JP2006159545A - Ink jet recorder and its print function recovery mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the structure of a print function recovery mechanism by eliminating a blade mechanism required in conventional system. <P>SOLUTION: (1) A nozzle surface is scanned along a nozzle array by a cap sucking the nozzle surface locally. (2) The suction cap has a conventional blade function in the shape of the surface abutting against the nozzle. (3) Scanning speed of the suction cap is variable. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus, and in order to perform normal ink ejection from an ink jet head, bubbles and thickened ink in nozzles and ink flow paths are removed, and ink droplets and thickened ink attached to the nozzle surface are removed. The present invention relates to the structure of a removed print function recovery mechanism.

  In an ink jet recording apparatus, when it arrives at a customer, in a state where it is left for a long time in a usage form, or when an ink cartridge is replaced, the nozzles of the ink jet head and the inside of the ink flow path from the ink cartridge to the nozzles are distributed. Ink for ink or thickened ink or bubbles may be present, and thickened and dried ink and foreign matter may adhere to the nozzle surface. Under such circumstances, normal ink is not supplied to the nozzles, so that the ink is not ejected, or even if ejected, the size of the ink droplets on the paper surface and the landing position accuracy are greatly deteriorated, and the quality of the formed image may be impaired. is there.

  For this reason, in an ink jet recording apparatus, fresh ink is sucked by a cap that seals the nozzle surface and a negative pressure generating means that communicates with the cap, thereby replacing the distribution ink with the actually used ink or thickening ink and bubbles in the flow path. , Or promotes dissolution of thickened ink adhering to the nozzle surface, and then presses a spatula blade against the nozzle surface and scans in the direction of the nozzle row, so that ink drops remaining on the nozzle surface and thickened The ink is scraped and removed. Further, after that, a discharge operation (preliminary discharge) is performed in order to remove the fine bubbles remaining in the nozzle or to solve the color mixing inside the nozzle that occurs when a plurality of color nozzles are sucked with a single cap. Hereinafter, such an ink suction operation and a nozzle surface cleaning mechanism will be described.

  FIG. 2 shows the configuration of the inkjet head in the inkjet recording apparatus.

  In the drawing, the ink filled from the ink cartridge connection port 02 flows to the nozzle unit 04 through the flow path member 03 and reaches the plurality of nozzles 08 from the supply port 05 of the nozzle unit 04 through the common liquid chamber 06. When an external force such as bubbles generated by rapid heating in the nozzle 08 or driving of a piezo element is applied, the ink in the nozzle 08 is pushed out of the nozzle 08 having a small flow resistance, and becomes ink droplets as a paper surface. Land on the recording medium. Ink is newly supplied into the nozzle 08 from the common liquid chamber 06 side to prepare for the next discharge. Printing is performed by repeating this process.

  FIG. 3 shows a printing function recovery mechanism of a conventional ink jet recording apparatus.

  In FIG. 2, in the ink flow path from the ink cartridge connection port 02 to the nozzle 08, air bubbles from the ink cartridge connection port 02 and the nozzle 08, bubble accumulation due to evaporation of ink in the flow path, and ink thickening. Or, the manifestation of air dissolved in the ink occurs. In response to these phenomena, the cap 11 is brought into close contact with the nozzle surface 08 and the suction pump 13 is driven in a state in which the air release valve 12 communicating with the cap 11 is closed. By applying a negative pressure and sucking fresh ink in the ink cartridge 01 through the ink cartridge connection port 02, bubbles and thickened ink in the ink flow path are discharged.

  When the suction is completed, the atmosphere release valve 12 is opened, the inside of the cap 11 is returned to atmospheric pressure, and then the cap 11 is separated from the nozzle 08 surface. This is because it is difficult to separate the cap 11 from the surface of the nozzle 08 due to a suction cup phenomenon unless the inside of the cap 11 is at normal pressure. Even when the independent atmosphere release valve 12 is not provided, it is necessary to release the atmosphere inside the suction pump 13, for example.

  The impact at the time of opening to the atmosphere causes at least a back flow of ink in the nozzle 07 sealed in the cap 11, and depending on the nozzle, the ink meniscus breaks and air enters, or a plurality of colors can be obtained with a single cap. When the nozzle groups are sucked, color mixing occurs between the nozzle groups. In addition, ink droplets may adhere to the nozzle surface 08, which may hinder ink ejection.

  Therefore, after the cap 11 is separated, the spatula blade 20 is pressed against the nozzle surface 08 to scan in the nozzle row direction, and the ink droplets adhering to the nozzle surface 08 are scraped off. However, when a plurality of color nozzle groups are sucked with a single cap, the ink droplets are spread over a wide area of the nozzle surface 08 by this cleaning operation, and some of the ink drops enter the nozzle 07 to further mix colors. Will be promoted.

  For this reason, after that, a certain amount of ejection operation is performed to discharge the bubbles and other color inks that have entered the nozzle 07 (preliminary ejection diagram 5).

  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. Under such discharge, the mist of the discharged ink droplets is generated. It easily adheres to the nozzle surface 08, and in some cases, adheres to the vicinity of the nozzle 07, significantly reducing the ink droplet landing position accuracy during the printing operation, or mist blocking the nozzle itself, resulting in non-ejection. It is.

  As described above, the mechanism that seals and sucks the entire nozzle array with the cap requires a wiping mechanism using a blade to solve ink droplet adhesion on the nozzle surface caused by the suction operation after the suction operation. To do. Then, the ink scraped by the blade is scattered and attached in the ink jet apparatus, which may cause ink contamination of the mechanism in the vicinity of the blade, resulting in malfunction. Further, preliminary discharge is necessary to solve the bubbles and color mixing in the nozzle, and there is a concern about the influence on discharge due to ink mist adhering to the nozzle surface due to the preliminary discharge.

  In addition, since the cap suction, wiping, and preliminary discharge are performed in series, the time required for recovering the printing function becomes longer than necessary.

  In addition, since negative pressure is applied to the entire nozzle area, the negative pressure applied to each nozzle is dispersed and weakened. There is a difference in flow resistance between individual nozzles. For example, when the nozzle is blocked by foreign matter, the flow resistance is larger than that of a normal nozzle. In this state, when the entire nozzle area is sucked with a uniform pressure, it becomes easier for the ink to flow to the side where the flow resistance is smaller, and as a result, it becomes difficult to discharge the foreign matter blocking the nozzle. Similarly, in the case where nozzles having different nozzle diameters are arranged in the same liquid chamber, ink can easily flow to a nozzle having a relatively small nozzle resistance and a small nozzle diameter.

  Further, as shown in FIG. 6, since the ink flow path in the nozzle unit 04 is formed radially from the ink supply port 05, the ink flow at the time of suction is a laminar flow near the ink supply port 05. On the other hand, the portion far from the supply port 05 becomes a stagnation with less ink flow, and the ink suction and discharge efficiency is lowered.

  As is apparent from the above description, in order to achieve a predetermined ink discharge function, it is necessary to suck more (waste) ink, leading to waste of ink in the ink cartridge and an increase in load of a mechanism for receiving waste ink. . In addition, a lot of suction time is required. In order to shorten the suction time, it is conceivable to improve the suction ability. However, in the ink jet recording apparatus, there is a limit from the viewpoint of space and cost in order to improve the ability of the negative pressure generating means, and it is difficult to improve the ink suction ability.

  As means for solving these problems, there is one disclosed in JP 2002-347260 A. The printing function recovery mechanism described in the public relations improves the suction efficiency compared to the conventional method of sealing and sucking the entire nozzle surface by scanning the means for sealing a predetermined nozzle in the nozzle row direction. The suction time and the amount of sucked ink are reduced.

However, the printing function recovery mechanism disclosed in Japanese Patent Application Laid-Open No. 2002-347260 has improved suction efficiency, but requires an air release operation and a nozzle surface cleaning operation in addition to the suction operation. There is a mechanism. Further, it is considered that the preliminary discharge operation described above is necessary after the nozzle surface cleaning operation.
JP 2002-347260 PR

  The present invention is a further improvement over the printing function recovery mechanism described in Patent Document 1, and does not require preliminary ejection or wiping, and further improves ink suction capability and suction efficiency and improves ink suction. An object of the present invention is to provide a printing function recovery mechanism of an ink jet recording apparatus that suppresses consumption and enables a suction operation in a short time.

  In order to achieve the above object, a printing function recovery mechanism of the present invention includes: an ink suction in an ink flow path of an ink jet head in an ink jet recording apparatus that performs printing on a recording medium by discharging ink from a nozzle of the ink jet head; In a mechanism having a cleaning function of the nozzle surface of the head, a means for sealing a predetermined nozzle group, a negative pressure generating means for bringing the inside of the sealing means into a negative pressure state, and the sealing means abut on the nozzle surface to perform scanning movement Further, the means for sealing the nozzle group has a shape having a function of cleaning the nozzle surface by scanning with the scanning moving means.

In addition, it is characterized in that it does not require an air release mechanism / operation of the negative pressure generating means. Also, by performing cleaning of the nozzle surface at the same time as suction, it is configured not to require a preliminary ejection operation and a blade mechanism. Features.

  Further, the nozzle group of a plurality of colors can be sucked with a single suction cap without mutual color mixture.

  Further, in the scanning operation by pressing the means for sealing the nozzle group in the nozzle row direction, the suction time (suction amount) per nozzle can be changed as necessary by changing the scanning speed. Features.

  As described above, according to the printing function recovery mechanism of the present invention, the suction efficiency is improved by scanning the suction cap that locally sucks the nozzle surface along the nozzle row, and the suction cap is improved. Since the shape of the nozzle contact surface has a blade function as in the conventional mechanism, ink suction and nozzle surface ink drop removal can be achieved simultaneously. This eliminates the need for the blade mechanism as in the conventional method, and has the effect of simplifying the structure of the printing function recovery mechanism.

  Further, the continuous operation of the ink suction operation → blade operation → preliminary ejection operation, which is in the conventional mechanism, becomes only the suction cap scanning operation, and the time until the recovery of the printing function can be greatly shortened.

  Further, by making the scanning speed of the suction cap variable, the suction amount can be controlled for each nozzle group, and suction with the minimum ink amount necessary for recovering the printing function is enabled. As a result, it is possible to reduce the ink consumption, the amount of waste ink, and the waste ink receiving mechanism.

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

  FIG. 3 shows a conventional print function recovery mechanism. FIG. 1A shows a printing function recovery mechanism according to the embodiment of the present invention. With the suction pump 13 driven, the suction cap 30 formed of an elastic body such as rubber is brought into contact with the nozzle surface 07 with an elastic load such as spring pressure. Then, the suction cap 30 is moved in parallel with the nozzle row. As a result, the suction operation is performed while the nozzle groups to be sucked are sequentially switched. According to the present embodiment, as described in Japanese Laid-Open Patent Publication No. 2002-347260, since the suction area is significantly reduced compared to the conventional method of capping and sucking the entire nozzle surface, the same suction source is used. However, the real suction ability is improved.

  In this embodiment, since the ground contact area of the cap to the nozzle surface is small, it is possible to separate the cap 30 from the nozzle surface while the suction pump 13 is driven, and no air release function is required.

  Examples of the shape of the suction cap are shown in FIGS. As shown in FIG. 8, the nozzle surface abutting portion has a flat shape, the outer side has a slope shape facing the acute angle with respect to the nozzle surface, and the inner side has a vertical shape. Further, as shown in FIG. 1B, the direction orthogonal to the nozzle row has a shape that can sweep the entire nozzle surface. When the cap having such a shape scans in the nozzle row direction, the suction operation from the nozzle group and the blade 20 in the conventional mechanism (FIG. 4) scrapes the nozzle surface to remove ink droplets. The operation can be performed simultaneously.

  In the case of the embodiment of FIG. 8, the angle θ of the slope outside the nozzle is preferably approximately 45 degrees or less, and the width L of the nozzle contact portion is suitably about 0.1 to 0.3 mm.

  Further, as shown in FIG. 10, the nozzle abutting section cross-sectional shape of the suction cap in the nozzle scanning direction is one in which the nozzle abutting part is an edge shape in addition to the embodiment of FIG. 8 described above (FIG. 10-a), A nozzle contact portion having an R shape (FIG. 10B), an inner side of the nozzle contact portion having an acute angle shape (FIG. 10C), and the like are conceivable.

  With the suction cap shape, the suction cap scans the nozzle surface and sucks ink, and at the same time, the residual ink attached to the nozzle surface can be scraped and removed. This realizes a blade mechanism and a simple printing function recovery mechanism that does not require a preliminary ejection operation, which are necessary in the conventional mechanism.

  FIG. 9 shows the ink suction operation of the printing function recovery mechanism in the present invention. By making the speed at which the suction cap scans variable, the suction amount can be controlled for each nozzle group. For example, as shown in FIG. 9, when the suction starts, the cap is kept stationary for a while until the ink reaches, and then the nozzle group far from the ink supply port 05 is scanned at a low speed. Control is performed such that scanning is performed at high speed in the vicinity immediately below the supply port (near the center of the nozzle row), scanning is performed at low speed in the vicinity of the nozzle end, and suction is performed stationary at the end. Further, when scanning in a reciprocating manner, it is possible to further improve the suction efficiency and reliability by controlling the multi-directional scanning different from the forward direction.

  In addition, since the suction is always performed without performing the air release operation, the ink does not stay in the cap or does not flow backward. Therefore, a plurality of color nozzle rows as shown in FIG. Even when sucked, no color mixing occurs between colors.

  As described above, the air opening mechanism 12, the blade mechanism 20, and the preliminary discharge operation (FIG. 5) which are the conventional mechanisms are not required, and the substantial suction ability is improved and the printing function recovery mechanism is greatly simplified and the recovery operation time is shortened. Ink consumption can be reduced.

It is a schematic cross section which shows the printing function recovery mechanism of embodiment of this invention. It is a schematic cross section which shows the ink supply form of an inkjet head. It is a schematic cross-sectional view showing the configuration of a conventional printing function recovery mechanism. FIG. 10 is a schematic cross-sectional view showing blade operation in a conventional printing function recovery mechanism. It is a schematic cross-sectional view showing a preliminary discharge operation in a conventional printing function recovery mechanism. FIG. 10 is a schematic cross-sectional view showing ink flow during a suction operation in a conventional printing function recovery mechanism. It is a model perspective view which shows another suction cap form in embodiment of this invention. It is a three-view figure which shows the example of the suction cap in embodiment of this invention. It is a schematic cross section which shows another attraction | suction operation | movement in the printing function recovery mechanism of this invention. It is a schematic cross section which shows the example of the nozzle contact part shape of the suction cap in embodiment of this invention.

Explanation of symbols

01 Ink cartridge 02 Ink cartridge connection port 03 Ink flow path member 04 Nozzle unit 05 Ink supply port 06 Common liquid chamber 07 Nozzle surface 08 Nozzle 11 Suction cap 12 Atmospheric release valve 13 Suction pump 14 Waste ink receptor 20 Blade 30 Suction cap

Claims (8)

In a mechanism having an ink suction in an ink flow path of an ink jet head and a cleaning function of a nozzle surface of the head in an ink jet recording apparatus that discharges ink from a nozzle of the ink jet head and performs printing on a recording medium.
Means for sealing a predetermined nozzle group, negative pressure generating means for bringing the inside of the sealing means into a negative pressure state, means for bringing the sealing means into contact with the nozzle surface for scanning movement, and means for sealing the nozzle group Has a shape that also has a nozzle surface cleaning function by scanning with the scanning moving means.   2. A printing function recovery mechanism according to claim 1, wherein said negative pressure generating means does not require an atmospheric release mechanism / operation.   The cross-sectional shape in the nozzle scanning direction outside the nozzle surface abutting portion is a shape that is perpendicular or acute with respect to the nozzle surface. The printing function recovery mechanism according to claim 1.   2. The printing according to claim 1, wherein the means for sealing the nozzle group has a shape having a nozzle surface cleaning function, and the shape of the nozzle surface abutting portion is a flat surface, an edge shape, or an R shape. Functional recovery mechanism.   2. The printing function recovery according to claim 1, wherein the means for sealing the nozzle group has a function of cleaning the nozzle surface at the same time as suction, so that a preliminary ejection operation and a blade mechanism are not required. mechanism.   In the operation of abutting and scanning the means for sealing the nozzle group in the nozzle row direction, it is possible to change the suction time or the suction amount per nozzle as required by changing the scanning speed. The printing function recovery mechanism according to claim 1.   2. The nozzle group of a plurality of colors can be sucked without mutual color mixing by means of sealing a single nozzle group in an operation of abutting and scanning the means for sealing the nozzle group in the nozzle row direction. Print function recovery mechanism.   An ink jet recording apparatus having the printing function recovery mechanism according to claim 1.

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