JP2007261161A - Ink supply unit of inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink supply unit of an inkjet recording device capable of shortening the time needed for ink circulation without enlarging the recording device. <P>SOLUTION: The ink supply unit includes a sub tank 5 holding an ink supplied to a recording head and a main tank 130 holding an ink supplied to the sub tank 5 and arranged above the sub tank 5. Further, the ink supply unit includes a pump section 50 pumping the ink from the main tank 130 to the sub tank 5. The inside of the main tank 130 and the inside of the sub tank 5 communicate with each other through supplying needles 321, 322. A piston section 51 is arranged in the pump section 50 such that the ink supplying needle 321 can be connected to and separated from a holding port 10b. The piston 51 and the end portion of an extending communication path formed in a piston base 55 are positioned in the lower side of the holding port 10c of the end portion side of the ink supplying needle 322 when the piston 51 is connected with the holding port 10b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink supply unit of an ink jet recording apparatus that records an image by ejecting ink onto a recording medium such as recording paper.

  7 is an external perspective view of a conventional ink jet recording apparatus, and FIG. 8 is a perspective view showing a state in which the upper cover of the ink jet recording apparatus shown in FIG. 7 is removed.

  7 and 8, a roll holder unit 122 that can be opened and closed to the front surface is provided on the front surface of the ink jet recording apparatus, and a recording medium such as recording paper is supplied from the roll holder unit 122 to the recording unit. The ink jet apparatus includes an apparatus main body 190 supported by two legs 180, a stacker 123 on which a recording medium such as discharged recording paper is stacked, and a transparent, openable and closable upper cover 121. Yes. A recovery unit 300 and a supply unit 320 that holds the main tank 130 are disposed on the right side of the apparatus main body 100 in the figure.

  As shown in FIG. 8, the ink jet recording apparatus has a pair of conveying rollers 110 for conveying a recording medium such as recording paper in the direction of arrow A (sub-scanning direction). Further, the ink jet recording apparatus includes a carriage 200 that is guided and supported so as to be able to reciprocate in the width direction (arrow B direction, main scanning direction) of the recording medium, and a carriage motor (not shown) for reciprocating the carriage 200 in the arrow B direction. ) And belt transmission means 270. A recording head 201 as a recording unit attached to the carriage 200 is attached to the carriage 200. The ink jet recording apparatus further includes a supply unit 320 that applies an appropriate negative pressure to hold a meniscus at an ejection port (not shown) of the recording head 201 and holds the ink tank 130. Here, the negative pressure means a negative pressure due to a water head difference between the recording head 201 and the supply unit 320. The ink jet recording apparatus further includes a recovery unit 300 that performs suction-type head cleaning for eliminating ink discharge defects caused by clogging of the discharge ports of the recording head 201.

  In the case of the illustrated ink jet recording apparatus, a plurality of recording heads 201 are mounted on the carriage 200 in order to perform color recording on a recording medium. The plurality of recording heads 201 includes, for example, six recording heads 201 corresponding to different colors of ink. For example, a head for Y (yellow), a head for M (magenta), a head for C (cyan), a head for Bk (black), a head for light C (light color cyan), and a head for light M (light color magenta) This is the recording head 201. These recording heads 201 are connected to the supply unit 320 by supply tubes 335 (each color is separate), and recording is possible when ink is sent to the recording head 201. Further, all of the supply tubes 335 are bundled together by a guide 260 so that the supply tubes 335 are not scattered and do not hit other members when the carriage 200 reciprocates.

  With the above configuration, when recording on a recording medium such as recording paper, after the recording medium is transported to a predetermined recording start position by the transport roller pair 110, main scanning by the recording head 201 and sub scanning by the transporting roller 110 are performed from here. Is repeated. Thereby, recording on the entire recording medium is performed. That is, the carriage 200 is moved in the direction of arrow B in FIG. 8 by the carriage belt 270 and a carriage motor (not shown), and recording is performed on the recording medium. When the carriage 200 is returned to the position before the main scanning, the recording medium is conveyed in the sub-scanning direction (the direction of arrow A in FIG. 8) by the conveying roller pair 110, and then the carriage is again moved in the direction of the arrow B in FIG. 200 main scans are performed. As a result, images, characters, etc. are recorded on the recording medium. When the above operation is repeated and the recording for one sheet of recording medium is completed, the recording medium is discharged into the stacker 123, and the recording for one sheet is completed. The recording medium includes recording paper, plastic thin plate, cloth, or the like.

  Next, the configuration of the ink supply system of the ink jet recording apparatus will be described with reference to FIG. FIG. 9 shows an ink flow path of the ink jet recording apparatus shown in FIG. 8, and only the flow path for one color is shown for ease of explanation. The configuration of the ink supply system shown in FIG. 9 is disclosed in Patent Document 1.

  Reference numeral 201 denotes a recording head, and a head connecting portion provided at the tip of the supply tube 335 is connected to the insertion port 201 a of the recording head 201. The insertion port 201a is connected to a liquid chamber 201f described later. The liquid chamber 201f is connected to a nozzle portion having a plurality of nozzles 201g, and supplies ink directly to the nozzles 201g. Therefore, the ink from the insertion port 201a is supplied to the nozzle 201g. Needless to say, the space from the insertion port 201a to the nozzle 201g is kept airtight with respect to the atmosphere.

  The nozzles 201g are arranged with the front end (ejection port) for ejecting ink facing downward, and the ink fills the nozzle 201g with a meniscus formed at the ejection port. For this reason, the inside of the recording head 201, particularly the inside of the liquid chamber 201f, is maintained at a negative pressure with respect to the atmospheric pressure. However, if the negative pressure is too small, when foreign matter or ink adheres to the tip of the nozzle 201g, the meniscus at the ink discharge port may be broken and the ink may leak out of the nozzle 201g. On the other hand, if the negative pressure is too large, the force that pulls the ink into the nozzle 201g (inside the liquid chamber 201f) becomes stronger than the energy given to the ink during ejection, resulting in ejection failure. Therefore, the negative pressure in the liquid chamber 201f is kept in a certain range that is slightly lower than the atmospheric pressure. The range of the negative pressure varies depending on the number of nozzles 201g, the cross-sectional area, the performance of the heating resistor element, and the like, but generally the range of −20 mmAq to −200 mmAq is preferable.

  In the illustrated example, as a method for setting the inside of the recording head 201 to the negative pressure described above, the recording head 201 is disposed at a position higher than the supply unit 320 and both are connected by a supply tube 335, and the negative pressure is caused by the water head difference. The method of generating is taken.

  Next, the supply unit 320 and the main tank 130 will be described. The main tank 130 is detachable from the supply unit 320, and has an ink supply port sealed with a rubber plug 130b and an air introduction port sealed with a rubber plug 130c at the bottom. On the other hand, the supply unit 320 includes an ink supply needle 321 for taking out ink from the main tank 130 and an air introduction needle 322 for introducing air into the main tank 130. Both the ink supply needle 321 and the air introduction needle 322 are hollow needles, and are arranged with the needle points upward corresponding to the positions of the ink supply port and the air introduction port of the main tank 130. When the main tank 130 is attached to the supply unit 320, the ink supply needle 321 and the air introduction needle 322 penetrate the rubber plugs 130b and 130c, respectively, and enter the main tank 130.

  The ink supply needle 321 is connected to the supply tube 335 through the liquid path 323, the supply valve 325, and the liquid path 327. The air introduction needle 322 communicates with the atmosphere via the liquid path 328, the buffer chamber 330, and the atmosphere communication port 329.

  The supply valve 325 includes a diaphragm 325a made of a rubber material, and the two liquid passages 327 and 323 are shielded and opened by displacing the diaphragm 325a. A spring holder 325b that holds a pressing spring 325c is attached to the upper surface of the diaphragm 325a. The diaphragm 325a is crushed by the pressing spring 325c to shield the liquid passages 327 and 323 from each other. The operation of the supply valve 325 is performed by transmitting (rotating) the driving force of the motor 325e to the cam 325f via a gear train (not shown). The lever 325d is operated by the rotation of the cam 325f and the spring holder 325b is lifted against the spring force of the pressing spring 325c, so that the liquid paths 327 and 323 communicate with each other. The supply valve 325 is opened when the recording head 201 is discharging ink, and is shielded during standby and rest.

  The configuration of the supply unit 320 described above is provided for each ink color.

  With the above configuration, when ink in the recording head 201 is consumed, the negative pressure causes ink to be supplied from the main tank 130 to the recording head 201 via the supply unit 320 and the supply tube 335 as needed. At this time, the same amount of air as the ink supplied from the main tank 130 is introduced into the main tank 130 from the atmosphere communication port 329 through the buffer chamber 330 and the air introduction needle 322.

  The ink supply system configuration as described above has a disadvantage that the main tank 130 cannot be freely replaced during the recording operation. This is because if the main tank 130 is removed, the connection with the above-described buffer tank 330 that applies an appropriate negative pressure to the recording head 201 (fluid connection of ink) is disconnected, and an appropriate negative pressure is applied to the recording head 201. It is because it becomes impossible to be given.

  Therefore, when replacing the main tank 130, there is no choice but to wait until the recording operation is completed and the recording apparatus is in a standby state. This waiting time naturally varies depending on the recording area, recording density, recording mode, and the like. In particular, in a large-format inkjet recording apparatus (about A2 size), the recording area is several to several tens of times that of a small-format inkjet recording apparatus (about A3 size), and the recording time is also reduced to the recording area. It will be several to several tens of times in proportion. Therefore, in a large-format inkjet recording apparatus, it is not uncommon for the recording time to exceed well over several tens of minutes. In particular, when long recording is performed, the recording time becomes the longest. Thus, the fact that the main tank 130 cannot be freely replaced during the recording operation means that the user has to wait for this waiting time, which is troublesome.

  In order to solve this problem, as shown in FIG. 10, Patent Document 2 discloses an apparatus having a configuration in which a sub tank 330 ′ is provided instead of the buffer tank 330 in the configuration of FIG. 9 and a main tank 130 is disposed above the sub tank 330 ′. Has been. This configuration is of a type called a bird's water tank (chicken feed). In this type of configuration, when the liquid level of the sub tank 330 ′ falls, the air flows backward from the ink supply port of the main tank 130, and the ink corresponding to the amount of air falls to the sub tank 330 ′ to keep the liquid level of the sub tank 330 ′ constant. To. According to this configuration, the main tank 130 can be replaced even during the recording operation, and when the main tank 130 is removed, recording is performed with the ink in the sub tank 330 '.

  In addition, the ink in the ink tank 130 and the sub tank 330 ′ may become non-uniform in ink concentration due to precipitation of pigment particles in the solvent over time. Therefore, when recording is performed on a recording medium, density unevenness may occur and recording failure may occur.

  Therefore, as shown in FIG. 11, a pump part P is provided between the ink tank 130 and the sub tank 330 ′, and the ink is circulated and stirred between the ink tank 130 and the sub tank 330 ′ to precipitate the pigment particles. A configuration has been devised that prevents the ink density and makes the ink density uniform. In the configuration shown in FIG. 11, the ink is forced to flow in the direction of arrow A by the pump unit P, so that the pressure in the ink tank 130 becomes negative and the ink circulates in the direction B.

  FIG. 12 is a sectional view of the pump unit shown in FIG. With reference to FIG. 12, the above-described chicken feed and ink circulation will be described.

  First, the chicken feed will be described.

  When the main tank 130 is attached to the sub-tank 330 ′ that is not filled with ink, a small amount of ink in the main tank 130 is guided into the ink supply needles 321 and 322, and the ink supply needles 321 and 322 are filled with the ink. It is. At the same time, the cylinder 500 is filled with ink through the hole 510 a of the piston 510. Then, a water head difference h is generated between the lower end portion of the cylinder 500 and the lower end portion of the supply needle 322, and the ink in the main tank 130 falls by its own weight into the sub tank 330 ′ due to the water head difference h (ink having a low water head). It falls by its own weight from the supply needle 321). Needless to say, it is desirable to make the water head difference h as large as possible in order to stabilize the fall of the dead weight. Then, the amount of ink falling from the ink supply needle 321 causes a negative pressure in the main tank 130, air enters through the ink supply needle 322, and the ink level in the sub tank 330 'rises. In this way, when the ink liquid level in the sub tank 330 ′ rises from the lower end portion of the cylinder 500, this time, due to the water head difference between the ink liquid level and the lower end portion of the supply needle 322, the ink liquid drops. When the ink liquid level reaches the lower end of the ink supply needle 322, the water head difference disappears, the ink falls by its own weight, and the liquid level of the sub tank 330 'is kept constant.

  Next, ink circulation for ink precipitation prevention stirring will be described.

  The piston 510 slides in the cylinder 500 and reciprocates up and down. When the piston 510 moves from the uppermost position to the lowermost position, the check valve 520 (elastic body) receives the hydraulic pressure and closes the hole 510a. Then, the inside of the cylinder 500 becomes negative pressure, and the ink in the main tank 130 enters the cylinder 500 through the ink supply needle 321 by the action of the negative pressure. Conversely, when the piston 510 moves from the lowermost position to the uppermost position, the hole 510a is opened by receiving the hydraulic pressure from the hole 510a. As a result, the cylinder 500 does not have a positive pressure, so that the ink in the sub tank 330 ′ does not flow back to the main tank 130 via the ink supply needle 321.

  Such vertical movement of the piston 510 is repeated, and the ink in the main tank 130 is guided into the sub tank 330 ′. As a result, the main tank 130 has a negative pressure corresponding to the amount of ink introduced, air enters through the ink supply needle 322 (gas-liquid exchange), and the ink liquid level in the sub tank 330 'rises. When the ink level reaches the lower end portion of the ink supply needle 322, the ink in the sub tank 330 ′ is guided into the main tank 130 via the ink supply needle 322, and the space between the sub tank 330 ′ and the main tank 130 is reached. Ink circulates.

By performing the ink circulation in this way, the ink in which pigment particles or the like are precipitated in the sub tank 330 ′ and the main tank 130 is stirred, and the ink density can be made uniform.
Japanese Patent Application Laid-Open No. 2002-248777 Japanese Patent Laying-Open No. 2004-174815 (FIG. 7)

  However, the ink supply system configuration (FIGS. 11 and 12) of the ink jet recording apparatus described above has a problem that the volume of the pump cylinder 500 cannot be increased. In order to improve the stirring effect, it is essential to improve the pump capacity in order to improve the ink circulation efficiency, and the fact that the volume of the pump cylinder 500 cannot be increased hinders the improvement of the pump capacity. The reason why the volume of the pump cylinder 500 cannot be increased is as follows. That is, if the inside of the pump cylinder 500 is not filled with a small amount of ink that flows when the main tank 130 is attached to the sub tank 330 ′ in a state where no ink is contained, no chicken head difference is generated, so chicken feed is not performed. Therefore, the volume of the pump cylinder 500 can only be set to the above minute capacity. This small amount of ink varies depending on various design conditions and ink physical properties. For example, the ink supply needle 321 has a diameter of 0.8 mm, a length of 30 mm, ink physical properties of surface tension η of 9 mP, viscosity γ of 72 dyn / cm, and main tank 130 capacity of 100 ml. Then, a very small amount of ink is about 0.5 to 1 ml. Therefore, since the volume of the cylinder 500 can only be set to about 0.5 ml, the pump capacity is remarkably lowered, and this requires a considerable time for ink circulation for stirring.

  On the other hand, it is also conceivable to improve the pumping capacity while securing the chicken feed performance by arranging the pump part P below the lower limit of the water head difference h, that is, below the lower end part of the cylinder 500. . However, since the pump part P is disposed below the sub-tank 330 ', the configuration of the sub-tank 330' increases, which leads to an increase in the size of the recording apparatus, which is not preferable.

  Therefore, an object of the present invention is to provide an ink supply unit of an ink jet recording apparatus that can reduce the time required for ink circulation without increasing the size of the recording apparatus.

  An ink supply unit of an ink jet recording apparatus of the present invention stores a sub tank that stores ink to be supplied to a recording head having a discharge port for discharging ink, and stores ink to be supplied to the sub tank, and is disposed above the sub tank. And a main tank. The ink supply unit further includes a pump unit that pumps ink from the main tank to the sub tank. The inside of the main tank and the inside of the sub tank are configured to be able to communicate with each other via first and second communication passages having end portions that terminate in the sub tank. The pump part is provided with an extended communication path extending from the first communication path so as to be connected to and disconnected from the end of the first communication path. When the extended communication path is connected to the end of the first communication path, the end of the extended communication path opposite to the end connected to the end of the first communication path is And located below the end of the second communication path.

  According to the present invention, it is possible to provide an ink supply unit of an ink jet recording apparatus that can reduce the time required for ink circulation without increasing the size of the recording apparatus.

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

  FIG. 1 is a diagram illustrating a configuration of an ink flow path of an ink jet recording apparatus according to an embodiment of the present invention. 2 is a cross-sectional view of the sub-tank shown in FIG. 1, FIG. 3 is an enlarged view of the pump unit shown in FIG. 1 in the uppermost position, and FIG. 4 is the pump unit shown in FIG. It is an enlarged view in a state. 5 is a component diagram of the pump section shown in FIG. 1, and FIG. 6 is a partial detail view of the pump section shown in FIG.

  1 to 6 schematically show only ink channels for one color as in the prior art. The flow path configuration between the recording head 201 and the sub-tank 5 (including the supply valve 325) is the same as that of the prior art, so the description is omitted. I will omit the explanation.

  First, the sub tank in this embodiment is demonstrated with reference to FIGS.

  The sub tank 5 in the present embodiment includes a sub tank cover 15 formed in a bowl shape so as to store ink therein, and a sub tank base 10 as a lid thereof. The sub-tank cover 15 and the sub-tank base 10 are joined by sandwiching a not-shown packing (for example, rubber) between them, thereby preventing ink leakage from the joint.

  The sub tank cover 15 includes an atmosphere port 15 b for opening the inside to the atmosphere, and a connection port 15 a for connecting to the supply valve 325.

  The sub tank base 10 includes holding ports 10b and 10c for holding the ink supply needles 321 and 322. Below the ink supply needle 321, there is provided a pump cylinder portion 10 a having a cylindrical shape (hollow inside), which is an element of the pump portion 50 described later. The ink supply needle 321 forms a first communication path that connects the main tank 130 and the sub tank 5, and the ink supply needle 322 forms a second communication path that connects the main tank 130 and the sub tank 5.

  The piston 51 has a through hole that is an extended communication path formed therein. The through hole is connected to a through hole of a piston base 55 described later to form an extended communication path that extends the first communication path formed of the ink supply needle 321. That is, this extended communication path is formed inside the piston portion including the piston 51 and the piston base 55. The piston 51 is slidable in the pump cylinder part 10a and is driven in the vertical direction (C direction in FIG. 3) by a drive part (not shown). The seal cap 52 is formed of an elastic body such as rubber, and is attached to the piston 51 by press-fitting. The seal cap 52 seals the lower portion of the holding port 10 b that is a holding portion of the ink supply needle 321 and seals the piston 51 at the uppermost position of the piston 51. When the lower portion of the holding port 10 b and the piston 51 are both sealed by the seal cap 52, the holding port 321 of the ink supply needle 321 communicates with the seal cap 52, the through hole of the piston 51, and the through hole of the piston base 55. The sealing by the seal cap 52 is performed by the biasing force of the seal spring 54. The check valve 53 is attached to the piston base 55 so as to be movable in the vertical direction, and opens and closes the through hole of the piston base 55 using the hydraulic pressure of ink. The piston base 55 has a through hole connected to the through hole of the piston 51 as described above, and is configured to hold the piston 51. The piston base 55 is connected to a drive unit (not shown), and the piston base 55 is moved in the same direction by moving the piston base 55 in the vertical direction (direction C in FIG. 3) by the drive unit.

  Next, the chicken feed (replenishment of ink weight from the main tank 130 to the sub tank 5) according to the above configuration will be described.

  When performing the chicken feed, the piston 51 is controlled to be disposed at the uppermost position (position in FIG. 3). The control is performed when the control unit (not shown) of the main body of the recording apparatus stops driving the drive unit when it is detected by the photosensor and the sensor flag (not shown) that the piston 51 is at the uppermost position. . In this uppermost position, the check valve 53 is set in a positional relationship such that it comes into contact with the lower end of the pump cylinder portion 10a and the through hole of the piston base 55 is always opened.

  First, a state where the sub tank 5 is not filled with ink (device initial state) will be described.

  When the ink supply needles 321 and 322 on the sub tank 5 side are inserted into the main tank 130 and the main tank 130 is attached to the sub tank 5, a small amount of main tank 130 ink enters the ink supply needles 321 and 322, and the ink supply needle 321. , 322 are filled with ink. At this time, the piston 51 is connected to the lower end portion of the holding port 10 b of the sub tank base 10 via the seal cap 52. As a result, the ink supply needle 321 that is the first communication portion is connected to the extended communication portion including the through hole of the piston 51 and the through hole of the piston base 55, and the extended communication portion is also filled with ink. When this connection is made, the lower end portion of the extended communication portion (the lower end portion of the through hole of the piston base 55) is positioned below the lower end portion of the holding port 10c on the ink supply needle 322 side which is the second communication path. To do.

  The volume of the extended communication path is set to 0.17 ml (diameter is φ3 mm, height is 24 mm), and can be sufficiently filled even with a small amount of ink (about 0.5 ml). Further, the flow resistance of the extended communication path is set to be smaller than the flow resistance of the ink supply needle 321 that is the first communication portion.

  When the extended communication path is filled with ink, a water head difference h (see FIG. 2) occurs between the lower end portion of the extended communication path and the lower end portion of the supply needle 322, and the ink in the main tank 130 is transferred to the sub tank 5 by the water head difference h. It falls by its own weight (it falls by its own weight from the ink supply needle 321 having a low water head). Needless to say, it is desirable to make the dimension of the head difference h as large as possible in order to stabilize this falling of its own weight.

  Then, the amount of ink falling from the ink supply needle 321 causes a negative pressure in the main tank 130, and air enters the main tank 130 through the ink supply needle 322. In this way, gas-liquid exchange is performed between the main tank 130 and the sub tank 5, and the ink liquid level in the sub tank 5 rises. Note that when the ink liquid level in the sub tank 5 is lower than the lower end portion of the through hole of the piston base 55, air also enters from the ink supply needle 321.

  In this way, when the ink liquid level in the sub tank 5 rises from the lower end portion of the through hole of the piston base 55, the ink falls by its own weight due to the water head difference between the ink liquid surface and the lower end portion of the ink supply needle 322. To go. For example, when the ink level is at position F in FIG. 2, the ink falls by its own weight due to the water head difference h '. When the ink liquid level reaches the position E in FIG. 2, there is no difference in water head between the ink liquid level and the lower end portion of the ink supply needle 322, and the ink falls under its own weight.

  Next, the operation of the pump unit 50 (stirring ink circulation) will be described.

  When the piston base 55 is moved downward by a drive unit (not shown) from the state shown in FIG. 3 (the uppermost position), the check valve 53 receives the ink hydraulic pressure upward and closes the through hole of the piston base 55. (See FIG. 6A). Then, the internal space D (see FIG. 3) of the pump cylinder portion 10a above the piston 51 becomes negative pressure, and the negative pressure causes the ink in the main tank 130 to pass through the ink supply needle 321 and the pump cylinder portion 10a. Flows into the interior.

  On the other hand, from the state shown in FIG. 4 (the lowest position), the piston base 55 is moved upward by a drive unit (not shown). At this time, the check valve 53 receives the ink pressure downward and moves to a position where the through hole of the piston base 55 is opened (see FIG. 6B). Therefore, when the piston base 55 is moved upward, no positive pressure is applied to the internal space D (see FIG. 3) of the pump cylinder portion 10a. Therefore, the ink in the sub tank 5 does not flow back to the main tank 130 via the ink supply needle 321 by this operation.

  The ink in the main tank 130 is guided into the sub tank 5 by repeating such up and down movement of the piston 51. Then, the main tank 130 has a negative pressure corresponding to the amount of ink supplied into the sub tank 5, and air enters through the ink supply needle 322. In this way, gas-liquid exchange is performed between the main tank 130 and the sub tank 5, and the ink liquid level in the sub tank 5 rises. When the ink level in the sub tank 5 rises to E (the lower end portion of the ink supply needle 322) in FIG. 2, the ink in the sub tank 5 is now guided into the main tank 130 via the ink supply needle 322. . In this way, the ink circulates again from the main tank 130 to the main tank 130 via the sub tank 5.

  By performing the ink circulation in this way, the ink precipitated in the sub tank 5 and the main tank 130 is stirred, and the ink density can be made uniform. In this embodiment, the volume of the pump cylinder part 10a is about 8 ml (inner diameter is φ20 mm, height is 25 mm), and the pump effective volume can be about 4.5 ml, which is 10 times that of the prior art. The pumping capacity is being improved soon.

  As described above, according to the configuration of the present embodiment, the extension communication path formed in the pump portions 51 and 55 is connected to the ink supply needle 321 that is the first communication path, whereby the main tank 130 to the sub tank 5 is connected. Ink supply by chicken feed becomes possible. Furthermore, with this configuration, the volume of the pump cylinder portion 10a can be increased. Therefore, it is not necessary to arrange the pump part 50 below the lower limit of the water head difference h, that is, below the lower end part of the pump cylinder part 10a. Therefore, it is possible to improve the pumping capacity without increasing the size of the recording apparatus, and the time required for ink circulation can be shortened.

  In this embodiment, the check valve 53 is configured to open and close by the ink hydraulic pressure. However, the check valve 53 is not limited to this, and for example, the check valve 53 uses friction with the cylinder portion 10a. It is good also as a structure which opens and closes interlock | cooperates with operation | movement of pump part 50 itself which opens and closes. Further, in the present embodiment, a piston type configuration has been described as an example of the pump unit 50, but the pump unit 50 is not limited to this, and may be a diaphragm type configuration or the like.

It is a figure which shows the structure of the ink flow path in the inkjet recording device which concerns on one Embodiment of this invention. It is sectional drawing of the subtank shown in FIG. It is an enlarged view in the state where the pump part shown in FIG. 1 exists in the uppermost position. It is an enlarged view in the state in which the pump part shown in FIG. 1 exists in the lowest position. FIG. 2 is a component diagram of the pump unit shown in FIG. 1. FIG. 2 is a partial detail view of a pump unit shown in FIG. 1. It is an external appearance perspective view of the conventional inkjet recording device. It is a perspective view which shows the state which removed the upper cover of the inkjet recording device shown in FIG. It is a figure which shows the ink flow path figure for 1 color of the inkjet recording device shown in FIG. It is a figure which shows the structure of the prior art which supplies ink from a main tank to a sub tank by a chicken feed system. It is a figure which shows the structure of the ink flow path in the inkjet recording device of a prior art. It is a figure which shows sectional drawing of the pump part shown by FIG.

Explanation of symbols

5 Sub tank 10a Pump cylinder part 50 Pump part 51 Piston 52 Seal cap 53 Check valve 55 Piston base 130 Main tanks 321 and 322 Ink supply needle

Claims (5)

A subtank for storing ink to be supplied to a recording head having an ejection port for ejecting ink; a main tank for storing ink to be supplied to the subtank; and disposed above the subtank; and ink from the main tank to the subtank In an ink supply unit of an ink jet recording apparatus having a pump unit for pumping
The inside of the main tank and the inside of the sub tank are configured to be able to communicate with each other via first and second communication paths having end portions that terminate in the sub tank,
The pump part is provided with an extended communication path that extends the first communication path so that it can be connected to and disconnected from the end of the first communication path.
When the extended communication path is connected to the end of the first communication path, the end of the extended communication path opposite to the end connected to the end of the first communication path is An ink supply unit for an ink jet recording apparatus, wherein the ink supply unit is located below the end of the second communication path.   2. The ink supply unit of an ink jet recording apparatus according to claim 1, wherein a flow path resistance of the extended communication path is smaller than a flow path resistance of the first communication path. The pump part has a piston part in which the extended communication path is formed, and a cylinder part in which the piston part can slide,
The ink supply unit of an ink jet recording apparatus according to claim 1, wherein the piston portion is provided with a valve member that opens and closes the opposite end of the extended communication path.   The valve member opens the opposite end portion when the piston portion moves in a direction approaching the end portion of the first communication passage, and the piston portion is the end portion of the first communication passage. The ink supply unit of the ink jet recording apparatus according to claim 3, wherein the opposite end is closed when moving in a direction away from the ink.   The valve member is configured to maintain a state in which the opposite end of the extended communication path is opened when the extended communication path is connected to the end of the first communication path. The ink supply unit of the ink jet recording apparatus according to claim 3 or 4.

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