JPH02143287A - Cleaning device - Google Patents

Abstract

PURPOSE:To reduce the ratio of the waste toner to nonmagnetic toner on the surface of a magnet roller sop as to prevent scattering of the nonmagnetic toner by resupplying by circulation the magnetic toner removed in the course of cleaning operations to the magnet roller of a cleaning device. CONSTITUTION:A toner separating device 7 for separating magnetic toner and nonmagnetic toner from the toner discharged from a cleaning device 6 and carrying device 8 which resupplies the magnetic toner of the device 6 are provided. As the magnetic and nonmagnetic toner are supplied by means of developing devices 2 and 3, part of the magnetic toner is caught by a magnet roller 22. While the caught magnetic toner dropping down through a collecting pipe 46 is sent to a carrying device 8, the quantity of the sent toner is small and most of the magnetic toner overflows the upper opening 12 of the pipe 46 and are collected in a toner collecting box 9b. Then the magnetic toner is resupplied into the device 6 by means of carrying devices 26 and 27. In addition, this device is provided with the pipe 26 incorporating the screw 27 passing through the pipe 26 and the magnetic toner is resupplied to the roller 22. Therefore, scattering of the nonmagnetic toner can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer thereof, and a cleaning apparatus therefor.

[Conventional technology]

In a well-known image forming apparatus that repeats the process of electrostatically transferring a toner image electrostatically formed on the surface of an image carrier onto a transfer material such as paper, the toner image does not contribute to the transfer during transfer and is It is necessary to thoroughly clean the residual toner that remains on the body each time, and the conventional cleaning method for this purpose is to remove the residual toner by pressing a cleaning blade made of an elastic material such as urethane rubber against the surface of the image carrier. Something like this is already in widespread use.

Furthermore, the surface of the image carrier is not only contaminated with residual toner, but also with fine paper dust generated from paper, which is most commonly used as a transfer material, precipitated organic substances, and corona caused by the presence of high-pressure members in the device. It is also necessary to remove various foreign substances such as products that may adhere to the image carrier and cause deterioration of image quality, but such foreign substances cannot be sufficiently removed by the cleaning blade. Sometimes.

For this reason, especially in the case of an image forming apparatus that uses one-component magnetic toner, a magnetic roller is installed in the vicinity of the cleaning blade, and once the collected toner is used to form a magnetic brush on the magnetic roller, the toner is again image-bearing. A method has been proposed in which the various foreign substances mentioned above are removed by rubbing against the body.

In addition to the action of removing foreign matter, such a means also supplies toner little by little to the edge of the blade to prevent the blade from turning over even when there is no toner on the surface of the image carrier. It also has the advantage of applying mechanical force to the toner that electrostatically adheres to the surface of the image carrier, reducing the adhesion force to the image carrier and making it easier to remove with a blade. It has achieved certain effects in one-component magnetic toners used to obtain black images.

Incidentally, in recent years, in addition to developing devices containing toner for obtaining black images, at least one developing device containing color toner has been developed. (Image forming apparatuses that are equipped with 11 developing devices and obtain multicolor images by selectively using these developing devices have come into use.

The color toner used in such devices is usually made of transparent resin mixed with dyes, pigments, etc. in order to make the colors of the copied image clearer, and the toner is non-magnetic. When this color toner is applied to an image forming apparatus that uses a cleaning device having a magnetic roller as described above, problems with the cleaning function cannot be avoided because the color toner is not attracted to the magnetic roller. .

In order to adapt the cleaning action to non-magnetic toner, eliminating the magnetic roller and relying only on the cleaning blade is advantageous, as described above, and also when using color toner. Even with such an image forming apparatus, it is not advantageous to immediately throw away the advantages of using a magnetic roller, since black images are usually obtained frequently, and it is well assumed that the black images are the thickest. Needless to say, the present applicant has previously proposed an image forming apparatus in which magnetic toner is supplied from a developing device to a cleaning device based on information that an image has been formed using non-magnetic toner. It had been done.

[Problem that the invention is trying to solve] However,
In the above-mentioned conventional example, the magnetic toner for cleaning is consumed and reduced by passing through the non-image area of the image bearing member, which may hinder the subsequent cleaning operation or cause image formation using non-magnetic toner. However, the magnetic toner may be consumed.

[Means for solving problems]

In the present invention, the magnetic toner removed by cleaning in the cleaning device is circulated and re-supplied to the Macnet roller of the cleaning device.

〔Example〕

FIG. 1 is a schematic side view of the main parts of an embodiment in which the present invention is applied to an image forming apparatus equipped with a rotating cylindrical photoreceptor. The cleaning device includes a first developing device 2 that stores non-magnetic color toner and carrier, and a first developing device 2 that stores component-based magnetic toner, which is located close to a photoreceptor 1 that extends perpendicular to the plane of the paper and rotates in the direction of the arrow. Two developing units 3 are provided. These are displaced by a control mechanism (not shown) in the direction of the arrow X shown in the figure, so that one of them assumes an operating position close to the photoreceptor, while the other developer retreats to an inoperative position away from the photoreceptor. It is assumed that

When the electrostatic latent image formed on the surface of the photoreceptor 1 reaches a position facing a developing device located close to the electrostatic latent image, toner is supplied from the developing device and the latent image is visualized.

Thereafter, when the visualized toner image reaches the transfer site where the transfer charger 5 is located, a transfer material (not shown) that advances from the conveyance path 4 in synchronization with the toner image
contacts the photoreceptor, the toner image is transferred to the transfer material, and the transfer material is further separated from the photoreceptor and conveyed to a fixing site (not shown).

On the other hand, residual toner that is not transferred to the transfer material during transfer and remains on the photoreceptor 1 reaches the cleaning device 6 as the photoreceptor rotates and is removed from the photoreceptor l.

Needless to say, a charger, an image signal applying means, a pre-discharge lamp, and other members necessary for image formation are arranged around the photoreceptor 1, but these are not directly related to the present invention. Since there is no such thing, I have omitted everything.

Further, 7 is a toner separation device for separating magnetic toner and non-magnetic toner from the toner discharged from the cleaning device 6, 8 is a conveying device for re-supplying the magnetic toner to the cleaning device, and 9 is a waste toner ( box) indicating in this case the toner to be discarded.

FIG. 2 is a cross-sectional view showing the configuration of the cleaning device 6, in which one edge of one end of the cleaning blade attached to the casing is pressed against the surface of the photoreceptor 1, and a transfer area (not shown) is Scrape off any residual toner generated.

A magnet roller 22 is disposed on the upstream side of the cleaning blade 21 when viewed in the traveling direction of the photoreceptor, and is rotated in the direction of the illustrated arrow by an appropriate drive source (not shown).

As magnetic toner and non-magnetic toner are supplied by the developing devices 2 and 3, some of the magnetic toner is transferred to the magnetic roller 2.
2, a toner layer with a constant thickness determined by the regulating roller 23 is formed on the surface of the toner layer, and as the roller 22 rotates, the toner layer reaches a position facing the photoconductor l, and the toner layer slides on the photoconductor surface. It shall be rubbed.

In order to ensure that the toner layer rubs the surface of the photoreceptor,
The thickness of the toner layer formed by the regulating roller 23 is
It goes without saying that the distance between the photoreceptor 1 and the magnet roller 22 is appropriately larger than the minimum distance, and 24 is a scraper for the regulating roller 23.

It is assumed that the toner overflows from the toner pool formed by the regulating roller 23 and the scraper 4 and is further discharged to the outside by the conveyance screw 25. Reference numeral 26 denotes a pipe and screw for resupplying magnetic toner, and the cylindrical pipe 26 is disposed parallel to the longitudinal direction of the cleaning device 6, with a screw 27 passing through it. A perspective view of the toner resupply pipe 26 and screw 27 is shown in FIG. Reference numeral 28 denotes a hole drilled in this pipe, which is designed to allow the magnetic toner to fall uniformly in the longitudinal direction.

Next, the cleaning device 6.7.8°9. shown in FIG.
10, its operation and movement of toner will be explained in more detail. The mixture of magnetic toner, non-magnetic toner, and paper powder discharged from the cleaning device 6 is
The toner passes through a magnetic toner separation device 7 and is separated into magnetic toner, non-magnetic toner, and paper powder.

FIG. 4 is a diagram for explaining the magnetic toner separation device No. 7. In the illustrated device, a non-magnetic cylinder 41 is fixedly provided, and a magnetic roller 42 is rotatably provided inside. The magnetic roller 42 is arranged with alternately different magnetic poles. An introduction pipe 43 is provided on the non-magnetic cylindrical sleeve 41 to introduce the magnetic developer removed from the cleaning means into the apparatus.

On the other hand, in order to discharge the non-magnetic toner C from the developer,
A collection pipe 44 is disposed substantially below the right end of the sleeve 41 in the figure, and this collection pipe 44 is connected to the waste toner collection box 9. Furthermore, a scraper 45 for separating the developer from the sleeve 41 after removing the non-magnetic toner is provided on the sleeve 41.
A recovery pipe 46 is disposed below, and below it, a recovery pipe 46 is disposed to recover the falling developer while conveying it to a portion of the conveyance screw 8 . In the above-described device, the developer Dc removed by the cleaning means is guided from the arrow B, and the developer Dc is guided from the arrow B to the sleeve 4.
Fall on top of 1. A magnetic roller is rotated in one direction,
As described above, the magnetic developer moves in the r direction opposite to its rotation. As the toner moves, the non-magnetic toner C becomes easily separated, so that the non-magnetic toner C falls due to the action of gravity and the airflow at the right end of the sleeve in the figure, and is collected in the collection tube 44.

The magnetic developer Ds is separated by a scraper 45 and sent to a collection tube 4.
6 to the conveying pipe 8. Further, as shown in FIG. 1, a fan 10 and a filter 11 are attached to the waste toner box 9(a), and air flows in the direction of arrow a through an intake port 12, separating non-magnetic toner from magnetic toner. Its role is to peel it off. The waste toner box 9 is divided into two chambers, 9(a) and 9(b), with non-magnetic toner being stored on the 9(a) side and 9-(b).
Magnetic toner is collected on the side. The magnetic toner that has fallen down the collection tube 46 is sent to the conveyance device 8, but the amount of toner conveyed by the conveyance device 8 is small, and much of the magnetic toner overflows from the upper opening 12 of the vibrator and is sent to the magnetic toner collection box 9 ( b).

Further, the conveying device 8 sends the magnetic toner in the directions of arrows 26 and 27, and returns it to the cleaning device 6.
transported by. The conveying devices 26 and 27 have the configuration shown earlier in FIG.
2, magnetic toner is supplied again.

[Other Embodiments] In the embodiments described above, there are many possible means for separating and collecting the magnetic toner and non-magnetic toner in addition to those described in the embodiments described above. FIG. 5 shows an example in which electric attraction force is used as the separation and collection means.

First, a high voltage of about IKV is applied between the conductive cylinder 51 rotating in the direction of the arrow and the sleeve 11, and only non-magnetic toner adheres to the rotating cylinder 51 and is scraped by the scraper 52. Fall due to gravity.

Although this method is slightly less efficient than the method using electric current, it is effective in simplifying the equipment.

Furthermore, in the above embodiment, only the magnetic toner is separated and collected from the mixed magnetic and non-magnetic waste toner discharged from the cleaning device, and then re-supplied to the cleaning device. A configuration in which the separation step is omitted is also sufficient. That is, the present applicant has previously proposed providing a toner accumulation portion (toner reservoir) in the magnetic roller, and it has been described that this toner reservoir suppresses the scattering of non-magnetic toner. In FIG. 2, this toner pool is a toner pool indicated by T formed by the regulating roller 23 and the scraper 24. If this toner reservoir is made large, even if non-magnetic toner is continuously sent to the cleaning device, the ratio (non-magnetic toner M/amount of magnetic toner) does not increase and scattering can be suppressed. However, it is difficult to provide such a large toner reservoir inside the cleaning device, and the temperature inside the cleaning device is high, making it easy for toner to deteriorate.
It may be impossible to make the toner reservoir thick. Therefore, it is sufficient to provide a large toner reservoir outside the cleaning device η and to supply waste toner into the cleaning device again. .

An example is shown in Figure 6. First, in the figure, 176
There is a toner box 61, a feed screw 62, and a magnetic belt 63 for collecting toner and rotating in the direction of the arrow. Further, this belt is covered with a non-magnetic member 64 to prevent toner from entering.

Further, the scraper 65 is a conveying screw. As a result, the toner discharged from the cleaning device 6 is sent to the lifting belt 1 by the screw 62, lifted up by the lifting belt 1, scraped by the scraper 65, and transferred into the cleaning device 6 by the conveying screw 66. In addition, the cleaning device 6
As shown in Figure 2, this waste toner box 6I contains a certain amount of waste toner from the beginning, and this waste toner box serves as a toner reservoir. .

〔Effect of the invention〕

As explained above, by supplying the waste toner discharged from the cleaning device to the cleaning device again, it is possible to reduce the ratio of non-magnetic toner in the waste toner on the surface of the magnet roller of the cleaning device. It is possible to prevent toner from scattering.

Furthermore, since the magnetic toner in the developing device is not consumed for cleaning, running costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the outline of the cleaning device of the present invention, Fig. 2 is an internal view of the cleaning device, Fig. 3 is a perspective view of the waste toner supply section, and Fig. 4 is a diagram of the magnetic toner separation device. Figure 5 is a diagram of another example of the magnetic toner separation device, Figure 6 is an explanation of another embodiment. Drum cleaning device Magnetic toner separation device Magnetic toner transport section Waste toner box Cleaning blade Magnet roller Regulatory roller Scraper Screw Toner supply pipe Screw opening sleeve Magnet roller Introduction tube Non-magnetic toner collection tube Scraper Magnetic toner collection tube Rotating cylindrical electrode Scraper No. 3 figure

Claims (1)

[Scope of Claims] A cleaning device equipped with a magnet roller having a magnetic brush formed on its surface as a cleaning means for removing residual toner from an image bearing member in an image forming apparatus that forms an image using magnetic toner, comprising: A cleaning device characterized in that magnetic toner that has been cleaned and removed is used in circulation.