JP2008062430A - Waste ink tank, and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To build up a waste ink system having a high reliability which does not need to install a space for holding a waste ink more than required for a viscosity-increased and easy-to-harden pigment ink which is hardly absorbed by an absorber, and also, prevents the ink from leaking into the apparatus, and the motion of the apparatus from being obstructed. <P>SOLUTION: This waste ink tank is formed into an approximately empty cavity, and a glycerin is prepared inside as a spreading liquid in order to prevent the viscosity increase to a degree in which the fluidity of the ink remarkably falls. Then, a connecting section with a feeding unit is installed as an atmosphere communicating port in addition to a connecting section with a recovering unit, and areas other than the connecting sections are sealed. Then, the absorber for preventing an ink leakage from occurring is installed directly under the atmosphere communicating section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to a waste ink tank that stores waste ink collected from an ink jet recording head.

  An image forming apparatus adopting an ink jet method is used in a printer, a copier, a facsimile, or the like because it has low noise and low running cost, is easy to be miniaturized, and is easily colored.

  However, the image formation by this ink jet recording method has the following inherent problems. That is, first, since an image is formed by ejecting droplets of ink or the like from an inkjet head onto a print medium such as paper or an OHP film, a sub-scan is performed along with the droplet ejection operation from the inkjet head to the print medium. Next, when fine droplets (mist) are generated or the droplets bounce off and adhere to the vicinity of the ejection port of the inkjet head, the normal ejection of the droplets is hindered and an unexpected direction In some cases, the liquid droplet may be deflected, or in the worst case, the liquid droplet may not be ejected. Such a problem is that if the liquid droplets are not ejected from the ink jet head, a part of the liquid held in the ink jet head evaporates to increase its viscosity, or in the worst case solidify. When the discharge operation is performed, the liquid droplets are deflected in an unexpected direction, or the liquid droplets cannot be discharged.

  In order to cope with such problems inherent to the inkjet head system, the ejection port surface of the inkjet head is periodically wiped to remove droplets and foreign matter adhering thereto, or the inkjet head performs an ejection operation. When the ink jet head is not in a so-called non-printing state, the ejection port surface of the ink jet head is covered with a capping member in an airtight state to prevent evaporation of the liquid interposed in the ink jet head. If the viscosity of the liquid in the ink jet head increases or is solidified even after such capping operation, the inside of the ink jet head is forcibly forced by a suction pump through the capping member. By sucking, the liquid whose viscosity is increased or in a semi-solid state is discharged from the ink-jet head, so that the liquid discharge state from the liquid discharge head is kept good. These processes are all known as recovery processes.

  The liquid sucked from the inkjet head by the suction pump, that is, the waste ink, is permeated and held in a porous waste ink absorber such as a fiber bundle or continuous foamed resin accommodated in the waste ink tank. This waste ink absorber is composed of the number of defective prints, the number of recovery processes, the amount of waste ink discharged from the inkjet head by one recovery operation, and the fine droplets (mist) generated with the droplet discharge operation. The volume is determined according to the amount of the amount. On the other hand, when considering the image forming apparatus as a whole, it can be expected that reducing the volume of the waste ink absorber is not limited by the installation location and the like, and the cost is reduced. However, if the volume of the waste ink absorber is made too small with respect to the required volume of the waste ink absorber, maintenance waste such as necessity of periodically replacing the waste ink absorber occurs.

  On the other hand, when a color image is formed on a print medium such as paper by an ink jet method, it has been pointed out that ink bleeds between black ink and other color inks, resulting in deterioration of image quality. In order to solve such problems, a technique has been proposed in which black ink and other color inks are chemically reacted on a print medium to suppress color bleeding by suppressing ink flow. Yes. Further, in a text document or the like, black ink containing a pigment component has been used in order to improve the quality of characters printed with black ink.

  In an image forming apparatus using ink having such characteristics, the waste ink itself has a property of being easily thickened or solidified, so that the permeability to the waste ink absorber is poor, and the waste ink absorber is entirely discarded. It becomes difficult to diffuse the ink.

  In order to solve these problems, in the prior art, the waste ink absorber is two-dimensionally arranged over the entire bottom surface of the image forming apparatus, and two types of absorbers are provided, with black ink on one side, The other side is configured to absorb the color ink (see, for example, Patent Document 1).

  Hereinafter, a conventional waste ink tank will be described with reference to FIGS.

  On one scanning movement end side of the carriage 13, a recovery unit 21 constituting a part of the recovery means is disposed adjacent to the side of the platen 20, and the recovery unit 21 is disposed on the ejection port surface 14 of the head unit 11. Can be moved up and down in the opposite direction. The recovery unit 21 is provided with a pair of capping members 22 and 23 that cover the discharge port surface 14 of the head unit 11 at the rising end position, and one of the capping members 22 discharges pigment-based black ink. Covering the ejection port group, and the other capping member 23 collectively covers the three ejection port groups that eject the dye-based color ink, so that a part of the ink is ejected from the ejection port of the head unit 11 during non-printing. It evaporates and dries and prevents the ink interposed in the head unit 11 from thickening and solidifying. Waste ink guide rods 24 and 25 are connected to the pair of capping members 22 and 23, respectively, and the thickened ink or the like interposed in the ink path communicating with the ejection port in the head unit 11 is capped members 22 and 23. Is sent to the waste ink tank 26 through the waste ink guide rods 24 and 25.

  A waste ink tank 26 disposed immediately below the recovery unit 21 so as to face the lower ends of the waste ink guide rods 24 and 25 extends over almost the entire lower surface of the ink jet printer, and mainly waste ink of color ink. A low-density first absorber 27 that permeates and holds the ink, a high-density second absorber 28 that permeates and holds the waste ink of the black ink, and a storage container that stores the first and second absorbers 27 and 28 29 is the main part. The container 29 in the shape of a rectangular dish has a flat rectangular bottom plate portion 30 substantially corresponding to the planar projection shape of the ink jet printer and a side wall portion 31 surrounding the flat bottom plate portion 30. The second absorbent body 28 has a rectangular thin plate shape that occupies a region slightly more than half of the bottom plate portion 30. The first absorber 27 having a dimension that extends over the entire area of the bottom plate portion 30 includes a thick portion 27S that occupies a region that is almost a half of the bottom plate portion 30 and a thin portion 27R that overlaps the second absorber 28. And the thick-walled portion 27S is lightly compressed and accommodated in the accommodating container 29 so as to come into contact with the surface of the bottom plate portion 30 together with the second absorber 28.

  The thin-walled portion 27R and the second absorber 28 of the first absorber 27 have openings extending from directly above the lower end of one waste ink guide rod 24 from which black ink waste ink is discharged to the surface of the bottom plate portion 30 of the container 29. 5 and the guide groove 33 extending from the opening 32 toward the right side in FIG. 5, that is, the other end side in the scanning direction of the carriage 13, and toward the lower side in FIG. Is formed. Further, the lower end of the other waste ink guide rod 25 from which the color ink waste ink is discharged is in a state of facing the upper end surface of the thin portion 27R of the first absorber 27 located on the side of the opening 32. ing.

Therefore, the black ink waste ink that tends to thicken or solidify due to the presence of the pigment is directly dropped from the opening 32 onto the bottom plate 30 of the storage container 29, and then planarly along the bottom plate 30 of the storage container 29. And diffused and held in the low-density second absorber 28. On the other hand, the waste ink of the color ink having good penetrability is dropped onto the surface of the thin portion 27R of the high-density first absorber 27 and permeated and held throughout the first absorber 27. Therefore, it becomes possible to permeate and hold the waste ink in the absorber without causing the reacting black ink and color ink to react in the waste ink absorber.
Japanese Patent Laid-Open No. 2003-80739 (page 8, FIG. 1)

  However, in the above conventional example, in order to prevent the ink from bleeding, the drying speed is changed to one that is easy to solidify, and the speed at which the ink thickens and solidifies faster than the speed at which the ink is absorbed by the absorber. In this case, the waste ink accumulates under the recovery unit that collects the waste ink without being absorbed by the absorber. As a result, the waste ink absorber has sufficient absorption capacity, and even though all of it does not absorb waste ink, waste ink overflows inside the image forming device, and the inside of the device can be soiled, causing abnormal operation. There is a problem of having sex.

  In order to prevent this trouble, as a method different from the conventional technique, there is a method of making the waste ink tank hollow as shown in FIG. 3 and holding the waste ink there, but if the ink is easy to thicken and solidify, It is experimentally known that the speed at which the ink dries and thickens faster than the speed at which the ink spreads inside the waste ink, and the waste ink 41 accumulates vertically at the bottom of the recovery unit as shown in FIG. . For this reason, although there is sufficient space in the waste ink tank, it becomes impossible to hold the waste ink inside the waste ink tank, and there is a problem that it leaks out of the waste ink tank and stains the inside of the apparatus. Further, there is a method of taking a large space in the downward direction of the recovery unit and using that portion as a waste ink tank. However, this causes a problem that the image forming apparatus is unnecessarily enlarged. Further, even if the size is limited to a certain extent and periodically exchanged, not only maintenance is complicated, but there is an unnecessary space on the bottom surface of the image forming apparatus other than the waste ink tank. There is also a problem of enlarging the device.

In order to solve the above problems, the ink jet recording apparatus of the present invention comprises:
The waste ink tank is almost hollow, and glycerin is provided as a diffusion liquid in order to prevent thickening until the fluidity of the ink drops significantly. In addition to the connection portion with the recovery unit, a connection portion with the supply unit is provided as an air communication port, and the other portions are sealed.

  In order to prevent ink leakage from the image forming apparatus during secondary transportation or the like, an absorber for preventing leakage is provided in the vicinity of the connecting portion with the supply unit that also functions as an air communication port.

  Since it is possible to prevent thickening of the waste ink until the fluidity of the waste ink disappears, it is possible to provide a waste ink tank without any space in the lower part of the recovery unit, thereby reducing the size of the image forming apparatus. Is possible. In addition, because waste ink can be stored without using an absorber, the waste ink tank can be made smaller than the case of using an absorber, and the cost can be reduced with respect to the amount of waste ink. Is possible.

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

  FIG. 1 is a perspective view showing a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention.

  The ink jet recording apparatus shown in FIG. 1 repeats the reciprocating movement (main scanning) of the recording head 11 and the conveyance (sub scanning) of recording media P such as general recording paper, special paper, and OHP film at a predetermined pitch. This is a serial type recording apparatus that forms characters, symbols, images, and the like by selectively ejecting ink from the recording head 11 in synchronization with these movements and attaching them to the recording medium P.

  In FIG. 1, a recording head 11 is detachably mounted on a carriage 13 that is slidably supported by two guide rails 15 and is reciprocated along the guide rails 15 by driving means such as a motor (not shown). Yes. The recording medium P is opposed to the ink ejection surface of the recording head 11 by the transport roller 35 and crosses the moving direction of the carriage 13 so as to maintain a constant distance from the ink ejection surface (for example, It is conveyed in the direction of arrow A, which is a direction orthogonal to each other.

  The recording head 11 has a plurality of nozzle rows for ejecting ink of different colors (four colors of black, cyan, magenta, and yellow in this embodiment). A plurality of independent main tanks 12 are detachably attached to the ink supply unit 36 corresponding to the color of ink ejected from the recording head 11. The ink supply unit 36 and the recording head 11 are connected to each other by a plurality of ink supply tubes 10 corresponding to the colors of the ink, and the main tank 12 is mounted on the ink supply unit 36 so that the ink is stored in the main tank 12. Each color ink can be independently supplied to each nozzle row of the recording head 11.

  The black ink in this embodiment uses a pigment-based ink that tends to thicken or solidify, while the other color inks, that is, cyan ink, magenta ink, and yellow ink are dye-based inks. It is used so that black ink and color ink react chemically, and color blur does not occur much even when they are mixed.

  A recovery unit 21 is disposed so as to face the ink ejection surface of the recording head 11 in a non-recording area that is within the reciprocating range of the recording head 11 and outside the passing range of the recording medium P. Yes.

  Next, the waste ink tank 26 of this embodiment will be described with reference to FIG.

  The recovery unit 21 can be moved up and down in a direction opposite to the discharge port surface of the recording head 11, and the recovery unit 21 is provided with a capping member that covers the discharge port surface of the recording head 11 at the rising end position. In addition, when ink is not printed, a part of the ink is evaporated and dried from the ejection port of the recording head 11 to prevent the ink interposed in the recording head 11 from being thickened and solidified. A waste ink guide rod 24 is connected to the capping member, and a suction pump (not shown) housed in the recovery unit 21 is interposed in the middle of the waste ink guide rod 24. This suction pump puts the inside of the recording head 11 into a negative pressure state during the suction recovery processing of the recording head 11, thereby increasing the viscosity of the ink that is interposed in the ink path (not shown) that communicates with the ejection port of the recording head 11. From the capping member to the waste ink tank 26 via the waste ink guide rod 24.

  The waste ink tank 26 disposed immediately below the recovery unit 21 so as to face the lower end of the waste ink guide rod 24 is located below the recovery unit 21 and the ink supply unit 36, and the size of the waste ink tank 26 is as follows. The amount of waste ink for the life of the ink jet recording apparatus after drying is large enough to be retained. The waste ink guide rod 24 and the waste ink tank 26 are jointed without leaking, and even when the waste ink tank 26 is turned upside down, it does not leak from the joint portion. Further, the ink supply unit 36 is configured to guide the leaked ink to the waste ink tank 26 through the waste ink guide rod 37, and the waste ink that has passed through the waste ink guide rod 37 is absorbed and held in the absorber 38. It becomes the composition which is done. Here, the black ink is difficult to be absorbed by the absorber, but it is very rare that the ink leaks from the ink supply unit 36, and since the amount is small, it is deposited on the top of the absorber. There is no problem. In addition, the waste ink guide rod 37 and the waste ink tank 26 are not jointed in a sealed system, and the joint portion communicates with the waste ink tank 26 and the atmosphere, thereby speeding up drying of the waste ink inside and increasing the temperature. Even when a change or a change in atmospheric pressure occurs, the pressure inside the waste ink tank is made equal to the atmospheric pressure to prevent the backflow of the waste ink.

  In this embodiment, the waste ink guide rod 37 and the waste ink are utilized by taking advantage of the characteristic that the black ink used is not easily absorbed by the absorber and the thickened ink is difficult to be absorbed by the absorber. An absorber is provided immediately below the atmosphere communication portion of the joint portion with the tank 26 so that waste ink does not leak even if the main body is turned upside down. The waste ink guide rod 37 is provided for four colors, and all have the same configuration. FIG. 2 shows one color.

  Further, in the waste ink tank 26, glycerin is put as a diffusion liquid so that the waste ink does not accumulate immediately below the recovery unit 21 as shown in FIG. The amount of the glycerin is set to a minimum amount capable of maintaining the fluidity (viscosity) spreading throughout the waste ink tank 26 without the thickened ink accumulating vertically, and in this embodiment, the total waste ink. Approximately 10% of the amount is included. By minimizing the amount of glycerin, the size of the waste ink tank 26 can be reduced.

  Further, in this embodiment, since the connection portion with the ink supply unit is used as an air communication port, a system that is not sealed from the outside is used. However, the connection portion between the ink supply unit and the waste ink tank is also a recovery unit. Similarly to the connecting portion, the air communication port may be sealed and a separate air communication port may be provided in the waste ink tank. In that case, you may take the structure which uses a gas-liquid exchange film | membrane for an air | atmosphere communicating port part.

  Furthermore, as another embodiment, a configuration may be adopted in which raw glycerin is not placed in the waste ink tank, but an absorber that has absorbed glycerin is placed in the waste ink tank.

  By adopting the above configuration, waste ink that minimizes the size of the waste ink tank, supports ink that is difficult to be absorbed by the absorber, and ensures device reliability such as ink leakage during transportation of the main body. It becomes possible to propose a system.

  Further, the waste ink tank has been described so far with a capacity corresponding to the life of the main body, but the present invention can be applied to a waste ink tank of a type that is replaced when a certain amount is accumulated.

1 is a perspective view illustrating a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is the schematic of the waste ink tank of the inkjet recording device by one Embodiment of this invention. It is the schematic of a waste ink tank when a malfunction occurs. It is the schematic for demonstrating the structure of an example of the waste ink tank in the conventional inkjet recording device. It is the schematic for demonstrating the structure of an example of the waste ink tank in the conventional inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ink supply tube 11 Recording head 12 Main tank 13 Carriage 15 Guide rail 21 Recovery unit 24, 37 Waste ink guide rod 26 Waste ink tank 35 Conveyance roller 36 Ink supply unit 38 Absorber 40 Glycerin 41 Waste ink (fixed matter)

Claims (10)

In an ink jet recording apparatus comprising: a collecting unit that collects waste ink discharged from a recording head; and a waste ink tank that stores the waste ink collected by the collecting unit.
The waste ink tank has a communication part for introducing the waste ink and an opening part communicating with at least one atmosphere, and has glycerin inside as a diffusion liquid for diffusing the introduced waste ink. A waste ink tank characterized by The waste ink tank according to claim 1, wherein the waste ink tank has an absorber in the vicinity of the introduction portion for introducing the waste ink and in the vicinity of the opening communicating with the atmosphere. 2. The waste ink tank according to claim 1, wherein the opening communicating with the atmosphere also serves as an introduction portion for flowing ink leaking from the ink supply unit to the waste ink tank. The waste ink tank according to claim 1, wherein the ink jet recording apparatus includes a black ink or other ink containing a pigment. The waste ink tank according to claim 1, wherein a gas-liquid exchange membrane is used in an opening communicating with the atmosphere. In an ink jet recording apparatus comprising: a collecting unit that collects waste ink discharged from a recording head; and a waste ink tank that stores the waste ink collected by the collecting unit.
The waste ink tank has a communication part for introducing the waste ink and an opening part communicating with at least one atmosphere, and has glycerin inside as a diffusion liquid for diffusing the introduced waste ink. An ink jet recording apparatus having a waste ink tank. The ink jet recording apparatus having a waste ink tank according to claim 6, wherein the waste ink tank has an absorber in the vicinity of an introduction portion for introducing waste ink and in the vicinity of an opening communicating with the atmosphere. The inkjet recording apparatus having a waste ink tank according to claim 6, wherein the opening communicating with the atmosphere also serves as an introduction portion for flowing ink leaking from the ink supply unit to the waste ink tank. The inkjet recording apparatus according to claim 6, wherein the inkjet recording apparatus includes a black ink or other ink containing a pigment. The inkjet recording apparatus having a waste ink tank according to claim 6, wherein a gas-liquid exchange membrane is used in an opening communicating with the atmosphere.

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