US3872828A - Xerographic copying apparatus with intercepting means for carrier particles - Google Patents

Xerographic copying apparatus with intercepting means for carrier particles Download PDF

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Publication number
US3872828A
US3872828A US315482A US31548272A US3872828A US 3872828 A US3872828 A US 3872828A US 315482 A US315482 A US 315482A US 31548272 A US31548272 A US 31548272A US 3872828 A US3872828 A US 3872828A
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United States
Prior art keywords
carrier particles
xerographic
xerographic surface
intercepting
particles
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Expired - Lifetime
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US315482A
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English (en)
Inventor
Karl Hartwig
Juergen Vossnacke
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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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    • 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

  • ABSTRACT A xerographic copying apparatus wherein a cylindrical xerographic surface travels past a development unit wherein a bucket conveyor draws batches of charged toner particles and spherical carrier particles from a magazine and dumps the withdrawn particles onto the xerographic surface so that the toner particles adhere to and convert electrostatic latent images into powder images.
  • the carrier particles descend along the xerographic surface and are intercepted and returned into the magazine by an elastic strip which extends radially of the xerographic surface and defines therewith a clearance whose width is a fraction of the diameters of carrier particles. Those carrier particles which strongly adhere to the xerographic surface deform and are thus free to bypass the elastic strip.
  • the invention relates to xerographic copying apparatus and more particularly to improvements in xerographic copying apparatus wherein a mixture of toner particles and carrier particles is cascaded over a moving xerographic surface to effect the conversion of electrostatic latent images into powder images which are ready to be transferred onto paper sheets or the like. Still more particularly, the invention relates to improvements in means for intercepting toner and/or carrier particles during or subsequent to conversion of latent images into powder images.
  • Such intercepting device comprises a rigid blade-like member which makes an acute angle with the adjacent portion of the xerographic surface and acts as a means for returning carrier particles into a magazine from which a bucket conveyor or an analogous transporting device withdraws batches of tonercarrier mixture for delivery to a location where the contents of the buckets are dumped onto the moving xerographic surface.
  • a drawback of such intercepting devices is that the carrier particles (such as small spheres or beads) are likely to jam between the rigid blade-like member and the xerographic surface, especially if the carrier particles advance toward the bladelike member in the direction in which the xerographic surface travels at and beyond the development station. This can result in damage to the highly sensitive xerographic surface or in substantial losses in carrier material if the gap between the xerographic surface and the I blade-like member is wide enough to allow the carrier particles to pass therethrough without jamming.
  • the carrier particles such as small spheres or beads
  • An object of the invention is to provide a xerographic copying apparatus with novel and improved means for intercepting all or nearly all particles of developer material, especially carrier particles, in such a way that the intercepting means and/or'the intercepted particles are not likely to damage the xerographic surface.
  • Another object of the invention is to provide intercepting means which can be readily and conveniently adjusted to normally collect all particles of surplus developer material, even if the dimensions of such particles vary within a wide range.
  • a further object of the invention is to provide a xerographic copying apparatus with a novel development unit which embodies the improved intercepting means.
  • An additional object of the invention is to provide intercepting means which can be installed in existing types of xerographic copying apparatus.
  • the invention is embodied in a xerographic copying apparatus wherein a preferably cylindrical xerographic surface transports electrostatic latent images.
  • the copying apparatus comprises a development unit having a magazine for a supply of intermixed toner particles and preferably spherical carrier particles, conveyor means for removing toner and carrier particles from the supply in the magazine and for dumping the thus removed particles onto the xerographic surface whereby at least some toner particles adhere to the xerographic surface and convert the latent images into powder images and the carrier particles descend by gravity along and some thereof adhere to the xerographic surface, and novel intercepting means for returning at least some of the carrier particles into the magazine.
  • the intercepting means comprises at least one intercepting element having a preferably thin stripshaped elastically deformable portion extending close to .but being spaced apart from the xerographic surface.
  • the width of the clearance between the intercepting element and the xerographic surface is preferably only a fraction of the diameters of carrier particles so that the intercepting element can remove all or nearly all carrier particles which adhere to the xerographic surface. Those carrier particles which adhere to the surface with a predetermined force deform and are thus free to bypass the intercepting element.
  • FIG. 1 is a fragmentary vertical sectional view of a xerographic copying apparatus which embodies the improved intercepting means fortoner and/or carrier particles;
  • FIG. 2 is an enlarged view of the detail within the phantom-line circle A in FIG. 1.
  • FIG. l illustrates a portion of a xerographic copying apparatus which comprises an endless xerographic surface 7 applied to the periphery of a rotary drum 8 and serving to transport electrostatic latent images past a development unit including a magazine 15 the lower portion of which contains a supply 16 of a mixture 1 of toner and carrier particles.
  • the carrier particle s la resemble globules or beads.
  • An endless conveyor having a chain or belt 2 for a series of receptacles in the form of pivotable buckets 3 serves to transport batches of carrier-toner mixture 1 from the supply 16 to a dumping station 17 where the filled buckets 3 are tilted sufficiently to discharge their contents onto the xerographic surface 7 which is assumed to travel in the direction indicated by arrow 8
  • the endless chain or belt 2 of the conveyor is trained over several sprocket wheels or pultoner adhere to the image areas of the xerographic surface 7 in order to convert the latent image into a powder image pattern which is thereupon transferred onto sheet material in a manner well known from the art and not shown in the drawing.
  • the carrier particles la which are dumped at the station 17 descend by gravity by moving with and/or relative to the xerographic surface 7 (arrow 8) and are returned into the lower portion of the magazine by a novel intercepting device which includes two discrete units each of which can direct carrier particles In into the supply 16 so that the carrier particles can accumulate fresh toner particles prior to entering an oncoming bucket 3 for renewed transport to the dumping station 17.
  • the upper unit of the intercepting device comprises a chute 9 of sheet metal or the like which extends substantially radially of the drum 8 and slopes downwardly to the extent which is necessary to insure that the carrier particles 1a descending onto its upper side can roll back into the supply 16.
  • the right-hand end portion or edge portion 9a of the chute 9 is curved upwardly and is spaced apart from the xerographic surface 7, i.e., the parts 7 and 9a define a gap which is substantially parallel to the axis of the drum 8 and is wide enough to allow practically or completely unobstructed passage of all such carrier particles 1a which adhere to the surface 7 at the time they reach the edge portion 9a.
  • Those carrier particles 1a which adhere to the xerographic surface 7 and advance therewith beyond the edge portion 9a normally constitute a relatively small fraction of the overall number of carrier particles la which are dumped onto the surface 7 at the station 17.
  • the second unit ofthe intercepting device comprises a support 10 which may consist of sheet metal and may form an integral or removable part of the magazine 15.
  • This support is adjacent to but spaced apart from the xerographic surface 7 below the chute 9 and carries a substantially plate-like holder 11 which is adjustably secured thereto by one or more screws 13 or analogous fasteners so that it can be moved in directions indicated by a doubleheaded arrow 11.
  • the holder 11 may be provided with elongated slots, one for each fastener 13 and each extending substantially radially of the drum 8 so that, when the fasteners 13 are loose, the holder 11 can be shifted radially toward or away from the drum 8.
  • the holder 11 serves as a base for a relatively thin, flexible and preferably elastic strip 12 which may consist of elastomeric synthetic plastic material and the underside of which may be glued or otherwise permanently or detachably secured to the upper side of the holder 11.
  • the strip 12 (which constitutes a particle-removing element in the form of a blade or the like) has a portion 12 a which extends beyond the edge face 100 of the support 10 and the edge face 110 of the holder 11 toward the xerographic surface 7 and is sufficiently flexible to allow for the passage of those carrier particles 1a which adhere to the surface 7 with a predetermined force such as is likely to result in damage to the surface 7 if the strongly adhering carrier particles were stripped off by the element 12.
  • the length of the unsupported portion 12a of the element 12 (as considered in the radial direction of the drum 8) is shown at 1, and such length may be in the range of a few millimeters.
  • the major percentage of carrier particles In which are dumped onto the surface 7 at the station 17 will descend onto the chute 9 and will be automatically returned into the lower part of the magazine 15.
  • the edge face of the portion should not contact the xerographic surface 7 because this could adversely affect the xerographic copying operation, for example, by removing toner from the powder image which is being transported toward the transfer station of the copying apparatus.
  • the portion 12a of the element 12 should separate from the xerographic surface 7 at least those carrier particles 1a which do not adhere with a substantial force. Therefore, the distance or clearance r between the surface 7 and the portion 12a of the element 12 is selected in such a way that it is between onetenth and one-half the diameter of smallest carrier particles 1a which are employed in the copying apparatus. For example, if the diameters of carrier particles la range between 0.6 and 0.8 millimeter, the distance or clearance rmay be in the range of0.l to 0.3 millimeter, preferably between 0.2 and 0.25 millimeter. It has been found that the last-mentioned range is particularly satisfactory to insure the retrieval of all loosely adhering carrier particles la.
  • the mixture 1 which forms the supply 16 in the lower part of the magazine 15 contains carrier particles la whose diameters deviate from the diameters of the majority of carrier particles.
  • some of the carrier particles 1a may be so small that they can readily escape through the clearance r even if the width of this clearance is selected with a view to invariably intercept all loosely adhering carrier particles having known diameters.
  • the attendant or attendants fail to properly select the width of the clearance r so that at least some of the carrier particles 1a (including those which do not adhere to the xerographic surface 7 with a substantial force) will bypass the portion 12a and will not be returned into the magazine 15. This can be readily remedied byadjusting the holder 11 relative to the support 10 so as to reduce the width of the clearance r.
  • the elasticity of the portion 12a of the element 12 guarantees that the portion 120 is capable of yielding to such strongly adhering carrier particles 1a whereby the carrier particles advance beyond the mag azine 15 and can be collected in a separate receptacle (not shown) downstream of the development unit or are separated from the surface 7 in another suitable way not forming part of the present invention.
  • the direction in which the unsupported portion 12a of the element 12 can yield when engaged by one or more carrier particles 1a which adhere to the xerographic surface with a predetermined force is indicated by the arrow 12.
  • An important advantage of the improved intercepting device is that, if properly adjusted, the elastically deformable element 12 invariably segregates from the xerographic surface 7 all such carrier particles 10 which can be removed without causing damage to the surface 7 so that the operation of the development unit is economical without, however, economizing to such an extent that the retrieval of carrier particles 1a would be promoted at the risk of damaging the surface 7.
  • the chute 9 (which constitutes an optional feature of the intercepting device) relieves the second unit including the element 12, i.e., the chute 9 normally intercepts the majority of carrier particles la so that the carrier particles which advance toward and are engaged by the portion 12a include only those which cannot be separated from the surface 7 by gravity and/or by centrifugal force.
  • the holder 11 can be provided with or can be moved relative to a scale which enables the operator to properly select the width of the clearance r for separation of all or nearly all carrier particles with the excepv tion of those whose separation would result or would be likely to result in damage to the xerographic surface 7.
  • the exact composition of the material of the element 12 forms no part of this invention; this element may consist of any material which exhibits sufficient elasticity to yield to carrier particles la adhering to the surface 7 with a force which, if overcome by the element 12, would be likely to bring about damage to the surface 7.
  • the inclination of the element 12 relative to the drum 8 can be varied within a wide range; it was found that an elastic element which extends substantially radially of the drum 8 is capable of intercepting all or nearly all carrier particles 1a which move beyond the chute 9 (with the exception of those particles which adhere to the xerographic surface 7 with a force exceeding a predetermined force).
  • a development unit including a magazine for a supply of intermixed toner and substantially spherical carrier particles, conveyor means for removing toner and carrier particles from the supply in said magazine and for dumping the thus removed particles onto said xerographic surface at a first level whereby at least some toner particles adhere to said xerographic surface to convert said latent images into powder images and the carrier particles descend by gravity along and some thereof adhere to said xerographic surface, and intercepting means for returning at least some of the dumped carrier particles into said magazine, said intercepting means comprising an intercepting element extending substantially radially of said xerographic surface and having an elastically deformable substantially strip-shaped portion extending close to but being spaced apart from said xerographic surface at a second level below said first level, said deformable portion-of said intercepting element having an elongated edge defining with said xerographic surface a clearance whose width

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Cleaning In Electrography (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
US315482A 1971-12-17 1972-12-15 Xerographic copying apparatus with intercepting means for carrier particles Expired - Lifetime US3872828A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2162842A DE2162842C3 (de) 1971-12-17 1971-12-17 Kaskadenentwicklungsvorrichtung für ein elektrostatisches Kopiergerät

Publications (1)

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US3872828A true US3872828A (en) 1975-03-25

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US315482A Expired - Lifetime US3872828A (en) 1971-12-17 1972-12-15 Xerographic copying apparatus with intercepting means for carrier particles

Country Status (8)

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US (1) US3872828A (enrdf_load_stackoverflow)
JP (1) JPS5131654Y2 (enrdf_load_stackoverflow)
BE (1) BE792331A (enrdf_load_stackoverflow)
DE (1) DE2162842C3 (enrdf_load_stackoverflow)
FR (1) FR2165455A7 (enrdf_load_stackoverflow)
GB (1) GB1420971A (enrdf_load_stackoverflow)
IT (1) IT974069B (enrdf_load_stackoverflow)
NL (1) NL7216926A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040386A (en) * 1975-05-01 1977-08-09 Xerox Corporation Retractable edge seals for electrostatographic development systems
US4194465A (en) * 1977-02-24 1980-03-25 Fuji Xerox Co., Ltd. Magnetic brush developer device
US4571060A (en) * 1984-10-22 1986-02-18 Xerox Corporation Housing seal

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5937831B2 (ja) * 1975-01-21 1984-09-12 キヤノン株式会社 電子写真現像装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356067A (en) * 1966-09-14 1967-12-05 Lodding Engineering Corp Doctor blades having relieved ends
US3424131A (en) * 1964-09-30 1969-01-28 Xerox Corp Electroded cascade development system
US3430606A (en) * 1968-01-02 1969-03-04 Xerox Corp Electroscopic particle sensor
US3634077A (en) * 1968-08-26 1972-01-11 Xerox Corp Method and apparatus for removing a residual image in an electrostatic copying system
US3678896A (en) * 1971-01-28 1972-07-25 Xerox Corp Conveyor system
US3695224A (en) * 1971-11-26 1972-10-03 Stephen F Royka Cascade development
US3696784A (en) * 1970-12-15 1972-10-10 Xerox Corp Xerographic development apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3424131A (en) * 1964-09-30 1969-01-28 Xerox Corp Electroded cascade development system
US3356067A (en) * 1966-09-14 1967-12-05 Lodding Engineering Corp Doctor blades having relieved ends
US3430606A (en) * 1968-01-02 1969-03-04 Xerox Corp Electroscopic particle sensor
US3634077A (en) * 1968-08-26 1972-01-11 Xerox Corp Method and apparatus for removing a residual image in an electrostatic copying system
US3696784A (en) * 1970-12-15 1972-10-10 Xerox Corp Xerographic development apparatus
US3678896A (en) * 1971-01-28 1972-07-25 Xerox Corp Conveyor system
US3695224A (en) * 1971-11-26 1972-10-03 Stephen F Royka Cascade development

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040386A (en) * 1975-05-01 1977-08-09 Xerox Corporation Retractable edge seals for electrostatographic development systems
US4194465A (en) * 1977-02-24 1980-03-25 Fuji Xerox Co., Ltd. Magnetic brush developer device
US4571060A (en) * 1984-10-22 1986-02-18 Xerox Corporation Housing seal

Also Published As

Publication number Publication date
FR2165455A7 (enrdf_load_stackoverflow) 1973-08-03
DE2162842B2 (de) 1980-06-12
NL7216926A (enrdf_load_stackoverflow) 1973-05-25
DE2162842C3 (de) 1981-06-11
IT974069B (it) 1974-06-20
JPS5131654Y2 (enrdf_load_stackoverflow) 1976-08-07
BE792331A (fr) 1973-06-06
GB1420971A (en) 1976-01-14
DE2162842A1 (de) 1973-06-20
JPS4874058U (enrdf_load_stackoverflow) 1973-09-14

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