JP4813873B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink deaeration device of an ink jet recording apparatus that records an image on a recording medium by ejecting ink droplets from an ink jet head.

A normal inkjet recording apparatus records an image by reciprocating an inkjet head that receives ink supply from an ink supply tank via a tube in the recording medium width direction of the recording medium. By the way, the ink jet recording apparatus pressurizes the ink in the pressure generating chamber in the ink jet head to discharge the ink droplets. Therefore, if the ink contains bubbles, the pressure of the ink is lowered, and the ink droplet discharge performance is also improved. descend. For this reason, an ink cartridge in which an air shielding bag is filled with ink sufficiently deaerated at a factory so that the ink serving as an ink supply tank does not contain dissolved air is provided and used. However, an ink jet recording apparatus that records an image on a large recording medium consumes a large amount of ink during recording. For this reason, in the ink cartridge described above, the replacement work becomes complicated and the working efficiency is lowered, so a deaeration device is provided in the ink supply path between the ink jet head and the ink supply tank. The deaeration device includes a deaeration module, a negative pressure (vacuum) line 1, and a vacuum pump. When the vacuum pump is operated, air is removed from the ink through the negative pressure (vacuum) line, and the air is removed from the ink on the surface of the ink in contact with the vacuum part. An ink jet recording apparatus using such a deaeration device has been proposed. (For example, refer to Patent Documents 1 and 2). In addition, a plurality of gas permeable hollow fibers as shown here are bundled in a degassing module, and the ink is passed through the hollow fibers to draw negative pressure (vacuum) from the outside of the hollow fibers. A specific example using a method (hollow fiber bundle filter) for removing gas trapped in the water has been proposed. (For example, refer to Patent Documents 3 and 4). On the other hand, an apparatus in which a deaeration apparatus configured by such a deaeration method is incorporated in an ink jet recording apparatus has been proposed. (For example, see Patent Documents 5 and 6)
JP 2004-174793 A JP 2004-17517 A Japanese Patent Laid-Open No. 11-209670 Japanese Patent Laid-Open No. 5-17712 JP 11-48491 A JP 11-48493 A

  In recent years, an inkjet recording apparatus has a higher recording speed due to an improvement in the performance of an inkjet head, etc., and a degassing capacity increases with an increase in the amount of ink supplied. The inkjet recording apparatus includes a hollow fiber bundle when the above deaeration apparatus is used. The shape of the deaeration module becomes larger and when a deaeration device is used, it is deaerated by a vacuum pump, so a deaeration device is required for each ink color used in the ink jet recording device, and a negative pressure (vacuum) line As the number increases, it becomes complicated and the installation place in the apparatus is restricted. However, an ink jet recording apparatus that reciprocates the ink jet head in the recording medium width direction of the recording medium is connected from an ink supply tank via a tube. At present, none of the tubes have the inherent flexibility and gas permeability of the tube, and the ink degassed through the degassing device stays in the tube, so that the ink degassing rate decreases with time. End up. Therefore, in consideration of when the ink jet recording apparatus is stopped, it is necessary to shorten the distance between the ink jet head and the deaeration device in order to eliminate wasted ink as much as possible. However, the conventional degassing apparatus has a drawback that the ink jet head and the degassing apparatus cannot be arranged short because of the above arrangement and installation restrictions. Therefore, the present invention has improved such disadvantages, further improved the configuration of the deaeration device and the arrangement efficiency of the deaeration module, and uses the deaeration device that can be improved in size, weight and installation. An object of the present invention is to provide an ink jet recording apparatus.

  In order to achieve the above object, an inkjet recording apparatus of the present invention includes an inkjet head that ejects ink onto a recording medium, an ink supply tank that supplies ink to the inkjet head, an ink supply path that connects the inkjet head and the ink supply tank, and And a deaeration device that is provided in the ink supply path and includes two or more deaeration means made of a hollow fiber bundle subjected to a negative pressure action and an entire airtight space containing the deaeration means.

  The operation of the above problem solving means is as follows. Since the airtight space is shared by a plurality of deaeration means, the apparatus can be reduced in size. Further, the surface area of the deaeration means is increased compared to the case where one deaeration means is arranged in the airtight space, and the deaeration can be performed efficiently. Further, even when different colors of ink are supplied for each deaeration means, the plurality of colors of ink can be degassed simultaneously by pulling the entire hermetic space under a negative pressure.

  As described above, the deaeration device of the present invention forms the same space as the space where negative pressure (vacuum) is drawn from the outside of each hollow fiber bundle corresponding to the inks of a plurality of ink colors mounted on the inkjet recording apparatus This makes it possible to install the deaeration device in the vicinity of the ink jet head mounted on the carriage by reducing the negative pressure (vacuum) line in a compact and lightweight manner, thereby improving the installation property. Can be realized.

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

  FIG. 1 is a configuration diagram schematically showing a basic configuration relating to ink supply of the ink jet recording apparatus of the present invention. In FIG. 1, ink is supplied from an ink supply tank 1 to a sub tank 3 having a function of controlling to a constant water head value of an inkjet head 6 by a pump 2 via an ink supply tube 2a. The ink supplied to the sub tank 3 is sent to a deaeration device 5 disposed in a carriage 4 that can reciprocate via an ink supply tube 3a, and predetermined air is degassed from the inflow ink by the deaeration device 5. Ink is supplied to the inkjet head 6 via the ink supply tube 6a. The ink supply system is provided for each ink color / type mounted on the ink jet recording apparatus, and the schematic diagram typically shows a configuration of one color (type).

  Recording with an ink jet recording apparatus having the above ink supply system will be described. The carriage 4 is mounted with an inkjet head 6 and is supported by a guide member (not shown) so as to be able to reciprocate in a main scanning direction perpendicular to the conveyance direction of the recording medium on a recording medium (not shown) disposed below the inkjet head 6. Yes. Further, a service station for cleaning the inkjet head 6 and the like is provided outside the non-printing area in the main scanning direction, and a capping portion 7 for sealing the nozzle formation surface of the inkjet head 6 is disposed in this service station. Has been. A negative pressure can be applied to the capping unit 7 by a suction pump 8, and an air release valve 9 is also provided so that the negative pressure state of the capping unit 7 can be opened. With this configuration, it is possible to remove dust accumulated in the inkjet head 6 (cleaning operation) and perform an initial ink filling operation into the apparatus. In the above-described apparatus configuration, when ink supply to the ink jet head 6 and ink discharge preparation are completed, a print signal from the external host is transmitted to the carriage 4 drive system and ink jet head 6 (not shown) via the control board (not shown), and the print signal is generated. Correspondingly, ink droplets are ejected onto the recording medium to form an image.

  2 to 8 illustrate the deaeration device of the present invention disposed on the ink supply system of the ink jet recording apparatus, and FIG. 2 is an overview perspective view according to the embodiment of the deaeration device of the present invention. It is. FIG. 3 is a view showing a cross-section of the main part taken from the AA direction of FIG. 2 of the embodiment of the present invention. FIG. 4 is a view showing a cross-section of the main part taken from the BB direction of FIG. 2 of the embodiment of the present invention.

  FIG. 5 is an overview perspective view according to an embodiment of a deaeration device of another embodiment. FIG. 6 is a view showing a cross-section of the main part taken as a cross-section from the CC direction of FIG. 5 in another embodiment. FIG. 7 is a view showing a cross-section of the main part taken as a cross-section from the FF direction of another embodiment of FIG. FIG. 8 is a schematic perspective view of a deaeration module including a hollow fiber bundle filter loaded in the deaeration device of the present invention.

  The deaeration device 5 shown in FIGS. 2 and 5 is arranged on the carriage 4 in the vicinity of the ink jet head 6 in order to ensure sufficient deaeration ink characteristics in the present invention. Otherwise, it may be arranged on the ink supply system downstream of the ink supply tank 1 on the ink jet recording apparatus. 2 and 5, the deaeration device 5 is a predetermined configuration of the deaeration modules 50a, 51a, 52a and the deaeration modules 50a, 51a, 52a, which are deaeration means constituted by a hollow fiber bundle filter as a unit configuration. The vacuum pump 10 pulls a negative pressure (vacuum) in the outer layer, and the negative pressure (vacuum) line 10a connecting the vacuum pump 10 and the deaeration modules 50a, 51a, 52a. The deaeration module 50a in FIG. 8 bundles a fiber having gas permeability in the ink supply direction (E) with a hollow fiber having a through hole that communicates at one end with the other end. Bundled with plastic material, modularized. The both end portions 50c do not have an opening, and cannot contact the outside air, so that the hollow fiber bundle is firmly held at the upper and lower ends. The intermediate portion 50d is provided with a partial opening so as to hold the hollow fiber bundle and allow contact with the outside air. The deaeration method of the present deaeration module 50a is such that when the ink flows through the hollow fiber bundle in the ink supply direction (E), the intermediate part 50d that can come into contact with the outside air is made negative pressure (vacuum). The gas (air) dissolved in is removed and deaerated. Next, description will be made on an embodiment in which the deaeration module 50a and the deaeration modules 50b, 51a and 52a having the same configuration are formed as the deaeration device 5.

  2 to 4 and 8, the ink stored in the sub tank 3 is guided to the deaeration device 5 through ink supply tubes 3a, 3b and 3c which are ink supply paths. The deaeration device 5 has a bamboo-shaped connecting portion that can press-fit and connect the ink supply tubes 3a, 3b, and 3c as an inlet, and the connecting portion that is connected to the ink tubes 6a, 6b, and 6c as an outlet is airtight. Installed. In the present embodiment, the three ink supply paths can be connected to one deaeration device 5, but the number of connection paths is not limited in design. The deaeration device 5 is made of an ink-resistant plastic material and can be attached and detached separately from the upper and lower bodies as shown in FIGS. 3 and 4, and the ink joint resistance is ensured at the cover joint of the upper and lower bodies. A rubber seal member 21 having the above is installed and configured. By fixing the upper and lower covers with a fixing member (not shown), the space in the upper and lower covers of the deaeration device 5 is kept airtight.

  Deaeration modules 50a, 51a, 52a are disposed in the airtight space at predetermined positions in the through hole / vertical direction of the hollow fiber bundle. In the upper and lower end portions 50c, 51c, 52c of each deaeration module 50a, 51a, 52a, a rubber seal member 22 having ink resistance for holding a predetermined airtight space in each of the upper and lower covers of the deaeration device 5 is provided. Is installed, and an airtight space closed by the upper and lower covers of the deaeration device 5 is formed in the upper and lower ink supply paths through the respective deaeration modules for each deaeration module. When the ink flows, the airtight space becomes a pressure loss due to the expansion / reduction of the streamline at the inflow / discharge of the ink. Therefore, in this embodiment, the airtight space has a predetermined space shape based on the experimental result. With the above configuration, each of the deaeration modules disposed in each ink supply path is kept airtight in the direction of the through hole of the hollow fiber bundle in each ink supply path. The intermediate portions 50d, 51d, 52d of the deaeration modules 50a, 51a, 52a and the spaces in the upper and lower covers of the deaeration device 5 form airtight spaces 50e, 51e, 52e, respectively. These airtight spaces 50e, 51e, 52e are communicated by a common airtight space 5f to form one whole airtight space 5g. Here, the common airtight space 5f is provided near the upper end of the space in the deaeration module 5. Here, the entire airtight space 5g is the same common space in the gas phase, but is different in the liquid phase. That is, the airtight spaces 50e, 51e, and 52e constitute an isolation space partitioned by a wall for each of the deaeration modules 50a, 51a, and 52a. A connection portion having a bamboo stalk shape connected to a discharge opening / closing valve (not shown) in the vicinity of the lower end portions 50c, 51c, 52c of the deaeration modules 50a, 51a, 52a of the isolated airtight spaces 50e, 51e, 52e ( An arrow D) is installed in an airtight manner, and a connection portion (arrow S2) having a bamboo shoot shape that is tube-connected to a liquid level sensor (not shown) is installed in an airtight manner at an upper portion separated by a predetermined distance. In this example, a commercially available non-contact pressure sensor is used as the liquid level sensor to detect the presence or absence of liquid.

  Further, a connecting portion having a bamboo shoot shape that can be press-fitted and connected is hermetically installed in a part of the lower cover portion of the deaeration device 5 in the gas-phase common hermetic space 5f. Airtight space lines up to are formed. In the present embodiment, a commercially available tube pump system is selected as the vacuum pump 10 from the viewpoint of miniaturization and weight reduction, but the pump system is not limited as long as negative pressure (vacuum) can be efficiently applied.

  In the above configuration, when the vacuum pump 10 is operated and the entire hermetic space 5g is in a predetermined negative pressure (vacuum) environment, an ink inflow operation to the ink jet head 6 is started, and the deaerator 5 inlets 3a, 3b, 3c are started. The ink that has flowed in flows into the hollow fiber bundle in the direction of arrow E through the cross-sections 50b, 51b, 52b of the degassing modules 50a, 51a, 52a and flows to the discharge ports 6a, 6b, 6c at the top of the degassing device 5. The ink that has flowed in is subjected to negative pressure (vacuum) acting on the intermediate portions 50d, 51d, 52d of the deaeration modules 50a, 51a, 52a, and the dissolved air is separated. Released to the atmosphere. In the present embodiment, in order to efficiently remove the air initially staying in the deaeration modules 50a, 51a, 52a at the time of initial ink filling, the ink flows in and out in the direction of arrow E (vertical direction). The direction was bottom-in / up. Now, when the vacuum pump 10 discharges to the atmosphere, a small amount of deaeration ink is discharged together with the exhaust air on the performance of the deaeration modules 50a, 51a, 52a. From 52d, it oozes out into the entire airtight space 5g.

  The deaeration ink that oozes out covers the surface of the degassing modules 50a, 51a, 52a intermediate portions 50d, 51d, 52d that come into contact with the negative pressure (vacuum), thereby causing a decrease in the deaeration efficiency and the stain. The discharged deaerated ink has the characteristics of inflow ink, and if the color type or the like is different, color mixing (mixing) occurs at the bottom of the whole airtight space 5g, causing functional problems in the ink supplied to the inkjet head 6. It will be. In the present embodiment, in order to avoid the functional failure, in the whole gas-tight space g common in the gas phase, the air-tight space 50e isolated in a liquid layer at the lower part of each degassing module 50a, 51a, 52a, By forming 51e and 52e, a color mixing (mixing) does not occur in a predetermined amount of deaerated ink that oozes out and accumulates at the bottom.

  In the present embodiment, inks of different colors are supplied to the deaeration modules 50a, 51a, and 52a, but it is also possible to supply inks of the same color.

  Further, in each of the airtight spaces 50e, 51e, 52e, a liquid level sensor for detecting the liquid level of the deaerating ink that oozes out is provided on the connecting portion (arrows S1 to S3). When the sensor detects the deaerated ink that oozes out, the on-off valve connected to the connecting portion (arrow D) is operated to allow the bleed out ink to be discharged before reaching the common airtight space 5f. . In the present embodiment, the discharge pipe flow path is integrated into one path, and one on-off valve is provided at the location where the flow paths are concentrated, and the manual operation is performed. However, this is automatically performed by utilizing a commercially available solenoid valve or the like. Is possible. By performing a conservative operation in this manner, the functional failure can be avoided. In this embodiment, the vacuum pump 10 is set to a negative pressure (vacuum) of 0.1 atm or less so that 50 ml of ink per minute is obtained. When flowing, the air in the ink was degassed to 20% or less of the saturated state, and could be maintained.

  Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, as shown in FIGS. 5 to 7, constituent members and operations constituting the deaeration modules 50 a, 51 a, 52 a are basically the same. The aim in the present embodiment is to make the best use of the advantages of the member configuration of the deaeration modules 50a, 51a, 52a, and to make the connection part (arrows S1 to S3) and the connection part (arrow D) in the embodiment more useful. This simplifies and further improves the effects of the present invention. In the present embodiment, the airtight spaces 50e, 51e, 52e are not provided for each of the deaeration modules 50a, 51a, 52a, and all the deaeration modules 50a, 51a, 52a are accommodated in one whole airtight space 5g. Yes.

  Since the lower end portion 50c of the deaeration module 50a is formed of a plastic material and is hermetically installed with the lower case of the deaeration device 5, the hollow fiber which is the main configuration of the deaeration module 50a is used. Both bundles are airtightly isolated. In other words, even if the ink that oozes out by deaeration collects at the bottom of the entire airtight space 5g, it does not reach the lowermost opening of the intermediate parts 50d, 51d, 52d of the deaeration modules 50a, 51a, 52a. There is no color mixing. The airtightly isolated space has the same function as the airtight spaces 50e, 51e, and 5e isolated in a liquid phase in the embodiment. Therefore, the connection part (arrow S1) and the connection part (arrow D) in the above embodiment are provided in an airtight space formed by the lower end part 5c of the deaeration module 5a and the lower case of the deaeration device 5, and the connection part (arrow D) is provided on each connection part. By providing a liquid level sensor and a discharge opening / closing valve (not shown), the structural members can be further simplified from the above embodiment.

    As described above, ink droplets can be stably ejected by installing the deaeration device 5 on the carriage 4 which is small, light and easy to install and can stably maintain the ink deaeration efficiency. Therefore, it is possible to realize a highly stable ink jet recording apparatus.

1 is a configuration diagram schematically showing a basic configuration relating to ink supply of an ink jet recording apparatus of the present invention. Overview perspective view according to an embodiment of the deaeration device of the present invention Sectional drawing of the principal part made into the cross section from the AA direction of FIG. 2 which is embodiment of this invention Sectional drawing of the principal part made into the cross section from the BB direction of FIG. 2 which is embodiment of this invention Overview perspective view according to another embodiment of the escapement apparatus of the present invention Sectional drawing of the principal part made into the cross section from CC direction of FIG. 5 which is embodiment of this invention Sectional drawing of the principal part made into the cross section from the FF direction of FIG. 5 which is embodiment of this invention Overview perspective view of a deaeration module comprising a hollow fiber bundle filter loaded in the deaeration device of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ink supply tank 3 Sub tank 3a Ink supply tube 4 Carriage 5 Deaeration apparatus 50a Deaeration module (deaeration means)
50c Deaeration module both ends 50d Deaeration module middle part 50e Airtight space 5f Common airtight space 5g Whole airtight space 6 Inkjet head 6a Ink supply tube 10 Vacuum pump 10a Negative pressure (vacuum) line

Claims (7)

An inkjet head that ejects ink onto a recording medium;
An ink supply tank for supplying ink to the inkjet head;
An ink jet recording apparatus comprising: an ink supply path connecting the ink jet head and the ink supply tank;
Two or more deaeration means comprising a bundle of hollow fibers which are provided in the ink supply path and receive an action of negative pressure, and an overall airtight space containing the deaeration means;
A suction port communicating with a pump for sucking air in the entire hermetic space;
A dividing unit that divides the lower side of the whole hermetic space in the vertical direction for each deaeration unit;
Ink detection means for detecting the presence or absence of ink leaked from the deaeration means;
An ink discharging means for discharging the leaked ink to the outside of the entire hermetic space, and a deaeration device,
The ink jet recording apparatus, wherein the ink detection unit and the ink discharge unit are located on a lower side in a vertical direction than an uppermost portion in a vertical direction of the dividing unit.   2. The ink jet recording apparatus according to claim 1, wherein the suction port is positioned vertically above the uppermost vertical direction of the dividing unit.   The inkjet recording apparatus according to claim 1, wherein the dividing unit is a wall member that protrudes upward in the vertical direction from the bottom of the entire hermetic space between the deaeration units.   The dividing means holds the hollow fiber bundle around the hollow fiber bundle and has a plurality of openings communicating with the entire hermetic space, and is the lowest in the vertical direction of the plurality of openings. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is a lower end portion of an intermediate member positioned on a lower side in a vertical direction with respect to an opening portion positioned in the position.   5. The ink jet recording apparatus according to claim 1, wherein the ink discharge unit is positioned at substantially the same height or less in the vertical direction as the ink detection unit.   6. The ink jet recording apparatus according to claim 1, wherein the ink discharging unit is located at a lowermost part in the vertical direction of the entire hermetic space.   The inkjet recording apparatus according to claim 1, wherein the number of each of the ink detection unit and the ink discharge unit is equal to or less than the number of the deaeration units.

Images