JP2010264671A - Ink-jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of causing interference between paper and a head when the peak of cockling converges and increases in printing in electrostatic belt conveyance. <P>SOLUTION: A power supply roller for applying electric charge to an electrostatic conveyor belt, or the surface of a roller facing the power supply roller, is provided with regions (a) relatively low in resistance and regions (b) relatively high in resistance by providing a coating layer of high resistance. First regions relatively strongly attracted to the conveyor belt, and second regions relatively weakly attracted to the conveyor belt are thereby provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and a recording method provided with a mechanism for adsorbing a recording medium by electrostatic attraction means.

  2. Description of the Related Art Conventionally, in an ink jet recording apparatus that ejects ink droplets to form dots on a recording medium and forms an image, as a means for transporting the recording medium, paper is transported by a transport roller and a pinch roller that is driven by the transport roller. For example, there are a system in which the belt is sandwiched and a belt conveyance system in which a recording medium is attracted to the belt and the belt is transported. In this belt conveyance method, there is an electrostatic method in which static electricity is applied to the belt and the recording medium is attracted to the belt by electrostatic force as a method of attracting the recording medium to the belt.

  In general, in an ink jet recording apparatus, when a distance between a recording head and a conveyance belt (hereinafter referred to as a sheet interval) is large, ejected ink droplets are easily affected by wind, and a landing position on a recording medium is shifted. There is a case. In addition, when the gap between the papers is wide, minute ink droplets adhere to the vicinity of the ejection port of the head due to the air flow generated by ejection, which hinders ejection of the ink droplets.

  Furthermore, in the above electrostatic method, when the distance between the recording head and the conveyor belt is large, the electric field on the surface of the conveyor belt affects the ejected ink droplets, which causes problems such as ink being easily attached to the ink ejection port of the head. In some cases, it is necessary to narrow the gap between the recording head and the conveying belt.

  On the other hand, recording ink generally uses water as a main solvent. When the recorded image has a high density, a large amount of moisture is driven onto the recording medium, and the recording medium expands and increases in size. For this reason, it is known that a phenomenon that the recording medium undulates into a tin plate shape (hereinafter referred to as cockling) occurs in the printing unit, but there is no one that fundamentally solves this phenomenon. For the above-described reasons, when the gap between the recording head and the conveyance belt is narrowed, there is a problem that the recording medium becomes dirty due to interference between some recording media and the recording head due to the growth of the cockling.

  With respect to this problem, Patent Document 1 pays attention to restricting the height l by allowing the cockling to occur and then relatively strongly electrostatically attracting the recording medium in the ink recording area. A pair of comb-like electrode pairs under the electrostatic belt so as to alternately disperse a plurality of second regions that are relatively weakly electrostatically attracted to the first region. The cockling is reduced by making the second region correspond between the pair of comb-like electrodes.

  However, this configuration has a problem that it is necessary to separately provide a means such as disposing a large number of electrode pairs under the belt in order to disperse the cockling, which increases the cost. In addition, there is a problem that discharge occurs when the electrodes are too close together, and the cost increases by increasing the number of electrodes or changing the electrode width in the transport direction, and the configuration of the electrode spacing in the width direction and the configuration of the electrode width in the transport direction are limited. There is.

JP 7-1333035 A

  As described above, it is an object of the present invention to suppress the cockling at a low cost. The present invention has been made in consideration of the above-described facts, and is to provide an ink jet recording apparatus that solves the above technical problems and is inexpensive and has a high degree of design freedom.

  In order to achieve the above object, according to the first aspect of the present invention, the recording medium in the recording area is dispersed in a plurality of alternating first areas that are relatively strongly electrostatically attracted and second areas that are relatively weakly electrostatically attracted. Thus, a configuration is provided in which a plurality of strong power supply regions a and weak power supply regions b are alternately dispersed on the power supply roller. In this configuration, the cockling can be dispersed and the height can be suppressed only by providing a means for applying strength to the belt surface on the power supply roller, so that the cost can be reduced.

  Here, providing a strong charging area and a weak charging area on the surface of the transport belt is effective for reducing the cockling, but the problem is that the adsorption force decreases in proportion to the area of the weak charging area. There is. Invention of Claim 2 is the structure which can change the width | variety and shape of the weak electric power feeding area | region of Claim 1 according to the width | variety and rotation direction of an electric power feeding roller structure of Claim 1, and makes the area of a weak electric power feeding area | region small. Accordingly, the adsorption force to the recording medium can be made larger than that of the configuration of the power feeding roller of the first aspect. In this configuration, it is not necessary that the strong power feeding area and the weak power feeding area are regularly arranged on the power feeding roller, and the weak power feeding area of the weak power feeding area is determined according to the required adsorption force to the recording medium and the required amount of cockling suppression. Since the width and shape can be adjusted, a design with a wide degree of freedom is possible.

  The electrostatic belt conveyance device according to the present invention is configured to alternately disperse a plurality of b regions that are relatively weakly fed and a region that is relatively strongly fed by the power feeding roller installed. The cockling can be dispersed and the height can be suppressed at a low cost. In addition, since the width and shape of the b region of the power supply roller can be changed to the power supply roller width and the rotation direction according to the required adsorption force to the recording medium and the required amount of cockling suppression, the degree of freedom is wide. Design is possible.

Schematic diagram illustrating the nozzle arrangement of a recording head used in an embodiment of the present invention The figure explaining the conveyance part structure of an electrostatic belt conveyance system in the Example of this invention. The figure which looked at the conveyance part of the electrostatic belt conveyance system from the upper part in the example of the present invention. (A) The figure explaining the mode at the time of cockling generation | occurrence | production in the conventional power supply roller structure, (b) The figure explaining the mode at the time of cockling generation | occurrence | production in the power supply roller structure of this invention. (A) The schematic diagram explaining the structure of the conventional electric power feeding roller, (b) The schematic diagram explaining the comb-shaped electric power feeding roller in Example 1 of this invention. The figure which compares the maximum value of the cock ring in the structure of the conventional electric power feeding roller and the structure of the comb-tooth-shaped electric power feeding roller in Example 1 of this invention. The figure explaining the structure of the comb-tooth-shaped electric power feeding roller in Example 2 of this invention.

[Example 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Configuration of recording head)
FIG. 1 is a schematic diagram viewed from the nozzle surface of a recording head used in this embodiment. The recording head of this embodiment is composed of four colors, Yellow, Magenta, Cyan, and Black. Each color is arranged at 1/600 inch intervals of 256 nozzles, and the two rows are shifted by 1/1200 inch. It is a staggered arrangement. In the present recording head, as shown in the figure, the nozzle row direction coincides with the sub-scanning direction, which is the recording medium conveyance direction, and the direction perpendicular thereto is the main scanning direction in which the recording head reciprocates with printing. Match.

(Conveyor configuration)
The configuration of the transport unit, which is a feature of this embodiment, will be described with reference to FIGS. 2 is a cross-sectional view of the main scanning direction in which the recording head reciprocates as viewed from the front, and FIG. 3 is a plan view of the recording head as viewed from directly above. The same reference numerals are assigned to the same components.

  Reference numeral 1 denotes a recording head. The nozzle surface of the recording head shown in FIG. 1 is disposed in the lower part in FIG. 2, and ink droplets are ejected downward. Further, in FIG. 3, the reciprocation is performed with the direction indicated by the white arrow as the main scanning direction. The recording head is fixed to a carriage (not shown), and the carriage is supported by a carriage shaft (not shown), and performs reciprocating scanning along the carriage shaft. 2 is a platen part. The recording medium 8 is fed from a sheet feeding unit (not shown) and conveyed immediately below the recording head. The platen unit 2 supports the recording medium 8 from below in order to keep the distance between the sheets at an appropriate value by restricting vertical vibrations of the belt and the recording medium immediately below the recording head during conveyance. Reference numeral 4 denotes a driving roller that drives the conveyor belt 6. Reference numeral 5 denotes a driven roller that is driven. Further, in order to generate an electrostatic force for charging the conveyance belt and attracting the recording medium 8 to the conveyance belt, the three power supply rollers are brought into contact with the conveyance belt and supplied from a potential difference generator 9 connected to the power supply roller. Electric charge is supplied to the surface of the conveyor belt, and the surface of the conveyor belt is charged. In this configuration, the recording belt 8 is conveyed from the left side to the right side at a constant speed by the conveyance belt 6 rotating in the direction of arrow A in the figure. A pinch roller 7 is provided above the conveyance belt 6 on the upstream side of the recording area. A predetermined force acts on the pinch roller 7, whereby the recording medium 8 that is sandwiched and conveyed between the pinch roller 7 and the conveyance belt 6 is pressed against the conveyance belt 6 to the conveyance belt of the recording medium. Is surely adsorbed.

  FIG. 5A is a diagram illustrating the configuration of a conventional power supply roller, and FIG. 5B is a diagram illustrating the configuration of the power supply roller of the present invention. The configuration of the present invention of (b) corresponds to the region a corresponding to the first region on the belt that is relatively strongly charged on the power supply roller and the second region that is relatively weakly charged on the belt. A plurality of regions b are alternately provided. The region a is provided with a power supply means for charging the belt strongly and the region b is charged weakly on the belt, and the surface of the conveyor belt is charged by the charge supplied from the potential difference generating device 9. On the other hand, according to the configuration of the first embodiment, the belt surface is divided into a first region that is strongly charged and a second region that is weakly charged. In order to divide the belt surface into these two regions, for example, the material constituting the surface of the power supply roller can be realized by making the material having a low resistance value in the region a and the material having a high resistance value in the region b.

  Here, in the recording operation in the electrostatic belt conveyance recording apparatus described above, when the recorded image has a high density, the recording medium 8 shown in FIG. 2 was injected with a large amount of recording ink using water as a main solvent. As a result, the recording medium 8 swells and its dimensions increase. Here, although the recording medium 8 is adsorbed to the conveying belt 6, the swelling of the recording medium 8 cannot be suppressed, and the cockling occurs. At this time, in the configuration of the present invention, the strongly charged region 1 and the weakly charged region 2 on the belt surface are alternately extended along the conveyance direction of the recording medium 8. A strong and weak distribution of the attractive force is formed, and the swelling of the recording medium 8 can be generated in a plurality of weakly charged regions 2 having a low attractive force. That is, since a plurality of cocklings occur at a specific position, each cockling can be kept low.

  FIGS. 5A and 5B are schematic diagrams for explaining the characteristics of the cockling in (a) a conventional power supply roller configuration and (b) a power supply roller configuration of the present invention. In FIG. 5B of the present invention, it can be seen that the cockling occurs in the weakly charged second region on the belt corresponding to each high resistance region b, and the height l is reduced. FIG. 6 shows the measured maximum height of the cock ring. From these, the power feeding roller configuration of the present invention succeeds in reducing the cockling height as compared with the conventional power feeding roller configuration. Thus, in this configuration, the cockling can be dispersed and reduced by adjusting the widths of the low resistance region a and the high resistance region b. According to the configuration described above, since the cockling can be dispersed and suppressed only by providing means for alternately supplying power on the power supply roller, an inexpensive design is possible.

[Example 2]
Providing a strongly charged region and a weakly charged region on the surface of the conveyor belt is effective for absorbing the cockling, but as the area of the weakly charged region increases, the area of the strongly charged region decreases, and the conveyor belt The adsorbing power to the recording medium decreases. Here, as an example of a configuration in which the cockling is dispersed while maintaining the adsorption force to the recording medium, the configurations of FIGS. 7A and 7B are possible. In the configuration of FIG. 7A, the width of the high resistance layer is made as fine as possible in the b region of the feed roller, and the relative low resistance region and the relative high resistance region are alternately arranged, thereby forming a high resistance region. Since the area of the weakly charged region on the corresponding belt surface is smaller than that in the configuration of the first embodiment, the adsorption force to the recording medium is increased. 7B, the width of the high resistance region b ″ changes in the rotation direction of the power supply roller. In this configuration, the width of the high resistance region b is high in the configuration of the power supply roller of Example 1. Since the area is larger than that of the maximum width of the resistance region b ″ and the area of the high resistance region a ″ is smaller, the attractive force to the recording medium is larger than the configuration of the first embodiment. In this case, it is not necessary that the low resistance region and the high resistance region are regularly arranged in the width direction and the rotation direction on the surface of the power supply roller, and the low resistance region depends on the required amount of cockling suppression and the necessary adsorption force. , Since the width and shape of the high resistance region can be adjusted, the design can be performed with a wide degree of freedom.

  Up to this point, the configuration in which the power supply roller is provided with the relatively high resistance region b and the relatively low resistance region a has been described. In the embodiment of the invention, the same effect can be obtained even when the driving roller 4) is used.

Claims (4)

  In the recording apparatus that forms an image on the recording medium by adsorbing and conveying the recording medium by electrostatic force generated by applying an electric charge to the conveying belt by the power supply roller, and ejecting droplets from the recording head. A first region that is provided with a plurality of regions b in which the surface of the power supply roller or the roller facing the power supply roller has a relatively low resistance and a region b that has a relatively high resistance and is relatively strongly adsorbed to the conveyor belt; 2. An ink jet recording apparatus comprising a plurality of second areas that are relatively strongly adsorbed and dispersed.   2. The inkjet recording apparatus according to claim 1, wherein a high resistance coating layer is provided on a surface of the power supply roller or a roller facing the power supply roller, so that the surface of the roller facing the power supply roller or the power supply roller is relatively high. An ink jet recording apparatus, wherein a region b having a resistance and a region a having a relatively low resistance are provided.   The inkjet recording apparatus according to claim 1 or 2, wherein there are a plurality of types of widths in the roller axial direction of the plurality of regions a to b provided on the power supply roller or the roller facing the power supply roller. Inkjet recording device.   The width of the area | region a thru | or the area | region b provided in the roller which opposes the said electric power supply roller or an electric power supply roller in the inkjet recording device of Claim 1 thru | or 3 is not constant in a roller axial direction. An ink jet recording apparatus.