JP2008200914A - Inkjet recording apparatus and ink supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus which can perform ejection from an inkjet head without causing poor ejection from the inkjet head in the reoperation of the inkjet recording apparatus or causing wasteful ink consumption, and to provide an ink supply method. <P>SOLUTION: This inkjet recording apparatus comprises: a main tank 10 for storing ink; the inkjet head 40 for applying printing to a recording medium by ejecting the ink; an ink supply passage for carrying the ink to the inkjet head 40 from the main tank 10; a sub-tank 20 for temporarily retaining the ink which is provided in the ink supply passage; a degasifier 30 for removing gas out of the ink which is provided in the ink supply passage; and an ink-supply-passage blocking means for blocking the ink supply passage between the degasifier 30 and the ink jet head 40. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and an ink supply method that can be suitably used for an ink jet printer that ejects droplets onto a recording medium.

  As shown in FIG. 3, a conventional general inkjet recording apparatus includes an ink tank 10 that supplies ink that can be replaced or replenished to an inkjet head 40 that ejects ink droplets of a desired volume onto a recording medium. The connection is made via the ink supply path 80.

  An ink jet recording apparatus has a structure in which an ink supply tank is a housing in a recording apparatus that performs a large amount of printing in relation to printing by reciprocating an ink jet head that receives ink supply from an ink supply tank in the paper width direction of the recording paper. And a method of supplying ink to the ink-jet head via an ink supply path.

  When driving the inkjet head, it is necessary to control the pressure applied to the ejection nozzle surface of the inkjet head within a certain range in order to ensure its stable operation. In order to avoid unintentional spillage and dropouts that are not related to ink ejection from the nozzles, the pressure should be such that the negative negative pressure is below a certain level so as not to hinder ink ejection. The appropriate range is determined by the inkjet head.

  In the case of a small-capacity ink tank, this pressure control can be performed by arranging the height in the ink jet printing apparatus at a position relative to the height of the ink jet head. However, in that case, the pressure applied to the ink jet head varies depending on whether the amount of ink in the ink tank is maximum or near empty.

  When the pressure fluctuation range exceeds the appropriate range for stable driving of the ink jet head, as shown in FIG. 3, a sub tank 20 is further provided in the middle of the ink supply path connecting the ink tank and the ink jet head. Thus, a configuration is employed in which the ink is once stored in the interior and then supplied to the inkjet head.

  In such a configuration, the water level of the ink in the sub tank is measured by the ink amount monitoring sensor, and the ink is transferred from the ink tank to the sub tank before the water level drops and the pressure applied to the inkjet head falls below the lower limit of the appropriate range. The pressure applied to the ink jet head is controlled within a range that does not exceed the upper limit of the appropriate range.

    By the way, since the ink jet head pressurizes the ink in the pressure generating chamber to generate droplets, if the ink contains bubbles, the pressure of the ink decreases and the droplet discharge performance also decreases. Ink jet heads need to be supplied with ink that does not contain dissolved air. For this reason, ink that has been sufficiently deaerated at the factory is housed in a cartridge or pouch and packed in an airtight container as a product, and the ink supply path has a gas barrier property so that the deaeration effect can be maintained. A highly flexible tube is employed.

However, in an inkjet recording apparatus that prints a poster or the like using a large format recording medium, a large amount of ink is consumed during printing. Therefore, a degassing system is incorporated in the ink supply path to remove non-depleted air bubbles. The ink supply tank is configured as a tank capable of injecting ink from the outside so that even ink can be supplied, and the ink in the ink supply tank is passed through a deaeration device comprising a hollow fiber bundle that receives negative pressure from the outside. Means for supplying to the inkjet head have been proposed (for example, Patent Documents 1 and 2).
JP 11-48491 A JP 2006-239859 A

  In the ink jet recording apparatus as described above, when the apparatus is stopped, the vacuum pump that exerts a negative pressure action on the deaeration device is not normally operated in order to prevent an increase in ink viscosity. In this case, as time elapses, air is re-dissolved in the ink in the deaeration device, and further, air is re-dissolved in the ink supply path or the ink in the ink jet head. When the apparatus is operated again in this state, there is a problem in that the ink jet head has a discharge failure due to ink having no degassing effect. Further, when the apparatus is restarted, it is necessary to operate the vacuum pump to forcibly discharge the ink between the deaeration device and the ink jet head, resulting in a problem that the ink cost is increased.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides an ink jet recording apparatus and an ink supply method capable of discharging an ink jet head without causing a discharge failure of the ink jet head even when the apparatus is restarted, and without consuming unnecessary ink.

  According to a first aspect of the present invention for solving the above problems, a main tank that stores ink, an inkjet head that performs printing on a recording medium by ejecting the ink, and ink from the main tank to the inkjet head. An ink supply path for conveying; a sub-tank for temporarily holding the ink provided in the ink supply path; and a deaeration device for removing gas in the ink provided in the ink supply path; The ink jet recording apparatus includes an ink supply path blocking unit that blocks the ink supply path between the deaeration device and the inkjet head, and a transport unit that transports the recording medium.

  According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the deaeration device is installed in the ink supply path between the main tank and the sub tank. is there.

  A third aspect of the present invention is the ink jet recording apparatus according to the first aspect or the second aspect, wherein the ink supply path blocking means is a tube pump.

  According to a fourth aspect of the present invention, the ink degassing device is installed in the ink supply path between the sub tank and the inkjet head. In the inkjet recording apparatus described.

  According to a fifth aspect of the present invention, in the ink jet according to the first to fourth aspects, the ink supply path blocking means is an on-off valve provided for pressurizing the ink jet head. In the recording device.

  According to a sixth aspect of the present invention, there is provided the degassing apparatus according to any one of the first to fifth aspects, wherein the degassing apparatus is a degassing apparatus having a hollow fiber bundle that is degassed by a vacuuming means for vacuuming from outside. In the ink jet recording apparatus according to the aspect.

  According to a seventh aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to sixth aspects, further comprising control means for controlling the ink supply path blocking means and the evacuation means. .

  According to an eighth aspect of the present invention, there is provided a main tank for storing ink, an ink jet head for printing on a recording medium by discharging the ink, and an ink supply path for transporting ink from the main tank to the ink jet head. A sub tank that temporarily holds the ink provided in the ink supply path, a deaeration device for removing gas in the ink provided in the ink supply path, and the deaeration device; An ink supply method in an ink jet recording apparatus, comprising: an ink supply path blocking means for blocking the ink supply path between the ink jet heads; and a transport means for transporting the recording medium, wherein the ink jet recording apparatus is stopped. Control means for controlling the ink supply path shut-off means and the ink deaeration device when restarting , In the ink supplying method for opening the ink supply path blocking means after operating said ink deaerator.

  As described above, in the present invention, since the means for blocking the ink is installed between the deaeration device and the inkjet head, the re-dissolution of air does not reach the inkjet head when the device is stopped, and the inkjet head There is an effect that the stability can be ensured and the ejection stability of the inkjet head can be ensured with a smaller amount of ink consumption than in the past.

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

<First embodiment>
FIG. 1 is a block diagram showing a first embodiment of an ink jet recording apparatus according to the present invention.

  The ink supply device includes a main tank 10, an ink supply path 80, a sub tank 20, a deaeration device 30, an inkjet head 40, pumps 61 to 63, and the like. The ink supply path 80 is a portion surrounded by an alternate long and short dash line in FIG.

  The main tank 10 is a container in which ink is stored, and the material is not particularly limited, such as metal such as stainless steel or resin.

  The ink supply path 80 is a first ink supply path 81 that is a supply path that transports ink from the main tank 10 to the sub tank 20, and a second ink supply path 82 that is a supply path that transports ink from the sub tank 20 to the inkjet head 40. have. The first ink supply path 81 and the second ink supply path 82 are portions surrounded by dotted lines in the drawing. In the ink supply path 80, the side closer to the main tank 10 is the upstream side, and the side closer to the inkjet head 40 is the downstream side.

  The first ink supply path 81 is provided with a deaeration device 30 and a first ink supply path pump 61 from the upstream side between the main tank 10 and the sub tank 20. In the second ink supply path 82, the second ink supply path pump 62 and the ink supply path arranged in parallel with the second ink supply pump 62 are blocked between the sub tank 20 and the inkjet head 40. An on-off valve 55 as means is installed. Further, the second ink supply pump 62 is branched and arranged so that ink passes through the second ink supply path pump 62 side when the on-off valve 55 is closed. Since the on-off valve 55 is a means for blocking the ink supply path, a stopper, a shutter, or the like can be used instead.

  Further, a control board 70 capable of controlling the operations of the first ink supply path pump 61 and the vacuum pump 65 is installed.

  The sub tank 20 includes a bag-like pack and holds the deaerated ink. The sub tank 20 also includes an ink amount holding device 21 having a mechanism for controlling the ink in the sub tank 20 so as to keep a constant amount. When the ink in the sub tank 20 decreases, the first ink supply path pump 61 pumps up ink from the main tank 10.

  FIG. 4 is a cross-sectional view of an example of a deaeration device. As shown in FIG. 4, the deaeration device 30 includes a hollow fiber yarn 90, a rubber O-ring 91, an exhaust port 92, and a vacuum pump 65. Ink flows from the inlet-side channel 95 to the outlet-side channel 96 in the direction indicated by the arrows in the figure. Then, the ink is passed through the hollow fiber fiber 90 having gas permeability, and vacuum is drawn from the exhaust port 92 by the vacuum pump 65 to remove gas such as air dissolved in the ink. In FIG. 4, the ink is passed from one end side to the other end side of the hollow fiber yarn 90 of the deaeration device 30, but the configuration of the present invention is not limited to this. The vacuum layer 93 and the ink layer 94 are partitioned by an O-ring 91. The O-ring 91 is fixed by the support 97 so that ink and gas do not leak from the vacuum layer 93 and the ink layer 94. Normally, the degassing device 30 is evacuated by the vacuum pump 65 regardless of whether the inkjet head 40 is being discharged or filled, but when the device is stopped, the vacuum pump 65 is also stopped, and the degassing device 30 is in an open air state. It is.

  The inkjet head 40 is an inkjet printer head that performs printing by discharging ink onto a recording medium. The ink jet printer here includes printers used in the patterning field, industrial ink jet printers for mass printing, color filters, organic EL patterning, and the like. The filling method of the inkjet head 40 will be described in detail later.

  The first ink supply path pump 61, the second ink supply path pump 62, and the suction pump 63 are pumps. In this embodiment, the first ink supply path pump 61, the second ink supply path pump 62, and the suction pump 63 are tube pumps that transport ink by squeezing the tube. The supply path 80 is shut off.

  Next, the ink flow and filling method will be described. When ink is ejected by the ink jet head 40, the ink is ejected from the ink jet head 40 by opening the on-off valve 55 of the second ink supply path 82. When the ink jet head 40 is filled with ink or cleaned, the on-off valve 55 of the second ink supply path 82 is closed and the second ink supply path pump 62 is operated by pressure, and suction is performed via the suction cap 75. There is a method in which the pump 63 is operated to perform suction. At this time, when the capacity of the sub tank 20 decreases due to ink ejection or filling, the first ink supply path pump 61 is operated by the ink amount holding device 21 to supply ink from the main tank 10 to the sub tank 20, and the sub tank 20 is always kept at a constant ink level. Keep quantity.

  In the case of the above-described discharge filling, the ink jet recording apparatus is in operation, and the deaeration device 30 is evacuated by the vacuum pump 65, so that the air dissolved in the ink is removed, and the deaeration effect is obtained. Is filled in the inkjet head 40. When the ink jet recording apparatus is stopped, the vacuum pump 65 is also stopped, so that the air in the deaeration device 30 is dissolved again over time. However, since the first ink supply path pump 61, which is a tubing pump, is installed between the deaeration device 30 and the inkjet head 40 to block the ink supply path 81, the ink in which the air is re-dissolved by the deaeration device 30 The ink that is blocked by the first ink supply path pump 61 and reaches the inkjet head 40 does not lose its deaeration effect. For this reason, even when the inkjet recording apparatus is restarted, the inkjet head 40 can be discharged well.

  Further, when the ink jet recording apparatus is restarted, the ink pump 40 is discharged or filled after the vacuum pump 65 is operated by the control substrate 70, whereby the ink amount holding device 21 of the sub tank 20 is operated, and the first ink supply path Through the pump 61, the ink that has been degassed by the deaeration device 30 can flow to the downstream inkjet head 40.

  By this method, since the ink having a deaeration effect can be filled into the ink-jet head 40 even when the ink-jet recording apparatus is restarted, the ejection stability of the ink-jet head 40 is ensured, and a smaller amount of ink is consumed than before. Therefore, the ejection stability of the inkjet head 40 can be ensured.

<Second Embodiment>
FIG. 2 is a block diagram showing a second embodiment of the ink supply apparatus according to the present invention.
In addition, about the thing which performs the same function as 1st embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted suitably.

  The ink jet recording apparatus of the second embodiment is different from the first embodiment in that the first ink supply path 81 includes only the first ink supply path pump 61 and the second ink supply path 82. The deaerator 30 between the sub tank 20 and the inkjet head 40, the second ink supply path pump 62, and an open / close function as a means for blocking the ink supply path arranged in parallel with the second ink supply pump 62 The second ink supply pump 62 is branched and arranged so that the ink passes through the second ink supply path pump 62 side when the on-off valve 55 is closed.

  In this configuration, when the ink jet recording apparatus is stopped, the ink supply path 82 is shut off by closing the second ink supply path pump 62 and the on-off valve 55. Further, as in the first embodiment, when the ink jet recording apparatus is restarted, after the vacuum pump 65 is operated by the control substrate 70, when the ink jet head 40 is discharged and when filling is performed by suction, the on-off valve 55 is opened, and the ink deaerated by the deaerator 30 flows to the downstream inkjet head 40. Further, when pressurizing and filling the inkjet head 40, the second ink supply path pump 62 is operated while the open valve 55 is closed, and pressurization is performed. At this time, the ink amount holding device 21 of the sub tank 20 is activated, and the ink that has been deaerated by the deaeration device 30 can flow to the downstream inkjet head 40 through the second ink supply path pump 62. .

  In such a second embodiment, since the deaeration device 30 is disposed in the vicinity of the inkjet head 40, the ink having a more deaeration effect is filled in the inkjet head 40, and thus the ejection stability. There is an additional advantage.

  FIG. 5 is a schematic perspective view of the ink jet recording apparatus.

  The ink jet recording apparatus 1 of the present embodiment is an ink jet recording apparatus that scans ink jet head portions 40a, 40b, 40c, and 40d provided for each color. The ink jet recording apparatus 1 includes a carriage 7 on which ink jet head portions 40a, 40b, 40c, and 40d are mounted, an ink supply pipe 6 that is a flexible tube, and ink jet head portions 40a, 40b, and 40c via the ink supply pipe 6. , 40d are also provided with main ink tanks 10a, 10b, 10c, 10d for supplying ink. The ink supply pipe 6 is also a part of the ink supply path.

  The carriage 7 is mounted on the pair of guide rails 3a and 3b so as to be movable in the axial direction. Hereinafter, this axial movement is referred to as a main scanning direction. A drive motor 4 is provided on one end side of the guide rails 3a and 3b. The timing belt 5 is moved by the driving force of the drive motor 4, and the carriage 7 connected to the timing belt 5 is further moved. In order to grasp the movement position with high accuracy, the carriage 7 is provided with, for example, an optical linear encoder (not shown).

  Further, a pair of transport rollers 2a and 2b are provided along the guide rails 3a and 3b on both ends in the direction orthogonal to the transport direction of the carriage 7, respectively. These transport rollers 2 a and 2 b transport the recording medium S in a direction orthogonal to the transport direction of the carriage 7. Hereinafter, the direction in which the recording medium S is conveyed is referred to as the sub-scanning direction.

  Then, while the recording medium S is fed by these transport rollers 2a and 2b, the carriage 7 is scanned in a direction orthogonal to the feeding direction, whereby ink is applied onto the recording medium S by the ink jet head portions 40a, 40b, 40c and 40d. A character, an image, etc. are recorded by discharging.

  Note that the inkjet head portions 40a, 40b, 40c, and 40d of the present embodiment eject single color inks, and are black (B), yellow (Y), magenta (M), and cyan (C), respectively. Four are arranged side by side corresponding to the color and are mounted on the carriage 7. In addition, a deaeration device, an inkjet head, and a part of an ink supply path are mounted on the inkjet head unit.

  Further, four main ink tanks 10a, 10b, 10c, and 10d are provided for each color corresponding to the respective ink jet head portions 40a, 40b, 40c, and 40d. Such main ink tanks 10a, 10b, 10c, and 10d are preferably at positions that do not interfere with the movement of the carriage 7 in the main scanning direction and the movement of the recording medium S, and the inkjet head portions 40a, 40b, and 40c. , 40d is provided at a position lower by a predetermined amount than the nozzle openings for ejecting the ink of the ink jet head portions 40a, 40b, 40c, 40d so as to apply a negative pressure in the nozzles 40d.

  By such an ink jet recording apparatus 1, the recording medium S is moved in the sub-scanning direction, and the ink jet head portions 40a, 40b, 40c, and 40d are moved in the main scanning direction, thereby printing on the entire surface of the recording medium S. be able to.

  As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to such a structure.

1 is a block diagram illustrating a first embodiment of an ink supply device according to the present invention. It is a block diagram showing 2nd embodiment of the ink supply apparatus by this invention. It is a block diagram of the conventional ink supply apparatus. It is sectional drawing of an example of a deaeration apparatus. It is a schematic perspective view of an inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main tank 20 Sub tank 30 Deaeration device 40 Inkjet head 55 On-off valve 61 First ink supply path pump 62 Second ink supply path pump 63 Suction pump 65 Vacuum pump 70 Control board 75 Suction cap 80 Ink supply path 81 First ink supply Path 82 second ink supply path 90 hollow fiber yarn 91 O-ring 92 exhaust port 93 vacuum layer 94 ink layer

Claims (8)

A main tank for storing ink;
An ink jet head for printing on a recording medium by discharging the ink;
An ink supply path for transporting ink from the main tank to the inkjet head;
A sub-tank that temporarily holds the ink provided in the ink supply path;
A deaeration device for removing gas in the ink provided in the ink supply path;
An ink supply path blocking means for blocking the ink supply path between the deaeration device and the inkjet head;
An ink jet recording apparatus comprising transport means for transporting the recording medium.   The inkjet recording apparatus according to claim 1, wherein the deaeration device is installed in the ink supply path between the main tank and the sub tank.   The inkjet recording apparatus according to claim 1, wherein the ink supply path blocking means is a tube pump.   4. The ink jet recording according to claim 1, wherein the ink deaeration device is installed in the ink supply path between the sub tank and the ink jet head. 5. apparatus.   5. The ink jet recording apparatus according to claim 1, wherein the ink supply path blocking unit is an on-off valve provided to pressurize the ink jet head.   The inkjet recording according to any one of claims 1 to 5, wherein the degassing device is a degassing device having a hollow fiber bundle that is degassed by a vacuuming means for vacuuming from outside. apparatus.   The ink jet recording apparatus according to claim 1, further comprising a control unit that controls the ink supply path blocking unit and the evacuation unit. A main tank for containing ink; an ink jet head for printing on a recording medium by discharging the ink; an ink supply path for transporting ink from the main tank to the ink jet head; and an ink supply path provided in the ink supply path A sub-tank for temporarily holding the ink, a deaeration device for removing gas in the ink provided in the ink supply path, and the ink supply between the deaeration device and the inkjet head An ink supply method in an ink jet recording apparatus, comprising: an ink supply path blocking means for blocking a path; and a transport means for transporting the recording medium.
When the ink jet recording apparatus is stopped and then restarted, the control means for controlling the ink supply path blocking means and the ink degassing apparatus operates the ink supply path blocking means after operating the ink degassing apparatus. An ink supply method characterized by opening.

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