JP2009101575A - Ink filling method of inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink filling method of an inkjet recording head which does not cause a residual of a waste ink without the need of spare discharge and wiping, and also without the need of even an ink suction capability. <P>SOLUTION: An ink liquid level in an ink storage part is set to a position higher than a discharge port of the recording head with respect to the vertical direction, and in a range that a meniscus holding force of the ink of the discharge port is not exceeded to prevent the ink from flowing out to the outside of the discharge port. The ink is filled from the ink storage part into the recording head by utilizing both a head difference and a capillary force of an ink passage that includes a pipe and an ink channel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink filling method for an ink jet recording head that fills the recording head with ink when the ink ejection state of the ink jet recording head is inspected, and does not generate bubbles in the ejection port or the ink flow path of the ink jet recording head. The present invention relates to an ink filling method for an ink jet recording head in which ink does not adhere to an exit surface.

  An ink jet recording head (hereinafter also simply referred to as a recording head) mounted on an ink jet recording apparatus performs a print inspection before shipment. In the print inspection process, ink (the same kind of ink used for printing) is filled in the ink flow path of the recording head. Ink filling is performed in a recording apparatus via a so-called cap member, in which an ink storage unit and a recording head are connected by a pipe, and a discharge port surface of the recording head is covered with a cap member and sucked by a pump. The same operation as the body recovery operation was performed.

In the main body recovery operation, when the cap member is removed from the recording head, many ink droplets remain on the ejection port surface. If these ink droplets remain on the ejection port surface, the ejection direction of the ejected ink will bend, so after separating the cap, a spatula blade is pressed against the ejection port surface to scan in the ejection port array direction. The ink droplets adhering to the discharge port surface are cleaned. (For example, see Patent Document 1)
However, when a plurality of color ejection port groups are sucked by a single cap, this cleaning operation spreads ink droplets over a wide area of the ejection port surface, and some of them penetrate into the ejection port to further mix colors. May occur. Further, bubbles may be generated in the recording head by the ink filling operation. Therefore, a preliminary discharge is performed in which a certain amount of discharge operation is performed to discharge bubbles or other colors of ink that have entered the discharge port. (For example, see Patent Document 2)
A method other than the method described above is disclosed in Patent Document 3. In the ink filling described in Patent Document 3, the suction efficiency is compared with the conventional method of sealing and sucking the entire surface of the discharge port by scanning the means for sealing the predetermined discharge port in the discharge port array direction. Improve the suction time and the amount of sucked ink. However, although the suction efficiency has been improved, in addition to the suction operation, as shown in FIG. 4, an air release operation and a blade operation on the discharge port surface are required, and these mechanisms exist. Further, after the discharge port blade operation, the preliminary discharge operation described above is performed.
Japanese Patent Laid-Open No. 62-113559 JP 11-157102 A JP 2002-347260 A

  In the print inspection of the ink jet recording head, the recording head is filled with ink, a printing operation is performed with the recording head filled with ink, and the printed matter is visually inspected to determine whether the recording head is good or bad.

  The ink filling method in the inspection process uses the same operation method as the main body recovery operation as described above. Here, the operation of supplying ink in the printing inspection process differs from the operation performed in the recording apparatus main body in the form of supplying ink. Therefore, the conditions of the suction pressure by the pump are different. In the operation performed in the main body of the recording apparatus, since the ink is filled from the ink tank, the suction pressure is small and the generation of bubbles is suppressed.

  However, when an ink tank is used in the operation in the print inspection process, the number of replacements increases. Therefore, a jig for supplying ink instead of the ink tank (hereinafter referred to as a filling nozzle) is used instead of the ink tank. Attached to. At this time, the filling nozzle attached to the recording head is provided with a pipe to the ink storage unit, and the ink must be sucked from the ink storage location to the ejection port surface of the recording head. In order to suck ink from the discharge port surface, ink cannot be filled up to the discharge port surface unless the suction pressure is higher than the suction pressure performed in the recording apparatus main body. When the suction pressure is high, the ink flow rate is increased. When the ink flow rate is increased, bubbles are likely to be generated when passing through the filter or in the shape of the flow path. When the generated foam enters the discharge port, non-discharge occurs due to the inclusion of the foam. The printed matter printed by the recording head including such bubbles is not judged as a good product, and as a result, the recording head is judged as a defective product. That is, although it is a good recording head, it may be judged as a defective product due to the presence of bubbles, which may lead to a decrease in the manufacturing yield of the recording head.

  Under the ink suction conditions in the inspection process as described above, the cap flow rate is increased by sealing and sucking the entire ejection port array of the recording head with the cap member, bubbles are generated in the ink flow paths and ejection ports, and bubbles are generated in the ejection ports. It may cause a cause of poor initial printing. Further, since negative pressure is applied to the entire discharge port, the negative pressure applied to each discharge port is dispersed and weakened. There is a difference in flow resistance between individual discharge ports. For example, when bubbles are present in the discharge port, the flow resistance is larger than that of a normal discharge port. In this state, when the entire area of the ejection port is sucked with a uniform pressure, the ink tends to flow to the side with less flow resistance, and as a result, it becomes difficult to discharge the bubbles in the ejection port. Similarly, even when the discharge ports having different discharge port diameters are arranged in the same liquid chamber, the ink easily flows to the discharge port having a relatively small discharge resistance and a large discharge port diameter.

  Further, as shown in FIG. 7, the ink flow paths in the discharge port unit 4 are formed radially from the ink supply port 5. Therefore, the portion near the ink supply port 5 has a laminar flow of ink at the time of suction, whereas the portion far from the supply port 5 becomes a stagnation with a small amount of ink flow, and the ink suction and discharge efficiency decreases.

  In order to solve the ink droplet adhesion on the discharge port surface 7 caused by the suction operation, a wiping mechanism using the blade 20 shown in FIG. 5 is required. This blade 20 cleaning operation causes ink droplets to spread over a wide area of the discharge port surface 7, and a part of the ink enters the discharge port 8 to further promote color mixing. Further, preliminary discharge shown in FIG. 6 is necessary to solve the bubbles and color mixture in the discharge port 8. However, this discharge operation discharges more than the discharge operation in normal printing in order to exhibit the bubble and ink discharge function in a short time, and under such discharge, the mist of the discharged ink droplets is It becomes easy to adhere to the discharge port surface 7.

  In some cases, the ink may adhere to the vicinity of the ejection port 8 to significantly reduce the ink droplet landing position accuracy during the printing operation, and the ejection port 8 itself may block the mist, resulting in non-ejection. Further, since the cap suction, wiping, and preliminary discharge are performed in series, the time required for ink filling becomes longer than necessary.

  As is apparent from the above, in order to suck the bubbles in the flow path 3 and the ejection port 8 and achieve the discharge, it is necessary to suck more (useless) ink, which increases the cost due to waste of waste ink. Invite. In addition, a lot of suction time is required.

  The present invention is a further improvement on the ink filling method. It is an object of the present invention to provide an ink filling method for an ink jet recording head that does not require preliminary ejection or wiping and does not require ink suction capability, and thus does not generate waste ink.

  The present invention for achieving the above object is achieved by the following means.

That is, an ink discharge state of an ink jet recording head that includes an ejection port that ejects ink, an ink channel that guides ink to the ejection port, and a filter that is disposed at an ink introduction portion of the ink channel is inspected. In the ink filling method of the ink jet recording head, the ink is filled from the ink storing portion storing the ink used for the inspection to the recording head via a pipe connecting the ink storing portion and the filter. ,
The ink liquid level in the ink reservoir is higher than the ejection port of the recording head in the vertical direction, and does not exceed the meniscus holding force of the ink in the ejection port and does not flow out of the ejection port. The ink is filled from the ink reservoir to the recording head by utilizing the water head difference and the capillary force of the ink path including the pipe and the ink flow path.

  According to the ink filling method of the ink jet recording head according to the present invention, which is performed in the print inspection process, the ink filling speed is slowed down without unnecessarily fast ink filling, and the ink is ejected while pushing out the air in the recording head. Since the ink is filled, bubbles do not exist in the recording head, particularly in the ejection port. This eliminates the recording head that has been determined to be a printing failure due to the inclusion of bubbles, thereby reducing the number of recording heads determined to be an initial printing failure and improving the yield. Furthermore, by setting the water head difference between the ink reservoir and the recording head to such an extent that the ink meniscus formed at the ejection port is not destroyed, ink does not adhere to the face surface, and there is no occurrence of bending in the ejection direction. As a result, the number of recording heads that are judged to be defective in printing is reduced, and the blade mechanism as in the conventional method is not required, and the structure of the ink filling device is simplified.

  Ink filling is performed by the ink suction operation → blade operation → preliminary ejection operation, which has been performed in the conventional mechanism, with ink filling by the head differential and capillary force, and the blade operation → preliminary ejection operation etc. can be omitted. It is possible to greatly reduce the time required for the operation. Further, since ink is filled with a head difference and capillary force, a suction cap, a pump for sucking, a blade, a preliminary discharge receptacle, a waste ink collecting mechanism and the like are not required. As a result, it is possible to reduce the size of the apparatus by reducing the ink filling mechanism of the print inspection apparatus, to reduce the ink consumption, and to prevent the generation of waste ink.

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

  FIG. 1 is a schematic diagram illustrating an ink filling method according to an embodiment of the present invention from a state where a recording head is not filled with ink.

  As shown in FIG. 1, ink (with the same kind of ink used for recording is used in the ink flow path 3 as shown in FIG. Is called recording ink). The recording ink 9 is also filled in the gap formed by the welded portion gap and the shape of the ink flow path 3, and the recording ink 9 penetrates by the capillary force, so that the atmosphere is pushed out and filled in the recording head 1. At this time, if there is a difference in capillary force or a difference in the channel length due to the gap between the channel welds in each color, the timing of extrusion filling completion due to the water head difference is different, but the recording ink 9 is filled in all the ejection ports 8. The Further, the water head difference is a height h from the tip of the ejection port 8 to the water surface of the recording ink storage tank 10. The maximum head difference h that does not destroy the discharge port meniscus is 700 mm (7 kPa) or less, and the minimum head difference is a height h at which the pressure loss of the filter 24, the ink flow path 15, and the apparatus piping is zero. (0.2 kPa) or more is desirable. In this embodiment, the recording ink is a dye system, and the length of the pipe from the recording ink storage tank 10 to the recording head 01 filter 24 is 800 mm and the inner diameter is 2 mm. The filter 24 is a non-woven fabric filter 24 having a diameter of 4.4 mm and a thickness of 0.27 mm. The diameters of the discharge ports 08 are 16.5 μm and 10.5 μm, each having 256 arrays.

  Furthermore, the table shown in FIG. 2 is an experimental result of whether bubbles are generated in the liquid chamber when the height position of the water head difference is moved and the recording ink is filled. It was confirmed that bubbles were not generated in the liquid chamber. Further, if the water head height difference h is 20 mm, the time required for ink filling becomes as long as 1 minute or more, so it is set to 50 mm or more (within 30 seconds). As a result of the above, the preferable condition water head difference is about 50 to 200 mm. Moreover, the recording ink was made into the pigment type, and it implemented on the same conditions, and the experimental result became the same result as the dye type recording ink.

  Next, the filter 24 is changed and the recording ink is a dye system and a pigment system. The length of the pipe from the recording ink storage tank 10 to the recording head 01 filter 24 is 800 mm and the inner diameter is 7 mm. The filter 24 is a mesh filter 24 having a diameter of 8.4 mm and a thickness of 0.09 mm, and the discharge ports 8 having a diameter of 320 of 25 μm are arranged. As a result of carrying out under such conditions, the maximum water head difference h that does not destroy the discharge meniscus in both the dye system and the pigment system is 200 mm (2 kPa) or less. The minimum water head difference is desirably 10 mm (0.1 kPa) or more for the height h at which the pressure loss of the filter 24, the ink flow path 15, and the apparatus piping is zero. However, if the water head height difference h is 10 mm, the time required for ink filling becomes longer, so it is set to 50 mm or more. Moreover, the water head difference which a bubble does not generate | occur | produce in a liquid chamber is 200 mm, and a suitable condition water head difference is about 50-200 mm.

  Next, the present embodiment will be described with reference to FIGS.

  The recording head 01 not filled with the recording ink 9 is installed at a predetermined position of the ink filling mechanism device, and the filling nozzle 21 is mounted on the recording head 1 (step SP1). A flexible tube 26 is attached to the filling nozzle 21, and a container (recording ink storage tank or ink storage unit) 10 in which the recording ink 9 is stored is installed at the tip. Further, a sponge 23 or the like may be attached to the tip of the filling nozzle 21 to prevent liquid sagging. The tube 26 attached to the filling nozzle 21 has liquid contact properties, and a filter 25 for filtering the recording ink 09 and an ink supply valve 22 for supplying the recording ink 09 are installed on the filling nozzle 21.

  When the recording head 01 and the ink tank 02 are set at predetermined positions, the ink supply valve 22 is opened, and the recording ink 9 penetrates into the recording head 1 by the water head difference and the capillary force and is filled with the recording ink 9 (step SP2). . When the recording ink 9 is filled up to the ejection port 8, the flow of the recording ink 9 is stopped by the meniscus holding force of the ejection port 8. A time for filling the recording ink 9 at this time is set in a timer, and when the time is up, the ink supply valve is closed. And a filling nozzle is removed and it transfers to an inspection process.

  Thereafter, an inspection pattern is printed (step 3), and the printed matter is visually inspected (step 4).

  By using such an ink filling method, since a small amount of recording ink 9 can be filled, the amount of ink used can be greatly reduced and the amount of waste liquid can be reduced, thereby reducing the cost. Further, since no pressurization or suction mechanism is required, it can be manufactured at a low cost.

It is the schematic which shows the ink filling mechanism used for the ink filling method of this invention. It is a table | surface which shows the result of having filled the ink by changing a water head difference. It is a flowchart which shows the ink filling method. It is the schematic which shows the structure of the conventional ink filling mechanism. It is the schematic which shows the blade operation | movement in the conventional ink filling mechanism. It is the schematic which shows the preliminary discharge operation | movement in the conventional ink filling mechanism. It is the schematic which shows the ink flow at the time of the suction operation in the conventional ink filling mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording head 2 Ink tank 3 Ink supply member 5 Ink supply port 6 Common liquid chamber 7 Ejection port surface 8 Ejection port 9 Recording ink 10 Recording ink storage tank 15 Ink flow path 21 Filling nozzle

Claims (2)

When inspecting the ink ejection state of an ink jet recording head comprising an ejection port for ejecting ink, an ink channel for guiding ink to the ejection port, and a filter disposed at an ink introduction location of the ink channel, In an ink filling method for an ink jet recording head in which ink filling from an ink storing portion storing ink used for inspection to the recording head is performed via a pipe connecting the ink storing portion and the filter.
The ink liquid level in the ink reservoir is higher than the ejection port of the recording head in the vertical direction, and does not exceed the meniscus holding force of the ink in the ejection port and does not flow out of the ejection port. An ink filling method for an ink jet recording head, wherein ink is filled from an ink storage section with respect to the recording head using a water head difference and a capillary force of an ink path including the pipe and the ink flow path. .   2. The ink filling method for an ink jet recording head according to claim 1, wherein the water head difference is preferably in a range of 50 mm to 200 mm.

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