JPH07168500A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the transfer irregularity by removing a foreign matter such as a toner aggregation body and a carrier sticking on the image carrier with the simple constitution in the image forming device capable of visualizing the electrostatic latent image on the image carrier by the adherence of the toner with use of the two-component developer. CONSTITUTION:The foreign matter recovering member 13 provided with plural magnetic poles inside the cylindrical member is arranged closely to the image carrier 1 in the cleaning device 7 and the bias voltage having the polarity direction for attracting the toner aggregation body is impressed from the aggregation toner recovering bias power source 15 and 16. Thus, even though the foreign matter is transited onto the image carrier at the time of developing, the toner aggregation body applied with the electric charge in the bias electric field is transited to the foreign matter recovering member 13, and moreover, the carrier too is attracted by the attracting force of the magnetic pole. Moreover, by disposing the foreign matter recovering member 13 in the cleaning device 7, the recovering device for transporting and storing the foreign matter can be shared by use for the remaining toner recovering device, hence the maintenance care is made easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used in electrophotographic copying machines, facsimiles, laser printers, etc., and more specifically, a two-component developer containing a non-magnetic toner and a magnetic carrier. The present invention relates to an image forming apparatus that visualizes an electrostatic latent image on an image carrier by adhering toner.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus using a two-component developer to visualize an electrostatic latent image on an image holding member by adhering toner, for example, an image forming apparatus in a developing device is placed close to or opposite to the image holding member. It is known that a developing roller is provided, a magnetic brush of a two-component developer is formed on the developing roller, and non-magnetic toner in the magnetic brush is caused to fly to an electrostatic latent image in a bias electric field to perform development. Has been. In such an image forming apparatus,
Toner agglomerates mixed in the toner in the developing device, magnetic carriers that have a low magnetic force and a small attraction force with the developing roll, are mixed with the non-magnetic toner in the developing process and transferred to the electrostatic latent image on the image carrier. It may happen. As described above, when foreign matter larger than the toner is mixed with the toner particles forming the toner image and adheres to the surface of the image holding body, the large foreign matter makes uniform contact between the transfer paper and the image holding body in the transfer process. Interfering, and the transfer of the peripheral portion around the portion where the foreign matter was present becomes insufficient. Therefore, there is a problem that so-called transfer omission occurs in the image on the transfer paper.

Such a phenomenon is relatively unnoticeable in a black-and-white copying machine because there are many line images, but in a color copying machine, black, magenta, cyan, and yellow are printed on the same sheet of paper.
Since the colors are transferred in an overlapping manner, even if the number of foreign matters adhered to the surface of the image carrier in the one-color developing process is small, four times as many transfer strokes will eventually occur on the transfer paper. It becomes a big problem above. Further, in a color copying machine, even a slight transfer omission causes a difference in hue on a paper image after transfer, which is easily noticeable, and improvement in particular is desired.

On the other hand, as another image forming apparatus for forming a color image, there is also known an apparatus for forming a color image on a sheet in a single transfer process by superposing toner images of a plurality of colors on an image carrier. Has been. Such an apparatus has an advantage that a complicated transfer drum is not required and that toner images of four colors are relatively easily superposed, and is an apparatus advantageous for downsizing of a color apparatus. is there. However, in such an image forming apparatus, in the image forming process,
Since the superimposed toner images are collectively transferred, if foreign matter adheres to the surface of the image carrier as described above, the image information of four colors will be lost at that portion at the same time. As a result, so-called white spots occur on the image, resulting in significant image defects. Therefore, particularly strong improvement is desired.

In order to eliminate the above-mentioned transfer defects and white spots, a technique for preventing the generation of toner aggregates in the developing device and a technique for preventing the carrier from transferring to the image carrier. Although it is preferable to develop the above, it is extremely difficult in reality and a small amount of toner aggregates or carriers in the developing device adhere to the surface of the image carrier. Therefore, as an image forming apparatus configured to remove foreign matter adhering to the surface of the image carrier before the transfer step after forming the toner image, for example, Japanese Patent Laid-Open No. 63-2160.
The devices disclosed in Japanese Patent Laid-Open No. 72-72, and Japanese Patent Laid-Open No. 61-200561 are proposed.

The apparatus disclosed in Japanese Patent Laid-Open No. 63-216072 is provided with a magnetic carrier collecting device having a magnet roll on the downstream side of the developing device in the rotation direction of the image carrier and the surface of the image carrier is provided. The carrier adhered in the toner image is collected in the collecting device by magnetic force.

Further, in the apparatus disclosed in Japanese Patent Laid-Open No. 61-200561, a carrier collecting member made of a non-magnetic conductive material is arranged in the rear of the developing area in the developing device, in proximity to the surface of the image carrier. A bias voltage in the direction of attracting the carrier is applied from the bias power source to the carrier collecting member to collect the carrier adhering to the surface of the image carrier into the developing device.

[0008]

However, the above-mentioned image forming apparatus has the following problems. In the device disclosed in Japanese Patent Laid-Open No. 63-216072, it is necessary to dispose a dedicated container for storing the collected developer such as magnetic carrier, and when the container is full, a dedicated container for cleaning or replacement is required. There is a problem that maintenance work is required.

On the other hand, in the apparatus disclosed in Japanese Patent Laid-Open No. 61-200561, a magnetic carrier recovery device is integrally formed with the developing device so that the magnetic carrier and the like can be returned to the developing device. Although it has an advantage that the maintenance work can be avoided, foreign matter often enters the developing device, and this foreign matter may cause transfer failure. Further, in a color copying machine or the like having a four-color developing device, there is a problem that the entire device becomes complicated and large, resulting in cost increase.

Further, the devices disclosed in the above-mentioned JP-A-63-216072 and JP-A-61-200561 are
All of them are intended to remove the magnetic carrier in the toner image, and therefore foreign matters such as toner aggregates mixed in the toner image cannot be effectively removed, and still image quality deterioration such as transfer omission cannot be avoided. There is.

On the other hand, in an image forming apparatus for forming a color image by superposing colors on an image carrier, an elastic blade is used as a cleaning device provided in the apparatus because of its advantages of simple structure, small size and low cost. Is desirable. However, apart from the above-mentioned problems, conventionally, there have been problems to be solved in this elastic blade method. Specifically, in the case of making successive copies with a small image area, the amount of residual toner on the image carrier is reduced, the lubrication effect of the toner on the blade contacting part is reduced, and the blade tip is clogged. Or the paper dust or the like is trapped and damages the surface of the image carrier, resulting in defective cleaning.

To solve this problem, Japanese Patent Publication No. 2-1480
In the image forming apparatuses described in Japanese Patent Publication No. 84 and Japanese Patent Publication No. 44388/1990, a toner band (belt-shaped solid image) is positively created by a developing device, and this toner is used as a lubricant for a blade contact portion in a cleaning process. A device used as is proposed. However, although such a device is effective in preventing cleaning failure, it has a drawback that the running cost increases because the toner consumption increases.
Other solutions are desired.

The present invention has been made in view of the above problems, and an object thereof is to make an image carrier with a simple structure without increasing the size of an image forming apparatus or requiring dedicated maintenance work. Foreign matter such as toner agglomerates and carriers attached to the toner is collected before transfer to prevent transfer unevenness, or to prevent defective cleaning without increasing toner consumption.

[0014]

In order to solve the above problems, the invention according to claim 1 provides an image carrier capable of carrying a latent image due to a difference in charging potential, and the image carrier. An image exposure device that irradiates an image light to form a latent image; a developing device that uses a two-component developer containing a magnetic carrier and a non-magnetic toner to visualize the non-magnetic toner by adhering the non-magnetic toner to the latent image; An image forming apparatus having a transfer device for transferring a toner image on an image carrier to a transfer material, and a cleaning device for removing non-magnetic toner remaining on the image carrier after transfer, comprising: And a foreign matter collecting member, which is a conductive cylindrical member rotatably supported in the vicinity of the image carrier on the downstream side of the transfer device, and having magnetic poles capable of adsorbing magnetic carriers on its peripheral surface. , The foreign matter collecting member It is assumed to have a bias power source for collecting agglomerated toner that applies a bias voltage in a direction to attract the toner agglomerates on the image holding member.

According to a second aspect of the present invention, there is provided the first aspect.
In the image forming apparatus according to the item 1,
A bias power supply for toner supply for applying a bias voltage in the direction of transferring the toner on the foreign matter collecting member to the image carrier, a voltage from the bias power supply for collecting aggregated toner, or a voltage from the bias power supply for toner supply And a power source switching means capable of applying the voltage.

The invention according to claim 3 is the above-mentioned claim 1.
Alternatively, in the image forming apparatus according to claim 2, the foreign matter collecting member is provided in the housing of the cleaning device.

In the image forming apparatus according to the first aspect, a flexible blade that is in contact with the foreign matter collecting member and can peel off the magnetic carrier or the toner aggregate adhering to the foreign matter collecting member. It is desirable to have. The foreign matter collecting member may be configured such that, for example, a conductive hollow cylindrical member and a cylindrical magnet that is disposed inside the cylindrical hollow member and has a plurality of magnetic poles along its peripheral surface are the main components. it can. The aggregated toner collecting bias power source can apply a DC voltage on the positive side of the potential of the image portion of the image carrier when, for example, a toner having a negative charging polarity is used. Furthermore, it is desirable that an AC voltage can be applied by superimposing it on this DC voltage.

In the image forming apparatus according to the second aspect, a flexible blade that is brought into contact with the foreign matter collecting member in the step of forming the toner image on the image holding body and separated in the cleaning step of the image holding body is used. It is desirable to have one. Also,
The time for applying the bias voltage in the direction of transferring the toner to the image carrier to the foreign matter collecting member can be appropriately set according to the amount of toner returning to the image carrier.

[0019]

According to the image forming apparatus of the first aspect of the present invention, the foreign matter collecting member supported near the image carrier is set to an appropriate value from the bias power source for collecting aggregated toner ( Since a bias voltage (in the direction of attracting the foreign matter) is applied, when the toner image formed on the image carrier passes through the opposite position to the foreign matter collecting member, the electric field formed at the opposite position causes The toner aggregates adhering to the toner image are transferred to the surface of the foreign matter collecting member. Further, a magnetic pole is provided inside the foreign matter collecting member, and the magnetic carrier attached to the toner image is also attracted to the surface of the foreign matter collecting member by the magnetic attraction force. Therefore, foreign matters such as toner aggregates and magnetic carriers contained in the toner image are removed from the surface of the image carrier without damaging the toner image, and a high quality image without transfer bleeding can be obtained.

In the image forming apparatus according to the second aspect of the present invention, the power source switching means operates in the opposite direction from the bias power source for supplying toner to the foreign matter collecting member (the direction in which toner is transferred to the image carrier). A bias voltage is applied, and by applying such a bias voltage when cleaning the residual toner after transfer, part of the toner peeled off by the cleaning member is re-imaged from the foreign matter collecting member. It is transferred to the body surface. Then, the transferred toner and toner aggregates are removed again from the image carrier by the cleaning member and are collected in the cleaning device. Since such toner and toner aggregates act as a lubricant for the cleaning member during cleaning, it is possible to prevent the occurrence of cleaning failure due to the cleaning member being scraped or the like without increasing the toner consumption amount.

According to the image forming apparatus of the third aspect, since the foreign matter collecting member is provided in the housing of the cleaning device, the toner aggregate and the magnetic carrier removed by the foreign matter collecting member are conveyed. -The collecting means for storing can be used together with the collecting means of the cleaning device. Therefore, new maintenance work associated with the foreign matter collecting member is unnecessary, and the configuration of the device can be simplified and the device can be downsized.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an image forming apparatus which is an embodiment of the invention described in claim 1 or claim 3. This image forming apparatus includes an image carrier 1 on which an electrostatic latent image is formed by irradiating a laser beam from a laser beam generator 3 after being uniformly charged, and an image carrier 1 arranged around the image carrier 1. And four developing devices 4a, 4b, 4c, and 4d respectively containing black, yellow, magenta, and cyan toners.
And the developing device 4 in the rotation direction of the image carrier 1.
A charger 2 that uniformly charges the surface of the image carrier 1 on the upstream side of a, and a toner image on the surface of the image carrier 1 on the paper supplied by the paper guide 8 on the downstream side of the developing device 4d. A transfer charger 5 for transferring, a peeling charger 6 for peeling the transferred sheet from the image carrier 1, a conveyor belt 9 for conveying the peeled sheet, and a downstream side of the peeling charger 6. It has a cleaning device 7 for cleaning the toner remaining on the image carrier 1 and a destaticizing exposure device 10 for destaticizing the image carrier 1.

FIG. 2 is a partially enlarged view showing the cleaning device 7 provided in the image forming apparatus. The cleaning device 7 has a housing 17 having an opening on the side opposite to the image carrier 1 and a cleaning blade 11 that contacts the surface of the image carrier 1 at the time of cleaning and scrapes off the toner not transferred and remaining in the housing. And a foreign matter collecting roller 12 supported in a non-contact manner at a position close to the image holding body 1 on the upstream side of the cleaning blade 11 in the rotation direction of the image holding body 1, and can come into contact with the surface of the foreign matter collecting roller 12. A flexible blade 13 which is supported by the above-mentioned foreign matter collecting roller 12 and peels off the magnetic carrier and the toner aggregate attached to the foreign matter collecting roller 12, and a collecting auger 14 which collects the magnetic carrier and the like peeled off by the flexible blade 13. have.

The cleaning blade 11 is composed of a plate-shaped member made of an elastic material. One end of the cleaning blade 11 is in contact with the surface of the image holding member 1 and can be retracted from the surface of the image holding member by the supporting member 11a near the other end. Supported by. While the toner image is formed on the image carrier 1, the cleaning blade 11 is in a retracted state apart from the image carrier 1, and the transition to the state of contact with the image carrier 1 is the fourth color. This is performed immediately before the leading edge of the image obtained by superimposing the toner images of 1 is reached to the facing position of the cleaning device 7 through the transfer process.

The foreign matter collecting roller 12 is a cylindrical conductive sleeve 12a rotatably supported on the peripheral surface.
And a magnet roll 12b having a plurality of magnetic poles whose positions are fixed inside the sleeve 12a. The foreign matter collecting roller 12 is supported so that the surface of the sleeve 12a maintains a constant distance from the image carrier 1 in a series of steps of the image forming process.
This distance is preferably 0.2 to 0.6 mm, and if it is narrower than this, it tends to affect the toner image, and if it is wider than this, the suction force is weakened. In this embodiment, the distance is set to about 0.3 to 0.5 mm.

The sleeve 12a is rotationally driven at the position facing the image carrier 1 such that the surface thereof is in the same direction as the moving direction of the image carrier. A bias voltage for attracting the toner aggregates is applied from the aggregated toner collecting bias power sources 15 and 16. In this embodiment, the applied bias voltage is V _pp 1 kV under the conditions of a charging potential of the image carrier 1 using an OPC photosensitive member of −650 V, a potential after exposure of −200 V, and a developing bias voltage of −500 V. It is set to a DC voltage of 0 to 50 V on which an AC of about 500 Hz is superimposed. The magnet roll 1
In the magnetic pole arrangement of 2b, the N pole is located at a position facing the image carrier 1.
Two S poles are arranged so as to sandwich the N pole. The magnetic force of this magnet should be as high as possible above 500G,
About 1000 G is preferable.

The image carrier 1 is a cylindrical member having a photoconductor (OPC photoconductor) made of a polymer compound on the surface thereof, which is rotated in a certain direction to uniformly charge the surface and irradiate image light. The electrostatic latent image can be formed by the method.

The developing devices 4a, 4b, 4c and 4d are
It has developing rolls 44a, 44b, 44c and 44d that are rotatably supported and on which a layer of a developer is formed.
These developing rolls and the image carrier 1 are arranged so as to face each other. Further, the developing rolls 44a, 44
A developing bias voltage is applied between b, 44c, 44d and the image carrier 1 at a constant timing from a bias power source (not shown) so that the electrostatic latent image is developed in the bias electric field. Has become. At the time of development, it is devised so that the toner image already formed on the image carrier 1 is not disturbed or a part of the toner forming the toner image is not reversely transferred to the developing device side.

The developer contained in the developing devices 4a, 4b, 4c and 4d is a two-component developer in which a non-magnetic toner and a magnetic carrier are mixed. As the magnetic carrier, a substantially spherical ferrite carrier having an average particle diameter of 50 μm is used, and the surface thereof is coated with a charge control agent for stably charging the toner in a negative polarity. The non-magnetic toner used was one having an average particle size of about 10 μm and a styrene-acrylic resin as a binder and a pigment dispersed therein. This toner is negatively charged by being rubbed with the magnetic carrier in the developing device.

Next, the operation of the image forming apparatus as described above will be described. FIG. 3 is a diagram showing the operation timing of the image forming apparatus. The image carrier 1 is charged by a charger 2, and a latent image corresponding to a black image is formed at a predetermined position on the image carrier 1 by a laser beam 3a from a laser beam generator 3 including a semiconductor laser and a polygon rotating mirror. To be done. At this time, the laser light irradiates the image portion, and the toner having the same polarity charge as the surface potential polarity of the image carrier 1 charged by the charger 2 is discharged from the developing roll 44a in the developing device 4a. The latent image is visualized by transferring to the laser light irradiation portion of the image carrier 1.

At this time, although a small amount, a toner agglomerate having the same polarity (negative polarity) as the toner in the developing device 4a adheres to the image portion on the image carrier 1 and the magnetic force is low and the developing roll 44
A phenomenon occurs in which a carrier having a small adsorptivity with a is transferred onto the image carrier 1. The toner image is conveyed to a position facing the foreign matter collecting roller 12 by the rotation of the image carrier 1 while the toner aggregates and the carrier are attached.

At this opposing position, a bias voltage for adsorbing the toner agglomerates as described above is applied from the bias power sources 15 and 16 for collecting agglomerated toner, and the toner agglomerates charged in the bias electric field are the toner. Transferred from the image carrier 1 onto the foreign matter collecting roller 12 without disturbing the image. Further, a magnet roll 12b having magnetic poles is disposed inside the foreign matter collecting roller 12 at a position facing the image carrier 1, and the carrier, which is a magnetic body, is placed on the foreign matter collecting roller 12 by the attractive force of the magnet. Adsorbed. Therefore, unnecessary toner aggregates and magnetic carriers on the image carrier 1 are removed from the toner image without disturbing the toner image on the image carrier 1,
It is collected in the cleaning device 7. Foreign object collection roller 1
The toner agglomerates and magnetic carriers collected on the surface 2 are peeled off by the flexible blade 13, sent by the transport auger 14 to a not-shown collecting section (remaining toner collecting section at the time of cleaning), and stored in the collecting container. . By sharing the residual toner collecting device in the cleaning device in this manner, new maintenance work associated with the foreign matter collecting means is unnecessary, and the maintenance of the device becomes easy.

The developing device 4a for black has a structure in which it is not in contact with the image carrier 1 at least after the development is completed, and the toner image once developed is not scraped before starting the developing process of another color. It is like this. Also, the cleaning blade 11 in the cleaning device 7 is not in contact with the image carrier 1 during the image forming process.

Next, as the second cycle, the image carrier 1
Is recharged by the charger 2 and is irradiated with the laser beam 3a in the previous (black) step, and the portion of the image carrier 1 whose potential has dropped is restored to the original potential again. After that, the laser light 3a from the laser light generator 3 again irradiates a predetermined position of the image carrier 1 with image light corresponding to yellow to form a latent image. In the yellow developing device 4b, a yellow toner having the same electric charge as the surface potential polarity of the charged image carrier 1 is stored, and the toner is transferred to the laser light irradiation part of the image carrier 1. The latent image is visualized. Unwanted foreign matters such as toner agglomerates and magnetic carriers adhered to the yellow toner image on the image carrier 1 in this developing step are the foreign matter collecting roller 12 like the black toner image of the first color.
Are collected from the image carrier 1.

Similarly, as the third cycle, recharging by the charger 2, irradiation of the magenta image by the laser beam 3a from the laser beam generator 3, development of the magenta image by the magenta developing device 4c, and foreign matter collecting roller are performed. Unwanted foreign matter is removed by 12, and as the fourth cycle, recharging by the charger 2, irradiation of a cyan image by the laser beam 3a from the laser beam generator 3, development of a cyan image by the cyan developing device 4d, Each step of removing unnecessary foreign matter by the foreign matter collecting roller 12 is performed. In this embodiment, 4
In order to collect foreign matters after the development of the cyan image of the color and to prevent the displacement of the image between the colors due to the contact of the cleaning blade 11 with the image carrier 1 during the writing of the image information, As shown in FIG. 3, a dummy cycle of one rotation is provided after the development of the fourth color, and the multicolor image forming cycle is five rotations to make one copy.

When the cyan image developing process by the cyan developing device 4d is completed as described above, a toner image in which four colors of black, yellow, magenta, and cyan are superimposed on the image carrier 1 according to the irradiation image. Exists. The toner image and the image carrier 1 are irradiated with the pre-transfer charger 18 as needed during the dummy cycle and are charged or discharged to a state suitable for transfer, and then the transfer charger 5 guides the paper. The image carrier 1 is placed on the transfer paper that has entered along the line 8.
The toner image in which the above four colors of black, yellow, magenta, and cyan are superimposed is transferred in one step. At this time,
Before transfer, the toner image on the image carrier 1 has the toner agglomerates and carriers that cause transfer unevenness removed by the foreign matter collecting roller 12, so that the transfer sheet is easily attached to the image carrier 1 and the toner image is high. High-quality transfer is possible.

After the transfer step is completed, the transfer sheet is de-charged by the peeling charger 6, separated from the image carrier 1 and conveyed by a conveyor belt 9 to a fixing device (not shown) for the fixing step. Further, in the above-described image forming process, the cleaning blade 11 in the cleaning device 7 is retracted from the image holding member 1. However, the cleaning blade 11 is brought into contact with the image holding member 1 in the cleaning step after the transfer step, and the residual toner is cleaned. Is performed. Then, after the image carrier 1 is rotated, it is continuously exposed to light from the static eliminator exposure device 10, and then the charging process by the charger 2 is started again, and the preceding process is repeated to output a plurality of continuous prints.

In the image forming apparatus as described above, the foreign matter collecting roller 12 is set to 0.3 to the image holding member 1 through the entire process.
Since they are held at an interval of about 0.5 mm, there is an advantage that the scattered toner generated when the cleaning blade 12 is retracted or abutted can be received by the foreign matter collecting roller 12, which can also contribute to the prevention of toner scattering. .

FIG. 4 is a schematic block diagram showing an image forming apparatus which is an embodiment of the invention described in claim 2 or 3. 5 and 6 are explanatory diagrams showing the operation of the image forming apparatus, and FIG. 7 is a diagram showing the timing of the operation. In this image forming apparatus, as in the image forming apparatus shown in FIG.
2 is provided, the difference from the image forming apparatus shown in FIG. 1 is that bias powers 35 and 36 for collecting toner are applied to the foreign matter collecting roller 32 to apply a bias voltage obtained by superimposing an AC voltage on a DC voltage. The DC power source 43 for applying a DC voltage to the foreign matter collecting roller 32 is connected to the power source switching means 40.
It is a point that is switched and connected by.

The bias power supply 35 for collecting the aggregated toner,
From 36, a bias voltage for attracting the toner aggregates on the image carrier 1 (AC component V _pp 1 kV in this embodiment,
500 Hz, DC component 0 to 50 V) is applied. Further, the DC power supply 43 is connected to the AC power supply 42 and the developing rolls 54a, 54b, 54c, 54d in the developing devices 24a, 24b, 24c, 24d, and the switching means 41 is used to connect the developing rolls and the image carrier 1 to each other. And a developing bias voltage between them and a bias voltage (DC component −500V in this embodiment) in a direction in which the toner on the foreign matter collecting roller 32 is transferred to the image carrier 21. It also serves as a power source. The other configuration of the image forming apparatus is the same as that of the image forming apparatus shown in FIG.

In such an image forming apparatus, the image carrier 2
When the toner images are formed on the image forming apparatus 1 by the developing devices 24a, 24b, 24c, and 24d, as illustrated in FIGS. 5 and 7, the foreign matter collecting roller 32 is biased by the aggregated toner collecting bias power sources 35 and 36. A voltage is applied, and the toner agglomerates on the image carrier 21 are collected on the foreign matter collecting roller 32 each time after the development process of each color. Further, the attraction force of the magnet inside the foreign matter collecting roller 32 causes the image carrier 21 to move.
The upper magnetic carrier is also collected. Therefore, in the transfer step, foreign matters that cause transfer unevenness are removed, and a good image without image quality deterioration can be obtained.

Further, after the transfer process, when the residual toner on the image carrier is removed by the cleaning blade 31 of the cleaning device 27, the connection is switched by the power source switching means 40 as shown in FIGS. 6 and 7. The
A bias voltage in the direction of transferring the toner to the image carrier 21 is applied from the DC power source 43 to the foreign matter collecting roller 32. As a result, the toner peeled off by the cleaning blade 31 and dropped on the foreign matter collecting roller 32 is transferred again onto the image holding body 21, and is removed by the cleaning blade 31 again by the rotation of the image holding body 21. Therefore, sufficient toner is supplied to the cleaning blade 31, and the cleaning blade 31 and the image carrier 21
The toner plays a role as a lubricant at the contact portion with. As a result, the cleaning blade 31 is prevented from being scratched at its tip portion or from being damaged by paper dust or the like and damaging the surface of the image holding member, so that the occurrence of defective cleaning can be eliminated.

Further, in the image forming apparatus, the DC power source 43 for applying the bias voltage (DC voltage) to the foreign matter collecting roller 32 is shared with the power source for applying the developing bias voltage at the time of development, and a new power source is added. There is also an advantage that the cleaning failure can be eliminated without doing so. In addition, the above 2
In one embodiment, the case where a multicolor image is formed with four color toners has been described, but even in the single color mode, the dummy cycle for one rotation can be provided to effectively use the foreign matter collecting roller.

[0044]

As described above, according to the first aspect of the invention, foreign matters such as toner aggregates and magnetic carriers mixed in the toner image are transferred without increasing the size of the image forming apparatus. It can be removed from the image carrier in advance, transfer unevenness can be prevented, and an image of good quality can be obtained.
According to the second aspect of the present invention, the cleaning blade can always supply an appropriate amount of toner to the cleaning blade without increasing the toner consumption amount, and the cleaning blade can be used even in the case of continuously making copies with a small image area. It is possible to prevent a cleaning failure due to a scraped portion or the like. Therefore, a high-quality image can be stably supplied. According to the third aspect of the present invention, the transportation and storage of the collected foreign matter can be used together with the cleaning device, the size of the image forming apparatus is not increased, and dedicated maintenance work is not required. Transfer unevenness can be prevented with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus which is an embodiment of the invention described in claim 1 or claim 3.

FIG. 2 is a partial enlarged view showing a cleaning device and an image carrier of the image forming apparatus.

FIG. 3 is a diagram showing a timing of an operation of the image forming apparatus.

FIG. 4 is a schematic configuration diagram showing an image forming apparatus which is an embodiment of the invention described in claim 2 or claim 3;

5 is an explanatory diagram showing an operation of the image forming apparatus shown in FIG.

6 is an explanatory diagram showing an operation of the image forming apparatus shown in FIG.

FIG. 7 is a diagram showing the operation timing of the image forming apparatus shown in FIG.

[Explanation of symbols]

1, 21 Image carrier 2, 22 Charging device 3, 23 Laser light generator 4a, 4b, 4c, 4d, 24a, 24b, 24c, 2
4d Developing device 5, 25 Transfer charging device 6, 26 Peeling charging device 7, 27 Cleaning device 8, 28 Paper guide 9, 29 Conveying belt 10, 30 Eliminating exposure device 11, 31 Cleaning blade 12, 32 Foreign matter collecting roller 13, 33 Flexible Blade 14, 34 Collection Auger 15, 35 Bias Power Source for Collecting Aggregate Toner 16, 36 Bias Power Source for Collecting Aggregate Toner 17, 37 Housing 18, 38 Pre-transfer Charger 19, 39 Support Member 40, 41 Switching Means 42 AC power source 43 DC power source 44a, 44b, 44c, 44d Developing roll 54a, 54b, 54c, 54d Developing roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoyoshi Chihara 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Yoshio Inoue 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. An image carrier capable of carrying a latent image due to a difference in charging potential, an image exposure device for irradiating the image carrier with image light to form a latent image, a magnetic carrier and a non-magnetic toner. A developing device that uses a two-component developer containing a toner to visualize the latent image by attaching non-magnetic toner to the latent image; a transfer device that transfers the toner image on the image carrier to a transfer material; In an image forming apparatus having a cleaning device for removing the non-magnetic toner remaining on the body, on the downstream side of the transfer device in the orbiting direction of the image carrier,
A conductive cylindrical member rotatably supported in the vicinity of the image carrier, the foreign matter collecting member having magnetic poles capable of attracting a magnetic carrier to the peripheral surface; and the foreign matter collecting member, An image forming apparatus comprising: an aggregated toner collecting bias power source for applying a bias voltage in a direction to attract toner aggregates on an image carrier. 2. The image forming apparatus according to claim 1, wherein a bias voltage for supplying toner is applied to the foreign matter collecting member to apply a bias voltage in a direction in which toner on the foreign matter collecting member is transferred to the image carrier. And an electric power source switching unit capable of applying a voltage from the aggregated toner collecting bias power source or a voltage from the toner supplying bias power source. 3. The image forming apparatus according to claim 1, wherein the foreign matter collecting member is provided inside a housing of the cleaning device.