JP2010061082A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of toner with the lapse of time and to obtain a high-quality image even with the lapse of time by stably electrifying the toner while suppressing stress given to the toner in a one-component developing system. <P>SOLUTION: The toner is supplied to a toner carrying sleeve 3 which conveys the toner to a developing area without pressing the toner thereon, and then the toner is electrified by allowing a charger 8 functioning as the toner electrifying member arranged to provide a gap between the charger 8 and a surface of a toner layer on the toner carrying sleeve on a more upstream side than the developing area to discharge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and the like, and a developing device employed therein.

  Conventionally, a one-component developing device has been widely used as a developing unit of an image forming apparatus. As a typical configuration of the one-component developing device, a flexible sponge roller is used as a supply member for supplying toner to the toner carrier, and the toner is rubbed by pressing the toner against the toner carrier with the sponge roller. The toner is supplied onto the toner carrier while being charged (see FIG. 8). In addition, a regulating member that regulates the amount of toner carried on the toner carrying member is provided, and the toner is pressed against the toner carrying member by the regulating member, so that the toner layer is uniformly thin while frictionally charging the toner (see FIG. 9). In this way, the charged and thinned toner is transported to a portion facing the latent image carrier by the movement of the surface of the toner carrier and developed.

  In this one-component developing device, a strong stress is applied to the toner by pressing the toner against the toner carrying member at the time of supplying the toner by the supply member and at the time of restriction by the restriction member, and causes toner deterioration over time. Specifically, the toner is made of resin as a base material (binder), and additives such as silica and titanium called fluidized particles are attached around it. However, the additive is buried inside the base material (binder) due to stress. Fluidity decreases. Due to the decrease in fluidity, the toner tends to adhere to the toner carrier and the regulating member. In addition, the toner carrier and the regulating member are subjected to frictional heat generated at the supply unit and the regulating unit, so that the adhering toner is not dissolved and peeled off, so-called toner carrier filming or toner fixing to the regulating member. This occurs. In such a situation, the frictional charging of the toner is hindered over time, a predetermined polarity and charge amount cannot be obtained, and background staining is likely to occur, development efficiency is lowered, and image quality is lowered.

  In particular, in recent years, it has been desired to reduce the energy consumption of the image forming apparatus due to environmental problems, and there is a tendency to lower the melting temperature of the toner so as to reduce the energy at the time of toner fixing with a large amount of energy consumption. Further, in many cases, a wax material is mixed and added to the toner in order to improve releasability at the time of fixing. Changes in the characteristics of these toners also contribute to the above problem.

  In view of this, there has been proposed one that suppresses stress applied to the toner. For example, in Patent Document 1, a supply member is disposed in a non-contact manner with respect to a toner carrier in a toner supply unit, and a precharged toner is electrostatically supplied from the supply member to the toner carrier with a potential difference. In addition, there is a description that the toner is made to be a uniform thin layer while the charging amount of the toner is further stabilized by performing frictional charging by a regulating member.

In addition, a method for charging toner by a method other than frictional charging has been proposed. For example, in Patent Document 2, a conductive toner is used, and a charge is applied to the conductive toner contained in the toner container by applying a voltage to the inner wall of the toner container coated with a conductive paint as a charge applying member. Then, after charging the toner, the toner is supplied by flying to a grounded toner carrier.
JP 2003-084565 A Japanese Patent Laid-Open No. 9-300685

  In the developing device disclosed in Patent Document 1, although the stress in the supply unit can be suppressed, the stress in the regulating unit cannot be suppressed, and it cannot be said that the stress reduction effect is sufficient. In addition, in the device that charges the toner by applying a charge to the toner using the charge applying member of Patent Document 2, the effect of suppressing the stress is great, but the toner is charged by charging the bulk toner contained in the container. Therefore, it is difficult to obtain a sufficient and stable toner charge amount as compared with conventional frictional charging.

  The present invention has been made in view of the above problems, and the object of the present invention is to use the one-component development method to stably deteriorate the toner over time by charging the toner stably while suppressing the stress applied to the toner. It is an object of the present invention to provide a developing device and an image forming apparatus capable of suppressing the above and obtaining a high-quality image over time.

In order to achieve the above object, a first aspect of the present invention provides a toner carrier that carries toner accommodated in the apparatus and conveys the toner to a developing region that is opposite to the latent image carrier, and the toner carrier. And a toner charging member that charges the toner on the toner carrier upstream of the development region with respect to the toner transport direction of the toner, the toner contained in the device is partly contained in the toner carrier. The toner is carried on the toner carrier by contacting without being pressed, and the toner charging member is disposed with a gap with respect to the surface of the toner layer on the toner carrier. It is.
According to a second aspect of the present invention, there is provided the developing device of the first aspect, further comprising toner fluidizing means for fluidizing the toner accommodated in the apparatus, and the toner fluidized by the toner fluidizing means. It is characterized in that it is supported on the surface.
According to a third aspect of the present invention, in the developing device according to the first or second aspect, the toner charging member is a dischargeable charger.
According to a fourth aspect of the present invention, in the developing device according to the first or second aspect, the toner charging member is a dischargeable roller.
According to a fifth aspect of the present invention, in the developing device according to any one of the first, second, third, and fourth aspects, the development electric field is formed between the toner carrier and the latent image carrier in the development region. An electric field forming means is provided.
According to a sixth aspect of the present invention, in the developing device according to any one of the first, second, third, and fourth aspects, the second toner carrier disposed between the toner carrier and the latent image carrier; A transition electric field forming means for forming a transition electric field for transferring the toner charged by the toner charging member from the toner carrier to the second toner carrier; the second toner carrier; and the latent image carrier; A developing electric field forming means for forming a developing electric field is provided between the two.
According to a seventh aspect of the present invention, in the developing device according to any one of the second, third, fourth, fifth, and sixth aspects, the toner fluidizing means is a stirring member disposed in a device that accommodates toner. It is a feature.
According to an eighth aspect of the present invention, in the developing device according to any one of the second, third, fourth, fifth, and sixth aspects, the toner fluidizing means is a vibrating member that abuts an apparatus housing that contains toner. It is what.
According to a ninth aspect of the present invention, in the developing device according to any one of the first, second, third, fourth, fifth, sixth, seventh, or eighth aspects, the toner carrying member is stretched by a plurality of cylindrical members. Among the plurality of cylindrical members, a cylindrical member that stretches the toner carrier at a position in contact with the toner has irregularities on the surface.
According to a tenth aspect of the present invention, there is provided a latent image carrier that carries an electrostatic latent image, an electrostatic latent image forming unit that forms an electrostatic latent image on the latent image carrier, and the latent image carrier. In the image forming apparatus including the developing means for developing the electrostatic latent image, the toner contained in the apparatus is carried as the developing means and conveyed to a developing area which is a portion facing the latent image carrier. A toner carrying member for carrying the toner on the toner carrying member by bringing the toner contained in the apparatus into contact with a part of the toner carrying member without pressing the toner carrying member. Adopting a developing device that charges the toner layer on the toner carrier by a toner charging member arranged with a gap with respect to the surface of the toner layer on the toner carrier upstream of the development region with respect to the direction. It is a feature.

  In the present invention, the toner contained in the apparatus is brought into contact with the toner carrier without being pressed. Since the toner is not pressed against the toner carrier, frictional charging is not performed and the toner is almost uncharged. Since toner that is almost uncharged does not have electrostatic restraining force due to the toner carrier, the adhesion force on the surface of the toner carrier and the van der Waals force between the toner adhering to the surface of the toner carrier and other toners. To be carried on the toner carrier. At this time, the amount of toner that can be carried by the toner carrier is smaller than that carrying the charged toner because there is no electrostatic binding force between the toner and the toner carrier, and the toner is thin on the toner carrier. It becomes a layer state. Then, the toner is charged without stress from the toner charging member disposed in a non-contact manner on the surface of the toner layer on the toner carrying member that is almost uncharged. Here, since the toner layer on the toner carrying member is a thin layer, uniform charging can be performed as compared with the case where the toner layer is a thick layer or the toner is a lump. That is, in the conventional developing device, the toner charged by the supply unit is carried on the toner carrying member in a thick layer state, the regulating member is pressed by the regulating member to regulate the toner carrying amount, and the toner is thinned and conveyed to the developing region. . On the other hand, in the present invention, the toner that is almost uncharged is supported in a thin layer state without being frictionally charged, and the toner layer in the thin layer state is charged with no stress from a non-contact toner charging member and developed. Transport to area. As described above, the toner deterioration over time can be suppressed by stably charging the toner by a method other than frictional charging while suppressing the stress.

  As described above, according to the present invention, by one-component development system, the toner is stably charged while suppressing the stress applied to the toner, thereby suppressing the deterioration of the toner with the lapse of time and obtaining a high-quality image even with the lapse of time. There is an excellent effect of being able to.

  Hereinafter, embodiments of an image forming apparatus to which the present invention is applied will be described. In the image forming apparatus according to the present invention, a one-component developing device for contact or non-contact development is used. For example, a contact developing device using an aluminum sleeve, a contact developing device using a conductive rubber belt, or a non-contact using a developing sleeve in which a conductive resin layer containing carbon black, metal filler, etc. is formed on the surface of an aluminum base tube. A developing device or the like.

<First embodiment>
The one-component developing device according to the first embodiment charges toner by discharging a toner charging member without applying stress due to frictional charging. FIG. 1 is a schematic configuration diagram of a one-component developing apparatus according to the present embodiment. In the developing device 2, a toner carrying sleeve 3 that is rotatable as a toner carrying member is disposed so as to face the photosensitive member 1 that is a latent image carrying member. Below the developing device 2, a hopper portion 4 that accommodates the toner 12 is formed, and the lower portion of the toner carrying sleeve 3 is disposed so as to contact the toner in the hopper portion 4. The hopper portion 4 contains 100 to 150 [g] of toner.

  In the hopper portion 4, an agitator 5 with blades around the rotation shaft is disposed so as to stir the toner 12 in the vicinity of the toner carrying sleeve 3 to be accommodated. By this agitation, the toner 12 in the vicinity of the toner carrying sleeve 3 is released even if it is initially in an aggregated state, and the distance between the toners is increased. As a result, the fluidity of the toner 12 in the vicinity of the toner carrying sleeve 3 is high and the fluidization state is easily achieved. The agitator 5 stirs and fluidizes the toner, and is not disposed close to the toner until it is pressed against the toner carrying sleeve 3.

  The toner carrying sleeve 3 comes into contact with the fluidized toner in the hopper portion 4 to form a toner supply region. In this toner supply region, the toner in the hopper 4 is not pressed against the toner carrying sleeve 3, and therefore frictional charging does not occur and the toner is almost uncharged. Since the toner in an almost uncharged state does not generate an electrostatic restraining force by the toner carrying sleeve 3, the toner carrying sleeve surface adhesion force and the van der Waals of the toner adhering to the toner carrying sleeve 3 surface and other toners. The toner is carried on the toner carrying sleeve 3 by the force. In other words, the conventional developing device supplies toner while pressing the toner against the toner carrying sleeve 3 by a toner supply member and frictionally charges the toner, or supplies charged toner electrostatically. In such a conventional developing device, since the charged toner is carried on the toner carrying sleeve 3 with a force including an electrostatic restraining force, the carrying amount increases and the layer thickness becomes thick. On the other hand, in the developing device 2 of the present embodiment, the toner that is almost uncharged is carried with a force that does not include the electrostatic restraining force from the toner carrying sleeve 3, so that the toner is smaller than the conventional developing device. The layer becomes a thin layer.

  Furthermore, since the toner is in a fluidized state, the probability of contact with the toner carrying sleeve 3 increases. Further, since the relationship of the adhesion force of the toner to the toner carrier> the adhesion force between the toners is established, the toner falls when the toner carrying sleeve 3 floats from the toner surface accommodated in the hopper portion 4, so that the toner layer becomes thick. It is not a layer, specifically, it is a thin layer of 1 to 3 layers.

Further, with respect to the rotation direction of the toner carrying sleeve 3, a charger 8 as a toner charging member having a gap with the surface of the toner layer is disposed downstream of the toner supply region and upstream of the development region. As the toner carrying sleeve 3 rotates, the thin toner layer conveyed to the portion facing the charger 8 is charged by being charged by the discharge of the charger 8. The charger 8 is preferably a scorotron, and a DC voltage is applied to the wire and the grid. In this embodiment, −6 [kV] is applied to the wire and −50 [V] is applied to the grid. Here, since the toner carrying sleeve 3 is formed of a low resistance material, the electric charge that does not fall on the toner flows to the toner carrying sleeve 3. Under this condition, the toner thin layer after passing through the charger 8 had an adhesion amount of 0.3 [mg / cm ² ] and an average charge amount of about −9 [μC / g]. FIG. 2 shows the charge amount distribution before passing through the charger 8 and the charge amount distribution after passing through the charger 8. The charge amount distribution is data obtained by sampling 3000 toners using an E-Spart Analyzer manufactured by Hosokawa Micron Corporation. Although charged before the charger 8 is included, this is not the one that is actively charged with the toner when supplied to the toner carrying sleeve 3 and frictionally charged, but one that is collected from the toner carrying sleeve 3 or This is considered to be due to the inclusion of a small but charged material due to contact with the agitator 5. In any case, by being charged by the charger 8, it is possible to charge to a desired charge amount on the toner carrying sleeve 3 without applying stress.

  The toner charged by the charger 8 is conveyed to the development area by the rotation of the toner carrying sleeve 3. An electrostatic latent image corresponding to a negative-positive process is formed on the photoreceptor 1 by a known charging and exposure process (not shown). In the developing area, a developing electric field is formed between the toner carrying sleeve 3 and the photoreceptor 1, and the toner on the toner carrying sleeve 3 moves to the image portion of the electrostatic latent image on the photoreceptor 1.

  The toner image developed on the photoreceptor 1 is then subjected to a transfer and fixing process to form an image. A collecting bias for collecting the toner on the toner carrying sleeve 3 is applied to the downstream portion of the developing area, and a collecting roller 6 as a collecting member that rotates in the same speed and in the same direction as the toner carrying sleeve 3 is in contact with the collecting bias. Yes. The undeveloped toner is collected by the collection roller 6 and returned to the hopper unit 4 as appropriate.

FIG. 3 shows the experimental results comparing the toner additive burying ranks over time between the developing device 2 of the present embodiment and the conventional developing device (see FIG. 7) for charging toner by frictional charging. In the developing device 2 of the present embodiment, the additive embedding rank is maintained at 4.7 even when 100 [k sheets (thousand sheets)] is exceeded, whereas in the conventional developing device, 20 [k sheets] Rank 3 and Rank 50 for 50 [k]. Thus, the mechanical stress can be suppressed by supplying the toner to the toner carrying sleeve 3 and applying the charge of the toner by the non-contact type toner charging member without using the conventional triboelectric charging. The image quality can be maintained without deterioration even over time.

Next, the toner carrying sleeve 3 employed in the developing device 2 shown in FIG. 1 will be described. In FIG. 1, a rigid drum-shaped photoconductor 1 based on an aluminum tube is used as the photoconductor 1. Therefore, the toner carrying sleeve 3 is made of an elastic rubber material. The hardness is in the range of 10 to 70 ° (JIS-A).

  The toner carrying sleeve 3 is obtained by applying a surface coat layer to a base layer made of a rubber material. Examples of the rubber material for the base layer include silicon, butadiene, NBR, hydrin, and EPDM. Further, in order to further reduce the hardness of the toner carrying sleeve 3, an endless belt using rubber or a thin metal plate can be used.

Examples of the material for the surface coat layer include a material containing a resin such as silicon, acrylic, and polyurethane, and rubber. Another example of the material is a material containing fluorine. A so-called Teflon (registered trademark) material containing fluorine has a low surface energy and excellent releasability, and therefore toner filming with time is extremely difficult to occur. Also, as general resin materials that can be used for the material of the surface coat layer, polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), tetrafluoroethylene / hexafluoropropylene polymer (FEP) ), Polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) Etc. In order to obtain conductivity, a conductive material such as carbon black is often contained in this. In order to coat the toner carrier more uniformly, another resin may be mixed.

The electrical resistance sets the bulk volume resistivity including the surface coat layer, and adjusts the resistance of the base layer so that it can be set to 10 ³ to 10 ⁸ [Ω · cm]. Since the volume resistivity of the base layer used in this embodiment is 10 ³ to 10 ⁵ [Ω · cm], the volume resistivity of the surface layer may be set slightly higher.

  The diameter of the toner carrying sleeve 3 is preferably 10 to 30 [mm]. In the present embodiment, one having a diameter of 16 [mm] is used. Further, the surface of the toner carrying sleeve 3 was appropriately changed to have a roughness Rz (10-point average roughness) of 1 to 4 [μm]. The range of the surface roughness Rz is 13 to 80% with respect to the volume average particle diameter of the toner 10 and is a range in which the toner 12 is conveyed without being buried in the surface of the toner carrying sleeve 3.

Further, the toner used in the present embodiment is advantageous in that the volume average particle diameter is 4 to 8 [μm] in order to realize a high-quality image. The weight average particle diameter of the toner is 4 to 8 [μm], more preferably 5 to 7 [μm]. If the weight average particle diameter is less than 4 [μm], problems such as contamination inside the machine due to toner scattering during long-term use, image density reduction in a low-humidity environment, poor photoconductor cleaning, etc. are likely to occur, and there are concerns about the effects on the human body. The When the weight average particle size exceeds 8 [μm], the resolution of fine spots of 100 [μm] or less is not sufficient, and the image quality tends to be inferior due to many scattering to non-image areas.

Details of the toner are shown below. As resins, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene acrylic resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, polyethylene resin, silicon resin, butyral resin, terpene There are resins, polyol resins and the like. Examples of vinyl resins include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers thereof: styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer. Polymer, styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methacrylic copolymer Acid methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Coalescence, styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene copolymers such as copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate and the like.

The polyester resin is composed of a dihydric alcohol as shown in the following group A and a dibasic acid salt as shown in the group B, and further a trihydric or higher alcohol as shown in the group C or Carboxylic acid may be added as a third component. Group A: ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4 butanediol, neopentyl glycol, 1,4 butenediol, 1,4-bis (hydroxymethyl) cyclohexane Bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,2′-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -2,2′-bis (4 -Hydroxyphenyl) propane and the like.
Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, linolenic acid, or These acid anhydrides or esters of lower alcohols.
Group C: Trivalent or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol, and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid. As the polyol resin, an alkylene oxide adduct of an epoxy resin and a dihydric phenol, or a compound having one active hydrogen in the molecule that reacts with the glycidyl ether and the epoxy group, and an active hydrogen that reacts with the epoxy resin in the molecule. There are those obtained by reacting two or more compounds.

Moreover, the following are used as a pigment.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel yellow, navel yellow, naphthol yellow S, hansa yellow G, hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. .
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.
Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, fast sky blue, and indanthrene blue BC.
Examples of green pigments include chrome green, chromium oxide, pigment green B, and malachite green lake.
These can use 1 type (s) or 2 or more types. Especially for color toners, uniform dispersion of good pigments is essential. Instead of putting pigments directly into a large amount of resin, a master batch in which pigments are once dispersed at a high concentration is prepared and diluted. The method of throwing in is used. In this case, a solvent is generally used to help dispersibility. However, there is a problem such as the environment, and in this embodiment, water is used for dispersion. When water is used, temperature control is important so that residual moisture in the masterbatch does not become a problem.

Further, a release agent can be internally added to the toner in the present invention to prevent offset at the time of fixing. Release agents include natural waxes such as candelilla wax, carnauba wax and rice wax, montan wax and derivatives thereof, paraffin wax and derivatives thereof, polyolefin wax and derivatives thereof, sazol wax, low molecular weight polyethylene, and low molecular weight polypropylene. And alkyl phosphate esters. The melting point of these release agents is preferably 65 to 90 ° C. When the temperature is lower than this range, blocking during storage of the toner tends to occur, and when the temperature is higher than this range, an offset is likely to occur in a region where the fixing roller temperature is low.

Additives may be added for the purpose of improving the dispersibility of a release agent or the like. Additives include styrene acrylic resin, polyethylene resin, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, butyral resin, terpene resin, There is a polyol resin or the like, and a mixture of two or more of these resins may be used. As the resin, crystalline polyester may be used. It is an aliphatic polyester having crystallinity, having a sharp molecular weight distribution, and increasing the absolute amount of its low molecular weight as much as possible. This resin undergoes a crystal transition at the glass transition temperature (Tg), and at the same time, the melt viscosity suddenly decreases from the solid state and exhibits a fixing function to paper. By using this crystalline polyester resin, low-temperature fixing can be achieved without excessively reducing the Tg and molecular weight of the resin. Therefore, there is no decrease in storage stability associated with a decrease in Tg. Also, there is no excessively high gloss and offset resistance deterioration due to the low molecular weight. Therefore, the introduction of the crystalline polyester resin is very effective for improving the low-temperature fixability of the toner.

The circularity of the toner particles was measured as an average circularity by a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.).

Further, as described above, the toner according to the exemplary embodiment attaches or fixes an inorganic fine powder to the toner surface as a fluidity improver. The average particle size of the inorganic fine powder is suitably 10 to 200 [nm]. When the particle size is smaller than 10 [nm], it is difficult to create an uneven surface having an effect on fluidity, and when the particle size is larger than 200 [nm], the powder shape becomes rough, which is a problem of toner shape. Occurs. As the inorganic fine powder of the present invention, Si, Ti, Al, Mg, Ca, Sr, Ba, In, Ga, Ni, Mn, W, Fe, Co, Zn, Cr, Mo, Cu, Ag, V, Zr, etc. And oxides and composite oxides. Of these, fine particles of silicon dioxide (silica), titanium dioxide (titania), and alumina are preferably used. Furthermore, it is effective to perform a surface modification treatment with a hydrophobizing agent or the like. Typical examples of the hydrophobizing agent include the following. Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, hexaphenyldisilazane, hexatolyldisilazane, etc.

The inorganic fine powder is preferably used in an amount of 0.1 to 3% by weight based on the toner. If the amount is less than 0.1% by weight, the effect of improving toner aggregation is poor. If the amount exceeds 3% by weight, problems such as toner scattering between fine wires, contamination in the machine, scratches and abrasion of the photoreceptor tend to occur. is there. In addition, a charge control agent may be attached or fixed to the surface of at least a powder composed of a resin and a pigment so that the powder surface shape has a small period and a large period. The average particle size is optimally as small as 10 to 200 [nm]. When the particle size is smaller than 10 [nm], it is difficult to create an uneven surface having an effect on fluidity, and when the particle size is larger than 200 [nm], the powder shape becomes rough, which is a problem of toner shape. Occurs.

In addition, the toner of the present exemplary embodiment includes other additives such as a lubricant powder such as Teflon powder, zinc stearate powder, and polyvinylidene fluoride powder within a range that does not substantially adversely affect the toner; or cerium oxide powder, carbonized carbon Abrasives such as silicon powder and strontium titanate powder can also be used in small amounts as developability improvers. In addition, this evaluation method can also be used for toners and capsule toners produced by a spray-drying method produced without using a kneading step or a pulverizing step.

<Second Embodiment>
FIG. 4 is a schematic configuration diagram of a one-component developing device according to the second embodiment. Based on FIG. 4, the structure and operation | movement different from 1st embodiment are demonstrated.

In the developing device 2 shown in FIG. 4, the toner carrying member is composed of a flexible toner carrying belt 11 that moves endlessly, and is stretched around two rollers 12 and 13 so as to move in the counterclockwise direction in FIG. . The toner carrying belt 11 in the vicinity of the lower roller 12 over which the toner carrying belt 11 is stretched is disposed so as to come into contact with the toner in the hopper portion 4 containing the toner. In the hopper portion 4, an agitator 5 having blades around the rotation shaft is disposed so as to stir the toner 7 in the vicinity of the toner carrying belt 11 to be accommodated. By this stirring, the toner 7 in the vicinity of the toner carrying belt 11 is in a state of being unwound even if it is initially in an aggregated state, and the distance between the toners is increased. As a result, the fluidity of the toner 7 in the vicinity of the toner carrying belt 11 is high and the fluidized state is easily moved. The agitator 5 stirs and fluidizes the toner, and is not arranged close to the toner until it is pressed against the toner carrying belt 11.

Further, the toner carrying belt 11 is in contact with the toner in the hopper portion 4 at a portion stretched around the roller 12 to form a toner supply region. In the toner supply area, the toner in the hopper 4 is not pressed against the toner carrying belt 11, and therefore, frictional charging does not occur and the toner is almost uncharged. It adheres to the surface of the toner carrying belt 11. Since the toner in the almost uncharged state does not generate an electrostatic restraining force by the toner carrying belt 11, the adhesion force on the surface of the toner carrying belt 11 and the van der of the toner adhered to the surface of the toner carrying belt 11 and other toners. The toner is carried on the toner carrying belt 11 in a thin layer state by the Waals force.

Further, as shown in FIG. 5, a protrusion 12a is provided on the surface of the lower roller 12 on which the toner carrying belt 11 is stretched. The toner carrying belt 11 is stretched following the projection 12a by the backing of the surface projection 12a of the roller 12 and comes into contact with the toner in the hopper 4 in a state where the surface area is increased, and carries the toner on the surface as described above. . When the surface of the toner carrier belt 11 moves to leave the stretched portion by the roller 12, the surface area returns to the original state, and the adhesion amount substantially increases. As a result, the supply amount to the toner carrying belt 11 can be controlled more. The protrusion 12a has, for example, a diameter of 2 to 3 [mm] and a height of about 0.5 to 1.5 [mm]. This is an example, and the diameter and height of the protrusion 12a can be determined as appropriate.

As the toner carrying belt 11, a belt having flexibility as described above and having a surface coated with a resin of a rubber material is used. As the rubber, rubber materials such as silicon and butadiene corresponding to 20 ° to 30 ° according to JIS A are optimal. In this embodiment, silicon rubber having a thickness of 1.5 mm and JIS A of 25 ° is used. The surface layer was coated with a silicon-based resin with a thickness of 20 [μm].

Further, a charging roller 14 as a toner charging member having a gap with the surface of the toner layer is disposed downstream of the toner supply region and upstream of the development region with respect to the surface movement direction of the toner carrying belt 11. The thin toner layer conveyed to the portion facing the charging roller 14 as the surface of the toner carrying belt 11 moves is charged by being charged by the discharging of the charging roller 13. The charging roller 14 has a metal shaft provided with a conductive layer of conductive metal, resin, or rubber material. The surface of the toner carrying belt 11 is moved by a drive motor (not shown) at a portion facing the toner carrying belt 11. It is driven to rotate in the same direction as the direction. In the present embodiment, the charging roller 14 has a diameter of 15 [mm], and the conductive layer has a thickness of 3.5 [mm]. The gap with the toner carrying belt 11 was set to 50 to 100 [μm]. A high voltage power supply (not shown) (maximum peak-to-peak voltage _VP-P can be output up to about 8 [kV]) is connected to the shaft. The toner was charged by discharging -5 [kV] applied with DC. Further, a toner scraping member 15 is disposed on the surface of the charging roller 13 so that the toner on the toner carrying belt 10 is always charged with a fresh surface so that the toner can be removed immediately even if the toner adheres to the charging roller 14. I try to let them.

<Third embodiment>
FIG. 6 is a schematic configuration diagram of a one-component developing device according to the third embodiment. The developing device according to the third embodiment uses the vibrating member 10 instead of the agitator 5 as the fluidizing means of the toner 7 in the hopper portion 4 in the developing device of the first embodiment. Based on FIG. 6, the configuration and operation different from those of the first embodiment will be described.

In the developing device of FIG. 6, a vibrating member 10 that abuts against the outer wall of the hopper portion 4 is provided. The vibrating member 10 vibrates the toner 7 to be fluidized, and then is carried on the toner carrying sleeve 3. The amplitude of vibration given by the vibration member 10 is a maximum of several millimeters, and a frequency of 100 to 500 [Hz] is effective. However, a frequency that can be adjusted according to the characteristics of the hopper 4 and the toner particle group is preferable. As the vibrating member 10, a piezoelectric element that can apply a voltage, or a member that is attached with an eccentric weight to the driving shaft of a motor and that generates vibration can be used.

In FIG. 6, a motor drive shaft with an eccentric weight is used. Specifically, the vibration member 10 attached to the outer wall of the hopper 4 vibrates at a frequency of 200 [Hz], and the hopper 4 and the internal toner vibrate due to this influence. When the toner particle group vibrates, the toner particle group in an aggregated state is loosened, and the distance between the toners gradually increases and finally fluidizes. The fluidized toner particle group is carried in a thin layer state by being brought into contact with the toner carrying sleeve 3 as in the first embodiment, and is conveyed to the developing region. On the way, when the charger 8 passes, the charge is received from the charger 8 and the toner is charged.

Further, in the present embodiment, a second toner carrying sleeve 9 as a second toner carrying member is provided between the toner carrying sleeve 3 and the photosensitive member 1. Then, a transfer electric field is formed by the power supply 16 so as to transfer the toner from the toner carrying sleeve 3 to the second toner carrying sleeve 9. Thus, by electrostatically transferring the toner, only the sufficiently charged toner on the toner carrier 3 can be transferred to the second toner carrying sleeve 9. Therefore, the toner layer carried on the second toner carrying sleeve 9 is conveyed to the development area with a relatively sharp distribution. The electrostatic latent image formed on the photoreceptor 1 is developed by a developing electric field formed between the second toner carrying sleeve 9 and the photoreceptor 1. Thereafter, an image is formed through a transfer and fixing process.

  The first, second, and third embodiments have been described using the contact development method in which the toner carrier and the latent image carrier are brought into contact with each other, but the toner carrier and the latent image carrier are described. A non-contact development method in which the body is developed in a non-contact manner may be used. In the present embodiment, the best mode for carrying out the present invention has been described. However, it is easy for those skilled in the art to make other embodiments by changing or modifying the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The above description is an example of the best mode of the present invention, and does not limit the scope of the claims.

As described above, in the first, second, and third embodiments, the toner accommodated in the hopper 4 is brought into contact with the toner carrier 3 or 11 without being pressed. Since the toner is not pressed against the toner carriers 3 and 11, it is not charged by friction and is carried in a substantially uncharged thin layer state. Then, the toner is charged without stress from the toner charging members 8 and 14 arranged in a non-contact manner on the surface of the toner layer almost uncharged on the toner carriers 3 and 11. Here, since the toner layer on the toner carriers 3 and 11 is a thin layer, uniform charging can be performed as compared with the case where the toner layer is a thick layer or the toner is a lump. As described above, the toner deterioration over time can be suppressed by stably charging the toner by a method other than frictional charging while suppressing the stress.
Further, by supplying the toner to the toner carrying sleeve 3 in a fluidized state by the fluidizing means 5 and 10, the probability of contact with the surface of the toner carrying sleeve 3 increases. Further, since the relationship of the adhesion force of the toner to the toner carrier> the adhesion force between the toners is established, the toner layer does not become a thick layer, and a thin layer is more easily formed.
In the first and third embodiments, the use of the charger 8 as the toner charging member widens the closest area to the toner layer on the toner carrier and stabilizes the discharge amount. Can be charged easily.
In the second embodiment, by using the charging roller 14 as the toner charging member, the closest distance to the toner layer on the toner carrier can be narrowed, and the discharge amount is set to the minimum necessary. Can do. Therefore, power consumption can be reduced.
In the first and second embodiments, a development electric field is formed between the toner carrier and the photosensitive member 1 in the development region, so that good development can be performed with toner without stress.
In the third embodiment, a second toner carrying sleeve 9 as a second toner carrying member is provided between the toner carrying sleeve 3 and the photosensitive member 1, and the second toner carrying sleeve is formed from the toner carrying sleeve 3. A transfer electric field is formed so as to transfer the toner to 9. Thus, by electrostatically transferring the toner, only the sufficiently charged toner on the toner carrier 3 can be transferred to the second toner carrying sleeve 9. Therefore, the toner layer carried on the second toner carrying sleeve 9 is conveyed to the development area with a relatively sharp distribution, and further good development is performed.
Further, in the first and second embodiments, by using the agitator 5 in the hopper 4 as the toner fluidizing means, the toner can be fluidized by a simple means, and the toner is more evenly distributed on the toner carrier. Can be supplied in a thin layer state.
In the third embodiment, by using the vibrating member 10 as the toner fluidizing means, the toner in the hopper 4 can be fluidized, and the toner can be supplied to the toner carrier in a more uniform thin layer state.
In the second embodiment, the toner carrier is provided with a protrusion 12a on the surface of the roller 12 in the toner supply region where the endlessly moving toner carrier belt 11 having flexibility is stretched. The toner carrying belt 11 is stretched by the backing of the surface protrusion 12a of the roller 12 to carry the toner in a state where the surface area is increased. Then, due to the movement of the surface of the toner carrier belt 11, the surface area returns to the original state, and the amount of adhesion increases substantially. As a result, the supply amount to the toner carrying belt 11 can be controlled more.

1 is a schematic configuration diagram of a developing device according to a first embodiment. 6 is a comparative graph of toner charge amount distribution before and after passing through a toner charging member. The graph which shows the additive embedding rank of the toner of time. FIG. 6 is a schematic configuration diagram of a developing device according to a second embodiment. FIG. 9 is an enlarged view of a toner supply area in the second embodiment. FIG. 9 is a schematic configuration diagram of a developing device according to a third embodiment. 1 is a schematic configuration diagram of a conventional one-component developing device. Explanatory drawing of the toner supply part in the conventional one-component developing device. Explanatory drawing of the toner control part in the conventional one-component developing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing device 3 Toner carrying sleeve 4 Hopper part 5 Agitator 6 Collection roller 7 Toner 8 Toner charging member (charger)
9 Second toner carrying sleeve
DESCRIPTION OF SYMBOLS 10 Vibration member 11 Toner carrying belt 12, 13 Stretching roller 14 Toner charging member (charging roller)
15 scraping member 16 power source 40 toner carrier 41 supply roller 42 regulating blade

Claims (10)

A toner carrier that carries toner contained in the apparatus and conveys the toner to a development area that is opposite to the latent image carrier; and the toner carrier upstream of the development area in the toner conveyance direction of the toner carrier. In a developing device including a toner charging member that charges toner on the body,
The toner contained in the apparatus is brought into contact with a part of the toner carrier without being pressed to carry the toner on the toner carrier, and the toner charging member is attached to the toner on the toner carrier. A developing device, wherein the developing device is arranged with a gap with respect to the surface of the layer.   2. The developing device according to claim 1, further comprising toner fluidizing means for fluidizing the toner accommodated in the apparatus, wherein the toner fluidized by the toner fluidizing means is carried on the toner carrier. apparatus.   3. The developing device according to claim 1, wherein the toner charging member is a dischargeable charger.   3. The developing device according to claim 1, wherein the toner charging member is a dischargeable roller.   5. The developing device according to claim 1, further comprising a developing electric field forming means for forming a developing electric field between the toner carrier and the latent image carrier in the development region. A developing device.   5. The developing device according to claim 1, wherein a second toner carrier disposed between the toner carrier and the latent image carrier, and the toner charge from the toner carrier. A transfer electric field forming means for forming a transfer electric field for transferring the toner charged by the member to the second toner carrier, and development for forming a development electric field between the second toner carrier and the latent image carrier A developing device provided with an electric field forming means.   7. The developing device according to claim 2, wherein the toner fluidizing means is a stirring member disposed in a device for storing toner.   7. The developing device according to claim 2, wherein the toner fluidizing means is a vibrating member that comes into contact with an apparatus housing that contains toner.   9. The developing device according to claim 1, wherein the toner carrier is a flexible endless belt stretched by a plurality of cylindrical members. A developing device characterized in that, among the plurality of cylindrical members, a cylindrical member that stretches the toner carrier at a position in contact with the toner has irregularities on the surface. A latent image carrier that carries an electrostatic latent image, an electrostatic latent image forming unit that forms an electrostatic latent image on the latent image carrier, and a development that develops the electrostatic latent image on the latent image carrier An image forming apparatus comprising:
The developing means includes a toner carrier that carries toner accommodated in the apparatus and conveys the toner to a developing area that is a portion facing the latent image carrier, and a part of the toner carrier includes a toner carrier. The toner carrying member is brought into contact with the toner carrier without being pressed, and the toner is carried on the surface of the toner layer on the toner carrier upstream of the development region in the toner transport direction of the toner carrier. An image forming apparatus comprising: a developing device that charges a toner layer on the toner carrying member with a toner charging member arranged with a gap therebetween.

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