JP2007223159A - Ink storing container and ink supplying system using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink tank which eliminates concentration unevenness of a supply ink without wasteful consumption of the ink, and carries out ink supply such that a density difference of a level visually recognizable in a recorded object is avoided even in the ink tank wherein the ink using a pigment as a coloring agent is carried. <P>SOLUTION: The ink storing container which supplies to an ink-jet recorder has an ink storing chamber which stores the ink, an ink supplying port provided at a bottom part of the ink storing chamber inner wall for supplying the ink in the ink storing chamber to the outside, an atmosphere inlet provided at a bottom part of the ink storing chamber for introducing the atmosphere into the ink storing chamber, and at least one tilting face continuous with the bottom part of the ink storing chamber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink storage container that is detachably mounted on an ink jet recording apparatus, and an ink supply system using the ink storage container.

  The ink jet recording apparatus performs recording by ejecting ink to a recording medium from a plurality of ejection openings provided in an ink jet recording head. In this ink jet recording apparatus, an ink tank that supplies ink to the ink jet recording head is called an on-carriage type ink tank that is mounted on the carriage integrally with the ink jet recording head, and an ink jet recording head that is not mounted on the carriage. In contrast, an ink tank of an off-carriage type that supplies ink via a supply member can be used. Many off-carriage type ink tanks are detachably connected to the end of an ink supply system that supplies ink used for recording to a recording head. In a conventional removable ink tank, a capillary force generating member such as a sponge is provided inside the ink tank, and the ink is held directly in the flexible bag or the rigid casing. What is held is known. In particular, a wide format printer with a large ink supply amount per sheet and a network printer with a high operation rate require a large amount of ink. For this reason, in consideration of reduction of ink tank replacement frequency and ink storage efficiency, an ink tank of a type that directly stores ink without providing a sponge or the like in the tank (hereinafter referred to as “whole-type ink tank”). Also called).

  In such an all life type ink tank, a dye ink that can always maintain a uniform ink density has been used. However, the recorded matter recorded using the dye ink has poor light resistance, gas resistance, and water resistance, and is not suitable for outdoor postings and recorded matter for long-term storage. On the other hand, a pigment ink containing a pigment as a colorant is superior in light resistance, gas resistance, water resistance, and the like as compared with a dye ink. However, since the pigment is not dissolved in the solvent but dispersed in the solvent, the pigment settles in the stationary ink tank.

  In the above-described on-carriage type ink tank, the ink tank vibrates by scanning of the carriage, and the ink is supplied as needed while the ink inside is agitated. Sent to. On the other hand, in an off-carriage type ink tank, ink is supplied in a state of being fixed at a predetermined position, so that the pigment sedimentation phenomenon cannot be ignored.

  For example, the pigment settles inside the ink tank left for a long time, the concentration gradient of the pigment particles occurs from the bottom of the tank toward the liquid surface, and the bottom is an excessively dark layer, while the liquid surface The vicinity is an excessively light colored layer, and the ink density is greatly changed near the bottom and the liquid surface. If the ink tank is configured to derive ink from the bottom of the ink tank, excessively dark ink will be derived first. When a large amount of recording is performed in this state and the recording results immediately after the start of recording are compared with the recording results immediately before the end, there may be a color difference that can be visually observed. This phenomenon is particularly noticeable in color printing in which an image is formed by color shading.

  In order to solve this problem, there is a method of generating convection in the ink in the ink tank by generating bubbles from a tube member located at a position protruding from the bottom surface of the ink tank.

  As the configuration, as in Patent Documents 1, 2, and 3, an ink supply pipe that supplies ink to the ink jet recording head and an air communication pipe that communicates with the atmosphere are provided at positions protruding from the bottom surface of the ink tank.

  When ink is supplied from the ink tank to the recording head through the ink supply port, the corresponding volume of air enters the ink tank from the atmosphere communication pipe. The bubbles generate convection in the ink in the ink tank and stir the ink, thereby eliminating pigment sedimentation and preventing uneven density.

Also, by setting the pipe for supplying ink to the ink jet recording apparatus higher than the bottom surface of the ink tank, the ink that has settled on the bottom surface of the ink tank and has a high concentration is prevented from being taken into the ink supply pipe.
JP 2002-307710 A Japanese Patent No. 2929804 Japanese Patent Laid-Open No. 9-85962

  However, the conventional ink tank has the following problems.

  Naturally, the pigment settles at the bottom of the tank, but the bubbles do not directly stir the sedimented layer accumulated at the bottom, but are indirectly stirred by the convection in the ink tank generated by the bubbles. Therefore, sufficient convection is not generated in the vertically downward direction from the pipe for introducing bubbles. Therefore, if the sedimentation degree is heavy, it takes time for stirring or sufficient stirring cannot be performed.

  In particular, since bubbles can be generated and convection can be generated only by the amount of ink supplied from the ink supply pipe, there are cases where sufficient convection cannot be generated.

  Further, the ink supply pipe in the ink tank protrudes vertically upward from the bottom surface of the ink tank so that the high pigment concentration ink layer settled on the bottom of the tank is not supplied to the ink jet recording head. This increases the remaining amount of ink in the ink tank, leading to an increase in printing cost.

  In order to solve the above problems, pigment settling can be prevented and improved by forcibly consuming the ink corresponding to the amount of bubbles necessary for stirring even if printing / recovery is not necessary, but it is discarded. Ink is wasted and this is not as effective as it is.

  The present invention has been made in view of such a conventional problem. Even in an ink tank equipped with an ink using a pigment as a colorant, the concentration unevenness of the supplied ink can be achieved without wasteful ink consumption. It is an object of the present invention to provide an ink tank that supplies ink so as not to cause a density difference that can be visually observed on a recorded matter.

  In order to solve the above problems, an ink storage container according to the present invention is an ink storage container supplied to an ink jet recording apparatus, wherein the ink storage chamber for storing the ink and the ink provided at the bottom of the wall of the ink storage chamber An ink supply port for supplying the ink in the storage chamber to the outside, an air introduction port provided at the bottom of the ink storage chamber for introducing the air into the ink storage chamber, and a bottom of the ink storage chamber And at least one slope.

  According to the said structure, the settled pigment component is concentrated on the vertical direction bottom face in an ink tank, and more effective stirring is attained. Furthermore, the ink can be stirred without wasting ink.

  Accordingly, density unevenness in the ink tank is eliminated, and a liquid with a constant density can be supplied from the ink supply port, and high-quality print quality without density difference can be obtained.

(First embodiment)
The ink tank according to the first embodiment of the present invention will be described below with reference to the drawings.

  A recording apparatus provided with an ink supply system suitable for the ink tank of the present invention will be described. FIG. 2 shows an ink jet recording apparatus as an example of an apparatus to which the ink tank of the present invention is applied. The ink jet recording apparatus shown in FIG. 2 has a reciprocating movement (main scanning) of an ink jet recording head (corresponding to the ink jet head 42 in FIG. 17 and the like) 1 and a predetermined recording sheet S such as general recording paper, special paper, or OHP film. By repeating the conveyance (sub-scanning) for each pitch and synchronizing with these movements, ink is selectively ejected from the inkjet recording head 1 and adhered to the recording sheet S, thereby allowing characters, symbols, images, etc. This is a serial type recording device to be formed.

  In FIG. 2, the ink jet recording head 1 is detachably attached to a carriage 2 that is slidably supported by two guide rails 8 and 9 and reciprocated along the guide rails 8 and 9 by a driving means such as a motor (not shown). It is mounted as possible. The recording sheet S is opposed to the ink ejection surface of the inkjet recording head 1 by the conveyance roller 3 and crosses the moving direction of the carriage 2 so as to maintain a constant distance from the ink ejection surface (for example, , In the direction of arrow E, which is an orthogonal direction.

  The ink jet recording head 1 has a plurality of nozzle rows for ejecting inks of different colors. A plurality of independent ink tanks are detachably attached to the ink supply unit 5 in accordance with the color of ink ejected from the ink jet recording head 1. The ink tank 11 can be stored in the ink supply unit 5 by storing the ink tank 11 in the ink supply unit 5 and closing the ink supply unit lid 10 from above.

  The inkjet recording head 1 has a plurality of nozzles, generates bubbles in the ink using thermal energy generated by the electrothermal transducer corresponding to each nozzle, and ink droplets are generated from the nozzles by the generated pressure of the bubbles. Discharge.

  The ink supply unit 5 and the inkjet recording head 1 are connected to each other by a plurality of ink supply tubes 6 corresponding to the colors of the inks, and the inks of the respective colors stored in the ink tank 11 are supplied to the nozzle rows of the inkjet recording head 1. Can be supplied independently.

  The recovery unit 7 is disposed so as to face the ink ejection surface of the ink jet recording head 1 in a recording region that is within the reciprocating movement range of the ink jet recording head 1 and outside the passing range of the recording sheet S. Has been. The recovery unit 7 includes a cap portion for capping the ink discharge surface of the ink jet recording head 1, a suction mechanism for forcibly sucking ink from the ink jet recording head 1 with the ink discharge port surface being capped, and an ink discharge surface. A cleaning blade for wiping off the dirt.

  FIG. 3 is a perspective view of the ink tank 11 as viewed from the bottom.

  In FIG. 3, reference numeral 21 denotes a bottom cover, which connects the ink supply path on the ink jet recording apparatus side and the ink tank 11 when mounted on the ink jet recording apparatus. The bottom cover 21 is mounted with the first connection port 27 and the second connection port 28 facing downward in the vertical direction. That is, the bottom cover 21 is the bottom of the ink tank 11.

  FIG. 4 is a diagram illustrating a state in which the ink tank illustrated in FIG. 3 is disassembled.

  As shown in FIG. 4, the ink tank includes an ink storage portion 14, a lid 15 a, an elastic member 16, a storage medium holder 17, a storage medium 18, a double-sided tape 19, a fixing member 20, a bottom cover 21, and a lid pressing member 22. The The ink storage portion 14 has an open top surface 14a and stores ink directly inside. The lid 15 a closes the opening of the top surface 14 a of the ink storage unit 14.

  The elastic body 16 is inserted into the two openings provided in the opening guide portion 14 c on the bottom portion 14 b outside the ink storage portion 14, and is fixed by the fixing member 20. An ink lead-out connecting needle and an air introducing connecting needle (not shown) and the inner space of the ink containing portion 14 are communicated with each other via an elastic member 16.

  A storage medium holder storage portion 14 d is provided below the ink storage portion 14. In the storage medium holder storage portion 14d, a storage medium holder 17 that holds and holds the electric wiring board 26 having the storage medium 18 that electrically stores the identification information (ID) of the liquid storage container with the double-sided tape 19 is provided through a gap. Stored.

  Further, a bottom cover 21 is attached to the bottom part 14b, whereby an opening guide part 14c into which the elastic member 16 is inserted and a storage medium holder storage part in which the storage medium holder 17 to which the storage medium 18 is fixed are stored via a gap. 14d is covered.

  FIG. 5 is a schematic cross-sectional view of the ink tank 11 in FIG. 3 with the ink 12 introduced therein, and is a cross-sectional view in the FF direction.

  In a state where the first connection port 27 into which an unillustrated connection needle for drawing out ink is inserted and the second connection port 28 into which an unillustrated connection needle for introducing air is inserted are attached to the ink jet recording apparatus, Always down in the vertical direction.

  In addition, a slope 30 is continuous between the vertically lowermost surface (bottom surface 29) and the side wall on the inner wall of the ink storage portion 14.

  FIG. 10 is an ink tank in a state in which the ink 12 is introduced into the ink tank 11 in FIG.

  Here again, the inclined surface 30 is continuous between the vertically lowermost surface (bottom surface 29) and the side wall of the inner wall of the ink storage portion 14.

  FIG. 6 is a schematic cross-sectional view showing the ink tank 11 in which the ink jet recording head attached to the ink supply unit 5 provided in the ink jet recording apparatus is in a static state.

  The ink supply unit 5 is provided with a hollow ink lead needle 39 for leading ink in the ink tank and a hollow air introduction needle 38 for introducing air into the ink tank. These needles are respectively inserted into the first connection port 27 (illustrated in FIG. 5) and the second connection port 28 (illustrated in FIG. 5) of the ink tank, so that the ink supply unit 5 is connected to the inside of the ink tank. Communicate. Further, the end 38 a of the air introduction needle is located on the bottom surface of the ink storage unit 14.

  Here, the ink supplied to the recording head 1 needs to be held in a predetermined negative pressure state on the ink jet recording apparatus side. In the case of the present embodiment, the end surface 38a of the air introduction needle 38 that introduces air into the ink tank is disposed at a position vertically lower than the ink discharge port surface 31 of the inkjet recording head 1, and the lower end 38a and the ink discharge port The height difference (water head difference H) from the outlet surface 31 always acts on the inkjet recording head 1 as a negative pressure. That is, a substantially constant negative pressure always acts on the inkjet recording head 1 regardless of the height of the ink level in the ink tank 11.

  FIG. 7 is a schematic cross-sectional view showing the ink state of the ink tank 11 when the ink tank is left in a state where it is not used when attached to the ink supply unit 5 provided in the ink jet recording apparatus.

  The ink mounted on the ink tank of this embodiment is a pigment ink, but there are several types of pigment ink. In other words, self-dispersion type with pigments with hydrophilic groups to have affinity with ink solvent, dispersion-stabilized hydrophobic pigments with surfactants, resin dispersion with low molecular weight resin, microcapsule type, etc. is there. In any case, the pigment is not a dissolution system but a dispersion system. Therefore, when the ink tank is held in the same posture for a long period of time, a phenomenon that the dispersed pigment settles occurs. The ink has a high density at the bottom of the tank.

  Referring to FIG. 7, the ink in the ink tank 11 is an ink having a high pigment concentration on the lower side with respect to the vertical direction, such as the low density layer ink layer 12a and the high density ink layer 12b from the top side. If the ink in the ink tank is derived from the bottom of the tank in this state, the ink is derived from the pigment rich region, and the ink having an increased pigment concentration is supplied. In addition, in the process until the ink in the ink tank 11 is used up, one day, an ink having a greatly reduced density is derived from the initially prepared pigment prescription ratio.

  FIG. 1 is a diagram for explaining a method of stirring ink in which a pigment component in an ink tank has settled in the present invention.

  In FIG. 1, the ink led out from the ink lead-out needle 39 through the ink lead-out tube 41 to the ink jet recording apparatus is sent to the ink jet recording head 1 and discharged. Then, when the ink in the ink storage unit 14 decreases with such movement of the ink, the pressure in the ink storage unit 14 decreases. Then, the bubbles 70 a are introduced from the air introduction tube 44 through the air introduction needle 38 into the ink storage unit 14.

  The air introduction ends when the meniscus force at the portion where the ink and air at the end of the air introduction needle 38 are in contact with the pressure in the ink tank 11 is balanced. The introduced air becomes bubbles 70a and rises in the ink tank.

  By the way, since the weight of a predetermined amount of ink becomes heavier as the pigment concentration is higher, the low concentration layer ink that is lighter than the high concentration layer ink that is heavier than the heavy ink is placed downward in the vertical direction in a situation where stirring is not performed. There is nothing. Here, the generated high-density layer ink in the bottom surface in the ink storage unit 14 is pushed up onto the low-density layer by the generated bubbles 70a. After being pushed up, the high-density layer ink itself tends to sink due to the weight of the high-density layer ink itself, so that the ink is stirred as shown by arrow E, and the ink is uniformly distributed. Therefore, it is possible to make the ink density uniform throughout the ink tank.

  Furthermore, the stagnation in the ink storage portion is reduced by the inclined surface 30, and more effective stirring is possible. In addition, the slope 30 is more effective when the amount of the ink 12 is reduced than in the configuration without the slope.

  FIG. 9 is a diagram showing an ink stirring state in an ink supply system using a conventional ink tank. Here, since the tip of the air introduction needle 38 is not located at the bottom of the ink tank, the pigment component that has settled below the tip of the air introduction needle 38 cannot be directly stirred. Also, since there is no slope inside the ink tank, there is stagnation in the corners in the ink tank, and convection in the ink tank due to the generated bubbles does not reach the stagnation, and there is no introduction of a sufficient amount of bubbles. The pigment high-concentration ink layer remains on the bottom surface of the ink tank.

  In this embodiment, there are four slopes on the inner wall of the ink tank. However, it is not always necessary to have four faces. If the structure is such that the ink bottom area is reduced and the pigment component that settles gathers on the bottom face, one face is 2. It doesn't matter in terms of surface. Further, the angle of the slope is not limited, and any angle may be used as long as the stagnation in the ink tank is reduced.

  Ink that does not contribute to the printing operation and recovery operation of the ink jet recording apparatus can be always supplied to the ink jet recording head without being discharged from the ink lead needle and discarded.

  Therefore, the density unevenness in the ink tank is alleviated, and a liquid with a constant density can be supplied from the ink supply port, and a high-quality print quality with no density difference can be obtained.

(Second embodiment)
In the first embodiment of the present invention, air bubbles are introduced from the air introduction needle at the bottom of the ink tank, but in the second embodiment, air is introduced into the bottom of the ink tank from the gas-liquid separation film, thereby The ink is agitated. This will be described below with reference to the drawings.

  FIG. 8 is a diagram for explaining a method of stirring the ink in which the pigment component in the ink tank has settled in the second embodiment. In FIG. 8, a hollow ink lead needle 39 for leading ink in the ink tank and a hollow air introduction needle 38 for introducing air into the ink tank are provided. These needles are respectively inserted into the first connection port 27 (illustrated in FIG. 5) and the second connection port 28 (illustrated in FIG. 5) of the ink tank, so that the ink supply unit 5 is connected to the inside of the ink tank. Communicate. The mesh member 51 is provided on the bottom surface of the inner wall of the ink tank. Here, the net-like member 51 is made of SUS. However, the material is not limited to this material as long as it is a mesh-like structure.

  Here, the air introduced from the air introduction needle generates bubbles 70b from the entire area of the mesh member 51, and pushes up the high-concentration layer ink settling on the bottom surface in the ink storage unit 14 to stir the ink. In addition, the ink density can be uniformly distributed.

  In addition, the air introduction ends when the meniscus force at the end of the air introduction needle 38 where the ink is in contact with the air and the pressure in the ink tank 11 are balanced.

  In addition, a large format ink is required for a wide format printer having a large ink supply amount per sheet and a network printer having a high operation rate. As the capacity of the ink tank increases, the bottom area of the ink tank increases, so that the ink tank of the present invention is more effective for stirring the settled pigment.

  By the way, the ink jet recording heads described in the first and second embodiments are ink jet recording heads that eject ink droplets by causing a change in state due to film boiling in ink using thermal energy. The same effect as in this embodiment can be obtained even in an ink jet recording apparatus that uses and discharges ink.

It is a figure explaining the stirring condition of the ink supply system to the inkjet recording head using the ink tank in 1st embodiment of this invention. It is a figure explaining the inkjet recording device which implements suitably the ink supply system in 1st embodiment of this invention. It is a perspective view of the ink storage container in the first embodiment of the present invention. It is a disassembled perspective view explaining the structural member of the ink storage container shown in FIG. FIG. 4 is a schematic diagram of an FF cross section of the ink storage container illustrated in FIG. 3. It is a figure explaining the ink supply condition of the ink supply system to the inkjet recording head using the ink tank in 1st embodiment of this invention. FIG. 8 is a schematic cross-sectional view illustrating an ink state when the ink tank illustrated in FIG. 7 is left in a stationary state for a long time. It is a figure explaining the stirring condition of the ink supply system to the inkjet recording head using the ink tank in 2nd embodiment of this invention. It is a figure explaining the stirring condition of the ink supply system to the inkjet recording head using the conventional ink tank. FIG. 4 is a schematic diagram of a GG cross section of the ink storage container shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording head 2 Carriage 3 Carrying roller 5 Ink suction unit 6 Ink supply tube 7 Recovery unit 8,9 Guide rail 11 Ink tank 12 Ink 12a Pigment low density ink layer 12b Pigment high density ink layer 14 Ink storage part 15a, 15b Cover DESCRIPTION OF SYMBOLS 16 Elastic member 17 Storage medium holder 18 Storage medium 19 Double-sided tape 20 Fixing member 21 Bottom cover 22 Lid fixing member 27 First connection port 28 Second connection port 29 Bottom surface 30 Slope 38 Ink lead needle 39 Atmospheric introduction needle 41 Ink lead-out Pipe 44 Air introduction pipe 51 Net member 65, 66 Air 70a, 70b Bubble E Arrow S Recording sheet

Claims (3)

In the ink storage container to be supplied to the inkjet recording apparatus,
An ink storage chamber for storing the ink;
An ink supply port provided at the bottom of the ink storage chamber wall for supplying the ink in the ink storage chamber to the outside;
An air inlet provided at the bottom of the ink storage chamber for introducing air into the ink storage chamber;
An ink storage container comprising: at least one inclined surface continuous to a bottom portion of the ink storage chamber.   The ink container according to claim 1, wherein an end portion of the atmosphere introduction port on the ink tank side is constituted by a mesh member. An ink supply system using the ink container according to claim 1,
An ink supply system comprising: an ink supply unit connected to the ink supply port; and an air introduction unit connected to the air introduction port.

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