JPH07121038A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the scattering of an image forming medium into space and irregularities in the array of an image and to maintain cleaning performance by installing a charger supplying a charge having a polarity opposite to that of the image forming medium to a transfer material carrying means and the rear of an transfer material after being separated from the transfer material carrying means. CONSTITUTION:For preventing the separated electrification and Paschen discharge of the transfer material 2 and the transfer material carrying means 4, a DC voltage source 21 connected to a recovering roller 31 is connected to a roller 5 to apply the positive potential of the polarity opposite to that of the image forming medium to the roller 5 and further the charger 13 supplying a positive charge having the polarity opposite to that of the image forming medium is installed in a position opposite to the roller 5. In other words, the positive charge having the polarity opposite to that of the image forming medium is supplied to the rear of the transfer material 2 after being separated from the transfer material carrying means 4, so that the charger 13 is installed in such a manner that a surface opposite to the surface of the transfer material 2 on which an unifixed image forming medium is stuck is turned to an opening, in a place just after the separation of the transfer material 2 from the transfer material carrying means 4.

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 having a transfer material conveying means for electrostatically adsorbing and transferring the transfer material, and when the transfer material is separated from the transfer material conveying means, the transfer material is transferred onto the transfer material. The present invention relates to a device configuration that prevents the formed unfixed image from being disturbed, and is particularly advantageous in reducing the size and cost of the device.

[0002]

2. Description of the Related Art A conventional image forming apparatus will be described below. An image forming apparatus using an electrophotographic system is an apparatus for forming an image of an image forming medium on the surface of a transfer material. The image forming process includes a sheet feeding process for feeding out an unformed transfer material, a developing / transferring process for developing an image of the image forming medium on the transfer material surface as an image, and a visualized image forming medium image for the transfer material. The fixing step includes a fixing step, a discharging step for discharging the transfer material after fixing, and a conveying device for conveying the transfer material between the steps.

With the above construction, it is necessary to separate the transfer material from the transfer device during the transfer of the transfer material from the transfer device to the fixing step. At that time, Paschen discharge occurs between the transfer device and the transfer material, and the image forming medium is scattered. Then, there is a problem that the recorded image is disturbed. As a method for preventing this Paschen discharge, there is a technique disclosed in Japanese Patent Laid-Open No. 63-83776.

In this prior art, a charger having a grounded roller at a position where the transfer material 2 is separated from the transfer material transporting means as an opposite electrode is provided to have the same polarity as the charge of the transfer material transporting means, that is, image formation. A charge having a polarity opposite to that of the medium is generated to eliminate the charge on the transfer material to reduce the electrostatic repulsive force between the image forming medium and the transfer material and suppress the generation of the Paschen discharge. Was.

[0005]

However, in the method described in this prior art, the charger is installed on the surface of the transfer material that is held by the image forming medium, and the charge generating portion of the charger is the image forming medium. Since it has a high voltage having a polarity opposite to that of the above, an electric field for attracting the image forming medium is generated in the charge generation portion even though the charge on the transfer material is removed by the charger. For this reason, even in this method, the image forming medium on the transfer material has a high rate of collecting dust, and even if the amount of scattered particles is small, the image forming medium is in the charge generation portion of the charger for a long time. However, there was a drawback that the performance of the charger itself deteriorated. Further, since the shield case of the charger is grounded, the charge removal is insufficient at the position upstream of the charge generation portion of the charger, and an electric field that separates the image forming medium from the transfer material is generated between the shield case and the transfer material. As a result, the image forming medium is scattered in the shield case portion located upstream of the charge generating portion, and the image forming medium is deposited on the shield case. In the long term, the image forming medium deposited on the shield case is generated. Was poured onto the transfer material 2 and disturbed the image remarkably.

Further, the transfer material is given a charge having a polarity opposite to that of the image forming medium by a charger having a roller as an opposite electrode. Therefore, even if a sufficient charge to neutralize the charge of the transfer material is transferred from the charger to the transfer material, there is a roller, which is an opposite electrode, on the back of the transfer material and has a polarity opposite to that of the image forming medium. The charge moves from the charger, through the transfer material and to the roller. As a result, the transfer material has an electric charge having a polarity opposite to that of the electric charge of the image forming medium. Further, at this time, the amount of the transfer material charged with a charge having a polarity opposite to that of the charge of the image forming medium by the charger having the roller as the opposite electrode is easily affected by the moisture content of the transfer material which changes depending on the humidity of the environment. If the moisture content of the material is low,
Since the surface resistance and the volume resistance of the transfer material are increased and the transfer material is easily charged, the potential of the transfer material cannot be stably controlled. Therefore, a method of controlling the corona current flowing to the transfer material conveying means by humidity is described, but this method leads to an increase in the cost of the apparatus.

Regarding the drawback of the charger being installed on the surface of the transfer material that is held by the image forming medium, Japanese Patent Application Laid-Open No. HEI 3 (1998)
It is conceivable to install a charger on the surface of the transfer material opposite to the surface held by the image forming medium, as in the method described in Japanese Patent Publication No. 231274. However, in this method, the corona charge supplied to the transfer material by the charger is from the downstream side of the position where the transfer material is separated from the transfer material conveying means, and the corona charge is to the downstream side of the separation position on the upstream side of the separation position. Although slightly smaller than the above, the image forming medium scattered to the portion of the transfer material conveying means that is not covered with the transfer material promotes clogging of the cleaning brush for cleaning the transfer material conveying means in the long term, and the cleaner. However, there is a problem that the surface of the transfer / conveyance belt is contaminated due to the early deterioration of the performance, and further contaminates the transfer material in contact with the transfer material conveying means.

The object of the present invention is to solve the above problems in the prior art, suppress the cost increase of the apparatus, effectively suppress the problems that the image forming medium is scattered in the space, and disturb the arrangement as an image, and achieve high quality. Another object of the present invention is to provide an image forming apparatus which is capable of maintaining a high cleaning performance of the cleaner of the transfer material conveying means, in addition to having a configuration capable of obtaining various images.

[0009]

In order to achieve the above object, the present invention provides a charger 13, which is a charge applying device for supplying a charge having a polarity opposite to that of an image forming medium, as shown in FIG.
Immediately after the position where the transfer material 2 and the transfer material conveying means 4 are separated, the transfer material 2 is installed on the surface opposite to the surface holding the unfixed image forming medium. A configuration is adopted in which the counter electrode of the charger 13 is not provided on the medium holding surface side, and the side surface of the transfer material 2 opposite to the surface holding the unfixed image forming medium and the transfer material transporting means 4 are provided.
At, in the contact surface side between the transfer material conveying means 4 and the transfer material 2, electric charges having a polarity opposite to that of the image forming medium are supplied. In addition to this, the roller 5 corresponding to the transfer material 2 separating position of the transfer material conveying means 4 is electrically insulated from the ground potential, and the roller 5
Further, a DC voltage source having a polarity opposite to that of the image forming medium connected to the cleaner 12 of the transfer material conveying means and having the same polarity as the electric charge held by the transfer material conveying means 4 is connected.

[0010]

In the method of the present invention, the charger 13 is positioned immediately after the transfer material 2 and the transfer material conveying means 4 are separated from each other and on the surface opposite to the surface of the transfer material 2 holding the unfixed image forming medium. Therefore, a charge having a polarity opposite to that of the image forming medium generated by the charger 13 is applied to the separation point between the transfer material 2 and the transfer material conveying means 4, and the transfer material 2 is charged separately.
Is immediately neutralized, or the transfer material 2 is appropriately charged with a polarity opposite to that of the image forming medium. As a result, the image forming medium and the transfer material 2 do not repel electrostatically, and the polarity of the charge of the image forming medium and the polarity of the charge of the charger 13 are opposite, and the charger 13 is installed in the image forming medium. Since the image forming medium on the transfer material 2 is attracted in the direction, it does not scatter after the separation point between the transfer material 2 and the transfer material conveying means. Furthermore, the transfer material 2 is neutralized by the charge, or the absolute value of the potential is appropriately suppressed, whereby the transfer material 2
Contacting the guide member 22, the transfer material 2 and the guide member 2
Since no spark discharge is generated between the transfer material 2 and the transfer material 2, a pattern of the branch-shaped or spot-shaped image forming medium does not occur on the transfer material 2, and the image forming medium on the transfer material 2 is not disturbed and image quality is improved. Is retained.

Further, since the charger 13 does not have a counter electrode for the transfer material 2, the charge is supplied to the transfer material 2 by the charge of the transfer material 2 itself. As a result, even if the charge amount of the transfer material 2 is different, the charge supply to the transfer material 2 is stopped when the potential of the transfer material 2 becomes close to zero, so that the excess charge is not supplied.

The charger 13 also supplies the electric charge to the transfer material conveying means and applies an appropriate electric charge to the transfer material conveying means and the residual image forming medium on the surface of the belt so that the transfer material conveying means and the residual image forming medium are separated from each other. Relax the adsorption force. As a result, the residual image forming medium on the transfer material conveying means is easily separated from the transfer material conveying means 4 by mechanical sweeping due to the rotation of the cleaner brush 30, and the cleaning performance is improved.

Further, the bias potential of the opposite polarity to the image forming medium applied to the roller 5 of the transfer material conveying means 4 causes a Coulomb force to act between the transfer material and the transfer material to move the transfer material separating position to the charger side. By moving the charger to bring it closer to the separation position, the effect of charging the transfer material by the charger is enhanced. In addition, the bias potential to the roller causes a Coulomb force to act between the transfer material and the image forming medium on the surface of the transfer material so as to bring the transfer material and the image forming medium into close contact with each other, until the transfer material and the transfer material conveying means are separated. It also prevents the movement of the image forming medium.

By applying the bias voltage to the roller 5 using the DC voltage source 21 connected to the cleaner 12, the cost and space required when a separate power source is prepared can be reduced.

Thus, the movement of the image forming medium at the time of separating the transfer material and the transfer material conveying means and the prevention of the electrification of the transfer material after the separation can be achieved without significantly increasing the cost and the space, and the image forming medium. Image forming apparatus capable of maintaining high cleaning performance of the cleaner of the transfer material transporting means because the attraction force between the transfer material transporting means and the residual image forming medium is alleviated at the same time as the scattering in the space of the image forming apparatus and the disturbance of the image arrangement are eliminated. Can be provided.

[0016]

【Example】

<< Embodiment 1 >> An embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a schematic view of an image forming apparatus using the transfer material conveying means of the present invention, in which 1 is a photoconductor, 2 is a transfer material, 3 is a paper feeding hopper, 4 is a transfer material conveying means, 5, 6,
7 is a drive roller or a driven roller, 8 is a transfer device, 9 is a fixing device, 10 is a paper discharge stacker, 11 is a reverse conveyance process,
12 is a cleaner of transfer material conveying means, 13 is a charger,
Reference numeral 14 is a photoconductor charging device, 15 is an exposure device, 16 is a developing device, 17 is a photoconductor cleaner, and 18 is a reverse conveyance path.
However, the photoreceptor 1 uses a negatively charged organic photoreceptor,
The developing method by the developing device 16 is a reversal developing method using a two-component developer, and the image forming medium has a negative charge.
The transfer device 8 is a corotron charger that generates a positive charge and controls the corona current value.
It is also possible to adopt a method of controlling the electric potential applied to. Further, the transfer material conveying means 4 is an endless belt having a volume resistance of 10 ¹⁰ Ω · cm to 10 ¹³ Ω · cm at room temperature and normal humidity and a thickness of 0.06 cm. These conditions are the same in the following examples.

The process of image formation and the process of transporting the transfer material 2 in this apparatus will be described in detail with reference to FIG. First, the surface of the photoconductor 1 is charged to about -500 V by the photoconductor charging device 14, and then the exposure device 15 is used.
By irradiating the desired image portion to be formed with the light, an electrostatic latent image closer to zero potential is formed as compared with the background portion not irradiated with the light. The image forming medium stored inside the developing device 16 is about -35 μC due to friction.
The image forming medium is attracted only to the electrostatic latent image by applying to the developing device 16 an electric potential that is charged to / g and is intermediate between the electric potential of the background portion and the electric potential of the electrostatic latent image portion. A visible image is formed on the body 1 by the image forming medium.

In response to the above-described image forming process on the photosensitive member 1, the transfer material 2 is fed from the paper feeding hopper 3 and conveyed to the transfer material conveying means 4. The transfer material conveying means 4 is attached so as to surround the roller 5 and the driven rollers 6 and 7,
A roller 5 corresponding to the transfer material separating position of the transfer material conveying means 4.
The transferred transfer material 2 is conveyed in accordance with the rotation of. Thereafter, the image formed by the image forming medium on the photoconductor 1 is transferred to the transfer material 2 in a state where the transfer material 2 is sandwiched between the transfer material conveying means 4 and the photoconductor 1 at a position corresponding to the transfer device 8. Further, the untransferred image forming medium remaining on the surface of the photoconductor 1 is removed by the photoconductor cleaner 16, and the next image forming step is started. On the other hand, the transfer material conveying means 4 further conveys the transfer material 2 and sends it to the fixing device 9. In the fixing device 9, the image formed by the unfixed image forming medium on the transfer material 2 is transferred to the transfer material 2.
Fixed to. After that, in the case of single-sided printing, the transfer material 2 is discharged to the discharge stacker 10 and the printing ends. In the double-sided printing, the transfer material 2 is reversed through the reversal conveyance step 11, the transfer material 2 is again delivered to the transfer material conveyance means 4 through the reversal conveyance path 18, and the above-mentioned transfer, fixing, and paper ejection steps are repeated to perform printing. finish.

In this image forming step, the contact is made with the transfer material 2 such as an area outside the area corresponding to the gap between the transfer material 2 and the transfer material 2 in the photoconductor 1 or an area in the depth direction perpendicular to the transfer direction of the transfer material 2. Since a small amount of the image forming medium existing in the non-transferred area is transferred to the transfer material conveying means 4, the cleaner 12 of the transfer material conveying means is provided. A bias cleaning method is used for the cleaner 12 of the transfer material conveying means of this embodiment, and the cleaning brush 30, the collecting roller 31,
An image is formed by the electric field generated between the brush 32 and the grounded driven roller 6 by applying a positive potential having a polarity opposite to that of the image forming medium having a negative charge from the DC voltage source 33 to the cleaning brush 30. Clean the forming medium by suction. Further, from the DC voltage source 21 to the cleaning brush 30
An electric potential higher than the electric potential applied to the collecting roller 31 is applied to the collecting roller 31, and the image forming medium collected by the cleaning brush 30 is transferred to the collecting roller 31 by the electric field generated by the potential difference. The image forming medium transferred by the blade 32 is scraped off. As a result, the surface of the collecting roller 31 is always cleaned. In this embodiment, the potential applied to the cleaning brush 30 is + 600V.
Before and after, the potential applied to the collecting roller 31 is around + 1100V. However, the potential difference between the cleaning brush 30 and the roller 6 and the cleaning brush 30 and the collecting roller 31
The potential difference between and is at least several hundreds of V, and the image forming medium can be transferred. The larger the potential difference, the stronger the Coulomb force applied to the image forming medium can be, and the cleaning performance can be further improved.

Further, in order to prevent the separation charging and Paschen discharge of the transfer material 2 and the transfer material conveying means 4, the collecting roller 31.
A DC voltage source 21 connected to the roller 5 is connected to the roller 5, a positive potential having a polarity opposite to that of the image forming medium is applied to the roller 5, and a positive charge having a polarity opposite to that of the image forming medium is applied to a position facing the roller 5. A charger 13 for supplying is installed.

The charger 13 comprises an ultrafine wire 41 and a shield case surrounding a part thereof, and at least a part of the shield case facilitates a part of the current from the ultrafine wire 41 to flow in or a current to flow out from the ultrafine wire 41. It has the function of an electrode. In FIG. 1 showing the present embodiment, a positive charge having a polarity opposite to that of the image forming medium is supplied to the back surface of the transfer material 2 after being separated from the transfer material conveying means 4,
Immediately after the transfer material 2 and the transfer material transporting means 4 are separated, the charger 13 is installed so that the opening faces the surface opposite to the surface of the transfer material 2 to which the unfixed image forming medium is attached. At this time, the transfer material conveying means 4 on the roller 5 and the charger 1 are arranged so that the transfer material 2 does not enter the opening of the charger 13.
There is a step of about 5 mm between it and 3. Transfer material 2
In order to make the charge supply to the transfer material 2 more effective, the shield case of the charger 13 is provided between the wire 41 of the charger 13 and the point where the transfer material 2 is separated from the transfer material conveying means 4.
Alternatively, it is desirable that it is not shielded by the transfer material conveying means 4 or the like.

Further, a constant current of +1 μA or more is applied to the charger 13 in this embodiment. However, according to the measurement by the inventors, the potential of the transfer material 2 after the transfer is minus several hundreds to minus several thousand volts, the current required for neutralizing the charge of the transfer material 2 is several tens of μA at maximum, and the environmental conditions and the printing density are reduced. The result was fluctuated by. Based on this measurement result, it is also possible to arbitrarily supply a maximum +1 mA supply current to the charger 13 at a constant current.

The charger 13 is made up of the ultrafine wire 41.
And the ground electrode is not installed on the surface side of the transfer material 2 to which the unfixed image forming medium adheres. This is because the transfer material 2 is negatively charged by the above-described separation charging, and the positive charge supplied from the charger 13 is transferred to the transfer material 2.
This is because the attraction to the back side of the transfer material 2 is utilized, and when the potential of the transfer material 2 approaches 0 V due to the charge supply, the force of attracting the positive charge supplied from the charger 13 weakens and the transfer material 2 is attracted to the transfer material 2. Since the charge supply amount is reduced, it has a self-control function that the potential of the transfer material 2 after the charge supply becomes a predetermined value regardless of the magnitude of the potential of the transfer material 2 after the separation.

The charger 13 prevents charging of the transfer material 2 immediately after the transfer material 2 is separated from the transfer material carrying means 4. In addition to this, the transfer material carrying means 4 is also provided.
A positive bias potential having a polarity opposite to that of the image forming medium applied to the roller 5 causes a Coulomb force to act between the transfer material 2 and the separation position between the transfer material 2 and the transfer material conveying means 4 to move to the fixing device 9 side. Then, the charger 13 and the separation position are brought closer to each other, and the effect of supplying the charge of the transfer material 2 by the charger 13 is enhanced. Further, the bias potential to the roller 5 causes a Coulomb force to act also between the transfer material 2 and the image forming medium on the surface of the transfer material 2 in order to bring the transfer material 2 and the image forming medium into close contact with each other.
It also prevents the image forming medium from moving when the transfer material conveying means 4 is separated.

The potential to be applied to the roller 5 depends on the relationship between the potential applied to the roller 5 obtained by the inventors and the amount of scattering of the image forming medium shown in FIG. The amount of divergence decreases as the above potential is increased from minus to plus, and becomes very slight at a potential of + 1000V or more. As a result, the transfer material transporting means 4 transfers the transfer material more than a case where a negative potential for neutralizing the positive charge held by the transfer material transporting means 4 is applied to the roller 5 in contact with the surface holding the positive charge. When a positive potential that further promotes the potential due to the positive charge held by the means 4 is applied, the amount of scattering of the image forming medium decreases. Further, in the present embodiment, when a positive or negative potential is applied to the roller 5, the actual measured value of the current flowing through the voltage source connected to the roller 5 is the current measured when the potential of the transfer material conveying means and the voltage source are zero potential. Therefore, there was no transfer of electric charge between the transfer material conveying means 4 and the roller 5. Therefore, in the present embodiment, there is no movement of the charges held by the transfer material conveying means 4, and even if a positive DC voltage source is connected, the potential held by the transfer material conveying means 4 is further increased, and The DC voltage is not simply transferred to the transfer material 2 without promoting the separate charging of the transfer material conveying means.
It acts as a Coulomb force on the overlying imaging medium.

As described above, the potential applied to the roller 5 is +
Since the amount of the image forming medium scattered from the transfer material 2 becomes extremely small at a potential of 1000 V or more, in this embodiment, the potential applied to the collecting roller 31 is set to around +1100 V to improve the cleaning ability of the cleaner 12. The DC voltage source 21 that supplies a high voltage while maintaining the high voltage is applied to the roller 5 so that the image forming medium has a very small amount of scattering.

Furthermore, in our measurements, the roller 5
When the bias potential was not applied to the transfer material 2, the separation position of the transfer material 2 from the transfer material transporting means 4 moved from the point A in FIG. 1 to the point B by applying the bias potential.

With these settings, the image forming medium on the transfer material 2 does not scatter after the separation point between the transfer material 2 and the transfer material conveying means. Further, when electric charges are supplied to the image forming medium or the transfer material 2, spark discharge does not occur between the transfer material 2 and the guide member 22 even when the transfer material 2 comes into contact with the guide member 22, and therefore, on the transfer material 2. No branching or spot-like pattern due to the image forming medium is generated, the disorder of the image array on the transfer material 2 is completely eliminated, and the image quality is maintained.

Further, in this embodiment, since the polarity of the charger 13 of the cleaner 12 of the transfer material conveying means is reversed,
It was feared that the belt cleaning performance would deteriorate.
However, according to the experiments by the present inventors, as compared with the case where no charge is supplied to the image forming medium remaining on the belt or the case where a negative charge is supplied, the positive charge is applied to the belt in an appropriate range. It has been found that better belt cleaning performance can be maintained by supplying the remaining image forming medium. The reason for this is that the residual image forming medium and the transfer material transporting means 4 are more than the coulomb force between the cleaner 12 of the transfer material transporting means and the residual image forming medium is weakened by imparting a slight reverse characteristic charge to the residual image forming medium. This is because the effect of weakening the adsorption force of is generated.

In the present invention, the amount of electric charge generated from the charger 13 that flows into the roller 5 is limited by the opening state of the shield plate 23 installed in the opening of the charger 13, and the cleaner of the transfer material conveying means is limited. The cleaning performance of No. 12 is maintained in a good state.

In this embodiment, as shown in the configuration diagram of the transfer material 2 in the vicinity of the separation position in the present invention shown in FIG. 3, the height of the shield plate of the charger 13 is 10 mm from the bottom surface and the upper surface of the charger 13 is the same. Opening width (dimension C in Fig. 6) is 5mm
Is. The charge applied to the residual image forming medium is 5 to 10 μA in terms of the current flowing into the roller 5. However, this width C is usually set in the range of 1 to 18 mm, though it varies depending on the shape of the charger 13 and the input current.
Further, if the charge applied to the residual image forming medium is 0.5 to 20 μA in terms of the current flowing into the roller 5, good cleaning performance can be obtained.

With the above structure, it is possible to prevent the image forming medium from scattering, which causes image deterioration, until the transfer material 2 transferred to the image forming medium passes through the fixing device 9.
It is possible to provide an image forming apparatus that does not have a discharge pattern, does not significantly disturb the image even after long-term use, and can obtain a high-quality image without increasing the cost. At the same time, the cleaning performance of the cleaner 12 of the transfer material conveying means is always maintained. Can be kept in good condition.

Further, the charger 13 described in this embodiment is used.
By partially insulating the shield surface on the wire 41 side that generates the electric charge and the shielding plate 23, the electric charge supply effect is enhanced, and the electric charge from the charger 13 flowing into the roller 5 is suppressed, and the transfer material conveying means is provided. It is also possible to maintain good cleaning performance of the cleaner 12.

<Embodiment 2> Another embodiment of the present invention will be described below with reference to the configuration diagram in the vicinity of the separation position B of the transfer material 2 in FIG.

In the present embodiment, the charge supplied to the transfer material 2 by the charger 13 is separated from the separating position B and the charger 13 is supplied.
When supplied close to the current supply position, the charge of the transfer material 2 is not neutralized in the gap from the separation position B to the current supply position, and the current is prevented from being scattered in the gap. In order to keep the cleaning performance of the cleaner 12 good, the inclined plate 19 grounded in the same configuration as in the first embodiment is installed near the roller 5 in order to keep the cleaning performance good. Further, the electric charge is supplied to the image forming medium remaining on the transfer material conveying means by the opening between the inclined plate 19 and the shield plate 23.

When the positive bias potential is applied to the roller 5, the inclined plate 19 suppresses the scattering of the image forming medium up to the region where the effect of the positive bias potential extends to the transfer material 2. Since a strong positive electric field is formed around 5, the current of the charger 13, which is a positive current, is hindered by this electric field and is near the separation position B,
This is to prevent the positive electric field of the roller 5 from reaching the region where the effect of the positive bias potential reaches, and the positive electric field of the roller 5 is formed only between the inclined plate 19 and the charger 13 side from the inclined plate 19. The positive electric field is shielded, and a current path for supplying a current to the vicinity of the separation position B is secured.
As a result, the gap between the region where the positive bias potential of the roller 5 affects the transfer material 2 and the region where the effect of the current affects is eliminated, and the scattering of the image forming medium is suppressed in the entire region. However, at this time, when the present inventors continuously operate the image forming apparatus, the paper dust spilled from the transfer material 2 is accumulated on the upper surface of the inclined plate 19, and as a result, the transfer material 2 which is initially set in a good condition is transferred. I faced a problem that the current and the current supplied to the residual image forming medium on the transfer material transporting means 4 are disturbed. Due to this adverse effect, the performance of preventing the soaring of the image forming medium and the cleaning performance of the cleaner 12, which were good in the initial stage, decrease as the printing amount increases. Therefore, as shown in FIG. 4, with the insulating layer 20 covering the inclined plate 19 with an insulating material similar to paper powder, the electric current to the transfer material 2 and the residual image forming medium on the transfer material conveying means 4 are changed. The current supplied was set so that it would not be adversely affected by the accumulation of paper powder.

Further, in this embodiment, the gap D between the shield plate 23 and the inclined plate 19 is set to 3 mm to suppress the electric charge from the charger 13 flowing into the roller 5 and to improve the cleaning performance of the cleaner 12 of the transfer material conveying means. It is adjusted to hold it well. However, this gap width is usually set in the range of 1 to 10 mm, though it varies depending on the shape of the charger 13, the input current or the length of the inclined plate 19.

In the present configuration, as with all the effects described in the first embodiment, the scattering of the image forming medium that causes image deterioration occurs until the transfer material 2 transferred onto the image forming medium passes through the fixing device 9. It is possible to provide an image forming apparatus capable of preventing the occurrence of electric discharge, having no discharge pattern, and not significantly disturbing the image even when it is used for a long period of time, and at the same time, the cleaning performance of the cleaner 12 of the transfer material conveying means is always good. Can be kept in a good state.

<Embodiment 3> Another embodiment of the present invention will be described below with reference to FIGS. 5, 6, 7 and 8. FIG. 5 is a configuration diagram in the vicinity of the separation position B of the transfer material 2 of this embodiment, FIG. 6 is a schematic diagram for explaining the result of computer simulation of the electric field distribution of this configuration, and FIGS.
FIG. 6 is a configuration diagram in the vicinity of a separation position B of the transfer material 2 in another configuration of this embodiment.

The present embodiment prevents the phenomenon that the current of the charger 13 cannot reach the vicinity of the separating position B due to the influence of the positive electric field around the roller 5 shown in the second embodiment, and the current is separated from the separating position B. It shows another method for securing a current path to be supplied to.

In this embodiment, in order to prevent the above-mentioned phenomenon, the transfer material 2 is located below the transfer material transfer path in FIG. 5 and in the vicinity of the separation point between the transfer material 2 and the transfer material transfer means 4.
The potential applying member 25 is installed, and the DC voltage source 21 connected to the roller 5 is connected to this to apply a positive potential. In the present embodiment, the potential applying member 25 is used by electrically separating a part of the shield case of the charger 13.

In the present method, the positive potential of the potential applying member 25 is determined by directing the current supplied to the potential applying member 25 out of the current supplied from the ultrafine wire 41 of the charger 13 toward the transfer material 2. Although it has the effect of increasing the amount of current itself supplied to 2, the effect is basically achieved most efficiently in the configuration in which the shield of the charger 13 is not provided at the position of the potential applying member 25. In addition to the above, the present method has a peculiar effect that appears in the configuration of the present invention in which the potential of the same polarity as that of the charger 13 is applied to the roller 5 at a position close to the charger 13. That is, according to the schematic explanatory view of the result of the computer simulation of the electric field distribution of this configuration shown in FIG.
When a potential is not applied to 5, the electric field generated by the ultrafine wire 41 and the electric field generated by the roller 5 interfere with each other, and the electric field causes a barrier on the path for the current of the charger 13 to reach the vicinity of the separation position B. When the potential is applied to the potential applying member 25, the electric field generated by the potential applying member 25 eliminates the electric field barrier due to the electric field, and the current of the charger 13 is near the separation position B. A route to reach is secured.

As a method of applying a positive potential to the potential applying member 25, a DC voltage source 21 is applied to the potential applying member 25 as shown in the configuration diagram of the transfer material 2 near the separation position B shown in FIGS. Instead of connecting, the potential applying member 25 is grounded via a constant voltage element 27 as shown in FIG.
Alternatively, as shown in FIG. 8, the constant voltage element 27 is provided by grounding the resistor element 28 or by causing positive charges to flow from the ultrafine wire 41 of the charger 13 to the potential applying member 25.
Alternatively, it is possible to adopt a configuration in which a positive potential is induced in the resistance element 28. Further, as shown in FIG. 8, the potential application to the roller 5 may be performed by using the resistance element 28 as in the case of the potential application member 25. Although not shown, the resistance element 28 is the constant voltage element 27. May be. In adopting this configuration, the bias cleaner system is not used as the cleaner 12, and the DC voltage source 2 to be applied to the roller 5 is not used.
When there is no 1, there is no need to separately provide a DC voltage source, so the cost does not increase so much.

By using the above-described structure, the amount of the image forming medium scattered from the transfer material 2 can be reduced without increasing the cost, as in the second embodiment.
It is possible to provide an image forming apparatus that can obtain a high-quality image without significantly disturbing the image even if it is used for a long period of time, and at the same time, it is possible to always keep the cleaning performance of the cleaner 12 of the transfer material conveying means in a good state.

<Embodiment 4> This embodiment shows another embodiment of the above-mentioned Embodiment 3, and the potential in Embodiment 3 is changed as shown in the configuration diagram of the transfer material 2 near the separating position B shown in FIG. Instead of the applying member 25, the insulating shield member 29 is installed at a position close to the roller 5.

In this embodiment, positive charge is initially flowed from the ultrafine wire 41 of the charger 13 into the insulating shield member 29, and the insulating shield member 29 is positively charged. The positive potential generated in the conductive shield member 29 is the same as that in the above-mentioned embodiment.
The electric current of the charger 13 due to the interference between the electric field generated by 1 and the electric field generated by the roller 5 is
The barrier for the electric field on the path for reaching the vicinity of is removed, and the path for the current of the charger 13 to reach the vicinity of the separation position B is secured. In the insulating shield member 29, the insulating shield member 29
In order to regulate the positive potential generated in the
It is desirable that the insulating shield member 29 is grounded in the range of 00 MΩ, and 10 MΩ in this embodiment.
The thing of the degree is used.

Further, in this embodiment, when the image forming apparatus is continuously operated, the transfer material 2 is transferred to a portion where the shield case cross section is shown as a bottom surface in FIG. 9 and a side surface portion of the shield case cross section adjacent to the transfer material conveying means 4. Paper dust of
As a result, in order to deal with the phenomenon that the current to the transfer material 2 or the current supplied to the residual image forming medium on the transfer material conveying means 4 fluctuates over time, the bottom and side surfaces of the shield case are insulated from the beginning. It is constituted by the member 39, and in this state, the current to the transfer material 2 and the current to be supplied to the residual image forming medium on the transfer material conveying means 4 are set to eliminate the adverse effect due to the accumulation of paper dust. At this time, the transfer material conveying means 4
Since the paper dust does not accumulate on the side surface portion of the cross section of the shield case that hits the rear side of the ultrafine wire 41 when viewed from the direction of, the conductive shield member 38 for inducing corona discharge with the ultrafine wire 41 is not present. Has been installed.

With the above configuration, a current path for supplying a current to the vicinity of the position where the transfer material 2 is separated from the transfer material conveying means 4 can be secured, and the transfer material 2 can be transferred to the transfer material 2 over time due to the accumulation of paper powder during continuous operation. It was possible to prevent changes in the electric current and the electric current supplied to the residual image forming medium on the transfer material conveying means 4.

Further, in this embodiment, the insulating shield member 2 is used.
Since the fact that 9 is positively charged is used, it is necessary to consider the following items. That is, as shown in the schematic diagram showing the phenomenon in the embodiment of the present invention shown in FIG.
Is conveyed in the direction of arrow a2, the Coulomb force generated between the negative charge of the image forming medium and the positive charge of the insulating shield member 29 at the end G of the transfer material 2 orthogonal to the conveying direction. Indicates not only the thickness direction of the transfer material 2 but also the arrow a
Insulating shield member 29 from the image forming medium shown in FIG.
Work along the lines of electric force to. Therefore, when the image forming medium is transferred to a position extremely close to the end G, the force along the direction of the arrow a3 is stronger than the force acting in the thickness direction of the transfer material 2, and the image forming medium is insulated. There is a case where it scatters on the sex shield member 29. In this case, for example, when the transfer material 2 having a wide width is used after the transfer material 2 having a narrow width is continuously used, the insulating shield member 29 contaminated by the image forming medium scattered when the transfer material 2 having a narrow width is transported. There is a problem that the transfer material 2 having a wide width passes over and the transfer material 2 is contaminated. With respect to this problem, in the present embodiment, a method of reducing the force along the line of electric force to the insulating shield member 29 is used to increase the distance between the transfer material 2 and the insulating shield member 29. That is, as shown in the schematic configuration diagram of the insulating shield member 29 shown in FIG. 11, a beam structure member 61 is provided on the surface of the transfer material 2 in contact with the insulating shield member 29 using the same material as the insulating shield member 29. There is. As a result, in the present embodiment, the distance between the end G of the transfer material 2 and the insulating shield member 29 is increased, so that the electric field in the direction of the arrow a3 is reduced, and the scattering of the image forming medium on the insulating shield member 29 is reduced. Then
Even if the wide transfer material 2 is used after the narrow transfer material 2 is continuously used, the transfer material 2 is not contaminated.
In addition, this configuration is similar to the potential applying member 25 shown in the above embodiment.
The same effect can be obtained when used for.

<Embodiment 5> FIG. 12 is a schematic view of a transfer material separating portion in the transfer material conveying means of the present invention, in which the bottom surface and the side surface of the shield case are the insulating shield member 39 and the ultrafine wire 41. The conductive shield member 38 for inducing corona discharge is grounded between and, and the resistance is set to 10 MΩ so as to contact the conductive shield member 38.
A charger 13 having a configuration in which an insulating shield member 29 having a beam structure member 61 is arranged immediately below a transfer path of the transfer material 2 is used, and a DC voltage connected to a recovery roller 31 of a cleaner 12 is used as a roller 5. The source 21 has a configuration in which a positive potential is applied.

In the above structure, the electric field barrier on the path for the electric current of the charger 13 generated by the interference of the electric field by the ultrafine wire 41 and the electric field by the roller 5 to reach the vicinity of the separation position B is eliminated, and the charger is eliminated. A path for the current of 13 to reach the vicinity of the separation position B is secured, and the current and transfer to the transfer material 2 over time due to the accumulation of paper powder from the transfer material 2 which occurs during continuous operation of the image forming apparatus. The insulating shield member 29 for preventing the fluctuation of the supply current to the residual image forming medium on the material conveying means 4 is provided.
Prevents the image forming medium from scattering from the end portion of the transfer material 2 to the insulating shield member 29 due to being positively charged.

In the present embodiment, in addition to the above-mentioned structure, as shown in FIG. 12, the contact surface of the pre-fixing guide 22 for guiding the transfer material 2 from the transfer material conveying means 4 to the fixing device 9 with the transfer material 2 is grounded. Similarly to the case of the insulating shield member 29, the insulating member 47 having a beam structure in which the resistance is regulated to about 10 MΩ.
To prevent the image forming medium from scattering from the end portion of the transfer material 2 to the insulating member 47. The fixing device 9 uses heat, and the insulating member 47 preferably has heat resistance, and is made of, for example, a fluorine resin, a PPS resin, a ceramic material, a glass material mixed member, or a glass material.

Further, as shown in FIG. 12, when the transfer material 2 is conveyed from the transfer material conveying means 4 to the fixing device 9, there are metal structural members 43 and 44 on the transfer material 2,
Image charges of the image forming medium on the transfer material 2 are generated in the structural members 43 and 44, and the image forming medium is transferred to the structural member 4.
May be led to 3,44. To prevent this,
It is desirable to reduce the Coulomb force generated in the image forming medium on the transfer material 2 by covering the surfaces of the structural members 43 and 44 with the insulating member 48.

In the above-mentioned structure, it is possible to prevent the image forming medium from scattering and scattering until the transfer material 2 transferred onto the image forming medium passes through the fixing device 9.
An image forming apparatus that can obtain a high quality image can be provided.

[0056]

According to the present invention described above, at the position facing the roller at the transfer material separating position of the transfer material conveying means,
A charger is provided to supply a charge having a polarity opposite to that of the image forming medium to the back surface of the transfer material after separation from the transfer material conveying means and the transfer material conveying means to give an electric charge to the transfer material and charge the transfer material after separation. And improve the cleaner performance of the transfer material transporting means, and apply a bias potential having a polarity opposite to that of the image forming medium to the roller of the transfer material transporting means by using a DC voltage source connected to the cleaner of the transfer material transporting means. The separation position of the transfer material is closer to the charger to enhance the charge imparting effect on the transfer material by the charger, and a Coulomb force is also generated between the roller and the image forming medium on the surface of the transfer material by the bias potential. Since the transfer material and the image forming medium are brought into close contact with each other, there is no long-term performance deterioration of the charger itself, and the scattering and movement of the image forming medium at the time of separating the transfer material and the transfer material conveying means are prevented, An image forming apparatus capable of preventing generation of a discharge pattern of an image forming medium on a transfer material after separation, maintaining high cleaning performance of a transfer material conveying means cleaner, and providing a high-quality image with a relatively inexpensive structure The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus using a transfer material conveying unit of the present invention.

FIG. 2 is a diagram showing a relationship between an electric potential applied to a roller and a scattering amount of an image forming medium.

FIG. 3 is a configuration diagram in the vicinity of a separation position of a transfer material according to the present invention.

FIG. 4 is a configuration diagram in the vicinity of a separation position of a transfer material showing another embodiment of the present invention.

FIG. 5 is a configuration diagram in the vicinity of a separation position of a transfer material showing another embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating an effect in one embodiment of the present invention.

FIG. 7 is a configuration diagram of a transfer material in the vicinity of a separation position according to another embodiment of the present invention.

FIG. 8 is a configuration diagram of a transfer material in the vicinity of a separation position according to another embodiment of the present invention.

FIG. 9 is a configuration diagram in the vicinity of a separation position of a transfer material showing another embodiment of the present invention.

FIG. 10 is a schematic diagram showing a phenomenon in one example of the present invention.

FIG. 11 is a schematic configuration diagram of an insulating shield member according to an embodiment of the present invention.

FIG. 12 is a schematic view of a transfer material separating portion in the transfer material conveying means of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Transfer material, 3 ... Paper feeding hopper, 4 ... Transfer material conveying means, 5, 6, 7 ... Driving roller, Driven roller, 8 ...
Transfer device, 9 ... Fixing device, 10 ... Paper stacker, 11 ...
Inversion conveyance step, 12 ... Cleaner of transfer material conveying means, 13
... charger, precharger, 14 ... photoconductor charging device, 15 ... exposure device, 16 ... developing device, 17 ... photoconductor cleaner, 18 ... reversing conveyance path, 19 ... inclined plate, 20 ... insulating layer, 21 ... DC voltage source , 22 ... Pre-fixing guide, 23 ... Shielding plate, 25 ... Potential applying member, 26 ... Resistor element, 27 ... Constant voltage element, 28 ... Resistor element, 29 ... Insulation shield member,
30 ... Cleaning brush, 31 ... Collection roller, 32 ...
Blade, 33 ... DC voltage source, 38 ... Conductive shield member, 39 ... Insulation shield member, 41 ... Extra fine wire, 4
3, 44 ... Metal structural member, 47, 48 ... Insulating member, 61
... Beam structural members.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G03G 21/10 (72) Inventor Teruaki Mitsuya 7-1 Omika-cho, Hitachi-shi, Ibaraki Stock ceremony Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor, Kazuto Masuda, 7-1, 1-1, Omika-cho, Hitachi City, Ibaraki, Ltd. Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor, Takao Umeda 2-chome, Otemachi, Chiyoda-ku, Tokyo No. 2 Nitto Koki Co., Ltd. (72) Inventor Masaho Anzai 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Nitate Koki Co., Ltd. (72) Inventor Natsuki Kuribayashi Otemachi, Chiyoda-ku, Tokyo 2-6-2 Nititsu Koki Co., Ltd. (72) Inventor Masato Miwa 2-6-2 Otemachi Ochimachi, Chiyoda-ku, Tokyo Inside Nitate Koki Co., Ltd. (72) Inventor Takashi Suzuki Chiyoda-ku, Otemachi chome No. 6 No. 2 Date Tatsuko machine within the Corporation, Kyoto (72) inventor Yasuo Kikuchi Otemachi, Chiyoda-ku, Tokyo chome No. 6 No. 2 Date Tatsuko machine within Co., Ltd.

Claims (16)

[Claims] 1. A transfer material transporting means for electrostatically attracting and transporting a transfer material provided with an unfixed image forming medium, and an unfixed image forming medium adhered on the transfer material transporting means. A cleaning mechanism configured to be swept by a member to which a voltage having a polarity opposite to that of the charge held by the image forming medium is applied, and a charge held by the image forming medium on the transfer material on a supporting member at the downstream end of the transfer material conveying means. The image forming medium is provided with a mechanism for applying a voltage of opposite polarity, adjacent to a further downstream side of the support member at the downstream end of the transfer material conveying means, and at least one of the transfer material and the transfer material conveying means. An image forming apparatus configured to install a charge applying device that applies a charge having a polarity opposite to that of a held charge, wherein a voltage applied to a support member at a downstream end of the transfer material transporting means and a cleaning mechanism of the transfer material transporting means. The voltage applied to An image forming apparatus characterized by comprising using a common DC voltage source. 2. The method according to claim 1, wherein the transfer material transporting means is provided at a downstream end thereof and is adjacent to a downstream side of a support member for applying a voltage having a polarity opposite to a charge held by the image forming medium on the transfer material, A charge applying device is installed at a position on the back surface of the surface where the image forming medium is not fixed and is held on the transfer material, and the image forming is performed on at least one of the transfer material and the transfer material conveying means by the charge applying device. An image forming apparatus characterized in that a charge having a polarity opposite to that of a charge held by a medium is applied. 3. The charge applying device according to claim 1, wherein the charge applying device applies a charge having a polarity opposite to that of the charge held by the image forming medium to at least a separation point between the transfer material and the transfer material conveying means. Image forming apparatus. 4. The corotron according to claim 1, wherein the charge applying device comprises a wire and a shield case surrounding a part of the wire, and applies a DC voltage having a polarity opposite to that of the charge held by the image forming medium to the wire. A charging device, which has an opening on the surface facing the supporting member of the transfer material conveying means corresponding to the position where the transfer material separates from the transfer material conveying means, and on the back side of the transfer material as seen from the charge applying device, An image forming apparatus comprising no grounded electrode facing the charge applying device. 5. A shield plate made of a conductor or a dielectric material is installed at an intermediate position between the charge applying device and the transfer material conveying means according to any one of claims 1 to 4. An image forming apparatus characterized by using the charge applying device for limiting to a specified value. 6. The image forming method according to claim 1, wherein a potential having a polarity opposite to that of the image forming medium on the transfer material is applied to the supporting member corresponding to a position where the transfer material is separated from the transfer material conveying means. In the apparatus, it is preferable to use the charge applying device having a member for suppressing an electric field generated by a potential having a polarity opposite to that of the image forming medium near a separation position of the transfer material to a supporting member side of the transfer material conveying unit. A characteristic image forming apparatus. 7. The conductive member according to claim 6, wherein a member for suppressing an electric field having a potential having a polarity opposite to that of the image forming medium in the vicinity of the separation position of the transfer material to the supporting member side of the transfer material conveying means is grounded. A metal plate in which the surface of the body or the conductor is covered with an insulator, the upstream end of the metal plate in the transfer material transport direction is close to the separation position of the transfer material,
Further, the image forming apparatus is characterized in that the flat surface of the metal plate is installed so as to be inclined along the surface of the transfer material conveying means. 8. An image forming apparatus according to claim 1, wherein the transfer member is provided with a potential opposite in polarity to that of the image forming medium on the transfer material to a supporting member corresponding to a position where the transfer material is separated from the transfer material conveying means. An image forming apparatus using the charge applying device in which a member for applying a voltage having the same polarity as the supporting member of the transfer material conveying means is disposed adjacent to a separation point of the transfer material. 9. The charge applying device according to claim 8,
An image characterized in that the means for applying a voltage having the same polarity as that of the supporting member to the member arranged adjacent to the separation point of the transfer material is a DC voltage source common to the supporting member of the transfer material conveying means. Forming equipment. 10. The charge applying device according to claim 8, wherein the means for applying a voltage having the same polarity as that of the supporting member of the transfer material conveying means to the member arranged adjacent to the separation point of the transfer material, A constant voltage element or a resistance element is connected to a member adjacent to the supporting member of the transfer material conveying means, and a charge having the same polarity as that of the supporting member of the transfer material conveying means is supplied to the member to which the constant voltage element or the resistance element is connected. An image forming apparatus characterized by inducing a voltage by performing. 11. The charge applying device according to claim 8, wherein at least a part of a member arranged adjacent to a separation point of the transfer material is an insulator, and the transfer material conveying means is provided on the insulator. The image forming apparatus is characterized in that an electric charge having the same polarity as that of the supporting member is applied and charged to induce a voltage having the same polarity as that of the supporting member of the transfer material conveying means. 12. The charge applying device according to claim 11, wherein the resistance of the insulator used for the member disposed adjacent to the separation point of the transfer material is defined in the range of 1 MΩ to 100 MΩ. Image forming apparatus. 13. The charge applying device according to claim 8, wherein the surface of the member disposed adjacent to the separation point of the transfer material is installed at a position in contact with the transferred transfer material, An image forming apparatus, wherein a contact surface of a member arranged adjacent to the separation point with the transfer material has a beam structure. 14. The charge applying device according to claim 1, wherein the charge applying device comprises a wire and a shield case surrounding a part of the wire, and a surface facing a supporting member corresponding to a position where the transfer material is separated from the transfer material conveying means. A corotron charger that has an opening in the wire and applies a DC voltage having a polarity opposite to that of the electric charge held by the image forming medium to the wire, and has an insulating property that penetrates into the inside of the shield case from at least the bottom surface of the shield case or the opening. An image forming apparatus, characterized in that the shield surface on which the dust is accumulated is made of an insulator. 15. A transfer material transport path for guiding the transfer material from the transfer material transporting means to a means for fixing an unfixed image forming medium on the transfer material according to any one of claims 1 to 14, An image forming apparatus, wherein a contact surface of a member contacting with the member has a beam structure. 16. A transfer material conveying path for guiding the transfer material from the transfer material conveying means to a means for fixing an unfixed image forming medium on the transfer material according to claim 1, An image forming apparatus characterized in that the surface of a metallic member located on the holding surface side of an unfixed image forming medium is covered with an insulator.