US3650616A - Mispuff detector - Google Patents

Mispuff detector Download PDF

Info

Publication number
US3650616A
US3650616A US111404A US3650616DA US3650616A US 3650616 A US3650616 A US 3650616A US 111404 A US111404 A US 111404A US 3650616D A US3650616D A US 3650616DA US 3650616 A US3650616 A US 3650616A
Authority
US
United States
Prior art keywords
image
transfer
transfer material
electrode
reproducing
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
Application number
US111404A
Other languages
English (en)
Inventor
Fredrick W Hudson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xerox Corp
Original Assignee
Xerox Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Application granted granted Critical
Publication of US3650616A publication Critical patent/US3650616A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • G03G15/70—Detecting malfunctions relating to paper handling, e.g. jams
    • G03G15/706—Detecting missed stripping form xerographic drum, band or plate

Definitions

  • a device for detecting the undesired continued presence of the transfer sheet on the reproducing surface after the image has been transferred, said device including a power source for providing a current flow between an electrode and the reproducing surface at a point beyond the image transfer area and a detecting circuit coupled to the electrode and power source for indicating a change in the current flow caused by the presence of the transfer sheet between the electrode and the surface, thereby indicating continued contact of the transfer sheet with the reproducing surface.
  • the detecting circuit can be used to discontinue the operation of the machine.
  • the formation and development of the images employing photoconductive materials by electrostatic means is well known.
  • the basic electrostatographic process as taught by C. F. Carlson in U.S. Pat. No. 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light-and-shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting electrostatic latent image by depositing on the image a finely divided electroscopic material referred to in the art as toner.
  • the toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image.
  • This powder image may then be transferred to a receiving surface such as paper.
  • the transferred image may be subsequently permanently affixed to a support surface by heat.
  • latent image formulation by uniformly charging the photoconductive layer and then exposing the layer to a light-and-shadow image
  • one may form the latent image by other means such as directly charging the layer in image configuration.
  • Any other suitable fixing means such as solvent or overcoating treatment may be substituted for the foregoing heat fixing step.
  • a difficulty often encountered in apparatus embodying such electrostatographic processes is that jamming can be caused by failure of the transfer material to be timely removed from the photoconductive surface, after transfer of the image.
  • One solution has been to employ photodetection devices positioned at a point on the reproducing surface immediately past the position at which the transfer material is removed. Failure of the transfer material to be timely removed is thus optically detected and an appropriate signal generated for disconnecting the mechanism from the power source to prevent jamming.
  • a disadvantage of photooptical devices lies in their inherent unreliability in field use, their susceptibility to erroneous indications due to ambient light levels and build up of foreign matter interfering with the optical path, their expense, and the inconvenience of adding additional components to the mechanism.
  • Another solution utilizes mechanical fingers which contact the drum and position sense the presence or absence of improperly positioned transfer material. However, this method can result in fatigue and physical damage of the reproducing member due to finger contact.
  • the foregoing objects are accomplished by providing a current flow between an electrode and the photoconductive surface at a position immediately past the point at which the level and thereby indicate the presence of transfer materialpast its point of proper removal. Such indication can be employed to disconnect the mechanism from its power source, and thus prevent jamming.
  • the corona preclean unit may be employed as the current electrode.
  • FIG. 1 is a schematic view of an electrostatographic reproducing apparatus in elevation
  • FIG. 2 is a partial isometric view of the transfer station and photoconductive surface showing the use of the present invention
  • FIG. 3 is a schematic representation of an arrangement for providing an indication of a change in current flow, caused by failure of removal of transfer material, in accordance with the invention.
  • FIGS 4A and 4B are wave form diagrams illustrating the operation of the invention with respect to time.
  • FIG. 1 a typical electrostatographic reproducing apparatus is shown.
  • FIGS. 1 and 2 For a general understanding of the processing system in which the present invention is incorporated, reference is had to FIGS. 1 and 2 wherein like numerals refer to like components in which the various system components are schematically illustrated.
  • a light image of copy to be reproduced is projected onto the charged surface of an electrostatographic plate to form an electrostatic latent image thereon.
  • the latent image is developed with an oppositely charged electroscopic developing material to form a power image, corresponding to the latent image, on the plate surface.
  • the powder image can then be electrostatically transferred to a web of suitable transfer material in sheet form to which it may be fused by a fusing device, whereby the powder image is caused permanently to adhere to said transfer sheet material.
  • documents to be reproduced are placed at the imaging station, generally designated by reference character 11, which includes a light projecting system, for the purpose of scanning.
  • the illuminated data is projected downwardly by means of a mirror-lens imaging assembly 12 and through a slit aperture assembly 13 and onto the reproducing surface of an electrostatographic plate in the form ofa drum 14.
  • the electrostatographic drum 14 includes a cylindrical member mounted in suitable bearings in the frame of the machine and is driven in a clockwise direction as viewed in FIG. 1 by a motor at a constant rate that is proportional to the scan rate whereby the peripheral rate of the drum surface is substantially identical to the rate of movement of the reflected light image.
  • the drum surface comprises a layer of photoconductive material on a grounded conductive backing that is sensitized prior to exposure by means of a corona generating device 15.
  • the exposure of the drum surface of the light image discharges the photoconductive layer in the areas struck by light, whereby there remains on the drum a latent electrostatic image in image configuration corresponding to the light image projected.
  • the electrostatic latent image passes through a developing station in which there is positioned a developer apparatus including a housing 16 for developing material.
  • a suitable driving means is used to carry the developing material to the upper part of the developer housing where it is cascaded down over a hopper chute onto the electrostatographic image on the drum.
  • toner particles are pulled away from the carrier component of the developing material and deposited on the drum to form powder images, while the partially denuded carrier particles pass off the drum into the developer housing sump.
  • an image transfer station Positioned next and adjacent to the developing station in a clockwise direction is an image transfer station which includes a sheet feeding mechanism adapted to feed sheets successively to the developed image on the drum at the transfer station.
  • This sheet feeding mechanism generally designated 18, includes a sheet source for a plurality of sheets of a suitable transfer material that is typically sheets of paper or the like, a separating roller adapted to feed the top sheet of the stack to feed belt and rollers 20 which direct the sheet material into contact with the rotating drum at a speed preferably slightly in excess of the rate of travel of the surface of the drum in coordination with the appearance of the developed image at the transfer station.
  • the sheet material is introduced between the feed rollers and is thereby brought into contact with the rotating drum at the correct time and position to register with the developed image.
  • guides are positioned on opposite sides of the feed rollers.
  • the transfer of the powder image from the drum surface to the transfer material is effected by means of a corona transfer I device 21 that is located at or immediately after the point of contact between the transfer-material and the rotating drum.
  • the corona transfer device 21 is substantially similar to the corona discharge device in that it includes an array of one or more corona discharge electrodes that are energized from a suitable high potential source and extend transversely across the drum surface and are substantially enclosed within a shielding member.
  • the electrostatic field created by the corona transfer device is effective to tack the transfer material electrostatically to the drum surface, thus causing the transfer material to move synchronously with the drum while in contact therewith. Simultaneously with the tacking action, the electrostatic field is effective to attract a significant portion of the toner particles, forming the powder image, from the drum surface and cause them to adhere electrostatically to the surface of the transfer material.
  • a transfer material stripping apparatus or paper pickoff mechanism for removing the transfer material from the drum surface.
  • This device includes a plurality of small diameter, multiple outlet conduits 24 of a manifold that is supplied with pressurized aeriform fluid through the outlet conduits into contact with the surface of the drum slightly in advance of the sheet material to strip the leading edge of the sheet material from the drum surface and to direct it onto a horizontal conveyor 23.
  • the sheet material is then carried to a fixing device in the form of a fuser assembly 25, whereby the developed and transferred powder image on the sheet material is permanently fixed thereto.
  • the finished copy is preferably discharged from the apparatus at a suitable point 26 for external collection, in a copy collector positioned at a convenient place for copy removal by the machine operator.
  • the next and final station in the device is a drum cleaning station having positioned therein a corona precleaning device 27 similar to the corona charging device 15, to impose an electrostatic charge on the drum and residual powder adherent thereto to more readily permit removal of residual or untransferred toner.
  • a drum cleaning device 28 adapted to remove any powder remaining on the drum surface after transfer, is also provided as is a source of light 29 whereby the photoconductive drum is flooded with light to cause dissipation of any residual electrical charge remaining thereon.
  • the electrostatic charging of the electrostatographic drum in preparation for the exposure step and the electrostatic charging of the support surface to effect transfer are accomplished by means of corona generating devices whereby electrostatic charge is applied to the respective surfaces in each instance.
  • corona generating devices any one of a number of types may be used, a corona charging device of the type disclosed in Vyverberg U.S. Pat. No. 2,836,725 is used for both the corona charging device 15,-the corona transfer device 21, and the corona precleaning device 27, each of which is secured to suitable frame elements of the apparatus and connected to suitable power sources.
  • the paper pickoff mechanism 22 is positioned just past the image transfer station. Failure of the burst or puff of aeriform fluid to dislodge the transfer material from the drum 14 at that point will result in jamming of the reproducing apparatus by the sheet material. Such failure is commonly referred to as a miss-puff.”
  • Detection of the miss-puff or failure to remove transfer material is accomplished in accordance with the present invention through use of the corona precleaning device 27, in conjunction with the arrangement as shown in FIG. 3.
  • the principle of operation involves a discontinuity in the level of flow of current from the corona precleaning device 27 caused by alteration of the flow of current between the corona device and the reproducing surface of the drum 14.
  • the al teration of current flow is that created by the miss-puff, i.e., the continued presence of the transfer material in contact with the drum surface.
  • a power supply PS 33 provides energizing potential to the electrode 30 of the preclean device 27.
  • a detector unit DET 35 is coupled to the power supply and electrode to detect the current differential and provide an indication of the current differential resulting from failure of removal of transfer material.
  • FIG. 3 shows a corona precleanin g device 27 having at least one electrode 30.
  • the drum 14 is connected to an electrical reference point 31 illustrated as ground, and includes a suitable photoconductive surface layer 32..
  • the corona precleaning device can be either positive, negative, (AC or in combinations), and as shown is AC biased with a negative potential by means of a power supply 33, which includes a DC voltage source 33B coupled through an AC voltage source 33A to the corona electrode 30.
  • the detector unit 35 is connected between the DC source 33B and the electrical reference point, and can take the form of a half-wave diode rectifier including sensing resistor 36, smoothing capacitors 37 and 38, diode 39, current limiting resistance 40, and loading resistance 41.
  • the potential of source 33 is designed such that under normal conditions, the potential E, at point A varies about a level which prevents any negative excursions.
  • This condition is illustrated in FIG. 4A in time zone t -t
  • no output voltage E is present at point B under these conditions.
  • the resulting unbalance results in a shift in operating voltage levels such that a portion of the potential at point A goes negative, thereby permitting a rectified output voltage E to appear at point B as shown in FIG. 4B in the time zone t -t End of the condition at time results in resumption of the original state.
  • the voltage pulse at point B can be employed to energize a suitable relay unit 42 for shutting off the machine.
  • An example of relay energizable machine stop sequences is shown by Osborne et al. in U.S. Pat. No. 3,301,126.
  • a device for detecting the continued presence of the transfer material on said reproducing surface after said image has been transferred comprising a power source for providing a current flow between an electrode and said reproducing surface at a point beyond said image transfer area, a detecting unit coupled to said power source for detecting a change in said current flow caused by presence of said transfer material between said electrode and said surface, thereby indicating continued contact of said transfer material and said reproducing surface, and means coupled to said detecting unit for providing an indication of said change in current flow.
  • said power source includes a DC source series coupled through an AC source to said electrode, said detecting unit coupled between said DC source and a reference point.
  • a device for detecting failure of removal of said transfer material from said surface after transfer of said image to said material comprising: energizing means for establishing a first current flow between an electrode and said surface at a position on said surface beyond said pick-off means in the absence of transfer material at said position, and a second current flow in the presence of transfer material at said position; and
  • detection means coupled to said energizing means and responsive to the change between said first and second current flows for providing an indication of said failure of said transfer material to be removed from said surface.
  • said power source includes a DC source series coupled through an AC source to said electrode, said detecting unit coupled between said DC source and a reference point.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Cleaning In Electrography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Printing Methods (AREA)
US111404A 1971-02-01 1971-02-01 Mispuff detector Expired - Lifetime US3650616A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11140471A 1971-02-01 1971-02-01

Publications (1)

Publication Number Publication Date
US3650616A true US3650616A (en) 1972-03-21

Family

ID=22338347

Family Applications (1)

Application Number Title Priority Date Filing Date
US111404A Expired - Lifetime US3650616A (en) 1971-02-01 1971-02-01 Mispuff detector

Country Status (8)

Country Link
US (1) US3650616A (https=)
BE (1) BE778739A (https=)
CA (1) CA954181A (https=)
DE (1) DE2204445A1 (https=)
FR (1) FR2125044A5 (https=)
GB (1) GB1374923A (https=)
IT (1) IT947120B (https=)
NL (1) NL7201261A (https=)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3734604A (en) * 1970-09-22 1973-05-22 Agfa Gevaert Ag Failsafe system for electrostatic copying apparatus
US3778222A (en) * 1972-09-18 1973-12-11 Xerox Corp Fire prevention apparatus
US5241276A (en) * 1989-04-28 1993-08-31 Kabushiki Kaisha Toshiba Surface potential measuring system
US6496661B2 (en) * 2000-02-03 2002-12-17 Canon Kabushiki Kaisha Sheet attachment detecting apparatus, fixing apparatus and image forming apparatus
US6718146B2 (en) * 2001-04-24 2004-04-06 Canon Kabushiki Kaisha Image forming apparatus and image forming method
US6744993B2 (en) * 2001-04-24 2004-06-01 Canon Kabushiki Kaisha Sheet winding detecting device and image forming apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2849222A1 (de) 1978-11-13 1980-05-22 Hoechst Ag Verfahren zum elektrostatischen aufladen einer dielektrischen schicht sowie vorrichtung zur durchfuehrung des verfahrens

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1238492B (de) * 1966-02-14 1967-04-13 R & M Leuze Vorrichtung zum Abstellen einer bogenverarbeitenden Maschine beim Auftreten von Doppelbogen oder Fehlstellen
US3360652A (en) * 1964-10-14 1967-12-26 Xerox Corp Fail safe photoelectric sheet sensing machine control circuit
US3506259A (en) * 1967-10-12 1970-04-14 Xerox Corp Electrostatic sheet detacking apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3360652A (en) * 1964-10-14 1967-12-26 Xerox Corp Fail safe photoelectric sheet sensing machine control circuit
DE1238492B (de) * 1966-02-14 1967-04-13 R & M Leuze Vorrichtung zum Abstellen einer bogenverarbeitenden Maschine beim Auftreten von Doppelbogen oder Fehlstellen
US3506259A (en) * 1967-10-12 1970-04-14 Xerox Corp Electrostatic sheet detacking apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3734604A (en) * 1970-09-22 1973-05-22 Agfa Gevaert Ag Failsafe system for electrostatic copying apparatus
US3778222A (en) * 1972-09-18 1973-12-11 Xerox Corp Fire prevention apparatus
US5241276A (en) * 1989-04-28 1993-08-31 Kabushiki Kaisha Toshiba Surface potential measuring system
US6496661B2 (en) * 2000-02-03 2002-12-17 Canon Kabushiki Kaisha Sheet attachment detecting apparatus, fixing apparatus and image forming apparatus
US6718146B2 (en) * 2001-04-24 2004-04-06 Canon Kabushiki Kaisha Image forming apparatus and image forming method
US6744993B2 (en) * 2001-04-24 2004-06-01 Canon Kabushiki Kaisha Sheet winding detecting device and image forming apparatus

Also Published As

Publication number Publication date
GB1374923A (en) 1974-11-20
DE2204445A1 (de) 1972-08-10
NL7201261A (https=) 1972-08-03
IT947120B (it) 1973-05-21
BE778739A (fr) 1972-07-31
FR2125044A5 (https=) 1972-09-22
CA954181A (en) 1974-09-03

Similar Documents

Publication Publication Date Title
US3781107A (en) Cleaning apparatus
US3572923A (en) Cleaning method and apparatus for electrostatic copying machines
US3620615A (en) Sheet stripping apparatus
US3590412A (en) Brush cleaning device for electrostatic machines
JPS6212510B2 (https=)
US3805069A (en) Regulated corona generator
US4533236A (en) Charge particle removal device
US5140375A (en) Image forming apparatus
US5282006A (en) Transfer system including pre-transfer pressure treatment apparatus
US4632537A (en) Electrophotographic apparatus
US3650616A (en) Mispuff detector
US5134442A (en) Electrode wire contamination prevention and detection
US3650619A (en) Switching detector
JPS6325355B2 (https=)
US3650617A (en) Switching detector
US3650618A (en) Switching detector
US5361125A (en) Intermediate transfer member
EP0002914B1 (en) Method of operating a xerographic copier of the transfer type
US3866564A (en) Magnetic brush developing apparatus for copiers
US3887845A (en) Copier photoreceptor charge control
US6006048A (en) Wrong-sign toner detection system
US3819175A (en) Vacuum stripping roll with stationary pickup slots
EP0620508A1 (en) Augmented electrostatic brush
US3921042A (en) Electrostatic reproduction machine with improved corona generating device
US4078520A (en) Vibrating screen filter for toner density measuring apparatus