EP0003134A1 - Magnetbürsten-Entwicklungsvorrichtung - Google Patents

Magnetbürsten-Entwicklungsvorrichtung Download PDF

Info

Publication number
EP0003134A1
EP0003134A1 EP79100081A EP79100081A EP0003134A1 EP 0003134 A1 EP0003134 A1 EP 0003134A1 EP 79100081 A EP79100081 A EP 79100081A EP 79100081 A EP79100081 A EP 79100081A EP 0003134 A1 EP0003134 A1 EP 0003134A1
Authority
EP
European Patent Office
Prior art keywords
magnetic
magnetic pole
pole portion
magnet
electrostatic image
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
EP79100081A
Other languages
English (en)
French (fr)
Other versions
EP0003134B1 (de
Inventor
Manabu Mochizuki
Masahide Harada
Mitsuo Tanaka
Kouji Suzuki
Kazuaki Tagawa
Kazuo Kobayashi
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.)
Ricoh Co Ltd
Original Assignee
Ricoh 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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=26335093&utm_source=***_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0003134(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Priority claimed from JP180878A external-priority patent/JPS5495243A/ja
Priority claimed from JP2956978A external-priority patent/JPS54122131A/ja
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to DE8080107642T priority Critical patent/DE2967496D1/de
Publication of EP0003134A1 publication Critical patent/EP0003134A1/de
Application granted granted Critical
Publication of EP0003134B1 publication Critical patent/EP0003134B1/de
Expired 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
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G03G15/0921—Details concerning the magnetic brush roller structure, e.g. magnet configuration

Definitions

  • the present invention relates to a magnetic brush development apparatus for use in electrophotographic copying apparatus or electrostatic recording apparatus.
  • the magnetic brush development apparatus is an apparatus for attracting a developer containing magnetic powder therein to a non-magnetic support member in which magnets are disposed, and for bringing the developer into contact with a latent electrostatic image bearing member at an image development section in order to develop the latent electrostatic image.
  • the name of the magnetic brush comes from that the developer becomes like a brush due to the magnetic force of the magnets disposed in the non-magnetic support member.
  • the developer that can be employed in the magnetic brush development apparatus there are a two-component type developer comprising non-magnetic toner and magnetic carrier, and a one-component type developer consisting of magnetic toner.
  • the one-component type developer can be classified into an electrically conductive toner and an electrically insulating toner.
  • Image development is performed by the toner charged to the opposite polarity to :,hat of a latent electrostatic image being electrostatically attracted to the latent Image development is performed by the toner cha Z ed to the opposite polarity to that of a latent electrostatic image being electrostatically attracted to the latent electrostatic image.
  • the particle size of toner is smaller than that of carrier particles and rhe toner is triboelectrically charged so that the toner clings to the carrier and a magnetic brush is formed.
  • the electrically conductive toner is charged by injection of charges or by electrostatic induction, while the electrically insulating toner is triboelectrically charged by some member of a developer container with which the toner contacts or during the transportation of the toner.
  • the toner In case of the two-component type developer, the toner is securely charged, but some means for maintaining the mixing ratio of the toner and the carrier or the toner concentration is necessary in order to obtain a developed image of a predetermined image density. In contrast to this, in case of the one-component type developer, it is unnecessary to control the toner concentration and simple in handling the toner although the charging of the toner is not always sufficient.
  • a sleeve-shaped or cylindrical member and an endless belt- shaped member are known as the non-magnetic supporting members for forming a magnetic brush thereon by attracting the developer thereto.
  • Plural magnets arranged in a radial manner and a single rod magnet having magnetic poles on the peripheral surface thereof are known as the magnets to be disposed in the non-magnetic support member.
  • the photoconductors for use in electrophotographic copying apparatus and the dielectric member for electrostatic recording apparatus are known as the latent image bearing members.
  • the shapes of the latent image bearing members are drum-like, endless-belt-like, plate-like and sheet- like.
  • Either or both of the non-magnetic support member for holding the magnetic brush thereon and the magnets disposed inside the non-magnetic support member are moved relative to each other, so that the magnetic brush formed on the non-magnetic support member is moved on the non-magnetic supporting member.
  • the latent image bearing member is also moved at a predetermined speed and the magnetic brush on the non-magnetic supporting member comes in contact with the surface of the latent electrostatic image bearing member at a predetermined position where the non-magnetic support member and the latent electrostatic image bearing member come closest to each other, namely at a development section, so that the latent electrostatic image on the latent image bearing member is developed continuously.
  • the magnetic brushes on the non-magnetic support member are formed along the lines of magnetic force distributed on the non-magnetic supporting member 1 among the magnets 2, 3 , 4 and 5 which are disposed in the non-magnetic support member as shown in Fig. 1.
  • Fig.l the distribution of the magnetic lines of force among only the magnets 2, 3 and 4 are shown.
  • Each line of magnetic force starts from the magnetic pole N and returns to the magnetic pole S, and the magnetic field is strongest at each magnetic pole.
  • the magnetic brush becomes highest a each magnetic pose and lowest inbetween each pole.
  • the magnetic brush stands out at each magnetic pole as shown by reference numberal 6 in Fig. 2. Therefore, normally, the magnets are arranged so that each magnetic Dole of the magnets is located in the development section and development is performed by the highest portion of the magnetic brush.
  • the image density of developed image depends upon development time.
  • the development time here means a period of time in which developer is in contact with a latent electrostatic image bearing member. Therefore, in the magnetic brush development apparatus, the development time is a period of time in which the magnetic brush is in contact with a latent electrostatic image bearing member at the development position.
  • the period of time in which the magnetic brush is in contact with the latent image bearing member is related to the contact width w of the magnetic brush in contact with the latent image bearing member. Therefore, the development efficiency, namely the image density of developed image per unit time can be increased by broadening the contact width w.
  • a one of the conventional techniques for making the contact width w great an apparatus is known in which a plurality of non-magnetic support members for supporting the magnetic brush thereon are disposed in close proximity to the surface of a latent electrostatic image bearing member, whereby the contact width w can be substantially increased.
  • this apparatus has some shortcomings that the apparatus is oversized and expensive. In order to eliminate such shortcomings, it is necessary to increase the contact width w by a single non-magnetic supporting member.
  • the contact width w of the magnetic brush is related to a gap d in the development section between a latent electrostatic image bearing member 7 and a non-magnetic support member 1 since the magnetic brush stands out at each magnetic pole.
  • the contact width w is greater in the bottom portion of the magnetic brush than in the top portion of the magnetic brush. Therefore, the smaller the gap d, the greater the contact width w.
  • the gap d is related to the contact width w and accordingly to the development time, images with an uneven density are formed when the gap d changes during development.
  • a spacer roller is disposed between a non-magnetic sleeve and a photoconductor in order to maintain a minimum gap d.
  • the magnetic toner or the magnetic carrier existing on the portion above the space between the two magnets is magnetized in the polarity opposite to that of the magnetic toner ort ⁇ e magnetic carrier in the other portion, so that the chainlike arrangement of the toner or the carrier is interrupted by the two magnets.
  • the oppositely directed magnetic fields of the two magnets 8 and 9 are shown in Fig. 5, in which the lines of magnetic force starting from the N pole are directed to the N pole in the respective magnets 8 and 9, so that the lines of magnetic force starting from the respective N poles are oppositely directed.
  • the development force can be represented by the following formula: where F represents the development force, and Fc represents the electrostatic attraction of a photoconductor for attracting the developer thereto, and F represents the magnetic attraction for attracting the developer magnetically in the magnetic brush development apparatus.
  • the magnetic attraction F M serves as a negative bias with respect to the development force in the magnetic brush development apparatus.
  • Fig. 14 there is shown a development characteristic of the magnetic brush development, by employing the magnetic attraction F as a parameter, with the amount of toner deposition M as ordinate and surface charge Q of a photoconductor as abscissa.
  • the solid line indicates a development characteristic when the magnetic attraction F M is comparatively small while the broken line indicates a development characteristic when the magnetic attraction F M is comparatively great. In either case, the development time is set constant.
  • the magnetic attraction F m when the magnetic attraction F m is small, the toner deposition begins to be saturated even if the surface charge Q is comparatively small.
  • the magnetic attraction F M when the magnetic attraction F M is set small, the amount of toner deposition M during a predetermined development time becomes greater than that in the case where the magnetic attraction FM is set great and accordingly, the development time can be shortened in comparison with that in the case of a great magnetic attraction F when an equal amount of toner deposition is required.
  • the magnetic attraction F M when the magnetic attraction F M is set small, background appears in the copy and sharpness of image is lowered, so that setting the magnetic attraction F M at a low level has an adverse effect on the image quality.
  • a magnet disposed in a non-magnetic support member can generate a magnetic field having a plurality of peaks in the distribution of the intensity of the magnetic field and has substantially one magnetic pole portion in the development section.
  • Another object of the invention is to provide a magnetic brush development apparatus having an excellent development efficiency with uneven development obviated by broadening the width of a magnetic brush which is in contact with a latent electrostatic image bearing member.
  • a further object of the invention is to provide a magnetic brush development apparatus whose construction is simple and which can be assembled easily.
  • the magnet in a magnetic brush development apparatus having a non-magnetic sleeve and a magnet disposed inside the non-magnetic sleeve for producing a magnetic field on zhe outer peripheral surface of the non-magnetic sleeve, the magnet has substantially one magnetic pole portion capable of producing a magnetic field having a plurality of peaks in the intensity of the magnetic field and the peaks located upstream of the movement of a latent electrostatic imag g bearing photoconductor are lower than the peaks located downstream of the movement of the latent electrostatic image bearing photoconductor.
  • a magnet for one embodiment of a magnetic brush development apparatus of the present invention there is shown a magnet for one embodiment of a magnetic brush development apparatus of the present invention.
  • a magnet 11 having a flat concave portion of the magnet 11 is disposed under a non-magnetic supporting element 10. The opposite end portions of the magnet 11 are projected.
  • a magnet 12 has a curved concave portion in the central portion thereof and accordingly the opposite end portions of the magnet 12 are projected towards the non-magnetic supporting elment 10.
  • the distribution of the intensity of magnetic field of the magnets having a concave portion in the central portion thereof is shown in Fig. 8.
  • Fig. 8 The distribution of the intensity of magnetic field of the magnets having a concave portion in the central portion thereof.
  • the long and short dash line indicates the distribution of the intensity of magnetic field of a conventional flat magnet, which has one peak of the intensity of magnetic field
  • the solid line indicates the distribution of the intensity cf the magnetic field of the magnets of the present invention, which has two peaks of the intensity of the magnetic field.
  • the shape of the curve having two peaks of the intensity of magnetic field depends upon the size of the concave portion formed in the magnet. Namely, when the width a of the concave portion of the magnet is constant and the dpeth b of the concave portion is changed, the greater the depth b, the greater central dropping of the curve of the intensity of magnetic field, and when the depth b is constant and the width a changes, the greater the width a, the lower the two peaks.
  • the ratio a : b is 4 : 1
  • the distribution of the intensity of magnetic field is shown by the solid line 14 and, when the ratio a : b is 4 : 2
  • the distribution of the intensity of magnetic field is shown by a broken
  • a magnet 16 which has two concave portions, each of which has a width a and a depth b.
  • the distribution of the intensity of magnetic field becomes like a curve indicated by the broken line 17 in Fig. 10.
  • the curve of the distribution of the intensity of magnetic field is a broad curve having a small and uniform central dropped portion.
  • the distribution of the intensity of magnetic field of the magnet can be changed so as to have three or more peaks.
  • a different distribution of the intensity of magnetic force can be formed on the non-magnetic support member by changing the shape of the magnet.
  • the magnets for the present invention can be made by various methods.
  • the simplest method is to mold a ferromagnetic material and magnetize it and form a concave portion in the thus made magnet as desired by a diamond cutter.
  • Another method is to form a desired concave portion in a ferromagnetic material first and to magnetize it later.
  • a further method is to join together magnets or cause a ferromagnetic material to adhere to the projecting portions of a magnet.
  • the magnets are composed of pieces of magnets.
  • one magnetic rod with predetermined concave portions at desired magnetic pole portions can be used as well.
  • the magnetic toner or the magnetic carrier on the non-magnetic support member is magnetized uniformly in the same direction as shown in Fig. 11, so that a stable magnetic brush is formed on the non-magnetic support member.
  • the magnetic brush of the present invention is gently sloping at the magnetic pole portions when the non-magnetic support member 10 and the magnet 11 are stopped.
  • the magnetic brush is is divided into two as shown in Fig. 12 by a slight shock due to the gradient force of the magnetic field gradient.
  • the two divided magnetic brushes are made into one magnetic brush as the non-magnetic support member 10 or the magnet 11 is moved since the variation of the magnetic field intensity is continuously effected over the magnetic toner or the magnetic carrier on the non-magnetic support member as shown in Fig. 13.
  • the thus formed magnetic brush has a small toner density and the t ocking of toner does not occur when the development gap is narrowed.
  • FIG. 15 there is schematically shown a further magnetic brush development apparatus according to the present invention.
  • reference numeral 21 represents a non-magnetic sleeve which is rotated counterclockwise.
  • a magnet 22 In the non-magnetic sleeve 21, there is disposed a magnet 22.
  • Part of the non-magnetic sleeve 21 faces a drum- shaped latent electrostatic image bearing member or a photoconductor drum 23 with a predetermined space therebetween.
  • the magnet 22 has a magnetic pole, for instance, an N pole, facing the surface of the photoconductor drum 23 through the non-magnetic sleeve 21 in a development section, so that a magnetic field is formed in the development section on the non-magnetic sleeve 21.
  • a magnet (not shown) for transporting developer is incorporated in the non-magnetic sleeve 21.
  • a groove 24 which is eccentrically located closer to the surface of the photoconductor drum 23.
  • a first magnetic pole portion 25 is formed in the magnet 22, upstream of the groove 24, and a second magnetic portion 26 is formed downstream of the groove 24.
  • the first magnetic portion 25 is broader than the second portion 26.
  • the developer in developing a latent electrostatic image on the photoconductor drum 23, firstly the developer is deposited uniformly on the latent electrostatic image by the comparatively weak magnetic field produced by the first magnetic pole portion 25 which is located upstream in view of the rotation of the photoconductor drum 23, and secondly the latent electrostatic image is completely developed by the comparatively strong magnetic field produced by the second magnetic pole portion 26 which is located downstream of the first magnetic pole portion 25, whereby a high quality image with a uniform image density and without background can be obtained.
  • Fig. 18 there is shown partially an enlarged schematic sectional view of a further embodiment of the present invention.
  • a first magnetic pole portion 27 which is formed with a predetermined first space away from the outer peripheral surface of the non-magnetic sleeve 21, and a second magnetic pole portion 28 with a second space away from the outer peripheral surface of the non-magnetic sleeve 21.
  • the first space is greater than the second space, so that the second magnetic pole portion 28 constitutes a stepped end portion of the magnetic pole portion of Fig. 18.
  • the first magnetic pole portion 27 is located upstream of the second magnetic pole portion 28, viewed from the rotation of the photoconductor drum 23.
  • the intensity of the magnetic field is distributed as shown in Fig. 19, so that the effect similar to that of the embodiment of Fig. 16 can be obtained.
  • Fig. 20 there is shown partially an enlarged schematic sectional view of a still further embodiment of the present invention.
  • the magnetic pole portion of the magnet of this embodiment there are formed two grooves 39 and 30 which are spaced away from each other, and a first magnetic pole portion 31, a second magnetic pole portion 32, and a third magnetic pole portion 33 which are separated by the two grooves 39 and 30.
  • the first and second magnetic pole portions 31 and 32 which are located upstream of the third magnetic pole portion 33, are equally spaced away from the outer peripheral surface of the non-magnetic sleeve 21, while the third magnetic pole portion 33 is located closer to the non-magnetic sleeve 21 than the first two magnetic pole portions 31 and 32.
  • the curve of the intensity of the magnetic field has three peaks as shown in Fig. 21. Of the three peaks of the intensity of the magnetic field, the peak existing most downstream of the rotation of the photoconductor drum 23 is the highest, which indicates the greatest magnetic force.
  • the developer is deposited uniformly on a latent electrostatic image on the drum 23 by the comparatively weak magnetic field of the first and second magnetic pole portions 31 and 32 and the latent image is the completely developed by the comparatively strong magnetic field produced by the third magnetic pole portion 33.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
EP19790100081 1978-01-11 1979-01-11 Magnetbürsten-Entwicklungsvorrichtung Expired EP0003134B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE8080107642T DE2967496D1 (en) 1978-01-11 1979-01-11 Magnetic brush development apparatus

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP1808/78 1978-01-11
JP180878A JPS5495243A (en) 1978-01-11 1978-01-11 Magnetic brush developing device
JP2956978A JPS54122131A (en) 1978-03-15 1978-03-15 Magnetic brush developing device
JP29569/78 1978-03-15

Related Child Applications (1)

Application Number Title Priority Date Filing Date
EP80107642.3 Division-Into 1980-12-04

Publications (2)

Publication Number Publication Date
EP0003134A1 true EP0003134A1 (de) 1979-07-25
EP0003134B1 EP0003134B1 (de) 1981-10-14

Family

ID=26335093

Family Applications (2)

Application Number Title Priority Date Filing Date
EP80107642A Expired EP0031503B1 (de) 1978-01-11 1979-01-11 Magnetbürsten-Entwicklungsapparat
EP19790100081 Expired EP0003134B1 (de) 1978-01-11 1979-01-11 Magnetbürsten-Entwicklungsvorrichtung

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP80107642A Expired EP0031503B1 (de) 1978-01-11 1979-01-11 Magnetbürsten-Entwicklungsapparat

Country Status (2)

Country Link
EP (2) EP0031503B1 (de)
CA (1) CA1135046A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0349326A2 (de) * 1988-07-01 1990-01-03 Canon Kabushiki Kaisha Entwicklungsgerät
EP0163136B1 (de) * 1984-04-27 1991-03-13 Kabushiki Kaisha Toshiba Vorrichtung zum Feststellen der Tonerdichte

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2018561A2 (de) 2006-05-10 2009-01-28 Koninklijke Philips Electronics N.V. Magnetisches system
JP6938167B2 (ja) 2016-03-08 2021-09-22 キヤノン株式会社 画像形成装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7104099U (de) * 1971-07-08 Addressograph Multigraph Corp Magnetbürstenentwickler zum Entwickeln elektrostatisch geformter Bilder auf Blatt material
DE1572348B2 (de) * 1966-06-06 1973-08-02 Konishiroku Photo Industry Co., Ltd., Tokio Vorrichtung zum erzeugen einer magnetischen entwicklungsbuerste fuer elektrophotographische kopierverfahren
US3839992A (en) * 1971-02-13 1974-10-08 Ricoh Kk Diazo type photosensitive sheet developing device
DE2545494A1 (de) * 1974-10-10 1976-04-22 Canon Kk Entwicklungseinrichtung
DE2452879A1 (de) * 1974-11-07 1976-05-20 Hitachi Metals Ltd Elektrostatische entwicklungsvorrichtung
DE2611755A1 (de) * 1976-03-08 1977-09-22 Fuji Xerox Co Ltd Magnetbuersten-entwicklungsvorrichtung

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3333572A (en) * 1965-04-27 1967-08-01 Rca Corp Electrostatic printing
US3939801A (en) * 1973-09-10 1976-02-24 Minolta Camera Kabushiki Kaisha Magnetic brush developing apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7104099U (de) * 1971-07-08 Addressograph Multigraph Corp Magnetbürstenentwickler zum Entwickeln elektrostatisch geformter Bilder auf Blatt material
DE1572348B2 (de) * 1966-06-06 1973-08-02 Konishiroku Photo Industry Co., Ltd., Tokio Vorrichtung zum erzeugen einer magnetischen entwicklungsbuerste fuer elektrophotographische kopierverfahren
US3839992A (en) * 1971-02-13 1974-10-08 Ricoh Kk Diazo type photosensitive sheet developing device
DE2545494A1 (de) * 1974-10-10 1976-04-22 Canon Kk Entwicklungseinrichtung
DE2452879A1 (de) * 1974-11-07 1976-05-20 Hitachi Metals Ltd Elektrostatische entwicklungsvorrichtung
DE2611755A1 (de) * 1976-03-08 1977-09-22 Fuji Xerox Co Ltd Magnetbuersten-entwicklungsvorrichtung

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0163136B1 (de) * 1984-04-27 1991-03-13 Kabushiki Kaisha Toshiba Vorrichtung zum Feststellen der Tonerdichte
EP0349326A2 (de) * 1988-07-01 1990-01-03 Canon Kabushiki Kaisha Entwicklungsgerät
EP0349326A3 (en) * 1988-07-01 1990-11-28 Canon Kabushiki Kaisha A developing apparatus

Also Published As

Publication number Publication date
EP0031503B1 (de) 1985-08-07
EP0031503A2 (de) 1981-07-08
CA1135046A (en) 1982-11-09
EP0003134B1 (de) 1981-10-14
EP0031503A3 (en) 1981-09-09

Similar Documents

Publication Publication Date Title
US4121931A (en) Electrographic development process
US4387664A (en) Developing apparatus for electrostatic image
US5451713A (en) Developing apparatus using a developer carrier capable of forming microfields
US5286918A (en) Developing apparatus using a developer carrier capable of forming microfields on the surface thereof
US4292387A (en) Magnetic developing method under A.C. electrical bias and apparatus therefor
US4331100A (en) Magnetic brush development apparatus
US3645770A (en) Improved method for developing xerographic images
US4887131A (en) Developing apparatus using magnetic particles and toner particles
NL8320383A (nl) Electrografische ontwikkelaarsamenstelling en werkwijze voor het gebruik daarvan.
US4349270A (en) Developer removing device for copying apparatus
US4561381A (en) Voltage-controlled developing device
US4486089A (en) Magnetic brush developing means
JPS61223769A (ja) 一成分現像装置
US5194359A (en) Developing method for one component developer
EP0003134A1 (de) Magnetbürsten-Entwicklungsvorrichtung
US4336318A (en) Electrostatic image developing method
US4389113A (en) Improved developing device for two-color electrophotographic copying apparatus
US4303331A (en) Magnet for use in a magnetic brush development system
US5012288A (en) Dry toner development
JPS6255149B2 (de)
JPS6316738B2 (de)
US4499166A (en) Method of developing an electrostatic latent image uses magnetic developer
JPH0132505B2 (de)
US3836384A (en) Imaging systems
JPH05134552A (ja) 現像ローラー・現像ローラー着磁用ヨークおよび現像ローラー着磁方法

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

Designated state(s): DE FR GB

17P Request for examination filed
GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 2960948

Country of ref document: DE

Date of ref document: 19811224

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

26 Opposition filed

Opponent name: SIEMENS AG, BERLIN UND MUENCHEN

Effective date: 19820714

PLBN Opposition rejected

Free format text: ORIGINAL CODE: 0009273

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

Free format text: STATUS: OPPOSITION REJECTED

27O Opposition rejected

Effective date: 19830722

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

Ref country code: GB

Payment date: 19980102

Year of fee payment: 20

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

Ref country code: FR

Payment date: 19980109

Year of fee payment: 20

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

Ref country code: DE

Payment date: 19980116

Year of fee payment: 20

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 EXPIRATION OF PROTECTION

Effective date: 19990110

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Effective date: 19990110