EP0410414B1 - Two-component developer for use in dry development of electrostatic pattern - Google Patents

Two-component developer for use in dry development of electrostatic pattern Download PDF

Info

Publication number
EP0410414B1
EP0410414B1 EP19900114258 EP90114258A EP0410414B1 EP 0410414 B1 EP0410414 B1 EP 0410414B1 EP 19900114258 EP19900114258 EP 19900114258 EP 90114258 A EP90114258 A EP 90114258A EP 0410414 B1 EP0410414 B1 EP 0410414B1
Authority
EP
European Patent Office
Prior art keywords
toner
component
resin
relaxation time
component developer
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.)
Expired - Lifetime
Application number
EP19900114258
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0410414A1 (en
Inventor
Akihiro Watanabe
Tsutomu Uezono
Mitsushi Kuroki
Yoshihisa C/O Mita Industrial Co. Ltd. Kuramae
Naruo Yabe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Mita Industrial Co Ltd
Original Assignee
Mita Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mita Industrial Co Ltd filed Critical Mita Industrial Co Ltd
Publication of EP0410414A1 publication Critical patent/EP0410414A1/en
Application granted granted Critical
Publication of EP0410414B1 publication Critical patent/EP0410414B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • G03G9/083—Magnetic toner particles
    • 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
    • G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
    • G03G9/1075—Structural characteristics of the carrier particles, e.g. shape or crystallographic structure

Definitions

  • the present invention relates to a two-component developer for dry development of electrostatic pattern in electrophotography (this two-component developer will be hereinafter referred to as "dry two-component developer"). More particularly, it relates to an improved dry two-component developer which makes it possible to provide sufficiently sharp development of minute lines and dots and also to provide highly dense development of solid black area.
  • Japanese Laid-Open Sho. 60(1985)-170863 discloses a two-component developer containing magnetic carriers comprising ferrite particles of 5 x 107 ⁇ cm in specific resistance and of 50 to 120 ⁇ m in mean particle size.
  • the publication states that the two-component developer is effective to develop solid black areas with a uniform density without reducing resolution.
  • any of the foregoing proposals is directed to magnetic carrier particles for use in electrophotographic developers and those magnetic carrier particles are ones that have characteristics specified by the static condition but not by the dynamic condition which is necessary to be considered with respect to their characteristics upon contact of the developer's magnetic brush formed on the surface of the developing sleeve with the surface of the photosensitive member.
  • any of these known two-component developers is not sufficient to meet an increased demand for provision of an improved two-component developer which makes it possible to reproduce a desirable high quality image from an original containing multi-minute lines such as complicated chinese characters and black solid areas, which is not accompanied by any missing part and which excels in resolution and density (optical density).
  • the present invention is aimed at providing an improved dry two-component developer for use in electrophotography which is capable of providing sufficiently sharp development of minute lines and dots and is also capable of providing highly dense development of solid black area.
  • Another object of the present invention is to provide an improved dry two-component developer which is usable in various electrophotographic image-forming systems utilizing magnetic brush phenomenon.
  • a further object of the present invention is to provide an improved dry two-component developer for use in electrophotography which excels in charge retentivity, which slightly causes dispersion of toner particles and which excels in durability.
  • the dry two-component developer for use in electrophotography to be provided according to the present invention which attains the foregoing objects comprises a mixture composed of magnetic carrier particles and electroscopic toner particles (hereinafter referred to as "toner particles" in short) and satisfies the inequality: 0.35B+11 ⁇ A ⁇ 0.35B+14 with B being O ⁇ B ⁇ 20, wherein A represents a relaxation time (msec) of the developer in a dynamic state and B represents a relaxation time (msec) of the magnetic carrier particle in a dynamic state.
  • FIG. 1 is a schematic diagram illustrating the constitution of an experimental electrophotographic copying machine for measuring the relaxation time of a particle.
  • FIG. 2 is a schematic view showing the details of the electric circuit in the machine shown in FIG. 1.
  • FIG. 3 shows a graph obtained when an alternating voltage was applied onto the electric circuit shown in FIG. 2.
  • FIG. 4 collectively shows the interrelations among the relaxation times of the magnetic carrier particles, the relaxation times of the developers and the evaluated results on the resultant images reproduced.
  • FIG. 5 collectively shows the interrelations among the mean particle sizes of the magnetic carrier particles, the saturation magnetizations of said particles and the evaluated results on the resultant images reproduced.
  • FIG. 6 is a test chart for use in image-development test which contains plurality of parallel line groups.
  • FIGs. 7(a) to 7(c) show graphs respectively illustrating the interrelation between the distance of the developer to proceed and the image density (optical density) of the close minute line images reproduced from the test chart shown in FIG. 6.
  • the present inventors have made earnest studies for overcoming the foregoing problems in the known dry two-component developer and for attaining the objects as described above, and as a result, have experimentally found a fact that desirable reproduction of minute lines and high density reproduction of a black solid area can be desirably and effectively attained when a selected dry two-component developer comprising magnetic carrier particles and toner particles, the relaxation time of which in a dynamic state being in a specific range with respect to the relaxation time of the magnetic carrier particle in a dynamic state, is used as the developer in the electrophotographic image-forming system.
  • the present invention has been accomplished based on this finding.
  • the term "relaxation time in a dynamic state” means the relaxation time of the magnetic carrier particle or the developer when said magnetic carrier particle or said developer is situated in a state of forming a magnetic brush on a developing sleeve while moving in a developing mechanism of the electrophotographic image-forming system.
  • the relaxation time of the magnetic carrier particle or the developer is measured by using a partial modification of a commercially available electrophotographic copying machine DC-2585 (product by Mita Industrial Co., Ltd.) for use in experimental purposes in which the photosensitive selenium drum is replaced by a conductive drum 2 having an electrode surface made of brass and a measuring electric circuit system is provided as shown in FIG. 1.
  • FIG. 2 is a schematic view illustrating the constitution of said measuring electric circuit system.
  • numeral reference 1 stands for a developing sleeve provided with a magnetic pole therein (not shown).
  • Numeral reference 2 stands for a conductive drum of the same shape and the same size as those of the photosensitive drum.
  • Numeral reference 3 stands for a layer region composed of a two-component developer comprising magnetic carrier particles and toner particles or a layer region composed of said magnetic carrier particles which is formed in the space between the exterior of the conductive drum 2 and the exterior of the developing sleeve 1.
  • the conductive drum 2 and the developing sleeve 1 are rotated respectively at the nip position and in the direction expressed by an arrow.
  • Numeral reference 6 stands for a measuring digital oscillograph.
  • the developing sleeve 1 is electrically connected through a lead wire 4 to the oscillograph 6.
  • the conductive drum 2 is electrically connected through a lead wire 5 to the oscillograph 6.
  • Numeral reference 7 stands for an AC power source to which the developing sleeve 1 is electrically connected through the lead wire 4.
  • the relaxation time of the developer or the magnetic carrier particle is measured in the following manner. That is, the developing sleeve 1 and the conductive drum 2 are rotated; the AC power source 7 is switched on to apply an AC voltage of 50 Hz between said developing sleeve 1 and conductive drum 2 being rotating, where a voltage and an electric current are provided by the oscillogrph 6; and a phase difference between the resultant voltage and the resultant electric current is calculated to obtain a relaxation time (T) of the developer or the magnetic carrier particle.
  • FIG. 1 there exists the layer region 3 composed of the two-component developer or the magnetic carrier particles at the nip position between the developing sleeve 1 and the conductive drum 2.
  • Said layer region 3 can be approximated that a constant electrostatic capacity C and a constant electric resistance R are connected in parallel as shown in FIG. 2.
  • an electric current I is provided in the way as shown in FIG. 3. That is, an electric current iR flown to a resistance R (in FIG. 2) is of the same phase as the voltage V.
  • a electric current iC flown to a capacitor C (in FIG. 2) is of the phase exceeding the voltage V by 90°.
  • the entire electric current I is of the phase exceeding the voltage V by a value ⁇ .
  • the dry two-component developer for use in electrophotography according to the present invention is constituted by specific toner particles and specific magnetic carrier particles which are selected in combination such that the relaxation time (A)- obtained in the way above mentioned of the resulting dry two-component developer in a dynamic state becomes to satisfy the following inequality (1), wherein the relaxation time (B) obtained in the way above mentioned of said magnetic carrier particles in a dynamic state satisfies the following inequality(2): 0.35B+11 ⁇ A ⁇ 0.35B+14 O ⁇ B ⁇ 20
  • the dry two-component developer for use in electrophotography according to the present invention excels in resolution and tone reproduction. Particularly when an original containing close minute lines such as complicated chinese characters and solid black areas is used for reproduction, the resulting copied image becomes such that those complicated chinese characters are desirably reproduced with a high resolution without any missing part and solid black areas are reproduced with a desirably uniform optical density.
  • silicone resin straight silicone resin
  • acrylic resin MMA-BA copolymer
  • fluorine plastic mixed resin of polyvinylidene chloride and St-MMA copolymer
  • styrene resin hereinafter referred to as "resin D”
  • styrene-acrylic resin styrene-n-butylacrylate copolymer
  • Each of the ferrite particle Samples 1 to 24 was applied with a coat comprising one of said resins A to E in a predetermined amount by applying a coating composition containing said resin onto the ferrite particles, followed by drying with the use of a fluidized bed coating device.
  • the resultants were baking-finished at a temperature of 80 to 100°C and subjected to disintegrating granulation, to thereby obtain coated carrier particles.
  • resin-coated carrier particles for each of the ferrite particle samples Nos. 1 to 24.
  • Toner Sample 1 There were prepared three kinds of toner particles (Toner Sample 1, Toner Sample 2 and Toner Sample 3).
  • the composition was melt-blended, cooled, pulverized and classified, to thereby obtain toner particles of 10.5 ⁇ m in mean particle size, 2.2x10 ⁇ 9 S/cm in conductivity, 3.2 in dielectric constant and 13 in relaxation time (Toner Sample 1).
  • Toner Sample 2 The procedures of preparing Toner Sample 1 were repeated, except that the styrene-acrylonitrile copolymer was replaced by other styrene-acrylonitrile copolymer of 7.4x10 ⁇ 10 S/cm in conductivity, to thereby obtain toner particles of 10.5 ⁇ m in mean particle size, 3.2x10 ⁇ 9 S/cm in conductivity, 3.3 in dielectric constant and 9.5 in relaxation time (Toner Sample 2).
  • Toner Sample 3 The procedures of preparing Toner Sample 1 were repeated, except that the amount of the carbon black was increased to 10 parts by weight, to thereby obtain toner particles of 10.5 ⁇ m in mean particle size, 3.9x10 ⁇ 9 S/cm in conductivity, 3.5 in dielectric constant and 7.9 in relaxation time (Toner Sample 3).
  • Image-formation was performed with the use of each of the resultant Developer Samples Nos. 1 to 24 in a commercially available Electrophotographic Copying Machine DC-2585 of forward developing type (product by Mita Industrial Co., Ltd.) under the process conditions of the surface potential of the photosensitive drum: 800V; the magnetic brush bristle's interval: 1.0 mm; the distance between the developing sleeve and the photosensitive drum: 1.2 mm; the pherical speed ratio between the developing sleeve and the photosensitive drum: 2.73; and the intensity of the developing magnet: 0.08 T (800 Gauss).
  • each of the Developer Samples Nos. 3 and 15 respectively having a resin coated carrier particle of more than 20 in the dynamic state relaxation time provides unsatisfactory copied images of 1.15 to 1.25 in optical density but any of the remaining samples provides satisfactory copied images exceeding 1.25 in optical density.
  • the resin coated carrier sample No. 3 obtained in Experiment 1 was mixed with the toner sample 2 to thereby obtain a two-component developer A having a toner content of 2.8% by weight.
  • the resin coated carrier sample No. 3 obtained in Experiment 1 was mixed with the toner sample 3 obtained in Experiment 1 to thereby obtain a two-component developer B having a toner content of 2.8% by weight.
  • the resin coated carrier sample No. 15 obtained in Experiment 1 was mixed with the toner sample 2 to thereby obtain a two-component developer C having a toner content of 2.8% by weight.
  • the resin coated carrier sample No. 15 obtained in Experiment 1 was mixed with the toner sample 3 obtained in Experiment 1 to thereby obtain a two-component developer D having a toner content of 2.8% by weight.
  • Image-formation was performed with the use of each of the developer samples Nos. 1 to 24 in the same manner as in Experiment 1, wherein a test chart containing multiple minute lines which is shown in FIG. 6 was used as the original for reproduction.
  • the copied image obtained in each case was examined with respect to its image density (optical density) by the use of a reflection densitometer (Macbeth RD 914) to obtain the value shown in Table 2.
  • the test chart comprises 30 parallel line groups wherein 5 parallel line groups are arranged in the horizontal direction and 6 parallel line groups are arranged in the longitudinal direction, each parallel line group comprising 3 linear lines of the same length and the same thickness being arranged at regular intervals and in parallel to each other as shown in FIG. 6.
  • each parallel line group comprising 3 linear lines of the same length and the same thickness being arranged at regular intervals and in parallel to each other as shown in FIG. 6.
  • all the linear lines are the same in the line thickness.
  • the interval between every the two lines is constant.
  • the line thicknesses of the 5 parallel line groups belonging to the horizontal row are made 200, 140, 100, 70 and 50 ⁇ m respectively from the left to the right.
  • the intervals between every the two linear lines for the 6 parallel line groups in the longitudinal row are made 400, 300, 200, 140, 100 and 70 ⁇ m respectively from the top to the bottom.
  • This test chart is set to the electrophotographic copying machine such that the parallel lines of the test chart are in parallel to the rotary axis of the photosensitive drum and the test chart is reproduced.
  • the resultant reproduced is set to a commercially available SAKURA microdensitometer (product by KONICA Kabushiki Kaisha) which is capable of detecting the density of a thin line having a thickness less than the thickness of the thinnest line of the test chart, wherein the detecting area is adjusted to an area of 5 ⁇ m x 1 mm and one of the 30 parallel line groups as reproduced is crosswise scanned, to thereby observe changes of the density in the perpendicular direction.
  • SAKURA microdensitometer product by KONICA Kabushiki Kaisha
  • FIG. 7(a) shows the situation of the reproduced parallel line group wherein the width of each reproduced line is constant and equivalent to the original line without any missing defect at the top portion or the end portion of the line.
  • FIG. 7(b) shows the situation of the reproduced parallel line group wherein a significant missing defect is found at the top portion of the line.
  • FIG. 7(c) shows the situation of the reproduced parallel line group wherein a significant missing defect is found at the end portion of the line.
  • a mean value of the ⁇ for each parallel line group is obtained and the reproduced image is totally evaluated based on the resultant value of the ⁇ .
  • the ⁇ is in the range of 80 to 120 is considered to be satisfactory.
  • the case where the ⁇ is less than 80 is considered to be unsatisfactory because there is a distinguishable missing defect at the end portion of the line.
  • the case where the ⁇ is beyond 120 is considered to be unsatisfactory because there is a distinguishable missing defect at the top portion of the line.
  • the resultant copied image obtained in each case was evaluated totally based on the resultant value of the image density and the resultant value of the line width deviation ( ⁇ ).
  • the evaluated result was shown in Table 2 by the mark "O” or "X".
  • the mark “O” means the case which has a line width deviation ( ⁇ ) in the range of from 80 to 120 and has an image density of more than 1.25.
  • the mark “X” means the case which has a line width deviation ( ⁇ ) of less than 80 or more than 120, or has an image density of less than 1.25.
  • the evaluated results shown in Table 2 were collectively shown in FIG. 4 with relation to the relaxation time A of the developer sample in a dynamic state and the relaxation time B of the resin-coated carrier sample thereof in a dynamic state. And there were obtained four linear lines a, b, c and d as shown in FIG. 4.
  • the resin-coated carrier particle samples which provided satisfactory results when used in combination with the toner samples in Experiment 3 were plotted with interrelation to the particle size D ( ⁇ m) and the saturation magnetization M (wb/g) as shown in FIG. 5, wherein the resin-coated carrier particle samples which provided high quality copied images having an image density of more than 1.3 and a line width deviation of more than 85 were expressed respectively by the mark "o" and the remaining resin-coated carrier particle samples were expressed respectively by the mark "o".
  • the two-component developer of the present invention is inclusively specified by the relaxation time A when it is situated in a dynamic state, which satisfies the foregoing inequality: 0.35B+11 ⁇ A ⁇ 0.35B+14 with B being greater than zero (0) but less than 20, wherein B represents the relaxation time of the magnetic carrier component of said developer.
  • Said relaxation time A of the two-component developer of the present invention can be adjusted as desired by properly varying the capacitive component (C) and the resistant medium (R) to be used in combination.
  • the relaxation time A can be heightened by increasing the amount of the capacitive component (C) or the resistant medium (R).
  • the relaxation time A can be reduced by decreasing the amount of the capacitive component (C) or the resistant medium (R).
  • due regards are to be made on the shape, particle size, specific resistance, and dielectric constant not only for the magnetic carrier component but also for the toner component, and further due regards are to be made on the mixing ratio of the magnetic carrier component and the toner component.
  • magnetic carrier component magnetic carrier particles
  • toner component to constitute the two-component developer of the present invention.
  • the magnetic component is an important factor to make the two-component developer of the present invention to be desirable one which is capable of providing image-developing characteristics as desired in the electrophotographic image-forming process.
  • the magnetic component to be used in the present invention comprises a magnetic core particle having a resin coat applied on the surface thereof.
  • the magnetic component comprising said magnetic core particle having the resin coat is required to have a dielectric constant preferably in the range of from 4 to 15 or more preferably in the range of from 5 to 9 and a volume resistivity preferably in the range of from 5x109 to 5x1011 or more preferably in the range of from 4x1010 to 1x1011 ⁇ cm.
  • said magnetic component is required to have a relaxation time B which satisfies the inequality: O ⁇ B ⁇ 20.
  • ferrites containing one or more elements selected from the group consisting of Cu, Zn, Mg, Mn and Ni.
  • ferrites composed of Cu, Zn and Mg are the most desirable.
  • ferrites Other than these ferrites, it is possible to use other commercially available ferrites such as ZnFe2O4, Y3Fe5O12, CdFe2O4, CdFe5O12, PbFe12O19, NiFe2O4,NdFeO3, BaFeO12O19, MgFe2O4, MnFe2O4, LaFeO3, etc.
  • ferrites such as ZnFe2O4, Y3Fe5O12, CdFe2O4, CdFe5O12, PbFe12O19, NiFe2O4,NdFeO3, BaFeO12O19, MgFe2O4, MnFe2O4, LaFeO3, etc.
  • the magnetic core particle may be comprised of one or more kinds selected from those ferrites mentioned above.
  • the foregoing relaxation time of the magnetic component is decided depending upon the kind and the amount of a coating resin applied on the surface of the magnetic core particle.
  • the amount of the coating resin applied on the surface of the magnetic core particle it should be preferably in the range of from 0.5 to 30 parts by weight or more preferably, in the range of from 0.8 to 1.5 parts by weight respectively on the basis of a dry weight, versus 100 parts by weight of the ferrite constituting the magnetic core particle.
  • the amount of said coating resin applied should be decided to be in the above range so that the resulting magnetic component results in having a relaxation time B to satisfy the inequality: O ⁇ B ⁇ 20 when it is situated in the foregoing dynamic state.
  • the coating resin are silicone resin, fluorine plastic, acrylic resin, styrene resin, styrene-acryl resin, olefin resin, ketone resin, phenol resin, xylene resin, diallyl phthalate resin, etc.
  • straight silicone resin is the most desirable.
  • said straight silicone resin are net-structured silicone resins comprising organopolysiloxane such as dimethylpolysiloxane, diphenylsiloxane or methylphenylpolysiloxane.
  • Said net-sturctured silicone resins may be obtained by incorporating hydrolyzable functional group such as trimethoxy group or other functional group such as silanol group into the organopolysiloxane unit, if necessary followed by hydrolysis, and contacting the resultant with a condensation catalyst.
  • These resins may be used singly or in combination of two or more of them.
  • the toner component comprising toner particles to be used in combination of the foregoing magnetic component to obtain the two-component developer of the present invention is required to have a specific dynamic state relaxation time such that makes the resulting two-component developer comprised of the foregoing magnetic component and the toner component to satisfy the inequality: 0.35B+11 ⁇ A ⁇ 0.35B+14.
  • a carbon black excelling in conductivity in a relatively large amount and a toner resin having a relatively low electrical resistivity.
  • toner resin Usable as such toner resin are polar group-containing resins such as acrylic resin and acryl-styrene copolymer resin.
  • acrylic resin examples are resins comprising acrylic monomer of the formula (1): , wherein R1 is hydrogen atom or a lower alkyl group, R2 is hydrogen atom or an alkyl group containing up to 18 carbon atoms.
  • acrylic monomer examples include ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, methacrylic acid, etc.
  • said acrylic monomer may be ethylenic unsaturated carboxylic acids, anhydrides of said carboxylic acids such as maleic acid, crotonic acid, itaconic acid or anhydrides of these acids.
  • acryl-styrene copolymer resins comprising the foregoing acrylic monomer represented by aforesaid formula (1) and styrenic monomer of the formula (2): , wherein R3 is hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, or halogen atom, R4 is a lower alkyl group or halogen atom, and n is an integer of 2 or more.
  • styrenic monomer examples include styrene, vinyltoluene, ⁇ -methylstyrene, ⁇ -chlorostyrene, vinylxylene and vinylnaphthalene, among these, styrene being the most desirable.
  • Any of the foregoing resins is desired to be of an oxidation number preferably in the range of from 0 to 25 or more preferably, in the range of from 5 to 10.
  • the carbon black having a large structure-forming ability means such a carbon black that is minute in particle size, has a large BET relative surface, for example, of more than 50 m/g, is large in oil absorption and is capable of providing a chain structure or a fringed-micelle structure within the toner resin.
  • the amount of the highly conductive carbon black to be incorporated into the toner component is preferably in the range of from 2 to 20 parts by weight or more preferably in the range of from 5 to 10 parts by weight respectively versus 100 parts by weight of the toner resin.
  • the toner component to constitute the two-component developer of the present invention may-contain a relevant charge controlling agent.
  • the charge controlling agent can include oil soluble dyes such as nigrosine base (CI 50415), spiron black (CI 26150), etc.; metal complex salt dyes of the 1:1 type or the 2:1 type; naphthenic metal salts; fatty acid soaps; and resinic acid soaps.
  • the toner particles to constitute the toner component of the present invention are desired to range in median diameter preferably from 8 to 14 ⁇ m or more preferably from 10 to 12 ⁇ m when measured by a coalter counter.
  • the toner particles may be of undefined shapes obtained by a melt-blending pulverization method or of spherical shapes obtained by a dispersion or suspension polymerization method.
  • the two-component developer according to the present invention comprises the foregoing magnetic component and the foregoing toner component and is specified by having a dynamic state relaxation time A which satisfies the foregoing inequality: 0.35B+11 ⁇ A ⁇ 0.35B+14.
  • the two-component developer according to the present invention is prepared by mixing a magnetic component selected from the magnetic components mentioned above and a toner component selected from the toner components mentioned above with the mixing ratio which has been predetermined while considering the characteristics and the dynamic state relaxation times of the two components to be mixed so that the resulting two-component has a dynamic state relaxation time A to satisfy the above equation.
  • the mixing ratio of the magnetic component to the toner component in order to obtain the two-component developer of the present invention should be decided preferably in the range of from 99:1 to 90:10, more preferably in the range of from 98:2 to 95:5 respectively in terms of the quantitative mixing ratio.
  • the two-component developer of the present invention can be used in any of the known electrophotographic copying systems in which a two-component developer is used for image reproduction. And in any case, there can be stably provided high quality copied images excelling in resolution, tone reproduction and image density.
  • the two-component developer of the present invention provides significant effects when an original containing multiple minute lines such as complicated chinese characters is used for reproduction. That is, there can be stably and repeatedly obtained high quality images equivalent to the original in which those complicated chinese characters of the original are desirably reproduced with high resolution and in high image density without any missing part.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Developing Agents For Electrophotography (AREA)
EP19900114258 1989-07-28 1990-07-25 Two-component developer for use in dry development of electrostatic pattern Expired - Lifetime EP0410414B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP19405889 1989-07-28
JP194058/89 1989-07-28

Publications (2)

Publication Number Publication Date
EP0410414A1 EP0410414A1 (en) 1991-01-30
EP0410414B1 true EP0410414B1 (en) 1996-02-21

Family

ID=16318248

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900114258 Expired - Lifetime EP0410414B1 (en) 1989-07-28 1990-07-25 Two-component developer for use in dry development of electrostatic pattern

Country Status (3)

Country Link
EP (1) EP0410414B1 (ja)
JP (1) JP2941378B2 (ja)
DE (1) DE69025436T2 (ja)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3187582B2 (ja) * 1992-06-15 2001-07-11 京セラ株式会社 静電潜像用現像剤および画像形成方法
JP5106148B2 (ja) * 2007-03-16 2012-12-26 株式会社リコー 電子写真現像剤用キャリア、現像剤、及び画像形成方法
JP2008281935A (ja) * 2007-05-14 2008-11-20 Sharp Corp キャリア、現像装置および画像形成装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764445A (en) * 1987-06-15 1988-08-16 Eastman Kodak Company Electrographic magnetic carrier particles

Also Published As

Publication number Publication date
JPH03121467A (ja) 1991-05-23
EP0410414A1 (en) 1991-01-30
JP2941378B2 (ja) 1999-08-25
DE69025436T2 (de) 1996-07-04
DE69025436D1 (de) 1996-03-28

Similar Documents

Publication Publication Date Title
US4948686A (en) Process for forming two-color images
EP0708376A2 (en) Two-component type developer, developing method and image forming method
US4609603A (en) Process for achieving consistent high quality images with magnetic developer composition
EP0516434B1 (en) Magenta toner compositions
US4336318A (en) Electrostatic image developing method
EP0410414B1 (en) Two-component developer for use in dry development of electrostatic pattern
JPH11184167A (ja) 静電潜像現像用キャリア、静電荷像現像剤及び画像形成方法
US5217835A (en) Two-component developer for use in dry development of electrostatic pattern
JPS61180247A (ja) 静電潜像用現像剤
US5212038A (en) Developer and process for preparation thereof
JPH11125966A (ja) 現像剤担持体、装置ユニット及び画像形成装置
JP3397543B2 (ja) 二成分系現像剤、現像方法及び画像形成方法
JP3495313B2 (ja) 磁性一成分現像剤及びその現像方法
JP3173321B2 (ja) 現像方法
JP4107431B2 (ja) トナー、並びに、現像剤、トナー入り容器、プロセスカートリッジ、画像形成装置及び画像形成方法
US4912003A (en) Reverse development method
US5506084A (en) Magnetic developer and developing device using same
US4653896A (en) Process for developing and transferring magnetic toner images
JPS5834829B2 (ja) 電子写真用現像剤
JP2001159829A (ja) 磁性一成分現像剤及びその現像方法
JPS59121056A (ja) 現像方法
JPH073610B2 (ja) 非晶質シリコン系光導電層の高速現像方法
JPS5915260A (ja) 現像方法
GB2103816A (en) Mono-component toner for magnetic brush development of electrostatic latent images
JPH03186858A (ja) 高画質現像方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): CH DE FR GB IT LI NL

17P Request for examination filed

Effective date: 19901217

17Q First examination report despatched

Effective date: 19941031

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): CH DE FR GB IT LI NL

ITF It: translation for a ep patent filed

Owner name: STUDIO CONS. BREVETTUALE S.R.L.

REF Corresponds to:

Ref document number: 69025436

Country of ref document: DE

Date of ref document: 19960328

REG Reference to a national code

Ref country code: CH

Ref legal event code: NV

Representative=s name: RITSCHER & SEIFERT PATENTANWAELTE VSP

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20000711

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20000728

Year of fee payment: 11

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020329

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 20020201

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20050720

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20050721

Year of fee payment: 16

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050725

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 20050727

Year of fee payment: 16

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060725

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060731

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060731

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070201

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20060725