storage chamber 50 of the sub tank 80 will be described with reference to FIG. As shown in FIG. 3, the ink returned from the reservoir unit 71 flows into the inflow chamber 51 from the inflow port 83a through the first ink return tube 83, and from the inflow port 84a through the second ink return tube 84. It flows into the inflow chamber 51. The ink that flows in from the inflow ports 83 a and 84 a flows so as to be reversed along the inner wall surface of the inflow chamber 51, then passes through the slit 61 and flows into the internal flow path 52. The ink that has flowed into the internal flow path 52 from the slit 61 reaches the slit 62 while bending the flowing direction by the wall body 63. The ink that has flowed in from the inflow ports 83 a and 84 a includes bubbles that have stayed in the inkjet head 1. In the process in which the ink flowing in from the inflow ports 83a and 84a passes through the inflow chamber 51 and the internal flow path 52 and reaches the slit 62, bubbles contained in the ink reach the liquid surface and disappear, and are separated from the ink. The The ink from which the bubbles are separated flows from the slit 62 into the outflow chamber 53.

  On the other hand, ink from the ink tank 90 flows into the internal flow path 52 from the supply port 81a. The ink that has flowed in from the supply port 81a reaches the slit 62 together with the ink that has flowed in from the inflow ports 83a and 84a. Since the ink from the ink tank 90 does not contain bubbles, the outflow chamber 53 stores ink that does not contain bubbles. The ink stored in the outflow chamber 53 flows out from the outflow port 82 a to the ink supply pipe 82 and is supplied to the reservoir unit 71.

  As described above, according to the inkjet printer 101 of the present embodiment, the ink inflow direction of the inflow ports 83a and 84a formed in the inflow chamber 51 of the sub tank 80 is the center of the inflow ports 83a and 84a when viewed from the direction of gravity. A direction toward the inner wall surface of the inflow chamber 51 on the opposite side of the slit 61 with respect to the straight lines Y1 and Y2 orthogonal to the straight lines X1 and X2 connecting the center of the slit 61 and passing through the centers of the inflow ports 83a and 84a. Therefore, the ink that has flowed in from the inflow ports 83 a and 84 a flows so as to be reversed along the inner wall surface of the inflow chamber 51, and then reaches the slit 61. For this reason, it is possible to secure a time for separating the bubbles contained in the ink from the ink by increasing the path length of the ink from the inflow port to the first connection port. Accordingly, bubbles contained in the ink can be efficiently separated with a simple structure.

  In addition, the inflow channel 68b for allowing ink to flow into the inflow chamber 51 of the sub tank 80 extends obliquely upward toward the inner wall surface of the inflow chamber 51, and has an inflow port 84a at the upper end thereof. In the inflow channels 68a and 68b, the bubbles contained in the ink can be quickly moved to the water surface. Thereby, bubbles contained in the ink can be more efficiently separated.

  Further, guide walls 67a and 67b formed on the bottom surface of the inflow chamber 51 guide the ink flowing into the inflow chamber 51 from the inflow ports 83a and 84a so as to surely flow in the ink inflow direction. The path length of the ink leading to the connection port can be reliably increased.

  In addition, since the wall 63 that bends the ink flow path is formed in the internal flow path 52, the ink path length of the internal flow path 52 can be further increased.

  Moreover, the recessed corner | angular part of the wall bodies 63 and 64 is formed in the curved surface. Thereby, it is suppressed that a bubble stays in the recessed corner | angular part of wall body 63,64.

  Furthermore, a wall body 64 that extends downward from the upper surface of the upper lid 80 b is disposed in the internal flow path 52 so as to follow a portion of the wall body 63 that separates the internal flow path 52 and the outflow chamber 53. . As a result, the ink in the internal flow path 52 is prevented from flowing over the wall body 63 and into the outflow chamber 53. In addition, the ink path length can be reliably increased.

  In addition, since the liquid level sensor 80c is disposed in the outflow chamber 53 in which the ink from which bubbles are separated is stored, the liquid level sensor 80c can accurately detect the height of the liquid level of the ink.

<Modification>
In this embodiment, the ink inflow direction of the inflow ports 83a and 84a is a direction perpendicular to the lower inner wall surface in FIG. 3 in the inflow chamber 51 when viewed from the direction of gravity. However, the present invention is not limited to this. Is not to be done. The ink inflow direction is relative to the straight lines Y1 and Y2 orthogonal to the straight lines X1 and X2 connecting the centers of the inlets 83a and 84a and the center of the slit 61 as viewed from the direction of gravity and passing through the centers of the inlets 83a and 84a. As long as the direction is toward the inner wall surface of the inflow chamber 51 on the side opposite to the slit 61, the other direction may be used. If the ink inflow direction satisfies the above-described conditions, the ink flowing from the inflow port reaches the slit 61 after flowing so as to be reversed along the inner wall surface of the inflow chamber 51, so that the ink path length is increased. Thus, it is possible to secure time for the bubbles contained in the ink to separate from the ink.

  For example, as shown in FIG. 8, the ink inflow directions at the inlets 183a and 184a may be diagonally downward to the right toward the lower inner wall surface in FIG. At this time, since the ink flowing in from the respective inlets 183a and 184a flows so as to be reversed in the same direction (counterclockwise in FIG. 8) along the inner wall surface of the inflow chamber 51, each ink reaches the slit 61. Collisions between the inks flowing in from the inflow ports 183a and 184a can be suppressed. As a result, the ink that has flowed in from the respective inlets 183a and 184a can be smoothly flowed while increasing the path length.

  Furthermore, from the viewpoint of increasing the ink path length, as shown in FIG. 9, a straight line extending from the center of the inflow port 283a in the ink inflow direction from the inflow port 283a to the inflow chamber 51 as seen from the gravity direction. 9 and the inner wall surface on the left side in FIG. 9 of the inflow chamber 51, the angle θ1 formed by the direction approaching the center of the slit 61 along the inner wall surface from the intersection point and the ink inflow direction may exceed 90 degrees. It may be. Similarly, at the intersection of a straight line extending from the center of the inlet 284a in the ink inflow direction from the inlet 284a to the inlet chamber 51 and the inner wall surface of the inlet chamber 51 in the upper part of FIG. The angle θ2 formed by the direction approaching the center of the slit 61 along the ink inflow direction may exceed 90 degrees.

  According to this, ink that has flowed in from the inlets 283a and 284a collides with the inner wall surface of the inflow chamber 51 and then flows in a direction away from the slit 61 along the inner wall surface. Therefore, the ink that has flowed in from the inlets 183a and 184a reaches the slit 61 after flowing so as to be reversed along the inner wall surface of the inflow chamber 51 in the same direction (counterclockwise in FIG. 9). Accordingly, it is possible to secure a time for the bubbles contained in the ink to be separated from the ink by increasing the ink path length. In addition, the collision between the inks flowing in from the respective inlets 283a and 284a can be suppressed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. In the above-described embodiment, the inflow channel 68 b that allows ink to flow into the inflow chamber 51 of the sub tank 80 extends obliquely upward toward the inner wall surface of the inflow chamber 51, but the inflow channel is vertical. It may extend in the direction, or may extend horizontally or downward.

  In the above-described embodiment, the guide walls 67a and 67b for guiding the ink flowing into the inflow chamber 51 from the inflow ports 83a and 84a in the ink inflow direction are formed on the bottom surface of the inflow chamber 51. 67a and 67b may not be formed.

  Furthermore, in the above-described embodiment, the wall 63 is configured to bend the ink flow path in the internal flow path 52, but the ink flow path may not be bent in the internal flow path. Good.

  In addition, in the above-described embodiment, the concave corners of the walls 63 and 64 in the internal flow path 52 are formed as curved surfaces, but the concave corners of the walls may be formed as flat surfaces.

  Further, in the above-described embodiment, the wall body extends downward from the upper surface of the upper lid 80b so as to follow the portion of the wall body 63 that separates the internal flow path 52 and the outflow chamber 53 from the internal flow path 52. 64 is disposed, but a wall body extending downward from the upper surface of the upper lid 80b may be disposed along the other part of the wall body 63, or such a wall body is not disposed. May be.

  Further, in the above-described embodiment, the reflection type optical liquid level sensor 80 c is disposed in the outflow chamber 53, but other liquid levels capable of detecting the liquid level of the ink stored in the outflow chamber 53 are also provided. The liquid level sensor of the type may be disposed in the outflow chamber 53, or the liquid level sensor may not be disposed in the outflow chamber 53. In this case, it is preferable that the liquid level sensor is arranged at other places such as the inflow chamber 51 and the internal flow path 52.

  In the above-described embodiment, the supply port 81 a for supplying ink from the ink tank 90 is formed in the internal flow path 52, but the supply port is formed in the inflow chamber 51 or the outflow chamber 53. May be.

  In addition, in the above-described embodiment, the two inflow ports 83a and 84a into which the ink from the ink jet head 1 flows are formed in the inflow chamber 51. However, according to the configuration of the ink jet head, 1 or Three or more inflow ports may be formed.

  The present invention is also applicable to a liquid tank that stores liquids other than ink.

DESCRIPTION OF SYMBOLS 1 Inkjet head 10 Ink supply unit 50 Storage chamber 51 Inflow chamber 52 Internal flow path 53 Outflow chamber 61, 62 Slit 63, 64 Wall body 66a, 66b Protrusion 67a, 67b Guide wall 68a, 68b Inflow flow path 80 Sub tank 80a Case 80b Upper lid 80c Liquid level sensor 81 Ink supply tube 81a Supply port 82 Ink supply tube 82a Outlet 83 Ink return tube 83a, 183a Inlet 84 Ink return tube 84a, 184a Inlet 90 Ink tank 101 Inkjet printer

Claims (10)

A storage chamber for storing liquid;
An inflow passage for allowing liquid to flow into the storage chamber from an inlet opening in the storage chamber;
An outflow passage through which liquid flows out of the storage chamber from an outlet opening in the storage chamber;
An inflow chamber having an opening at the inlet is formed as a part of the storage chamber in the storage chamber, and the inflow chamber communicates with the remaining portion of the storage chamber through a first connection port,
When viewed from the direction of gravity, the inflow direction of the liquid from the inlet to the storage chamber is orthogonal to a straight line connecting the center of the inlet and the center of the first connection port and passes through the center of the inlet. A liquid tank, wherein the liquid tank is in a direction toward an inner wall surface of the inflow chamber on a side opposite to the first connection port with respect to a straight line. A storage chamber for storing liquid;
An inflow passage for allowing liquid to flow into the storage chamber from an inlet opening in the storage chamber;
An outflow passage through which liquid flows out of the storage chamber from an outlet opening in the storage chamber;
An inflow chamber having an opening at the inlet is formed as a part of the storage chamber in the storage chamber, and the inflow chamber communicates with the remaining portion of the storage chamber through a first connection port,
When viewed from the direction of gravity, at the intersection of a straight line that passes through the center of the inlet and extends in the liquid inflow direction from the inlet to the storage chamber and the inner wall surface of the inlet chamber, the intersection points to the inner wall surface. An angle formed by a direction approaching the center of the first connection port along the inflow direction and the inflow direction is more than 90 degrees.   3. The liquid according to claim 1, wherein the inflow channel extends upward from below in the direction of gravity in the inflow chamber, and has the inlet at an upper end. tank.   The liquid tank according to claim 1, wherein a guide wall that guides the liquid that has flowed into the inflow chamber from the inflow port in the inflow direction is formed in the inflow chamber. The remaining part of the storage chamber is further formed with an internal flow path communicating with the inflow chamber through the first connection port,
A first wall body extending upward from the bottom surface of the storage chamber, which forms a wall portion of the internal flow path in the internal flow path and bends the flow path of the liquid in the internal flow path. The liquid tank according to claim 1, wherein the liquid tank is formed.   The liquid tank according to claim 5, wherein the concave corner portion of the first wall body is formed by a curved surface.   The second wall body extending downward from the upper surface of the storage chamber is formed in the internal flow path along at least a part of the first wall body. The liquid tank according to 5 or 6.   The liquid tank according to claim 7, wherein the recessed corner portion of the second wall body is formed of a curved surface. A supply port for supplying a liquid to the internal flow path is formed,
The liquid tank according to any one of claims 5 to 8, wherein at least a part of the liquid flowing out from the outflow port flows in from the inflow port. An outflow chamber in which the outflow port is formed is further formed in the storage chamber as a part of the storage chamber, and the outflow chamber and the internal flow path communicate with each other through the second connection port. And
The liquid tank according to any one of claims 1 to 9, wherein a liquid level sensor that detects a height of a liquid level in the outflow chamber is disposed in the outflow chamber.

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