EP0000408B1 - Process for magnetically transferring a powder image - Google Patents

Process for magnetically transferring a powder image Download PDF

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Publication number
EP0000408B1
EP0000408B1 EP78200069A EP78200069A EP0000408B1 EP 0000408 B1 EP0000408 B1 EP 0000408B1 EP 78200069 A EP78200069 A EP 78200069A EP 78200069 A EP78200069 A EP 78200069A EP 0000408 B1 EP0000408 B1 EP 0000408B1
Authority
EP
European Patent Office
Prior art keywords
powder
image
powder image
receiving support
transfer
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
Application number
EP78200069A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0000408A1 (en
Inventor
Willem Tjark Draai
Josephus Wilhelmus Rongen
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.)
Canon Production Printing Holding BV
Canon Production Printing Netherlands BV
Original Assignee
Oce Nederland BV
Oce Van der Grinten NV
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 Oce Nederland BV, Oce Van der Grinten NV filed Critical Oce Nederland BV
Publication of EP0000408A1 publication Critical patent/EP0000408A1/en
Application granted granted Critical
Publication of EP0000408B1 publication Critical patent/EP0000408B1/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G19/00—Processes using magnetic patterns; Apparatus therefor, i.e. magnetography
    • 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
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
    • G03G15/1605—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using at least one intermediate support
    • G03G15/162—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using at least one intermediate support details of the the intermediate support, e.g. chemical composition

Definitions

  • the invention relates to a process for magnetically transferring a powder image formed with the aid of permanently magnetizable powder.
  • a latent electrostatic image is formed in a photoconductive material and this image is developed with a developing powder, after which the powder image obtained is transferred to a receiving material, mostly consisting of plain paper, on which it is fixed. After the transfer of the powder image the photoconductive material is cleaned and used for a next copying run.
  • the transfer of the powder image to the receiving material is mostly effected under influence of an electric field, which is generated between the photoconductive material and the receiving material.
  • This electric transfer has the disadvantage, that blurred images occur, because powder particles are dispersed as a result of electric discharges which continuously take place in the transfer zone.
  • a further objection of the electric transfer is, that with regard to the transfer efficiency and the quality of the transferred image the results obtained with it are dependent on the atmospheric conditions and the electric properties of the developing powder and the receiving material.
  • a uniform layer of permanently magnetizable material which layer has been magnetized according to a fine linear pattern, is brought into contact with the image-carrying surface of the photoconductive material and the magnetized layer is demagnetized in those portions which are not in contact with the powder image, with the aid of a magnetic erasing head which is installed behind the photoconductive material.
  • a part of the magnetically attractable developing powder is transferred to this magnetic image.
  • the quantity of transferred developing powder is small, so that the process described cannot be applied without more as transfer method in an indirect electrophotographic copying system.
  • a further objection of this process is, that for magnetizing the permanently magnetizable layer a wide magnet head must be used, which must have been manufactured with great precision, in order to obtain a magnetic field of uniform strength over its full working width.
  • the object of the invention is to provide for an improved process for the transfer of a powder image which has been formed with the aid of a permanently magnetizable powder, in which process the powder image is magnetically transferred to a first receiving support and from the first receiving support direct or indirect to the final receiving support.
  • This process is characterized in that the transfer of the powder image to the first receiving support comprises magnetizing the powder image and bringing it into contact with a magnetizable support having a substantially uniform magnetic permeability over its whole surface and of which the magnetizable material is a soft-magnetic material having a relative magnetic permeability of at least 2.
  • the process according to the invention differs from the magnetic transfer methods known up to now, in that a high transfer efficiency is
  • the first receiving support applied in the process according to the invention has a uniform or almost uniform permeability over its whole surface, and contains soft-magnetic material which has a relative magnetic permeability of at least 2.
  • a uniform or almost uniform magnetic permeability over the whole surface of the first receiving support is necessary to prevent, that powder particles transferred to the first receiving support are moved over the surface of the support and thus disturb the image.
  • the magnetizable material in the first receiving support preferably is a soft magnetic, ferro- or ferrimagnetic material which has a relative magnetic permeability of at least 5.
  • the first receiving support may fully consist of the soft magnetic material, but it may also consist of a lowly magnetizable or non-magnetizable support on which a layer of the soft magnetic material has been applied.
  • first receiving supports are supports which consist of iron, cobalt, nickel, soft magnetic alloys of cobalt and nickel or of nickel, copper and iron, as well as supports which consist of copper, glass, aluminium, paper or plastic, on which a layer of soft magnetic material, for instance consisting of any of the above-mentioned metals or metal alloys, or of a fine dispersion of soft magnetic powder in a filmforming binding agent, has been applied with or without the aid of one or more adhesive layers.
  • the first receiving support may also consist of a self supporting plastic film in which soft magnetic powder is finely dispersed.
  • the soft magnetic material in the form of a dispersion in a filmforming binding agent
  • the soft magnetic material should have been dispersed uniformly in the binding agent, in order to obtain a uniform or almost uniform magnetic permeability over the whole surface of the first receiving support.
  • the particle size of the soft magnetic powder preferably is smaller than 1 micrometre, because with such particles the most uniform layers are obtained.
  • the weight ratio between soft magnetic powder and filmforming binding agent may amount to 3:1 to 10:1 and preferably is 5:1 to 8:1.
  • the powder image is brought into contact with the first receiving support and a magnetic field is generated in the contact zone, between the first receiving support and the material carrying the powder image, which magnetic field is sufficiently strong to magnetize the powder image.
  • the magnetized powder is kept to the first receiving support by influence.
  • the powder image can be magnetized before it is brought into contact with the first receiving support by conveying the material carrying the powder image through a magnetic field of sufficient strength.
  • this usually makes it recommendable to takes measures in order to prevent, that during the introduction in and the ejection out of the magnetizing zone the powder particles can be moved under influence of the external magnetic field, and thus cause image interferences.
  • Movement of the powder particles can for instance be prevented by pressing the powder image in and near the magnetizing zone against a diamagnetic material.
  • the powder image can also be magnetized already during the image development by applying the magnetizable powder with the aid of magnetic means, for instance a known magnetic brush developing device, on the latent image to be developed.
  • the image transferred to the first receiving support is subsequently transferred in a known way direct or indirect to the final receiving support, which will mostly consist of plain paper.
  • the direct transfer of the powder image to the final receiving support can for instance be effected in the way as described in the Dutch patent application 7209652 already mentioned, in which the final receiving support is pressed against the powder image and the image transferred as a result of the pressure- execution is subsequently fixed in a suitable way, for instance by heating, on the final receiving support.
  • the indirect transfer of the powder image to the final receiving support can for instance be executed in the way as described in British patent specification 1 245 426, in which the powder image is transferred under influence of pressure on a resilient medium and subsequently is transferred under influence of pressure and heat from the resilient medium to the final receiving support and is fixed at the same time.
  • the process according to the invention is especially attractive for application in so-called indirect electrophotographic copying systems in which for the development of the electrostatic image a permanently magnetizable developing powder, electrically conductive or not- conductive, is used.
  • the process according to the invention has the great advantage, that a good transfer of the powder image is realized under conditions which are very favourable for the duration or life of the photoconductive medium which is usually very vulnerable.
  • no heat has to be supplied to the powder image to be transferred, so that thermal charge of the photoconductive medium is prevented, only a slight contact-pressure between photoconductive medium and first receiving support is necessary, so that also the mechanical charge of the photoconductive surface is limited to a minimum.
  • the process according to the invention differs from the process as described in British patent specification 1 245 426 in a favourable way.
  • the transfer efficiency can even be increased by exposing away the electrostatic charges, which keep the powder image on the photoconductive medium, before or during the transfer.
  • the process according the invention can be applied for transferring powder images which have been formed with the aid of permanently magnetizable developing powders.
  • permanently magnetizable developing powders are known. They usually consist of thermoplastic resin particles, in which permanently magnetizable powder, for instance a powder as mentioned on page 12 of the Dutch patent application 6806473, is finely divided in a quantity which mostly lies between 30 and 70 percents by weight. Further the resin particles may also contain additions, such as colouring compounds or compounds which make the resin particles electrically conductive. These additions may have been finely divided in the resin particles or may have been deposited on the surface of the resin particles.
  • a photoconductive belt, manufactured as described in the example of British patent specification 1 408 252 was provided in a known way, by successively electrostatically charging and imagewise exposing, with a latent charge image and this charge image was developed according to the known magnetic brush method with a permanently magnetizable, one- component developing powder which had a particle size between 10 and 30 micrometres, a specific resistance of 3 x 10 8 ohm.cm and consisted of thermoplastic particles which contained 40% by weight of epoxy resin and 60% by weight of permanently magnetizable ⁇ -ferrioxide and which carried a layer of electrically conductive carbon on their surface.
  • the developing powder was prepared according to the process as described in example 3 of the Dutch patent application 7508056.
  • the image thus formed on the photoconductive belt was transferred according to the process of the invention to a receiving paper, by conveying the photoconductive belt through a transfer device having the installation as schematically represented in the figure.
  • the photoconductive belt 1, which carries the powder image 2 to be transferred is conveyed over a supporting roller 3 and with slight contact-pressure is brought into contact with an image receiving roller 4, of which the sleeve 5 consists of copper on which on the outside a layer of nickel with a thickness of about 4 micrometres has been applied.
  • the supporting roller 3 and the sleeve 5 are driven in the direction indicated by the arrows.
  • a stationary bar magnet 6 extending in axial direction is installed in such a way, that its magnet field is only effective in the nip between the roller 3 and the sleeve 5.
  • the magnet field generated in the nip has a strength of about 24 kA/m.
  • the magnet 6 achieves the magnetizing of the powder images conveyed into the nip between the roller 3 and the sleeve 5 and further serves as auxiliary magnet for the transfer of the magnetized powder image to the magnetizable sleeve 5.
  • a lamp 7 is installed just before the nip between the roller 3 and the sleeve 5, which lamp exposes away the charge image still present on the photoconductive belt 1.
  • the powder image transferred to the sleeve 5 is transferred in the nip between the sleeve 5 and the elastic pressure roller 8 under influence of pressure to a sheet of receiving paper 9 supplied from a stock pile. Finally the powder is fixed on the receiving paper by heat. Thus sharp copies of very good quality are obtained.
  • the transfer efficiency upon transferring the powder image to sleeve 5 was equal to the efficiency that was achieved with the usual electric transfer methods. Equally good results were obtained when instead of a layer of nickel the sleeve 5 was provided with a layer consisting of a fine dispersion of soft magnetic p-ferrioxide in epoxy resin in the volume ratio 1:1.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
EP78200069A 1977-07-07 1978-06-29 Process for magnetically transferring a powder image Expired EP0000408B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7707546A NL7707546A (nl) 1977-07-07 1977-07-07 Werkwijze voor het magnetisch transfereren van een poederbeeld.
NL7707546 1977-07-07

Publications (2)

Publication Number Publication Date
EP0000408A1 EP0000408A1 (en) 1979-01-24
EP0000408B1 true EP0000408B1 (en) 1981-11-25

Family

ID=19828845

Family Applications (1)

Application Number Title Priority Date Filing Date
EP78200069A Expired EP0000408B1 (en) 1977-07-07 1978-06-29 Process for magnetically transferring a powder image

Country Status (10)

Country Link
US (1) US4254206A (xx)
EP (1) EP0000408B1 (xx)
JP (1) JPS5420733A (xx)
CA (1) CA1098762A (xx)
DE (1) DE2861348D1 (xx)
DK (1) DK286578A (xx)
FR (1) FR2396993A1 (xx)
GB (1) GB2000728B (xx)
IT (1) IT7868600A0 (xx)
NL (1) NL7707546A (xx)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4536082A (en) * 1981-10-12 1985-08-20 Konishiroku Photo Industry Co., Ltd. Transfer type electrostatic reproducing apparatus
US4896662A (en) * 1987-11-30 1990-01-30 Pfizer Hospital Products Group, Inc. Sealing device for introducing cement into a bone canal
US5394226A (en) * 1991-10-16 1995-02-28 International Business Machines Corporation Method for reducing high quality electrophotographic images
KR100409245B1 (ko) * 2001-04-04 2003-12-18 박진수 무접점 다이얼장치
DE102011018607A1 (de) 2011-04-21 2012-10-25 H.C. Starck Gmbh Granulat zur Herstellung von Verbundbauteilen durch Spritzgiessen
CN117186730A (zh) 2022-05-30 2023-12-08 康宁股份有限公司 经涂覆的制品以及经涂覆的制品的制造方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3250636A (en) * 1963-01-02 1966-05-10 Xerox Corp Method and apparatus for image reproduction with the use of a reusable heat demagnetizable ferromagnetic imaging layer
GB1084285A (xx) * 1963-02-15
BE710590A (xx) * 1967-02-28 1968-06-17
GB1169510A (en) * 1968-06-21 1969-11-05 Standard Telephones Cables Ltd An Electrographic Printing Apparatus.
US3721553A (en) * 1971-04-16 1973-03-20 Rca Corp Method of transferring magnetic toner particles in an image configuration and apparatus therefor
US4051484A (en) * 1975-11-03 1977-09-27 Martin Samuel W Magnetic printer and method of performing same

Also Published As

Publication number Publication date
CA1098762A (en) 1981-04-07
JPS6321190B2 (xx) 1988-05-06
GB2000728A (en) 1979-01-17
NL7707546A (nl) 1979-01-09
FR2396993B1 (xx) 1983-09-09
DK286578A (da) 1979-01-08
DE2861348D1 (en) 1982-01-28
FR2396993A1 (fr) 1979-02-02
GB2000728B (en) 1982-01-27
IT7868600A0 (it) 1978-07-06
EP0000408A1 (en) 1979-01-24
US4254206A (en) 1981-03-03
JPS5420733A (en) 1979-02-16

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