JP3129425B2 - Filming removal device for latent image carrier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing filming of a latent image carrier in an image forming apparatus.

[Conventional technology]

Conventionally, an image forming apparatus that forms an electrostatic latent image on a latent image carrier, visualizes the latent image with toner, transfers the toner image to a transfer material, and repeatedly uses the latent image carrier has been conventionally used. As is well known, such an apparatus is configured as, for example, an electronic copier, a printer, a facsimile, or the like.

In this type of image forming apparatus, there is a possibility that a so-called filming phenomenon occurs in which toner, paper powder, additives contained in paper, etc. are fixed to the surface of the latent image carrier in a thin film.
When such a phenomenon occurs, a partial increase in the density of the toner image and background contamination occur, and the image quality of the toner image is significantly reduced.

Therefore, various devices for removing filming on the latent image carrier have been conventionally proposed.Filming is removed while polishing the surface of the latent image carrier with an abrasive or a polishing brush.
A typical example is an apparatus in which a blade is pressed against a latent image carrier to scrape filming (see, for example,
JP-A-62-119567, JP-A-60-107076, JP-A-60-107
-119589).

However, according to the conventional apparatus as described above, since a special member for removing filming such as a polishing brush is required, there is a problem that the cost increases, and the brush and the blade wear the latent image carrier, There is a possibility that a streak-like abnormal image is generated or the life of the latent image carrier is shortened.

Therefore, the applicant of the present invention has provided a developing device for visualizing an electrostatic latent image and a cleaning device for cleaning the surface of a latent image carrier after transfer of a toner image. A configuration has been proposed in which a device having a developer carrier having a toner and a carrier and carrying an agent carrying a cleaning agent is used as these devices, and filming of the latent image carrier is removed by using these agents (Japanese Patent Application No. Hei 10-26139). 1-284058 and 1-312628). According to the filming removing device, it is possible to suppress an increase in cost and a reduction in the life of the latent image carrier.

[Problems to be solved by the invention]

However, in the conventional filming removing apparatus of the above type, no special consideration is given to the particle size of the carrier particles in the agent for removing filming, and the filming removing effect depends on the carrier used. There was a risk of lowering.

The present invention departs from the novel recognition described above,
An object of the present invention is to provide a filming removal device for a latent image carrier that can further enhance the filming removal effect.

[Means for solving the problem]

In order to achieve the above object, the present invention has an agent carrier disposed opposite a latent image carrier on which a toner image is formed during image formation, and carries an agent having a carrier on the agent carrier by magnetic force. The latent image carrier is transported to a region between the latent image carrier and the agent carrier, and the transported agent is rubbed against the surface of the latent image carrier. At a time other than the time of image formation when an image is formed, a larger amount of agent is transported to an area between the latent image carrier and the agent carrier than at the time of image formation, and the filming removal operation of the latent image carrier is performed. At the same time, amorphous carrier particles are used as the carrier particles of the agent, and the particle size of the carrier particles is 50 μm.
A filming removal device characterized by having a value of m or less is proposed.

〔Example〕

Hereinafter, an embodiment in which the filming removing device according to the present invention is configured by a magnetic brush cleaning device will be described. FIG. 1 shows a color copier equipped with such a cleaning device. First, the whole configuration will be clarified for understanding the present invention.

In this copying machine, first, illumination scanning is performed on a document (not shown) on the contact glass 10 by moving the illumination device 11 to the right in the figure together with the first mirror 12. The scanning light image at this time enters the lens 15 via the second mirror 13 and the third mirror 14 moving in the same direction, and then passes through the fourth mirror 16 and the filter device 17,
An image is projected on a drum-shaped photosensitive member 18 which is an example of a configuration of a latent image carrier. The photoreceptor 18 rotates clockwise in FIG. The filter device 17 has a plurality of color separation filters, one of which, for example, a light image of a blue component is first extracted, and this light image is already uniformly charged by the charger 19. An image is projected on the photoreceptor 18, thereby forming an electrostatic latent image on the photoreceptor.

A yellow developing device 21Y, a magenta developing device 21M, and a cyan developing device 21C are provided below the photoreceptor 18, respectively. The electrostatic latent image is first formed into a toner image by yellow toner of the yellow developing device 21Y.

A transfer paper, which is an example of a transfer material sent from a paper supply unit 23, is wound around the transfer drum 22, and the toner image is transferred onto the wound transfer paper by the transfer charger 20.

Similarly, a magenta magenta toner image and a cyan cyan toner image formed on the photoreceptor are respectively transferred onto a transfer sheet and superimposed. When a black toner image is obtained, the electrostatic latent image is visualized by the black toner of the black developing device 21B. In the case of black exposure, an ND filter is used as a filter.

After the transfer of the toner image, the transfer paper is separated from the transfer drum 22 by the separation charger 24 and the separation claw 25, and the separated transfer paper is discharged outside the machine as a copy paper through the fixing device 26. On the other hand, the residual toner on the photoreceptor 18 after the transfer of each toner image onto the transfer paper is removed each time by the magnetic brush cleaning device 27 to prepare for the next image formation.

FIG. 2 shows details of the magnetic brush clearing device 27.

The photoreceptor 18 rotates in the direction of the arrow.
A pre-cleaning charger 28 is provided on the downstream side of the transfer section, which is a contact section between the photoconductor 18 and the transfer drum 22, so as to face the photoconductor 18.

The cleaning device 27 includes a pre-cleaning charger.
Downstream of 28, provided with a plurality of magnets 31 therein, for example, in which a cleaning sleeve 32 made of a conductive non-magnetic material such as aluminum (individual magnets the sign of P ₁ to P ₆ Attached). The cleaning sleeve 32 is arranged to face the photoconductor 18 on which a toner image is formed as described above during image formation. The sleeve 32 is an example of a configuration of an agent carrier. In this embodiment, the cleaning sleeve 32 is rotated clockwise by an unillustrated drive motor with respect to the fixed magnet 31 by a drive motor (not shown). It is designed to be driven. The magnetic poles of each magnet 31 in the circumferential direction of the cleaning sleeve 32 are as shown with S and N in FIG.

After the transfer of the toner image, when the toner remaining on the photoreceptor 18 comes to the pre-cleaning charger 28,
Due to the corona discharge by the pre-cleaning charger 28, a charge of a certain polarity (positive in the example in the drawing) is given to the toner particles so as to facilitate cleaning.

On the other hand, on the peripheral surface of the cleaning sleeve 32, a powdery cleaning agent C having a magnetic carrier and magnetic or non-magnetic toner is carried by the magnetic force of the magnet 31, and a magnetic brush is formed by the carrier. The toner and the carrier are frictionally charged with different polarities, and the toner particles are electrostatically attached to the carrier particles. As described above, the cleaning agent C, which is at least partially made of a magnetic material, is rotated by the clockwise rotation of the cleaning sleeve 32.
And is transported to the cleaning area X between the cleaning sleeve 32 and the photoreceptor 18, where the photoreceptor
Rub on the surface of 18.

When the residual toner charged by the pre-cleaning charger 28 arrives at the cleaning area X facing the cleaning sleeve 32, the residual toner is converted into a bias voltage having a polarity opposite to the charge polarity of the toner (in the example of FIG. ) Is applied to a cleaning carrier having a negative charge on the cleaning sleeve 32 to which the cleaning sleeve 32 is applied with an electrostatic attraction force and a mechanical scavenging force. In this way, the residual toner on the photoconductor is removed and cleaning is performed.

Next, the carrier to which the toner has adhered is carried on the cleaning sleeve 32 by magnetic force and is conveyed while forming a magnetic brush. At a portion facing the roller 33, the roller 33 comes into contact with the roller 33, and at this time, the toner is electrostatically attached to the collection roller 33. Toner collection roller
Reference numeral 33 denotes an example of a toner collecting unit.A larger bias voltage is applied to the roller 33 on the negative side than the negative bias voltage applied to the cleaning sleeve 32. Only the charged toner moves to the toner collecting roller 33 side, and the negatively charged carrier remains on the cleaning sleeve 32. At that time, a certain amount of toner is left on the cleaning sleeve 32 side, and this becomes toner in the cleaning agent C. The toner collecting roller 33 rotates clockwise, and a collecting blade 34 made of an elastic rubber or an elastic metal plate or the like comes into contact with the roller 33. It will be scraped. The scraped toner is discharged out of the cleaning device by a discharging screw 35.

On the other hand, the cleaning agent C on the cleaning sleeve 32
Is further transported, and at the doctor blade section 36,
The thickness of the cleaning agent C is regulated to be, for example, about 0.5 to 2.0 mm, and the cleaning agent C enters the cleaning region X again.

The cleaning sleeve 32 and the toner collecting roller 33
Are rotatably supported by the back and front side plates of the cleaning case 40, and a cover 42 is attached to the upper opening of the case 40.

As described above, the toner remaining on the photoconductor 18 is recovered by the cleaning agent C carried on the cleaning sleeve 32, and the cleaned photoconductor 18 is used repeatedly.

The above-described doctor blade section 36 includes a photosensitive member 18 and a cleaning sleeve 32 so that proper cleaning is performed.
And a regulating means for regulating the amount of the cleaning agent conveyed to the cleaning area X between them.

By the way, in the cleaning device 27 as described above,
Of the toner that has migrated from the photoreceptor 18 to the cleaning sleeve 32 side, toner particles having a low charge amount and toner particles that have not been fully charged despite the charging action of the pre-cleaning charger 28 are separated from the cleaning sleeve 32. And may adhere to the photoreceptor again. In addition to the cleaning device 27, the developing devices 21Y and 21Y
Toner floating from M, 21C, 21B, etc., paper powder of transfer paper or additives contained therein adhere to the surface of the photoreceptor 18.
If the toner, paper powder, or the like thus attached is left as it is, there is a possibility that the toner, paper powder, or the like will adhere to the surface of the photoconductor in a thin film over time. This is the filming phenomenon described earlier,
When this occurs, the sensitivity of the photoreceptor 18 becomes uneven, and the density of the toner image formed on the surface thereof becomes uneven or the background becomes dirty. Therefore, it is necessary to remove the filming formed on the photoconductor at an early stage or to prevent the occurrence of the filming.

In the illustrated copying machine, the magnetic brush cleaning device 27 constitutes a filming removing device. That is, the latent image carrier filming removal apparatus of this embodiment includes an agent carrier comprising a cleaning sleeve 32 disposed opposite to the photosensitive member 18 which is an example of a latent image carrier on which a toner image is formed during image formation. A carrier having a carrier, in this example, a cleaning agent is conveyed to a region X between the latent image carrier and the agent carrier while the cleaning agent is carried on the agent carrier by magnetic force, and the conveyed agent is transferred to the latent image. The surface of the carrier is rubbed, whereby the filming removal operation of the latent image carrier is performed. At that time, a large amount of the agent is conveyed to the region X between the latent image carrier and the agent carrier in the magnetism other than during the image formation when a toner image is formed on the latent image carrier, compared to when the image is formed. The filming removal operation of the latent image carrier is performed.
That is, at a time other than the time of image formation for forming a toner image on the photoreceptor 18 as described above, a larger amount of cleaning agent is applied between the photoreceptor 18 and the cleaning sleeve 32 than during the normal photoreceptor cleaning operation. The photosensitive member 18 is operated in a state where a larger amount of the cleaning agent C is packed in this area X than during the cleaning operation.
In this way, the cleaning agent is accumulated in the cleaning region X, and the particles of the carrier in the cleaning agent C are strongly rubbed against the surface of the rotating photoreceptor 18, so that the above-described film formed on the photoreceptor surface is formed. You can scrape the mining. As described above, the filming removing operation can be performed to remove the filming on the photoreceptor 18 or prevent the occurrence of the filming.

In the cleaning device that transports the cleaning agent C on the sleeve 32 by fixing the magnet 31 and rotating the cleaning sleeve 32 as in the illustrated cleaning device 27, the cleaning area X is removed to remove filming as described above. To increase the amount of the cleaning agent C supplied to the cleaning sleeve 32, for example,
May be made slower than during the normal cleaning operation. If the linear speed of the cleaning sleeve 32 becomes slow,
The centrifugal force acting on the cleaning agent C carried thereon is weakened, and the cleaning agent C is strongly attracted to the surface of the cleaning sleeve 32. As a result, the amount of the cleaning agent C passing through the doctor blade 36 increases, and the amount of the cleaning agent C conveyed to the cleaning area X increases.

When performing the filming removing operation as described above, the rotation speed of the cleaning sleeve 32 may be always lower than that in the normal cleaning operation, but the low speed and the high speed may be repeated. Alternatively, the cleaning sleeve may be stopped while the photoconductor 18 is being rotated, the cleaning agent C may be retained in the cleaning area X, or the rotation and the stop of the cleaning sleeve may be repeatedly performed. There is no difference from the proposal.

As described above, the filming on the photoreceptor 18 can be removed by using the cleaning agent C or its occurrence can be prevented beforehand. However, such an effect of the filming removal is caused by the particles of the carrier of the cleaning agent C used. The result of the experiment revealed that it depends on the diameter. That is, when the particle size of the carrier is smaller than that of the carrier, the filming removal effect can be enhanced.
Under the following conditions, the filming removal effect can be significantly improved. From such a viewpoint, in the filming removing apparatus of this example, the particle size of the carrier particles of the agent is set to 50 μm or less.

FIG. 3 is a graph showing an example of the relationship between the particle diameter of the carrier particles and the filming removability. It can be clearly understood from this graph that the filming removability is sharply increased when the particle diameter is 50 μm or less. 50μm carrier particle size
It is considered that the smaller the value is, the higher the density of the cleaning agent C is, and the more the cleaning agent is pressed against the surface of the photoreceptor 18, so that the effect of removing filming is improved. FIG. 4 shows the relationship between the particle size of the carrier and the load torque of the photoreceptor 18. When the particle size is 50 μm or less, the load torque of the photoreceptor sharply increases. From this, it can be understood that when the particle diameter of the carrier is 50 μm or less, the pressure contact effect between the cleaning agent C and the photoconductor is enhanced.

When the shape of the carrier particles is not spherical but irregular, that is, angular, the effect of removing filming can be further enhanced. For this reason, in the filming removing apparatus of the present example, an amorphous carrier is used as another carrier particle.

In the above description, the cleaning sleeve 32 of the cleaning device 27 is taken as an example of the image carrier, the cleaning agent C is carried on the cleaning sleeve 32, and the filming on the photoreceptor 18 is removed by using the cleaning agent C. However, like the developing devices 21Y, 21M, 21C, and 21B illustrated in FIG. 1, a developing sleeve 50Y, 50M, 50C, and 50B that carries and conveys a developer composed of a mixed powder of a toner and a carrier by magnetic force is provided. When the developing device is used, filming of the photoreceptor can be removed in exactly the same manner as described above.

For example, during image formation or other filming removing operations, the developing sleeves 50Y, 50M, 50
At least one of C and 50B is rotated at a low speed to increase the amount of agent passing through a doctor blade 51 which is an example of a regulating means. In this example, the developer is transported to remove the filming of the photoconductor 18. Also in this case, by using a developer having a carrier having a particle diameter of 50 μm or less, the effect of removing filming can be further enhanced.

It goes without saying that each of the above-described configurations using the cleaning device or the developing device can be employed in a single-color copying machine having only one developing device.

In each of the specific examples described above, the example in which the cleaning sleeve 32 or the developing sleeve is driven to rotate and the magnet provided therein is fixed, but the cleaning sleeve or the developing sleeve is fixed as is well known per se. The cleaning agent C or the developer can be conveyed by rotating the magnet inside or rotating both the magnet and the sleeve, and the present invention can be applied to such a case without any trouble.
That is, also in this case, at the time of the filming removing operation, for example, the rotation of the magnet or the sleeve is reduced, and the amount of the cleaning agent C or the developer conveyed to the area between the sleeve and the photosensitive member 18 is increased.

The present invention can be applied to a monochrome copying machine or various image forming apparatuses other than the copying machine, and can also be applied to a case where the latent image carrier is a belt-shaped one or a case where the agent carrier is a belt-shaped one. .

〔The invention's effect〕

According to the present invention, the filming on the latent image carrier can be more effectively removed at low cost than in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a copying machine to which the present invention is applied.
FIG. 2 is an enlarged cross-sectional view of the magnetic brush cleaning device, FIG. 3 is a graph showing the relationship between the particle size of the carrier and filming removability, and FIG. 4 is a diagram showing the relationship between the particle size of the carrier and the load torque of the photoconductor. It is a graph. X ... area

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-202474 (JP, A) JP-A-59-55468 (JP, A) JP-A-62-226173 (JP, A) 85879 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 15/08-15/08 507 G03G 15/09-15/09 101

Claims (1)

(57) [Claims] An image forming apparatus has an agent carrier disposed opposite to a latent image carrier on which a toner image is formed at the time of image formation, and carries an agent having a carrier on the agent carrier by a magnetic force. A toner image is formed on the latent image carrier in a latent image carrier filming removal device that transports the transported agent to the region between the body and the agent carrier and rubs the transported agent against the surface of the latent image carrier. At a time other than at the time of image formation, a larger amount of agent than at the time of image formation is transported to an area between the latent image carrier and the agent carrier, and the filming removal operation of the latent image carrier is performed. A filming removal apparatus, wherein amorphous carrier particles are used as carrier particles of the agent, and the particle size of the carrier particles is 50 μm or less.