JP2007253450A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer which can more positively make ink droplets hit on a target hitting position, and can also shorten a printing necessary time. <P>SOLUTION: The ink is charged, for example, to (+) by an ink charging means. At the same time, a hitting auxiliary electrode 14 of a potential (-) of an opposite polarity to that of the charging potential of the ink is installed at the opposite side of nozzles of an inkjet head 11 via a conveyance belt 1 to be held between plane regulation bodies 13 in a non-contact manner to the conveyance belt 1. The ink droplets are made to fly by an electrostatic force towards the hitting auxiliary electrode 14. The ink droplets are thus more positively hit on the target hitting position. At the same time, the printing necessary time is shortened by increasing a flying speed of the ink droplets. Moreover, the effect of attracting the ink droplets is made sure by eliminating the charging at the upstream side of the hitting auxiliary electrode 14, and conveyance of a printing medium 2 is ensured by charging again at the downstream side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention adsorbs and conveys a printing medium such as recording paper onto the surface of a conveying belt, and discharges, for example, fine particles (dots) of liquid ink of a plurality of colors onto the printing medium to draw predetermined characters and images. The present invention relates to an inkjet printer.

Such inkjet printers are generally inexpensive and can easily obtain high-quality color prints, and therefore have become widespread not only in offices but also in general users with the spread of personal computers and digital cameras.

In such an ink jet printer, generally, a moving body called a carriage or the like, which is integrally provided with an ink cartridge and an ink discharge head (generally called an ink jet head), runs on a print medium in a direction intersecting the transport direction. By driving the actuator while reciprocating, the liquid ink particles are ejected (jetted) from the nozzles formed on the ink jet head, thereby forming minute ink dots on the print medium, thereby forming predetermined characters and images. Is drawn to create a desired printed matter. The carriage is equipped with four color (yellow, magenta, cyan) ink cartridges including black (black) and an inkjet head for each color, so that not only monochrome printing but also full-color printing combining each color is easy. (Furthermore, 6 colors, 7 colors, or 8 colors in which light cyan, light magenta, etc. are added to these colors are also put into practical use).

In addition, in an ink jet printer that performs printing while reciprocating the ink jet head on the carriage in the direction intersecting the print medium conveyance direction (width direction of the print medium), the entire page is printed neatly. Therefore, it is necessary to reciprocate the inkjet head several tens of times to 100 times or more. In contrast, in an inkjet printer of a type that does not use a carriage with a long (not necessarily integral) inkjet head having the same dimensions as the width of the print medium, the inkjet head is moved in the width direction of the print medium. Therefore, it is possible to perform printing in a so-called one pass, so that high-speed printing is possible. The former inkjet printer is generally referred to as a “multi-pass inkjet printer”, and the latter inkjet printer is generally referred to as a “line head inkjet printer”.

By the way, in this type of line head type ink jet printer, a configuration is often used in which a print medium is electrostatically adsorbed and conveyed on an endless belt for conveyance. In order to electrostatically attract the print medium with the conveyance belt, it is necessary to apply a charge to the conveyance belt to charge it, but the electric field due to this charge acts on the ink droplets, and there are problems with ink ejection such as flight bending. May occur. Flying bend means that the ink droplets ejected from the nozzle do not fly on the ideal trajectory,
It means that it deviates from the ideal output position (also called landing position). In particular, in a line head type ink jet printer, since printing is performed in a so-called one pass, a printing result is remarkably lowered only by an ink ejection failure occurring in one of a large number of nozzles.

Therefore, in the ink jet printer described in Patent Document 1 below, an electrode is provided in the vicinity of the gap between the ink jet head and the print medium, and the charging of the flying ink droplet is forcibly neutralized by applying an AC voltage to the electrode. Has been proposed. In addition, the inkjet printer described in Patent Document 2 below performs so-called AC charging in which the polarity is alternately reversed along the moving direction of the transport belt, and transports so that the lines of electric force draw a minute loop between the positive and negative charging portions. An electric field is generated in the vicinity of the belt, and the print medium is electrostatically adsorbed by using an electric field that does not extend far from the conveyor belt. Further, in the ink jet printer described in Patent Document 3 below, a control electrode is provided around the nozzle for ejecting ink droplets, and a voltage is applied to the control electrode at the timing of ejecting ink droplets, so that an electric field between the transport belt and the ink jet head is applied. We are trying to weaken or reverse.
JP-A-4-83644 JP 2003-103857 A JP 2000-25249 A

However, in the prior art, the charging of the ink droplet is removed or the influence of the electric field of the flying portion of the ink droplet is alleviated, and the ink droplet is not intended to land more aggressively at the target landing position. Absent. In addition, the flying bend of ink droplets may be caused by paper dust or ink mist adhering to the vicinity of the nozzle, individual differences in the ink droplet ejection direction of the nozzle itself,
In the prior art, it is not possible to make the ink droplet land at the target landing position by correcting the flight bend based on these causes.

The present invention has been made paying attention to the above-described problems, and provides an ink jet printer that can more positively land ink droplets at a target landing position and reduce the time required for printing. It is for the purpose.

[Invention 1] In order to solve the above-described problems, the ink jet printer of Invention 1 carries a print medium by placing the print medium on the surface of the conveyance belt, and ejecting ink droplets from the nozzles of the ink jet head onto the print medium for printing. In the ink jet printer that performs the above, an ink charging unit that charges the ink to a predetermined polarity, and a non-contact arrangement of the ink jet head on the opposite side of the nozzle of the ink jet head across the transport belt and the reverse of the charging potential of the ink A landing auxiliary electrode having a polar potential; and a neutralizing electrode disposed at a position spaced apart from the landing auxiliary electrode on the upstream side in the printing medium conveyance direction from the landing auxiliary electrode and removing the charging of the conveyance belt. It is a feature.

According to the ink jet printer according to the first aspect of the invention, the ink is charged to a predetermined polarity by the ink charging unit, and on the opposite side of the nozzle of the ink jet head across the transport belt,
By arranging the landing auxiliary electrode having a polarity opposite to the charging potential of the ink in contact with the conveyor belt, the ink droplets fly toward the landing auxiliary electrode by electrostatic force, so the position of the landing auxiliary electrode By appropriately setting, ink droplets can be landed more actively at the target landing position, and the flight speed can be increased on the ink droplets, so that the time required for printing can be shortened. In addition, by providing a static elimination electrode for removing the charging of the conveying belt at a position separated from the landing auxiliary electrode upstream of the landing auxiliary electrode in the printing medium conveying direction, Remove the effect of the electric field on the ink droplets,
The ink droplet can be landed on the target landing position.

[Invention 2] The inkjet printer of Invention 2 is characterized in that, in the inkjet printer of Invention 1, the distance between the landing auxiliary electrode and the static elimination electrode is made larger than the distance between the landing auxiliary electrode and the nozzle of the inkjet head. To do.
According to the ink jet printer according to the second aspect of the present invention, the ink droplets ejected from the nozzles of the ink jet head can be obtained by making the distance between the landing auxiliary electrode and the static elimination electrode larger than the distance between the landing auxiliary electrode and the nozzle of the ink jet head. It is possible to suppress and prevent the influence of the static elimination electrode on the flight of the vehicle.

[Invention 3] The inkjet printer according to Invention 3 is the inkjet printer according to Invention 1 or 2, wherein an insulating plane regulating body for regulating the plane of the conveyance belt and the print medium is provided between the landing auxiliary electrode and the discharge electrode. It is characterized by being interposed.
According to the ink jet printer according to the third aspect of the present invention, the insulating plane regulation body that regulates the plane of the conveyance belt and the print medium is interposed between the landing auxiliary electrode and the static elimination electrode.
It is possible to ensure insulation between the landing auxiliary electrode and the static elimination electrode and to secure a distance between the landing auxiliary electrode and the static elimination electrode.

[Invention 4] The inkjet printer according to Invention 4 is the inkjet printer according to any one of Inventions 1 to 3, in which the conveyance belt is charged at a position separated from the landing auxiliary electrode downstream of the landing auxiliary electrode in the printing medium conveyance direction. A charging electrode is provided.
According to the ink jet printer according to the fourth aspect of the invention, the ink droplets are formed by providing the recharging electrode for charging the conveying belt at a position separated from the landing auxiliary electrode on the downstream side in the printing medium conveying direction from the landing auxiliary electrode. The discharged print medium can be reliably electrostatically adsorbed to the transport belt.

[Invention 5] The inkjet printer of Invention 5 is characterized in that, in the inkjet printer of Invention 4, the distance between the landing auxiliary electrode and the recharging electrode is larger than the distance between the landing auxiliary electrode and the nozzle of the inkjet head. It is what.
According to the ink jet printer according to the fifth aspect of the invention, the distance between the landing auxiliary electrode and the recharging electrode is made larger than the distance between the landing auxiliary electrode and the nozzle of the ink jet head, so that the ink droplets discharged from the nozzle of the ink jet head are discharged. The influence of the recharged electrode on the flight of can be suppressed and prevented.

[Invention 6] The inkjet printer according to Invention 6 is the inkjet printer according to Invention 4 or 5, wherein a plane regulating body for regulating the plane of the conveyance belt and the printing medium is interposed between the auxiliary landing electrode and the recharging electrode. It is characterized by that.
According to the ink jet printer of the sixth aspect of the present invention, since the insulating plane regulating body that regulates the plane of the conveyance belt and the print medium is interposed between the landing auxiliary electrode and the recharging electrode, It is possible to ensure insulation from the recharging electrode and to secure a distance between the landing auxiliary electrode and the recharging electrode.

Next, an embodiment of an inkjet printer according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an ink jet printer according to the present embodiment. Reference numeral 1 in the figure is
It is a conveyance belt for conveying the printing medium 2 such as printing paper. The printing medium 2 is a sheet material made of a high resistance material such as printing paper or an OHP sheet. The conveyor belt 1 is an endless belt made of a medium / high resistance material made of a material as described later. The conveyor belt 1 is wound around a driving roller 3 disposed at the left end portion in the figure and a driven roller 4 disposed at the right end portion in the figure.

The drive roller 3 is driven to rotate in the direction of the arrow in the figure by a drive source (not shown), and the print medium 2 is sucked from the right side of the figure in a state where the print medium 2 is attracted to the conveyance belt 1 charged by the charging roller described later. Transport to the left, that is, in the direction of the arrow. The drive roller 3 is grounded so as to remove charges from the conveying belt 1, so-called static elimination. The tension of the conveyor belt 1 is adjusted by a configuration such as using a tension roller (not shown) to expand the belt downward in the figure, or pulling either the driving roller 3 or the driven roller 4 outward with a spring, etc. It's not going out.

A charging roller 7 as a charging unit is in contact with the conveyor belt 1 so as to face the driven roller 4, and a positive (+) pole DC power supply 8 is connected to the charging roller 7. The arrangement of the charging roller 7 corresponds to immediately before the feeding position of the printing medium 2. The charging roller 7 is charged by applying a positive (+) pole charge to the surface of the conveyance belt 1, generates dielectric polarization in the print medium 2 by the charge, and the print medium 2 side of the print medium 2 by the dielectric polarization is charged. The print medium 2 is attracted to the surface of the conveyor belt 1 by electrostatic force due to the electric charge of the toner and the charge on the surface of the conveyor belt 1. The charging roller 7 is pressed against the conveyor belt 1 by a spring (not shown).

A pressure roller 9 may be disposed above the driven roller 4 as shown. The pressure roller 9 is urged downward by a spring (not shown) and has a function of pressing the print medium 2 against the conveyance belt 1 on the driven roller 4. Since the printing medium 2 has irregularities of about 10 to several tens of μm, and there are wrinkles, warping, sagging, and bending, the printing medium 2 can be transferred to the conveying belt 1 just by feeding the printing medium 2 onto the conveying belt 1. It does not adhere to.

Therefore, after the printing medium 2 is mounted on the outer peripheral surface of the charged conveyance belt 1, when the printing medium 2 is pressed against the conveyance belt 1 by the pressure roller 9, it is attracted to the outer peripheral surface of the conveyance belt 1 by the dielectric polarization as described above. The printed medium 2 is further closely attached and transported with increased suction force,
Since the surface smoothness of the print medium 2 is increased and the uniformity of the gap with the head nozzle is improved, the print quality is also improved. A gate roller (not shown) is arranged on the upstream side of the pressure roller 9 in the conveyance direction of the print medium 2. This gate roller is used to adjust the timing at which the print medium 2 fed from the paper feed unit is fed onto the transport belt 1 and to bend the print medium 2 in the transport direction, so as to correct a so-called skew.

Reference numeral 11 in FIG. 1 is a line-type inkjet head. The inkjet head 11 is shifted in the transport direction of the printing medium 2 for each of a plurality of necessary combinations of colors such as four colors of yellow (Y), magenta (M), cyan (C), and black (K). Arranged. Ink is supplied to each inkjet head 11 from an ink tank of each color (not shown) via an ink supply tube.

Each inkjet head 11 is formed with a plurality of nozzles in a direction intersecting with the transport direction of the print medium 2, and by ejecting a necessary amount of ink droplets from these nozzles to necessary places as appropriate, the print medium 2. A minute ink dot is formed and output on the top. By performing this for each color, it is possible to perform so-called one-pass printing by passing the print medium 2 adsorbed on the conveyor belt 1 once. That is, the area where the inkjet head 11 is disposed corresponds to the print area. In the present embodiment, the conveyance speed of the print medium 2 is set to 200 mm / s or less.

There are various methods for ejecting and outputting ink from each nozzle of the ink jet head, such as a piezo method and a thermal method, and any ink output method can be applied to the present invention. The in-type inkjet head of the present embodiment literally has a “single row” nozzle configuration. However, as described in, for example, Japanese Patent Application Laid-Open No. 7-81049, a relatively short nozzle row module is inclined or staggered. It may be arranged in a shape. In this embodiment, it is important that the inkjet head is fixed.

A plane forming portion 12 is provided below the inkjet head 11 constituting the printing area so as to face the inkjet head 11. The plane forming unit 12 is generally called a platen, and regulates the flat surface of the print medium 2 via the conveyance belt 1 when ejecting ink droplets from the inkjet head 11. Details of the plane forming portion 12 will be described later.

The conveyance belt 1 is made of nylon, polyester, polyurethane, P as a base resin.
Fluorine resin such as ET, polycarbonate, silicon, PVDF, etc. is applied, and carbon black or conductive filler is mixed into this to have a volume resistance of 10 ⁸ to 10 ¹⁵ Ω · cm.
The degree is adjusted to about 10 ⁹ to 10 ¹² Ω · cm. The thickness of the conveyor belt 1 is
Considering durability and flexibility, charging at high speed and static elimination characteristics, etc., that is, from the viewpoint of compatibility between static elimination / power feeding efficiency and mechanical strength, 0.05 to 0.5 mm, more preferably 0.1 to 0. Select about 2mm.

In FIG. 2, the detail of the plane formation part 12 is shown. In the present embodiment, two plane regulation bodies 13 are disposed for each of the four color nozzle rows of the inkjet head 11 described above, and landing auxiliary electrodes 14 are disposed therebetween. The circles in the figure represent the nozzles of the inkjet head 11. In other words, the plane regulating body 13 and the landing auxiliary electrode 14 are disposed on the opposite side of the nozzle of the inkjet head 11 with the conveyance belt 1 interposed therebetween. In this embodiment, the landing auxiliary electrode 14 is directly below the nozzle of the inkjet head 11. It is arranged.

FIG. 3 shows the plane restricting body 13 and the landing auxiliary electrode 14 that are arranged to face one nozzle row. The plane regulating body 13 is called the platen described above, is made of an insulating material such as plastic, and is formed with a plane portion 13a that contacts the back surface (inner circumferential surface) of the transport belt 1. In addition, on the upstream side of the landing auxiliary electrode 14 in the print medium conveyance direction, the static elimination electrode 15 is disposed so as to be in close contact with the plane regulation body 13 with the plane regulation body 13 interposed therebetween. Also,
A recharging electrode 16 is disposed on the downstream side of the landing auxiliary electrode 14 in the print medium conveyance direction so as to be in close contact with the plane regulating body 13 with the plane regulating body 13 interposed therebetween.

FIG. 4 shows details of the landing auxiliary electrode 14, the inkjet head 11, the charge removal electrode 15, and the recharging electrode 16. The landing auxiliary electrode 14 is disposed between the two plane regulating bodies 13 so as to be sandwiched between the two but is not in contact with the transport belt 1. The landing auxiliary electrode 14 has a negative (−) pole and is configured by a thin blade (thin plate) in the print medium conveyance direction. As will be described later, this is to limit the landing position of the ink droplets to a narrow range. By using the blade, it is possible to easily cope with the above-described inclined or staggered inkjet head nozzles. On the other hand, a positive (+) electrode charge is applied to the inkjet head 11 as ink charging means, and the inkjet head 11 and the ink inside the inkjet head 11 are also charged to the positive (+) electrode. The static elimination electrode 15 is for removing the charge (charge) of the transport belt 1, is composed of a negative (−) electrode, and is in contact with the transport belt 1. The recharging electrode 6 is for recharging the conveyor belt 1 and is composed of a positive (+) pole blade electrode and is in contact with the conveyor belt 1.

The landing auxiliary electrode 14 uses a conductive plastic blade in which resistance is adjusted by mixing carbon black or conductive filler with various plastics, and its volume resistance value is 10 ⁹ to 10 ¹² Ω · Adjust to medium or high resistance of about cm. The clearance between the landing auxiliary electrode 14 and the conveyor belt 1 is in a non-contact state within a range not exceeding 1 mm. Landing auxiliary electrode 1
The dimension in the height direction of 4, that is, the thickness in the energizing direction is about 3 mm or more. Further, if the shape of the landing auxiliary electrode 14 on the ink jet head nozzle side is sharp, it is easy to discharge. Therefore, the tip of the landing auxiliary electrode 14 on the ink jet head nozzle side has an R shape, the radius of curvature of the R shape is 2 mm or less, and 0.5 mm or less when performing high-density mounting.

The potential of the inkjet head 11 is +500 V to +1000 V, and the landing auxiliary electrode 1
The potential of 4 is -1000V to -1500V so that the overall potential difference does not exceed 2000V. (If it exceeds 2000 V, there is a risk of leak discharge). When ink droplets are ejected from the nozzles of the inkjet head 11, the ink droplets charged to the positive (+) electrode are repelled by the electrostatic force with the inkjet head 11 and are attracted by the electrostatic landing force to the negative (−) electrode landing auxiliary electrode 14. To fly.

The flying ink droplets are the force ejected from the inkjet head 11, the force received from the electric field of the landing auxiliary electrode 14, the air resistance (toward the inkjet head 11), and the printing medium 2.
The aircraft flies in balance with the force received from the air (wind) flowing upward and landed on the print medium 2. Among these, the air (wind) flowing on the print medium 2 is a wind generated when an object (in this case, the print medium 2) moves at a high speed, and in the present embodiment, the print medium 2 is conveyed. Since the speed is set to 200 mm / s or less, there is no need to consider it. In addition, when the conveyance speed of the printing medium 2 is larger than this, the air flow generated according to the conveyance speed is taken into consideration, and accordingly,
You may make it arrange | position the auxiliary landing electrode 14 with respect to a nozzle in the printing medium conveyance direction downstream.

The neutralization electrode 15 and the recharging electrode 16 are made of conductive plastic blades in which various plastics are mixed with carbon black or conductive filler to adjust the resistance, and the volume resistance value is about 10 ⁴ to 10 ¹⁰ Ω · cm. adjust. The static elimination electrode 15 and the recharging electrode 16 must be in contact with the conveyance belt 1 from their respective functions. Further, the dimension in the height direction of the static elimination electrode 15 and the recharging electrode 16, that is, the thickness in the energization direction is about 3 mm or more. The static elimination electrode 15 and the recharging electrode 16 do not need to limit the ink droplet landing positions unlike the landing auxiliary electrode 14 and may be roller electrodes.

The electric potential of the static elimination electrode 15 is adjusted to a value at which the charge (charge) of the conveying belt 1 can be completely or almost completely removed in order to ensure the ink droplet suction effect by the landing auxiliary electrode 14 described above. If the object can be achieved, the ground potential may be used. In order to restore the print medium electrostatic adsorption force of the conveyor belt 1 removed by the static elimination electrode 15, the potential of the recharging electrode 16 is
The outer peripheral surface potential of the conveying belt 1 after the charge is applied is 300V to 1000V, preferably 500V to
Adjust to 800V.

Further, the distance between the landing auxiliary electrode 14 and the static elimination electrode 15 and the landing auxiliary electrode 14 and the recharging electrode 1
6 is set to be larger than the distance between the landing auxiliary electrode 14 and the nozzle of the inkjet head 11. In the present embodiment, the ink droplet charged to the positive (+) electrode is easily attracted to the charge removal electrode 15 that is the negative (−) electrode, and easily repels the recharged electrode 16 that is the positive (+) electrode. The distance between the landing auxiliary electrode 14 and the static elimination electrode 15 and the distance between the landing auxiliary electrode 14 and the recharging electrode 16 are as follows:
By making it larger than the distance between the landing auxiliary electrode 14 and the nozzle of the inkjet head 11, the influence of the static elimination electrode 15 and the recharging electrode 16 on the flight of the ink droplets ejected from the inkjet head 11 is suppressed and prevented. 14 can ensure the ink droplet suction effect.

As described above, according to the ink jet printer of this embodiment, the ink charging means charges the ink to a predetermined polarity, and the ink charging potential is set on the opposite side of the nozzle of the ink jet head 11 with the conveying belt 1 interposed therebetween. Since the landing auxiliary electrode 14 having a reverse polarity potential is disposed in a non-contact manner on the transport belt 1, the ink droplets fly toward the landing auxiliary electrode 14 due to electrostatic force. Therefore, the position of the landing auxiliary electrode 14 is changed. By setting appropriately, the ink droplet can be landed more actively at the target landing position, and the flight speed can be increased on the ink droplet, so that the time required for printing can be shortened. In addition, the neutralization electrode 15 for removing the charging of the conveyance belt 1 is disposed at a position separated from the landing auxiliary electrode 14 on the upstream side of the landing auxiliary electrode 14 in the printing medium conveyance direction. By removing the effect of the electric field of the belt 1 on the ink droplets, the ink droplets can be landed on the target landing position even more.

In addition, since the distance between the landing auxiliary electrode 14 and the static elimination electrode 15 is larger than the distance between the landing auxiliary electrode 14 and the nozzle of the inkjet head 11, the inkjet head 1.
The influence of the charge removal electrode 15 on the flight of ink droplets ejected from one nozzle can be suppressed and prevented.
In addition, by providing an insulating plane regulation body 13 that regulates the plane of the conveyance belt 1 and the print medium 2 between the landing auxiliary electrode 14 and the static elimination electrode 15, the landing auxiliary electrode 14 and the static elimination electrode 15 are provided. As a result, it is possible to ensure the insulation and secure the distance between the landing auxiliary electrode 14 and the static elimination electrode 15.

In addition, since the recharging electrode 16 that charges the conveyance belt 1 is provided at a position separated from the landing auxiliary electrode 14 on the downstream side of the landing auxiliary electrode 14 in the printing medium conveyance direction, the printing medium on which the ink droplets are discharged is provided. 2 can be reliably electrostatically adsorbed to the conveyor belt 1.
Further, the distance between the landing auxiliary electrode 14 and the recharging electrode 16 is made larger than the distance between the landing auxiliary electrode 14 and the nozzle of the inkjet head 11, thereby preventing the ink droplets ejected from the nozzle of the inkjet head 11 from flying. The influence of the recharging electrode 16 can be suppressed and prevented.

In addition, by providing an insulating plane regulating body 13 that regulates the plane of the transport belt 1 and the printing medium 2 between the landing auxiliary electrode 14 and the recharging electrode 16, the landing auxiliary electrode 14 and the recharging electrode 16 are disposed. As a result, the distance from the auxiliary landing electrode 14 and the recharging electrode 16 can be secured.
In addition, even if the polarity of the DC potential applied to the landing auxiliary electrode 14 and the inkjet head 11 is reversed from the setting in the above-described embodiment, the effect is the same.

The ink jet printer of the present invention is not only for electrostatically attracting and transporting the print medium 2 to the transport belt 1, but also for simply placing the print medium on the transport belt, or for applying the print medium to the transport belt by air suction. The present invention is applicable to any ink jet printer as long as the print medium is placed on the surface of the transport belt and transported, such as the one transported by suction. In the case where the conveyance belt is not positively charged, the effect of the ink jet printer of the present invention is not as remarkable as in the above embodiment, but the electric field of the electric charge due to the charge of the conveyance belt charged by removing the charge of the conveyance belt due to some cause is removed. It is possible to remove the action on the ink droplet and land the ink droplet on the target landing position.

1 is a front view illustrating a schematic configuration of an embodiment of an inkjet printer according to the present invention. It is explanatory drawing of the plane formation part of FIG. It is explanatory drawing of the plane control body and landing auxiliary electrode which oppose 1 row of nozzles among the plane formation parts of FIG. It is explanatory drawing which shows the relationship between a landing auxiliary electrode and an inkjet head.

Explanation of symbols

1 is a conveying belt, 2 is a printing medium, 3 is a driving roller, 4 is a driven roller, 7 is a charging roller,
8 is a DC power source, 9 is a pressure roller, 11 is an inkjet head, 12 is a plane forming portion, 13
Is a plane regulating body, 14 is an auxiliary landing electrode, 15 is a static elimination electrode, and 16 is a recharging electrode.

Claims (6)

In an ink jet printer that places a print medium on the surface of a conveyance belt and conveys the ink, and discharges ink droplets from the nozzles of an ink jet head onto the print medium to perform printing, an ink charging unit that charges ink to a predetermined polarity; A landing auxiliary electrode disposed in a non-contact manner on the opposite side of the nozzle of the ink jet head across the conveying belt and having a polarity opposite to the charging potential of the ink, and a printing medium conveying direction than the landing auxiliary electrode An ink jet printer comprising: a discharge electrode disposed upstream from the landing auxiliary electrode and a charge eliminating electrode for removing charge of the transport belt. 2. The ink jet printer according to claim 1, wherein a distance between the landing auxiliary electrode and the static elimination electrode is made larger than a distance between the landing auxiliary electrode and a nozzle of the ink jet head. The ink jet printer according to claim 1 or 2, wherein an insulating flat surface regulating member for restricting a flat surface of the transport belt and the print medium is interposed between the landing auxiliary electrode and the static elimination electrode. The recharging electrode for charging the conveyance belt is provided at a position separated from the landing auxiliary electrode on the downstream side in the printing medium conveyance direction from the landing auxiliary electrode. The inkjet printer as described. 5. The ink jet printer according to claim 4, wherein a distance between the landing auxiliary electrode and the recharging electrode is larger than a distance between the landing auxiliary electrode and a nozzle of the ink jet head. 6. The ink jet printer according to claim 4, wherein a plane regulation body that regulates a plane of the conveyance belt and the print medium is interposed between the landing auxiliary electrode and the recharging electrode.

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