JP2632043B2 - Cleaning device for image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object 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 the same printer, and particularly to a cleaning apparatus for the image forming apparatus. .

(Prior art and problems to be solved) The transferable toner image formed on the surface of the running image carrier is
In a known image forming apparatus that repeats a process of transferring to a transfer material mainly composed of paper, a residual toner remaining on an image carrier without being transferred to a transfer material or a fine particle generated from paper as a transfer material is used for each transfer. It is indispensable to sufficiently remove foreign matter and the like adhered to the image carrier due to fine paper dust, corona products caused by the presence of the high-pressure member in the apparatus, and the like.

When a magnetic toner is used as a means for cleaning these unnecessary substances, a cleaning blade made of an elastic material such as rubber is used to remove the toner, and the image carrier is used as a means for removing foreign substances such as the latter. There has already been proposed an arrangement in which a magnet roller that moves relative to each other is provided, and a magnetic brush is formed by the collected toner, thereby rubbing the surface of the image carrier.

The cleaning blade is extremely effective in removing toner. Particularly when one-component magnetic toner is used as a developer, special magnetic particles for forming a magnetic brush are prepared on the above-described magnet roller. There is no necessity, and the toner forming the brush is supplied one by one. Therefore, there is no need to consider the deterioration due to use, and further, the toner is supplied to the contact portion of the cleaning blade with the image carrier. It has various advantages such as stabilizing the contact state of the blade and maintaining a good cleaning function for a long period of time by exerting the action as a lubricant. As it has realized, it has achieved a certain effect.

By the way, it is well known that image forming apparatuses capable of multi-color copying and color copying are gradually becoming popular in recent years, but the color toner used for the purpose is to use a colorless resin such as a dye or a pigment in order to sharpen the color. It is usually non-magnetic because it is composed by mixing.

On the other hand, even in a device capable of color copying, it is common to require a black toner for color adjustment,
Considering that the current situation is that a black image is occupied by a considerable proportion, it is of course impossible to eliminate the black toner, and it is not only an image forming process but also a cleaning means. Considering the functions of the peripheral members, it is practically possible to immediately eliminate the above-mentioned advantages by using a one-component magnetic toner as the black toner and disposing the above-described magnet roller in the cleaning device. Should be impossible.

Assuming such a situation, in the above-described cleaning device in the image forming apparatus capable of performing color copying, the magnetic toner and the non-magnetic toner must be used in common.

In such an apparatus, if the non-magnetic toner is used continuously, the non-magnetic toner is not caught by the magnet roller, so that the magnetic brush on the roller is covered with the non-magnetic toner, and the image of the image due to dropping of the toner is removed. This can lead to contamination and cabin contamination.

The present invention has been made in order to cope with such a situation, and in a cleaning device of an image forming apparatus in which a magnetic toner and a non-magnetic toner are used in common, both of them can be sufficiently removed, and a stable cleaning function is provided at all times. It is an object of the present invention to provide a cleaning device capable of maintaining the above condition.

(2) Configuration of the Invention (Technical Means for Solving the Problems and Their Functions) In order to achieve the above object, the present invention provides an image forming apparatus that selectively uses a magnetic toner and a non-magnetic toner. In a cleaning apparatus comprising: a cleaning blade for removing residual toner on an image carrier; and a magnet roller forming a magnetic brush on the surface of the image carrier, a non-magnetic toner is used in proximity to the magnet roller. The cleaning device (1) provided with a bias applying means for applying a bias having a polarity opposite to the charging polarity of the toner only at the time, or in the above (1), the bias applying means is in a roller shape. In the cleaning device (2) or any one of the above (1) and (2), the bias applying means is a magnetic brush of a magnet roller. The cleaning device (3) is a thickness regulating means.

With this configuration, the magnetic brush formed on the magnet roller is covered with the non-magnetic toner, and the non-magnetic toner is dripped off. Can be prevented from being contaminated.

FIG. 1 is a sectional side view of a cleaning device according to an embodiment of the present invention. The cleaning device has an axis perpendicular to the sheet of FIG.
A cleaning device 2 is disposed in parallel with the cylindrical photoreceptor 1 rotating and running in the direction of rotation, and one edge of one end line of the cleaning blade 3 attached to the cleaning device 2 is the photosensitive member. When the residual toner or the like remaining on the photoreceptor arrives at the position of the blade 3 with the rotation of the photoreceptor 1 without being transferred to the transfer material at a transfer portion (not shown), it is scraped off by this. Shall be.

On the upstream side of the blade when viewed in the running direction of the photoconductor 1, a magnet roller 4 that rotates in the direction of arrow B and has a rubbing portion formed at a distance δ from the surface of the photoconductor is provided. A magnet roller 4 is provided downstream of the rubbing portion.
And a regulating member 5 for regulating the height of the magnetic brush at a distance α.

Further, a bias roller 6 rotating in the direction of arrow C is disposed downstream of the regulating member at a distance β from the magnet roller 4, and the power supply 9 charges the non-magnetic toner to the roller 6. It is assumed that a bias voltage having a polarity opposite to the polarity is applied.

In the figure, reference numeral 7 denotes a scraper for removing toner adhering to the bias roller 6, and reference numeral 8 denotes a transport screw for transporting the collected toner and the like to a waste toner container or the like.

The gap β is set so that the bias roller 6 does not touch the magnetic brush formed by the regulating member 5 to break the magnetic brush. It is set appropriately so as to contact and rub against one surface.

FIG. 2 is an enlarged view of a main portion schematically showing the absence of toner shake in a portion near the magnet roller of the above-described apparatus, wherein reference numeral 11 denotes magnetic toner, and reference numeral 10 denotes non-magnetic toner. And

In a normal state, about 200 layers of magnetic toner are piled up around the magnet roller, and this rubs against the surface of the photoreceptor to exert a cleaning action.

When the non-magnetic toner arrives at such a state, the non-magnetic toner is mixed with the magnetic toner and gradually covers the magnetic toner, and is sequentially conveyed to the magnet roller 4 to reach the vicinity of the bias roller 6.

As described above, since a bias voltage having a polarity opposite to that of the non-magnetic toner is applied to the bias roller 6, the non-magnetic toner is attracted and removed by the roller 6 at this position, and further scraped by the scraper 7. It is dropped and falls on the transport screw 8.

Therefore, thereafter, the magnetic brush reaches the rubbing portion facing the photoreceptor in a state where the nonmagnetic toner is not mixed with the magnetic brush, thereby performing good cleaning.

 Hereinafter, experimental examples will be described.

Using amorphous silicon photoconductor as photoconductor,
This was driven at a peripheral speed of 330 mm / sec. The magnet roller has a 6-pole configuration, and the magnetic flux density at the magnetic pole position is 1000
Gauss, outer diameter 20 mm, peripheral speed 260 mm / sec, bias roller 12 mm outer diameter, peripheral speed 100 mm / sec.

The aforementioned gap δ was set to 1.0 mm, α was set to 1.30 mm, and β was set to 1.40 mm.

As the toner, a black magnetic toner and a red non-magnetic toner having an average particle size of about 10 μm were used.

The voltage applied to the bay-eye roller 6 was set to +500 V, and when a document with a printing rate of 20% was continuously copied, after 30,000 copies, the surface of the magnetic brush was slightly covered with non-magnetic toner but dropped. It was confirmed that there was no in-flight scattering and no image contamination.

Next, an experiment was conducted under the same conditions as described above except that the bias roller was not provided. As a result, 10,000 to 15,000 sheets of non-magnetic toner were scattered in the machine and dropped onto copy paper.

The bias voltage to the bias roller is preferably +500 to 1000 V. If it is less than +300 V, the nonmagnetic toner is not sufficiently captured, and if it exceeds +1000 V, a part of the magnetic toner tends to be peeled off, which is inconvenient.

FIG. 3 shows another embodiment of the present invention, in which parts corresponding to those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this device, the rotation direction was the opposite direction to that described above, and the peripheral speed was 100 mm / sec.

The bias roller 12 is disposed below the magnet roller 4 in the drawing and has a peripheral speed of 100 mm / sec. The roller also acts as a regulating member for regulating the height of the magnetic brush formed on the surface of the magnet roller. I tried to play.

The distance between the photoconductor 1 and the magnet roller 4 is 1.0 mm, and the distance between the magnet roller 4 and the bias roller 12 is 1.30 mm.
As a result, the same experiment as above was carried out, and similarly satisfactory results were obtained.

FIG. 4 is a view of the apparatus shown in FIG. 1 in which the regulating member is removed and the bias roller 12 is disposed at the position, so that the bias roller regulates the thickness of the magnetic brush. is there.

With such a configuration, the same result as that of the apparatus of each of the above embodiments can be obtained.

FIG. 5 shows still another embodiment of the present invention, the basic configuration of which is the same as that of the apparatus shown in FIG.
Parts corresponding to those of the apparatus are denoted by the same reference numerals.

In the illustrated device, a stirring member 14 extending in the longitudinal direction of each roller is disposed at an appropriate position in the space between the magnet roller 4 and the bias roller 6, thereby forming the stirring member 14 on the surface of the magnet roller 4. The magnetic brush is slightly disturbed and tends to rise.

For this reason, since the magnetic toner is basically constrained by the magnet roller, it is stable after passing through the agitating member without dropping, but the magnetic toner does not fall on the non-magnetic toner captured in the magnetic brush. The restraining action is weakened, and it is easy for the bias roller 6 to catch the light.

In each of the embodiments described above, the application of the bias voltage to the bias roller is turned off when the magnetic toner is used, and turned on only when the non-magnetic toner is used. If the magnetic toner is peeled off more than necessary by the bias roller, It is preferable because the shortage of toner during the operation can be prevented.

(3) Effects of the Invention As described above, according to the present invention, there is provided an image forming apparatus for selectively using a magnetic toner and a non-magnetic toner, and a residual toner using a cleaning blade and a magnet roller. In a cleaning device for removing
When using a non-magnetic toner that is not easily magnetically constrained by the magnet roller, a bias having a polarity opposite to that of the toner is applied. Therefore, while maintaining the advantage of using the magnet roller as a cleaning member, the non-magnetic toner is This has a remarkable effect in favorably eliminating deterioration of the cleaning function due to its use and obtaining a high-quality image.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a cleaning device showing an embodiment of the present invention, FIG. 2 is a schematic diagram for explaining the behavior of toner in the cleaning device, and FIG. 3, FIG. 4, and FIG. It is a principal part side view which shows other Example of this. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 2 ... Cleaning device, 3 ... Cleaning blade, 4 ... Magnet roller, 5 ... Regulatory member, 6 ... Bias roller.

Claims (3)

(57) [Claims] An image forming apparatus selectively using a magnetic toner and a non-magnetic toner, comprising: a cleaning blade for removing residual toner on an image carrier; and a magnetic blade for rubbing the image carrier on a surface. A cleaning device including a magnet roller that forms a brush, wherein a bias applying unit that applies a bias having a polarity opposite to the charging polarity of the toner only when non-magnetic toner is used is disposed in proximity to the magnet roller. Become a cleaning device. 2. A cleaning apparatus according to claim 1, wherein said bias applying means is in the form of a roller. 3. The cleaning device according to claim 1, wherein the bias applying means is a thickness regulating means for a magnetic brush of the magnet roller.