JP3389930B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to an apparatus for forming an image using an electrophotographic process. More specifically, the present invention relates to an image forming apparatus including a toner recycling system that circulates toner between a developing device and a cleaning container to form an image.

[0002]

2. Description of the Related Art Hitherto, as an electrophotographic method, many methods have been proposed so far based on the Carlson process shown in US Pat. No. 2,297,691. Generally, an electrostatic latent image is formed on a photoconductor using a photoconductive substance, and then fine powder called'toner 'is selectively adhered to the latent image to develop the latent image. Image. This visualized toner is transferred to a transfer material such as paper, if necessary, and then fixed by heat and pressure, solvent vapor or the like to obtain an image-formed product. In this process,
After the toner was transferred onto the recording paper, the toner remaining on the photoconductor was often discarded as a waste toner after cleaning. However, from the viewpoints of reduction of running cost, prevention of contamination, operability, etc., many methods have been proposed in which the collected toner after cleaning is used again for development. For example, US Pat. No. 3634077 and US Pat.
No. 6,788,896, JP-A-55-45012, and JP-A-61-249061 disclose that the toner collected by the cleaning means is conveyed to the developing section. However, in these methods, the toner from the cleaning means cannot be uniformly supplied to the toner supply portion and the toner carrier, and the toner layer cannot be uniformly formed on the toner carrier. In addition, the toner is likely to be compressed and agglomerated during the transportation, and the toner is likely to be clogged. Further, since excessive mechanical stress is applied to the toner, the toner is easily broken. In addition, JP-A-3-2948
Japanese Patent Laid-Open No. 64 discloses that toner is recycled by using a toner containing an external additive obtained by treating silicone fine particles with a relatively large particle size.
However, in the above-mentioned conventional example, since the external additive has a polishing effect, when the toner is circulated, the circulation member is polished due to long-term use, and this is mixed into the toner, resulting in deterioration of image quality.
Further, the fluidity of the toner is insufficient for toner circulation, and the circulation cannot be performed smoothly. Further, due to contact between the toners during the toner circulation, the external additive may be peeled off or fallen off, toner aggregation and non-uniform charging are likely to occur, and the toner circulation cannot be performed for a long time, so that a good image is stably formed. There is a problem that you cannot do it.

Regarding external additives for toner, it has been widely practiced to use various kinds of surface-treated silica in order to impart fluidity to the toner and form a high quality image. For example, JP-A-61-277964 and JP-A-3-5956.
6, JP-A-2-287459 and the like disclose an image forming method using an external additive treated with silicone oil. However, all of them use magnetic toner and have problems such as poor fixing and image fog.

Further, in recent years, in an image forming apparatus using an electrophotographic process, in order to reduce the amount of ozone generated, contact charging or pressure contact transfer has been studied instead of conventional corona charging or corona transfer. For example, in JP-A-3-292264, toner filming on the contact charging member is prevented. However, the cleaning member has a problem in that only the external additive passes through the cleaning member and adheres to the contact charging member, resulting in uneven charging.

Further, Japanese Patent Application Laid-Open No. 1-195459 discloses a toner for improving the cleaning property of a transfer roller used for contact transfer. However, there is a problem that the reverse polarity toner transferred to the transfer roller by the cleaning bias when the paper is not passing is transferred to the back of the paper as a stain on the back of the paper.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. The object of the present invention is to circulate toner endlessly between a cleaning means and a developing means to develop the toner. The toner circulation for efficiently supplying the toner to the developing unit of the latent image carrier and for uniformly replenishing the toner to the toner carrier,
It is intended to form a high-quality image without causing toner aggregation or toner clogging, stably circulating the toner, and causing no image disturbance due to defective supply.

Further, the object of the present invention is to prevent crushing of toner, exfoliation of external additives, no contamination of foreign matter even after long-term use.
It is to form a high-quality image that does not fall off and is free from fog as in the initial stage.

Further, according to the present invention, an image forming apparatus which uses toner circulation and further performs contact charging and contact transfer, is small in size, has a low running cost, and can stably form a high quality image for a long period of time. Is to provide.

[0009]

The image forming apparatus of the present invention comprises a charging means for charging the latent image carrier to a predetermined potential with respect to the latent image carrier; An exposing unit that forms an electrostatic latent image pattern, a developing unit that applies toner to the electrostatic latent image pattern to visualize it, a transferring unit that transfers the developed toner to a recording material, and a latent image bearing member on the latent image carrier. Cleaning means for removing the residual toner, and a particle size of 0.
It is characterized by having a toner circulating means for circulating a toner containing inorganic fine particles treated with a silicone oil of 005 μm to 0.05 μm and replenishing it in a route for circulating the toner. Further, the toner circulating means is characterized in that the toner is circulated endlessly through the cleaning means and the developing means so that the toner falls from the cleaning means and drops to the developing means. The specific surface area of the treated inorganic fine particles is 60% or less of the specific surface area of the inorganic fine particles before the treatment, the polyester resin is used as the toner, and the charging unit is the latent image carrier. It is characterized in that it comprises a charging member in contact with the transfer means, and the transfer means comprises a transfer member in pressure contact with the latent image carrier.

[0010]

According to the above construction of the present invention, it is effective to circulate the toner after cleaning and the unused toner between the cleaning section and the developing section for the purpose of uniformly supplying the toner to the toner carrier. is there. However, this method requires the toner to solve the above-mentioned problems. Therefore, as a result of earnest research to solve this problem,
The present invention has been reached. It is known that the silicone oil used in the present invention generally has properties such as heat resistance, chemical and physical stability, water repellency, defoaming property and releasability. When a toner containing a silicone oil-treated external additive is used in toner circulation, due to the characteristics of silicone oil such as heat resistance, releasability, stability, and low surface energy, contact between toners by circulation works strongly. However, it is considered that the toner aggregate circulates and moves as if the liquid circulates without causing aggregation or toner adhesion. Also,
It is considered that the reason why toner deterioration does not easily occur even after long-term use is that the silicone oil is formed on the surface of the external additive on the coating film and the adhesion strength of the silicone oil is strong. The particle size of the external additive is preferably 0.5 μm or less. Furthermore, 0.005 to 0.05 μm is optimal. 0.5
If it exceeds μm, the fluidity of the toner is so poor that the toner cannot be circulated smoothly. Further, the external additive is easily peeled off, which deteriorates the image quality. On the other hand, when the thickness is 0.005 μm or less, the external additive is easily embedded in the resin, and continuous operation deteriorates fluidity, which is not preferable. Furthermore, the specific surface area of the external additive treated with silicone oil by the BET method is preferably 60% or less of the specific surface area of the external additive before the treatment. For example, when the specific surface area of the external additive before the treatment is 200 m ² / g, it is necessary to use the one having the specific surface area of 120 m ² / g or less after the silicone oil treatment. This indicates the degree of surface coverage with silicone oil, and it is considered that the larger the rate of change, the higher the coverage. As the resin used in the present invention, styrene acrylic resin, polyester resin, epoxy resin or the like which is generally used at present can be used, but polyester resin is preferable. The polyester resin has a stronger so-called gin property than other resins and is excellent in mechanical durability. Therefore, even if the toner is circulated endlessly, it is considered that the toner is hardly crushed. Further, even when the contact charging member and the pressure transfer member are used, a high quality image can be stably formed because, as described above, there is little toner deterioration such as embedding of the external additive and there is no fog.
Further, it is considered that the peeling of the external additive and the crushing of the toner are less and the adhesion to the image forming member is less.

The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these.

[0012]

FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, a latent image carrier 1
Is a photosensitive layer having organic or inorganic photoconductivity formed on a conductive support. The charging roller 2 charges the latent image carrier 1 while being driven by the latent image carrier 1 rotating in the direction of arrow 1a. The charging roller 2 is pressed toward the latent image carrier 1 by a pressing mechanism (not shown),
Bias is applied.

Next, a latent image carrier is carried by a light beam emitted from a light source such as a laser, scanned by a scanning mirror 41 rotated by a scanning motor 42, and made incident on a latent image carrier 1 by a lens 43 and a mirror 44. Image exposure is performed on the body 1 to form a latent image.

Next, the toner in the storage unit 14 for storing the toner in the developing unit 10 is coated on the surface of the developing roller 11 which is rotated by the supply roller 13 which rotates while stirring the toner, and the surface of the developing roller 11 is coated. The toner coated on the surface of the toner is rubbed against the plate-shaped regulating blade 12 made of, for example, non-magnetic or magnetic metal or resin to be thinned and frictionally charged. As the supply roller 13, it is possible to use one in which a foam member is concentrically arranged on the outer periphery of the shaft. As the developing roller 11, it is possible to use a roller in which a conductive elastic body is concentrically arranged on the outer circumference of the shaft. A bias is applied to the developing roller 11, the thinned toner layer is conveyed to the latent image carrier 1, and the developing roller 1
The latent image of the latent image carrier 1 is reversely developed at a nip portion formed by pressing the latent image carrier 1 into contact with the latent image carrier 1.

Further, although the latent image carrier 1 and the developing roller 11 are in contact with each other in FIG. 1, the present invention can be applied to the case of non-contact. Next, the toner image developed on the latent image carrier 1 is
The latent image carrier 1 is nipped and conveyed by the transfer roller 5 which is pressed toward the latent image carrier 1 by a pressing mechanism (not shown) and to which a bias having a polarity opposite to that of the toner image on the latent image carrier 1 is applied. Is transferred to the recording paper 3. After the recording paper 3 is sent to the transfer portion by the paper feed roller 4 and the toner image is transferred, the toner image is fixed by heating by the fixing roller 6 and is discharged by the paper discharge roller 7 in the direction of arrow 3a. It

Next, the toner remaining after transfer in the cleaning section 20 is scraped off by the cleaning blade 21 which is in pressure contact with the latent image carrier 1, and the cleaned latent image carrier 1 moves to the next image forming process again. Then, the above process is repeated again to continuously form images.

Next, the toner circulation will be described. The transport member 31 is circularly moved, and the image forming causes the developing unit 1 to move.
The toner in the storage unit 14 which is consumed and reduced at 0 is
When the toner amount decreases, the toner conveyed by the conveying member 31 that moves in the developing unit 10 almost at the same time drops and is automatically replenished, and the toner scraped by the cleaning unit 20 moves in the cleaning unit 20. The toner drops on the conveying member 31 and is conveyed to be used for replenishment of toner in the developing unit 10.

2A and 2B are views showing a conveying mechanism for circulating toner in the embodiment of FIG. 1, FIG. 2A is a top sectional view of the toner circulating and conveying mechanism of the present invention, and FIG. 2B is FIG.
It is a side surface sectional view of the cross section shown by the arrow b of (a). The toner circulating / conveying mechanism of the embodiment shown in FIG. 1 will be described in more detail with reference to FIG.

The conveying member 31 is a coil spring and is indicated by an arrow 31.
Drive is given in the direction of a by the drive gear 32 to which drive is transmitted from the drive shaft 33, and circularly moves through the supply window 34 communicating with the toner container 35, the developing unit 10, and the cleaning unit 20 in sequence. By driving the coil spring, which is the transport member 31, by engaging the groove of the drive gear 32 with the strand of the coil spring, the teeth of the drive gear 32 bite into the space in the coil spring in which toner is transported during driving. Therefore, the conveyance space of the coil spring that is the conveyance member 31 is narrowed, and the toner that is being conveyed is forcibly moved, and aggregation of the toner that is being conveyed is prevented.

The conveying member 31 that circulates first passes through a supply window 34 that communicates with a toner container 35 that is means for replenishing toner. The toner container 35 is arranged above the circulating movement path of the conveying member 31, and the toner in the toner container 35 is agitating member 37 to which the drive is transmitted from the drive shaft 33.
It is agitated by the rotation of and is in a fluid state. The toner container 35 is provided with a lid member 36, and the toner container 3
Toner 5 can be replenished with toner from the outside.

When the conveying member 31 passes through the supply window 34,
When the transport member 31 is not filled with toner, the toner in the toner container 35 falls from the supply window 34 to the transport member 31, but the transport space of the transport member 31 is narrowed by the drive gear 32, so that the toner is discharged. Even if the toner drops from the container 35, the amount of toner in the transport member 31 is kept smaller than the amount of toner that can be originally transported.

The transport member 31 which transports a certain amount of toner through the supply window 34 moves away from the drive gear to the developing section 10. When the toner in the storage unit 14 in the developing unit 10 is not stored in an amount that contacts the transport member 31,
The toner conveyed to the conveying member 31 falls into the storage unit 14. The conveyance member 31 crosses the developing unit 10 in the width direction of image formation, and the toner in the storage unit 14 is conveyed by the conveyance member 31.
If the toner in the storage unit 14 is stored in an amount that contacts the transport member 31, the toner that is being transported is held and moved as it is. Therefore, the amount of toner in the storage unit 14 becomes constant by the amount of contact with the conveying member 31 in the width direction of image formation due to the circulating movement of the conveying member 31.

The conveying member 31 which has passed through the supply window 34 and whose toner conveyance amount has been adjusted so that the toner is dropped in the developing unit 10 as necessary is guided by the inside of the casing to change its direction and pass through the cleaning unit 20. To do. The toner scraped off by the cleaning blade 21 in the cleaning unit 20 falls onto the conveying member 31 by the action of gravity, and unless the conveying member 31 is completely filled with the toner, the dropped toner is conveyed by the conveying member 31. Carried. As described above, the conveying member 31 is not filled with the toner because the toner conveying amount is adjusted in the state where the conveying space is narrowed by the driving gear 32, and the toner in the developing unit 10 and the cleaning unit 20 is not filled. Considering the balance, the developing unit 10 reduces the amount of toner developed on the latent image carrier, and the cleaning unit 20 does not transfer a part of the toner developed on the latent image carrier to the recording paper 3 and a small amount of transfer residue. Since the toner drops, the toner that falls from the cleaning unit 20 can be conveyed in the conveying member 31 after passing through the developing unit 10. Therefore, the toner falling in the cleaning unit 20 is reliably transported by the transport member 31.

The transport member 31 that has passed through the supply window 34, the developing section 10 and the cleaning section 20 circulates again to the supply window 34, and the toner is replenished from the toner container 35 as necessary, and the operation is repeated. As the conveying member 31 used as the toner circulating / conveying means of the present invention, a belt, a chain or the like capable of circulating movement can be used.

As described above, according to the present invention, it is possible to form an image by circulating the toner between the developing section and the cleaning section.

Now, the charging roller 2 will be described in more detail. The charging roller 2 has a conductive rubber layer on a metal shaft, and a two-layer roller having a high resistance layer on the outer periphery of the conductive rubber layer is brought into pressure contact with the latent image carrier 1 at a linear pressure of several gf / mm. , Latent image carrier 1 using discharge or charge injection
Is charged to a predetermined potential. As for the charging bias, for example, when the latent image carrier 1 is charged to -600V, a discharge starting voltage of -570V is added to this voltage-1.
When 170 V is applied and an AC component is superimposed, an AC voltage of about ± 600 V is superimposed on the DC component described above. Further, the charging roller 2 may be rotated at the same peripheral speed as the latent image carrier 1 or may be rotated or fixed at a different peripheral speed. Further, it goes without saying that the charging roller 2 does not easily adhere to the external additive of the toner, does not contaminate the latent image carrier 1, does not easily stick to it, does not easily wear, and has a smooth surface to carry the latent image. Properties such as good contact with the body 1 are required. In addition to this, a single-layer elastic conductive roller having a resistance distribution in which the resistance increases as the surface approaches a single-layer conductive rubber layer, or a seepage prevention layer, a resistance adjusting layer other than the above resistance layer , An elastic conductive multilayer roller provided with a protective layer, etc., an elastic conductive roller using a foam having a small resistance change, or a film-like elastic in which a resistive resin layer is formed on a thin metal plate as a form other than the roller. The latent image carrier 1 can also be charged to a predetermined potential by using a body, an elastic conductive film formed of a resistive resin, or an elastic conductive brush such as a fur brush. In particular, when the resistance of the charging roller 2 is set to 10 ⁶ to 10 ⁹ Ω, overcurrent is generated in the pinholes even if the latent image carrier 1 has a pinhole in each environment from high temperature high humidity to low temperature low humidity. It does not flow, and a sufficient charging time can be secured from the time constant of charging, and charging with less uneven charging can be performed.

The roller resistance is to measure the resistance of the roller by pressing the conductive plate with a load of 500 gf on both shaft ends and connecting a resistance meter between the shaft of the roller and the conductive plate. However, the applied voltage during resistance measurement is 10 VDC.

Next, the transfer roller 5 will be described in more detail. The transfer roller 5 is an elastic conductive roller provided with a conductive foam layer on a metal shaft, and has a linear pressure of several gf.
/ Mm, the latent image carrier 1 is stably pressed against the recording paper 3. As the transfer bias, for example, +600 V to +2000 V is applied, and when the transfer roller 5 is in direct contact with the latent image carrier 1, the transfer bias is cut off or a cleaning bias is applied. The transfer roller 5 is rotated at substantially the same peripheral speed as the latent image carrier 1. Further, it goes without saying that the transfer roller 5 does not easily adhere to the toner, does not contaminate the latent image carrier 1, does not easily stick to it, does not easily wear, and has a uniform and flexible surface, which is latent image carrier 1. It is necessary to have characteristics such as good contact with. In addition to this, as the transfer roller, a single-layer elastic conductive roller using a conductive foam with a skin, or a multilayer elastic conductive multi-layer roller provided with a seepage prevention layer, a resistance adjusting layer, a protective layer, etc. When used, the recording paper 3 can be brought into close contact with the latent image carrier 1 to form a high-quality transfer image free from toner scattering and voids. Particularly, regarding the resistance of the transfer roller 5,
^{When it is set to 5} to 10 ⁸ Ω, in each environment from high temperature and high humidity to low temperature and low humidity, sufficient transfer time can be secured from the transfer time constant and good transfer can be performed, and the transfer bias can be as low as possible. Thus, the influence of the transfer on the electrostatic latent image pattern can be reduced.

Next, the toner used in this embodiment will be described in detail. As the toner used in the image forming apparatus, magnetic and non-magnetic toner having a volume average particle size of 5 to 20 μm, which is produced by a general kneading and pulverizing method, a spray drying method, and a polymerization method can be used. The toner composition is not particularly limited, and a general toner composition can be used. For example, as the binding resin, polystyrene and copolymers such as hydrogenated styrene resin, styrene / isobutylene copolymer, ABS resin, ASA resin,
AS resin, AAS resin, ACS resin, AES resin, styrene / P chlorostyrene copolymer, styrene / propylene copolymer, styrene / butadiene crosslinked polymer, styrene / butadiene / chlorinated paraffin copolymer, styrene / allyl / alcohol Copolymer, styrene / butadiene rubber emulsion, styrene / maleic acid ester copolymer, styrene / isobutylene copolymer, styrene /
Maleic anhydride copolymer, acrylate resin or methacrylate resin and its copolymer, styrene
Acrylic resins and their copolymers such as styrene
Acrylic copolymer, styrene / diethylamino / ethylmethacrylate copolymer, styrene / butadiene / acrylic acid ester copolymer, styrene / methylmethacrylate copolymer, styrene / n-butylmethacrylate copolymer, styrene / diethylamino -Ethyl methacrylate copolymer, styrene-methyl methacrylate-n-butyl acrylate copolymer, styrene-methyl methacrylate-butyl arylate-N- (ethoxymethyl) acrylamide copolymer, styrene-glycidyl methacrylate copolymer , Styrene / butadiene / dimethyl / aminoethyl methacrylate copolymer, styrene / acrylic acid ester / maleic acid ester copolymer, styrene / methyl methacrylate / 2-ethyl acrylate Copolymer, styrene / n-butyl arylate / ethyl glycol methacrylate copolymer, styrene / n-butyl methacrylate / acrylic acid copolymer, styrene / n-butyl methacrylate / maleic anhydride copolymer, styrene -Butyl acrylate-isobutyl maleic acid half ester-divinylbenzene copolymer, polyester and its copolymer, polyethylene and its copolymer, epoxy resin, silicone resin, polypropylene and its copolymer, fluorine resin, polyamide resin, poly It is possible to use one kind of vinyl alcohol resin, polyurethane resin, polyvinyl butyral resin or the like, or a blend of two or more kinds. However, in order to smoothly circulate the toner and form a good image for a long period of time, it is preferable to use a polyester resin having excellent mechanical durability.

As the colorant, a black dye / pigment such as carbon black, spirit black or nigrosine is used. For color, phthalocyanine, rhodamine B
Dyes such as lake, solar pure yellow 8G, quinacridone, polytungstophosphoric acid, induslen blue, and sulfonamide derivatives can be used. Furthermore,
As a dispersant, metal soap, polyethylene glycol or the like can be added, and as a charge control agent, an electron-accepting organic complex, chlorinated polyester, nitrofunnic acid, quaternary ammonium salt, pyridinyl salt or the like can be added. As the magnetic agent, fine particles having a particle size of 5 μm or less, which are chemically stable when dispersed in a binder resin, are preferable. For example,
Fe, Co, Ni, Cr, Mn metal powder, Fe ₃ O ₄ , F
e ₂ O ₃ , Cr ₂ O ₃ , metal oxides such as ferrite, alloys containing ferromagnetism by heat treatment such as alloys containing manganese and copper, etc. can be used, and even if a pretreatment such as a coupling agent is performed in advance. I do not care. Further, polypropylene wax, polyethylene wax or the like can be added as a release agent. Further, as other additives, zinc stearate, zinc oxide, cerium oxide and the like can be used.
Further, various kinds of inorganic fine particles can be used as the external additive. For example, it is effective to use metal oxides such as silica, alumina and titanium oxide, and composite oxides thereof. The particle diameter of the external additive is preferably 0.5 μm or less, and more preferably 0.05 μm or less in consideration of peeling, desorption of the external additive, suppression of polishing effect, fluidity of the toner and the like. The silicone oil and silicone varnish used as the surface treatment agent for the external additive are not particularly limited, and ordinary ones can be used. For example, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl silicone oil, alkyl silicone oil, fluorosilicone oil, methyl hydrogen silicone oil, silanol group-containing silicone oil and the like can be used. A known method can be used for treating the inorganic fine particles with silicone oil and silicone varnish. For example, a powder mixer such as a Henschel mixer,
It can be processed by a spray dryer using a spray dryer. The treatment amount of the silicone oil and silicone varnish suitable for the present invention to the inorganic fine particles is defined by measuring the specific surface area before and after the treatment. The specific surface area was measured by the BET method using nitrogen adsorption. In the present invention, the specific surface area after the treatment is preferably 60% or less of the specific surface area before the treatment. That is, it is preferable that the specific surface area be small. 60
%, The degree of surface treatment with silicone oil and silicone varnish is insufficient, and toner circulation cannot be performed smoothly and for a long period of time. The content of the external additive treated with silicone oil and silicone varnish with respect to the toner is preferably 0.1 to 5 wt%. Further, the volume resistance of the toner used in the present invention is preferably 10 ¹⁷ Ωcm or more. To measure the resistance, toner is pressed into pellets with a thickness of 0.5 mm, electrodes are placed on the top and bottom, and 1 Kg / cm.
The current value when a voltage of 250 V was applied with the load of ² applied was determined and converted to a volume resistance value. The measurement was performed in a dry desiccator which was replaced with a nitrogen atmosphere.

Specific examples are shown below.

(Specific Example 1) The toner used in this specific example 1 will be described. The toner composition is shown below.

Polyester resin 88 wt% Polypropylene wax 3 wt% Charge control agent 2 wt% Carbon black 6 wt% Using the raw materials having the above composition, kneading with a screw extruder,
Coarsely crush. Next, it was finely pulverized with a jet pulverizer and classified to prepare toner mother particles having a volume average particle diameter of 9 μm.

Next, a particle size of 0.012 is obtained as the inorganic fine particles.
An external additive was prepared by surface-treating dimethyl silicone oil on μm silica. The specific surface area of this external additive according to the BET method is 200 m ² / g before the treatment and 50 after the treatment.
% Was 100 m ² / g. Next, this external additive 0.
8 wt% was added to the surface of the toner mother particles by a Henschel mixer to prepare a toner. Toner resistance is 5 ×
It was 10 ¹⁷ Ωcm. Next, an image was formed by the image forming apparatus shown in FIG. As a result, there is no toner aggregation, toner clogging, etc., and toner circulation can be performed smoothly,
There was no image disturbance due to supply failure or the like. Also, 10
Even after running printing of 000 sheets, a high-quality image free from fog and the like could be stably formed. Also, the same test is performed under high temperature and high humidity of 35 ° C-65% RH and 10 ° C.
It was carried out at a low temperature and low humidity of -15% RH, but there was no significant deterioration in image quality, and stable and good images could be formed. Thus, by using the external additive treated with silicone oil, toner is circulated, and even in an image forming apparatus using a charging roller and a transfer roller, a stable and good image can be formed for a long period of time. You can

(Specific Example 2) Next, an external additive in which the particle diameter of silica in Example 1 was changed was prepared, and a toner was prepared in the same manner as in Example 1 except for the above, and the image forming apparatus shown in FIG. Used to form an image. The results are shown in Table 1.

[0036]

[Table 1]

As is clear from the results shown in Table 1, when the particle size of the external additive exceeds 0.5 μm, the toner cannot be circulated favorably, and the image quality is further deteriorated due to poor supply, peeling external additive and the like. Is significantly deteriorated. It is considered that this is because the fluidity is low and the external additive peels off and adheres to the photoconductor, the charging roller and the like. Therefore, the particle size of the external additive is 0.5
It is preferably not more than μm, more preferably not more than 0.05 μm.

(Specific Example 3) Next, using the external additive of Specific Example 1, those having different specific surface areas after treatment with dimethyl silicone oil were prepared. Others were the same as in Example 1 except that a toner was prepared and an image was formed using the image forming apparatus shown in FIG. The results are shown in Table 2.

[0039]

[Table 2]

As is clear from the results shown in Table 2, when the reduction rate of the specific surface area after the treatment exceeds 60%, the toner circulation cannot be performed stably and smoothly. It is considered that this is because the surface of the external additive is not sufficiently coated with silicone oil. Therefore, it is necessary to treat with silicone oil so that the specific surface area after treatment is 60% or less of the specific surface area before treatment.

Although the image forming apparatus shown in FIG. 1 and the silicone oil-treated external additive-containing toner shown in the specific examples have been described in the present embodiment, the present invention is not limited to these. It can be applied to all processes that perform circulation. It is especially effective when applied to printers, copiers, facsimiles and displays.

[0042]

As described above, according to the present invention, the image forming apparatus having the means for circulating the toner endlessly between the cleaning means and the developing means and replenishing the toner in the path for circulating the toner. The toner used for the toner contains inorganic fine particles treated with silicone oil and silicone varnish, the particle size of the inorganic fine particles is 0.5 μm or less, and the specific surface area after the treatment with silicone oil is the same as that before the treatment. It should be 60% or less, and by using a polyester resin having high mechanical durability as the toner resin, toner aggregation and toner clogging do not occur, and toner circulation is performed smoothly and stably for a long period of time. Therefore, it is possible to form a high-quality image without image disturbance due to defective supply or the like.

Further, no foreign matter is mixed in for a long period of time,
The objective is to stably form a high-quality image free from fog, as in the initial stage, without crushing the toner, peeling off or dropping off the external additive.

Further, in the present invention, toner circulation can be used, and contact charging and pressure transfer can be further performed. As a result, it is possible to provide an epoch-making image forming apparatus which is small in size, has a low running cost, and can form a high quality image.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an image forming apparatus of the present invention.

FIG. 2A is a top sectional view of the toner transport mechanism of the embodiment of FIG. 2B is a side cross-sectional view of the cross section indicated by the arrow b in FIG.

[Explanation of symbols]

1 Latent image carrier 2 charging roller 3 recording paper 4 paper feed rollers 5 Transfer roller 6 fixing roller 7 Paper ejection roller 10 Development Department 11 Developing roller 12 Regulation blade 13 Supply roller 14 Storage 20 Cleaning section 21 cleaning blade 31 Transport member 32 drive gear 33 Drive shaft 34 Supply window 35 toner container 36 Lid member 37 Stirring member 41 scanning mirror 42 scanning motor 43 lens 44 mirror

Continuation of front page (56) Reference JP-A-3-59565 (JP, A) JP-A-4-366865 (JP, A) JP-A-63-214782 (JP, A) JP-A-4-353885 (JP , A) JP-A-6-3853 (JP, A) JP-A-6-194872 (JP, A) JP-A-4-204750 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G03G 9/08 G03G 15/08 G03G 21/10

Claims (6)

(57) [Claims] 1. A charging unit for charging the latent image carrier to a predetermined potential with respect to the latent image carrier, an exposure unit for irradiating the latent image carrier with light to form an electrostatic latent image pattern, and the static unit. A developing unit that applies toner to the latent image pattern to visualize it.
Transfer means for transferring the developed toner to a recording material, cleaning means for removing the toner remaining on the latent image carrier, and a particle size of 0.005 μm to 0..m between the cleaning means and the developing means. An image forming apparatus characterized by having a toner circulating means for circulating a toner containing inorganic fine particles treated with 05 μm of silicone oil and replenishing it in a route for circulating the toner. 2. The toner circulating means circulates endlessly through the cleaning means and the developing means so that the toner falls from the cleaning means and drops to the developing means. The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 1, wherein the specific surface area of the inorganic fine particles treated with the silicone oil is 60% or less of the specific surface area of the inorganic fine particles before the treatment. 4. The image forming apparatus according to claim 1, wherein the toner uses a polyester resin. 5. The image forming apparatus according to claim 1, wherein the charging unit comprises a charging member that contacts the latent image carrier. 6. The image forming apparatus according to claim 1, wherein the transfer means comprises a transfer member which is in pressure contact with the latent image carrier.