JP3246687B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visualizing an electrostatic latent image formed on an image carrier as a toner image, transferring the toner image onto a transfer material by a transfer device, and transferring the image after transfer. The present invention relates to an image forming apparatus that cleans toner remaining on a body with a cleaning device.

[0002]

2. Description of the Related Art In an image forming apparatus of the above-mentioned type constituted as an electronic copying machine, a printer, a facsimile or the like, a filming substance adheres in a film form on an image carrier with the use thereof. Since this filming substance causes deterioration of the image quality of the toner image, it should be removed at an early stage.

Therefore, conventionally, a filming substance attached to the image carrier has been removed by a filming removing brush to prevent the image quality of the toner image from deteriorating (see, for example, JP-A-2-191980). As such a filming removal brush, a conductive metal fiber made of a synthetic fiber or a thin metal wire is used, but when the latter metal fiber is used, the flexibility of the thin metal wire causes
The metal fibers follow the surface of the image carrier and come into contact therewith, and since the hardness of the metal fibers is relatively high, the efficiency of scraping off the filming substance on the image carrier is increased.

However, in a filming removal brush using metal fibers, the fibers may cause metal fatigue due to external force repeatedly applied to the fibers, and the fibers may be broken and fall off. Most of the metal fibers thus dropped fall downward and do not affect the image forming operation, but a part of the metal fiber is transported while being attached to the image carrier, and this has an adverse effect on the image forming operation. May have an effect.

For example, when a corona discharger is used as a transfer device for transferring a toner image on an image carrier to a transfer material, conductive metal fibers adhering to the image carrier fall into a casing of the corona discharger. The corona from the charge wire of the corona discharger flows through the metal fiber made of a thin conductor, resulting in a short-circuit phenomenon called a leak.
Poor transfer of the toner image to the transfer material may occur.

In order to eliminate the above-mentioned inconvenience, the metal fibers adhering to the image carrier may be collected and removed by a collecting member. However, providing such a collecting member increases the manufacturing cost of the image forming apparatus. In addition, the management cost for maintaining it is also required.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which a dropped metal fiber does not adversely affect an image forming operation without providing a special collecting member.

[0008]

In order to achieve the above object, the present invention provides an image carrier on which an electrostatic latent image is formed, a magnetic brush of a developer, and the electrostatic latent image formed by toner. A developing device that visualizes the toner image as a toner image, a transfer device that transfers the toner image onto a transfer material, a cleaning device that cleans toner remaining on the image carrier after the transfer,
An image forming apparatus comprising: a filming removing brush for scraping off a filming substance attached to the image carrier; and wherein the filming removing brush is formed of conductive metal fibers. L in body axis direction
₁ , when the axial width of the filming removal brush in the image carrier axis direction is L ₂ , and the maximum image width of the toner image formed on the image carrier in the image carrier axis direction is L ₃ , L ₁ ≧ L _2> is proposed an image forming apparatus in which set each width to satisfy L _3.

In order to achieve the same object, an image carrier on which an electrostatic latent image is formed and a magnetic brush of developer are formed.
A developing device for visualizing the electrostatic latent image as a toner image with the toner, a transfer device for transferring the toner image onto a transfer material, and a cleaning device for cleaning toner remaining on the image carrier after the transfer And a filming removal brush for scraping off filming material adhering to the image carrier. The filming removal brush is formed of conductive metal fibers and swings in the axial direction of the image carrier. In the image forming apparatus movably supported, the axial width of the magnetic brush in the image carrier axis is L ₁ , and the total width obtained by adding the swing stroke to the axial width of the filming removing brush in the image carrier axis is L _4. when the maximum image width of the image carrier width direction of the toner image formed on the image bearing member has a L _3, L ₁ ≧ L ₄
> Proposes an image forming apparatus set each width to satisfy L _3.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic view showing an image forming apparatus according to an embodiment of the present invention. First, the overall structure and operation will be briefly described.

In FIG. 1, a belt-shaped photoreceptor 1, which is an example of an image carrier, is wound around a drive roller 2a and another appropriate number of support rollers 2, and is rotated in the direction of arrow A by the rotation of the drive roller 2a. Is driven. At this time, the photoreceptor 1 is uniformly charged to a predetermined polarity by the charger 3 constituted by a corona discharger.

The charged photoreceptor 1 is image-exposed by an image forming optical system 4 to form a predetermined electrostatic latent image on the photoreceptor 1. This latent image is visualized as a toner image when passing through the developing device 6.

On the other hand, a transfer paper, which is an example of a transfer material, is fed from the paper supply unit 9 toward the photoreceptor 1, and the toner image on the photoreceptor 1 is formed by the discharge action of the transfer device 7 including a corona discharger. It is transferred onto transfer paper. Next, the transfer paper is separated from the photoreceptor 1 while being subjected to the discharging action of the separation device 7a also constituted by a corona discharger. The transfer paper after separation is transported to the fixing device 11 by the transport belt 10, and then continuously out of the machine. Is discharged.

When the toner image on the transfer paper passes through the fixing device 11, it is fixed on the transfer paper. The toner remaining on the photoconductor 1 after the transfer of the toner image is cleaned and removed by the cleaning device 8. Thus, the photoconductor 1 is used repeatedly.

The developing device 6 shown in FIG. 1 has an appropriate number of developing sleeves 20, as shown in FIG. 2, in which a magnet 21 is immovably disposed.
Is rotationally driven, so that the developer is carried on the sleeve 20 and transported. As the developer, at least a part thereof is made of a magnetic material. For example, a two-component developer having a toner and a carrier or a one-component developer not containing a carrier is used. Regardless of which developer is used, when the developer is carried on the developing sleeve 20 and transported, the magnetic brush D is formed by the action of the magnetic force of the magnet 21, and the toner is formed on the photoconductor 1 by the toner. The electrostatic latent image is visualized as a toner image.

During the image forming operation as described above, as described above, the filming substance on the photoreceptor 1 adheres in the form of a film, and if left unattended, the image quality of the toner image deteriorates. I do. Such deposits are different from the toner and paper powder remaining on the photoconductor 1 after the transfer of the toner image, and are considered to be formed on the photoconductor 1 due to the following reasons.

(1) Fine powder of the toner in the developer used in the developing device 6 or fine powder of the carrier when a two-component developer is used adheres to the photoreceptor 1. (2) The talc and other chemical components in the transfer paper contain the photoreceptor 1
Stick on top. (3) The nitrogen oxide NOx formed by the ozone O ₃ released from the corona discharger adheres to the photoreceptor 1.

Such a filming substance is used for the photosensitive member 1
It is difficult to remove the toner by the cleaning device 8 for cleaning. Particularly in a high-speed image forming apparatus having a high copy speed, the moving speed of the photoconductor is also high, so that the collision energy between the developer and the transfer paper becomes large, and the generation of fine powder is caused. The amount is large, and the speed at which it adheres to the photoreceptor also increases. In addition, since the amount of ozone released from the corona discharger also increases, a filming substance is easily formed on the photoreceptor.

For this reason, in a particularly high-speed image forming apparatus, a filming removing device 5 is provided separately from the cleaning device as shown in FIG. This film removing device has a brush roller 22 as shown in FIGS. 1 and 2. The brush roller 22 is composed of a film removing brush 12 made of conductive metal fibers woven into a base cloth, and the base thereof. It is composed of a roller-shaped core material 23 wound with a cloth. The brush roller 22 is used for the photosensitive member 1.
, And is configured to be rotatably driven in the counterclockwise direction in FIG. The backup roller 13 is provided at a position facing the brush roller 22.

As described above, at a time other than when a toner image is formed on the photoreceptor 1 and an image forming operation is executed, for example, after the main switch of the image forming apparatus is turned on and until a copy is possible. In the meantime, the filming removing brush 12 of the brush roller 22 rotating in the counterclockwise direction comes into contact with the photoconductor 1, and the filming substance attached to the photoconductor 1 is scraped off by the brush 12. After finishing the filming substance removing operation, the brush roller 22 is separated from the photoconductor 1. Therefore, the toner image formed on the photoconductor 1 is not disturbed by the brush roller 22.

Since the filming substance on the photosensitive member 1 is removed as described above, the image quality of the toner image formed on the photosensitive member can always be kept high.

Further, since metal fibers are used as the filming removing brush 12, filming substances adhered to the photoreceptor 1 with a strong force can be effectively scraped off.
In order to further enhance the effect, it is preferable to form the brush 12 in a loop shape and increase the contact area of the brush 12 with the photoconductor 1. When the brush 12 is formed in a loop shape, an effect that the photoconductor 1 is hardly damaged can be obtained.

With the rotation of the brush roller 22, the filming removing brush 12 causes the flicker 2 as shown in FIG.
At this time, the filming substance adhering to the brush 12 is knocked down, and the substance is collected in the tray 25.

As the metal fiber of the filming removing brush 12, for example, a small-diameter wire made of stainless steel SUS316 and having a diameter of 12 μm or a product name “Bolfa” manufactured by Unitika Ltd. can be advantageously used.

The use of the filming removal brush 12 made of metal fibers provides the above-described excellent advantages, but on the other hand, the filming removal brush 12 made of such metal fibers does not affect the flicker 24. During the contact and separation, the deformation is repeated, and the metal falls out of the brush roller 22 due to the metal fatigue.
If it falls on the casing of the corona discharger constituting the separation device 7a, the transfer failure of the toner image is caused or the separation performance of the transfer paper is deteriorated as described above.

If the above-mentioned trade name "Bolfa" is used as the filming removing brush 12, it is an amorphous metal and does not have a crystal structure, so that there is no crystal defect causing metal fatigue. It is extremely hard to be tired, and it can be prevented from falling off, but it cannot be completely eliminated.

As described above, the use of the recovery member for recovering the dropped metal fibers involves disadvantages such as an increase in cost.

The present invention proposes an image forming apparatus capable of preventing a dropped metal fiber from adversely affecting an image forming operation without using a collecting member or the like.
It was completed through the following process.

The present inventor repeatedly examined the path along which the metal fibers of the filming removal brush which had fallen off the brush roller 22 and adhered to the photoreceptor 1 were conveyed. As a result, when the developing device 6 that forms the magnetic brush D of the developer is used, the metal fiber attached to the photoconductor 1 is scraped off by the magnetic brush D and collected by the developing device 6. Could be found. However, in the conventional image forming apparatus, since such a fact is not considered at all, the metal fibers adhered to the photoreceptor fall to a casing of the transfer device, and the above-described problem occurs.

The new facts described above will be clarified more specifically. FIG. 4 is an explanatory view corresponding to FIG. 2 for explaining the above-mentioned drawbacks in the conventional image forming apparatus, and each element thereof is denoted by the same reference numeral as that shown in FIG. 1 and FIG.

In FIG. 4, a magnetic brush D is carried on a developing sleeve 20 of the developing device 6. The width of the brush D in the photoconductor axial direction is l ₁ , and the filming removing brush 1 is provided.
The second photoreceptor axial width l _2, the maximum image width of the photoreceptor axial direction of the toner image formed on the photosensitive member 1 and l _3. The photoconductor axial width means a width in a direction orthogonal to the moving direction A of the photoconductor 1.

Here, in the conventional image forming apparatus, the widths are usually set to l ₂ > l ₁ > l ₃ .
This is for the following reason. (1) Since the filming removing brush 12 cleans the photoreceptor 1 in a broad sense, like the cleaning member of the cleaning device, the width l of the photoreceptor in the axial direction is increased.
₂ should be set larger than the width l ₁ of the magnetic brush D in the photoconductor axial direction so that no filming material remains on the photoconductor. (2) The main cause of the filming substance on the photoconductor 1 is that the magnetic brush D comes into contact with the photoconductor 1 and the fine powder of the toner adheres to the photoconductor 1. the timing material completely removed, the width l ₂ of the filming removing brush 12, is required to be greater than the width l ₁ of the magnetic brush D. (3) On the other hand, to form a high quality toner image on the photosensitive member 1, than the maximum image width l ₃ of the photosensitive body axis direction, it should increase the width l ₁ of the magnetic brush D.

For the reasons described above, conventionally, each width is set to l ₂ >
That is, l ₁ > l ₃ was set.

The inventor has operated such a conventional image forming apparatus and examined the casing of the transfer or separation apparatus (FIG. 1). As a result, the casing corresponding to the outside of the magnetic brush D shown in FIG. There were metal fibers that had fallen into the area. The length was most often 1 to 2 mm, hardly 3 mm or more, and the maximum length was about 5 mm.

From the above description, it can be understood that the metal fibers attached to the portion of the photoconductor 1 in contact with the magnetic brush D are removed from the photoconductor 1 by the magnetic brush D,
This means that the toner is collected in the developing device 6 and is not transported downstream of the developing device 6. The metal fibers collected by the developing device 6 accumulate in the lower portion of the casing of the developing device 6 due to gravity acting thereon, and the fibers do not adversely affect the developing operation.

As described above, if the magnetic brush D is used,
Even without using a recovery member, the metal fibers that adhere to the photoreceptor 1 are removed and recovered, and the occurrence of troubles due to the fibers can be prevented.

However, in the conventional image forming apparatus, the width l _{2 of the} filming removal brush 12 is
Is set to be larger than the width l ₁ of the magnetic brush D.
As a result, all of them could not be removed, and the metal fibers fell down on both ends of the casing of the transfer device and the separation device, which caused the problem of causing a leak.

According to the present invention, as shown in FIG. 2, the width of the magnetic brush D in the axial direction of the photoconductor is L ₁ , the width of the filming removing brush 12 in the axial direction of the photoconductor is L ₂ , when the maximum image width of the photoreceptor axial direction of the toner image formed on the 1 was L _3, the respective width to satisfy L ₁ ≧ L _2> L ₃ is set.

According to the above-described configuration, since the width L ₁ of the magnetic brush D is set to be equal to or larger than the width L ₂ of the filming removal brush 12, the metal L that has fallen off from the brush 12 and adhered to the photoreceptor 1 has The fibers are all removed and collected by the magnetic brush D, and the fibers are not conveyed to the transfer device 7 or the separation device 7a located downstream of the magnetic brush D in the photoconductor moving direction A. Therefore, these devices 7, 7
It is possible to prevent the occurrence of a leak due to the metal fiber at a.

However, according to this configuration, the filming substance remains attached to the photoconductor portions on both outer sides of the filming removing brush 12, and the filming substance cannot be removed. However, the maximum image width L ₃ of the toner image formed on the photoconductor 1 is smaller than the width L ₁ of the magnetic brush D and the width L ₂ of the filming removal brush 12.
Even if the filming substance adheres to the photoconductor portion outside of the photoconductor 2, the image quality of the toner image does not deteriorate.

In this way, the filming substance can be removed from the photoreceptor 1 without using a special recovery member, and the quality of the toner image can be always kept high.

When removing the filming substance on the photosensitive member 1 by the filming removing brush 12, the filming removing brush 12 is moved in the axial direction of the photosensitive member, that is, as shown in FIG. Photoconductor 1
3 is swingably supported in a direction X perpendicular to the movement direction A of the brush, and the brush 12 is used to remove the filming substance.
The present applicant has proposed an image forming apparatus that swings between a position indicated by a solid line and a position indicated by a chain line.

[0044] In the case of such an image forming apparatus, the photoreceptor direction width of filming removing brush 12, the total width plus the swing stroke S and L _4, the photoconductor axial width of the magnetic brush D If L ₁ and the maximum image width L ₃ of the toner image formed on the photoreceptor 1 are set to L ₁ ≧ L ₄ > L ₃ , the same operation and effect as those shown in FIG. 2 can be obtained. Can be. The other configuration of the image forming apparatus shown in FIG. 3 is the same as that described above with reference to FIGS. 1 and 2.

[0045]

According to the first and second aspects of the present invention,
Even without providing a special member for recovering the metal fibers dropped from the filming removal brush, it is possible to prevent a problem that the fibers adversely affect the image forming operation. For this reason, there is an advantage that the structure of the image forming apparatus can be simplified and its cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a relationship among a developing device, a filming removal brush, and a toner image of the image forming apparatus illustrated in FIG. 1;

FIG. 3 is an explanatory view similar to FIG. 2 of another embodiment.

FIG. 4 is an explanatory view similar to FIG. 2 of a conventional image forming apparatus.

[Explanation of symbols]

6 developing device 7 transfer device 8 cleaning device 12 filming removing brush D magnetic brush L ₁ width L ₂ width L ₃ width L ₄ width S swinging stroke

Claims (2)

(57) [Claims] 1. An image carrier on which an electrostatic latent image is formed, a developing device for forming a magnetic brush of a developer, and visualizing the electrostatic latent image as a toner image by using the toner; It has a transfer device that transfers an image onto a transfer material, a cleaning device that cleans toner remaining on the image carrier after the transfer, and a filming removal brush that scrapes off a filming substance attached to the image carrier. An image forming apparatus in which the filming removing brush is formed of conductive metal fibers, wherein the width of the magnetic brush in the image carrier axial direction is L ₁ , and the width of the filming removing brush in the image carrier axial direction is L ₁ . L ₂ , when the maximum image width of the toner image formed on the image carrier in the image carrier axis direction is L ₃ , each width is set so as to satisfy L ₁ ≧ L ₂ > L _3. Characteristic image forming apparatus. 2. An image carrier on which an electrostatic latent image is formed, a developing device which forms a magnetic brush of a developer, and visualizes the electrostatic latent image as a toner image by using the toner; It has a transfer device that transfers an image onto a transfer material, a cleaning device that cleans toner remaining on the image carrier after the transfer, and a filming removal brush that scrapes off a filming substance attached to the image carrier. An image forming apparatus in which the filming removing brush is formed of conductive metal fibers and is supported so as to be swingable in the axial direction of the image carrier, wherein the width of the magnetic brush in the axial direction of the image carrier is reduced. L ₁ is the total width obtained by adding the swing stroke to the image carrier axial width of the filming removal brush, and L ₄ is the maximum image width of the toner image formed on the image carrier in the image carrier width direction. when was the L _3, L An image forming apparatus wherein each width is set so as to satisfy ₁ ≧ L ₄ > L ₃ .