JP2002046310A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein disturbance in an image at edge sections of a recording medium can be eliminated in the case where the image is formed by charged particles in a condition that the recording medium is electrostatically attracted to a conveyance means. SOLUTION: This image forming apparatus comprises a conveyance belt 20 that conveys a recording paper P in a condition that the recording paper P is electrostatically attracted to a conveyance face A, an ink supplying means 1 for forming an image on the recording face of the recording paper P by supplying charged ink particles toward the recording paper P, a charging means 4 that charges the conveyance belt 20 in the pole opposite to that of the ink particle and allows the recording paper P to be attracted to the conveyance belt 20 and a discharging brush 7 which is provided to a conveyance path between the ink supplying means 1 and the charging means 4 and reduces the overcharges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording surface of a recording medium by supplying ink particles to the recording medium to be conveyed.

[0002]

2. Description of the Related Art The prior art of such an image forming apparatus will be described with reference to the drawings. FIG. 3 shows a configuration example of a color inkjet printer. The recording paper P (corresponding to a recording medium) stacked in the magazine 80 is conveyed toward an ink supply unit 83 by a supply roller 81 and a timing roller pair 82. Then, the transport belt 88
A transporting means 93 for transporting the recording paper P along a predetermined transporting path by a plurality of transporting rollers 84, 85a, 85b, 85c; and cyan, magenta, The yellow ink cartridges 89C, 89M, and 89Y and the transport surface A of the recording paper P
A housing box 91 that houses the transporting means 93 with only the outside exposed is provided, and an exhaust fan 92 that is attached to a ventilation hole 91 a formed in a part of the housing box 91.

The transport belt 88 has a large number of through-holes. When the exhaust fan 92 is driven, the air in the storage box 91 is sucked and discharged to the outside. When the air in the storage box 91 is sucked, the rear side 88b of the transport belt 88 is moved from the front side 8b to the front side 8b.
The air 8a is sucked, and the recording paper P is sucked on the surface of the transport belt 88.

[0004]

However, when the recording paper P is greatly curled or the recording paper P is strong, it is difficult to bring the recording paper P into close contact with the transport surface of the transport belt 88. There are issues. Further, in the conventional ink jet printer, there is also a problem that the supply direction of the ink to the recording paper P is deviated to cause variation.

In order to solve such a problem, the present applicant has
Transport means for transporting the recording medium mounted on the transport surface, and ink supply means for forming an image on the recording surface of the recording medium by supplying charged ink particles toward the transported recording medium And a charging unit provided on the upstream side of a transport path of the ink supply unit, charging the transport unit to a polarity opposite to that of the ink particles, and electrostatically adsorbing the recording medium to the transport unit. Filed an application for an image forming device (printer device)
-14463).

According to this configuration, the recording medium is not electrostatically attracted to the conveyor belt (conveying means), so that no displacement or floating occurs. Further, the ink particles are supplied toward the recording medium, and the ink particles are charged and the transport belt that conveys the recording medium is also charged to the opposite polarity to the ink particles. Further, the recording surface of the recording medium electrostatically attracted to the transport belt is also charged to the opposite polarity to the ink particles by the dielectric polarization. This allows the ink particles to
It is supplied straight to the recording medium. However, when the recording medium is electrostatically attracted to the transport belt, it is necessary to increase the charge amount in order to surely attract the recording medium. Therefore, when an image is formed by supplying ink particles to a recording medium, there is a problem that the image is disturbed at the boundary between the recording medium and the conveyance belt (the edge of the recording medium). This is because the charge amount is different between the recording surface of the recording medium and the transport surface of the transport belt (the tendency is more evident when the charge amount is increased). It is because it is drawn to.

If the amount of charge when the recording medium is adsorbed is reduced, the image is not disturbed. However, in order to surely electrostatically adsorb a recording medium of various sizes or a recording medium having a curl habit, it is necessary to charge the recording medium. The amount has to be large. The present invention has been made in view of the above circumstances, and an object of the present invention is to form an image using an ink particle charged in a state where the recording medium is electrostatically attracted to a conveyance unit, and to form an image at an edge of the recording medium. An object of the present invention is to provide an image forming apparatus in which disturbance does not occur.

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention comprises a conveying means for conveying a recording medium in a state of being electrostatically attracted to a conveying surface, and a conveying means for conveying charged ink particles. An ink supply unit that forms an image on a recording surface of the recording medium by supplying the recording medium to the recording medium, and an ink supply unit that is provided upstream of a conveyance path of the ink supply unit, wherein the conveyance unit includes the ink particles. Is provided in a charging path for charging the recording medium electrostatically to the conveying means, and a conveying path between the ink supply means and the charging means, and removes excess charge by the charging means. And a static eliminator that performs the operation. The operation of the image forming apparatus having this configuration is as follows. First, a recording medium such as recording paper is conveyed while being mounted on a conveying surface of a conveying unit. The transport unit electrostatically attracts the recording medium by being charged by the charging unit. An ink supply unit is provided, and an image is formed on a recording surface of a recording medium by ink particles supplied from the ink supply unit. The ink particles are also charged, and are charged to a polarity opposite to that of the transport unit. The charging means is arranged on the upstream side of the transport path of the ink supply means, and the discharging path is provided on the transport path between the charging means and the ink supply means.

[0008] By this discharging means, it is possible to remove the excessive charge charged on the conveying means and the recording medium. Accordingly, when the recording medium is conveyed to the position of the ink supply unit, since the excess charge has been removed, the ink particles may be drawn toward the conveyance surface of the conveyance unit at the edge of the recording medium. Absent. As a result, it is possible to provide an image forming apparatus in which the image is not disturbed at the edge of the recording medium.

In a preferred embodiment of the present invention, the discharging means is a discharging brush in contact with or in proximity to the recording surface of the recording medium. Use of a charge elimination brush as a charge elimination means has a cost advantage. Since the disposition brush is disposed on the upstream side of the ink supply means, there is no possibility that ink particles adhere to the tip of the brush and become dirty.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating the configuration of an image forming apparatus, and FIG. 2 is a diagram illustrating the principle of dielectric polarization. <Configuration of Image Forming Apparatus> In FIG. 1, an image forming apparatus includes an ink supply unit 1 for forming a color image by supplying ink particles to a recording sheet P (corresponding to a recording medium). Transport means 2 for electrostatically attracting and transporting; recording paper supply means 3 for supplying recording paper P to ink supply means 1; charging means 4 for charging transport means 2; Cleaning means 5 for cleaning ink adhered to the transport surface of the means 2;
Ejecting unit 6 for ejecting recording paper P on which an image has been formed
And Further, on a transport path between the ink supply unit 1 and the charging unit 4, there is provided a discharging brush 7 functioning as a discharging unit. The ink supply means 1 is provided with ink cartridges 10C, 10M, and 10Y for discharging (one mode of supply) the cyan, magenta, and yellow ink particles in order from the upstream side along the transport path. Each of the ink cartridges 10C, 10M, 10Y has a supply port 11C, 11 for discharging ink particles.
M, 11Y are provided. Supply ports 11C, 11M,
From 11Y, + (positive) charged ink particles are ejected. A two-dimensional image can be formed on the recording paper P by transporting the recording paper P in the direction of the arrow S in FIG. 1 while forming an image one line at a time by each of the ink cartridges 10C, 10M, and 10Y.

The transport means 2 includes a transport belt 20 and transport rollers 21, 22, 23, and 24. The transport belt 20 is formed of a material that is easily charged, and mounts the recording paper P on the transport surface A facing the ink supply unit 1 in a state where the recording paper P is electrostatically attracted. The transport belt 20 is preferably one selected from the group consisting of a polyimide resin and a polyvinylidene fluoride resin.

The recording paper supply means 3 includes a magazine 30 for accommodating a plurality of recording papers P in a stacked state, and a supply roller 31 for supplying the recording papers P from the magazine 30 toward a transport path.
And a timing roller pair 32 for feeding the recording paper P toward the ink supply means 1 at an appropriate timing.

The charging means 4 includes a charging roller 4 made of conductive rubber.
0, a high-voltage transformer 41, and a polarization roller 42 (ground roller). The charging roller 40 and the polarization roller 42 are located at positions facing the transport roller 21.
The drive roller 21 has a high resistance, thereby facilitating charging of the transport belt 20. Polarizing roller 4
2 is grounded, thereby causing the recording paper P to generate dielectric polarization.

The cleaning means 5 cleans ink adhered to the surface of the transport belt 20 by the cleaning web 50. The cleaning means 5 includes an opposing roller 51 facing the transport roller 23, a supply roller 52, and a take-up roller 53. Have. The discharge unit 6 includes a discharge roller pair 60 that discharges the recording paper P on which an image is formed. The discharge roller pair 60 also functions as a fixing roller pair.

To ensure that the recording paper P is electrostatically attracted to the conveyor belt 20, the conveyor belt 20 is charged by the charging means 4. Because the recording paper P has various sizes and has a curl habit,
To ensure adsorption, it is necessary to give a considerable amount of charge. As described later, both the recording surface of the recording paper P and the transport surface A of the transport belt 20 are negatively charged, but the transport surface A of the transport belt 20 has a larger charge amount. Then, at the edge of the recording surface, the positively charged ink particles tend to be attracted to the more strongly charged one. Therefore, at the edge of the recording surface, the ink particles are not supplied straight, and this causes the formed image to be disturbed, resulting in deterioration of the image quality.

Therefore, in the present invention, the neutralizing brush 7 is used.
Are arranged to remove excess charges on the transport surface A and the recording surface. Thereby, disturbance of the image at the edge of the recording surface is eliminated. In addition, it was experimentally confirmed that there was no change in the attraction force between the recording paper P and the conveyance belt 20 even when the excess charge was removed. The neutralization brush 7 has fine metal fibers, amorphous fibers, carbon fibers, and the like provided at the tip thereof over the width direction of the transport belt 20. Excess charge can be removed by bringing metal fibers or the like into contact with or close to the transport surface A of the transport belt 20 and the recording surface of the recording paper P. Instead of the neutralizing brush 7, a non-contact neutralizing means for causing ions of opposite polarity to fly to a transport surface or the like may be employed, but the neutralizing brush 7 is advantageous in terms of cost. <Principle of Electrostatic Attraction and Supply of Coloring Material> Next, referring to FIG.
And the principle of supplying a color material to the device will be described. In the image forming apparatus according to the present invention, a mixture of the solvent and the ink particles 12 a ionized in opposite polarities is used as the coloring material 12. As a configuration for supplying the ink particles 12a toward the recording paper P, for example, ink is ejected and supplied, and various methods can be selected to control the traveling direction and speed of the ink. . For example, the ink can be continuously ejected and vibrated to form the ink into particles, or the ink particles 12a can be ejected in a droplet state as in the present embodiment.

A polarizing roller 42 is disposed so as to contact the recording surface of the recording paper P. The polarizing roller 42 is arranged so that the recording surface of the recording paper P has the opposite polarity to the ink particles 12a. Is dielectrically polarized. And charging means 13
(Power supply) means that the surface of the color material ejection unit 14 side is the ink particle 12
It is charged to the same polarity as a. Further, the transport belt 20 is charged by the charging roller 40 to have a polarity opposite to that of the ink particles 12a.

In this embodiment, the transport belt 20 and the recording surface of the recording paper P are negatively charged and the ink particles 12a are positively charged. However, the polarities may be reversed. <Operation of Image Forming Apparatus> Next, the operation of the image forming apparatus according to the present embodiment will be described. First, the recording paper P is supplied from the magazine 30 by the one-sheet supply roller 31. When it is confirmed that the recording paper P does not exist at the position of the ink supply means 1, the timing roller pair 32 is driven to send out the recording paper P toward the ink supply means 1. On the other hand, the transport belt 20 is circulated by transport rollers 21 to 24, and the transport surface of the transport belt 20 is charged by the charging unit 4. At a position immediately after the conveyance belt 20 is charged, the recording paper P is conveyed while being sandwiched between the conveyance roller 21 and the polarization roller 42.

Next, when the recording paper P is conveyed to the position of the neutralizing brush 7, excess charges on the recording surface of the recording paper P and the conveyance surface A of the conveyance belt 20 are removed. With the excess charge removed, the recording paper P is supplied to the ink supply unit 1.
And a desired image is formed on the recording surface. The recording paper P on which the image has been formed is separated from the transport surface A and discharged to the outside of the apparatus main body by a discharge roller pair. In order to easily separate the recording paper P from the transport surface A, another neutralization unit may be provided downstream of the ink supply unit 1. On the other hand, the transport belt 20 is driven to circulate and sent to the cleaning unit 5, and the ink adhered to the transport surface A is removed by the cleaning web 5.
Removed by 0.

<Another embodiment> (1) As a transporting means, instead of transporting by a transport belt,
The present invention can be applied to the case of conveyance by a drum (rotary body). (2) The recording medium is not limited to recording paper, but may be a film or the like. In the case of paper, it is preferable to subject the paper material to a surface treatment (forming an acrylic resin layer) so as to easily cause dielectric polarization. Further, a film made of a synthetic resin having a large relative dielectric constant such as an acrylic resin or a polyester resin may be used. (3) The present invention can be applied to a case where a monochrome image is formed instead of a color image as an image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus.

FIG. 2 illustrates the principle of dielectric polarization.

FIG. 3 is a diagram illustrating a configuration of an image forming apparatus according to the related art.

[Explanation of symbols]

 Reference Signs List A transport surface P recording paper 1 ink supply means 2 transport means 3 recording paper supply means 4 charging means 7 static elimination brush 20 transport belt 40 charging roller

Claims (2)

[Claims] A transporting means for transporting the recording medium in a state where the recording medium is electrostatically attracted to the transporting surface; and supplying the charged ink particles toward the recording medium to be transported, whereby the recording surface of the recording medium is transported. An ink supply unit for forming an image on the recording medium; and an ink supply unit provided upstream of a conveyance path of the ink supply unit, charging the conveyance unit with a polarity opposite to that of the ink particles, and electrostatically charging the recording medium with respect to the conveyance unit. An image forming apparatus comprising: a charging unit to be adsorbed; and a charge removing unit provided on a transport path between the ink supply unit and the charging unit, for removing excess charge by the charging unit. 2. The image forming apparatus according to claim 1, wherein the discharging unit is a discharging brush that contacts or approaches a recording surface of the recording medium.