JP2000276025A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an excellent image by efficiently recovering toner remaining on a photoreceptor drum after transferring a visible image on the photoreceptor drum. SOLUTION: The toner incorporates charge control resin and the toner remaining on the photoreceptor drum 18 after transferring the visible image is recovered by a cleaner 39 which recovers the toner when a potential difference is given between the drum 18 and the cleaner 39. Since the toner incorporating the charge control resin is hardly electrified to have a reverse polarity by transfer bias applied to an intermediate transfer drum 21 at the time of transferring, it is excellently recovered by the potential difference given between the drum 18 and a cleaner brush 41.

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 such as a laser printer.

[0002]

2. Description of the Related Art Generally, an image forming apparatus such as a laser printer is provided with a developing roller for carrying toner and a photosensitive drum which is disposed opposite to the developing roller and forms an electrostatic latent image. ing. In the case of a non-contact type electrostatic latent image, the surface of the photosensitive drum is uniformly charged by a charger, and then a laser beam based on predetermined image data is rapidly scanned over the surface by a laser light emitting device. The toner is carried on the developing roller and the toner charged to the same polarity as the photosensitive drum is reversibly developed on the electrostatic latent image to form a visible image on the photosensitive drum. Is formed.

At a position facing the photosensitive drum,
A transfer member to which a predetermined potential difference is applied between the photosensitive drum and the photosensitive drum is provided. That is, for example, when a monochrome image is formed, a transfer roller to which a transfer bias of a reverse polarity is applied to the photosensitive drum is provided as a transfer body, and a monochrome roller formed on the photosensitive drum is provided. The visible image is configured to be transferred to a sheet that enters between the photosensitive drum and the transfer roller by the potential difference while the sheet passes between the photosensitive drum and the transfer roller. When a full-color image is formed,
As a transfer member, an intermediate transfer drum or an intermediate transfer belt to which a transfer bias of a reverse polarity is applied to the photosensitive drum is provided, and on the photosensitive drum, each color such as cyan, magenta, yellow, and black is provided. And a visible image of each color is sequentially transferred to the intermediate transfer drum (or the intermediate transfer belt) by a potential difference between the photosensitive drum and the intermediate transfer drum (or the intermediate transfer belt). By overlapping, a full-color image is formed on the intermediate transfer drum (or the intermediate transfer belt),
This is configured to be collectively transferred to a sheet.

Further, such an image forming apparatus is provided with a residual toner collecting means for collecting the toner remaining on the photosensitive drum after the visible image on the photosensitive drum is transferred. As such a residual toner collecting means, for example, a blade made of urethane rubber is provided so as to rub the surface of the photosensitive drum, and the blade is used to mechanically scrape the residual toner on the photosensitive drum. A conductive brush or roller is provided so as to contact the surface of the photosensitive drum or the surface of the photosensitive drum. There is known a device that electrically collects the same.

[0005]

However, in the case where the residual toner on the photosensitive drum is mechanically scraped off by a blade made of urethane rubber, for example, a toner having good fluidity such as a polymerized toner is used as the toner. When used, it was very difficult to sufficiently scrape it because the fluidity was too good. In particular, there is a problem that when the blade is pressed with a high pressing force to scrape the film, filming occurs on the photosensitive drum and the image is affected.

On the other hand, toner which cannot be scraped off by such a blade may be electrically collected by a brush or a roller. However, the toner which can be collected by this method is applied to a brush or a roller. It must be charged to the opposite polarity to the applied bias. However, before the transfer, the toner is charged in a polarity opposite to that of the transfer body, that is, in a polarity opposite to the bias applied to the brush or the roller, but during the transfer, the toner is charged by the transfer bias applied to the transfer body. It may be injected and charged to a polarity opposite to that before transfer, that is, the same polarity as that of the transfer body, and therefore, it may not be possible to electrically collect it.

[0007] If the toner that cannot be collected remains on the photosensitive drum, a problem arises particularly when a full-color image is formed. That is, when a monochrome image is formed, the uncollected toner remaining on the photosensitive drum is charged again by the charger, and can be collected by the developing roller. However, when a full-color image is formed, For example, with the configuration including the above-described intermediate transfer drum, even if uncollected toner is charged by the charger, the developing roller already carrying toner of a different color faces the photosensitive drum. This causes a problem that toners of different colors are mixed.

In addition, a charge control agent for imparting chargeability is usually blended into the toner. To form such a full-color image, a colorless charge control agent is added to the toner. It is necessary to mix and color with an arbitrary coloring agent. However, for example, a colorless charge control agent such as a quaternary ammonium salt has insufficient chargeability compared to a colored charge control agent such as nigrosine or triphenylmethane. In addition, since the resistance value is low, the rate of charge injection due to the transfer bias applied to the transfer body during transfer is large, and the polarity tends to be opposite to that before transfer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to remove toner remaining on a photosensitive drum after a visible image on the photosensitive drum is transferred. An object of the present invention is to provide an image forming apparatus capable of efficiently collecting and forming a good image.

[0010]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, there is provided a developer carrying member for carrying a developer, a photosensitive member on which an electrostatic latent image is formed, and A transfer member provided with a predetermined potential difference between the photosensitive member and the photosensitive member, wherein the developer carried on the developer carrying member is opposed to an electrostatic latent image formed on the photosensitive member. An image forming apparatus configured to form a visible image on the photoconductor, and to transfer the visible image formed on the photoconductor by opposing the transfer body. After the visible image on the body is transferred, the developer remaining on the photoconductor is provided with a residual developer collection unit that collects the developer by applying a potential difference between the photoconductor and the developer. Is characterized by containing a charge control resin as a charge control agent It is.

By incorporating the charge control resin into the developer, the developer carried on the developer carrier is developed in a well-charged state, and the resistance value can be increased. In some cases, charge is not injected due to the potential difference between the photoconductor and the transfer member, and the polarity is almost the same as that before transfer. Therefore, the developer remaining on the photoreceptor keeps a good charged state before transfer, and is well collected by the potential difference between the photoreceptor and the remaining developer collecting means.

The invention described in claim 2 is the first invention.
Wherein the developer is positively chargeable.

By using a positively charged developer, development can be performed on a positively charged photosensitive member. That is, when using a negatively charged developer,
It is necessary to negatively charge the photoreceptor. For example, if the photoreceptor is negatively charged in a non-contact state using a charger, a large amount of ozone is generated or prevented. For this reason, when charging is performed in a state of contact using a conductive roller or brush, uneven charging may occur on the photoconductor.

On the other hand, when the photoreceptor is positively charged, even if the photoreceptor is charged in a non-contact state using a charger, the generation of ozone is extremely small and the charging can be performed uniformly without charging. . Therefore, by using a positively charged developer, generation of ozone is small and uniform development can be achieved.

[0015] The invention described in claim 3 is based on claim 1.
In the invention described in Item 2, the developer is a polymerized toner obtained by polymerizing a polymerizable monomer.

When the developer is a polymerized toner obtained by polymerizing a polymerizable monomer, the particle size is uniform and close to a true sphere as compared with a pulverized toner, so that the fluidity is extremely good.

The invention described in claim 4 is the first invention.
In the invention according to any one of to 3, the charge control resin is an ionic monomer having an ionic functional group,
It is obtained by copolymerizing the ionic monomer and a copolymerizable monomer.

By making the charge control resin a copolymer of an ionic monomer having an ionic functional group and a monomer copolymerizable with the ionic monomer, By appropriately selecting the ratio, the intermolecular distance between adjacent ionic functional groups can be arbitrarily selected.

The invention described in claim 5 is the same as the invention in claim 4.
Wherein the ionic functional group is a quaternary ammonium salt, and the copolymerizable monomer is a styrene monomer and an acrylic monomer.

If the ionic functional group is a quaternary ammonium salt and the copolymerizable monomer is a styrene monomer or an acrylic monomer, a styrene-acryl copolymer containing a quaternary ammonium salt is used. It is possible to obtain a charge control resin whose main component is coalescence.

The invention described in claim 6 is the third invention.
The invention according to any one of Items 1 to 5, wherein the polymerizable monomer is a styrene monomer and an acrylic monomer.

If the polymerizable monomer is a styrene monomer or an acrylic monomer, a polymerized toner containing a styrene-acryl copolymer as a main component can be obtained.

The invention described in claim 7 is the first invention.
The invention according to any one of the first to sixth aspects, is characterized in that a plurality of the developer carrying members are provided for each different color of the developer.

According to such a configuration, since the charge control agent contained in the developer is a colorless and transparent charge control resin,
A color image can be formed by using a developer containing a colorant of an arbitrary color, providing a plurality of developer carriers for each color, and forming a visible image of each color. .

The invention described in claim 8 is the same as the invention described in claim 7.
In the invention described in the above, for each developer carried on each developer carrier, a visible image is formed on the photoconductor, and a visible image of each color is formed on the transfer body. It is characterized in that a color image is formed by overlapping.

According to such a configuration, a visible image is formed on the photosensitive member for each developer carried on each developer carrier, and the visible image of each color is superimposed on the transfer body. As a result, a color image is formed.

[0027]

FIG. 1 is a side sectional view showing an embodiment of a color laser printer as an image forming apparatus according to the present invention.

In FIG. 1, a color laser printer 1 includes a feeder unit 4 for supplying paper 3 and an image forming unit 5 for forming a predetermined image on the supplied paper 3 in a main body casing 2. And so on.

The feeder unit 4 includes the main body casing 2
A paper feed tray 100 detachably mounted on the bottom of the inside,
A paper pressing plate 6 provided in the paper feed tray 100, a paper feed roller 7 provided above one end of the paper feed tray 100, and a paper feed roller 7 provided downstream of the paper feed roller 7 in the transport direction of the paper 3. And a registration roller 8 to be used.

The sheet pressing plate 6 is capable of stacking the sheets 3 in a stacked manner. The end farther from the paper feed roller 7 is swingably supported, and the end closer to the paper feed roller 7 is vertically movable. , And is urged upward by a spring 9 from the back side. For this reason, as the amount of stacked paper 3 increases, the paper pressing plate 6
Is pivoted downward against the biasing force of the spring 9 with the end farther from the fulcrum as a fulcrum. The uppermost sheet 3 on the sheet pressing plate 6 is pressed from the back side of the sheet pressing plate 6 toward the feed roller 7 by a spring 9, and is fed one by one by the rotation of the feed roller 7. You. Registration roller 8
Is composed of two rollers on the driving side and the driven side, and sends the sheet 3 sent from the sheet feeding roller 7 to the image forming unit 5 after a predetermined registration.

The image forming unit 5 includes a scanner unit 10, a developing unit 11, a fixing unit 12, and the like.

The scanner unit 10 is provided at an upper part in the main body casing 2 and has a laser emitting unit (not shown),
A polygon mirror 13, which is driven to rotate, lenses 14 and 15, reflection mirrors 16 and 17, and the like. A laser beam based on predetermined image data emitted from a laser emitting section is reflected by a polygon mirror as shown by an arrow. 13,
The lens 15, the reflecting mirror 16, the lens 14, and the reflecting mirror 17 are passed or reflected in this order to form a developing unit 11 described later.
The surface of the photosensitive drum 18 is irradiated with high-speed scanning.

The developing unit 11 includes the scanner unit 1
0, a photosensitive drum 18 as a photosensitive member,
The image forming apparatus includes a rotary developing unit 19, a scorotron charger 20, an intermediate transfer drum 21 as a transfer body, a transfer roller 22, and the like.

The rotary developing unit 19 has a cylindrical shape and is rotatably provided on the main body casing 2.
One developing cartridge 24, that is, a cyan developing cartridge 24C, a magenta developing cartridge 24M, a yellow developing cartridge 24Y, and a black developing cartridge 24K are detachably mounted. Each developing cartridge 24 includes a developing roller 25 as a developer carrier, a layer thickness regulating blade 26, and a supply roller 2 respectively.
7 and a toner storage chamber 28. And
The rotary developing unit 19 is provided with each developing cartridge 24.
Is rotatable in the direction of the arrow (clockwise) by the rotational drive of a drive shaft 29 provided at the center so that the developing roller 25 provided at the center can sequentially face the photosensitive drum 18.

The toner storage chamber 28 is filled with a positively chargeable non-magnetic one-component toner having a color of cyan, magenta, yellow and black for each developing cartridge 24. If a positively charged toner is used, development can be performed on the positively charged photosensitive drum 18. That is, when a negatively chargeable toner is used, the photosensitive drum 18 must be negatively charged. For example, the photosensitive drum 18 is negatively charged in a non-contact state using a scorotron type charger 20. In such a case, a large amount of ozone is generated, and in order to prevent the ozone from being generated, if charging is performed in a state where the ozone is contacted using a conductive roller or a brush, uneven charging on the photosensitive drum 18 is caused. May occur. On the other hand, when the photosensitive drum 18 is positively charged, even if the photosensitive drum 18 is charged in a non-contact state using the scorotron-type charger 20, the generation of ozone is extremely small, and the charging can be performed uniformly without charging. it can. Therefore, by using a positively charged toner, generation of ozone is small and uniform development can be achieved.

The toner may be a polymerizable monomer, for example, a styrene monomer such as styrene, or an acrylic resin such as acrylic acid, alkyl (C1 to C4) acrylate, or alkyl (C1 to C4) methacrylate. A polymerized toner obtained by copolymerizing a monomer by a known polymerization method such as suspension polymerization is used.
Such a polymerized toner has a uniform particle diameter and is close to a true sphere as compared with a pulverized toner, and therefore has extremely good fluidity.
Therefore, a good visible image can be formed on the photosensitive drum 18 by being uniformly carried on the developing roller 25, and a high-quality image can be formed.

This toner contains a charge control resin as a charge control agent. More specifically, the charge control resin is made of an ionic monomer having an ionic functional group such as an ammonium salt, for example, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium.P -It is obtained by copolymerizing a toluenesulfonic acid salt and a monomer copolymerizable with such an ionic monomer, for example, a styrene-based monomer or an acrylic-based monomer as described above. . By using such a charge control resin, the distance between the molecules where the ionic functional groups are adjacent to each other can be arbitrarily selected by appropriately selecting the ratio of each monomer. Therefore, when a simple compound having an ionic functional group such as a quaternary ammonium salt is used as the charge control agent, the compounding amount in the toner may be reduced due to the direct adjacency of the ionic functional group. With the increase of the resistance value, the resistance tends to be charged to the opposite polarity at the time of transfer, but if such a charge control resin is used, the density of ionic functional groups adjacent to each other can be reduced, so that As described above, the resistance value does not decrease as the blending amount increases, and the charged state before transfer can be favorably maintained.

In particular, a quaternary ammonium salt-containing styrene-acryl copolymer obtained by copolymerizing the above-mentioned exemplified monomers is excellent in dispersibility and charge stability. A polymerized toner in which a charge control agent containing a styrene-acrylic copolymer containing an ammonium salt as a main component is obtained, is obtained by copolymerizing the above-described exemplified monomers, a styrene-acrylic copolymer. In the case of a polymerized toner having a main component, the polymerized toner and the charge control agent have the same styrene-acrylic composition, and the charge control agent can be more uniformly dispersed in the polymerized toner, and the chargeability and The resistance value can be improved.

Further, since such a charge control resin is colorless and transparent, it can be used as described above for cyan, magenta,
A colorant of each color such as yellow and black can be blended with the toner and used as a colored toner. Note that the toner is further mixed with wax and the like, and an external additive such as silica is added in order to improve fluidity and charging stability. The average particle size of such a polymerized toner is about 6 to 10 μm.

The toner in the toner storage chamber 28 is
The toner is agitated by the agitator 30 rotatably supported and discharged from the toner supply port 31 opened on the side of the toner storage chamber 28.

A supply roller 27 is rotatably disposed at a position lateral to the toner supply port 31. A developing roller 25 is rotatably disposed opposite the supply roller 27. . The supply roller 27 and the developing roller 25 are in contact with each other so that each of them is compressed to some extent.

The supply roller 27 is connected to a metal roller shaft.
A roller made of a conductive foam material is covered. Further, the developing roller 25 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 25 has a coating layer of urethane rubber or silicone rubber containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles or the like. Coated. As described above, by coating the surface of the developing roller 25 with the urethane rubber or silicone rubber coating layer containing negatively chargeable fluorine, the positive chargeability of the toner carried on the surface is improved. Can be. A bias is applied to the developing roller 25 so that a predetermined potential difference is applied between the developing roller 25 and the photosensitive drum 18, and the resistance from the axis to the surface of the developing roller 25 is about 10 ⁴ to about 10 ⁴ .
It is configured to be 10 ⁸ Ω.

In the vicinity of the developing roller 25, a layer thickness regulating blade 26 is provided so as to press on the developing roller 25.

The toner discharged from the toner supply port 31 is supplied to the developing roller 2 by the rotation of the supply roller 27.
5, the supply roller 27 and the developing roller 2
5, and the developing roller 25
The toner supplied above enters between the layer thickness regulating blade 26 and the developing roller 25 with the rotation of the developing roller 25, where it is further triboelectrically charged and becomes a thin layer having a constant thickness. It is carried on the developing roller 25.

On the other hand, the photosensitive drum 18 is provided at a side position of the rotary developing unit 19 so as to be opposed to the developing roller 25 of each developing cartridge 24, and is rotatable in the direction of an arrow (clockwise). This photosensitive drum 18
The drum body is grounded, and its surface is formed of a positively chargeable material such as an organic photoreceptor containing polycarbonate as a main component. Further, the scorotron type charger 20 is disposed above the photosensitive drum 18 at a predetermined interval. This scorotron type charger 20
Is a scorotron-type charger for positive charging that generates corona discharge from a charging wire such as tungsten.
The surface of the photosensitive drum 18 is configured to be uniformly positively charged. Further, the intermediate transfer drum 21
Below the photosensitive drum 18, this photosensitive drum 1
8 and is rotatable in the direction of the arrow (counterclockwise), and a transfer bias is applied so that a predetermined potential difference is applied to the photosensitive drum 18.

After the surface of the photosensitive drum 18 is uniformly positively charged by the scorotron charger 20, the surface of the photosensitive drum 18 is exposed by high-speed scanning of a laser beam from the scanner unit 10, and an electrostatic latent image based on predetermined image data is obtained. An image is formed.

The developing roller 25 of each developing cartridge 24 is opposed to the photosensitive drum 18 by the rotation of the rotary developing unit 19, and in this state, each developing roller 25 is rotated to carry the developing roller 25 on the developing roller 25. Electrostatic latent image formed on the surface of the photosensitive drum 18 when the charged and positively charged toner comes into contact with the photosensitive drum 18, that is, the surface of the uniformly positively charged photosensitive drum 18 Of these, a visible image is formed by selectively transferring to a portion where the potential is lowered by being exposed by a laser beam, whereby development (reversal development) is achieved. Next, the visible image formed on the photosensitive drum 18 is transferred to the intermediate transfer drum 21 facing the photosensitive drum 18.

The rotation of the rotary developing unit 19 causes the developing roller 25 of each developing cartridge 24 to sequentially face the photosensitive drum 18, thereby forming a visible image of each color on the photosensitive drum 18, and A color image is formed by sequentially superimposing the visible images on the intermediate transfer drum 21. That is, for example, when the rotation of the rotary developing unit 19 causes the developing roller 25 of the cyan developing cartridge 24C to face the photosensitive drum 18, a visible image is formed on the photosensitive drum 18 by the cyan toner filled in the cyan developing cartridge 24C. Is formed and transferred to the intermediate transfer drum 21. When the developing roller 25 of the magenta developing cartridge 24M faces the photosensitive drum 18 again by the rotation of the rotary developing unit 19, the magenta developing cartridge 24M is filled with magenta. A visible image is formed on the photosensitive drum 18 by the toner, and the visible image is formed on the intermediate transfer drum 21 on which the cyan toner image has already been transferred. Toner and black developer By repeated by black toner to be filled in cartridge 24K, a full-color image on the intermediate transfer drum 21 is formed.

Below the intermediate transfer drum 21, there is rotatably disposed a transfer roller 22 which is in contact with the intermediate transfer drum 21 in contact therewith. The transfer roller 22 has a metal roller shaft covered with a roller made of a conductive rubber material, and is applied with a transfer bias that gives a predetermined potential difference between the transfer roller 22 and the intermediate transfer drum 21. Therefore, the full-color image formed on the intermediate transfer drum 21 is transferred to the sheet 3 while the sheet 3 passes between the intermediate transfer drum 21 and the transfer roller 22. Transferred paper 3
Is a conveyor belt 3 disposed downstream of the transfer roller 22.
4 transports to the fixing unit 12.

The fixing unit 12 includes the rotary developing unit 1
The heating roller 32 is disposed below the transfer roller 9 and downstream of the transfer roller 22. The pressing roller 33 is pressed by the heating roller 32. The heating roller 32
It is made of metal and has a halogen lamp for heating, and heat-fixes the full-color image transferred onto the paper 3 in the developing unit 11 while the paper 3 passes between the heating roller 31 and the pressing roller 32. Like that. The heat-fixed paper 3 is then transferred to a pair of discharge rollers 35, 3
The paper is sequentially conveyed by 6 and 37 and is discharged onto a discharge tray 38.

In the color laser printer 1 configured as described above, a visible image is formed on the photosensitive drum 18 for each of the toners of cyan, magenta, yellow, and black, and is superimposed on the intermediate transfer drum 21. As a result, a full-color image is formed, which is then collectively transferred to a sheet, whereby a high-quality full-color image is formed on the sheet 3.

In the color laser printer 1 according to the present embodiment, the toner remaining on the photosensitive drum 18 after the visible image on the photosensitive drum 18 is transferred is transferred between the photosensitive drum 18 and the toner. Is provided with a cleaner 39 as a residual developer collecting means for collecting the developer by giving a potential difference to the toner.

The cleaner 39 is provided on the side of the photosensitive drum 18, and includes a cleaner brush 41, a collecting roller 42, a collecting box 43, and a scraping blade 44 in a cleaner casing 40. The cleaner casing 40 is formed integrally with the casing of the scorotron charger 20.

The cleaner brush 41 has a cylindrical body formed with radial brushes, and is rotatable on the side of the photosensitive drum 18 in a state where the brush is in contact with the photosensitive drum 18 in a contact state. It is arranged.
A bias is applied to the cylindrical main body so that a predetermined potential difference is provided between the main body and the photosensitive drum 18.

The recovery roller 42 is made of a metal roller, and is rotatably disposed on the side of the cleaner brush 41 in a state of being in contact with the cleaner brush 41 in a contact state. Further, a bias is applied to the collection roller 42 so that a predetermined potential difference is provided between the collection roller 42 and the cleaner brush 41.

The collection box 43 has an opening on the side of the collection roller 42 facing the collection roller 42, and a scraping blade 44 pressed against the collection roller 42 near the opening. Is provided.

The toner remaining on the photosensitive drum 18 after the transfer of the visible image is transferred to the cleaner brush 41 while being scraped off by the cleaner brush 41 when the photosensitive drum 18 rotates. Attached to the brush by the applied bias. Thereafter, when the residual toner attached to the cleaner brush 41 faces the collection roller 42, the remaining toner adheres to the collection roller 42.
Is applied to the collection roller 42 by the bias applied to the collection box 43, and is then scraped off by the scraping blade 44 and collected in the collection box 43.

In the recovery by the cleaner 39 in this embodiment, since the toner contains a charge control resin having an excellent chargeability and a high resistance value, the toner carried on the developing roller 25 is excellent. The charge is not injected at the time of transfer due to a potential difference between the photosensitive drum 18 and the intermediate transfer drum 21 and almost always has the opposite polarity to that before transfer. Therefore, the toner remaining on the photosensitive drum 18 keeps a good charged state before the transfer, and
Due to the potential difference applied between the photosensitive drum 18 and the cleaner brush 41, the toner can be collected well. Therefore, even if a polymerizable toner having good fluidity that cannot be mechanically scraped off by a blade as in the present embodiment is used, it can be efficiently collected.

In particular, in the color laser printer 1 of the present embodiment, since a visible image is formed on the photosensitive drum 18 every time the color is different, the toner remaining on the photosensitive drum 18 after transfer cannot be efficiently collected. In this case, there is a possibility that toners of different colors may be mixed,
By using such a cleaner 39, the polymerized toner containing the charge control resin can be satisfactorily collected for each color, so that a high-quality full-color image can be formed without causing the image deterioration due to such color mixture. can do.

The cleaner 39 is also provided on the side of the intermediate transfer drum 21 so that the toner remaining on the intermediate transfer drum 21 after being collectively transferred to the sheet 3 can be collected. However, the intermediate transfer drum 21
Can be scraped off with a blade made of urethane rubber. By extremely increasing the pressing force of the blade, the blade can be scraped. Unlike the photosensitive drum 18, if on the intermediate transfer drum 21,
Even if filming occurs, the effect on the image is small.

In the above description of the embodiment,
Although the so-called intermediate transfer type color laser printer has been described, the present invention may be applied to, for example, a tandem type color laser printer or the like, and may be further applied to a laser printer for forming a monochrome image. Good.

FIG. 2 is a sectional side view of a main part of a developing unit of a laser printer for forming such a monochrome image. 2, the developing unit 51 is provided in a laser printer including the above-described feeder unit, scanner unit, fixing unit, and the like.
Photosensitive drum 52 as photosensitive member, developing cartridge 5
3, a scorotron charger 54, a transfer roller 55 as a transfer body, and the like. The developing cartridge 53 is provided with a developing roller 56 as a developer carrier, a layer thickness regulating blade 57, a supply roller 58, a toner storage chamber 66, and the like. Black polymerized toner containing the charged resin.

The polymerized toner is released from the toner supply port 60 opened on the side of the toner storage chamber 66 by stirring of the agitator 65 in the toner storage chamber 66, and is developed by the rotation of the supply roller 58. The developing roller 5 is supplied to the roller 56 and is sufficiently triboelectrically charged by the layer thickness regulating blade 57 and has a constant thickness as a thin layer.
6 is carried.

The photosensitive drum 52 is uniformly and positively charged by a positively-charged scorotron-type charger 54.
Exposure is performed by high-speed scanning of a laser beam from a scanner unit (not shown), and an electrostatic latent image based on predetermined image data is formed. When the toner in contact with and contacts the electrostatic latent image formed on the photosensitive drum 52, it is visualized by being selectively transferred onto the surface of the photosensitive drum 52, thereby forming a reversal image. Is achieved.

The toner developed on the photosensitive drum 52 is transferred to the paper 67 while the paper 67 passes between the photosensitive drum 52 and the transfer roller 55, and is fixed downstream by a fixing unit (not shown). Is done.

In such a developing unit 51, in the embodiment shown in FIG. 2, a cleaner 59 as a residual developer collecting means is provided on a side of the photosensitive drum 52. That is, the cleaner 59 is provided in the cleaner casing 6.
0, a cleaner brush 61, a collecting roller 62, and a scraping blade 63 are provided in the same manner as described above. The toner remaining on the photosensitive drum 52 after the visible image is transferred is rotated by the rotation of the photosensitive drum 52. By cleaner brush 61
When the cleaner brush 61 is scraped off by the cleaner brush 61, the cleaner brush 61 adheres to the brush by a bias applied to the cleaner brush 61.
1 is attached to the collecting roller 62 by a bias applied to the collecting roller 62 when facing the collecting roller 62, and then the scraping blade 63
And is collected in the cleaner casing 60.

In the above configuration, for example, as shown in FIG.
Instead of the scraping blade 63, a sponge roller 64 made of a conductive foam material may be provided as a residual developer collecting means. When the toner is collected by the sponge roller 64, a transfer bias is applied to the sponge roller 64 so that a predetermined potential difference is applied between the sponge roller 64 and the photosensitive drum 52.
After the toner remaining on the toner 2 is attached to the sponge roller 64 and the remaining toner is temporarily stored, a reverse bias is applied at a predetermined timing, and finally the developing roller 5
6 may be used for collection.

In this embodiment, a positively charged toner is used. However, a negatively charged toner may be used, or a pulverized toner may be used instead of the polymerized toner. When a negatively chargeable toner is used, for example, a charge control resin having an anionic functional group may be contained.

[0069]

As described above, according to the first aspect of the present invention, the chargeability and the resistance value of the developer can be improved by including the charge control resin in the developer. Therefore, during transfer, the developer remaining on the photoreceptor does not have a polarity opposite to that before transfer, and can be satisfactorily collected by a potential difference applied between the photoconductor and the remaining developer collection unit. it can. Therefore, for example, polymerized toner having good fluidity, which is difficult to mechanically scrape off with a blade, can be efficiently collected without causing filming on the photoconductor.

According to the second aspect of the present invention, the photosensitive member can be positively charged by using the positively chargeable developer.
Uneven development can be achieved.

According to the third aspect of the invention, since the polymerized toner having extremely good fluidity is used as the developer, the polymerized toner is uniformly carried on the developer carrying member, and the excellent developer is provided on the photosensitive member. A visible image is formed, whereby a high-quality image can be formed.

According to the fourth aspect of the present invention, by appropriately selecting the ratio of each monomer, the distance between adjacent molecules of the ionic functional groups can be arbitrarily selected. Therefore, when a simple compound having an ionic functional group, such as a quaternary ammonium salt, is used as the charge control agent, the compound in the developer is caused by the direct adjacency of the ionic functional group. The resistance value decreases as the amount increases, and it is easy to be charged to the opposite polarity during transfer,
If such a charge control resin is used, the density of the ionic functional groups adjacent to each other can be reduced, so that the resistance value does not decrease as the amount of the ionic functional groups increases, and the ionic functional groups are charged before transfer. And the remaining developer can be collected satisfactorily by the potential difference between the photosensitive member and the residual developer collecting means.

According to the fifth aspect of the present invention, a charge control resin containing a styrene-acrylic copolymer containing a quaternary ammonium salt as a main component can be obtained, so that the dispersibility and the chargeability can be improved. Can be.

According to the sixth aspect of the invention, since the polymerized toner has a styrene-acrylic copolymer as a main component, for example, as in the fifth aspect of the invention, the charge control agent is When a styrene-acrylic copolymer containing a quaternary ammonium salt is used as the main component, the polymerized toner and the charge control agent have the same styrene-acrylic composition, so that the polymerized toner is more uniformly charged. The control agent can be dispersed, and the chargeability and the resistance value can be further improved.

According to the seventh aspect of the present invention, since the charge control agent contained in the developer is a colorless and transparent charge control resin, a developer containing an arbitrary colorant is used. Accordingly, a color image can be formed by providing a plurality of developer carriers for each different color of the developer and forming a visible image of each color.

According to the eighth aspect of the invention, a color image is formed by superimposing the visible image on the photosensitive member formed for each developer on the transfer member.
For example, a high-quality full-color image can be formed on a recording medium by batch-transferring to a recording medium such as paper. Further, in such a configuration, since a visible image is formed on the photoreceptor each time the color is different, if the developer remaining on the photoreceptor after transfer cannot be efficiently collected, the colors differ from each other. Although there is a possibility that the developer may be mixed, in the present invention, since the developer for each color can be satisfactorily collected by the remaining developer collecting means as described above, an image caused by such a mixed color can be obtained. It is possible to form a high-quality full-color image without lowering the image quality.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of an embodiment of a color laser printer as an image forming apparatus of the present invention.

FIG. 2 is a side sectional view of a main part of a developing unit of a laser printer for forming a monochrome image.

FIG. 3 is a side sectional view of a main part showing a mode in which a sponge roller is used in place of the cleaner brush and the collection roller in the developing unit shown in FIG. 2;

[Explanation of symbols]

 1 Color Laser Printer 18 Photosensitive Drum 21 Intermediate Transfer Drum 25 Developing Roller 39 Cleaner 52 Photosensitive Drum 55 Transfer Roller 56 Developing Roller 59 Cleaner

Claims (8)

[Claims] An image forming apparatus comprising: a developer carrier for carrying a developer; a photoconductor on which an electrostatic latent image is formed; and a transfer body having a predetermined potential difference between the photoconductor and the developer. A visible image was formed on the photoconductor by the developer carried on the carrier facing the electrostatic latent image formed on the photoconductor, and the developer was formed on the photoconductor. In an image forming apparatus configured to transfer a visible image by opposing the transfer member, the development remaining on the photoconductor after the visible image on the photoconductor is transferred A residual developer collecting means for collecting the developer by giving a potential difference between the photosensitive member and the photosensitive member, wherein the developer contains a charge control resin as a charge control agent. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the developer is positively chargeable. 3. The image forming apparatus according to claim 1, wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer. 4. The charge control resin is obtained by copolymerizing an ionic monomer having an ionic functional group with a monomer copolymerizable with the ionic monomer. The image forming apparatus according to claim 1, wherein: 5. The method according to claim 1, wherein the ionic functional group is a quaternary ammonium salt, and the copolymerizable monomers are a styrene monomer and an acrylic monomer.
The image forming apparatus according to claim 4. 6. The image forming apparatus according to claim 3, wherein said polymerizable monomer is a styrene monomer and an acrylic monomer. 7. The image forming apparatus according to claim 1, wherein a plurality of developer carriers are provided for each of different colors of the developer.
An image forming apparatus according to any one of claims 1 to 6. 8. A visible image is formed on the photoconductor for each of the developers carried on each of the developer carriers, and the visible image of each color is superimposed on the transfer body. The image forming apparatus according to claim 7, wherein the image forming apparatus is configured to form a color image by moving.