US3521126A - Roller charging apparatus - Google Patents

Roller charging apparatus Download PDF

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Publication number
US3521126A
US3521126A US656820A US3521126DA US3521126A US 3521126 A US3521126 A US 3521126A US 656820 A US656820 A US 656820A US 3521126D A US3521126D A US 3521126DA US 3521126 A US3521126 A US 3521126A
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United States
Prior art keywords
roller
ceramic
resistivity
rollers
charging apparatus
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Expired - Lifetime
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US656820A
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English (en)
Inventor
Daniel B Granzow
Karl K Klessig
Richard J Pleitt
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AB Dick Co
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Multigraphics Inc
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Publication date
Application filed by Multigraphics Inc filed Critical Multigraphics Inc
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Publication of US3521126A publication Critical patent/US3521126A/en
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    • 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
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
    • G03G15/0208—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices by contact, friction or induction, e.g. liquid charging apparatus
    • G03G15/0216—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices by contact, friction or induction, e.g. liquid charging apparatus by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers
    • G03G15/0233—Structure, details of the charging member, e.g. chemical composition, surface properties

Definitions

  • This material comprises a major portion of aluminum oxide or baryllium oxideand a minor portion of a reducible metal ion containing additive, such as iron oxide, tin oxide, copper oxide, zinc oxide, manganese oxide or silicon carbide.
  • a reducible metal ion containing additive such as iron oxide, tin oxide, copper oxide, zinc oxide, manganese oxide or silicon carbide.
  • Reduction of the additive provides the metal particles which are present in an amount sucient to render the material semi-conductive so that its resistivity is in the range of from about lOl-109 ohm-centimeters as measured over an applied voltage within the range of from 2-8 kilovolts.
  • This invention relates to improvements in conventional roller 'charging apparatus, and more particularly concerns a roller charging apparatus employing a novel semi-conductive ceramic roller electrode.
  • roller charging devices are well known means for uniformly charging a photoelectrostatic recording member.
  • These conventional roller charging devicesy include a pair of driven roller electrodes connected to a DC power supply.
  • One of the rollers of the apparatus is formed of a semi-conductive material, such as rubber or a ceramic, mounted on a conductive shaft.
  • the other is made of a highly conductive material such as, for example, metal.
  • the rubber roller although initially functioning in a satisfactory manner, breaks down and becomes either conductive or highly resistive within a few hours operating time under the influence of the ionized and ozone laden atmosphere in the vicinity of the charging apparatus. If the resistivity of the rubber decreases below about 106 ohm-centimeters, it is considered too conductive. Whereas, if its resistivity exceeds 1010 ohm-centimeters, it is considered too resistive. As a result, the apparatus is no longer able to charge the photoelectrostatic recording member in a satisfactory manner.
  • known ceramic rollers although they do not usually undergo degradation in electrical properties to the degree exhibited by rubber rollers, are also generally too conductive or too resistive. Charging apparatus using such conventional ceramic rollers are incapable of laying down on the surface of the recording member a charge of a high enough voltage level. As a result, the photoelectrostatic recording member may not be imagable or the density of the image is very poor. Due to these disadvantages, known roller charging devices have not been used in commercial photoelectrostatic copying equipment.
  • the improved roller charging apparatus of this invention is equipped with a pair of driven roller electrodes for charging the member and moving it along a predetermined path, and power supply means connected to the roller electrodes for establishing an electric iield therebetween which ionizes the atmosphere between and about the nip of the roller electrodes.
  • the improvement is that one of the roller electrodes is formed of a ceramic material having a resistivity within the' range of from about 107 to 109 ohm-centimeters as measured over an applied voltage with the range of from 2-8 kilovolts.
  • the resistivity of the ceramic material employed must be within the above mentioned resistivity range. This limitation is critical.
  • a preferred form of ceramic material commonly referred to in ceramic art as a cermet, has randomly shaped sub-micron size metallic particles distributed throughout in an amount suilicient to render said ceramic semi-conductive so that its resistivity is within the aforesaid critical range.
  • One type of cermet which can be used comprises a major amount of aluminum oxide or beryllium oxide and a minor amount of metal ion containing additive that can readily be reduced to provide the metallic particles.
  • Additives, such as iron oxide, tin oxide, copper oxide, zinc oxide, manganese oxide and silicon carbide have been found to be most suitable. These additives are preferably present in an amount of from about 10%-25% by weight of the material.
  • a readily reducible additive or mixture of additives such as already mentioned, are admixed with the major constituent and reduced until a sufficient amount of elemental metallic material is available so that the resistivity of the ceramic is within the prescribed range.
  • free metallic particles may be added to the ceramic during preparation, this method is usually not preferred because it is extremely difficult to control the resistivity with any degree of consistencey. However, the addition of a trace amount of a free metal, such as, for example, manganese, may be beneficial.
  • FIG. 1 is an elevational view partially in section of the preferred embodiment of this invention.
  • FIG. 2 is a sectional view taken along line 2-2 of FIG. l.
  • the improved roller charging apparatus of this invention is provided with a roller electrode 12 having a novel ceramic shell 14.
  • the ceramic shell material has a resistivity within the range of from about 10'-109 ohm-centimeters as measured over an applied voltage ranging from 2-8 kilovolts.
  • the preferred resistivity is about 108 ohm-centimeters as measured at about 5 kilovolts. It will be appreciated that the measured resistivity of the ceramic material, in addition to being a property of the material per se, is also dependent on the applied voltage at which the measurement is taken. Accordingly, the resistivity is measured over an applied voltage ranging from 2-8 kilovolts.
  • a sample of known crosssectional area and length is connected lengthwise between the positive and negative terminals of a power supply having a known output voltage in the range of from 2-8 kilovolts.
  • a current meter is also connected across the sample so that current flow through the length of the sample is measured. The resistivity is then calculated using the following formula:
  • A the cross-sectional area of the sample in square centimeters
  • V the applied voltage
  • Resstivity measurements are taken at about 72 F.
  • a wide variety of materials can be used in the preparation of the ceramic shell 14, but care must be taken to insure the resistivity of the ceramic material is within the critical range.
  • a major portion of a ceramic such as, for example, aluminum oxide and a minor portion of an additive such as, for example, iron oxide, are blended together with a small amount of water to form a paste.
  • the paste is sprayed dry to 4form a fine powder which is then placed in a mold and packed down by applying from both ends of the mold a pressure of about 10,000 pounds per square inch.
  • the shell is then removed from the mold and baked for several hours (approximately 8 hours) in a reducing environment such as an atmosphere containing hydrogen. During the baking or firing process the temperature is gradually increased to about 1000 C., maintained at this level for a given period and then gradually reduced.
  • This control baking process regulates the degree to which the additive is reduced.
  • the tiring period, temperature, and rate of heating and cooling are varied depending on the material used in order to produce a ceramic having the proper resistivity.
  • the iron oxide is, as a result of the firing, partially reduced to provide submicron size metal particles, which are schematically i1- lustrated in FIG. 1v as 13. Although it is believed that the aluminum oxide is not reduced, it is possible that this material is partially reduced during the firing process to provide trace amounts of free aluminum metal.
  • additives such as, for example, copper oxide, tin oxide., zinc oxide, manganese oxide and silicon carbide, or mixtures thereof, can be used.
  • charging apparatus employing a ceramic roller having a resistivity in the range of from about 1 l08 to 3 l08 ohm-centimeters as measured at about 5 kilovolts can feed a photoelectrostatic member at varying rates anywhere from about 0-40 feet per minute and still lay down a charge having the same voltage level (approximately 600 volts), regardless of the speed the member is being moved. Accordingly, ceramic rollers of this resistivity are preferred.
  • roller charging apparatus 10 including roller 12 and a metal idler roller 16.
  • Rollers 12 and 16 are mounted in driving engagement between sidewalls 18 and 20, with roller 16 being held by brackets 22 and 24.
  • This roller 16 can have the same or a different size diameter than roller 12, and more than one such metal idler roller can be in driving engagement with roller 12.
  • Roller 12 is mounted on a conductive drive shaft 34 which makes electrical contact along substantially the entire length of the roller, thereby insuring the establishment of an effective corona charging zone between and about the nip of rollers 12 and 16.
  • Shaft 34 is received in non-conductive bearings 30 and 32 which are supported in the sidewalls 18 and 20.
  • a pulley 40 mounted by means of an insulating bushing 42 and driven by motor 44, is connected to one end of shaft 34. When the motor 44 is turned on, the rollers 12 and 16 are driven.
  • Other drive arrangements too numerous to describe in detail, can be employed which are equivalent to the structure set forth and are contemplated to be within the scope of this invention.
  • a brush member 46 engaging the other end of shaft 34 is connected to the negative terminal of a 5kilovolt DC power supply 48.
  • the metal idler roller 16 is connected to ground so that the potential between the rollers 12 and 16 is about 5 kilovolts.
  • An improved charging apparatus of the type that applies a uniform electrostatic charge to the surface of a photoelectrostatic recording member, said apparatus having a pair of driven roller electrodes for charging the member and moving it along a predetermined path, and power supply means connected to said roller electrodes for ionizing the atmosphere between and about the nip of the rollers, the improvement wherein one of the roller electrodes comprises a ceramic material having a resistance within the range of from about 10FI to 109 ohm-centimeters as measured over an applied voltage within the range of 2-8 kilovolts, wherein said ceramic material contains sub-micron size elemental metallic particles which are uniformly distributed throughout, and wherein a major amount of said ceramic material is selected from the group consisting of aluminum oxide and beryllium oxide, and a minor amount of an additive containing a reducible metal cation selected from the group consisting of iron, tin, copper, zinc, manganese and silicon, said additive being partially reduced to render said metal cation reduced to its elemental form.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Delivering By Means Of Belts And Rollers (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Rolls And Other Rotary Bodies (AREA)
US656820A 1967-07-28 1967-07-28 Roller charging apparatus Expired - Lifetime US3521126A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US65682067A 1967-07-28 1967-07-28

Publications (1)

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US3521126A true US3521126A (en) 1970-07-21

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Application Number Title Priority Date Filing Date
US656820A Expired - Lifetime US3521126A (en) 1967-07-28 1967-07-28 Roller charging apparatus

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US (1) US3521126A (enrdf_load_stackoverflow)
BE (1) BE718180A (enrdf_load_stackoverflow)
GB (1) GB1228987A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3626260A (en) * 1968-03-19 1971-12-07 Iwatsu Electric Co Ltd Method and apparatus for applying voltage in electrophotography
US3697836A (en) * 1970-06-03 1972-10-10 Coors Porcelain Co Ceramic electrical resistor roll for copying machine
US3787706A (en) * 1970-05-04 1974-01-22 Agfa Gevaert Nv Apparatus for the control of charge on a moving web
US4079437A (en) * 1976-04-30 1978-03-14 Minnesota Mining And Manufacturing Machine and method for poling films of pyroelectric and piezoelectric material
US4089034A (en) * 1976-04-30 1978-05-09 Minnesota Mining And Manufacturing Company Machine and method for poling films of pyroelectric and piezoelectric material
EP0387815A3 (en) * 1989-03-14 1992-05-13 Canon Kabushiki Kaisha Charging member and electrophotographic apparatus using the same
WO1994011791A1 (en) * 1992-11-09 1994-05-26 American Roller Company Charge donor roller with blended ceramic layer
US5408070A (en) * 1992-11-09 1995-04-18 American Roller Company Ceramic heater roller with thermal regulating layer
USRE35698E (en) * 1992-10-02 1997-12-23 Xerox Corporation Donor roll for scavengeless development in a xerographic apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ192629A (en) 1979-02-05 1983-05-31 British Cellophane Ltd Treating plastics film by corona discharge electrodes constructed and spaced to prevent arc discharges
DE3164262D1 (en) * 1980-03-10 1984-07-26 Tokyo Shibaura Electric Co Charging device
US6238759B1 (en) * 1999-05-25 2001-05-29 Lexmark International, Inc. Coated charge roller

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2975145A (en) * 1958-04-16 1961-03-14 Bendix Corp Semi-conductive ceramic composition
US2980834A (en) * 1956-04-26 1961-04-18 Bruning Charles Co Inc Charging of photo-conductive insulating material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980834A (en) * 1956-04-26 1961-04-18 Bruning Charles Co Inc Charging of photo-conductive insulating material
US2975145A (en) * 1958-04-16 1961-03-14 Bendix Corp Semi-conductive ceramic composition

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3626260A (en) * 1968-03-19 1971-12-07 Iwatsu Electric Co Ltd Method and apparatus for applying voltage in electrophotography
US3787706A (en) * 1970-05-04 1974-01-22 Agfa Gevaert Nv Apparatus for the control of charge on a moving web
US3697836A (en) * 1970-06-03 1972-10-10 Coors Porcelain Co Ceramic electrical resistor roll for copying machine
US4079437A (en) * 1976-04-30 1978-03-14 Minnesota Mining And Manufacturing Machine and method for poling films of pyroelectric and piezoelectric material
US4089034A (en) * 1976-04-30 1978-05-09 Minnesota Mining And Manufacturing Company Machine and method for poling films of pyroelectric and piezoelectric material
EP0387815A3 (en) * 1989-03-14 1992-05-13 Canon Kabushiki Kaisha Charging member and electrophotographic apparatus using the same
US6041209A (en) * 1989-03-14 2000-03-21 Canon Kabushiki Kaisha Charging member having an elastomeric member including an elastomeric material having a double oxide
US5757508A (en) * 1989-03-14 1998-05-26 Canon Kabushiki Kaisha Charging member having an elastomeric member comprising an elastomeric material and a double oxide
USRE35698E (en) * 1992-10-02 1997-12-23 Xerox Corporation Donor roll for scavengeless development in a xerographic apparatus
US5600414A (en) * 1992-11-09 1997-02-04 American Roller Company Charging roller with blended ceramic layer
US5707326A (en) * 1992-11-09 1998-01-13 American Roller Company Charging roller with blended ceramic layer
US5408070A (en) * 1992-11-09 1995-04-18 American Roller Company Ceramic heater roller with thermal regulating layer
WO1994011791A1 (en) * 1992-11-09 1994-05-26 American Roller Company Charge donor roller with blended ceramic layer
JP3426227B2 (ja) 1992-11-09 2003-07-14 アメリカン ローラ カンパニー，エルエルシー 混合セラミックス層を有する帯電ローラの製造方法
JP3425950B2 (ja) 1992-11-09 2003-07-14 アメリカン ローラ カンパニー，エルエルシー 混合セラミック層を有する電荷ドナーローラ

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Publication number Publication date
GB1228987A (enrdf_load_stackoverflow) 1971-04-21
BE718180A (enrdf_load_stackoverflow) 1968-12-31

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