Liquid supply system and ink jet recording apparatus

The present invention relates to an inkjet recording device that supplies ink from an ink tank to a recording head.

The recording device is widely used as an image forming device having functions such as a printer, a copying machine, and a facsimile, or as an image data output device in a composite electronic device including a computer, a word processor, and a workstation. These recording devices are configured to form images (including characters, symbols, etc.) on recording media such as paper, cloth, plastic sheets, and OHP sheets based on image information. There are two types of recording methods in this recording device: serial type and line type. The serial type is a method of recording an image while alternately repeating a main scan in which the recording head is moved along the recording sheet and a sub-scanning in which the recording sheet is fed at a predetermined pitch. On the other hand, the line type uses a long recording head that extends in the width direction of the recording sheet, so that the image is recorded only by the paper feed (sub-scanning) of the recording sheet while recording one line at a time. It is a method. The recording device can be divided into an inkjet recording device, a thermal transfer recording device, a laser recording device, a heat-sensitive recording device, a wire dot recording device, and the like, depending on the recording method.

The inkjet recording apparatus forms a desired image by flying fine ejection port ink droplets provided on a recording head and landing the ink droplets on a recording medium. Inkjet recording devices have mainly used inks that use dyes. However, recorded materials recorded using inks using dyes have insufficient light resistance and weather resistance, and are not suitable for applications requiring light resistance and weather resistance such as outdoor bulletin prints. Therefore, inks that use pigments instead of dyes are used. On the other hand, since the pigment is not a dissolution system but a dispersion system, in the case of an ink using a pigment, the pigment particles may settle in the ink tank.

Therefore, in particular, in a serial type inkjet recording apparatus that records while moving the recording head, inconvenience is likely to occur in a configuration in which an ink tank containing pigment ink is allowed to stand in the apparatus main body. That is, a pigment precipitation phenomenon that cannot be ignored may occur significantly depending on the frequency of use of the recording device, the interval of use, the number of printed sheets, and the like. Further, in the case of an out-carriage tank in which the ink tanks are individually arranged at positions away from the recording head, the ink capacity may be increased in order to reduce the frequency of tank replacement even for a user who frequently uses the device. Pigment sedimentation sometimes occurred even in a large-capacity tank.

For example, if the ink tank is left attached to the inkjet recording device for a long period of time, the pigment particles gradually settle inside the ink tank. As a result, the concentration of pigment particles is inclined from the bottom to the top inside the ink tank, an excessively dark layer is formed due to the high pigment particle concentration at the bottom, and the pigment particle concentration is low at the top. An overly light layer is created. Then, when the ink is supplied from the ink tank having a structure in which the ink is led out from the bottom of the ink tank, the ink is first supplied from the layer having a high pigment particle concentration, so that an excessively dark printed matter is produced. For this reason, there may be a density difference that is easily visible in the recorded material between the initial stage of use and the latter stage of use of the ink tank.

This phenomenon becomes remarkable in color printing in which an image is formed by shades of color, and techniques for solving such a problem are disclosed in Patent Document 1 and Patent Document 2. These patent documents disclose a technique for providing a tubular pipe having a plurality of holes in the ink tank from the ink supply port of the ink tank. In this technique, when sucking ink, not only the ink is sucked from the portion near the ink supply port inside the ink tank, but the ink is sucked from a large number of places (holes) in the ink tank in the vertical direction. A storage unit is provided to temporarily retain inks of different densities sucked from a plurality of points in the vertical direction. By supplying ink from this storage portion, the ink density is made uniform. It is possible to reduce the density unevenness caused by the sedimentation of the pigment in the ink tank after being left for a long period of time.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-270131</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2001-293880</text></patcit>

<p> However, the stirring process of the pigment ink in the ink tank described in Patent Document 1 and Patent Document 2 is performed by utilizing an operation such as ink suction during the recovery process of the recording device. For example, there is an operation of drawing out the precipitated pigment ink to the outside of the ink tank, a recovery operation when removing air bubbles in the recording head, an operation of filling the recording head with ink, and the like. Each time these operations are performed, the pigment particles are agitated, but the ink in the tank is wasted. In particular, for inks having poor pigment sedimentation characteristics, the stirring operation is repeated many times until the pigment concentration is leveled to a desired level. As a result, a considerable amount of ink is discharged, and the ink that can be originally used for printing is wasted.</p><p> An object of the present invention is to provide an inkjet recording apparatus capable of preventing sedimentation of pigment particles and the like and maintaining a uniform ink density even when an ink containing pigment particles and the like is used for a long period of time.</p>

<p> In order to achieve the above object, the present invention is connected to a recording head for ejecting ink, an ink tank for accommodating ink supplied to the recording head, and a first communication hole provided in the ink tank. To communicate with the atmosphere in the ink tank by being connected to a first flow path for supplying the ink contained in the ink tank to the recording head and a second communication hole provided in the ink tank. The ink in the ink tank is supplied to the recording head by rotating the second flow path, the ink supply unit having the pump arranged in the first flow path, and the pump in the first direction. The ink tank has a tubular member connected to the second communication hole and provided with an opening above the ink liquid level in the ink tank. The ink supply unit includes a first valve arranged on the recording head side of the pump in the first flow path, a second valve arranged in the second flow path, and the first valve. It has a third flow path that connects a portion of the flow path between the pump and the first valve and a portion of the second flow path that is closer to the ink tank than the second valve. The control means is characterized in that, with the first valve and the second valve closed, the pump is rotated in a second direction opposite to the first direction.</p>

<p> According to the present invention, even when an ink containing pigment particles or the like is used for a long period of time, it is possible to prevent the pigment particles or the like from settling and maintain a uniform ink concentration.</p>

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The same reference numerals indicate the same or corresponding parts throughout the drawings. FIG. 9 is a perspective view of an inkjet recording device suitable for using the liquid supply system according to the present invention. In FIG. 9, the inkjet recording apparatus is configured to eject ink from the recording head 524 to the recording medium S based on image information to record an image (including characters, symbols, etc.). The recording head 524 is mounted on the carriage 2. In the recording operation, the recording medium S is conveyed by the transfer roller 3 in the transfer direction A (sub-scanning direction), and the carriage 2 is reciprocated in the direction B (main scanning direction) intersecting the sub-scanning direction. By driving the recording head 524 based on the image information in synchronization with the movement of the carriage, ink is ejected from the recording head to the recording medium. The recording medium S is conveyed by the transfer roller 3 at predetermined pitch intervals, and the entire recording medium is recorded by alternately repeating the transfer at the predetermined pitch and the recording for one line. As the recording medium S, those made of various materials as described above can be used, and usually, a sheet-like medium such as a recording paper or a plastic sheet is used.

On the discharge surface of the recording head 524 facing the recording medium S, a discharge port row composed of a plurality of discharge ports arranged in series in the sub-scanning direction is formed. A plurality of rows of ejection ports are provided according to the number of types of ink used, and in color recording and gradation recording, a desired image is formed by ejecting different inks for each ejection port row. Ink is supplied to the recording head 524 from an ink supply unit 525 to which a plurality of ink tanks 1000 for each color ink are detachably mounted through an ink supply path 626 such as a tube.

FIG. 1 is a schematic configuration diagram showing a case where the liquid supply system according to the first embodiment of the present invention is used in an inkjet recording device as an example. FIG. 2 is a perspective view showing the liquid storage container in FIG. FIG. 3 is an exploded perspective view of the liquid storage container of FIG. FIG. 4 is an exploded perspective view showing the connection unit further exploded in the exploded perspective view of FIG. FIG. 5 is an enlarged vertical sectional view showing a detailed structure of the connection unit of the liquid storage container in FIG.

In FIGS. 1 to 5, the liquid storage container 1000 is used by being mounted with the connection ports 150 and 151 of the connection unit 100 facing downward. Therefore, the connection unit 100 side having the connection ports 150 and 151 is the bottom of the liquid storage container 1000. That is, when the liquid storage container 1000 is the ink tank of the inkjet recording device as shown in FIG. 1, it is attached to the tank mounting portion of the ink supply unit 525 of the inkjet recording device with the connection ports 150 and 151 facing downward. It is attached detachably. Then, it is used to supply ink to the inkjet recording head 524 as a recording means.

Here, each component of the liquid storage container 1000 will be described. As shown in FIG. 3, the liquid storage container 1000 includes a liquid storage unit (ink storage unit) 200, which is a container body for storing liquid (ink), and a connection unit 100 for taking out the liquid in the liquid storage unit 200. ing. Further, it includes an information storage medium unit 300 for extracting various information about the liquid storage container 1000, and a cap 400. The liquid storage unit 200 is a hollow container formed by blow molding a plastic material. In the connection unit 100, a liquid supply hollow needle (ink supply needle) 528 forming the first communication hole and an atmosphere introduction hollow needle (air introduction needle) 529 forming the second communication hole are inserted. It has 1st and 2nd connections. The connection unit 100 is pressed and sandwiched in an airtight state with respect to the opening 201 of the liquid storage portion 200 via the seal member 101. The cap 400 is screwed to the outer peripheral male screw portion of the opening 201 in order to press and hold the connection unit 100 against the opening 201. The information storage medium unit 300 is positioned and fixed to the side surface of the liquid storage unit 200 by ultrasonic welding or the like.

Next, the details of the connection unit 100 will be described with reference to FIGS. 4 and 5. The connection unit 100 has a plurality of connection portions, and has a housing 102 in which openings 153 and 154 corresponding to connection ports 150 and 151 leading to each connection portion are formed. The connection unit 100 is further configured by integrating two elastic members 103, a pressing member 104, two absorbers 105, an absorber cover 106, and a cylinder 107. The two rubber-like elastic members 103 are mounted at positions corresponding to the communication holes 153 and 154 of the housing 102. The pressing member 104 has openings 155, 156 corresponding to connection ports 150, 151. The two absorbers 105 are arranged on the pressing member 104. The absorber cover 106 is mounted on the outside of the two absorbers 105. The tubular member 107 is a tubular body having an open upper and lower ends, and is fixed on the housing 102 at the lower ends.

In this way, the liquid storage container 1000 formed by combining the liquid storage unit 200 and the connection unit 100 is configured. The connection unit 100 is mounted in the opening 201 of the liquid storage unit 200. The connection unit 100 has a first connection for deriving the liquid from the liquid storage and a second connection for introducing gas (air) into the liquid storage. A hollow needle for liquid supply (ink supply needle) 528 that forms a first communication hole for leading out the liquid from the liquid storage portion 200 is inserted into the first connection portion. Further, a hollow needle (air introduction needle) 529 for introducing air, which forms a second communication hole for introducing gas (air) into the liquid storage portion 200, is inserted into the second connection portion. Further, the elastic member 103 is held in a compressed state at these connecting portions. The connection ports 150 and 151 are formed on the absorber cover 106. Further, the pressing member 104 is fixed to the housing 102 by ultrasonic welding or locking claws (not shown).

Each elastic member 103 is a dome-shaped rubber-like member. Each elastic member 103 is attached to each of the two recesses of the housing 102 and is compressed and fixed by the pressing member 104. As a result, the elastic member 103 generates a compressive reaction force in the radial direction and maintains an airtightly sealed state. Further, the two absorbers 105 arranged on the pressing member 104 are sandwiched by the absorber cover 106. The absorber cover 106 is fixed to the pressing member 104 or the housing 102 by ultrasonic welding, locking claws, or the like. The upper surface of the housing 102, which surrounds the communication hole 154 through which the air introduction needle 529 forming the second communication hole is inserted, is the upper part of the liquid storage portion 200 (which is also the inside of the liquid storage container 1000). A tubular member 107 having a length extending to the above is fixed. The upper end of the tubular member 107 is open to the space above the liquid surface in the liquid storage portion 200. Therefore, the inside of the tubular member 107 is a space in which air exists, and the air introduction needle 529 forms a second communication hole with this air space. A small amount of liquid that does not obstruct the air communication of the air introduction needle 529 may stay at the bottom of the tubular member 107. The tubular member 107 is also fixed to the housing 102 by ultrasonic welding, locking claws (not shown), fitting, or the like. As described above, the connection unit 100 is configured.

As shown in FIG. 5, the connection unit 100 is sealed by interposing a sealing member 101 in the opening 201 of the liquid storage portion (container body) 200 and screwing the cap 400 to the outer periphery of the opening 201. It is fixed with. When using the liquid storage container 1000, as shown in FIG. 5, the hollow needle 528 for supplying the liquid is directly connected to the inside of the liquid storage unit 200. On the other hand, the air introduction needle 529 protrudes into the tubular member 107 installed in the container body 200. The liquid supply needle 528 and the air introduction needle 529 penetrate the connection ports 150 and 151, the absorbers 105 and 105, the communication holes 155 and 156, the elastic members 103 and 103, and the communication holes 153 and 154, and inside the container body 200. It protrudes to. The liquid supply needle 528 constitutes a first communication hole for leading out the liquid, and the gas introduction needle 529 constitutes a second communication hole for introducing gas (outside air).

In FIG. 5, the cap 400 has a cylindrical shape with both ends open as a whole. Therefore, the connection ports 150 and 151 formed in the connection unit 100 are exposed even when they are fixed to the liquid storage portion 200 with the cap 400. An engaging portion 401 for sandwiching the connection unit 100 between the opening 201 and the cap 400 is formed in the inner diameter portion of the cap 400 screwed to the opening 201. The sealing member 101 is compressed by a predetermined amount between the annular stepped portion 157 formed on the outer periphery of the housing 102 and the end face of the opening 201 of the liquid accommodating portion 200 by screwing the cap 400. As a result, the inside of the ink tank 1000 is kept airtight from the outside air.

Next, the information storage medium unit 300 will be described. In FIG. 4, the information storage medium unit 300 includes a holder 301 and a storage medium 302 positioned and fixed to the inner surface of a recess of the holder 301 by a double-sided tape 303. The information storage medium unit 300 is provided with a comb-shaped ID unit (mechanical identification unit) composed of a plurality of protrusions 304. The storage medium 302 can exchange information with the recording device in a state where the liquid storage container 1000 is attached to the inkjet recording device as an ink tank. The information communicated with the recording device is, for example, information regarding the expiration date of the ink, the amount of ink in the ink tank 1000, the color of the ink, and the like. By extracting such information from the control unit of the recording device, it is possible to issue an alarm of expiration date or out of ink to urge the user to replace the ink tank. As a result, it is possible to prevent adverse effects on the recorded image due to discoloration and thickening of the ink. In addition, it is possible to prevent inconveniences such as recording when the ink is out or recording when an ink tank containing ink of a different color is erroneously installed.

As the storage medium 302, various media such as a flash memory and a write-at-once magnetic medium can be used as long as the identification information can be obtained by information acquisition means such as magnetism, magneto-optical, electric, and mechanical. Can be done. In the ink tank 1000 of the present embodiment, an EEPROM capable of electrical write / erase processing is used. This is a storage medium capable of holding ink tank identification information, writing information from the recording device main body side, adding storage information from the recording device main body side, or changing or deleting the storage information. This EEPROM is mounted on a printed circuit board having a contact portion that is electrically connected to an electric signal connector provided on the recording device main body side. The comb-shaped protrusion 304 is used as an ID for preventing erroneous mounting of the ink tank. A predetermined portion such as each ink color or each model of the recording device is excised, and a protrusion is provided at a position on the main body side corresponding to the excised portion. As a result, only the correct ink tank is mounted, and in addition to preventing erroneous mounting by the storage medium 302, erroneous mounting is also prevented by the mechanical configuration.

Next, with reference to FIG. 1, a case where the liquid supply system according to the present embodiment is used in an inkjet recording device will be described as an example. In FIG. 1, the liquid storage container 1000 is connected to the inkjet recording head 524 as a recording means via the connection unit 100. The recording head 524 discharges ink from the ejection port to the recording medium based on the image information to record an image. The recording head 524 of the present embodiment is an inkjet recording head that ejects ink by using thermal energy, and includes an electrothermal converter for generating thermal energy. Further, the recording head 524 causes a film to boil in the ink by the heat energy applied by the electrothermal converter, and discharges the ink from the ejection port by utilizing the pressure change due to the growth and contraction of the bubbles generated at that time. It is for recording.

In FIG. 1, the recording head 524 is connected to the ink tank 1000 via an ink supply path 526 and an ink supply unit (tank mounting portion) 525. The ink (liquid) supply unit 525 is provided with a hollow ink supply needle (ink lead-out needle) 528 and an air introduction needle 529. The ink supply needle 528 for deriving the ink penetrates the elastic member 103 of one connection port 150 of the ink tank 1000 and extends into the liquid storage portion 200. A needle hole is formed near the tip of the ink supply needle 528. In this way, a first communication hole made of a hollow needle for drawing out the ink is formed. At this time, since the elastic member 103 is loaded in a compressed state, the airtightness of the outer peripheral surface of the ink supply needle 528 is maintained, and ink leakage is prevented. The ink supply unit 525 is provided with a flow path 531 connecting the ink supply needle 528 and the ink supply path 526. A pump 304 and an on-off valve 302 are provided in the middle of the flow path 531. The pump 304 can pump the liquid and air in the flow path, and the pumping direction can be switched to either the arrow A or the arrow B direction.

Further, the air introduction needle 529 for introducing outside air when the ink is supplied to the recording head penetrates the elastic member 103 of the other connection port 151 of the ink tank 1000 and extends into the liquid storage portion 200. A needle hole is formed near the tip of the air introduction needle 529. In this way, when the ink is supplied to the recording head, a second communication hole made of a hollow needle for introducing air from the outside is configured. Also at this time, since the elastic member 103 is loaded in the compressed state, the airtightness of the outer peripheral surface of the air introduction needle 529 is maintained, and ink leakage is prevented. One end of the air introduction needle 529 communicates with the internal space (air) of the tubular member 107, and the other end communicates with the outside air via a flow path 532 formed in the ink supply unit 525. An on-off valve 303 is provided in the flow path 532. In the present embodiment, a third flow path 533 connecting the above-mentioned flow path 531 and the above-mentioned flow path 532 is provided, and an on-off valve 301 is arranged in this flow path 533.

Next, a case where the ink supply operation of the inkjet recording apparatus is performed using the liquid supply system according to the first embodiment will be described with reference to FIGS. 1 to 5. This ink supply operation is performed by the liquid supply mode. The liquid storage container 1000 in this case corresponds to the ink tank of the inkjet recording device. In FIG. 1, the liquid (ink) supply unit 525 is provided with flow paths 531, 532, and 533. The first flow path 531 is arranged so that the ink supply needle (first communication hole) 528 and the recording head 524 can be connected to each other. A pump 304 and an on-off valve 302 are provided in the middle of the first flow path 531 in the arrangement as shown in the drawing. The pump 304 constitutes a liquid or gas supply driving means.

The second flow path 532 is arranged so that the air introduction needle (second communication hole) 529 and the outside air can be connected to each other. An on-off valve 303 is provided in the middle of the second flow path 532 in an arrangement as shown in the drawing. The third flow path 533 is a flow path connecting the ink supply needle 528 and the air introduction needle 529. The third flow path 533 includes a portion between the ink supply needle 528 and the pump 304. It also includes a portion of the first flow path 531 between the pump 304 and the valve 302. Further, the third flow path 533 includes a portion between the pump 304 and the valve 303, and includes a portion between the air introduction needle 529 and the pump 304. An on-off valve 301 is provided in the middle of the third flow path 533. By installing the ink tank, the above three flow paths are connected via the ink tank.

The recording head 524 discharges ink from a discharge port formed on the discharge surface (front surface) and records an image on a recording medium such as paper or a plastic sheet. The pump 304 supplies the ink in the ink tank 1000 to the recording head 524 through the ink supply path 526 so as to replenish the ink consumed by the ejection. At this time, the valves 302 and 303 are in the open state, and the valves 301 are in the closed state. When the amount of ink in the liquid storage unit 200 decreases with the supply of ink, the pressure in the liquid storage unit decreases. Then, the air introduced from the flow path 532 that communicates with the outside air is introduced into the space on the liquid surface in the liquid accommodating portion 200 through the air introduction needle 529 and the tubular member 107. The above liquid (ink) supply operation can be executed by the liquid supply mode in the present embodiment.

6 to 8 show the gas circulation mode (gas circulation in the tank) in which gas (air) is circulated in the liquid storage part, unlike the liquid circulation mode for supplying ink to the recording head in the liquid supply system of FIG. It is a schematic diagram which shows the state at the time of performing. This gas circulation mode allows the liquid in the liquid container to be agitated. That is, FIG. 6 is a schematic view showing a state when the air pushed into the liquid storage portion from the first communication hole in the liquid supply system of FIG. 1 is mixed with the ink of the high concentration layer. FIG. 7 is a schematic view showing a state when the air pushed into the liquid storage portion in the liquid supply system of FIG. 6 is further mixed with the inks of the medium concentration layer and the low concentration layer. FIG. 8 is a schematic view showing a state in which the air and the liquid in the liquid storage portion are totally agitated in the liquid supply system of FIG.

Next, a case where a pigment ink containing pigment particles as a colorant is contained in the liquid storage unit 200 will be described. In FIGS. 1 and 6 to 8, when the ink tank, which is a liquid storage container, is left for a long time with the 1000 attached (used state) in the liquid supply system of the inkjet recording device, the inside of the ink tank 1000 Pigment particles settle. Then, the concentration of the pigment particles is inclined from the bottom to the top inside the liquid storage portion 200. As a matter of course, the concentration gradient in this case is higher at the bottom than at the top.

The concentration distribution of the pigment particles is roughly as shown in FIGS. 1 and 6. That is, a high-concentration layer 603 having a high concentration of pigment particles is formed at the bottom, and a low-concentration layer 601 having a low concentration of pigment particles is formed at the top. Then, in between these, a medium-concentration layer 602 that maintains almost the initial pigment particle concentration is formed. In other words, it is roughly divided into three layers. Here, the on-off valve 301 is opened and the on-off valves 302 and 303 are closed. In this state, the ink tank 1000 becomes a closed system via the pump 304. Then, the pump 304, which is a supply driving means, is operated in the direction of arrow B inside this closed system. In this case, the upper end opening 107a of the tubular member 107 is located higher than the liquid level of the upper low-concentration layer 601. In this state, the pump 304 is operated in the direction of arrow B.

As a result, the air in the liquid accommodating portion 200 is led out to the outside of the tank via the tubular member 107 and the air introduction needle 529. At the same time, the derived air is pushed (pushed) into the liquid storage unit 200 via the ink supply needle 528 forming the first communication hole in the flow path. By the operation of the pump 304, the air in the upper space in the liquid storage portion 200 is again led out to the outside of the tank through the tubular member 107 and the air introduction needle 529 forming the second communication hole. Then, again, the air led out to the outside of the tank by the operation of the pump 304 is introduced into the liquid storage unit 200 via the ink supply needle 528. That is, the air in the liquid accommodating portion 200 is circulated through the tubular member, the air introduction needle, the pump, and the ink supply needle.

In the illustrated configuration, the air above the ink tank 1000 is circulated by the pump 304 through the closed flow path of the ink supply unit (tank mounting part) 525, and the circulated air agitates the ink in the ink tank. It is configured. That is, a gas circulation mode is implemented in which the gas existing inside the liquid storage unit 200 is circulated through a closed system formed in the ink supply unit 525 to mix this gas with the liquid in the liquid storage unit 200. can do. Then, depending on the behavior of the gas and the liquid at the time of mixing, the liquid (for example, an ink containing pigment particles) can be agitated. Stirring by this circulation is performed without wasting (without discarding) the liquid (ink) in the liquid storage container (ink tank) 1000.

On the other hand, the posture of the ink tank 1000 changes in all directions in the process of distribution until it is manufactured and attached to the main body of the recording device. Ink may flow into the tubular member 107 due to this change in posture. Therefore, immediately after the user attaches the ink tank 1000 to the recording device main body, ink may be present inside the tubular member 107. However, by forming a closed flow path system from the air introduction needle 529 to the ink supply needle 528 as described above and operating the pump 304 in the direction of arrow B, the ink existing in the tubular member 107 can be removed. It circulates and is introduced into the ink tank 1000 again. That is, since the ink drawn out from the tubular member 107 is circulated and introduced into the ink tank again, the ink is not wasted in this case as well. Then, the ink once drawn out from the tubular member 107 does not flow into the tubular member 107 again.

Next, the stirring action by circulating the air in the ink tank 1000 and reintroducing it from the bottom of the ink tank will be described. In FIG. 6, the air 610 introduced from the bottom of the ink tank 1000 through the first communication hole of the ink supply needle 528 moves toward the upper part in the container. This movement of air pushes up the high-concentration layer 603 of the pigment ink, and a part of the high-concentration layer 603 is mixed into the medium-concentration layer 602. Here, the two liquid layers composed of the high-concentration layer 603 and the medium-concentration layer 602 and one gas 610 composed of air have different properties. First, the high-concentration layer 603 of the pigment particles is pushed upward by the air 610, and the specific gravity of this high-concentration layer is larger (heavier) than the specific gravity of the surrounding medium-concentration layer 602. Further, although the medium concentration layer 602 is stationary, the specific gravity of the medium concentration layer is smaller than the specific gravity of the mixed high concentration layer 603. And the air 610 is moving upward, but the specific gravity of this air is smaller than the two liquid layers 602 and 603.

Due to such a difference in properties, the high-concentration layer 603 is once pushed up by the air 610, but the ink in the portion of the high-concentration layer that is out of the air 610 sinks because the specific gravity is larger than that of the medium-concentration layer 602. .. Also, since the air 610 is lighter than the other two liquid layers, the movement of the air depends on the conditions of the surrounding liquid. That is, the air 610 does not move upward in a straight line, but moves upward with an amplitude. Further, the rise of the air 610 is continuously generated by the above-mentioned air circulation, and a complicated air flow is generated. Therefore, the high-concentration layer 603, the air 610, and the medium-concentration layer 602 are mixed with each other, and the pigment particles in the ink are further diffused and mixed.

Then, as shown in FIG. 7, the ink in which the medium-concentration layer 602 and the high-concentration layer 603 of the pigment ink are mixed is pushed up into the low-concentration layer 601 by the air 610 as in FIG. This stirs the pigment particles in the ink. The stirring mechanism in this case is the same as in the case of the high-concentration layer 603, the air 610, and the medium-concentration layer 602 described above. That is, as shown in FIG. 8, by operating the pump 304, the air 610 is mixed with the ink while rising inside the ink tank 1000. At the same time, the air above the liquid level inside the ink tank is led out to the outside of the tank through the tubular member 107 and the air introduction needle 529. The derived air is again introduced into the ink tank 1000 by the pump 304 via the ink supply needle 528 and mixed with the ink while ascending in the ink tank. In this way, the air 610 repeats circulation and agitation through the tubular member 107. Then, as the air 610 continuously rises from the bottom to the top of the ink tank 1000, an ink flow as shown by an arrow in FIG. 8 is generated inside the ink tank, and the ink inside the ink tank is discharged. It is agitated.

According to the embodiment described above, the ink in the liquid storage container 1000 can be agitated by using the air inside the liquid storage container 1000 and circulating the air inside the container again via the outside of the container. As a result, even when the pigment ink in the liquid storage container 1000 is used for a long period of time, it is possible to prevent a density difference from occurring in the image recorded on the recording medium. That is, even if the device is left unused for a long period of time, the ink tank 1000 can continue to supply ink having a concentration suitable for the recording head 524. Therefore, in a liquid supply system having a liquid storage container 1000 for storing ink using a pigment as a colorant, liquid storage capable of recording a high-quality image with no difference in density without causing wasteful consumption of ink. A container is provided.

FIG. 10 is an enlarged vertical sectional view showing a detailed structure of a connection unit of a liquid storage container of the liquid supply system according to the second embodiment of the present invention. FIG. 11 is a schematic view showing the state of the meniscus of air and ink in the filter in FIG. FIG. 12 is a schematic view showing a state in which air moves up in the ink by breaking the meniscus of Philou in FIG. FIG. 13 is a schematic view showing a state when the gas pushed from the first communication hole of the liquid storage container is mixed with the ink of the high concentration layer in the liquid supply system according to the second embodiment of the present invention. .. FIG. 14 is a schematic view showing a state in which foreign matter in the ink is deposited on the filter in FIG. FIG. 15 is a schematic diagram showing a state in which foreign matter on the filter is removed by the air rising through the meniscus of the filter in FIG. Next, the liquid storage container of the liquid supply system according to the second embodiment of the present invention will be specifically described with reference to FIGS. 10 to 15.

The configuration of the entire liquid supply system when the liquid storage container 1000 is used as the ink tank of the inkjet recording device is substantially the same as the configuration of the first embodiment shown in FIG. 1, and detailed description thereof will be omitted. To do. In FIG. 10, in the present embodiment, the communication hole of the housing 102 is inside the liquid storage unit 200.<u style="single">153</u>A filter 305 is provided above the. This filter 305 is for removing foreign matter existing in the liquid storage unit 200 when the pump 304 in FIG. 1 operates in the direction of arrow A in the figure to supply ink to the recording head 524. is there. Therefore, the filter 305 is configured to circulate only the ink while blocking foreign matter in the ink.

In recent years, recorded images in inkjet recording devices have become extremely high-definition, each ink droplet (dot) constituting the image has become extremely small, and the ejection port for ejecting such ink droplets has also become extremely small. It has become. Therefore, if foreign matter is mixed in the ink supplied to the recording head 524, the ejection port is likely to be clogged and ejection failure is likely to occur. In view of such technical problems, in the present embodiment, the filter 305 shown in FIG. 10 is provided in order to record a stable high-quality image by removing foreign substances in the ink.

The liquid storage container 1000 of the liquid supply system according to the present embodiment is different from the first embodiment described above in that the filter 305 is additionally mounted, and is substantially the same in other respects. Therefore, the ink supply operation when the liquid storage container 1000 is used as the ink tank of the inkjet recording device is substantially the same as that of the first embodiment described above. Hereinafter, in the present embodiment, the stirring action by circulating the air in the ink tank 1000 and reintroducing the air from the bottom of the ink tank 1000 will be described. In this embodiment, as shown in FIG. 11, the ink and air 610 form a meniscus in the capillaries of the filter 305, and the air 610 moves upward through the capillaries. Then, as shown in FIG. 12, the air 610 eventually breaks the meniscus, mixes into the ink, and rises.

The movement of the air 610 and the timing of breaking the meniscus depend on the surface condition of the ink and the filter 305. Therefore, the interval at which the air 610 is mixed into the ink becomes random, and the flow between the air 610 and the ink becomes complicated. This complex flow promotes mixing of air and ink and enhances the stirring effect of pigment particles in the ink. As shown in FIG. 12, each air 610 is fine and light, and is easily affected by the flow around the air 610, so that the movement of the air 610 in the ink becomes intense. Therefore, the air 610 rises while drawing a more complicated orbit. At this time, the ink entering between the air 610 complicates the flow of the air and the ink, which further promotes the mixing of the air and the ink and further enhances the stirring effect.

Further, as described above, each air 610 is fine, but since ink enters between them, a mixture of rising air 610 and ink is generated as shown in FIG. 13, and this is almost integrated. And rise. Therefore, even with the same volume of air 610, more ink can be pushed up. Further, with the stirring operation, air 610 is discharged upward from the upper surface of the filter 305. Therefore, even if the foreign matter 611 is present on the filter 305 as shown in FIG. 14, the foreign matter 611 can be removed from the filter 305 as the air 610 rises as shown in FIG. In this case, since the foreign matter 611 is only returned to the ink, the foreign matter 611 is deposited on the filter 305 again, albeit little by little, when the normal ink supply is performed. However, by performing the stirring operation at a predetermined timing, a smooth ink supply operation can be maintained.

According to the embodiment described above, the liquid in the liquid container can be agitated only by circulating the gas, and even when the liquid containing the pigment particles or the like is stored for a long period of time, the pigment particles or the like can be prevented from settling. Provides a liquid storage container capable of keeping the concentration of the liquid uniform. Therefore, when the liquid storage container is used as the ink tank of the inkjet recording device, the liquid storage container and the inkjet recording device that enable good image recording at a desired concentration are provided.

In the above embodiment, the case where the inkjet recording device using the liquid storage container as the ink tank is a serial type using a recording head that moves along the recording medium has been described as an example. The present invention is similarly applicable to a line-type inkjet recording apparatus that records only by sub-scanning. Further, the present invention can be similarly applied to an inkjet recording apparatus regardless of the number of recording heads, the number of types and properties of ink used, and the like. Further, the present invention is not limited to a single device such as a printer, a copying machine, a facsimile, and an image capturing image forming device, and is widely applied as a compound device combining these or a recording device in a complex device such as a computer system. It is possible.

<figref num="1">It is a schematic block diagram of the liquid supply system which concerns on 1st Embodiment of this invention.</figref><figref num="2">It is a perspective view which shows the 1st Embodiment of the liquid storage container in FIG.</figref><figref num="3">It is an exploded perspective view of the liquid storage container of FIG.</figref><figref num="4">It is an exploded perspective view which shows the connection unit further exploded in the exploded perspective view of FIG.</figref><figref num="5">It is an enlarged vertical sectional view which shows the detailed structure of the connection unit of the liquid storage container in FIG.</figref><figref num="6">It is a schematic diagram which shows the state when the air pushed into the liquid storage part from the 1st communication hole is mixed with the ink of a high density layer in the liquid supply system of FIG.</figref><figref num="7">It is a schematic diagram which shows the state when the air pushed into the liquid storage part is further mixed with the ink of a medium-concentration layer and a low-concentration layer in the liquid supply system of FIG.</figref><figref num="8">It is a schematic diagram which shows the state which the air and the liquid in a liquid storage part are agitated as a whole in the liquid supply system of FIG.</figref><figref num="9">It is a perspective view of the inkjet recording apparatus suitable for using the liquid supply system of this invention.</figref><figref num="10">It is an enlarged vertical sectional view which shows the detailed structure of the connection unit of the liquid storage container of the liquid supply system which concerns on 2nd Embodiment of this invention.</figref><figref num="11">It is a schematic diagram which shows the state of the meniscus of air and ink in the filter in FIG.</figref><figref num="12">It is a schematic diagram which shows the state which breaks the meniscus of the filter of FIG. 11 and the air moves up in ink.</figref><figref num="13">It is a schematic diagram which shows the state when the gas pushed from the 1st communication hole is mixed with the ink of a high density layer when the liquid supply system which concerns on 2nd Embodiment of this invention is used in an inkjet recording apparatus. is there.</figref><figref num="14">It is a schematic diagram which shows the state which the foreign matter in ink is deposited on the filter in FIG.</figref><figref num="15">It is a schematic diagram which shows the state which the foreign matter on a filter is removed by the air which breaks through the meniscus of a filter in FIG. 14 and rises.</figref>

Code description

100 connection unit 107 Cylindrical member 107a Top opening 200 Liquid compartment 201 opening 301, 302, 303 Open / close valve 304 pump 305 filter 524 Recording Head (Inkjet Recording Head) 525 Liquid supply unit (ink supply unit, tank mounting part) 526 Ink supply path 528 First communication hole (liquid supply needle, ink supply needle) 529 Second communication hole (gas introduction needle, air introduction needle) 531 First flow path 532 Second flow path 533 Third flow path 601 Low density layer of pigment ink 602 Medium density layer of pigment ink 603 High density layer of pigment ink 610 Gas (air) 611 Foreign matter 1000 Liquid storage container (ink tank)