JP2005246832A - Ink-jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording device capable of performing a stable and excellent ink-printing operation without making a recording paper touch the ink-discharge port, as a simple and inexpensive structure. <P>SOLUTION: A head unit 10 is provided with a guide part 20a having two or more line-contact positions guiding the recording surface of the recording paper P so that the paper P does not get into contact with the discharge port 10, at the conveying-passage upstream of the discharge port 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus that uses an image recording apparatus or a printing apparatus to record an image on recording paper by discharging ink.

  In recent years, an inkjet image recording apparatus can easily and inexpensively create an image, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter. In particular, a recording device that controls the amount of ink discharged so as to form a fine dot image, an ink with improved color reproduction range, durability, and emission suitability, ink absorbency, colorant coloring, surface gloss By using special paper with dramatically improved image quality, it is possible to form images with image quality comparable to silver halide photography. As described above, today, an inkjet image recording apparatus achieves high-quality image formation by greatly improving the recording apparatus, ink, and special paper.

  Conventionally, water-soluble liquid ink compositions (water-based inks) have been widely used as ink-jet recording ink compositions, and fine dot images are formed by ejecting ink onto recording paper that maintains flatness.

  By the way, as one of the problems of the ink jet method using the water-based ink, there is a generation of a wavy (cockle) on the recording paper.

  This is because the water in the water-based ink (hereinafter simply referred to as ink) permeates between the paper pulp fibers shaped into a flat shape, so that the pulp fibers can move freely to some extent. The entanglement changes and expands locally, resulting in a volume change and undulation. This appears remarkably in the solid image portion where the amount of ink increases.

  When this undulation occurs, not only the undried image is disturbed, but also in the worst case, the convex surface of the recording paper rubs the ink discharge port surface of the head unit, so that unnecessary ink adheres to the recording paper and the recording paper surface becomes In addition to being soiled, the ejection direction is changed by the occurrence of non-ejection nozzles, the water-repellent treatment agent provided on the surface of the ink ejection port peels off, the ink adheres to the periphery of the ejection port, and the ink droplets are pulled to it during ejection. This causes various print quality defects such as changes.

In order to maintain a predetermined gap between the ink discharge port surface of the head unit and the recording paper recording surface, the belt, roller, platen, or the like that supports the recording paper from below is provided upstream or downstream to the discharge port. It has been proposed to provide a pressing means such as a spur or a roller that comes into contact with the member so as to prevent the recording paper from rising or wavy and to prevent the recording paper from contacting the ink discharge port. Then, when a conveyance abnormality occurs in which the pressing means supported by the arm that presses and regulates the recording paper has a displacement or pressure exceeding a predetermined value, the recording operation is stopped and the pressing means is opened. Yes. (For example, refer to Patent Document 1 and Patent Document 2.)
JP 2001-26154 A JP 2002-113910 A

  In the method of pressing the recording paper by the pressing means disclosed in Patent Literature 1 and Patent Literature 2 and regulating the position of the recording paper, the position is regulated at the pressed location. However, it is extremely difficult for the pressing means using such spurs and rollers to be provided close to the ink discharge port, and the restriction position by the ink discharge port and the pressing means is located apart from the meantime. On the other hand, there is a situation in which the recording paper floats or undulates and contacts the ink ejection port.

  The present invention provides an ink jet recording medium that is transported so that the recording paper does not come into contact with the ink discharge port and stably prints without using a pressing means such as a spur or a roller. An object is to provide a recording apparatus.

  In order to solve the above problems and achieve the object, the present invention is configured as follows.

(Claim 1)
In an inkjet recording apparatus having a head unit that records an image by ejecting ink from an ejection port, and a conveyance path that conveys recording paper,
The ink jet recording, wherein the head unit is provided with a guide member that guides a recording surface of the recording paper so that the recording paper does not come into contact with the discharge port on the upstream side of the transport path from the discharge port. apparatus.

(Claim 2)
The inkjet recording apparatus according to claim 1, wherein the guide member has a plurality of line contact portions in parallel with a conveyance direction of the recording paper.

(Claim 3)
The inkjet recording apparatus according to claim 1 or 2, wherein a distance between a plurality of line contact portions that contact the recording paper of the guide member is 2 to 40 mm.

(Claim 4)
The distance between the rear end of the line contact portion of the guide member with the recording paper and the recording position closest to the recording position by the discharge port is 1 to 10 mm. 2. An ink jet recording apparatus according to item 1.

(Claim 5)
The inkjet recording apparatus according to any one of claims 1 to 4, wherein the length of the line contact portion is 50 mm or less.

(Claim 6)
The distance between the discharge port surface of the head unit and the recording surface of the recording paper is regulated between 0.3 and 3.0 mm. Inkjet recording apparatus.

(Claim 7)
The inkjet recording apparatus according to claim 1, wherein the guide member is made of resin.

(Claim 8)
The ink jet recording apparatus according to claim 1, wherein the guide member has conductivity.

  According to the present invention, since the guide member is provided in the head unit, the guide member is set close to the upstream side of the discharge port and at a height required by the guide member at the minimum with respect to the discharge port surface. Thus, the recording paper does not rub against the discharge port surface, and even if the paper thickness of the recording paper changes, the interval between the recording surface of the recording paper and the discharge port surface can be made the same. By providing the guide member integrally with the head unit, it is possible to set the distance between the recording surface of the recording paper and the discharge port surface that is close and more accurate and inexpensive. Further, in the present invention, compared to the conventional recording paper conveyance regulating means, the interval between the recording surface of the recording paper and the ejection port surface can be set short, and therefore, particularly due to the ink droplet ejection angle error. The occurrence of density unevenness and white spots can be suppressed.

  An example of an embodiment of the present invention will be described with reference to the drawings. The description in this column does not limit the technical scope of the claims or the meaning of terms.

  FIG. 1 shows a head unit 10 that records an image by ejecting ink from ejection ports (also referred to as nozzles). 1A is a front view, FIG. 1B is a side sectional view, and FIG. 1C is a bottom view, and shows the conveyance direction of the recording paper P with respect to the head unit 10 with an arrow.

  In the head unit 10 shown in this embodiment, a plurality of discharge ports 12 are arranged in a planar nozzle plate 11 subjected to water repellent treatment at equal intervals perpendicular to the recording paper transport direction. The same color ink is ejected independently.

  The ink used here is a water-based inkjet ink containing 10% by mass or more of water per total mass of the ink. As a means for ejecting ink, a system using a piezo element as an actuator or a system for ejecting ink with pressure of bubbles formed by an electrothermal conversion element is employed.

  In the head unit 10, a guide member 20 having a guide portion 20 a that guides the recording surface of the recording paper so that the recording paper does not come into contact with the discharge port 12 is provided on the upstream side of the conveyance path from the discharge port 12. By the coupling means, the nozzle plate 11 is attached integrally with the head unit 10 with the attachment reference. The guide portion 20a may be configured to be molded integrally with the nozzle plate 11 of the unit 10.

  The guide portion 20a is formed in a shape in which line contact is made with the recording paper P by a tip portion having a plurality of cross-sectionally inverted triangles in parallel with the conveyance direction of the recording paper P, and the interval between the adjacent guide portions 20a is It is set between 2 and 40 mm.

  If the distance between the guide portions 20a is less than 2 mm, the contact portion increases between the recording paper P and the guide portion 20a, resistance occurs in the recording paper conveyance, friction charging occurs, and conveyance failure occurs, which is not preferable. . Further, if the interval between the guide portions 20a exceeds 40 mm, the recording paper guided by the guide portion 20a has a variation in the conveying posture, such as lifting and undulation, and the interval between the discharge port surface and the recording surface in the discharge port 12 is increased. This is not preferable because it varies.

  In order to prevent the paper dust or the like of the conveyed recording paper from adhering to the guide portion 20a and to suppress charging that adversely affects the conveyance of the recording paper, it is desirable that the guide member 20 has conductivity, and plastic In addition, a conductive resin kneaded with carbon or metal powder or fiber is used. As the resin, polyacetal (POM) is preferably used, and the guide member 20 made of a conductive resin is grounded through a member (not shown).

  FIG. 2 is an enlarged view of a main part in the vicinity of the discharge port 12.

  The head unit 10 includes a support member 30 that supports recording paper with a predetermined interval. The supporting member 30 is a driven or driven rotating roller, belt, fixed platen or the like, and the recording paper has a gap of about 100 μm between the supporting member 30 and the guide portion 20a (indicated by d3 in the figure). It moves by being guided and passes through while maintaining a slight gap on the surface of the discharge port 12. With such a configuration, there is an effect of restricting the conveyance of the recording paper and reducing the amount of paper corrugation. The support member 30 may be configured to be finely adjusted according to the thickness of the recording paper to be recorded.

  The distance (indicated by d1 in the figure) between the rear end of the contact portion of the guide portion 20a with the recording paper and the recording position closest to the recording position by the discharge port 12 is set between 1 and 10 mm. . The head unit 10 is provided with a bowl-shaped cap member (not shown) that simultaneously covers the plurality of ejection ports 12 for the purpose of sucking ink from the nozzle plate 11 side during maintenance. Although it is more effective if the distance d1 between the rear end of the guide portion 20a and the discharge port 12 is closer, if the distance is too close, the nozzle plate 11 has no space for applying the suction cap member. Accordingly, the distance d1 between the rear end of the guide portion 20a and the discharge port 12 is determined in consideration of the shape of the cap member. If the distance d1 exceeds 10 mm, the recording paper deviated from the rear end of the guide portion 20a is not preferable because the gap between the discharge port 12 and the surface of the discharge port 12 varies.

  The recording paper P is stably conveyed toward the ejection port 12 using the gap d3 between the guide portion 20a and the support member 30 as a conveyance path. The interval of the recording surface with respect to the surface of the discharge port 12 at the position of the discharge port 12 (shown by d2 in the figure) is determined by the height of the guide portion 20a with respect to the surface of the discharge port 12. The interval d2 between the ejection port 12 surface and the recording surface is set to a constant value between 0.3 and 3.0 mm. When the distance d2 between the surface of the ejection port 12 and the recording surface is less than 0.3 mm, a part of the ink ejected from the ejection port 12 toward the recording surface rebounds from the recording surface and adheres to the ejection port 12 and becomes unaffected. A discharge port is generated. On the other hand, when the distance d2 exceeds 3.0 mm, the ink ejected from the ejection ports 12 is likely to vary during flight, and a reduction in print quality is recognized.

  In the ink jet recording apparatus of the present embodiment, there is no member for nipping and transporting the recording paper near the printing unit. Therefore, in order for the recording paper to be transported in a stable manner and to be printed at the discharge port 12, It is necessary to set the length (L1 appearing in FIG. 1 (b)) of the line contact portion to 50 mm or less.

  FIG. 3 shows an ink jet printer that prints a color image using the head unit 10 provided with the guide member 20 of the present invention. 3A is a side view and FIG. 3B is a top view. Both are line heads, and color image recording is performed on the recording paper P without moving the head.

  In the figure, the recording paper P is nipped by a conveyance roller composed of a driving roller 41A and a driven roller 41B and advances straight, and enters the head unit 10 for discharging K ink. A support roller 30A that rotates following the head unit 10 is provided, and the guide portion 20A and the support roller 30A maintain an interval d3 (300 μm in this embodiment), and the recording paper P is between the intervals d3. The recording surface is printed with K ink in a state of passing through and maintaining a predetermined distance from the surface of the ejection port 12.

  The recording paper P that has been printed with K ink is sandwiched and conveyed by a spur 42C that is driven to rotate on the recording surface side and a driving roller 42A on the back surface side, and enters the head unit 10 that discharges C ink. Printing with C ink is performed on the printed image.

  Similarly, printing with M ink is performed on a print image with C ink, and further printing with Y ink is performed thereon. After the color image is recorded using the four colors of ink, the recording paper P is sandwiched between the spur 42C and the driving roller 42A and discharged from the ink jet printer.

The block diagram of a head unit. FIG. 3 is an enlarged view of the vicinity of an ink ejection port. The block diagram of an inkjet printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Head unit 11 Nozzle plate 12 Discharge port 20 Guide member 20a Guide part 30 Support member

Claims (8)

In an inkjet recording apparatus having a head unit that records an image by ejecting ink from an ejection port, and a conveyance path that conveys recording paper,
The ink jet recording, wherein the head unit is provided with a guide member that guides a recording surface of the recording paper so that the recording paper does not contact the discharge port on the upstream side of the transport path from the discharge port. apparatus. The inkjet recording apparatus according to claim 1, wherein the guide member has a plurality of line contact portions in parallel with a conveyance direction of the recording paper. The ink jet recording apparatus according to claim 1 or 2, wherein an interval between a plurality of line contact portions that contact the recording paper of the guide member is 2 to 40 mm. The distance between the rear end of the line contact portion of the guide member with the recording paper and the recording position closest to the recording position by the discharge port is 1 to 10 mm. 2. An ink jet recording apparatus according to item 1. The inkjet recording apparatus according to any one of claims 1 to 4, wherein a length of the line contact portion is 50 mm or less. The distance between the discharge port surface of the head unit and the recording surface of the recording paper is regulated between 0.3 and 3.0 mm. Inkjet recording apparatus. The inkjet recording apparatus according to claim 1, wherein the guide member is formed of a resin. The inkjet recording apparatus according to claim 1, wherein the guide member has conductivity.

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