JP2008179118A - Liquid injection apparatus and waste ink tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid injection apparatus capable of preventing deposition and fixation of an ink component in a waste ink tank, and the waste ink tank provided in the liquid injection apparatus, which enables high quality printing in the liquid injection apparatus. <P>SOLUTION: The liquid injection apparatus is provided with: a pump 3 for sucking waste ink injected to a capping apparatus 1 from an injection head 2; a main flow path (capping apparatus 1, and tubes 6a, 6b) for flowing the waste ink sucked by the suction of the pump 3 to a waste ink tank 14 from the capping apparatus 1; and a refilling flow path A for flowing an ink solvent component 20 to the waste ink flowing in the main flow path. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus and a waste ink tank, and more particularly to a technique for preventing accumulation and solidification of ink components in the waste ink tank.

  2. Description of the Related Art Conventionally, a serial printing type liquid ejecting apparatus includes an ejecting head that is mounted on a carriage and reciprocates in the width direction (main scanning direction) of a recording sheet, and a direction (secondary) that is perpendicular to the moving direction of the ejecting head. Paper feeding means for transporting in the scanning direction), and printing on recording paper by ejecting ink droplets from the ejection head based on print data.

  In such a liquid ejecting apparatus, the ink pressurized in the pressure generating chamber is ejected from the ejecting head as ink droplets onto a recording sheet, and printing is performed, so that the solvent component of the ink contained in the ink from the nozzle opening is evaporated. There is a problem that the nozzle opening is clogged due to an increase in ink viscosity, solidification of ink, adhesion of dust, mixing of bubbles, and the like, resulting in poor printing.

  For this purpose, this type of liquid ejecting apparatus includes a capping device 1 shown in FIG. 7 for sealing the nozzle surface of the ejecting head during non-printing. The capping device 1 includes a cap 1b made of a flexible resin that protrudes in the direction of the ejection head 2 from the four sides of a rectangular holder 1a, an absorbent material 1c, and a discharge pipe 1d. This capping device 1 not only functions as a lid for preventing the ink of the plurality of nozzle openings provided on the nozzle surface 2a of the ejection head 2 from being dried, but also in the case where clogging occurs in the nozzle openings. 1b comes into contact with the nozzle surface 2a to seal the nozzle surface 2a, and the pump 3 is driven to forcibly suck out and discharge ink from the nozzle opening, thereby providing a maintenance function for eliminating clogging of the nozzle opening. Yes.

  Forcible ink suction and discharge processing for eliminating clogging of the ejection head 2 is called a cleaning operation. For example, when the printing is resumed after a long pause of the liquid ejection apparatus, or when the user fails to print. It is executed when the cleaning switch is recognized and operated. It also has a maintenance function that eliminates clogging of the nozzle openings by applying a drive signal unrelated to printing to the ejection head 2 to cause ink droplets to be ejected idle, which is called a flushing operation. Yes. This flushing operation is performed, for example, in the capping device at regular intervals (for example, every 10 seconds) for the purpose of preventing clogging due to thickening of ink at a nozzle opening where there is little opportunity for ink droplet ejection during a printing operation. This is done by ejecting drops. Then, when the flushing operation is repeated and a predetermined amount of ink is accumulated in the capping device, an operation called an idle suction operation for discharging the ink in the capping is performed. This empty suction operation is performed in order to prevent the accumulated ink from overflowing from the capping device, and the pump is used in a state where the cap 1b is not in contact with the nozzle surface 2a, that is, the nozzle surface 2a is not sealed by the capping device. 3 is driven, and only the ink in the capping device is discharged without sucking ink from the nozzle opening.

  The waste ink 6 sucked and discharged by the pump 3 by executing the above-described cleaning operation and idle suction operation is disposed below the liquid ejecting apparatus via the capping device 1 serving as the main flow path and the tubes 6a and 6b. Discarded in the waste ink tank 4. In the waste ink tank 4, an absorbent material 5 is laid on a flat bottom 4 e of the waste ink tank 4, and the waste ink 6 is absorbed and held by the laid absorbent material 5. Further, the waste ink 6 absorbed by the absorbent 5 is configured to effectively use the substantial volume of the waste ink tank 4 by evaporating the ink solvent component by natural drying (Patent Document 1, etc.). .

JP 2003-285552 A

  However, recently, a liquid ejecting apparatus using a pigment-based ink in which a pigment is dispersed as a coloring material in an ink solvent component is also provided. This pigment-based ink has a problem that clogging is likely to occur in the absorbent material 5 when it is discarded in a waste ink tank, as compared with a dye-based ink that has been frequently used in the past. The reason is that not only a small amount of water and solvent components in the waste ink 6 evaporate and scatter (however, the solvent component having a moisturizing action, that is, the moisturizing component does not evaporate), so that the concentration of the pigment component having a large particle size becomes high, and the waste ink is discarded. This is because the viscosity of the ink 6 increases and it becomes difficult to penetrate the absorbent material 5 and clogging occurs. For this reason, in the pigment-based ink discarded in the waste ink tank 4, it is difficult for the pigment component to smoothly penetrate into the entire absorbent material 5, and it is easy to deposit and solidify on the surface of the absorbent material 5. Then, since the solidified ink does not spread over the entire absorbent material 5, the absorbent material 5 cannot hold a predetermined amount of ink, causing a problem that the discharged ink overflows from the waste ink tank to the outside. Further, when ink is further accumulated, as shown in FIG. 7, the ink is accumulated and solidified to the vicinity of the discharge port 6d of the tube 6b of the pump 3, and the tube discharge port 6d is blocked and the tube 6b is clogged. When the cleaning operation and the flushing operation are performed in spite of the clogged state of the tube 6b in the vicinity of the discharge port 6d of the tube 6b, the suction ability of the waste ink 6 by the pump 3 is reduced, resulting in the cleaning and flushing. Since nozzle clogging cannot be sufficiently removed, high-quality printing cannot be performed. These problems are likely to occur in pigment-based inks, but also occur in dye-based inks.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus that prevents the accumulation and solidification of ink components in a waste ink tank, and a waste ink tank provided in the liquid ejecting apparatus. An object is to enable high-quality printing in a liquid ejecting apparatus.

  In order to solve the above problems, a liquid ejecting apparatus of the present invention includes a pump that sucks waste ink ejected from the ejecting head to the capping device, and the waste ink from the capping device to the waste ink tank by the suction of the pump. And a replenishment flow path for allowing the solvent component of the ink to flow into the waste ink flowing through the main flow path.

  In this way, since the solvent component of the ink can be caused to flow into the waste ink flowing into the waste ink tank through the replenishment flow path, the waste ink tank generated due to the evaporation of the moisture and the solvent component of the waste ink by natural drying It is possible to prevent the accumulation and solidification of waste ink in the ink, prevent ink leakage from the waste ink tank, and in turn enable high-quality printing. It is also possible to prevent clogging of the main flow path that leads the waste ink to the waste ink tank.

  Here, the solvent component of the ink that flows into the replenishing flow path may be a solvent component contained in the waste ink guided into the waste ink tank. In this case, the solvent flowing into the replenishing flow path is the solvent component contained in the waste ink in the waste ink tank, so that the waste ink can be effectively used to prevent the viscosity of the waste ink from increasing.

  Furthermore, the solvent component contained in the waste ink may be a component obtained by filtering the waste ink using a predetermined filter in the waste ink tank. In this way, since the solvent component of the ink flowing into the replenishment flow path is the component filtered in the waste ink tank, only the solvent component from which the component causing the deposition is removed from the waste ink component can be replenished. The concentration of the component can be reliably increased.

  Further, the replenishing flow path is configured such that a solvent component contained in the waste ink guided to the waste ink tank flows into the main flow path by suction of the pump. According to this configuration, since the solvent component of the waste ink in the waste ink tank is caused to flow into the replenishment flow path by the pump that sucks the waste ink ejected to the capping device, it is possible to replenish without newly adding a pump. Become.

  Furthermore, it is preferable that the replenishment flow path causes the solvent component to flow into the main flow path between the capping device and the pump. In this way, the solvent component of the ink flowing in the replenishing flow channel is configured to flow into the main flow channel upstream of the pump that sucks the waste ink ejected to the capping device, so the waste ink guided to the waste ink tank The solvent component contained in the ink can be stably flowed into the waste ink by the suction force of the pump. In addition, since the solvent component contained in the waste ink can flow from the upstream of the main channel to almost the entire main channel, the thickening of the waste ink flowing through the main channel can be suppressed and the waste ink can be stably flowed. It becomes.

  Alternatively, the replenishment flow path may allow the solvent component to flow into the capping device. In this way, since the solvent component of the ink flowing in the replenishment flow channel flows into the capping device, the concentration of the solvent component in the capping device can be increased, and the moisture content of the solvent component that has flowed in increases the concentration in the capping device. Moisturizing ability can be increased.

  In the liquid ejecting apparatus according to the aspect of the invention, the waste ink tank may be configured such that a component having a higher specific gravity among the solvent components contained in the waste ink is accumulated on a bottom side of the waste ink tank, The solvent component of the ink flowing into the path includes a component having the heaviest specific gravity accumulated at the bottom of the waste ink tank. Many solvent components having a high specific gravity have a high moisture absorption rate for adsorbing moisture and have a large moisturizing effect. Therefore, by allowing the solvent component including the component with the highest specific gravity to flow into the waste ink, it is possible to compensate for water evaporated from the waste ink and to suppress the thickening of the waste ink.

  Here, the component having the heaviest specific gravity is preferably urea or glycerin. Urea and glycerin are suitable as solvent components for waste ink that flows into the main flow path because they are components having a high specific gravity among the solvent components of the ink and also have a high moisture absorption rate indicating the magnitude of the moisturizing action.

  Further, the present invention can be regarded as a waste ink tank. That is, a waste ink tank for storing waste ink ejected to a capping device, wherein a solvent component contained in the waste ink is stored through a predetermined filter from an absorbent material.

  According to the waste ink tank of the present invention, since the waste ink is collected from the absorbent material through the filter, the discharged ink is reliably received by the absorbent material, and the ink causes accumulation of components while preventing ink scattering. And a solvent component having a moisturizing action can be efficiently stored at a high concentration. The accumulated solvent component can be used or reused in the liquid ejecting apparatus of the present invention, for example.

  Here, in the waste ink tank, the absorber is laid on the surface side opposite to the bottom side of the waste ink tank, and the predetermined filter is laid on the bottom side of the waste ink tank with respect to the absorber. There may be. In this way, the absorbent material is placed on the bottom side of the waste ink tank with the filter facing down, and the waste ink is discharged to the surface side of the absorbent material. The components can suppress the accumulation and solidification of waste ink and prevent clogging of the filter.

  Further, the waste ink tank may be configured such that a component having a higher specific gravity among the solvent components contained in the waste ink is accumulated on the bottom side of the waste ink tank. By doing so, the solvent component accumulated at the bottom of the waste ink tank becomes the component with the highest specific gravity, so that the solvent component with the higher specific gravity can be easily taken out from the waste ink tank. Since the extracted solvent component has many components that absorb moisture and has a high moisture absorption rate, it can be used, for example, in the liquid ejecting apparatus of the present invention or reused as a solvent component of ink.

(Best Mode 1)
1 to 3 show a liquid ejecting apparatus according to the best mode 1, FIG. 1 is a perspective view showing an internal structure of the liquid ejecting apparatus, and FIG. 2 is a sectional view showing a solvent circulation device for waste ink of the liquid ejecting apparatus. 3 is a block diagram showing a control system of the liquid ejecting apparatus.

  The structure of the waste ink solvent circulation device will be described with reference to the drawings. The solvent circulation device includes a capping device 1, an ejection head 2, a pump 3, a waste ink tank 14, tubes 6a and 6b (including the capping device 1) as main flow paths, return tubes 6c and 6e as return paths, and a flow control valve. As a valve 10, a level sensor 21, and a control means 7.

  The waste ink tank 14 is formed of a box with an upper opening, and is mounted on the bottom side of the casing 15 of the liquid ejecting apparatus, for example. On the bottom 14e side of the waste ink tank 14, a two-layer treatment material 14A is laid with the filter 14a on the bottom and the absorbent material 14b on the top. One end of the waste ink tank 14 passes through the processing material 14A and faces the bottom 14e side of the waste ink tank 14, and the other end is connected to the upstream tube 6a of the pump 3 via the return tube 6e. A return tube 6c is provided. A valve 10 is interposed between the return tube 6c and the return tube 6e. That is, a feedback path is formed for mixing the solvent component 20 including the moisturizing component from the waste ink tank 14 into the tube 6a that forms the main flow path for guiding the waste ink sucked out from the ejection head 2 side to the waste ink tank 14. Return tubes 6c and 6e. A supply flow path A is configured by the return tubes 6c and 6e and the valve 10 as the return path. The main channel is a channel formed by the capping device 1, the tubes 6a, 6b, and the like.

  As shown in FIG. 3, the control means 7 controls the capping device 1, the ejection head 2, the carriage 8, the paper transport system 9, and the valve 10. That is, the control means 7 outputs a control signal 11 for controlling the capping device 1, the ejection head 2, the carriage 8, and the paper transport system 9, and opens and closes the valve 10 based on a signal from a level sensor 21 described later. The signal 12 is output.

  The level sensor 21 is installed on the bottom 14e side of the waste ink tank 14, and detects whether or not the amount of the solvent component 20 accumulated on the bottom 14e side of the tank has reached a predetermined height. A signal from the level sensor 21 is output to the control means 7.

  The filter 14a may be formed based on, for example, polystyrene foam, but may be a single activated carbon filter, a hollow dilute membrane filter, or a reverse osmosis membrane filter, or a multilayer of two or more. Alternatively, a special filter cloth in which fine porous urethane chips are processed into a film shape and embedded in the surface of the woven fabric of the base material, or a filter cloth for drainage gypsum using a polyester monofilament can be used. Accordingly, when pigment-based ink is used, the pigment is trapped (filtered), and the solvent component and the moisturizing component liquid from which the pigment has been removed are stored on the bottom 14 e side of the waste ink tank 14. Also when the dye-based ink is used, the dye is trapped and the solvent component liquid is stored on the bottom 14 e side of the waste ink tank 14.

  As the absorbent 14b on the filter 14a, activated carbon that adsorbs moisture on its surface, natural or synthetic silica, inorganic porous materials such as synthetic zeolite, sodium polyacrylate cross-linked body, starch-poly Known superabsorbent polymers such as acrylic acid graft polymer, hydrophilic polyurethane, or a copolymer of a monomer having a carboxylate, sulfonate or sulfate group and a monomer having a phosphate or phosphonate group, or moisture as a vapor Water-insoluble organic / inorganic hydrophilic gels such as silica gel that absorbs and swells as a liquid can also be used. In order to constitute the absorbent material 14b, these substances alone or a mixture of these substances are coated with a polymer having high water vapor permeability such as amorphous polyethylene, polystyrene, polypropylene, or a thin film made of the above polymer. What is necessary is just to shape | mold and lay as a sheet-like absorber of an area a little smaller than the bottom part 14e of the waste ink tank 14 by the method of wrapping. The polymer may have any composition, such as a single composition, a blend of a plurality of polymers, or a composition of a copolymer of a plurality of monomers.

  According to the above configuration, when the ejection head 2 is transported by the carriage 8 by the control means 7 and sent to the home position (standby position) and the capping device 1 is moved up and stopped, the cap 1b of the capping device 1 is stopped. When the tip 1t of the nozzle and the nozzle surface 2a of the ejection head 2 come into contact with each other, the nozzle surface 2a is covered with a cap 1b as a lid, and the nozzle opening is closed. With this function as a lid, it is possible to prevent clogging of the nozzle opening due to drying of ink adhering to the nozzle opening and intrusion of solid matter or dust into the nozzle opening. Alternatively, it is possible to perform flushing in which ink droplets are ejected from the nozzle opening in a state where the lid is covered. For each flushing operation, an empty suction operation by the pump 3 is performed.

  On the other hand, even during non-printing, if the ejection head 2 is in an uncapped state when the power is turned on, the control unit 7 moves the carriage 8 to the home position, stops the capping device 1 after moving it up, and then performs capping. After the apparatus 1 closes the nozzle surface 2 a side of the ejection head 2, the sealed space formed by the cap 1 b and the nozzle surface 2 a is sucked by the pump 3 to perform a cleaning operation. During the above-described empty suction operation or cleaning operation, waste ink is discharged from the discharge port 6d of the tube 6b onto the absorbent 14b of the waste ink tank 14 through the tubes 6a and 6b based on the suction operation of the pump 3. The waste ink is discharged onto the absorber 14b and then permeates into the absorber 14b. In this permeation process, the waste ink gradually spreads over the entire absorber 14b and descends to the filter 14a. A large particle size is trapped by the filter 14a, and the solvent component 20 including a moisturizing component having a small particle size is gradually accumulated on the bottom 14e side of the flat waste ink tank 14. When the solvent component 20 increases to a certain level at the bottom 14e of the waste ink tank 14 and is detected by the level sensor 21, the control means 7 opens the valve 10, so that the moisture retention accumulated on the bottom 14e side of the waste ink tank 14 is reached. The solvent component 20 including the components is sent to the tube 6a located upstream of the pump 3 via the return tubes 6c and 6e constituting the replenishment flow path A, and mixed with the waste ink sucked by the capping device 1. Is done. As a result, the concentration of the solvent component of the waste ink sucked by the waste ink tank 14 is increased, and the solvent component 20 containing a high concentration moisturizing component is discharged onto the absorbent 14b through the discharge port 6d of the tube 6b. The Therefore, it is possible to prevent a phenomenon in which the waste ink is smoothly absorbed by the absorbent 14b and the waste ink is deposited and solidified on the absorbent 14b. In addition, since a sufficient amount of ink can be held in the absorber 14b, it is possible to prevent the ink from overflowing from the waste ink tank 14 to the outside. That is, since the solvent component 20 including the moisturizing component from the return route by the return tubes 6c and 6e flows into the waste ink ejected from the capping device 1 to increase the solvent concentration, is the amount of water evaporation suppressed? Alternatively, even if water evaporates, the ratio is small, so that the viscosity does not increase much. Accordingly, the waste ink discharged to the waste ink tank 14 is less likely to be clogged by the absorption material 14b in the absorption and permeation process of the absorption material 14b, and is smoothly absorbed and spread over the entire absorption material 14b. It is possible to prevent waste ink from being accumulated and solidified by the waste ink pigment and dye discharged from the discharge port 6d of 6b and clogging of the absorbent 14b. Furthermore, since the absorbing material 14b can hold a predetermined amount of ink, the problem that the ink overflows from the waste ink tank 14 can be solved. This will be described in detail for the case of using pigment-based ink and dye-based ink.

  In the case of pigment-based inks, for example, a penetrating agent such as acetylene glycol is blended to improve penetrability, and pigment particles are dispersed on an aqueous medium using a dispersing agent such as various surfactants and aqueous resins. Thus, the pigment particle surface is easily wetted with water. Dispersion stability is ensured by using water, a non-volatile organic solvent, a lower alcohol or the like as the aqueous medium. Alternatively, there are those in which sulfonic acid groups are introduced on the surface of pigment fine particles. As described above, the pigment-based ink includes various solvent components (including a moisturizing component) in addition to the pigment.

  When the pigment-based ink is sucked by the pump 3, it is discharged to the waste ink tank 14 and absorbed by the absorbent material 14b. The waste ink is absorbed by the absorbing material 14b and gradually spreads while penetrating the entire absorbing material 14b, and then drops to the filter 14a by gravity. The pigment (pigment component) having a large particle size is trapped by the filter 14 a, and the solvent component 20 including the moisturizing component having a small particle size is filtered through the filter 14 a and gradually accumulates at the bottom 14 e of the waste ink tank 14.

  Accordingly, the solvent component 20 containing the accumulated moisture retention component returns to and flows into the upstream of the pump 3 via the return tubes 6c and 6e, and flows from the solvent component 20 and the capping device 1 through the tube 6a. Waste ink is mixed, and the concentration of the solvent component and the moisturizing component of the waste ink can be increased. The moisturizing component in the solvent component has a characteristic of taking in water in particular, so that it is possible to reduce water evaporation of the waste ink and to prevent thickening of the waste ink, and the waste ink is placed on the absorbent material 14b in a “smooth” state. Since the ink can be discharged, the waste ink is smoothly absorbed by the absorbent material 14b, so that clogging by the absorbent material 14b can be prevented, and the accumulation and solidification of the pigment on the absorbent material 14b can be prevented. As a result, blockage and clogging at the discharge port 6d of the tube 6b can be prevented, and high-quality printing is possible.

  Further, according to the present embodiment, the evaporation of moisture can be suppressed and the waste ink can be maintained in a “smooth” state, so that not only the waste ink pigment does not accumulate and solidify at the discharge port 6d of the tube 6b. By increasing the moisturizing component in the solvent component, the pigment component can be stabilized, and this also prevents the pigment component from being deposited and solidified in the waste ink. In addition, since a solvent component containing a large amount of moisturizing component can be stored in the bottom portion 14e of the waste ink tank 14, the moisturizing power on the processing material 14A side can be enhanced by the solvent component 20 including the stored moisturizing component, and the processing material 14A. Clogging can be prevented, and the service life can be extended.

  Furthermore, in this embodiment, even if the pigment component is deposited and solidified on the absorbent material 14b, the solvent component having a high “smoothness” concentration is sprinkled on it. The solidified material can be melted, and clogging of the treatment material 14A can be effectively suppressed. Furthermore, since the predetermined amount of ink can be held by the absorbent material 14b, the problem that the ink overflows from the waste ink tank 14 can be solved.

  The same applies to dye-based inks. That is, the waste ink is discharged into the waste ink tank 14 by the pump 3, discharged onto the absorbent material 14b, spreads throughout the process of being absorbed by the absorbent material 14b, and then filtered by the filter 14a. Solvent components such as glycerin and urea gradually accumulate on the bottom 14e side.

  In this embodiment, since the solvent component 20 including the moisturizing component returns to the upstream side of the pump 3 via the return tubes 6c and 6e, the solvent component 20 is mixed into the waste ink sucked from the capping device 1. Since the concentration of the solvent component or the moisturizing component of the waste ink is increased, the waste ink becomes a “sarabashi” waste liquid and is therefore efficiently absorbed by the absorbent 14b. Therefore, the waste near the discharge port 6d of the tube 6b. Accumulation and solidification of ink pigments and dyes can be prevented and clogging will not occur. In addition, since the predetermined amount of ink can be held by the absorbing material 14b, the problem that the ink overflows from the waste ink tank 14 can be solved.

  According to this embodiment, when the solvent component 20 including the moisturizing component accumulated in the bottom 14 e of the waste ink tank 14 reaches a certain level, the valve 10 is opened so that the solvent component 20 is returned to the upstream side of the pump 3. As a result, it is possible to prevent idle suction and to prevent a reduction in the suction capacity of the pump 3 due to idle suction.

(Best Mode 2)
In the best mode 1, the level sensor 21 is used to prevent idle suction. However, the accumulated amount of the solvent component of the ink can be estimated from the number of rotations of the pump 3 and the operation time. It is possible to omit the level sensor 21 by opening the valve 10 when the value reaches the set value.

(Best Mode 3)
In the best mode 1, only one return tube 6c for sucking the solvent component 20 accumulated in the bottom 14e of the waste ink tank 14 is provided. However, as shown in FIG. The replenishment flow path A may be configured by providing two or more return tubes 6c so as to suck portions separated from each other. According to this configuration, the solvent component 20 can be sucked more effectively, and even if one return tube 6c is clogged, suction can be performed by the other return tube 6c, and the reliability can be further improved.

(Best Mode 4)
In the best mode 1, the bottom portion 14e of the waste ink tank 14 has been described as a flat surface. However, as shown in FIG. 4, the bottom portion 14e in the vicinity of the suction port 6x of the return tube 6c is recessed to form a solvent reservoir portion 14x. May be. According to this configuration, since a large amount of the solvent component 20 can be captured in the solvent reservoir 14x, the solvent component 20 can be returned at an early stage, and effective measures for preventing clogging at an early stage can be effectively taken. Can do.

(Best Mode 5)
Further, as shown in FIG. 5, an auxiliary feedback tube 6f is connected to a return tube 6e constituting the replenishment flow path A, and the capping device 1 also includes a solvent component 20 including a moisturizing component by this auxiliary feedback tube 6f. If the part is returned, the moisture retention capability in the sealed space of the capping device 1 can be increased, and the evaporation of ink moisture and solvent components from the ejection head 2 can be more effectively prevented. That is, the water and solvent components of the ink contained in the printer ink evaporate from the portion exposed to the outside air (also referred to as meniscus) through the nozzles. Due to the evaporation of the ink solvent, the ink thickens or the color material density increases. Such a tendency also occurs during capping. Therefore, when the capping is performed, the solvent component 20 is fed back and stored in the capping device 1 so that the moisture retention capacity in the sealed space is enhanced, and the amount of ink moisture and solvent component evaporated during capping is further increased. It can be effectively suppressed. And since the density | concentration of the solvent component in a sealed space and a moisture retention component can be raised, clogging of the capping apparatus 1 itself can also be suppressed. Further, it is possible to prevent the ink from overflowing from the waste ink tank 14.

  In addition, when the solvent component 20 including the moisturizing component does not easily flow through the auxiliary feedback tube 6f toward the capping device 1 due to the suction of the pump 3, a valve (not connected) is provided between the tube 6a and the auxiliary feedback tube 6f in the feedback tube 6e. It is preferable to close the flow path of the return tube 6e so that all the solvent component 20 including the moisturizing component to flow to the return tube 6e flows to the capping device 1.

(Best Mode 6)
In the best mode 1, the configuration in which a part of the waste ink in the waste ink tank 14 is returned and introduced to the upstream side of the pump 3 using the suction force of the pump 3 has been described. However, the present invention is limited to this. First, as shown in FIG. 6, for example, a manual pump 30 such as a bellows type pump is provided, and the solvent component 20 of waste ink is stored in the auxiliary tank 31 by the manual pump 30, and the valve 10 is used when necessary. And the replenishment flow path A may be configured to return the solvent component 20 to the upstream side of the pump 3. In FIG. 6, reference numeral 32 denotes a check valve. By repeatedly pumping, the solvent component 20 in the waste ink tank 14 can be sucked through the return tube 6 c and stored in the auxiliary tank 31. In the auxiliary tank 31, a treatment material 14B provided with an absorbent material 14m above and a filter 14n below is laid.

(Best Mode 7)
In the best mode 1, the treatment material 14A having a two-layer structure in which the filter 14a is laid on the absorber 14b of the waste ink tank 14 is provided. However, the present invention is not limited to this, and the single-layer structure in which the filter 14a is not provided. The processing material may be used. Or you may comprise a processing material only with the filter 14a. Or you may use the processing material of the three-layer structure which laid the filter 14a under the absorber 14b, and the absorber 14b under this filter 14a, or the filter under it.

(Best Mode 8)
In the best mode 1, the return tube 6c is inserted from the upper side of the drawing to a predetermined depth so as to reach the liquid layer of the solvent component 20 accumulated to a certain level at the bottom 14e of the waste ink tank 14, but the waste ink tank 14 The return tube 6c may be disposed so as to suck the solvent component accumulated at the bottom of the bottom 14e. In this case, the bottom portion of the waste ink tank is preferably configured so that the solvent component having the heaviest specific gravity is theoretically accumulated at the bottom by gravity. This embodiment will be described with reference to FIG.

  FIG. 8A shows a state in which the place where the return tube 6c is inserted into the waste ink tank 14 is changed in the best mode 1 described above, and shows one embodiment of this mode. is there. The configuration other than the waste ink tank 14 and the return tube 6c is the same as that of the best mode 1 (see FIG. 2), and is not shown here and other configurations are omitted.

  As shown in FIG. 8A, the return tube 6c is disposed on the side surface of the waste ink tank 14 so that the solvent component existing on the same surface as the bottom portion 14e of the waste ink tank 14 can be sucked. Yes. Therefore, of the solvent component 20 that has passed through the filter 14a from the absorber 14b, the solvent component that has accumulated in the bottom 14e of the waste ink tank 14 flows and is sucked into the return tube 6c as indicated by the broken line arrow in the figure. It is.

  Here, in this embodiment, urea (specific gravity 1.3) and glycerin (specific gravity 1.22) are included as the solvent component 20. Of course, at least one of urea and glycerin may be included. In addition to these, the solvent component 20 includes triethylene glycol (specific gravity 1.13), triethanolamine (specific gravity 1.12), 2-pyrrolidone (specific gravity 1.09), triethylene glycol monobutyl ether (specific gravity 0. 99) and 1,2-hexanediol (specific gravity 0.97) are used, but the specific gravity is lighter than urea and glycerin. Urea and glycerin are also moisturizing components having a high moisture absorption rate of 100% by weight and 250% by weight at 25 ° C. and a relative humidity of 100%, respectively. Therefore, in the waste ink tank 14, as shown in the figure, the solvent component of the urea / glycerin layer that accumulates on the bottom 14 e side of the waste ink tank 14 that is below the other solvent component layer due to the specific gravity is returned to the return tube. If the waste ink flowing through the main flow path is caused to flow through 6c, the thickening of the waste ink can be suppressed. As a result, the waste ink is smoothly absorbed by the absorbent material 14b, so that clogging by the absorbent material 14b can be prevented, and the accumulation and solidification of the pigment on the absorbent material 14b can be prevented.

  In the embodiment shown in FIG. 8A, the bottom shape of the waste ink tank 14 is shown in FIG. 8 (FIG. 8) in order to ensure that the solvent components of the urea and glycerin layers further accumulate at the bottom of the waste ink tank. It is preferable to form it diagonally as shown in b). In this way, even when the amount of urea and glycerin accumulated is small, the probability that the urea and glycerin will flow into the return tube 6c is increased without the flow of other solvent components.

  Of course, the method of disposing the return tube 6c in the waste ink tank 14 is not limited to the disposition on the side as shown in FIGS. 8 (a) and 8 (b). As shown in FIG. 9, the waste ink tank 14 may be disposed on the bottom 14 e side. In this way, it is possible to reliably flow the solvent component accumulated at the bottom to the return tube 6c. When the return tube 6c is disposed at the bottom as described above, although not shown, the bottom shape of the waste ink tank 14 is formed in a conical funnel shape, and the return tube 6c is disposed at the center of the cone. Is preferred. In this way, it is possible to flow the solvent component accumulated at the bottom of the waste ink tank 14 to the return tube 6c more reliably.

The perspective view which shows the internal structure of a liquid ejecting apparatus (the best form 1). Sectional drawing which shows the solvent circulation apparatus of the waste ink of a liquid ejecting apparatus (the best form 1). The block diagram which shows the control system of a liquid ejecting apparatus (best form 1). Sectional drawing which shows the solvent circulator of the waste ink of a liquid ejecting apparatus (best form 3, 4). Sectional drawing which shows the solvent circulation apparatus of the waste ink of a liquid ejecting apparatus (best form 5). Sectional drawing which shows the solvent circulation apparatus of the waste ink of a liquid ejecting apparatus (best form 6). Sectional drawing which shows the solvent circulation apparatus of the waste ink of the conventional liquid ejecting apparatus. (A)-(c) is sectional drawing which shows the structure of a waste ink tank (best form 8).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Capping apparatus, 2 ... Jet head, 3 ... Pump, 14 ... Waste ink tank, 14e ... Bottom part, 14a ... Filter, 14b ... Absorber, 6a, 6b ... Tube (main flow path), 6c, 6e ... Return tube ( Return path), A ... Supply channel.

Claims (11)

A pump for sucking the waste ink ejected from the ejection head to the capping device;
A main flow path for flowing the waste ink from the capping device to a waste ink tank by suction of the pump;
A replenishment flow path for allowing the solvent component of the ink to flow into the waste ink flowing in the main flow path;
A liquid ejecting apparatus comprising:   The liquid ejecting apparatus according to claim 1, wherein the solvent component of the ink flowing into the replenishing flow path is a solvent component contained in the waste ink guided into the waste ink tank.   The liquid ejecting apparatus according to claim 2, wherein the solvent component contained in the waste ink is a component obtained by filtering the waste ink using a predetermined filter in the waste ink tank.   3. The replenishing flow path is configured such that a solvent component contained in the waste ink guided to the waste ink tank flows into the main flow path by suction of the pump. 4. The liquid ejecting apparatus according to 3.   5. The liquid ejecting apparatus according to claim 4, wherein the replenishing flow channel causes the solvent component to flow into the main flow channel between the capping device and the pump.   The liquid ejecting apparatus according to claim 2, wherein the replenishing flow channel allows the solvent component to flow into the capping device. The waste ink tank is configured such that, among solvent components contained in the waste ink, a component having a higher specific gravity accumulates on the bottom side of the waste ink tank,
7. The liquid ejecting apparatus according to claim 2, wherein the solvent component of the ink flowing into the replenishing flow path includes a component having the heaviest specific gravity accumulated at a bottom portion of the waste ink tank. .   The liquid ejecting apparatus according to claim 7, wherein the component having the highest specific gravity is urea or glycerin.   A waste ink tank for storing waste ink ejected to a capping device, wherein a solvent component contained in the waste ink is stored from an absorbent through a predetermined filter.   The absorbent material is laid on the surface side opposite to the bottom side of the waste ink tank, and the predetermined filter is laid on the bottom side of the waste ink tank with respect to the absorbent material. The waste ink tank according to 9.   11. The waste ink tank according to claim 9, wherein among the solvent components contained in the waste ink, a component having a higher specific gravity is accumulated on the bottom side of the waste ink tank. Waste ink tank.

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