CA1184591A - Magnetic brush cleaning system - Google Patents
Magnetic brush cleaning systemInfo
- Publication number
- CA1184591A CA1184591A CA000371911A CA371911A CA1184591A CA 1184591 A CA1184591 A CA 1184591A CA 000371911 A CA000371911 A CA 000371911A CA 371911 A CA371911 A CA 371911A CA 1184591 A CA1184591 A CA 1184591A
- Authority
- CA
- Canada
- Prior art keywords
- roller
- magnitude
- printing machine
- particles
- polarity
- 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
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
- G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium
- G03G21/0047—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium using electrostatic or magnetic means; Details thereof, e.g. magnetic pole arrangement of magnetic devices
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2221/00—Processes not provided for by group G03G2215/00, e.g. cleaning or residual charge elimination
- G03G2221/0005—Cleaning of residual toner
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Cleaning In Electrography (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
- Cleaning In General (AREA)
Abstract
ABSTRACT
An electrophotographic printing machine which has a cleaning station for removing particles from a photoconductive surface. The cleaning station includes a magnetic transport for moving a cleaning material into contact with the photoconductive surface. The magnetic transport is electrically biased to a polarity and magnitude sufficient to attract the particles from the photoconductive surface to the cleaning material.
An electrically non-conductive member, positioned close-ly adjacent to the magnetic transport, is electrically biased to the same polarity as the magnetic transport with the magnitude thereof being greater than the magnitude of the electrical bias applied to the magnetic transport. In this way, particles adhering to the cleaning material on the magnetic transport are attracted therefrom to the electrically non-conductive member.
An electrophotographic printing machine which has a cleaning station for removing particles from a photoconductive surface. The cleaning station includes a magnetic transport for moving a cleaning material into contact with the photoconductive surface. The magnetic transport is electrically biased to a polarity and magnitude sufficient to attract the particles from the photoconductive surface to the cleaning material.
An electrically non-conductive member, positioned close-ly adjacent to the magnetic transport, is electrically biased to the same polarity as the magnetic transport with the magnitude thereof being greater than the magnitude of the electrical bias applied to the magnetic transport. In this way, particles adhering to the cleaning material on the magnetic transport are attracted therefrom to the electrically non-conductive member.
Description
A MAGNETIC BRUSH CLEANING SYSTEM
This invention relates generally to an elec-trophotographic printing machine, and more particularly concerns an improved cleaning system for use therein.
In electrophotographic printing, a photocon-ductive member is charged to sensitize the surface thereof. The charged photoconductive member is exposed to a light image of an original document being repro-lQ duced. Exposure of the sensitized photoconductivesurface discharges the charge selectively. This re-cords an electrostatic latent image on the photoconduc-tive surface corresponding to the informational areas contained within the original document being reproduced.
Development of the electrostatic latent image recorded on the photoconductive surface is achieved by bringing a developer material into contact therewith. Typical developer materials comprise a heat settable plastic powder, known in the art as toner particles, which adhere triboelectrically to coarser magnetic carrier granules, such as ferromagnetic granules~ The toner particles are selected to have the appropriate charge relative to the electrostatic latent image recorded on the photoconductive surface. When the developer 2S material is brought into contact with the latent image recorded on the photoconductive surrace, a greater attractive force thereof causes the toner particles to transfer from the carrier granules to the electro-static latent image.
Frequently, residual toner particles remain adhering to the photoconductive surface after the transfer thereof to the sheet of support material.
Hereinbefore, ordinary cleaning devices such as brushes or foam rollers, have not been entirely satisfactory in cleaning residual part~cles from the photoconduc-tive surface. One of the more attractive methods for cleaning particles from the photoconductive surface has been to use a rotating magnet enclosed in a sta-tionary, non-magnetic shell. This system attracts carrier granules which, in turn, attract triboelectri-cally the residual toner particles from the photocon-ductive surface. One of the problems assiciated with a cleaning system of this type is that the residual toner particles remain adhering to the carrier granules.
Thus, these residual toner particles must be removed from the carrier granules in order to successfully perform the cleaning operation over long periods of time. Various types of techniques have been employed to overcome this problem. The following disclosures appear to be relevant:
U. 5. Patent No. 3~580,673 Patentee: Yang Issued: May 25, 1971 U. S. Patent No.3,920,329 Patentee: Dennie et al.
Issued: NovembeE 18, 1975 U. S. Patent No. 4,006,987 Patentee: Tomono et al.
Issued: February 8, 1977 The pertinent portions of the foregoing dis~
closures may be briefly summarized as follows:
Yang discloses an apparatus for cleaning toner particles from a recording surface. The apparatus includes a rotatably mounted non-magnetic cylindrical member housing a permanent bar magnet. The cylindrical member moves magnetic beads into contact with the re-cording surface. An electrical bias opposite in polar-ity to the polarity of the toner particles is applied 3~.
thereto. The electrical bias is sufficient to attract the toner particles to the cleaning beads. A conductive roll is positioned in contact with the magnetic beads.
The roll is electrically biased to the same polarity as the cylindrical member with their magnitude being sufficiently high to attract the toner particles from the cleaning beads thereto.
Dennie describes a background removal appara-tus including a magnetic brush for removing background toner from a pho~oreceptor. The magnetic brush has a rotatably mounted, non-magnetic cylinder with two permanent bar magnets being positioned interiorly thereof As the cylinder rotates, it advances magne-tic carrier beads into contact with the photoreceptor to triboelectrically attrac~ the background toner thereto. The magnetic brush is electrically biased to a positive polarity. A re-claim roller is posi-tioned closely adjacent to the magnetic brush and also biased to a positive polarity of a greater magnitude to attract the particles from the carrier granules thereto. The re-claim roller is made from a non-magnetic material e.g. non-magnetic stainless steel.
Tomono et al. discloses an apparatus for cleaning residual toner from an electrostatic record-ing medium. The cleaning apparatus includes an elec-trically biased, rotatably mounted cylindrical sleeve.
Permanenet magnets are mounted fixedly interiorly of the sleeve. As the sleeve rotates, magnetic particles adhering thereto contact the recording medium and tri-boelectrically attract the residual toner thereto.
A roller contacts the magnetic particles to attract the residual toner therefrom. The roller comprises an electrically grounded conductive metal cylinder having an insulating layer coated thereon.
In accordance with the features of the present invention, there is provided an apparatus for cleaning ?1 particles from a surface. The apparatus includes meansfor transporting a cleaning material into contact with the surface. The transporting means is electrically biased to a polarity and magnitude sufficient to attract the par-ticles from the surface to the cleaning materialO Means,electrically non-conducting, is electrically biased to the same polarity as the transporting means and to a magni- ~
tude greater than the magnitude electrically biasing the transporting means to attract the particles from the clean-ing material thereto.
Another aspect of this invention is as follows:
An electrophotographic printing machine of the type having particles adhering to the surface of the photoconductive member, wherein the improvement includes:
means for transporting a cleaning material into contact with the surfàce of the photoconductive member, said transporting means being electrically biased to a polarity and magnitude sufficient to attract the particles from the surace of the photoconducti~e member to the cleaning material; and non-electrically conductiue means, electrically biased to the same polarity as said transporting means and to a magnitude greater than the magnitude electrical-ly biasing said transporting means~ for attracting the particles from the cleaning material thereto.
Other aspec~s of the present invention will become apparent as the following description proceeds and upon re~erence to the drawings, in which:
Figure 1 is a schematic elevational view depict-ing an electrophotographic printing machine incorporatingthe ~eatures of the present invention therein; and Figure 2 is a schematic elevational view showing the cleaning apparatus used in the Figure 1 printing machine.
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-4a-While the present invention will hereinafter be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the inven~ion to that embodimPnt. On the contrary, it is intended to cover all alternatives, modifications and equivalents as ma~ be included within the spirit and scope of the invention as defined by the appended claimsO
For a general understanding of the features of the present invention, reference is made to the drawings.
In the drawings, like reference numexals have been used throughout to designate identical elements. Figure 1 schematically depicts the various components of an illus~
trative electrophotographic printing machinP incorpo-rating the cleaning system of the present invention therein. It will become evident from the following ,,~
discussion that the cleaning system described herein-after is equally well suited for use in a wide variety of electrostatosraphic printing machines and is not necessarily limited in its application to the particular embodiment shown herein.
Inasmuch as the art of electrophotographic printing is well known, the various processing stations employed in the Figure 1 printing machine will be shown hereinafter schematically and their operation described briefly with reference thereto.
As shown in Figure 1, the electrophotographic printing machine employs a drum, indicated generally by the reference numeral 10. Preferably, drum 10 in-cludes a conductive substrate, such as aluminum, hav-ing a photoconductive material e.g., a selenium alloy,deposited thereon. Drum 10 rotates in the direction of arrow 12 to pass through the various processing stations disposed thereabout.
Initially, drum 10 moves a portion of the photoconductive surface through charging station A.
At charging station A, a corona generating device, indicated generally by the reference numeral 14, charges the photoconductive surface of drum 10 to a relatively high, substantially uniform poten-tial.
Thereafter, the charged portion of the photo-conductive surface of drum 10 is advanced through ex-posure station B. At exposure station B, an original document is placed face-down upon a transparent platen.
The exposure system, indicated generally by the refer-ence numeral 16, includes a lamp which moves across the original document illuminating incremental widths thereof. The light rays reflected from the original document are txansmitted through a moving lens system to form incremental width light images. These light images are focused onto the charged portion of the photoconductive surface~ In this manner, the charged r~3 photoconductive surface of drum 10 is discharged selec-tively by the light images of the original document.
This records an electrostatic latent image on the photo-conductive surface which corresponds to the informational S areas contained within the original document. It has been found that illuminating the charged portion of the photoconductive surface fails to totally discharge the photoconductive surface. Thus, the photoconductive surface re~ains background charge areas which are of some residual voltage level. For example, the back-ground areas may have a nominal potential of about 50 volts while the elec~rostatic latent image or image areas may have a nominal potential of about 350 volts.
Next ! drum lO advances the electrostatic latent image recorded on the photoconductive surface to develop-ment station C. At development station C, a magnetic brush development system, indicated generally by the reference numeral 18, transports the developer material into contact with the photoconductive surface of drum lO. The toner particles are attractd from the carrier granules to the electrostatic latent image forming a toner powder image corresponding to the informational areas of the original document.
Continuing now with the various processing stations disposed in the electrophotographic printing machine, ater depositing the powder image on the photoconductive surface, drum lO advances the powder image to transfer station D. AL transfer station D, a ~heet ~f support material is positioned in contact with the powder image formed on the photoconductive`
surface of drum lO. The sheet of suppor~ material is advanced to transfer station D by a sheet feeding apparatus, indicated generally by the reference numeral 20. Preferably, sheet ~eeding apparatus 20 includes a feed roll 22 contacting the uppermost sheet of the stack 24 of sheets of support material. Feed roll 22 rotates in the direction of arrow 26 so as to advance the uppermost sheet from stack 24. Registration rollers ~8, rotating in the direction of arrow 30, align and forward the advancing sheet of support material into chute 32. Chute 3~ directs the advancing sheet of support material into contact with the photoconductive surface of drum 10 in a timed sequence. This insures that the powder ima~e contacts the advancing sheet of support material at transfer station D.
Transfer station D includes a corona generat-ing device 34, which applies a spray of ions to the backside of the sheet. This attracts the powder image from the photoconductive surface of drum 10 to the sheet. After transfer, the sheet continues to move with drum 10. A detack corona generating device (not shown) neutralizes the charge causing the sheet to adhere to the drum. The sheet is then separated from drum 10. Conveyor 36 advances the sheet in the direc-tion of arrow 38, from transfer station D to fusing station E.
Fusing station E, indicated generally by the reference numeral 40, includes a back~up roller 42 and a heated fuser roller 44. A sheet of support material with the powder image thereon passes between back-up roller 42 and fuser roller 44. The powder image contacts fuser roller 44 and the heat and pressure applied thereto permanently afEixes it to the sheet of support material. After fusing, forwarding rollers ~6 advance the finished copy sheet to catch tray 48. Once a copy sheet is positioned in catch tray 48, it may be readily removed therefrom by the machine operator.
Invariably, after the sheet of support mat-erial is separated from the photoconductive surface of drum 10, some residual toner particles remain adher-ing thereto. These particles are cleaned from thephotoconductive surface of drum 10 at cleaning station F. Preferably, cleaning station F includes a cleaning system 50 which attracts the toner particles from the photoconductive surface of drum 10 thereto. The de-tailed structure of cleaning system 50 will be described hereinafter with reference to Figure 2.
It is believed that the foregoing description is sufficient for purposes of the present invention to illustrate the general operation of an electrophoto graphic printing machine incorporating the cleaning apparatus of the present invention therein.
Referring now to the specific subject matter of the present invention, Figure 2 depicts cleaning apparatus 50 in greater detail. As shown thereat, cleaning apparatus 50 comprises a cylindrical magnet 52 having a plurality of magnetic poles impressed about the circumferential surface thereof. A non-magnetic, conductive, tubular member 54 is interfit over magnet 52. The interior circumferential surface of tube 54 is spaced from the exterior circumferential surface of magnet 52. Tube 54 is mounted rotatably. A con-stant speed motor rotates ~ube 54 at a substantially constant angular velocity. Preferably, magnet 52 is made from b~rium ferrite with tube 54 being made from aluminum. Magnet 52 is mounted fixedly and remains substan-tially stationary as tube 54 rotates in the direction of arrow 56. As tube 54 rotates in the direc-tion of arrow 56, it passes through housing 58. Hous-ing 58 stores a supply of magnetic granules. These magnetic granules are attracted to tube 54. Voltage source 60 is connected to tube 54 and applies a D.C.
electrical field thereto. Preferably, the polarity of this field is opposite to that of the toner parti-cles adhering to the photoconductive surface of drum 10 and of a magnitude sufficient to attract the toner particles from the photoconductive surface to the mag-netic particles adhering to tube 54. The magnetic ~ 3 ~L . 3 ~
g particles are selected so that the toner particles have a triboelectric affinity thereto. Preferably, voltage source 60 electrically biases tubular member 54 to a voltage level ranging from about 300 to about 500 volts.
Roller 62 is positioned closely adjacent to tube 54. As roller 6~ rotates in the direction of arrow 64, it attracts the toner particles from the magnetic particles adhering to tube 54. Voltage source 66 electrically biases roller 62 to the same polarity as voltage source 60 electrically biases tube 54.
However, the magnitude of the electrical bias applied by voltage source 66 to roller 62 is yreater than the electrical bias applied by voltage source 60 to tube 54. For example, the magnitude of the electrical bias applied to roller 62 may range from about 300 to about 500 volts with the specific magnitude selected being greater than the magnitude of the electrical bias applied to tube 54. Preferably, roller 62 is made from aluminum having a coating of aluminum oxide thereon. Preferably, the layer of aluminum oxide ranges from about 20 microns to about 30 microns thick.
A metering blade 68 is located closely adjacent to roller 62 for removing the toner particles there-from. Metering blade 68 deflects or shears the tonerparticles from roller 62 into the chamber of housing 70. Toner particles fall into the chamber of housing 70 under the influence of gravity. These toner parti-cles may be recycled for subsequent re-use in the print-3~ ing machine development system. By way of example,blade 68 may be made from sheet metal e~tending across the width of roller 62.
In recapitulation, it is clear that the im-proved cleaning system of the present invention removes residual toner particles adhering to the photoconductive surface after transfer of the powder image to the sheet of support material. The cleaning apparatus comprises 3~.
a magnetic transport which advances magnetic particles having a triboelectric affinity into contact with the residual toner particles. The magnetic transport is electrically biased to a suitable polarity and magnitude to attract the toner particles from the photoconductive surface to the magnetic particles adhering thereto.
The toner particles, in turn, are removed ~rom the magnetic particles by being attxacted to a roller ~hich is electrically biased to the same polarity as the magnetic transpor~ with the magnitude thereo~ being greater than the magnitude of the electrical bias applied to the magnetic transport. A metering blade removes the residual toner particles from the roller and deflects them into the chamber of a housing for subsequent reuse in the printing machine.
It is, therefore, eveident that there has been provided, in accordance with the present invention, an apparatus for cleaning a photoconductive surface which fully satisfies the aims and advantages herein-before set forth. While this invention has been des-cribed in conjunction with a specific embodiment ~hereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. According, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.
This invention relates generally to an elec-trophotographic printing machine, and more particularly concerns an improved cleaning system for use therein.
In electrophotographic printing, a photocon-ductive member is charged to sensitize the surface thereof. The charged photoconductive member is exposed to a light image of an original document being repro-lQ duced. Exposure of the sensitized photoconductivesurface discharges the charge selectively. This re-cords an electrostatic latent image on the photoconduc-tive surface corresponding to the informational areas contained within the original document being reproduced.
Development of the electrostatic latent image recorded on the photoconductive surface is achieved by bringing a developer material into contact therewith. Typical developer materials comprise a heat settable plastic powder, known in the art as toner particles, which adhere triboelectrically to coarser magnetic carrier granules, such as ferromagnetic granules~ The toner particles are selected to have the appropriate charge relative to the electrostatic latent image recorded on the photoconductive surface. When the developer 2S material is brought into contact with the latent image recorded on the photoconductive surrace, a greater attractive force thereof causes the toner particles to transfer from the carrier granules to the electro-static latent image.
Frequently, residual toner particles remain adhering to the photoconductive surface after the transfer thereof to the sheet of support material.
Hereinbefore, ordinary cleaning devices such as brushes or foam rollers, have not been entirely satisfactory in cleaning residual part~cles from the photoconduc-tive surface. One of the more attractive methods for cleaning particles from the photoconductive surface has been to use a rotating magnet enclosed in a sta-tionary, non-magnetic shell. This system attracts carrier granules which, in turn, attract triboelectri-cally the residual toner particles from the photocon-ductive surface. One of the problems assiciated with a cleaning system of this type is that the residual toner particles remain adhering to the carrier granules.
Thus, these residual toner particles must be removed from the carrier granules in order to successfully perform the cleaning operation over long periods of time. Various types of techniques have been employed to overcome this problem. The following disclosures appear to be relevant:
U. 5. Patent No. 3~580,673 Patentee: Yang Issued: May 25, 1971 U. S. Patent No.3,920,329 Patentee: Dennie et al.
Issued: NovembeE 18, 1975 U. S. Patent No. 4,006,987 Patentee: Tomono et al.
Issued: February 8, 1977 The pertinent portions of the foregoing dis~
closures may be briefly summarized as follows:
Yang discloses an apparatus for cleaning toner particles from a recording surface. The apparatus includes a rotatably mounted non-magnetic cylindrical member housing a permanent bar magnet. The cylindrical member moves magnetic beads into contact with the re-cording surface. An electrical bias opposite in polar-ity to the polarity of the toner particles is applied 3~.
thereto. The electrical bias is sufficient to attract the toner particles to the cleaning beads. A conductive roll is positioned in contact with the magnetic beads.
The roll is electrically biased to the same polarity as the cylindrical member with their magnitude being sufficiently high to attract the toner particles from the cleaning beads thereto.
Dennie describes a background removal appara-tus including a magnetic brush for removing background toner from a pho~oreceptor. The magnetic brush has a rotatably mounted, non-magnetic cylinder with two permanent bar magnets being positioned interiorly thereof As the cylinder rotates, it advances magne-tic carrier beads into contact with the photoreceptor to triboelectrically attrac~ the background toner thereto. The magnetic brush is electrically biased to a positive polarity. A re-claim roller is posi-tioned closely adjacent to the magnetic brush and also biased to a positive polarity of a greater magnitude to attract the particles from the carrier granules thereto. The re-claim roller is made from a non-magnetic material e.g. non-magnetic stainless steel.
Tomono et al. discloses an apparatus for cleaning residual toner from an electrostatic record-ing medium. The cleaning apparatus includes an elec-trically biased, rotatably mounted cylindrical sleeve.
Permanenet magnets are mounted fixedly interiorly of the sleeve. As the sleeve rotates, magnetic particles adhering thereto contact the recording medium and tri-boelectrically attract the residual toner thereto.
A roller contacts the magnetic particles to attract the residual toner therefrom. The roller comprises an electrically grounded conductive metal cylinder having an insulating layer coated thereon.
In accordance with the features of the present invention, there is provided an apparatus for cleaning ?1 particles from a surface. The apparatus includes meansfor transporting a cleaning material into contact with the surface. The transporting means is electrically biased to a polarity and magnitude sufficient to attract the par-ticles from the surface to the cleaning materialO Means,electrically non-conducting, is electrically biased to the same polarity as the transporting means and to a magni- ~
tude greater than the magnitude electrically biasing the transporting means to attract the particles from the clean-ing material thereto.
Another aspect of this invention is as follows:
An electrophotographic printing machine of the type having particles adhering to the surface of the photoconductive member, wherein the improvement includes:
means for transporting a cleaning material into contact with the surfàce of the photoconductive member, said transporting means being electrically biased to a polarity and magnitude sufficient to attract the particles from the surace of the photoconducti~e member to the cleaning material; and non-electrically conductiue means, electrically biased to the same polarity as said transporting means and to a magnitude greater than the magnitude electrical-ly biasing said transporting means~ for attracting the particles from the cleaning material thereto.
Other aspec~s of the present invention will become apparent as the following description proceeds and upon re~erence to the drawings, in which:
Figure 1 is a schematic elevational view depict-ing an electrophotographic printing machine incorporatingthe ~eatures of the present invention therein; and Figure 2 is a schematic elevational view showing the cleaning apparatus used in the Figure 1 printing machine.
~,',:,! ' ' .. . .
q~
-4a-While the present invention will hereinafter be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the inven~ion to that embodimPnt. On the contrary, it is intended to cover all alternatives, modifications and equivalents as ma~ be included within the spirit and scope of the invention as defined by the appended claimsO
For a general understanding of the features of the present invention, reference is made to the drawings.
In the drawings, like reference numexals have been used throughout to designate identical elements. Figure 1 schematically depicts the various components of an illus~
trative electrophotographic printing machinP incorpo-rating the cleaning system of the present invention therein. It will become evident from the following ,,~
discussion that the cleaning system described herein-after is equally well suited for use in a wide variety of electrostatosraphic printing machines and is not necessarily limited in its application to the particular embodiment shown herein.
Inasmuch as the art of electrophotographic printing is well known, the various processing stations employed in the Figure 1 printing machine will be shown hereinafter schematically and their operation described briefly with reference thereto.
As shown in Figure 1, the electrophotographic printing machine employs a drum, indicated generally by the reference numeral 10. Preferably, drum 10 in-cludes a conductive substrate, such as aluminum, hav-ing a photoconductive material e.g., a selenium alloy,deposited thereon. Drum 10 rotates in the direction of arrow 12 to pass through the various processing stations disposed thereabout.
Initially, drum 10 moves a portion of the photoconductive surface through charging station A.
At charging station A, a corona generating device, indicated generally by the reference numeral 14, charges the photoconductive surface of drum 10 to a relatively high, substantially uniform poten-tial.
Thereafter, the charged portion of the photo-conductive surface of drum 10 is advanced through ex-posure station B. At exposure station B, an original document is placed face-down upon a transparent platen.
The exposure system, indicated generally by the refer-ence numeral 16, includes a lamp which moves across the original document illuminating incremental widths thereof. The light rays reflected from the original document are txansmitted through a moving lens system to form incremental width light images. These light images are focused onto the charged portion of the photoconductive surface~ In this manner, the charged r~3 photoconductive surface of drum 10 is discharged selec-tively by the light images of the original document.
This records an electrostatic latent image on the photo-conductive surface which corresponds to the informational S areas contained within the original document. It has been found that illuminating the charged portion of the photoconductive surface fails to totally discharge the photoconductive surface. Thus, the photoconductive surface re~ains background charge areas which are of some residual voltage level. For example, the back-ground areas may have a nominal potential of about 50 volts while the elec~rostatic latent image or image areas may have a nominal potential of about 350 volts.
Next ! drum lO advances the electrostatic latent image recorded on the photoconductive surface to develop-ment station C. At development station C, a magnetic brush development system, indicated generally by the reference numeral 18, transports the developer material into contact with the photoconductive surface of drum lO. The toner particles are attractd from the carrier granules to the electrostatic latent image forming a toner powder image corresponding to the informational areas of the original document.
Continuing now with the various processing stations disposed in the electrophotographic printing machine, ater depositing the powder image on the photoconductive surface, drum lO advances the powder image to transfer station D. AL transfer station D, a ~heet ~f support material is positioned in contact with the powder image formed on the photoconductive`
surface of drum lO. The sheet of suppor~ material is advanced to transfer station D by a sheet feeding apparatus, indicated generally by the reference numeral 20. Preferably, sheet ~eeding apparatus 20 includes a feed roll 22 contacting the uppermost sheet of the stack 24 of sheets of support material. Feed roll 22 rotates in the direction of arrow 26 so as to advance the uppermost sheet from stack 24. Registration rollers ~8, rotating in the direction of arrow 30, align and forward the advancing sheet of support material into chute 32. Chute 3~ directs the advancing sheet of support material into contact with the photoconductive surface of drum 10 in a timed sequence. This insures that the powder ima~e contacts the advancing sheet of support material at transfer station D.
Transfer station D includes a corona generat-ing device 34, which applies a spray of ions to the backside of the sheet. This attracts the powder image from the photoconductive surface of drum 10 to the sheet. After transfer, the sheet continues to move with drum 10. A detack corona generating device (not shown) neutralizes the charge causing the sheet to adhere to the drum. The sheet is then separated from drum 10. Conveyor 36 advances the sheet in the direc-tion of arrow 38, from transfer station D to fusing station E.
Fusing station E, indicated generally by the reference numeral 40, includes a back~up roller 42 and a heated fuser roller 44. A sheet of support material with the powder image thereon passes between back-up roller 42 and fuser roller 44. The powder image contacts fuser roller 44 and the heat and pressure applied thereto permanently afEixes it to the sheet of support material. After fusing, forwarding rollers ~6 advance the finished copy sheet to catch tray 48. Once a copy sheet is positioned in catch tray 48, it may be readily removed therefrom by the machine operator.
Invariably, after the sheet of support mat-erial is separated from the photoconductive surface of drum 10, some residual toner particles remain adher-ing thereto. These particles are cleaned from thephotoconductive surface of drum 10 at cleaning station F. Preferably, cleaning station F includes a cleaning system 50 which attracts the toner particles from the photoconductive surface of drum 10 thereto. The de-tailed structure of cleaning system 50 will be described hereinafter with reference to Figure 2.
It is believed that the foregoing description is sufficient for purposes of the present invention to illustrate the general operation of an electrophoto graphic printing machine incorporating the cleaning apparatus of the present invention therein.
Referring now to the specific subject matter of the present invention, Figure 2 depicts cleaning apparatus 50 in greater detail. As shown thereat, cleaning apparatus 50 comprises a cylindrical magnet 52 having a plurality of magnetic poles impressed about the circumferential surface thereof. A non-magnetic, conductive, tubular member 54 is interfit over magnet 52. The interior circumferential surface of tube 54 is spaced from the exterior circumferential surface of magnet 52. Tube 54 is mounted rotatably. A con-stant speed motor rotates ~ube 54 at a substantially constant angular velocity. Preferably, magnet 52 is made from b~rium ferrite with tube 54 being made from aluminum. Magnet 52 is mounted fixedly and remains substan-tially stationary as tube 54 rotates in the direction of arrow 56. As tube 54 rotates in the direc-tion of arrow 56, it passes through housing 58. Hous-ing 58 stores a supply of magnetic granules. These magnetic granules are attracted to tube 54. Voltage source 60 is connected to tube 54 and applies a D.C.
electrical field thereto. Preferably, the polarity of this field is opposite to that of the toner parti-cles adhering to the photoconductive surface of drum 10 and of a magnitude sufficient to attract the toner particles from the photoconductive surface to the mag-netic particles adhering to tube 54. The magnetic ~ 3 ~L . 3 ~
g particles are selected so that the toner particles have a triboelectric affinity thereto. Preferably, voltage source 60 electrically biases tubular member 54 to a voltage level ranging from about 300 to about 500 volts.
Roller 62 is positioned closely adjacent to tube 54. As roller 6~ rotates in the direction of arrow 64, it attracts the toner particles from the magnetic particles adhering to tube 54. Voltage source 66 electrically biases roller 62 to the same polarity as voltage source 60 electrically biases tube 54.
However, the magnitude of the electrical bias applied by voltage source 66 to roller 62 is yreater than the electrical bias applied by voltage source 60 to tube 54. For example, the magnitude of the electrical bias applied to roller 62 may range from about 300 to about 500 volts with the specific magnitude selected being greater than the magnitude of the electrical bias applied to tube 54. Preferably, roller 62 is made from aluminum having a coating of aluminum oxide thereon. Preferably, the layer of aluminum oxide ranges from about 20 microns to about 30 microns thick.
A metering blade 68 is located closely adjacent to roller 62 for removing the toner particles there-from. Metering blade 68 deflects or shears the tonerparticles from roller 62 into the chamber of housing 70. Toner particles fall into the chamber of housing 70 under the influence of gravity. These toner parti-cles may be recycled for subsequent re-use in the print-3~ ing machine development system. By way of example,blade 68 may be made from sheet metal e~tending across the width of roller 62.
In recapitulation, it is clear that the im-proved cleaning system of the present invention removes residual toner particles adhering to the photoconductive surface after transfer of the powder image to the sheet of support material. The cleaning apparatus comprises 3~.
a magnetic transport which advances magnetic particles having a triboelectric affinity into contact with the residual toner particles. The magnetic transport is electrically biased to a suitable polarity and magnitude to attract the toner particles from the photoconductive surface to the magnetic particles adhering thereto.
The toner particles, in turn, are removed ~rom the magnetic particles by being attxacted to a roller ~hich is electrically biased to the same polarity as the magnetic transpor~ with the magnitude thereo~ being greater than the magnitude of the electrical bias applied to the magnetic transport. A metering blade removes the residual toner particles from the roller and deflects them into the chamber of a housing for subsequent reuse in the printing machine.
It is, therefore, eveident that there has been provided, in accordance with the present invention, an apparatus for cleaning a photoconductive surface which fully satisfies the aims and advantages herein-before set forth. While this invention has been des-cribed in conjunction with a specific embodiment ~hereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. According, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.
Claims (8)
1. An electrophotographic printing machine of the type having particles adhering to the surface of the photoconductive member, wherein the improvement includes:
means for transporting a cleaning material into contact with the surface of the photoconductive member, said transporting means being electrically biased to a polarity and magnitude sufficient to attract the particles from the surface of the photoconductive member to the cleaning material; and non-electrically conductive means, electrically biased to the same polarity as said transporting means and to a magnitude greater than the magnitude electrical-ly biasing said transporting means, for attracting the particles from the cleaning material thereto.
means for transporting a cleaning material into contact with the surface of the photoconductive member, said transporting means being electrically biased to a polarity and magnitude sufficient to attract the particles from the surface of the photoconductive member to the cleaning material; and non-electrically conductive means, electrically biased to the same polarity as said transporting means and to a magnitude greater than the magnitude electrical-ly biasing said transporting means, for attracting the particles from the cleaning material thereto.
2. A printing machine according to claim 1, wherein said attracting means includes a roller positioned close-ly adjacent to said tubular member.
3. A printing machine according to claim 2, further including a roller voltage source coupled to said roller, said roller voltage source electrically biasing said roller to a first polarity and a first magnitude.
4. A printing machine according to claim 3, wherein said roller is preferably made from aluminum having a layer of aluminum oxide coated thereon.
5. A printing machine according to claim 4, wherein said transporting means includes:
a non-magnetic tubular member closely spaced to the surface of the photoconductive member; and a magnetic member disposed interiorly of and being spaced from the interior peripheral surface of said tubular member.
a non-magnetic tubular member closely spaced to the surface of the photoconductive member; and a magnetic member disposed interiorly of and being spaced from the interior peripheral surface of said tubular member.
6. A printing machine according to claim 5, further including a tube voltage source coupled to said tubular member, said tube voltage source electrically biasing said tubular member to a second polarity and second magnitude with the second polarity being the same as the first polarity and the second magnitude being less than the first magnitude.
7. A printing machine according to claim 6, further including:
means for removing the particles from said roller; and means for storing the particles removed from said roller.
means for removing the particles from said roller; and means for storing the particles removed from said roller.
8. A printing machine according to claim 7, wherein the cleaning material includes magnetic granules.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13080580A | 1980-03-17 | 1980-03-17 | |
| US130,805 | 1980-03-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1184591A true CA1184591A (en) | 1985-03-26 |
Family
ID=22446417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000371911A Expired CA1184591A (en) | 1980-03-17 | 1981-02-27 | Magnetic brush cleaning system |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0036290B1 (en) |
| JP (1) | JPS56143477A (en) |
| AU (1) | AU541174B2 (en) |
| BR (1) | BR8101511A (en) |
| CA (1) | CA1184591A (en) |
| DE (1) | DE3167540D1 (en) |
| ES (1) | ES500457A0 (en) |
| MX (1) | MX150481A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0244304Y2 (en) * | 1980-08-30 | 1990-11-26 | ||
| US4547063A (en) * | 1983-07-25 | 1985-10-15 | Xerox Corporation | Moving magnet cleaner |
| US4705387A (en) * | 1983-12-21 | 1987-11-10 | Xerox Corporation | Cleaning apparatus for charge retentive surface |
| JPH0349049Y2 (en) * | 1985-03-13 | 1991-10-21 | ||
| US4819026A (en) * | 1987-12-21 | 1989-04-04 | Xerox Corporation | Cleaning apparatus for a charge retentive surface |
| US4989047A (en) * | 1989-12-11 | 1991-01-29 | Xerox Corporation | Cleaning apparatus for the reduction of agglomeration-caused spotting |
| US5737670A (en) * | 1990-05-12 | 1998-04-07 | Minolta Co., Ltd. | Forming method and apparatus |
| US5124757A (en) * | 1990-06-25 | 1992-06-23 | Minolta Camera Kabushiki Kaisha | Image forming method and apparatus including treatment and collection of residual developer |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4837382B1 (en) * | 1968-08-26 | 1973-11-10 | ||
| JPS51146831A (en) * | 1975-06-11 | 1976-12-16 | Ricoh Co Ltd | Photo-sensible element non-image part cleaning method and its device |
-
1981
- 1981-02-27 CA CA000371911A patent/CA1184591A/en not_active Expired
- 1981-03-06 AU AU68146/81A patent/AU541174B2/en not_active Ceased
- 1981-03-10 JP JP3447581A patent/JPS56143477A/en active Granted
- 1981-03-11 EP EP19810301015 patent/EP0036290B1/en not_active Expired
- 1981-03-11 DE DE8181301015T patent/DE3167540D1/en not_active Expired
- 1981-03-13 BR BR8101511A patent/BR8101511A/en not_active IP Right Cessation
- 1981-03-16 MX MX18638681A patent/MX150481A/en unknown
- 1981-03-17 ES ES500457A patent/ES500457A0/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56143477A (en) | 1981-11-09 |
| BR8101511A (en) | 1981-09-22 |
| AU6814681A (en) | 1981-09-24 |
| EP0036290B1 (en) | 1984-12-05 |
| ES8206869A1 (en) | 1982-08-16 |
| EP0036290A1 (en) | 1981-09-23 |
| DE3167540D1 (en) | 1985-01-17 |
| MX150481A (en) | 1984-05-14 |
| AU541174B2 (en) | 1984-12-20 |
| ES500457A0 (en) | 1982-08-16 |
| JPH0154708B2 (en) | 1989-11-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |