JPS606839Y2 - Transfer paper conveyance device in electronic copying machines, etc. - Google Patents

Description

[Detailed Description of the Invention] The present invention includes an endless belt of a conductive material disposed adjacent to at least one image carrier, and at least two rollers around which the endless belt is wound. The present invention relates to a transfer paper conveying device in an electronic copying machine or the like, which feeds a transfer paper to the image carrier and transfers a toner image formed on the image carrier to the transfer paper.

Transfer paper conveying devices of the above type used in electronic copying machines or electrostatic recording devices are known, and in this type of device,
An endless belt is passed through the endless belt, whereby the transfer paper is electrostatically attracted to the endless belt and the transfer paper is conveyed.

However, with this conventional configuration, when the transfer paper attracted by the endless belt passes through the region of the roller, there is a risk that the transfer paper may be lifted off the surface of the endless belt.

If the transfer paper lifts off the surface of the belt in this way, not only will it cause errors in conveyance of the transfer paper, but the timing of feeding the transfer paper to the image carrier will be shifted, and there is a risk that the image will not be transferred to the designated position on the transfer paper. Also occurs.

In particular, in multicolor electrophotographic devices, images are sequentially transferred from multiple image carriers to transfer paper, so if the paper feeding timing of the transfer paper is shifted, each image transferred to the transfer paper may be misaligned, resulting in sharpness. This causes the inconvenience of not being able to obtain a clear image.

In order to eliminate this drawback, a conventional endless belt is provided with a guide in the area where it is turned by the roller, and this guide prevents the transfer paper from floating.
It was difficult to completely prevent the transfer paper from floating with only this guide.

The present invention aims to provide a transfer paper conveying device that eliminates the above-mentioned conventional drawbacks, and embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a multicolor electronic copying machine to which the present invention is applied, and in order to understand the present invention, the outline of the copying machine shown in FIG. 1 will first be briefly explained.

The copying machine shown in FIG. 1 has a photosensitive drum la.

Three image carriers configured as 1b, 1c are arranged parallel to each other.

When the copying operation is started and each photosensitive drum 1a, 1b, lc begins to rotate in the direction of the arrow, each drum la, lb, l
Chargers 2a, 2bt 2c arranged around c
The surface of each drum is charged.

On the other hand, when the document table 3 moves to the right at the same speed as the circumferential speed of the drum, the document 4 placed on the document table 3 is illuminated by an illumination device (not shown), and the illumination light is reflected by a mirror. 5,6
．． The charged portion of each drum is irradiated with light from lenses 9 7a to 7c, 8a to 8c and color separation filters 10a, 10b, and 10c through an optical system.

As a result, a color separation latent image is formed on the surface of each drum, and these latent images are transferred to a developer roller disposed around each drum, such as a magnetic brush developing device 11a, llb as shown in the figure.
The image is visualized (toner image) by 11C.

In this case, the first developing device 11a stores yellow toner, the second developing device 11b stores magenta toner, and the third developing device 11c stores cyan toner. A yellow toner image, a magenta toner image, and a cyan toner image are respectively formed.

Each of the above-mentioned toner images is transferred onto the transferred transfer paper 13 by the transfer paper conveyance device 12. Here, the configuration of the transfer paper conveyance device 12 will be explained.

The conveying device 12 has an endless belt 14 made of dielectric material, which is wound around at least two rollers, in this example a drive roller 15 and a deflection roller 16 .

The three photoreceptor drums 1a, 1b, lc are placed on one side (loose side in this example) of this endless belt extending linearly.
The endless belt 41 is driven by the drive roller 15 at the same speed as the circumferential speed of these drums.

Reference numeral 17 denotes a guide provided at a part of the corner of the endless belt 14. This guide 14 is arranged at a certain minute distance from the surface of the belt, and serves as an aid when the transfer paper being conveyed lifts from the belt. It is made of wood.

In the above transfer operation, each drum 1a, 1b, lc
When the drums are rotated, the transfer paper 13 is sent out from the paper feed cassette 18 toward the endless belt 14 in synchronization with the rotation of these drums.

In this case, the endless belt 14 is charged by a belt static eliminator and pre-charge corona discharger 19, which will be described later. Therefore, the transfer paper 13 sent from the paper feed cassette to the endless belt 14 remains static on the surface of the conveyor belt 14. It is electrically attracted.

As the conveyor belt 1 travels in the direction of the arrow P, the transfer paper 13 is first conveyed to the first photoreceptor 1a while being guided by the guide 17.

At this time, the toner image on the surface of the first photosensitive drum reaches the contact position with the conveyor belt 14 so that it coincides with the surface of the transfer sheet 13, and the first transfer charger 20a is placed opposite to the drum 1a with the belt 14 in between. The toner image on the surface of the drum 1a is transferred to the surface of the transfer paper 13 by the discharge action.

Next, the toner images of the second drum 1b and the third drum 1c are transferred to the transfer paper by the second and third transfer chargers 2.
The images are transferred by the discharge action of 0b and 20c, and a multicolor image is formed on the transfer paper.

During this transfer operation, a DC voltage having the same polarity as the charging polarity of each drum is applied to each transfer charger.

The transfer paper 13, on which the images have been transferred from each drum, is separated from the conveyor belt 14 and sent to the fixing device 24, where the images on the transfer paper are fixed.

On the other hand, the portion of the conveying belt from which the transfer paper has been separated passes through the turning roller 16 and then reaches the belt weight-removing discharger 19, where it is subjected to a neutralizing action and a slight charging action.

That is, an alternating current voltage is applied to the discharger 19 for belt weight removal, and the belt 14 is thereby neutralized, and a direct current voltage (same as the voltage applied to the transfer charger) slightly additionally applied to the discharger 19 is applied. (polarity), the surface of the belt 14 is slightly charged.

As a result of the belt 14 being slightly charged in this way, the next transfer sheet is attracted and held on the surface of the belt 14.

On the other hand, each photosensitive drum that has completed the transfer operation is
After the static electricity is removed by a, 21b, and 21c, a cleaning device (not shown) or a magnetic brush developing device 11a, 1lb
The remaining toner on the surface is cleaned by tllc.

When cleaning the drum surface using the developing devices 11a, 11b, and lie, one copying cycle is completed when the drum rotates two or more times.

In the above-described copying operation, the transfer paper 13 conveyed to each drum by the endless belt 14 is curved along the curvature of the belt 14 when passing through a part of the corner of the belt 14, that is, the region of the drive roller 15.

For this reason, in conventional devices, although the transfer paper is electrostatically attracted to the belt, there is a risk that the leading or trailing edge of the transfer paper may lift off the surface of the belt. As mentioned above, this inconvenience could not be completely avoided even when a guide was provided.

If even a portion of the transfer paper lifts off the endless belt in this way, the image transferred from each drum on the transfer paper will be uneven, and the transfer paper will be charged unevenly by the transfer charger, making it impossible to obtain a uniform transferred image. This becomes difficult.

In the configuration according to the present invention, in order to eliminate the above-mentioned inconvenience,
The drive roller 15 is made of a conductive material, and as shown in FIG. 2, a high voltage is applied to the drive roller 15 by a power source 22.

Furthermore, in this example, the guide 17, which is located opposite the drive roller 15 via the belt 14, is made of a conductive material, and the conductive guide 17 is grounded.

Alternatively, the guide 17 may be made of a conductive material and its surface may be insulated.

With the above configuration according to the present invention, when the endless belt 14 passes through the drive roller 15, the surface of the endless belt 14 is charged by the drive roller 15, and when the transfer paper 13 also passes through the area (corner part) of the drive roller 15, the surface of the endless belt 14 is charged. Recharged.

In this way, the endless belt 14 is charged by the driving roller 15 in addition to being charged by the belt neutralizing and pre-charging corona discharger 19, so that the transfer paper 13 is strongly electrostatically attracted to the surface of the endless belt 14, and the transfer paper 13 is held at a corner. Even when passing through the belt, it does not lift up from the belt surface.

Therefore, the transfer paper 13 is smoothly conveyed to the transfer position, and the images on the surfaces of each drum are evenly transferred to the transfer paper.

Note that it is desirable that the polarity of the voltage applied to the drive roller 15 be opposite to the polarity of the voltage applied to the transfer chargers 20at 20bt 20c.

This is because if the polarity is the same as these polarities, the endless belt 14 that has passed the drive roller 15 will be charged to the opposite polarity to the transfer voltage and reach each transfer charger, resulting in a decrease in transfer efficiency.

It is advantageous if the voltage applied to the drive roller 15 has a polarity opposite to that of the transfer voltage, since this improves the odor transfer efficiency due to the bias effect of the transfer paper voltage.

Also, the material of the drive roller 15 is different from this roller and the endless belt 1.
In order to prevent slippage with 4, it is preferable to use a rubber material with a large coefficient of friction.According to experiments, conductive carbon black is contained in a rubber material such as silicone rubber to reduce the electrical resistance to 1CFΩcm or less. Roller 15 that drives the material
It has been found that the present invention can be effectively applied when used in

Although preferred embodiments of the present invention have been described above, the present invention can be configured in various forms other than the above embodiments.

For example, the present invention can be applied to an electronic copying machine or an electrostatic recording device in which the image carrier is not a photoconductor drum but a photoconductor dot, a dielectric drum, or a belt, and the present invention is also applicable to an electronic copying machine or an electrostatic recording device in which the image carrier is configured as a photoconductor dot or a dielectric drum or belt, and the number of image carriers is not three. , two or one copying machine.

There may be two or more rollers around which the endless belt is wound, and a voltage can be applied to a suitable roller among these rollers.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of an electronic copying machine to which the present invention is applied;
The figure is a partially enlarged perspective view of FIG. 1. lc, lb, lc... image carrier, 1
2... Transfer paper conveyance device, 13... Transfer paper, 14... Endless belt, 15, 16...
··roller.

Claims (1)

[Scope of utility model registration request] At least one image carrier has a dielectric endless belt disposed adjacent to the belt, and at least two rollers around which the endless belt is wound. In a transfer paper conveyance device in an electronic copying machine or the like, which transfers a toner image formed on a carrier onto a transfer paper, at least one of the rollers is made of a conductive material, and the roller is disposed at a position opposite to the roller. The transfer paper conveying device is characterized in that a conductive guide having approximately the same curvature as the conductive material is provided, and a voltage can be applied to the roller made of the conductive material.