EP0257364A1 - Entwicklungsverfahren für latente elektrostatische Bilder - Google Patents

Entwicklungsverfahren für latente elektrostatische Bilder Download PDF

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Publication number
EP0257364A1
EP0257364A1 EP19870111197 EP87111197A EP0257364A1 EP 0257364 A1 EP0257364 A1 EP 0257364A1 EP 19870111197 EP19870111197 EP 19870111197 EP 87111197 A EP87111197 A EP 87111197A EP 0257364 A1 EP0257364 A1 EP 0257364A1
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EP
European Patent Office
Prior art keywords
resin
toner
carrier
developer
developing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19870111197
Other languages
English (en)
French (fr)
Other versions
EP0257364B2 (de
EP0257364B1 (de
Inventor
Tadashi Konishiroku Photo Ind. Co. Ltd. Kaneko
Yuki Konishiroku Photo Ind. Co. Ltd. Okuyama
Mitsutaka Konishiroku Photo Ind. Co. Ltd. Arai
Yoko Konishiroku Photo Ind. Co. Ltd. Yamamoto
Satoru Konishiroku Photo Ind. Co. Ltd. Ikeuchi
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Konica Minolta Inc
Original Assignee
Konica Minolta Inc
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Priority claimed from JP61183422A external-priority patent/JPS6340170A/ja
Priority claimed from JP61183423A external-priority patent/JPS6340171A/ja
Application filed by Konica Minolta Inc filed Critical Konica Minolta Inc
Publication of EP0257364A1 publication Critical patent/EP0257364A1/de
Application granted granted Critical
Publication of EP0257364B1 publication Critical patent/EP0257364B1/de
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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/06—Developing
    • G03G13/08—Developing using a solid developer, e.g. powder developer
    • G03G13/09—Developing using a solid developer, e.g. powder developer using magnetic brush
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
    • G03G9/1132—Macromolecular components of coatings
    • G03G9/1133—Macromolecular components of coatings obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/1134—Macromolecular components of coatings obtained by reactions only involving carbon-to-carbon unsaturated bonds containing fluorine atoms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
    • G03G9/1132—Macromolecular components of coatings
    • G03G9/1135—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/1136—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon atoms

Definitions

  • This invention relates to a developing method for elec­trostatic latent images and, more particularly, to a develop­ing method for electrostatic latent images formed on a latent image carrying member in electrophotography, electrostatic recording, electrostatic printing and the like by making use of a two-component type developer.
  • the methods for forming a visible image from an image information the methods such as electrophoto­graphy, electrostatic recording and electroprinting are widely utilized, in which visible images are formed through electro­static latent images.
  • developer used for developing the above-mentioned electrostatic latent images: one is the so-­called two-component type developer comprising toners and car­riers in the form of mixture and the other is a single compo­nent type developer comprising magnetic toners containing mag­ netic substances, which is used independently without mixing with carriers.
  • toners are frictionally charged by mechanically stirring the toners and carriers.
  • the above-mentioned non-contact devel­oping system is a system in which a developer layer comprising toners and carriers, which is carried on a developer trans­port/carrying member, is fed into a developing area so as not to bring the developer layer into direct contact with the latent image carrying member.
  • toners and carriers may hardly be frictionally charged, because the fluidity of the carriers is liable to be lowered as they are getting smaller in size.
  • the electrostatic and physical bonding strength of the carriers to a developer transport/carrying member is weakened and, similarly, the elctrostatic and physi­cal bonding strength of the carriers to the toner is also weakened.
  • the carriers are usually transported by magnetic force with being adhered to the surface of the developer transport/carrying member though, in the case of using small-­sized carriers, the adhesion force of the carriers to the de­veloper transport/carrying member is weak.
  • the carriers or toners will fly about in an apparatus to contaminate the in­side thereof, and the toners or carriers will adhere to the non-image areas of the latent image carrying member to produce fog; and, further, the carriers will adhere to the latent image carrying member to make an image unclear.
  • a thin developer layer may hardly be formed on the developer transport/carrying member and the de­veloper layer is liable to be uneven in thickness and, result­ingly, the undesirable phenomena such as uneven imaging and imaging failure are taken place in a fixed image ultimately obtained, so that no sharp image may finally be obtained.
  • Fog will be produced by the weakly charged toners; the toners will fly about; the carriers to which toner substances adhere will adhere to an electrostatic latent image so as to lower the image quality; the carriers will adhere to the elec­trostatic latent image so as to lower the image quality; a statisfactorily thin layer will hardly be formed on the devel­oper/transport carrying member; and the like problems, so that no sharp image will finally be obtained.
  • a minimum gap that is a development gap, between a latent image carrying member and a developer transport/carrying member in a developing area.
  • a developability may be improved by generating a rela­tively greater oscillatory electric field in a development area as well as by making a development gap larger though, in the case of generating such a greater oscillatory electric field as the development gap is made wider, there is such a problem that toners will adhere increasingly to the non-image portions of a latent image carrying member to produce fog and carriers will increasingly fly about to contaminate the inside of an apparatus. Further, it is necessary to insulate a de­veloping unit satisfactorily from electricity and the design­ing of the units is considerably complicated, because of the generation of the greater oscillatory electric field.
  • This invention is based on the circumstances mentioned above.
  • an object of the invention ro provide a developing method in which no contamination is caused inside an apparatus by flying both toners and carriers about, no fog is produced, an excellent development can be performed with a two-component type developer comprising the toner and carriers and, resultingly, a sharp image can be formed so as to be ex­cellent in both resolving power and gradation reproduction.
  • Another object of the invention is to provide a develop­ing method capable of forming a sharp image without having any uneven imaging and imaging failure.
  • a further object of the invention is to provide a devel­oping method in which a thin developer layer can stably be formed on a developer transport/carrying member even in re­peating development processes many times and, resultingly, excellent images can stably be formed, extending over a long period of time.
  • the developing method of the invention is a developing method in which a two-component type developer layer compris­ing toners and carriers is formed on a developer transport/­carrying member and the resulted developer layer is fed into a developing area where an oscillatory electric field is gen­erated so as to develop an electrostatic latent image on a latent image carrying member; and is particularly character­ized in thinning the developer layer formed on the developer transport/carrying member and in using resin coated carriers comprising the particles of magnetic substances coated with the resins containing silicone resin or fluororesin in an amount of at least 30% by weight or more, for serving as the above-mentioned carriers.
  • the carrier surfaces are smoothed out, because the carriers form­ing two-component type developer are the resin-coated carriers comprising magnetic particles coated with a resin containing a silicone resin having a low surface energy as its property.
  • the so-called tonre filming phenomenon that is a phenomenon that toner sub­stances adhere to carrier surfaces to hinder the frictional chargeability of the carriers, in a frictional charge between toners and carriers. Therefore, the toners may be endowed stably with a frictional charge having proper polarity and charged volume.
  • the carriers forming a two-component type developer are resin-coated carriers comprising magnetic particles coated with resins containing fluororesing in an amount of not less than a specific proportion
  • the carrier surfaces are smoothed out, because a fluororesin is low in critical surface tension as its property.
  • toner filming phenomenon that is a phenomenon that toner substances includ­ing, for example, coloring agents such as Carbon Black and so forth, surface releasing agents, etc., adhere to carrier sur­faces to hinder the frictional changeability of the carriers, in a frictional charge between toners and carriers.
  • the toners may be endowed stably with a frictionally charge having proper polarity and charged amount.
  • the order of frictional chargeability of a fluororesin is the most negative among resins and, accordingly, the carriers coated with resins containing the fluororesin are also excel­lent in negative chargeability. Therefore, in the toners used with the carriers in combination, it is not particularly re­quired to use any charge controller or fine grained additive such as dyes so as to provide the toners with a positive chargeability. Resultingly, the troubles caused when using the charge controllers and the like may be prevented. Be­sides, the frictional chargeability of toners may be control­led to a considerable degree by selecting a fluororesin con­tent in the resins for coating carriers. It is, therefore, possible to prepare developers suitable for the developing method of the invention.
  • the surface releasing property of the car­riers becomes excellent, because the carrier surface is smoothed.
  • a thin developer layer is formed, for example, by bringing a thin layer forming member such as a blade into pressure contact elastically with a developer transport/carry­ing member, it is possible to prevent carriers from adhering to the thin layer forming member so as to prevent the thick­ness regulating function of the thin layer forming member from being interfered by the carrier adhesion.
  • the de­veloper transport/carrying member is received a strong pres­sure by the thin layer forming member, it is possible to pre­vent carriers from adhering physically and strongly to toners. Therefore, a thin developer layer may stably be formed on the developer transport/carrying member.
  • a developer layer having a two-compo­nent type developer comprising toners and carriers is formed on a developer transport/carrying member.
  • the developer layer is supplied to a developing area where an oscillatory electric field is generated and an electrostatic latent image on a latent image carrying member is developed.
  • the developer layer formed on the developer transport/carrying member is thinned and a resin­coated carrier comprising magnetic particles coated with a resin containing a silione resin is used for the carriers.
  • a developer layer on a developer transport/carrying member is thinned.
  • the thickness of the thin layer is preferably not more than 2,000 ⁇ m, more preferably not more than 1,000 ⁇ m and particularly from 10 to 500 ⁇ m.
  • a dvelopment process is carried out in such a manner that a developer layer, which is considerably thinned as mentioned above, is transported into a developing area where an oscil­latory electric field is generated so as to bring the developer layer into contact or, preferably, non-contact with a latent image carrying member and the oscillatory electric field is applied to the developer layer.
  • a minimum gap between the latent image carrying member and the developer transport/carrying member (hereinafter called a "development gap”) is desired to be as narrow as possible, provided that the developer layer may be transported into the developing area so that the developer layer may not come into contact with the latent image carrying member.
  • the development gap is preferably selected from the range of gap of from 100 to 1,000 ⁇ m, for example.
  • a developing area means an area to which toners transported by a developer transport/­carrying member may be able to transfer when an electrostatic latent image on a latent image carrying member receives an electrostatic force.
  • a development gap means a closest space be­tween a latent image carrying member and a developer trans­port/carrying member in the above-defined developing area.
  • the carriers used in the invention area resin-coated car­ riers comprising magnetic particles coated with a resin con­taining a silicone resin or a fluororesin in a proportion of not less than 30% by weight.
  • the thickness of the coated layer is preferably from 0.1 to 10 ⁇ m on average, more preferably from 0.3 to 4 ⁇ m and particularly from 0.3 to 2 ⁇ m.
  • the resin may be comprised of either only a silicone resin or both of the silicone resin and a highly compatible resin used in combination for more improv­ing the properties of the silicone resin.
  • the developer trans­port/carrying members for transporting a thin developer layer to a developing area.
  • the developer transport/carrying members having the same construction as in the conventional types which are capable of applying a bias voltage, may also be used.
  • a developer layer carried on the surface of the developing sleeve is transported in undulations like waves by the rotation of the magnetic roll.
  • a developer layer formed on a developer transport/carrying member is thinned.
  • the non-contact and contact development systems may be used either.
  • the non-contact development system is preferably used.
  • the reasons are that a development gap may satisfactorily be narrowed, because a developer layer formed on a developer transport/carrying mem­ber is thinned as mentioned before so as to lower a bias volt­age required for generating an oscillatory electric field by which toners are properly flown from the developer transport/­carrying member to the latent image carrying member in a non-­ contact developing area, and that there are also the advant­ages of reducing undesirable toner flying about and preventing the bias voltage from leaking out of the developing speeve surface, because a satisfactory oscillatory electric field may be generated by the relatively low bias voltage.
  • toners are present in a proportion of the order of at least 0.04 mg/cm2 in a developer layer car­ried on a developing sleeve.
  • V s (mm/s) represents a linear velocity of a developing sleeve
  • V d (mm/s) represents a linear velocity of a latent image carrying member
  • m t (mg/cm2) represents an amount of toners per unit area of a developer layer carried on the developing sleeve:
  • the toners con­tained in a developer layer carried ona developing sleeve may be made efficiently adhere to an electrostatic latent image formed on a latent image carrying member and a stable develop­ment may be made and, resultingly, it is possible to reproduce images having extraordinarily excellent image qualities.
  • the means for forming such a thin developing layer as mentioned before on a develop­ing sleeve there is no special limitation to the means for forming such a thin developing layer as mentioned before on a develop­ing sleeve, and the means having a variety of constitutions may be used.
  • the examples thereof in­clude a means in which the thickness of a developer layer are regulated by bringing a thin layer forming member such as a blade into pressure contact elastically with the surface of a developing sleeve and, preferably, a means in which the thick­nesses of a developer layer are regulated by arranging a re­gulating plate made of a magnetic substance and a developing sleeve so as to keep a specific gap between them, that is, for example, a means in which the thicknesses of a developer layer are regulated by arranging a magnetic bar close to a develop­ing sleeve and then by generating a rotating magnetic field on the magnetic bar, or other means having been well-known.
  • a thin layer forming member haivng a pressure plate brought into pressure contact lightly and elastically with a developing sleeve.
  • the edge of the elastic pressure plate is brought into the developing sleeve toward the upper stream side of the rotation of the developing sleeve.
  • a thin developer layer may be formed by passing a developer through the gap between this elastic pressure plate and the developing sleeve.
  • Fig. 4 is a diagram illustrating the relation of a gap between the edge of an elastic pressure plate and a developing sleeve (The gap sizes are inproportion to aperture areas) to a quantity per unit area of a developer carried on the develop­ing sleeve, in the case of using the above-mentioned elastic pressure plate.
  • a quantity per unit area of a developer carried on a developing sleeve shows a stable value regardless of the sizes of a gap, when the gap between the edge of an elastic plate and the developing sleeve exceeds a specific size.
  • toners sufficient for developing an electrostatic latent image may be transport­ed into a developing area.
  • a gap between the edge of the elastic plate and the developing sleeve that is, a gap of not wider than 5 mm. If exceeding 5 mm, there is some fear of making the thickness of a developing layer uneven.
  • Fig. 1 is an illustration showing an example of a devel­oping unit suitable for performing the developing method of the invention.
  • reference numeral 20 is a latent image carry­ing member of, for example, a rotary drum type; 2 is a hous­ing; 3 is a developing sleeve; 4 is a magnetic roll having a magnetic polarity of eight-pole type in total arranged N and S poles alternately around the circumference of the roll; and a developer transport/carrying member is comprised of the devel­oping sleeve 3 and the magnetic roll 4.
  • 5 is a thin layer forming member
  • 6 is a member for fixing thin layer forming member 5
  • 7 is a pri­ mary stirring member
  • 8 is a secondary stirring member
  • 9 and 10 are the shaft for rotating the above-mentioned stirring members 7 and 8, respectively
  • 11 is a vessel of replenishing toners
  • 12 is a roller of replenishing toners
  • 13 is a devel­oper reservoir
  • 14 is a bias power source
  • 15 is a developing area
  • T is a toner
  • D is a developer.
  • developer D is well stirred and mixed up in developer reservoir 13 by both of pri­mary stirring member 7 rotating in the direction of the arrow and secondary stirring member 8 rotating in the direction op­posite to the rotation of primary stirring member 7 so as to overlap the stirring areas of the both stirring members with­out colliding against each other and the developer D is then made adhere to the surface of developing sleeve 3 by the transportation force produced by both of developing sleeve 3 rotating in the direction of the arrow and magnetic roll 4 rotating in the direction opposite to the rotation of the de­veloping sleeve 3.
  • Plate-like thin layer forming member 5 comprising an elastic material brings one side of the plate close to the edge into pressure contact with the surface of developing sleeve 3.
  • This thin layer forming member 5 is held by fixing member 6 extended from housing 2.
  • fixing member 6 extended from housing 2.
  • the developer layer thinned in this manner is transported into developing area 15 as the layer is facing to an electro­static latent image formed on latent image carrying member 20 rotating in the direction of the arrow, preferably through a narrow gap, so to say, so as not to come into contact with each other.
  • the thin devel­oper layer is being subjected to the oscillatory electric field generated by bias power source 14 containing a.c. com­ponents, only the toners held in the developer layer selec­tively and statically adhere to the electrostatic latent image, so that a toner image is formed.
  • a thickness of a developer layer may be measured in the following manner, for example. With a "Nikon Profile Projec­tor" (manufactured by Nippon Kogaku Co.), the position of the image of a developing sleeve projected on a screen and the position of the image of athin developer layer formed on the developing sleeve projected on the screen are compared with each other to obtain the thickness of the developer layer.
  • Thin layer forming member 5 may be made of, for example, a magnetic or non-magnetic metal, a metal compound, a plastic, rubber and so forth. This member 5 is endowed with elasticity by fixing one end of the member 5 with fixing member 6. It is preferable that the thickness of this member 5 is very thin and uniform in thickness, that is from 50 to 500 ⁇ m.
  • An amount of carrier transported is regulated in such a manner that the above-mentioned thin layer forming member 5 brings one side close to the edge thereof into contact elas­tically with developing sleeve 3 and, preferably, the carriers may be passed one after anothre through the contact position of the thin layer forming member 5 with developing sleeve 3.
  • the impurities remaining in developer D, aggregates of car­riers or toners and so forth are prevented from stealing into developing area 15 by the thin layer forming member 5. There­fore, every developer layer transported into developing area 15 becomes thin, uniform and stable in thickness.
  • the developing method of the invention there uses a resin-coated carrier which is coated with a resin containing a silicone resin or a resin containing a fluororesin in a specific proportion or more. Therefore, the surface of the carrier is excellently smoothed even if the carrier is small-­sized, because of the coated layer. The fluidity of the car­rier is thereby improved. Accordingly, the thickness regulat­ing function of the thin layer forming member 5 is satisfac­torily displayed and, resultingly, every developer layer transported into developing area 15 may be satisfactorily uni­formed and thinned in thickness. Further, the surface lubri­city of the carrier is also excellent because of the coated layer. Therefore, the so-called filming phenomenon, that is, an adhesion of toner substances to carriers, may be prevented, even if the developer layer is applied with a strong pressure by thin layer forming member 5.
  • An amount of developer transported into developing area 15 may satisfactorily be controlled by changing the pressure and contact angles applied from thin layer forming member 5 to developing sleeve 3.
  • toners and carriers forming a developer it is gen strictlyerally advantageous that they are small-sized, because an image obtainable is high in resolving power and excellent in gradation reproduction.
  • a two-component type developer comprising toners having a weight average particle size of not larger than 5 ⁇ m and carriers having a weight average particle size of not larger than 50 ⁇ m and further not larger than 30 ⁇ m, any impurities, particle aggregates and so forth may automatically be removed from the developer so as to form a uniformed and thinned de­veloper layer.
  • any impurities may be prohibited from stealing into the resulting developer layer by thin layer forming member 5 similar to the above-mentioned example, so that a uniformed and thinned developed layer may be formed.
  • a carrier having a weight average particle size of the order of from 50 to 100 ⁇ m it is advantageous to use a carrier having a weight average particle size of the order of from 50 to 100 ⁇ m.
  • a satisfactorily uniform and thin developer layer may be formed by thin layer forming member 5 and a carrier may also satisfactorily be prevented from adhering to latent image carrying member 20.
  • brush-like ears i.e., a magnetic brush
  • the carriers held in a developer layer are heightened and the layer is made coarse, so that hte developability is lowered.
  • a magnetization of the carriers is preferably from 10 to 200 emu/g, more preferably from 10 to 100 emu/g and, particularly from 15 to 30 emu/g. If the magnetization of the carriers is too little, there may be some instance where none of excellent magnetic bruches may be formed. If the magnetization is too great, there may be some instances where an oscillatory electric field may not function well, so that an excellent image may hardly be formed.
  • Figs. 2(a) and 2(b) are a perspective view and a front view each for illustrating an example of the detailed unit structure of stirring members 7 and 8.
  • 7a, 7b and 7c are stirring blades of primary stirring member 7 and 8a, 8b and 8c are the stirring blades of secondary stirring member 8, respectively.
  • These stirring blades are arranged at an angle and/or position different from each other blades and fixed to rotating shafts 9 and 10, re­spectively.
  • These stirring members 7 and 8 are so arranged as to overlap each other member in a stirring area without col­liding each othre blades. In Fig. 1, therefore, a stirring may satisfactorily be performed in the direction of the right to left.
  • each stirring blade is slanted to the corresponding rotating shaft and fixed.
  • a stirring may also satisfactorily be performed in the direction of back and forth. Accordingly, toners T are re­plenished from toner replenishing vessel 11 through replenish­ing roller 12 so that they are uniformly mixed up with devel­oper D within a short time.
  • Toners and carriers are frictionally charged well by the above-mentioned stirring members 7 and 8 and the resulting developers are allowed to adhere to and held on developing sleeve 3 by magnetic force and a thin developer layer is then formed by thin layre forming member 5.
  • the thin developer layer While being transported toward a specific direction by the rotation of the developing sleeve 3, the thin developer layer receives a magnetic bias having a oscillatory component and derived from the reverse rotation of the magnetic roll 4 and performs unique, such as rolling, on the developing sleeve 3. Accordingly, the toner particles satisfactorily adheres to an electrostatic latent image formed on the latent image car­rying member 20 especially if the thin developer layer trans­ported to the developing area receives the influence of the oscillatory electric field on a non-contact basis in relation to the electrostatic latent image.
  • the thickness of developer layer is favorably set extremely small, or more specifically, at 10 to 500 ⁇ m.
  • This arrangement enables to narrow the de­velopment gap between the latent image carrying member 20 and the developing sleeve, for example, to 500 ⁇ m, and according­ly, ensures development in compliance with the so-called non-­contact developing system.
  • Such a narrower development gap enhances the electric field strength in the developing area 15. This in turn en­ables satisfactory development operation even if the bias voltage applied onto the developing sleeve 3 is smaller, and, advantageously, reduces the leakage of bias voltage, and other disadvantages. Furthermore, the resultant greater contrast in the elevtrostatic latent image generally improves the resolu­ tion and quality of an image obtainable from the development operation.
  • the developing method of the in­vention may be favorably used for the multicolor development system in which the development process is repeatedly effected on an latent image carrying member where a toner image is formed.
  • the developer used in embodying the invention is a two-­component developer comprising a toner, as well as a resin-­coated carrier composed of magnetic particles each of which being coated with resin involving silicone resin or fluoro­resin resin in an amount of at least 30 weights.
  • a toner comprises fine particles each composed of binder resin containing a toner component such as a coloring agent.
  • the preferred binder resins used for toner include poly­ester resin, styrene-acryl resin, and the like.
  • the polyester resin favorably used as the binder resin of toner is prepared by the condensation polymerization of al­cohol monomer and carboxylic monomer.
  • al­cohol monomer and carboxylic monomer examples include as follows: diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl gly­col, 1,4-butenediol and the like; etherified bisphenols such as 1,4-bis(hydroxymethyl) cyclohexane, bisphenol A, hydro­genated bisphenol A, polyoxyethylene bisphenol A, polyoxypro­pylene bisphenol A and the like; other bivalent alcohol mono­mers.
  • exmaples of such a bivalent carboxylic monomer are as follows; maleic acid, fumaric acid, methaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, isophthalic acid, cyclohexanedi­carboxylic acid, succinic acid, adipic acid, sebatic acid, malonic acid; anhydrides, lower alkyl esters, and linolenic dimers of these acids; other bivalent organic acid monomera.
  • polyester resin favorably used as the binder resins of toner
  • polymers having multifunctional monomeric compo­nents, larger than trifunctional ones are also favorably used in addition to the polymers comprising the above bifunctional monomers.
  • the examples of multivalent alcohol monomers, or the above multifunctional monomers, whose valence being larger than trivalence, are as follows: sorbitol, 1,2,3,6-hexane­tetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, saccharose, 1,2,4-butanetriol, 1,2,5-­pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-­butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-­trihydroxymethylbenzene, and the like.
  • multivalent carboxylic monomers whose valence being larger than trivalence, are as follows: 1,2,4-­benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetri­carboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-­butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-­dicarboxyl-2-methyl-2-methylenecarboxylpropane, tetra (methylenecarboxy)methan, 1,2,7,8-octanetetracarboxylic acid, empoltrimer acid; anhydrides of these acids; and others.
  • the resins not only having an Mw/Mn ratio, which is a ratio between weight-average molecular-weight Mw and number-average mole­cular-weight Mn, of mor than 3.5 but containing ⁇ , ⁇ -unsatu­rated ethylene monomer, which was disclosed for example in Japanese Patent O.P.I. Publication No. 134652/1975, as a com­ponent are favorably used.
  • ⁇ , ⁇ -­unsaturated ethylene monomer are as follows: aromatic vinyl monomers such as styrene, o-methylstyrene, p-methylstyrene, ⁇ -­ methylstyrene, p-ethylstyrene, 2,4-dimethylstryrene, p-n-­butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-­oxtylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecyl­styrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like; acrylic esters such as
  • the values of number-average molecular-weight Mn and weight-average molecular-weight Mw in a specific polymer may be measured by various methods. Though the measured results differ depending upon a measuring method, the number-average molecular-weight Mn as well as the weight-average molecular-­weight Mw in this specification are defined as the values de­termined by the following method.
  • each of these values is a value deter­mined by a gel permeation chromatography with the following conditions; a solvent (tetrahydrofuran) is allowed to flow at a rate of 1.2 ml per minute with a temperature of 40°C, where­by 3 mg tetrahydrofuran solution of a density 0.2 g/20 ml con­taining a sample is added for the measuring operation.
  • measuring condi­tions are selected so that the counted number of the molecular weight of the sample provides a linear relation with the logarithmic numbers on the analitical curve formed from the measuring results with various types of monodispersion poly­styrene reference samples.
  • any columns may be used as for as they satisfy the above conditions. More spec­ifically, a TSK_GE, GMH (manufactured by Toyo Soda Mfg. Co., Ltd.) or the like may be used.
  • a preferred binder resin used for toner has a softening point Tsp of 80 to 150°C, or, more specifically, 100 to 140°C.
  • a glass transition point Tg of the similar resin is favorably 40 to 80°C, or in particular, 50 to 70°C.
  • the softening point Tsp refers to a temperature determined in the following manner: using a flow tester Model CFT-500 manufactured by Shimazu Seisakusho Ltd., the measurement was recorded with measuring conditions of 20 kg/cm2 load, 1 mm nozzle diameter, 1 mm noz­zle length, 80°C pre-heating for 10 minutes, 6°C/min heating rate, and 1 cm3 (weight represented by intrinsic specific gravity ⁇ 1 cm3), wherein, by assuming the height of S curve in the characteristic curve (softening fluidization curve) re­presenting the correlation between the amount of plunger drop in the flow tester and the corresponding temperature is h, the softening point is determined by reading a temperature corre­sponding to h/2.
  • the glass transition point is a value determined in the following manner: using a differential scanning calorimeter Model Low-temperature DSC manufactured by Rigaku Denkisha Co., Ltd., a measuring operation is performed at a heating rate of 10°C/min, whereby the glass transition point is read from the temperature on an intersection, in a DSC thermogram, between the extension of baseline below the glass transition point and the tangent line representing a maximum slope from the initial rising portion to summit of a peak.
  • the toner used in the invention comprises binder resin particles containing a coloring agent, as well as other toner component added in compliance with a requirement.
  • the examples of useful coloring agent are as follows: Carbon Black, Nigrosine Dye (C.I. No. 50415B), Aniline Blue (C.I. No. 50405), Chalcoil Blue (C.I. No. Azoic Blue 3), Chrome Yellow (C.I. No. 14090), Ultramarine Blue (C.I. No. 77103), DuPont Oil Red (C.I. No. 26105), Quinoline Yellow (C.I. No. 47005), Methylene Blue Chloride (C.I. No. 52015), Phthalocyanine Blue (C.I. No. 74160), Malachite Green Oxalate (C.I. No. 42000), Lamp Black (C.I. No. 77266), Rose Bengal (C.I. No. 45435), and mixtures involving any of the above agents, and others.
  • various surface releasing agents are favorably incorporated into the toner.
  • Such a useful surface releasing agent in­clude polyolefin, metal salt of aliphatic acid, aliphatic ester, partially saponified aliphatic ester, higher alcohol, fluid or solid paraffin wax, amide wax, multivalent alcohol ester, silicone varnish, aliphatic fluoro carbon, and the like.
  • those preferred have a softening point, measured by a ring and ball test specified in JIS K2531-1960, of 80 to 180°C, in particular 70 to 160°C.
  • These surface releasing agents may be singly used, or more than two of them may be combinedly used.
  • the examples of above-mentioned useful polyolefin include resins such as polypropylene, polyethylene, polybutene and the like.
  • the examples of above-mentioned metal salt of aliphatic acid are as follows: salts of maleic acid and a metal such as zinc, magnesium, calcium and the like; salts of stearic acid and a metal such as zinc, cadmium, barium, lead, iron nickel, cobalt, copper aluminum, magnesium, and the like: lead salt of dibasic stearic acid; salts of oleinic acid and a metal such as zinc, magnetisum, iron, cobalt, copper, lead, calcium and the like; salts of palmitic acid and a metal such as aluminum, calcium and the like; lead caprate, lead capronate, metal salts of linoleic acid and a metal such as zinc, cobalt and the like; salts of ricinoleic acid and a metal such as zinc, cadmium and the like; and the mixture of these salts.
  • the examples of the above-mentioned useful aliphatic ester include ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, ethylene glycol montanate and the like.
  • apliphatic ester for example, a montanic ester whose calcium area is saponified may be used.
  • the examples of the above-mentioned useful higher alipha­tic acid include dodecanic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linolic acid, ricino­leic acid, arachic acid, behenic acid, lignoceric acid, cera­choleic acid and the like, and a mixture of these acids.
  • the examples of the above-mentioned useful higher alcohol include dodecyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, aralkyl alcohol, behenyl alcohol and the like.
  • the examples of the above-mentioned useful paraffin wax include natural paraffin, microcrylstalline wax, synthetic paraffin, chlorinated hydrocarbon and the like.
  • amide stearate amide stearate
  • amide oleinate amide palmitate
  • amide laurate amide behenate
  • methylenebisstearoamide ethylene­bisstearoamide and the like.
  • the examples of the above-mentioned useful alcohol ester include glycerol stearate, glycerol ricinolate, glycerol mono­behenate, sorbitan monostearate, propylene glycol monostea­rate, sorbitan triolate and the like.
  • the examples of the above-mentioned useful silicone var­ nish include methylsilicone varnish, phenylsilicone varnish and the like.
  • the examples of the above-mentioned useful aliphatic fluoro carbon include lower polymers such as ethylene tetra­fluoride and propylene hexafluoride, and a fluorine-containing surface active agent disclosed in Japanese Patent O.P.I. Pub­lication No. 124428/1978, and other agents.
  • the proportion of these surface release agents to be used is favorably 1 to 10 part weight per 100 parts weight binder resin.
  • toner components are as follows: fluidizing agents such as fine silica powder, fine titania powder, fine alumina powder and the like; abrasive powder such as cerium oxide; lubricants such as zinc stearate and the like; charge controlling agents such as pigment or dye; and others.
  • the preferred toner used in the invention has a weight-­average particle size of less than 20 ⁇ m, in particular, 1 to 15 ⁇ m.
  • the use of a toner having such a preferred weight-­average particle size enables an image having extremely good image quality to be formed.
  • the use of a toner having an excessively large weight-average particle size readily decreases the image resolution and may sometimes de­crease the gradation reproducibility.
  • the use of a toner having an excessively small weight-average par­ticle size may cause the toner to fly around in an image form­ ing apparatus, and this in turn may sometimes decrease the sharpness of resultant image.
  • a carrier composing a two-­component developer together with a toner is, as mentioned previously, a resin-coated carrier whose individual particles comprise a magnetic particle coated with a resin containing silicone resin or fluororesin in an amount of at least 30 weights thereof.
  • condensation-reaction type silicone resins the particularly favorable ones are those having a methyl sub­stituent.
  • the coating layer com­posed of a methyl-substituted condensation-reaction type sili­cone resin provides a carrier having a satisfactory water-­repelling property and excellent moisture-resistance.
  • a silicone resin used to form the coating layer of carrier particle whichever a thermosetting silicone resin or normal-temperature setting silicone resin may be used. Since a high temperature not being necessary to set a resin, the used of normal-temperature setting silicone resin simplifys the carrier preparation.
  • the normal-temperature setting silicone resin is a sili­cone resin which hardens, under a normal atmosphere, at a tem­perature of 20 to 25°C, or a little higher, and accordingly, does not require a temperature exeeding 100°C.
  • the silicone resin used as the coating layer of carrier is prepared by singly or combinedly using the above-described silicone resins, or a resin having not only the above silicone resin but another resin may be used for this purpose.
  • Such another resin is favorably one having a high compartibility with a silicone resin.
  • the exmaples of such a resin include an acryl resin, styrene resin, epoxy resin, urethane resin, polyamide resin, polyester resin, acetal resin, polycarbonate resin, phenol resin, vinyl chloride resin, vinyl acetate resin, cellulose resin, polyolefin resin, copolymers of these resins, blend resins of these resins, and others.
  • fluororesins used for forming the coating layer of carrier is not specifically limited, however, the preferred fluororesin is one capable of being dissolved in solvent, and being applied onto the surface of magnetic parti­cle by a conventional coating method.
  • the fluororesin used to form the coating layer of carrier is prepared by singly or combinedly using the above-described fluororesin, or a resin having not only the above fluororesin but another resin may be used for this purpose.
  • a resin having not only the above fluororesin but another resin may be used for this purpose.
  • Such another resin is favorably one having a high compatibility with a fluororesin.
  • the examples of such a resin include an acryl resin, styrene resin, epoxy resin, urethane resin, polyamide resin, polyester resin, acetal resin, polycarbonate resin, phenol resin, vinyl chloride resin, vinyl acetate resin, cel­lulose resin, polyolefin resin, copolymers of these resins, blend results of these resins, and others.
  • the conente of fluororesin in the coating resin is at least 30 weight%, or more favorably, 40 to 100 weight%, or most favorably 50 to 100 weight%. Less than 30 weight% of fluororesin content does not fully provide the favorable pro­perty of fluororesin, often resulting in unstable triboelec­tric charging characteristic.
  • the magnetic particle serving as a core being coated with a resin is a particle made of a substance which is strongly magnetized in the direction of magnetic field.
  • a substance which is strongly magnetized in the direction of magnetic field.
  • the examples of such a substance are as follows: metals showing ferromagnetism such as ferrite, magnetite, as well as iron, nickel, cobalt and the like; alloys or compounds involving these metals; alloy not having ferromagnetic element but being endowed with ferromag­netism by an appropriate heat-treatment, and being typified by Heusler alloys such as manganese-copper-aluminum alloy, man­ganese-copper-tin, and the like; chromium dioxide and the like.
  • ferrite is a general term of a magnetic oxide involving iron and is not limited only to a Spinel structure ferrite represented by a formula MO.Fe2O3 (M represents a bivalent metal atom).
  • MO.Fe2O3 M represents a bivalent metal atom.
  • a ferrite is especially advant­ageous to prepare a carrier which best suits the object of the invention.
  • a ferrite powder has a specific gravity much smaller than metal powder such as iron powder or nickel powder.
  • This feature allows easy mixing and blending with a toner, and advantageously con­tributes to the uniformity of toner concentration in the de­veloper as well as to the optimization of triboelectrical potential formed in toner powder.
  • a further advantage is that, since having a resistivity of 108 to 1012 ⁇ .cm, which is greater than that of iron powder, nickel powder or cobalt powder, the ferrite powder provides an insulative carrier satisfactorily used in a developing method in which a high bias voltage is applied to the developing gap, even when the layer thickness of resin forming the surface of carrier parti­ cle is extremely small, approximately 0.5 ⁇ m.
  • the above-mentioned ferrite favorably has a saturated magnetiza­tion of 10 to 40 emu/g and a coercive force of 0.1 to 100 Oe. Furthermore, the ferrite favorably has a resistivity of 1 ⁇ 106 to 1 ⁇ 1011 ⁇ .cm, a specific gravity of 4.0 to 5.5, and a porosity of 1.0 to 10%.
  • the coating layer is formed in the following steps.
  • a solution prepared by dis­solving silicone resin or fluororesin, and, if necessary, an­other resin, in a solvent is applied on the surface of indi­vidual magnetic particles by a dipping method, spray method, fluidized bed method or the like, whereby usually by heating, the solvent is allowed to vaporize and the solution is allowed to dry, then during or after the drying, the coat layer is allowed to set.
  • a solvent being used for this purpose is not specifically lim­ited, as far as a silicone resin, fluororesin, and another additional resin can be dissolved in such a solvent.
  • the typical examples of such a solvent are as follows: aro­matic hydrocarbons such as toluene, xylene and the like; ketones such as acetone, methylethyl ketone; tetrahydrofuran; dioxane; higher alcohol; and mixed solvents involving any of the above solvents.
  • thermosetting sili­cone resin requires heating at 200 to 250°C.
  • a normal-­temperature setting silicone resin does not require heating with a high temperature
  • the heating with a temperature range of 150 to 250°C may be performed to accelerate the setting.
  • a metal soap of octyl acid, nephthic acid or the like and lead, iron, cobalt, tin, manganese, zinc or the like may be used as a dryer.
  • an organic amine such as ethanol amine may be satisfactorily used as a dryer.
  • the preferred thickness of the formed resin coating-layer containing silicone resin is usually 0.1 to 20 ⁇ m.
  • the preferred heating temperature necessary for setting a coating layer comprising a resin containing fluororesin is usually 100 to 350°C.
  • a dryer or setter composed of, for example, an organic metal salt such as zinc octylate, dibutyl zinc oxide or the like may be used.
  • the preferred thickness of the formed resin coating-layer containing fluororesin is, for example, 0.1 to 10 ⁇ m, and more specifically, 0.3 to 4 ⁇ m, and most specifically, 0.3 to 2 ⁇ m.
  • the individual particles of resin-coated carrier used in the invention are favorably spherical-shaped and have a weight-average particle size of less than 100 ⁇ m, and more favorably, 5 to 50 ⁇ m.
  • the use of a resin-coated carrier hav­ing such a favorable weight-average particle size improves the image resolution as well as the gradation reproducibility.
  • the use of a carrier having an excessively large weight-­average particle size may sometimes make it difficult to form a thin developer layer on a developer bearing/carrying member, and possibly resulting in the deteriorated developability and decreased image quality.
  • the used of a carrier having an excessively small weight-average particle size may sometimes deteriorate the developability, triboelectrical charging property, fluidity and the like, and may cause the carrier to fly around in an image forming apparatus.
  • a resin-coated carrier used in the invention is an insu­lative carrier having a registivity of more than 108 ⁇ .cm, favorably, more than 1013 ⁇ .cm, and more favorably, more than 1014 ⁇ .cm.
  • the use of such a highly insulative carrier satis­factorily prevents, in the course of developing, a potential from being injected by a bias voltage and resulting in a film­ing of carrier on the surface of a latent image carrying mem­ber, or a potential to form an electrostatic latent image from being eliminated.
  • the weight-average particle sizes of toner and carrier are values determined with a Coulter Counter manu­factured by Coulter Ltd.
  • the resistivities of magnetic particles as well as resin-­ coated carrier particles are determined by the following proc­edure: sample particles are poured into a container having a cross-sectional area of 0.50 cm2 and tamped down, then a load of 1 kg/cm2 is applied onto the tamped sample particles so as to make the thickness of sample to be approximately 1 mm, whereby an electrical field of 102 to 105 V/cm is applied to between the load and a bottom electrode and the value of cur­rent flowing is measured.
  • the preferred blending ratio between toner and car­rier is a ratio where the total surface area of toner is ap­proximately same as the similar area of carrier. For example, if a weight-average particle size of toner is 10 ⁇ m and a weight-average particle size of carrier is 20 ⁇ m, the prefer­red toner concentration (weight ratio per total developer) is 5 to 40 weight%, in particular, 8 to 25 weight%.
  • Fig. 3 is an explanatory diagram schematically illustrativelying one example of image forming apparatus being used in em­bodying the developing method of the invention.
  • the move of a draft table causes the optical draft image formed by an illuminating light source 21 to be focused on a latent image carrying member 20 via a mirror 22 and a lens 23, and an elec­trostatic latent image corresponding to an original draft is formed on the latent image carrying member 20.
  • a developing unit A has a constitution, for exmaple, shown in Fig. 1.
  • the electrostatic latent image formed on the latent image carrying member is developed by the developing unit A to form a toner image.
  • a toner image obtained in such a manner is transferred onto a recording paper P with a transfer electrode 29 after being electrically neutralized for easy transfer by an expo­sure lamp 28.
  • the recording paper P is separated by a separa­tion electrode from the latent image carrying member 20 and is fixed with a fixer 31 to form a fixed image.
  • the latent image carrying member 20 is electrically neutralized by a neutralization electrode 32 and its surface is cleaned by a cleaning mechanism 33.
  • the cleaning mechanism 35 in this example has a cleaning blade 34 for scraping off toner. Toner particles scraped off by the blade 34 are collected by a roller 36.
  • spherical copper-zinc ferrite particles having a weight-average particle size of 35 ⁇ m 100 parts spherical copper-zinc ferrite particles having a weight-average particle size of 35 ⁇ m (manufactured by TDK Corporation) were coated with 25 parts condensation-reaction type silicone resin solu­tion SR-2411 (manufactured by Toray Silicone Co., Ltd.) at a temperature of 80°C, and were further heat-treated at a tem­perature of 200°C for one hour to obtain a carrier having in­dividual particles being coated with a silicone resin layer.
  • the coating layer has a thickness of approximately 1 ⁇ m.
  • the carrier was designated carrier A.
  • the properties of the carrier A were as follows: Weight average particle size 42 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity more than 1014 ⁇ .cm Specific gravity 4.9 g/cm3
  • a carrier having particles individually being coated with a 1 ⁇ m thick silicone resin layer was prepared in a manner identical to that of carrier A except that silicone resin solution SR-2410 was used in the place of silicone resin solu­tion SR-2411. This carrier was designated carrier B.
  • the properties of the carrier B were as follows: Weight-average particle size 35 ⁇ m Magnetization 16 emu/g (Measured magnetic feild: 1000 Oe) Resistivity 1014 ⁇ .cm Specific gravity 4.8 g/cm3
  • a carrier having aprticles individually being coated with a 1 ⁇ m thick silicone resin layer was prepared in a manner identical to that of carrier A except that thermosetting sili­cone resin solution (manufactured by The Sin-Etsu Chemical Co., Ltd.) was used in the place of silicone resin solution SR-2411. This carrier was designated carrier C.
  • the properties of the carrier C were as follows: Weight average particle size 42 ⁇ m Magnetization 14 emu/g (Measured magnetic field: 1000 Oe) Resistivity more than 1014 ⁇ .cm Specific gravity 4.8 g/cm3
  • a carrier comprising copper-zinc ferrite particles iden­tical to those of carrier A was designated comparison carrier a.
  • the properties of the comparison carrier a were as fol­lows: Weight-average particle size 40 ⁇ m Magnetization 18 emu/g (Measured magnetic field: 1000 Oe) Resistivity 4 ⁇ 1010 ⁇ .cm Specific gravity 5.2 g/cm3
  • a carrier having particles individually have a coating layer of 1 ⁇ n thick styrene was prepared in a manner identical to that of carrier A except that toluene solution (solid con­tent, 10 weight%) containing styrene resin (weight-average molecular weight Mw, 71,000; number-average molecular weight Mn, 32,000; glass transition point Tg, 125°C) was used in the place of silicone resin solution SR-2411.
  • This carrier was designated comparison carrier b.
  • the properties of the comparison carrier b were as fol­ lows: Magnetism 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity more than 1014 ⁇ .cm Specific gravity 4.9 g/cm3
  • a carrier having particles individually being coated with a 1.5 ⁇ m thick methyl methacrylate resin layer was prepared in a manner identical to that of carrier A except that toluene solution (solid content, 10 weight%) containing methyl metha­crylate resin (weight average molecular Mw, 73,000; number average molecular Mn, 33,000; glass transition point Tg:-121°C) was used in the place of silicone resin solution SR-2411.
  • This carrier was designated comparison carrier c.
  • the properties of the comparison carrier c were as fol­lows: Weight-average particle size 40 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity more than 1014 ⁇ .cm Specific gravity 4.8 g/cm32
  • black toner A To 100 aprts weight of the black toner powder, 0.5 parts weight hydrophobic fine silica particles (R-812, manufactured by Nippon Aerozyl Co., Ltd.) was added, then thoroughly blend­ed by a Henschel mixer to prepare black toner. This toner was designated black toner A.
  • the static bulk density of the black toner A was 0.44 g/cm3.
  • a yellow toner was prepared in a manner identical to that of black tonre A except that yellow pigment, Pigment Yellow, was used in the place of Carbon Black. This toner was desig­nated yellow toner B. The static bulk density of the yellow toner B was 0.44 g/cm3.
  • magenta tonre was prepared in a manner identical to that of black tonr A except that magenta pigment, Permanent Carmine F-5B, was used in the place of Carbon Black. This toner was designated magenta toner C.
  • the static bulk density of the magenta toner C was 0.45 g/cm3.
  • a cyan toner was prepared in a manner identical to that of black tonre A except that cyan pigment, Copper Phthalo­cyanine, was used in the place of Carbon Black. This toner was designated cyan toner D.
  • the static bulk density of the cyan toner D was 0.44 g/cm3.
  • the above-mentioned carriers A through C were independ­ently combined with the black tonre A to prepaer developers 1 through 3 individually having a toner concentration of 10 weight%.
  • the above-mentioned comparison carriers a through c were also combined with the black toner A to correspondingly prepare comparison developer 1 through 3 individually having a toner concentration of 10 weight%.
  • yellow toner B, magenta toner C and cyan toner D were independently combined with carrier A to corre­spondingly prepare color developers 1 through 3 individually having a toner concentration of 12 weight%.
  • Latent image carrying member 100 mm dia.
  • drum type photosensitive member made of selenium - Linear velocity: 100 mm/sec - Surface potential: +800 V (image area) to +50 V (non-­image area) -
  • Diameter of developing sleeve 25 mm - Linear velocity of developing sleeve: 250 mm/s (for­ward direction) -
  • Total number of poles on magnetic roll 8 poles
  • Rotational speed of magnetic roll 1200 rpm
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the sur­face of developing sleeve -
  • Development gap 500 ⁇ m - Thickness of developer layer: 400 ⁇ m (maximum value) -
  • Toner content in developer 10 weight% - Toner content in developer layer formed on developing sleeve: 0.3 mg/cm2 -
  • DC bias voltage 50 to 200 V -
  • AC bias voltage 1.0 to 2 kV
  • a fixed image was inspected with human eye.
  • the surface of latent image carrying/transporting member was inspected with human eye.
  • a fixed image was inspected with human eye.
  • the developing method of the invention using any of the devel­opers 1 through 3 provides a sharp image, whose quality is comparable to that of the first copied image, even after 30000 sheet-copying operation. Additionally, inspection of the con­tamination in an image forming apparatus confirmed only an ex­tremely limited contamination with toner and carrier. This is because the silicone resin to form the coating layer of the carrier used in embodying the invention has a smaller critical surface tension when compared to a resin used to prepare a comparison carrier, and accordingly, the toner substance does not easily adhere to the surface of individual carrier parti­cles. Furthermore, the developing effects of bias voltage was satisfactorily demonstrated.
  • the sue of comparison developer 1 incurred a smaller triboelectricity even in the initial stage of continu­ous 30000 sheet copying operation, and an obtained image was not sharp, showing considerable fog, imaging failure and un­even imaging. Also, the carrier adhesion on the latent image carrying member was found. In addition, the above problems further deteriorated after the completion of 30000-sheet copy­ing operation, because of furthre decreased toner triboelec­tricity. Also, considerable adhesion of toner material on the surface of individual carrier particles also occurred.
  • comparison developer 2 incurred a smaller triboelectricity even in the initial stage of continu­ous 30000-sheet copying operation, and an obtained image was not sharp, showing minor fog, imaging failure and uneven imag­ing.
  • the above problems further deteriorated after the completion of 30000-sheet copying operation, because of further decreased toner triboelectricity. Also, consider­able adhesion of toner material on the surface of individual carrier particles also occurred.
  • comparison developer 3 incurred imaging fail­ure and uneven imaging on an obtained image during the initial stage of continuous 30000-sheet copying operation, and the carrier adhesion on the latent image carrying member was also found. After the completion of 30000-sheet copying operation, the toner triboelectricity further decreased, and accordingly, the obtained image is not sharp, showing minor fog, as well as imaging failure and uneven imageing. Also, considerable car­rier adhesion on the latent image carrying member as well as considerable adhesion of tonre substance on the surface of in­dividual carrier particles also occurred.
  • test was performed in a manner identical to the above test 1 by actual copying operation except that the modified developing conditions below were used. The results similar to those of test 1 were obtained.
  • Latent image carrying member 140 mm dia.
  • drum type photosensitive member having organic photocon­ductive photosensitive layer - Linear velocity: 60 mm/sec - Surface potential: -700 V (image area) to -50 V (non- image area) - Diameter of developing sleeve: 20 mm - Linear velocity of developing sleeve: 250 mm/s (for­ward direction) - Total number of poles on magnetic roll: 8 poles - Rotational speed of magnetic roll: 1000 rpm - Thin layer forming member: 3 mm thick resilient plate made or urethane rubber, being pressed on the sur­face of developing sleeve - Development gap: 500 ⁇ m - Thickness of developer layer: 400 ⁇ m (maximum value) - Toner content in developer: 10 weight% - Toner content in developer layer formed on developing sleeve: 0.4 mg/cm2 - DC bias voltage: -500 to -600 V - AC bias voltage: 1.0 to 2.5
  • FIG. 5 schematically illustrates the constitution of an­other example of an image forming apparatus used in embodying the developing method of the invention, wherein an image input unit IN is unit-built and comprises an illuminating light source 1, a mirror 22, a lens 23 and one-dimensional color CCD image sensor 24.
  • the image input unit IN is shifted in the direction shown by an arrox x with an unshown driving mecha­nism, and the CCD image sensor 24 reads an original draft.
  • a draft table may be shifted to shift the original draft 25.
  • the image information read by the image input unit IN is converted into data suitable for recording at an image proc­essing unit TR.
  • a laser optical system 26 forms a latent image on the image carrying member 20 in the following manner and based on the above-mentioned image data.
  • the surface of image carrying member 20 is uniformly electrified with a Scorotron electrification electrode 27.
  • image exposure light L with the recorded data incorporate is illuminated from the laser optical system 26 via a lens upon the image forming member 20. In this way, an electrostatic latent image corre­sponding to the original draft is formed on the latent image carrying member 20.
  • the electrostatic latent image is developed by a develop­ing unit A containing yellow toner B.
  • the latent image carry­ing member 20 on which a toner image has been formed in again uniformly electrified by the Scorotron electrification elec­trode 27 and receives image exposure light L into which re­corded data of anothre color element has been incorporated.
  • the formed electrostatic latent image is developed by a devel­oping unit B containing magenta toner C.
  • a two-color toner image of yellow toner B and magenta toner C is formed on the image carrying member 20.
  • a cyan toner D image as well as a black toner A image are consecutively superposed on the two-color toner image to form a four-color toner image on the latent image carrying member 20.
  • the developing units A, B, C, and D respectively containing each color toner commonly have the constitution similar to that of the developing unit in Fig. 1.
  • a multicolor toner image obtained in such a manner is transferred on a recording paper P with a transfer electrode 29 after being electrically neutralized for eash transfer by an exposure lamp 28.
  • the recording paper P is separated by a separation electrode 30 from the latent image carrying member 20 and is fixed with a fixer 31, thus forming a fixed image.
  • the triboelectricity on the image carrying member 20 is neutralized by a neutralization electrode 32, and the surface of which is cleaned by a cleaning mechanism 33.
  • the cleaning mechanism 33 in this example has a cleaning blade 34 and a fur brush 35 which are kept out of contact with the latent image carrying member 20 during formation of an image. Once a multicolor image is finally formed on the latent image carrying member 20, the cleaning blade 34 and the fur brush 35 come in contact with the latent image carrying member 20 and scrape off toner left untransferred on the mem­ber 20. Then, the cleaning blade 34 leaves the latent image carrying member 20, and, a little later, the fur brush also leaves the latent image carrying member.
  • the fur brush 35 functions to remove toner left on the latente image carrying member 20 after the cleaning blade 34 leaves the member 20.
  • Numeral 36 denotes a roller which collects toner scraped off by the blade 34.
  • FIG. 9 A typical example of laser optical system 26 is shown in Fig. 9.
  • numeral 37 denotes a semiconductor laser generator
  • numeral 38 a rotatable polygon mirror
  • numeral 39 a f ⁇ lens.
  • Fig. 6 schematically illustrates the change in the sur­face potential of latent image carrying member having a posi­tive triboelectrically polarity.
  • PH represents an exposure area in the latent image carrying member
  • DA a non-exposure area in the similar member
  • DUP an increase in potential due to the adhesion of positive-charged toner T ⁇ on the expo­sure area PH caused by the first development.
  • the latent image carrying member is uniformly electrified with a Scorotron electrode, so as to have a specific positive surface potential E as shown in Fig. 6-(1).
  • the first imagewise exposure is effected by an exposure light source such as a laser, cathode ray tune, LED or the like, whereby the potential of exposure are PH drops in proportion to the light amount as shown in Fig. 6-(2).
  • An electrostatic latent image formed in this way is developed by a developing unit to which a positive bias voltage approximately equal to the sur­face potential E on the non-exposure area is applied.
  • a positive-charged toner T adheres to the exposure area PH having a relatively low potential as shown Fig. 6-(3), thus the first toner image is formed.
  • a multicolor toner image is formed on the latent image carrying member. Then, the multicolor toner image is trans­ferred onto a recording paper, which is heated or pressed to fix the image. Thus, the multicolor recorded image is finally formed. Toner and triboelectrical potential on the surface of latent image carrying member are removed, and the next se­quence of multicolor image forming is prepared. Additionally, it is also possible to use a method to fix a multicolor toner image directly onto the latent image carrying member. In the developing method illustrated in Fig. 6, it is favorable that the processing step in Fig. 6-(6) be performed without allow­ing the developer layer to come in contact with the surface of latent image carrying member.
  • Latent image carrying member 140 mm dia.
  • drum type photosensitive member having organic photocon­ductive photosensitive layer - Linear velocity: 60 mm/sec - Surface potential: -700 V (non-image area) to -50 V (image area)
  • Exposure light source Semiconductor laser (wave­length, 780 nm; recording den­sity, 16 dots/mm) - Constitution of developing units A through D
  • Diameter of developing sleeve 20 mm
  • Linear velocity of developing sleeve 250 mm/s (for­ward direction)
  • Total number of poles on magnetic roll 8 poles
  • Rotational speed of magnetic roll 800 rpm
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the surface of developing sleeve
  • Development gap 0.4 mm
  • Maximum magnetic flux density on surface of develop­ing sleeve 700 gauss
  • Thickness of developer layer 250 ⁇ m (maximum value)
  • Developing sleeve may be electrically floated.) - Developing sequence: (Yellow) ⁇ (Magenta) ⁇ (Cyan) ⁇ (Black) - Transfer process: Corona discharge method - Fixing process: Heat roll method - Cleaning process: Blade and fur brush
  • the toner when executing the developing method of the invention, demonstrated a proper triboelectricity, and a sharp color image featuring high-resolution as well as excellent gradation reproducibility is formed without accompanying any of fog, carrier adhesion of the image carrying member, imaging failure, and uneven imaging.
  • the developing method of the invention is capable of pro­viding a sharp image, whose quality is comparable to that of the first copied image, even after 30000 sheet-copying opera­tion. Additionally, inspection of the contamination in an image forming apparatus confirmed only an extremely limited contamination with toner and carrier.
  • FIG. 8 schematically illustrate the outline of another example of image forming apparatus used for embodying the de­veloping method of the invention.
  • This image forming appara­tus has a constitution, wherein a multicolor toner image is formed at once, while a latent image carrying members com­pletes one rotation.
  • the image forming apparatus in Fig. 8 differs from the apparatus in Fig. 5 in that:
  • the image When forming, for example, a four-color image with this image forming apparatus, and even if the linear velocity of the latent image carrying member is set equal to that of the apparatus in Fig. 5, the image may be formed approximately four times swiftly than the latter apparatus.
  • a test operation to form 30000 sheets of copied image was performed so as to examine, respectively in the initial stage of image forming operation and after the completion of 30000-sheet copying operation, the triboelectricity on toner, fog, adhe­sion of carrier on a latent image carrying member, imaging failure, and uneven imaging.
  • the results were as satisfactory as those of the previously mentioned test 3 by actual copying operation.
  • Latent image carrying member 140 mm dia.
  • drum type photosensitive member having organic photocon­ductive photosensitive layer - Linear velocity: 200 mm/sec - Surface potential: -700 V (non-image area) to -50 V (image area) -
  • Exposure light source Semiconductor laser (wavelength, 780 nm; recording density, 16 dots/mm) - Constitution of developing units A through D
  • Diameter of developing sleeve 20 mm
  • Linear velocity of developing sleeve 500 mm/s (for­ward direction)
  • Total number of poles on magnetic roll 8 poles
  • Rotational speed of magnetic roll 1500 rpm
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the surface of developing sleeve Development gap: 0.3 ⁇ m
  • Maximum magnetic flux density on surface of develop­ing sleeve 700 gauss
  • Thickness of developer layer 250 ⁇ m (maximum value)
  • Developing sleeve may be electrically floated.) - Developing sequence: (Yellow) ⁇ (Magenta) ⁇ (Cyan) ⁇ (Black) - Transfer process: Corona discharge method - Fixing process: Heat roll method - Cleaning process: Blade system
  • the color development sequence may be modified; for example, (black) ⁇ (yellow) ⁇ (magenta) ⁇ (cyan).
  • the coating solution was applied to copper-zinc ferrite particles (particle size distribution, 15 to 60 ⁇ m; weight-average particle size, 35 ⁇ m), whereby heating with 100°C temperature was performed to prepared carrier having in­dividual particles being coated with resin containing fluoro­resin.
  • the thickness of coating layer was 1.0 ⁇ m. This car­rier was designated carrier X.
  • the properties of the carrier X were as follows: Weight-average particle size 35 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1014 ⁇ .cm
  • a carrier having particles individually being coated with a 1.0 ⁇ m thick fluororesin layer was prepared in a manner identical to that of carrier X except that a polymer compris­ing monomer represented by the following general formula was used instead of the vinylidene fluoride-tetrafluoro ethylene copolymer.
  • the properties of the carrier Y were as follows: Weight-average particle size 40 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1014 ⁇ .cm
  • This carrier was designated carrier Z.
  • the properties of the carrier Z are as follows: Weight-average particle size 40 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1014 ⁇ .cm
  • a carrier comprising copper-zinc ferrite particles iden­tical to those of carrier X was prepared. This was designated comparison carrier x.
  • the properties of the comparison carrier x were as fol­lows: Weight-average particle size 38 ⁇ m Magnetization 22 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1010 ⁇ .cm
  • a carrier having particles individually have a coating layer of 1.0 ⁇ m thick styrene resin was prepared in a manner identical to that of carrier X except that styrene (weight-­average molecular weight Mw, 71,000; number-average molecular weight Mn, 32,000; glass transition point Tg, 125°C) was used instead of vinylidene fluoride-tetarfluoro ethylene copolymer.
  • This carrier was designated comparison carrier y.
  • the properties of the comparison carrier y were as fol­lows: Weight-average particle size 30 ⁇ m Magnetization 20 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1014 ⁇ .cm
  • a carrier having particles individually have a coating layer of 1.0 ⁇ m thick styrene resin was prepared in a manner identical to that of carrier X except that methyl methacrylate resin (weight-average molecular weight Mw, 73,000; number-­average molecular weight Mn, 33,000; glass transition point Tg, 121°C) was used instead of vinylidene fluoride-tetrafluoro ethylene copolymer.
  • This carrier was designated comparison carrier z.
  • the properties of the comparison carrier z were as fol­lows: Weight-average particle size 40 ⁇ m Magnetization 18 emu/g (Measured magnetic field: 1000 Oe) Resistivity More than 1014 ⁇ .cm
  • black toner O To 100 parts weight of the black toner powder, 0.6 parts weight hydrophobic fine titania particles (T-805, manufactured by Nippon Aerozyl Co., Ltd.) was added, then thoroughly blend­ed by a Henschel mixer to prepare black toner. This toner was designated black toner O.
  • the static bulk density of the black toner O was 0.38 g/cm3.
  • a yellow tonre having a weight-average particle size of 11 ⁇ m was prepared in a manner identical to that of black toner O except that yellow pigment, Pigment Yellow, was used in the place of Carbon Black. This toner was designated yel­low toner P. The static bulk density of the yellow toner P was 0.28 g/cm3.
  • magenta toner having a weight-average particle size of 11 ⁇ m was prepared in a manner identical to that of black toner O except that magenta pigment, Permanent Carmine F-5B, was used in the place of Carbon Black. This toner was desig­nated magenta toner Q. The static bulk density of the magenta toner Q was 0.29 g/cm3.
  • a cyan toner having a weight-average particle size of 11 ⁇ m was prepared in a manner identical to that of black toner O except that cyan pigment, Pigment Blue 1, was used in the place of Carbon Black. This toner was designated cyan toner R.
  • the static bulk density of the cyan toner was 0.27 g/cm3.
  • the above-mentioned carriers X through Z were indepdend­ently combined with the black toner O to prepare developers 4 through 6 individually having a toner concentration of 12 weight%.
  • the above-mentioned comparison carriers x through z were also combined with the black toner O to correspondingly prepare comparison developer 4 through 6 individually having a toner concentration of 12 weight%.
  • yellow toner P, magenta toner Q and cyan toner R were independently combined with carrier X to corre­spondingly prepare color developers 4 through 6 individually having a toner concentration of 12 weight%.
  • Latent image carrying member 100 mm dia.
  • drum type photosensitive member made of selenium - Linear velocity: 100 mm/sec - Surface potential: +800 V (non-iamge area) to 0 V (image area) -
  • Diameter of developing sleeve 25 mm - Linear velocity of developing sleeve: 25 mm/s (forward direction) -
  • Total number of poles on magnetic roll 8 poles
  • Rotational speed of magnetic roll 1200 rpm
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the sur­face of developing sleeve -
  • Development gap 500 ⁇ m - Thickness of developer layer: 400 ⁇ m (maximum value) - Toner content in developer: 12 weight% - Toner content in developer layer formed on developing sleeve: 0.3 mg/cm2 -
  • DC bias voltage 600 to 700 V -
  • AC bias voltage 0.5 to 2 kV (frequency
  • the developing method of the invention using any of the devel­opers 4 through 6 provides a sharp image, whose quality is comparable to that of the first copied image, even after 30000 sheet-copying operation. Additionally, inspection of the con­tamination in an image forming apparatus confirmed only an ex­tremely limited contamination with toner and carrier. This is because the fluororesin to form the coating layer of the car­rier used in embodying the invention has a smaller critical surface tension when compared to a resin used to prepare a comparison carrier, and accordingly, the toner substance does not easily adhere to the surface of individual carrier parti­cles. Furthermore, the developing effects of bias voltage was satisfactorily demonstrated.
  • comparison developer 4 incurred a smaller triboelectricity even in the initial stage of continu­ ous 30000-sheet copying operation, and an obtained image was not sharp, showing fog, and uneven imaging.
  • the above problems further deteriorated after the completion of 30000-sheet copying operation, because of further decreased toner triboelectricity.
  • considerable carrier adhesion on the latent image carrying member, as well as imaging fail­ure were also found.
  • comparison developer 5 provided a relatively smaller triboelectricity even in the initial stage of continuous 30000-sheet copying operation, and an obtained image was not sharp, showing imaging failure and uneven imag­ing.
  • the above problems further deteriorated after the completion of 30000-sheet copying operation, because of further decreased toner triboelectricity.
  • large fog ocurred, and minor carrier adhesion on the latent image car­rying member was also found.
  • comparison developer 6 incurred imaging fail­ure and uneven imaging on an obtained image during the initial stage of continuous 30000-sheet copying operation, and the carrier adhesion on the latent image carrying member was also found. After the completion of 30000-sheet copying operation, the toner triboelectricity significantly decreased, and ac­cordingly, the obtained image is not sharp, showing great fog, as well as imaging failure and uneven imaging. Also, minor carrier adhesion on the latent image carrying member also occurred.
  • test was performed in a manner identical to the above test 5 by actual copying operation except that the modified developing conditions below were used. The results similar to those of test 5 were attained.
  • Latent image carrying member 140 mm dia.
  • drum type photosensitive member having organic photocon­ductive photosensitive layer - Linear velocity: 60 mm/sec - Surface potential: -700 V (image area) to -50 V (non-­image area) - Diameter of developing sleeve: 20 mm - Linear velocity of developing sleeve: 250 mm/s (for­ward direction) - Total number of poles on magnetic roll: 8 poles - Rotational speed of magnetic roll: 1000 rpm - Thin layer forming member: 0.1 mm thick resilient plate made of phosphor bronze plate being pressed on the surface of develop­ing sleeve - Development gap: 500 ⁇ m - Thickness of developer layer: 400 ⁇ m (maximum value) - Toner content in developer: 12 weight% - Toner content in developer layer formed on developing sleeve: 0.4 mg/cm2 - DC bias voltage: -100 to -200 V - AC bias voltage: 0.5 to
  • Example 2 Using the image forming apparatus illustrated in Fig. 5 and already described in Example 2, a test operation to form 30000 sheets of copied image was performed, in a manner iden­tical to that of test 3 by actual copying operation, so as to examine, respectively in the initial stage of image forming operation and after the completion of 30000-sheet copying ope­ration, the triboelectricity on toner, fog, adhesion of car­rier on a latent image carrying member, imaging failure, and uneven imaging. The results are listed in Table 4 shown later.
  • Latent image carrying member 140 mm dia.
  • drum type photosnsitive member having selenium-tellu­rium photosensitive layer - Linear velocity: 60 mm/sec - Surface potential: +700 V (non-image area) to + 50 V (image area)
  • Exposure light source Semiconductor laser (wavelength, 780 nm; recording density, 16 dots/mm) - Constitution of developing units A through D
  • Diameter of developing sleeve 20 mm
  • Linear velocity of developing sleeve 250 mm/s (for­ward direction)
  • Total number of poles on magnetic roll 8 poles
  • Rotational speed of magnetic roll 800 rpm
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the surface of developing sleeve
  • Development gap 0.3 mm
  • Maximum magnetic flux density on surface of develop­ing sleeve 700 gauss
  • Thickness of developer layer 250 ⁇ m (maximum value)
  • Developing sleeve may be electrically floated.) - Developing sequence: (Yellow) ⁇ (Magenta) ⁇ (Cyan) ⁇ (Black) - Transfer process: Corona discharge method - Fixing process: Heat roll method - Cleaning process: Blade system and fur brush
  • the toner demonstrated a proper triboelectricity, and a sharp color image featuring high-resolution as well as excellent gradation reproducibility is formed without accompanying any of fog, carrier adhesion of the image carrying member, imaging failure, and uneven imaging.
  • the developing method of the invention is capable of pro­viding a sharp image, whose quality is comparable to that of the first copied image, even after 30000 sheet-copying opera­tion. Additionally, inspection of the contamination in an image forming apparatus confirmed only an extremely limited contamination with toner and carrier.
  • a test operation to form 30000 sheets of copied image was performed, in a manner iden­tical to that of test 3 by actual copying operation, so as to examine, respectively in the initial stage of image forming operation and after the completion of 30000-sheet copying ope­ration, the triboelectricity on toner, fog, adhesion of car­rier on a latent image carrying member, imaging failure, and uneven imaging.
  • the results were as satisfactory as those of the previously mentioned test 7 by actual copying operation.
  • Latent image carrying member 140 mm dia.
  • drum type photosensitive member having As2Se2 photosen­sitive layer - Linear velocity: 200 mm/sec - Surface potential: +700 V (non-image area) to +50 V (image area)
  • Exposure light source Helium-neon laser (wavelength, 632.8 mm; recording density, 16 dots/mm)
  • Constitution of developing units A through D Diameter of developing sleeve: 20 mm Linear velocity of developing sleeve: 50 mm/s (for­ward direction) Total number of poles on magnetic roll: 8 poles
  • Rotational speed of magnetic roll 1500 rp m
  • Thin layer forming member 3 mm thick resilient plate made of urethane rubber, being pressed on the surface of developing sleeve
  • Development gap 500 ⁇ m
  • Maximum magnetic flux density on surface of develop­ment sleeve 700 gauss
  • Thickness of developer layer 400 ⁇ m (maximum value)
  • Developing sleeve may be electrically floated.) - Developing sequence: (Yellow) ⁇ (Magenta) ⁇ (Cyan) ⁇ (Black) - Transfer process: Corona discharge method - Fixing process: Heat roll method - Cleaning process: Blade system
  • the color development sequence may be modified; for example, (black) ⁇ (yellow) ⁇ (magenta) ⁇ (cyan).
  • the developing method of the invention may be advantageously applied also to an apparatus being capable of forming a multicolor toner image with one imagewise exposure on a latent image carrying member.
  • a multicolor toner image is formed, for example, in the following manner.
  • the latent image carrying member is triboelectri­cally cahrged to smooth its potential pattern, and subjected to a specific color light different from the above-mentioned specific color light, so as to form a potential pattern on the filter layer of the latent image carrying member, whereby the potential pattern is developed by a developing unit containing a specific color toner different from the above-mentioned specific color.
  • This procedure forms the second color toner iamge as superposed on the first color toner image already formed on the latent image carrying member. Additionally, in performing this type of developing process, at least the sec­ond developing onwards should be effected in compliance with non-contact developing method.
  • Such a type of multicolor image corming apparatus com severelypletes a multicolor image forming with only one sequence of the imagewise exposure, and this in turn precludes the possi­bility of an image whose independent toner images are not mis­aligned to each other.
  • the latent image carrying member may either have a con­stitution (refer to Japanese Patent Application No. 199547/­1984), wherein a filter is incorporated into the electrocon­ductive substrate side, so as to perform the imagewise expo­sure as well as uniform exposing on the filter side, or an­other constitution (refer to Japanese Patent Application No. 201084/1984).
  • a photosensitive may either be made of a single layer or have a function-separating constitution com­prising both a charge generating layer and a charge transport­ing layer (refer to Japanese Patent Application No. 245178/­1985).
  • a latent image carrying member may have a constitution, wherein the photosensitive layer has color se­paration function (refer to Japanese Patent Applications Nos. 201085/1984 and 245177/1985).

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Dry Development In Electrophotography (AREA)
EP19870111197 1986-08-06 1987-08-03 Entwicklungsverfahren für latente elektrostatische Bilder Expired - Lifetime EP0257364B2 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP61183422A JPS6340170A (ja) 1986-08-06 1986-08-06 静電潜像の現像方法
JP61183423A JPS6340171A (ja) 1986-08-06 1986-08-06 静電潜像の現像方法
JP183422/86 1986-08-06
JP183423/86 1986-08-06

Publications (3)

Publication Number Publication Date
EP0257364A1 true EP0257364A1 (de) 1988-03-02
EP0257364B1 EP0257364B1 (de) 1992-10-21
EP0257364B2 EP0257364B2 (de) 1997-10-15

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2628540A1 (fr) * 1988-03-08 1989-09-15 Canon Kk Procede de formation d'images developpateur et toner utilises dans ce procede
EP0363900A2 (de) * 1988-10-13 1990-04-18 Daikin Industries, Limited Träger für die Entwicklung elektrostatischer Bilder
CN112789526A (zh) * 2018-10-05 2021-05-11 Jsr株式会社 光学传感器用组合物

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3004152A1 (de) * 1979-02-07 1980-09-04 Mita Industrial Co Ltd Magnetischer entwickler und verfahren zu dessen herstellung
DE3511171A1 (de) * 1984-03-27 1985-10-03 Ricoh Co., Ltd., Tokio/Tokyo Traegerteilchen fuer einen zweikomponenten-trockenentwickler
EP0161128A1 (de) * 1984-03-23 1985-11-13 EASTMAN KODAK COMPANY (a New Jersey corporation) Trockene elektrostatische Zweikomponentenentwickler-Zusammensetzung
EP0188171A1 (de) * 1984-12-25 1986-07-23 Kanto Denka Kogyo Co., Ltd. Träger zur Verwendung in elektrophotographischen Entwicklern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3004152A1 (de) * 1979-02-07 1980-09-04 Mita Industrial Co Ltd Magnetischer entwickler und verfahren zu dessen herstellung
EP0161128A1 (de) * 1984-03-23 1985-11-13 EASTMAN KODAK COMPANY (a New Jersey corporation) Trockene elektrostatische Zweikomponentenentwickler-Zusammensetzung
DE3511171A1 (de) * 1984-03-27 1985-10-03 Ricoh Co., Ltd., Tokio/Tokyo Traegerteilchen fuer einen zweikomponenten-trockenentwickler
EP0188171A1 (de) * 1984-12-25 1986-07-23 Kanto Denka Kogyo Co., Ltd. Träger zur Verwendung in elektrophotographischen Entwicklern

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2628540A1 (fr) * 1988-03-08 1989-09-15 Canon Kk Procede de formation d'images developpateur et toner utilises dans ce procede
EP0334099A2 (de) * 1988-03-08 1989-09-27 Canon Kabushiki Kaisha Bilderzeugungsverfahren
EP0334099A3 (de) * 1988-03-08 1991-08-07 Canon Kabushiki Kaisha Bilderzeugungsverfahren
EP0363900A2 (de) * 1988-10-13 1990-04-18 Daikin Industries, Limited Träger für die Entwicklung elektrostatischer Bilder
EP0363900A3 (en) * 1988-10-13 1990-06-27 Daikin Industries, Limited Carriers for developing electrostatic images
CN112789526A (zh) * 2018-10-05 2021-05-11 Jsr株式会社 光学传感器用组合物
CN112789526B (zh) * 2018-10-05 2023-05-30 Jsr株式会社 光学传感器用组合物

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DE3782300T3 (de) 1998-02-19
EP0257364B2 (de) 1997-10-15
EP0257364B1 (de) 1992-10-21
DE3782300D1 (de) 1992-11-26
DE3782300T2 (de) 1993-03-04

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