US3863602A - Xerographic Copying Apparatus - Google Patents

Xerographic Copying Apparatus Download PDF

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Publication number
US3863602A
US3863602A US308332A US30833272A US3863602A US 3863602 A US3863602 A US 3863602A US 308332 A US308332 A US 308332A US 30833272 A US30833272 A US 30833272A US 3863602 A US3863602 A US 3863602A
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US
United States
Prior art keywords
particles
group
magazine
development unit
consist
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
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US308332A
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English (en)
Inventor
Joachim Mueller
Ludwig Dengler
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Agfa Gevaert AG
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Agfa Gevaert AG
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Publication date
Application filed by Agfa Gevaert AG filed Critical Agfa Gevaert AG
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Publication of US3863602A publication Critical patent/US3863602A/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
    • G03G15/06—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
    • G03G15/0801—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer for cascading

Definitions

  • the particle-contacting surfaces of the magazine and of all other parts which move relative to the particles (or vice versa) consist of highly conductive material and are connected to the ground.
  • the particle-contacting surfaces of the buckets and all other parts which move with the particles consist of insulating material. This allows for more accurate control of the overall charge of the mixture.
  • the present invention relates to xerographic copying apparatus in general, and more particularly to improvements in xerographic copying apparatus of the type wherein a mixture of toner particles and carrier particles is cascaded over a moving xerographic surface to convert electrostatic latent images into powder image patterns. Still more particularly, the invention relates to improvements in xerographic copying apparatus wherein the means for supplying the toner-carrier mixture preferably includes a bucket type conveyor and wherein the electrostatic charging of toner-carrier mixture takes place as a result of triboelectric effects during circulation of the mixture at the development station.
  • the mixture of toner and carrier particles is charged due to triboelectric interaction between the particles on the one hand and as a result of interaction between the particles and the particle-contacting surfaces of component parts at the development station on the other hand.
  • Such widely different interactions almost invariably cause the particles of the toner-carrier mixture to accumulate a charge which is different from the charge of the entire mixture.
  • An object of the invention is to provide a novel and improved xerographic copying apparatus wherein the triboelectric charging of the toner-carrier mixture is more homogeneous than in presently known apparatus so that the powder images which are produced in the improved apparatus exhibit a highly satisfactory contrast and the non-image areas of the xerographic surface remain free of toner.
  • the invention is embodied in a xerographic copying apparatus wherein a xerographic surface is arranged to carry electrostatic latent images along a predetermined path.
  • the copying apparatus includes a development unit which serves to convert latent images on the xerographic surface into powder image patterns and comprises a magazine for a supply of intermixed toner and carrier particles, and a conveyor which is arranged to withdraw intermixed particles from the supply in the magazine and to cascade the thus withdrawn particles over latent images on the xerographic surface whereby the surplus of particles reenters the magazine by way of a chute or analogous guide means and the particles become electrostatically charged as a result of triboelec trification during circulation in and back to the magazine.
  • the development unit has a plurality of particle-contacting surfaces (including the surfaces of the magazine and of the conveyor) which exhibit neutral characteristics with respect to the overall triboelectric charge of the supply of particles.
  • the aforementioned plurality of particle-contacting surfaces include a first group of surfaces which move with the particles (the surfaces of this first group include the particle-contacting surfaces of the conveyor) and a second group of surfaces which move relative to the particles or vice versa (the surfaces of this second group include the surface of the magazine, the surfaces of one or more chutes or analogous guide means for the particles and/0r means for agitating the particles in the magazine).
  • the surfaces of the first group preferably consist of insulating material and the surfaces of the second group preferably consist of a material which is a good conductor of electric current.
  • the surfaces of the second group are connected to the ground.
  • FIGURE is a fragmentary vertical sectional view of a xerographic copying apparatus which embodies the invention.
  • the drawing illustrates the development unit in a xerographic copying apparatus wherein the mixture of toner particles and carrier particles is cascaded over the endless xerographic surface 7 of a rotary drum 8 by a bucket type conveyor 3.
  • the buckets 5 of the conveyor 3 are filled with toner-carrier mixture during travel through a magazine 2 which contains a supply I of such mixture.
  • the other stations of the development apparatus are of conventional design and, therefore, are not shown in the drawing. They may include a charging, an exposure, a transfer and a cleaning or discharge station of the type disclosed. for example, in the commonly owned copending application Ser. No. l8l,374, filed Sept. 17, 1971 by Szostak et al.
  • the mixture I is electrostatically charged in the magazine 2 by effecting a relative movement between its particles.
  • the filled buckets 5 of the conveyor 3 travel from the lower level of the magazine 2 to a higher level, as at 4, where their contents are dumped onto a suitably inclined guide member or chute 6 for transport onto successive increments of the travelling xerographic surface 7.
  • the discharge end of the chute 6 is located downstream of the aforementioned exposure station so that the material which is discharged by successive buckets 5 onto the chute 6 is caused to come in contact with the latent image on the surface 7.
  • the mixture' of toner and carrier particles trickles along the surface 7 and thereby converts the latent image into a powder image pattern which is thereupon transferred onto discrete sheets or onto a continuous sheet at the aforementioned transfer station in a manner not forming part of the present invention.
  • the surplus toner-carrier mixture is intercepted by a guide member or chute 9 and is returned into the magazine 2 for recirculation by the conveyor 3.
  • the magazine 2 (or at least that portion of the magazine which is contacted by the particles of the supply I), at least the particle-contacting portion of the chute 6 and at least the particle-contacting portion of the intercept ing chute 9 consist of highly current-conducting material and are connected to the ground as indicated at 10. This enhances the uniformity of charges of the particles forming the supply I because, though some ofthe particles lose their charges on contact with the part 2,6 and- /or 9, they are recharged as soon as they reenter the mass of particles in the magazine.
  • the conductivity of particle-contacting portions of or entire members 6 and 9 is of advantage because the negligible discharge which takes place due to connection of members 6 and 9 with the ground is less damaging than a further charging of particles which could take place due to triboelectric interaction between the particles and the members 6 and/or 9 if the latter were not connected to ground and would not consist of conductive material.
  • the carrier particles of the supply 1 may constitute beads of glass with a coating and the particles of toner may consist of polystyrene or polyvinyl butyrol and a suitable pigment.
  • the walls of the members 2, 6 and 9 may consist of a metallic material having a specific surface conductivity in the range of lO Ohm". Alternatively, these walls may consist of brass or steel having a galvanically applied particle-contacting coating of chrome or nickel.
  • the buckets 5 of the conveyor 3 may consist of brass or steel with a coating of insulating material, such as a suitable lacquer.
  • a coating of lacquer can be applied by electrophoresis to exhibit good mechanical and insulating characteristics.
  • the buckets 5 may consist of a suitable synthetic plastic material which is a poor conductor of electric current.
  • the particle-contacting surfaces of the members 2, 5, 6 and 9 exhibit neutral characteristics with respect to the triboelectric charge of the overall mass of the mixture of carrier and toner particles. This is achieved by producing the members 2, 6 and 9 of highly current-conducting material and by connecting them with the ground. and by providing the conveyor 3 with non-conducting particle-contacting surfaces. At the same time, the thus constructed and connected members 2, 6 and 9 insure that the homogeneousness of the charge of particles forming the mixture of carrier and toner is not adversely affected by charging of particles as a result of frictional engagement with the surfaces of these members.
  • a bead of carrier material contains a relatively low charge, it cannot attract sufficient toner material for proper coating of image-bearing areas of the latent image or for attracting toner particles which tend to adhere to the non-image areas. Thus, insufficiently charged carrier beads will cause the formation of powder images with unsatisfactory contrast between imagebearing and non-image areas and with grey non-image areas.
  • unsatisfactory charging of carrier beads is prevented by making the particle-contacting surfaces of the conveyor 3 of insulating material.
  • the surfaces of parts (2,6,9) which move relative to the particles of toner and carrier material (or vice versa) conduct current and the surfaces of parts (buckets 5) which do not move relative to toner and carrier are made of insulating material. This insures that the charges cannot be dissipated and/or equalized even if the conveyor 3 is constructed and assembled to transport batches of mixture of toner and carrier beads along an elongated path, i.e., if the point 4 of discharge is remote from the supply l in the magazine 2.
  • the chute 6 and/or 9 can be dispensed with or the ground can be connected with other stationary or movable parts which come into contact with particles of the supply 1 prior to transport of particles to the discharge point.
  • Such other parts may include one or more elements of a device which is provided to agitate and/or mix the particles of carrier material and toner in the magazine 2.
  • An agitating and/or mixing device is shown diagrammatically at ll.
  • a development unit for converting said latent images into powder image patterns comprising a magazine for a supply of intermixed toner and carrier particles; and a conveyor arranged to withdraw intermixed particles from said supply and to cascade the thus withdrawn particles over latent images in said path whereby the surplus of particles reenters said magazine and the particles become electrostatically charged as a result of triboelectrification during circulation in and back to said magazine, said conveyor including a series of discrete receptacles arranged to transport batches of intermixed particles from said magazine to a level above said supply and to dump the respective batches onto said xerographic surface upon reaching said level, said development unit having a plurality of particlecontacting surfaces including the particle-contacting surfaces of said magazine and said conveyor, said plurality of surfaces exhibiting neutral characteristics with respect to the overall triboelectric charge of said supply of
  • each of said receptacles consisting of current-conducting material having a coat of insulating material so that the surfaces of said second group are provided on said coats, said second group of surfaces comprising a first chute arranged to convey particles discharged by said conveyor into said path and a second chute for intercepting surplus particles in said path and for returning the intercepted particles into said magazine.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
US308332A 1971-11-24 1972-11-21 Xerographic Copying Apparatus Expired - Lifetime US3863602A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2158334A DE2158334B2 (de) 1971-11-24 1971-11-24 Kaskadenentwicklungsvorrichtung für ein elektrostatisches Kopiergerät

Publications (1)

Publication Number Publication Date
US3863602A true US3863602A (en) 1975-02-04

Family

ID=5826033

Family Applications (1)

Application Number Title Priority Date Filing Date
US308332A Expired - Lifetime US3863602A (en) 1971-11-24 1972-11-21 Xerographic Copying Apparatus

Country Status (11)

Country Link
US (1) US3863602A (de)
JP (1) JPS5438899B2 (de)
AT (1) AT326481B (de)
BE (1) BE791113A (de)
CH (1) CH543754A (de)
DE (1) DE2158334B2 (de)
FR (1) FR2162913A5 (de)
GB (1) GB1417006A (de)
HK (1) HK54376A (de)
IT (1) IT973665B (de)
NL (1) NL7215395A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3989007A (en) * 1973-12-07 1976-11-02 U.S. Philips Corporation Developing chamber for electrostatic latent images
US4119060A (en) * 1976-07-16 1978-10-10 Ricoh Co., Ltd. Toner charging apparatus
US4231319A (en) * 1977-04-09 1980-11-04 Agfa-Gevaert, A.G. Electrostatic copying apparatus
US4288518A (en) * 1978-12-13 1981-09-08 Minolta Camera Kabushiki Kaisha Electrographic magnetic developing method

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2545951B1 (fr) * 1983-05-11 1986-11-21 Regma Procede de developpement d'une image latente formee sur une surface magnetique, dispositif pour la mise en oeuvre du procede et appareil d'impression comportant ledit dispositif
JP2517188B2 (ja) * 1991-04-16 1996-07-24 松下電器産業株式会社 電子写真方法および装置
JP2517207B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真装置
JP2517206B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真装置
JP2517203B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真装置
JP2517205B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真装置
JP2517202B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真方法
JP2517204B2 (ja) * 1993-09-07 1996-07-24 松下電器産業株式会社 電子写真装置

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303817A (en) * 1963-12-23 1967-02-14 Xerox Corp Xerographic developing apparatus
US3357399A (en) * 1966-07-21 1967-12-12 Xerox Corp Combined fluidized bed and inverted cascade development apparatus
US3527387A (en) * 1968-05-24 1970-09-08 Xerox Corp Developer replenishing programming system
US3542579A (en) * 1964-12-28 1970-11-24 Xerox Corp Electrostatic image development
US3620191A (en) * 1969-07-03 1971-11-16 Xerox Corp Biased input chute
US3641981A (en) * 1969-12-24 1972-02-15 Xerox Corp Apparatus for controlling developer charge level
US3663291A (en) * 1969-10-14 1972-05-16 Xerox Corp Cascade development
US3674532A (en) * 1970-07-23 1972-07-04 Eastman Kodak Co Control for bias of magnetic brush and method
US3682538A (en) * 1970-03-19 1972-08-08 Xerox Corp Xerographic pick-off plate

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303817A (en) * 1963-12-23 1967-02-14 Xerox Corp Xerographic developing apparatus
US3542579A (en) * 1964-12-28 1970-11-24 Xerox Corp Electrostatic image development
US3357399A (en) * 1966-07-21 1967-12-12 Xerox Corp Combined fluidized bed and inverted cascade development apparatus
US3527387A (en) * 1968-05-24 1970-09-08 Xerox Corp Developer replenishing programming system
US3620191A (en) * 1969-07-03 1971-11-16 Xerox Corp Biased input chute
US3663291A (en) * 1969-10-14 1972-05-16 Xerox Corp Cascade development
US3641981A (en) * 1969-12-24 1972-02-15 Xerox Corp Apparatus for controlling developer charge level
US3682538A (en) * 1970-03-19 1972-08-08 Xerox Corp Xerographic pick-off plate
US3674532A (en) * 1970-07-23 1972-07-04 Eastman Kodak Co Control for bias of magnetic brush and method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3989007A (en) * 1973-12-07 1976-11-02 U.S. Philips Corporation Developing chamber for electrostatic latent images
US4119060A (en) * 1976-07-16 1978-10-10 Ricoh Co., Ltd. Toner charging apparatus
US4231319A (en) * 1977-04-09 1980-11-04 Agfa-Gevaert, A.G. Electrostatic copying apparatus
US4288518A (en) * 1978-12-13 1981-09-08 Minolta Camera Kabushiki Kaisha Electrographic magnetic developing method

Also Published As

Publication number Publication date
DE2158334A1 (de) 1973-05-30
CH543754A (de) 1973-10-31
AT326481B (de) 1975-12-10
IT973665B (it) 1974-06-10
BE791113A (nl) 1973-05-09
DE2158334B2 (de) 1980-04-24
GB1417006A (en) 1975-12-10
ATA751072A (de) 1975-02-15
JPS4868237A (de) 1973-09-18
JPS5438899B2 (de) 1979-11-24
FR2162913A5 (de) 1973-07-20
HK54376A (en) 1976-09-10
NL7215395A (de) 1973-04-25

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