JPH06161288A - Device for cleaning transfer belt - Google Patents

Abstract

PURPOSE:To effectively remove stuck toner without exerting influence on a transfer belt, in a simple constitution. CONSTITUTION:Cleaning rollers 31 and 32 abutting on the transfer belt 28 and rotating with it are disposed successively from the upstream side in the rotational moving direction of the transfer belt 28 and simultaneously, cleaning blades 33 and 34 are in press-contact with the outer peripheries of these rollers 31 and 32. Then, the voltage of the same polarity as that possessed by toner is applied to the cleaning roller 31 from a transformer 35 and moreover, the voltage of the polarity reverse to that possessed by the toner is applied to the cleaning roller 32 from the transformer 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer belt cleaning device for transferring a transfer sheet from a pair of registration rollers to a fixing device in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a transfer paper carried out from a pair of registration rollers is conveyed toward a photosensitive drum by a belt made of an elastic body while By applying a predetermined voltage to the transfer roller arranged on the peripheral side, the toner development formed on the surface of the photosensitive drum is transferred to the surface of the transfer paper being conveyed, and the transfer paper after transfer is further conveyed and fixed. There is known an image forming apparatus provided with a so-called transfer belt, which is designed to be carried out to the apparatus. However, in such a device, toner development on the surface of the photosensitive drum or toner of the developing device may scatter, and the scattered toner may adhere to the surface of the transfer belt. It is not preferable because it stains the back surface. Therefore, generally, a cleaning blade made of an elastic body is pressed against the belt surface to collect the adhered toner, or a brush roller in which fine fibers are planted, that is, a fur brush is used to scrape off the adhered toner on the transfer belt surface. A device is provided.

[0003]

However, in the above-mentioned cleaning device using the cleaning blade, since the cleaning blade and the transfer belt are in pressure contact with each other, there is a possibility that the cleaning blade may damage the transfer belt surface. Due to friction between the cleaning blade and the transfer belt, deterioration of the cleaning blade is likely to proceed. Further, since the cleaning blade is pressed against the transfer belt, when the pressing force exceeds an appropriate value, the rotational movement torque of the transfer belt increases, and the transfer paper cannot be conveyed as desired. There was also. On the other hand, in the above-described cleaning device using the fur brush, the fur brush itself is expensive, and a dust collecting device for storing the collected toner without scattering is required, which increases the cost of the cleaning device itself. There is an inconvenience of causing.

The present invention has been made to solve the above problems, and has a simple structure and is capable of effectively removing the adhered toner without affecting the transfer belt. Is intended to provide.

[0005]

SUMMARY OF THE INVENTION The present invention is a device for removing toner adhering to the surface of a transfer belt, wherein the first and the second contacting surfaces of the transfer belt are in contact with the surface of the transfer belt upstream and downstream. A second roller, a same-polarity voltage applying unit that applies a voltage having the same polarity as the toner has to the one roller, and a reverse-polarity voltage that applies a voltage having the opposite polarity to the toner has to the other roller. Applying means,
And a toner removing means for removing the toner attached to the first and second rollers.

[0006]

According to the present invention, both the first roller and the second roller are in contact with the surface of the transfer belt and are rotated by the rotational movement of the transfer belt. At this time, a voltage having the same polarity as that of the toner, which is the developer, is applied to the one roller from the same polarity voltage applying means, while the polarity of the toner from the opposite polarity voltage applying means is applied to the other roller. And a voltage of opposite polarity is applied. Then, the toner adhered to the surface of the transfer belt is rotated by the transfer belt,
It passes through the location of both rollers. At this time, there are two types of toner, one having its own polarity and the other having the opposite polarity at the time of development or transfer, and these toners sequentially pass through both rollers. As a result, the toner having the opposite polarity is attracted to the roller surface to which the same polarity voltage is applied, and the toner having its own polarity is attracted to the roller surface to which the opposite polarity voltage is applied. As a result, all the toner attached to the surface of the transfer belt is removed and collected. And
Further, the toner adsorbed on the surfaces of the first and second rollers is collected from each roller by the toner removing means.

[0007]

First, a copying machine (image forming apparatus) to which a cleaning device for a transfer belt according to the present invention is applied will be described with reference to FIG.
Will be explained.

The copying machine F has a contact glass 1 and a document presser 2 on its upper surface, and is provided with various components such as an optical system L, an image forming means P and a transfer paper conveying system. .

The optical system L includes an exposure lamp 3 and a reflection plate 4.
A light source unit that reciprocates to scan the document, and reflecting mirrors 6 and 7 that reflect light reflected from the document to form an optical path.
8, a lens 10 for adjusting the magnification of a formed image, and a fixed mirror 9 for reflecting the reflected light toward a photosensitive drum 11 described later.

The image forming means P includes a photosensitive drum 11 on the surface of which an electrostatic latent image is formed, a charging device 12 for charging the photosensitive drum 11 to a predetermined potential, and an unnecessary portion of the charge on the photosensitive drum 11. A blank lamp 13 for removal, a developing device 14 for adhering toner to the electrostatic latent image on the photoconductor drum 11 to develop it, which will be described in detail later. The toner image is transferred to transfer paper and transferred from the photoconductor drum 11. Separate the paper,
The transfer device 15 and the photosensitive drum 1 which are further transported to the downstream side
1 is composed of a photoconductor cleaning device 16 and the like for cleaning the toner remaining on the surface.

On the other hand, as a transfer paper transport system, paper feed cassettes 17 and 18 for storing transfer papers of different sizes, paper feed rollers 19 and 20 for feeding the transfer papers, and a transporter in order from the upstream side in the transport direction. Roller pair 21 and registration roller pair 2
2 are provided. Further, a fixing device 23 for fixing the toner image transferred on the transfer sheet to the transfer sheet, a discharge roller 24 for discharging the transfer sheet to a discharge tray 25, and the like are arranged on the downstream side in the transporting direction of the transfer sheet after the transfer. ing.

In the copying machine F having the above-mentioned structure, the light of the halogen lamp 3 is reflected by the original document, and the reflected image is passed through the reflecting mirrors 6, 7, 8 and the lens 10 and the fixed mirror 9 to the photosensitive drum 11. Be led to. The photosensitive drum 11 is shown in FIG.
While being rotated in the direction of the arrow, after being charged to a predetermined voltage by the charging device 12, the original image is exposed by being irradiated to form an electrostatic latent image. The electrostatic latent image on the photoconductor drum 11 is developed by the developing device 14 and then transferred by the transfer device 15 onto the transfer paper fed from the paper feed cassette 17 or 18. The transfer paper after the transfer is the transfer device 1
The sheet is separated from the photosensitive drum 11 by 5 and is conveyed, and is ejected onto the ejection tray 25 via the fixing device 23 and the ejection roller 24.

In the copying machine F, the developing device 1
It is assumed that a developer having a negative polarity has been applied to the developer, that is, the toner used in No. 4.

Next, a specific structure of the transfer device 15 will be described with reference to FIG. In the figure, the transfer device 1
Reference numeral 5 denotes a transfer belt 28 that conveys the transfer paper fed by the registration roller pair 22 to the fixing device 23.
A transfer roller 29 for transferring the toner development formed on the surface of the photosensitive drum 11 to the surface of the transfer paper on the transfer belt 28; and a transfer belt of the present invention for removing the toner adhering to the surface of the transfer belt 28. Cleaning device 3
7 (hereinafter, abbreviated as a cleaning device).

The transfer belt 28 is an endless belt made of urethane rubber or the like. The transfer belt 28 is provided immediately upstream of the fixing device 23 and immediately downstream of the registration roller pair 22. The driven roller 27 and the intermediate rollers 30a and 30b are stretched, and the driving roller 2
6 is rotated by a motor (not shown),
It is adapted to be rotationally moved in the direction of the arrow in FIG.

The transfer roller 29 is the transfer belt 2
It is arranged at a position facing the photoconductor drum 11 across 8 and its outer peripheral surface abuts on the inner peripheral surface of the transfer belt 28. The transfer roller 29 is adapted to transfer the toner development formed on the surface of the photoconductor drum 11 to the transfer paper on the transfer belt 28 when a high voltage is supplied from a transformer (not shown) at a predetermined timing. ing.

On the other hand, the cleaning device 37 is disposed below the transfer belt 28 at a substantially central position between the driving roller 26 and the driven roller 27. As shown in FIG. 1, the cleaning device 37 includes the cleaning roller 3 disposed on the upstream side in the rotational movement direction of the transfer belt 28.
1 (first roller) and a cleaning roller 32 (second roller) arranged downstream thereof. Both the rollers 31 and 32 are the transfer belt 28.
A metal roller having a single structure, which is brought into contact with the surface of the transfer belt 28 in the width direction of
It is designed to be rotated in the direction of the arrow in FIG. The cleaning rollers 31 and 32 have a transformer 35 (same-polarity voltage applying means) and a transformer 36, respectively.
A voltage of a predetermined pressure is applied from the (reverse polarity voltage applying means), and the cleaning roller 31 is negatively charged by applying a negative voltage by the transformer 35, while the cleaning roller 32 is charged. Is positively charged when a positive voltage is applied by the transformer 36. In the embodiment, a voltage of -600V is applied to the cleaning roller 31 and a voltage of + 1000V is applied to the cleaning roller 32. Further, cleaning blades 33 and 34 (toner removing means) are pressed against the outer peripheral surfaces of the rollers 31 and 32, respectively.
The toner adsorbed on the surface of each roller 31, 32 is scraped off by these cleaning blades 33, 34.

Next, the operation of the cleaning device having the above structure will be described.

When copying is started in the copying machine F having the above-mentioned structure, the developing device 14 causes the photosensitive drum 11 to move.
Toner is supplied to the surface, and toner development is formed on the surface of the photosensitive drum 11. On the other hand, in the transfer device 15,
While the transfer belt 28 is rotationally moved, the transfer paper fed from the registration roller pair 22 is conveyed toward the photosensitive drum 11 at a predetermined timing. Then, when the transfer paper reaches the photosensitive drum 11, a high voltage is applied to the transfer roller 29, and the transfer paper is charged to a predetermined voltage via the transfer belt 28. As a result, the toner development formed on the surface of the photoconductor drum 11 is transferred to the surface of the transfer paper due to the potential difference between the transfer paper and the photoconductor drum 11.
The transfer sheet after the transfer is further transported to the downstream side by the transfer belt 28, and is separated from the position of the drive roller 26 to the fixing device 23 and carried out.

However, during the above process of the copying machine F, the residual toner on the photoconductor drum 11 is collected at the time of toner development formation on the photoconductor drum 11, at the time of transferring the toner development to the transfer paper, or after the transfer. At times, the toner may be scattered, and such scattered toner adheres to the surface of the charging belt 28. The toner thus attached to the transfer belt 28 is carried to the cleaning device 37 by the rotational movement of the transfer belt 28, and is brought into contact with the outer peripheral surfaces of the cleaning roller 31 and the cleaning roller 32 of the cleaning device 37 sequentially.

By the way, most of the toner adhered to the surface of the transfer belt 28 retains the polarity (negative polarity) of the toner itself, but a part thereof has a reverse polarity at the time of the above-mentioned development or transfer. Those having (positive polarity) are also included. Therefore, when such toners having two kinds of polarities are sequentially contacted with the outer peripheral surfaces of the cleaning roller 31 and the cleaning roller 32, first, the opposite polarity (positive polarity) toner is negatively charged. The transfer belt 28 is attracted to the surface of the cleaning roller 31 and
Removed from. At this time, the toner having the conventional polarity (negative polarity) is charged by the cleaning roller 31, and the charge of the toner is further increased. Then, when the negative polarity toner reaches the positively charged cleaning roller 32 and comes into contact with the surface thereof, it is adsorbed on the surface of the cleaning roller 32 and removed from the transfer belt 28. That is, as a result, all the toner attached to the surface of the transfer belt 28 is removed by the cleaning roller 31 and the cleaning roller 32. And each roller 31,
The toner adsorbed on the surface of the roller 32 is scraped off from the surface of the roller 31, 32 by the cleaning blades 33, 34 pressed against the outer peripheral surfaces of the roller 31, 32 as the rollers 31, 32 rotate. It is designed to be stored in the collection case.

As described above, in the cleaning device having the above structure, the cleaning belt is brought into contact with the surface of the transfer belt 28,
Since the cleaning roller 31 and the cleaning roller 32 that are rotated together collect and collect the toner adhering to the surface of the transfer belt 28, the cleaning blade is not pressed against the transfer belt as in the conventional example, and therefore the cleaning is performed. There is no possibility that the transfer belt is damaged due to the pressure contact between the blade and the transfer belt. Further, since the cleaning roller 31 and the cleaning roller 32 are rotated along with the rotational movement of the transfer belt 28, the rotational movement torque of the transfer belt 28 is not increased, and the transfer paper can be properly conveyed. Further, a pair of cleaning rollers 3
Since it is a relatively simple structure that only 1 and 32 are charged,
There will be no increase in cost.

Further, in the embodiment, the opposite polarity (positive polarity) toner having a relatively small adhesion ratio is first removed by the cleaning roller 31 charged to the negative polarity, and
At this time, the remaining toner having a large adhesion ratio, that is, the negative polarity toner is charged by the cleaning roller 31 to increase the charge of the toner, so that the cleaning roller 32 on the downstream side is charged to the positive polarity. The potential difference between the negative polarity toner and the negative polarity toner is enlarged, the removal ability of the cleaning roller 32 with respect to the negative polarity toner is improved, and the toner attached to the transfer belt 28 can be more reliably removed and collected.

In the above embodiment, an example of a copying machine using a toner having a negative polarity as a developer has been described, but a toner having a positive polarity can be used. In this case, the cleaning roller 31 may be positively charged and the cleaning roller 32 may be negatively charged. Further, in the embodiment, the cleaning roller 31 has -600V, and the cleaning roller 32 has
Although a voltage of +1000 V is applied to each of the above, this value is an example, and may be appropriately set so that the toner attached to the transfer belt 28 can be more surely adsorbed and collected. Further, in the embodiment, the cleaning blades 33 and 34 are connected to the cleaning rollers 3 respectively.
The adsorbed toner is removed by being pressed against the outer peripheral surfaces of the cleaning rollers 1 and 32, but the toner removing means of the cleaning rollers 31 and 32 is not limited to this, and the toner can be effectively removed. It may be configured as appropriate.

[0025]

As described above, according to the present invention, in the apparatus for removing the toner adhering to the surface of the transfer belt, the transfer belt is contacted on the upstream side and the downstream side in the rotational movement direction of the transfer belt. The first and second rollers, the same polarity voltage applying unit that applies a voltage having the same polarity as the toner has to one roller, and the opposite polarity that applies a voltage having the opposite polarity to the toner has to the other roller. Since the polarity voltage applying means and the toner removing means for removing the toner adhering to the first and second rollers are provided, the transfer belt is damaged by the pressure contact of the cleaning blade, and the rotational movement torque of the transfer belt is increased. Without inconvenience
It is possible to effectively remove the toner attached to the transfer belt.

[Brief description of drawings]

FIG. 1 is an enlarged schematic view showing the vicinity of a transfer device of an image forming apparatus to which a transfer belt cleaning device of the present invention is applied.

FIG. 2 is a schematic configuration view showing an image forming apparatus to which a cleaning device for a transfer belt of the present invention is applied.

[Explanation of symbols]

 28 transfer belt 31, 32 cleaning roller 33, 34 cleaning blade 35, 35 transformer 37 cleaning device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuki Ito 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd.

Claims (1)

[Claims] 1. An apparatus for removing toner adhering to the surface of a transfer belt, wherein first and second rollers contacting the surface of the transfer belt are provided on the upstream side and the downstream side in the rotational movement direction of the transfer belt. The same polarity voltage applying means for applying a voltage of the same polarity as the toner has to the roller, and the reverse polarity voltage applying means for applying a voltage of the opposite polarity to the toner has to the other roller; A transfer belt cleaning device, comprising: a toner removing unit that removes toner adhering to the second roller.