JP2005315962A - Image forming apparatus and image forming method using the image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which, in image formation by a two-component developer system where a latent image is developed with a spherical small-diameter toner, spherical small-diameter toner remaining on a surface of an image carrier is well cleaned and a good image is obtained, and to provide an image forming method using the image forming apparatus. <P>SOLUTION: The image forming apparatus comprises at least a developing device by a two-component developer system for developing a latent image on an image carrier with a spherical small-diameter toner; a transfer device for transferring the developed clear image onto a transfer material; a blade cleaning device having an electrically conductive cleaning blade for removing residual spherical small-diameter toner after transfer; and an amorphous particle feed unit for feeding charged amorphous particles. A voltage whose polarity is reverse to that of the amorphous particles is applied to the electrically conductive cleaning blade to deposit the amorphous particles on a cleaning blade edge, whereby the residual spherical small-diameter toner is stemmed and removed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to a two-component developer type image forming technique for developing with a spherical small-diameter toner. The present invention relates to an image forming apparatus that removes spherical small-diameter toner remaining on the surface of an image carrier by holding and obtains good cleaning properties and good image characteristics, and an image forming method using the image forming apparatus. is there.

In recent years, an image forming apparatus using an electrophotographic method has been improved in image quality, and one of the countermeasures is to reduce the diameter of the toner and to make it spherical. That is, by reducing the diameter of the toner, an image that is faithful to the latent image formed on the image carrier (photoreceptor) is obtained by exposure, and the developability and transferability are improved by making it spherical. The idea is to improve image quality.
When a pulverization method, which is a conventional typical toner production method, is used to reduce the toner diameter, the yield is poor and the cost is increased. Due to such circumstances, recently, a toner using a polymerization method that is advantageous in terms of cost even when the diameter is reduced or spheroidized has been manufactured. For example, a suspension polymerization method, an emulsion polymerization method, or a dispersion polymerization method can be used. A spherical small-diameter toner manufactured by applying a method or the like has been obtained.

However, when developing with a toner having a reduced diameter and a spherical shape, there is a drawback that it is difficult to clean the spherical small diameter toner remaining on the photoreceptor. For example, even with a blade cleaning method in which a widely used rubber blade is pressed against a photoreceptor to remove residual toner, there is a phenomenon that toner slips between the blade and the photoreceptor.
The cause of this slip-through phenomenon is that when the particle size distribution is spherical and narrow, the toner trapped by the blade edge is likely to be packed most closely, and the trapped toner layer behaves like a single aggregate. The force that pushes up the blade works and the idea that slip-through occurs, or in the case of small-diameter toner, the spherical toner easily enters while rolling into the minutely deformed gap of the blade edge, causing slip-through There is a way of thinking.

For this reason, as a means for solving the above-mentioned problems, blade-shaped spherical toner is cleaned by depositing irregular shaped particles that are unlikely to be compacted or rolled on the blade edge and forming a damming layer with the deposited irregular shaped particles. Have been proposed (see, for example, Patent Document 1 and Patent Document 2).
However, the irregular particle weir layer in the above method is merely deposited on the blade edge, and the irregular particles are repelled by the vibration of the blade. As a result, there is a problem that good cleaning properties cannot be obtained.

Therefore, in order to firmly hold the deposited layer of irregular shaped particles, a method has been proposed in which the irregular shaped particles contain magnetic powder, the blade is provided with a magnetic field generator, and the irregular shaped particles are deposited and held by the magnetic force on the blade edge. (For example, refer to Patent Document 3).
However, by providing a magnetic field generator on the blade, magnetic materials other than the irregular particles are deposited and held on the blade edge, and various problems occur. For example, in a method of developing a latent image using a two-component developer (hereinafter referred to as a two-component development method), a magnetic material is used as a carrier, so that a carrier to be removed attached to the photosensitive member is also deposited. This will cause a problem of scratching the photoreceptor and causing an abnormal image. From this point of view, it is difficult to use a method of depositing and holding amorphous particles on the blade edge by magnetic force in the two-component developer system. Particularly recently, a small-diameter carrier capable of forming a dense magnetic brush has been used to improve image quality. However, when the carrier particle size is reduced, carrier adhesion is likely to occur on the photosensitive member, and the method of depositing and holding irregularly shaped particles on the blade edge by magnetic force causes a particularly serious problem.
In addition to the above problems, there are other problems such as that the applicable toner is limited to only non-magnetic, or that the cleaning device is enlarged by providing a magnetic field generator on the blade.

JP-A-8-254873 JP 2001-166659 A JP 2002-6710 A

  The present invention has been made in view of the above prior art, and deposits and holds amorphous particles stably on a blade edge in two-component developer type image formation in which a latent image is developed with a spherical small-diameter toner. Provides an image forming apparatus that removes spherical small-diameter toner remaining on the surface of the image carrier (photosensitive body) and obtains good cleaning properties and good image characteristics, and an image forming method using the image forming apparatus. The purpose is to do.

As a result of intensive studies, the present inventors have supplied charged amorphous particles from an amorphous particle supply device in image formation of a two-component developer system that develops with a spherical small-diameter toner, and the amorphous particles are supplied with a conductive cleaning blade. It remains on the surface of the image carrier (photoreceptor) by depositing on the edge and applying a voltage of the opposite polarity to the charging characteristics of the irregular particles to the conductive cleaning blade to firmly hold the irregular particles on the blade edge. The present inventors have found that the spherical small-diameter toner is removed to obtain good cleaning characteristics and high-quality image characteristics, and that the above-mentioned problems can be solved, leading to the present invention.
That is, the present invention relates to an image forming apparatus and an image forming method according to claims 1 to 9 described below, thereby solving the problems. Hereinafter, the present invention will be specifically described.

According to the first aspect of the present invention, a developing device of a two-component developer system that develops at least a latent image formed on an image carrier with a spherical small-diameter toner, and a developed image on the developed image carrier is transferred to a transfer material. An image forming apparatus comprising: a transfer device configured to transfer a blade cleaning device having a cleaning blade that removes spherical small-diameter toner remaining on the surface of the image carrier after transfer;
The image forming apparatus includes an amorphous particle supply device that supplies charged amorphous particles that are deposited on the edge of the cleaning blade to dampen the residual spherical small-diameter toner,
The cleaning blade is an image forming apparatus in which a voltage is applied so as to be electrically conductive and to be charged with a polarity opposite to that of the amorphous particles.

  A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the charged amorphous particles are charged with a polarity opposite to that of the spherical small-diameter toner for developing the latent image.

According to a third aspect of the present invention, the ratio (D _f / D _t ) of the volume average particle diameter D _{f of the} irregularly shaped particles and the volume average particle diameter D _t of the spherical small diameter toner for developing the latent image is 2.4> (D The image forming apparatus according to claim 1, wherein a relationship of _f / D _t ) is satisfied.

In a fourth aspect of the invention, the ratio (D _f / D _t ) of the volume average particle diameter D _{f of the} irregularly shaped particles to the volume average particle diameter D _t of the spherical small diameter toner for developing the latent image is 1.2> (D The image forming apparatus according to claim 1, wherein a relationship of _f / D _t ) is satisfied.

  According to a fifth aspect of the present invention, in the spherical small-diameter toner for developing the latent image, the volume average particle diameter is 9 μm or less, and the circularity is 0.92 or more. This is an image forming apparatus.

  The invention of claim 6 is characterized in that the spherical small-diameter toner for developing the latent image has a volume average particle diameter of 5.5 μm or less and a circularity of 0.98 or more. The image forming apparatus described in the above.

  A seventh aspect of the present invention is the image forming apparatus according to the first aspect, wherein the weight average particle diameter of the carrier of the developer used in the two-component developer system is 50 μm or less.

  The invention according to claim 8 is the image forming apparatus according to claim 1, wherein the weight average particle diameter of the carrier of the developer used in the two-component developer method is 30 μm or less.

According to a ninth aspect of the present invention, there is provided a developing device of a two-component developer system that develops at least a latent image formed on an image carrier with a spherical small-diameter toner, and a developed image on the developed image carrier is transferred to a transfer material. Forming a transfer device, a blade cleaning device having a cleaning blade for removing the spherical small-diameter toner remaining on the surface of the image carrier after the transfer, and an amorphous particle supply device for damming the residual spherical small-diameter toner An image forming method using an apparatus,
Pressing the cleaning blade against the surface of the image carrier, depositing charged irregularly shaped particles on the edge of the cleaning blade to dampen the residual spherical small diameter toner,
An image forming method is characterized in that an image is formed by applying a voltage so that the cleaning blade is conductive and is charged with a polarity opposite to that of the amorphous particles.

The image forming apparatus of the present invention is provided with an irregular particle supply device for supplying irregular particles, and the cleaning blade of the blade cleaning device is made conductive, and a voltage is applied so as to have a polarity opposite to the charging characteristics of the irregular particles. With this configuration, the charged irregularly shaped particles are electrostatically adsorbed and deposited on the cleaning blade edge having the opposite polarity, so that a strong irregular particle damming layer is formed on the blade edge portion. For this reason, the spherical small-diameter toner does not enter from the clean blade edge, and the residual spherical small-diameter toner can be cleaned extremely well, and good image characteristics can be obtained.
In particular, if the ratio of the volume average particle diameter D _f and spherical diameter toner having a volume average particle diameter D _t of the irregular particles (D _f / D _t) is to satisfy the relation of _{2.4> (D f / D t} ), More preferably, when the relationship 1.2> (D _f / D _t ) is satisfied, the spherical small-diameter toner can be suitably prevented from entering.
In addition, when the volume average particle diameter of the spherical small diameter toner is 9 μm or less and the circularity is 0.92 or more, the volume average particle diameter is more preferably 5.5 μm or less and the circularity is 0.98 or more. In this case, good developability and transferability, and high-definition image quality can be obtained.
In addition, since no means such as a magnetic field is used, there is a problem that when a two-component developer is used, the carrier, which is a magnetic particle, is adsorbed and held on the blade edge to damage the photoconductor and cause an abnormal image. Does not occur. Furthermore, there is no problem that the applicable toner is limited to non-magnetic only, or the cleaning device is enlarged.

  As described above, the image forming apparatus of the present invention is developed with the two-component developer type developing means (developing device) that develops the latent image formed on the image carrier (photosensitive member) with the spherical small-diameter toner. A transfer means (transfer device) for transferring a visible image on the image carrier to a transfer material; a blade cleaning means (blade cleaning device) having a cleaning blade for removing spherical small-diameter toner remaining on the surface of the image carrier after transfer; Furthermore, in order to dam the residual spherical small diameter toner, an irregular particle supply means (amorphous particle supply device) for supplying charged irregular particles to be deposited on the cleaning blade edge pressed against the surface of the image carrier is provided. The cleaning blade is conductive and is applied with a voltage so as to be charged with a polarity opposite to that of the irregular shaped particles. Hereinafter, the charged indefinite particle supply device, the indeterminate shape particle, the conductive cleaning blade, and the two-component developer (spherical small-diameter toner and carrier), which are features of the present invention, will be described.

[Supplying device for charged amorphous particles]
As described above, the image forming apparatus according to the present invention is provided with an amorphous particle supply device that supplies charged amorphous particles. The amorphous particle supply device is configured such that charged amorphous particles are electrically conductive. Any device can be used as long as it is deposited by a cleaning blade edge (abbreviated as blade edge), and there is no particular limitation. For example, as the irregular particle supply device, a device similar to the case of a dedicated developing device (one-component developing device) in which a commonly used latent image developing toner (irregular particle) is stored can be applied. .
As a result, the charged amorphous particles developed and supplied to the image carrier are accumulated at the blade edge to form a damming layer, and the spherical small-diameter toner remaining on the surface of the image carrier can be removed.
In the case of an image forming apparatus equipped with an intermediate transfer member, the irregularly shaped particles are developed and supplied by the intermediate transfer member, that is, the amorphous particles charged via the intermediate transfer member are supplied to the image carrier (photosensitive member). A method of depositing on the blade edge may be applied.
A specific example of the amorphous particle supply device will be described later.

[Irregular particles]
In the present invention, the irregularly shaped particles supplied from the irregularly shaped particle supply device can be charged to a predetermined polarity and accumulate on the blade edge pressed against the surface of the image carrier. There is no particular limitation as long as the spherical small diameter toner can be prevented from entering or consolidating from the portion. For example, toner particles produced by a normal pulverization method having protrusions and ridge corners may be used.
The polarity of the amorphous particles can be controlled to be charged to a predetermined polarity by a charging member provided in an amorphous particle supply device (for example, a one-component developing device).

Regarding the volume average particle diameter D _f of the irregular shaped particles, the ratio (D _f / D _t ) to the volume average particle diameter D _{t of} the spherical small diameter toner for developing the latent image is preferably less than 2.4. More preferably, it is smaller than .2.
When D _f / D _t is large (2.4 or more), the gap between the irregular shaped particles deposited on the blade edge becomes large and the spherical small-diameter toner tends to enter, and the cleaning property tends to deteriorate. In addition, the said volume average particle diameter is measured by the method described below.

The charged polarity of the charged amorphous particles in the present invention is more preferably the opposite polarity to the spherical small-diameter toner for developing the latent image.
That is, since a voltage is applied to the conductive cleaning blade so that it is charged with a polarity opposite to that of the amorphous particles, if the polarity of the amorphous particles is opposite to that of the spherical small-diameter toner, the cleaning blade and the spherical small-diameter Toner becomes the same polarity. As a result, the spherical small diameter toner repels against the cleaning blade, making it difficult for the toner to enter from the blade edge.

[Conductive cleaning blade]
As described above, the blade cleaning device provided in the image forming apparatus of the present invention has a cleaning blade for removing spherical small-diameter toner, and a voltage is applied so as to be charged with a polarity opposite to that of the amorphous particles. Therefore, it is configured to maintain conductivity. For example, examples of the conductive cleaning blade used in the present invention include a conductive rubber blade (conductive blade).
As such a conductive blade, for example, a carbon black or a conductive material such as an ionic conductive material dispersed when kneading urethane rubber may be used, or a urethane rubber blade may be used. After forming into a shape, you may use what was comprised by coating the surface with the electroconductive material.
The conductive blade is attached to the metal holder, and the conductive blade and the metal holder are configured to be electrically connected. In this case, the conductive blade and the metal holder may be crimped to ensure continuity, may be bonded using a conductive adhesive, or may be conductive using a conductive tape or conductive paint. It may be secured. The metal holder is connected to a DC power source and is controlled so that a voltage having a polarity opposite to that of the amorphous particles is applied.

[Spherical small diameter toner]
In the present invention, the toner that is supplied from a two-component developer type developing device and develops a latent image is a spherical small-diameter toner as described above.
Specifically, the circularity of the toner particles is 0.92 or more, and the volume average particle diameter is 9 μm or less. When the circularity is smaller than 0.92, the developability and transferability are not good, and when the volume average particle diameter is larger than 9 μm, a high-definition image cannot be obtained. The volume average particle size is more preferably 5.5 μm or less. By setting the volume average particle size to a particle size of 5.5 μm or less, an image with higher definition and higher image quality can be obtained. On the other hand, the circularity is more preferably 0.98 or more. By setting the circularity to 0.98 or more, developability and transferability are improved, and a higher quality image can be obtained.
(Roundness)
As a method for measuring the circularity of the toner, an optical detection band method is suitable in which a suspension containing particles is passed through an imaging unit detection band on a flat plate, and a particle image is optically detected and analyzed by a CCD camera. It is. The circularity is calculated by a value obtained by dividing the circumference of the equivalent circle having the same projected area obtained by this method by the circumference of the actual particle.
This value can be measured as an average circularity by a flow type particle image analyzer FPIA-2100 (manufactured by Toa Medical Electronics Co., Ltd.). As a specific measurement method, a surfactant, preferably an alkylbenzene sulfonate, is added to 0.1 to 0.5 ml as a dispersant in 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes.
(Volume average particle size)
The average particle size and particle size distribution of the toner can be measured by various methods such as Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter). In the present invention, Coulter Counter TA-II (manufactured by Coulter) Was used. An interface for outputting number distribution and volume distribution (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) are connected, and 1% NaCl aqueous solution is prepared using first grade sodium chloride as the electrolyte. In addition, ISOTON-II (manufactured by Coulter Science Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably 1% alkylbenzenesulfonate is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. The toner having a volume average diameter of 4.01 to 9.0 μm is used as the aperture by the Coulter counter TA-II type, and the 100 μm aperture is used. For the toner having a volume average diameter of 4 μm or less, the volume distribution and the number distribution were calculated by measuring the volume and number of the toner using a 50 μm aperture. Then, the volume-based volume average particle diameter obtained from the volume distribution according to the present invention was calculated.

As an example of the spherical small diameter toner in the present invention, for example, a toner material solution containing at least a resin material for a binder or / and a prepolymer thereof, a colorant, and a release agent in an organic solvent is finely dispersed in an aqueous medium. After being dispersed in the form of droplets, the product obtained by removing the organic solvent and the aqueous medium, or during or after the toner material solution is formed into fine droplets in the aqueous medium, A product obtained by crosslinking and / or elongation reaction of the prepolymer in the droplets and then removing the organic solvent and the aqueous medium is used.
Preferably, a compound having active hydrogen and a polymer having a site capable of reacting with this active hydrogen or / or a self-polymerizable material having simultaneously active hydrogen and a site capable of reacting with this active hydrogen in the molecule, and a colorant And a release agent as a composition dissolved or dispersed in an organic solvent, and after reacting a site capable of reacting with the active hydrogen, or while reacting, the organic solvent and the aqueous medium are removed, followed by washing. Can be manufactured by drying.
The circularity of the toner may be adjusted by adjusting the stirring strength during the reaction or by stirring strongly after drying.
Various materials can be used as the resin material or / and the prepolymer, and in particular, a polyester resin and a polyester prepolymer can be preferably used.
These are merely examples, and the spherical small-diameter toner may be manufactured by a method other than such a manufacturing method.

[Career]
The carrier mixed with the so-called spherical small-diameter toner of the two-component developer filled in the two-component developer type developing device of the present invention preferably has a weight average particle size of 50 μm or less, more preferably 30 μm or less.
When the weight average particle size is 50 μm or less, the image quality is improved, and when it is 30 μm or less, the image quality is further improved. Thus, by reducing the diameter of the carrier, a dense magnetic brush is formed, development that is faithful to the latent image is possible, and high image quality is expected.
In the present invention, the weight average particle size referred to for the carrier is Dw calculated based on the particle size distribution (relationship between the number frequency and the particle size) of the particles measured on a number basis.
The weight average particle diameter Dw in this case is represented by the following formula (1).
DW = {1 / Σ (nD3)} × {Σ (nD4)} (1)
In the formula (1), D represents a representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel.
The channel indicates a length for equally dividing the particle size range in the particle size distribution diagram. In the present invention, a length of 2 μm is adopted.
Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size stored in each channel was adopted.
As a particle size analyzer for measuring the particle size distribution in the present invention, a Microtrac particle size analyzer (model HRA9320- × 100: manufactured by Honeywell) was used.
The conditions are as follows.
Particle size range: 100-8 μm
Channel length (channel width): 2 μm
Number of channels: 46

The carrier core material (core material) constituting the carrier is not particularly limited, but conventionally known magnetic particles can be used.
Examples of the magnetic particles include magnetite, hematite, Li-based ferrite, Cu—Zn-based ferrite, Mn—Zn-based ferrite, Ni—Zn-based ferrite, Ba ferrite, iron, cobalt, nickel, and the like. When these are used as the core material, various particles such as single crystal / or amorphous particles, single / or composite sintered bodies, or single / or composite particles are dispersed in a polymer material such as a resin. Can be used in any form of core material.

Moreover, it does not restrict | limit especially as a material composition component of the carrier coat layer which comprises a carrier, A conventionally well-known material can be used.
Examples of the material composition of the carrier coat layer used include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polystyrene, acrylic resin (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, Polyvinyl and polyvinylidene resins such as polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymers; silicone resins composed of organosiloxane bonds or modified products thereof (for example, Modified products with alkyd resin, polyester resin, epoxy resin, polyurethane resin, etc.); Perhydropolysilazane or modified products thereof (partially oxidized products) Fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; urea resins; melamine resins; benzoguanamine resins; It is done. Among them, as a preferable coating layer material for satisfying the constituent requirements of the present invention, a silicone resin or a modified product thereof, a fluorine resin, particularly a silicone resin or a modified product thereof is more preferable.

Next, an image forming apparatus of the present invention and an image forming method using the same will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention. The image forming apparatus of the present invention is not limited to the image forming apparatus shown in FIG.
In FIG. 1, an image carrier 8 is an organic photoreceptor showing negative charging characteristics. In addition, as the irregular particle supply device 6 which is a feature of the present invention, for example, a one-component developing device filled with pulverized toner as irregular particles can be provided. FIG. 2 shows an enlarged configuration diagram of a main part of the amorphous particle supply device 6.
As shown in FIG. 2, the irregular particle supply device 6 supplies the developing roller 21 for developing and supplying the pulverized toner 27, which is an irregular particle, to the image carrier 8 (FIG. 1), and the pulverized toner. A replenishing roller 22, a pulverized toner conveying material 23 that conveys the pulverized toner toward the replenishing roller 22, a pulverized toner regulating roller 24 that thins the pulverized toner supplied onto the developing roller 21, and a case 25 for attaching them. The pulverized toner regulating roller 24 and a metal spring 26 for urging them toward the developing roller 21 are provided.

  The pulverized toner 27 is supplied to the surface of the developing roller 21 via the toner conveying member 23 and the supply roller 22. The pulverized toner 27 supplied onto the developing roller 21 is further thinned to a predetermined amount by the contact pressure of the toner regulating roller 24. By rotating the developing roller 21, the image carrier 8 (photosensitive member) in FIG. It is conveyed to. The developing roller 21 is in contact with the photosensitive member in parallel, and a bias that is substantially intermediate between the charged potential of the photosensitive member and the residual potential after optical writing is applied. The pulverized toner 27 on the developing roller 21 is brought into contact with the photosensitive member, and the pulverized toner is supplied to the photosensitive member with a developing electric field generated by the photosensitive member potential and the developing bias.

When the pulverized toner 27 has a negative charging polarity, the photosensitive member is irradiated with laser light, and the irregular particles are supplied to the photosensitive member. When the pulverized toner 27 has a positive charging polarity, the laser beam is written. It can be supplied to the charged potential portion without carrying out the dusting.
In addition, the irregular particle supply device has a contact / separation mechanism with the image carrier 8 (photosensitive member), and supplies irregular particles by contacting the photosensitive member only when supplying irregular particles. It is not in contact with the photoconductor. The supply of the irregular shaped particles is controlled by a controller and can be supplied at a desired timing.

In FIG. 1, the irregularly shaped particles supplied from the irregularly shaped particle supply device 6 to the image carrier 8 that is a photosensitive member are moved to the conductive cleaning blade edge of the blade cleaning device 7 downstream by the rotation of the image carrier 8. Is deposited. An enlarged schematic view of the cleaning blade portion of the blade cleaning device 7 is shown in FIG.
In FIG. 3, 31 is a conductive cleaning blade in which carbon black is dispersed in urethane rubber. This cleaning blade is attached to the metal support 33 with the conductive adhesive 34, and electrical connection with the metal support is ensured. Further, a DC power source is connected to the metal support 33 as shown in FIG. 1, and a voltage having a charging polarity opposite to that of the amorphous particles is applied. In the case of the irregular shaped particles, since it has a negative charging polarity, a positive voltage (for example, 100 V) is applied. The irregularly shaped particles 35 dammed by the conductive cleaning blade 31 that is in contact with and pressed against the image carrier 8 are electrostatically attracted and held on the edge of the cleaning blade 31 as a solid deposited layer of irregularly shaped particles. Is done.

In the image forming apparatus of FIG. 1 configured as described above, first, after the image carrier 8 is uniformly charged by the charging device 1, a laser beam is irradiated from the exposure device 2 to write a latent image. As a result, an electrostatic latent image is formed on the surface of the image carrier 8. Next, the electrostatic latent image is developed into a toner image with a spherical small-diameter toner supplied from the two-component developer type developing device 3. The developed toner image (developed image) is transferred to a transfer material 8 such as transfer paper by the transfer roller 4, and then the toner image is fixed to the transfer material 8 by the fixing device 5.
The residual toner remaining on the surface of the image carrier 8 is cleaned by the blade cleaning device 7 in which the irregularly shaped particles are firmly held on the edge of the conductive cleaning blade 31.

  The image forming method of the present invention uses the apparatus configured as shown in FIG. 1 to press the cleaning blade against the surface of the image carrier and deposit charged amorphous particles on the edge of the cleaning blade to reduce the residual spherical small diameter. In addition to blocking the toner, the cleaning blade is made conductive, and an image is formed by applying a voltage so as to be charged with a polarity opposite to that of the amorphous particles.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof.
Example 1
Using the image forming apparatus having the schematic configuration illustrated in FIG. 1, the cleaning properties and image characteristics were evaluated under the following conditions.
The developer prepared as follows was used as the developer in which the spherical small-diameter toner and the carrier mixed in the developing device 3 of the two-component developer type in FIG. 1 were mixed.
Toner: A spherical small diameter toner having an average circularity of 0.95 and volume average particle size of 6.5 μm prepared by a polymerization method was used.
Carrier: A carrier having a weight average particle diameter of 55 μm, which is a silicone-coated Cu—Zn ferrite core material, was used.
Two-component developer: A spherical small-diameter toner and a carrier were mixed at a ratio of 7:93 (parts by weight) to obtain a two-component developer, which was used by being filled.
The toner was negatively charged.
Further, as the irregularly shaped particles filled in the irregularly shaped particle supply device 6, a pulverized toner having a volume average particle diameter of 14 μm was used. The irregular particles showed a negative charging polarity on the developing roller 21 of the irregular particle supply device 6.
A voltage of +100 V was applied to the conductive cleaning blade 7 ′ so that the irregularly shaped particles were deposited and adsorbed on the edge of the cleaning blade.

[Evaluation]
After supplying the above-mentioned irregular shaped particles from the irregular shaped particle supply device 6 to the cleaning blade edge, the running of printing the image of the S-5 chart was performed. The number of printed sheets was 150,000 (150K), and the cleaning property and the image quality were evaluated according to the following evaluation criteria at the initial stage, 5K sheet, 50K sheet and 150K sheet.
Evaluation of cleanliness:
The rank of the cleaning property was evaluated and evaluated in five stages. 5 is the best and 1 is poor. The allowable level that can withstand actual use is 3 or more.
Image quality rating:
As image quality evaluation, half-tone unevenness, resolving power, sharpness, etc. were comprehensively evaluated, and a 5-level rank evaluation was performed. 5 is the best and 1 is bad. The allowable level that can withstand actual use is 3 or more.
The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 2
In Example 1, the charging polarity of the amorphous particles was changed from negative to positive, and the voltage applied to the cleaning blade was changed from +100 V to −100 V, and the evaluation of cleaning properties and image quality was the same as in Example 1. Went. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 3
In Example 2, the cleaning property and the image quality were evaluated in exactly the same manner as in Example 2 except that the amorphous particles were used by changing the volume average particle size from 14 μm to 12 μm. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 4
In Example 3, the cleaning property and the image quality were evaluated in exactly the same manner as in Example 3 except that the volume-average particle size of the irregular shaped particles was changed from 12 μm to 7 μm. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 5
In Example 4, the volume average particle size of the toner used was changed from 6.5 μm to 5.4 μm, and the volume average particle size of the amorphous particles was changed from 7 μm to 6.2 μm. The cleaning property and image quality were evaluated in exactly the same manner as in Example 4. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 6
In Example 5, the cleaning property and the image quality were evaluated in exactly the same manner as in Example 5 except that the circularity of the toner was changed from 0.95 to 0.98. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 7
In Example 6, the cleaning property and the image quality were evaluated in the same manner as in Example 6 except that the weight average particle diameter of the carrier used was changed from 55 μm to 45 μm. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Example 8
In Example 6, the cleaning property and the image quality were evaluated in the same manner as in Example 6 except that the weight average particle diameter of the carrier was changed from 45 μm to 28 μm. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

Comparative Example 1
In Example 1, the conductive cleaning blade used was changed to a urethane rubber blade (generally a normal blade) in which carbon black is not dispersed and does not exhibit conductivity, and connected to a metal plate that supports the blade. Evaluation of cleaning performance and image quality was the same as in Example 1 except that the DC power supply was disconnected and no voltage was applied, and the supply of the amorphous particles was stopped by removing the irregular particle supply device. Went. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.
In the initial state, the cleaning performance was poor and the state was extremely terrible, so the subsequent running was stopped.

Comparative Example 2
In Example 1, the conductive cleaning blade to be used was changed to a urethane rubber blade (usually blade: non-conductive) in which carbon black is not dispersed and does not exhibit conductivity, and connected to a metal plate that supports the blade. The cleaning property and the image quality were evaluated in the same manner as in Example 1 except that the application of the voltage was stopped by disconnecting the connected DC power source. The test conditions are shown in Table 1 below, and the evaluation results are shown in Table 2 below.

From the above evaluation results, the charged amorphous particles are charged by charging the irregular particles supplied from the deployed irregular particle supply device and applying a voltage to the conductive cleaning blade. Statically adsorbed and deposited on the opposite polarity clean blade edge to form a damming layer of irregular shaped particles. Spherical small-diameter toner does not enter from the clean blade edge, realizing good cleaning performance and good image quality It was confirmed that
Note that, under the conditions in the above embodiment, the smaller the ratio (D _f / D _t ) of the volume average particle diameter D _f of the irregularly shaped particles and the volume average particle diameter D _t of the spherical small diameter toner is, for example, 1.1, the cleaning is performed. Good circularity is large (for example, 0.98), the volume average particle diameter D _{f of} the spherical small-diameter toner is small (for example, 5.4 μm), and the weight average particle diameter of the carrier is small (for example, 25 μm), the image quality was better.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is a principal part expanded block diagram of the irregular-shaped particle supply apparatus 6 arrange | positioned at the image forming apparatus of this invention. FIG. 3 is an enlarged schematic view of a cleaning blade portion of a blade cleaning device 7 provided in the image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging device 2 Exposure device 3 Two-component developer type development device 4 Transfer device 5 Fixing device 6 Amorphous particle supply device 7 Blade cleaning device 7 ′ Conductive cleaning blade 8 Image carrier 9 Transfer material 21 Developing roller 22 Replenishment Roller 23 pulverized toner conveying material 24 pulverized toner regulating roller 25 case 26 metal spring 27 pulverized toner 31 conductive cleaning blade 32 image carrier 33 metal support 34 conductive adhesive 35 amorphous particles (pulverized toner)

Claims (9)

A developing device of a two-component developer system that develops at least a latent image formed on the image carrier with a spherical small-diameter toner, a transfer device that transfers a developed image on the developed image carrier to a transfer material, and after transfer In an image forming apparatus comprising a blade cleaning device having a cleaning blade for removing spherical small-diameter toner remaining on the surface of the image carrier,
The image forming apparatus includes an amorphous particle supply device that supplies charged amorphous particles that are deposited on the edge of the cleaning blade to dampen the residual spherical small-diameter toner,
The image forming apparatus, wherein the cleaning blade has conductivity and is applied with a voltage so as to be charged with a polarity opposite to that of the amorphous particles.   The image forming apparatus according to claim 1, wherein the charged amorphous particles are charged with a polarity opposite to that of a spherical small-diameter toner for developing a latent image. The ratio (D _f / D _t ) of the volume average particle diameter D _{f of the} irregular shaped particles and the volume average particle diameter D _t of the spherical small diameter toner for developing the latent image is 2.4> (D _f / D _t ). The image forming apparatus according to claim 1, wherein: The ratio (D _f / D _t ) of the volume average particle diameter D _{f of the} irregular shaped particles and the volume average particle diameter D _t of the spherical small diameter toner for developing the latent image is 1.2> (D _f / D _t ). The image forming apparatus according to claim 1, wherein:   5. The image forming apparatus according to claim 1, wherein the spherical small-diameter toner for developing the latent image has a volume average particle diameter of 9 μm or less and a circularity of 0.92 or more.   5. The image forming apparatus according to claim 1, wherein the spherical small-diameter toner for developing the latent image has a volume average particle diameter of 5.5 μm or less and a circularity of 0.98 or more.   The image forming apparatus according to claim 1, wherein a weight average particle diameter of a carrier of a developer used in the two-component developer method is 50 μm or less.   The image forming apparatus according to claim 1, wherein a weight average particle diameter of a carrier of a developer used in the two-component developer method is 30 μm or less. A developing device of a two-component developer system that develops at least a latent image formed on the image carrier with a spherical small-diameter toner, a transfer device that transfers a developed image on the developed image carrier to a transfer material, and after transfer Forming method using an image forming apparatus comprising: a blade cleaning device having a cleaning blade for removing spherical small-diameter toner remaining on the surface of the image bearing member; and an irregular-shaped particle supply device for damming the residual spherical small-diameter toner Because
Pressing the cleaning blade against the surface of the image carrier, depositing charged irregularly shaped particles on the edge of the cleaning blade to dampen the residual spherical small diameter toner,
An image forming method comprising forming an image by applying a voltage so that the cleaning blade is electrically conductive and is charged with a polarity opposite to that of the amorphous particles.

Images