US3784190A - Sheet removing apparatus - Google Patents

Sheet removing apparatus Download PDF

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Publication number
US3784190A
US3784190A US00212359A US3784190DA US3784190A US 3784190 A US3784190 A US 3784190A US 00212359 A US00212359 A US 00212359A US 3784190D A US3784190D A US 3784190DA US 3784190 A US3784190 A US 3784190A
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US
United States
Prior art keywords
sheet
nozzle assembly
transfer sheet
image
transfer
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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
US00212359A
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English (en)
Inventor
R Crawford
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.)
International Business Machines Corp
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International Business Machines Corp
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Publication date
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Publication of US3784190A publication Critical patent/US3784190A/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
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6532—Removing a copy sheet form a xerographic drum, band or plate

Definitions

  • the separating apparatus utilizes a nozzle [51] B65h 5/06 assembly having a plurality of nozzles mounted near [58] Fie'ld DIG 2 the electrophotographic surface.
  • a high velocity flow 271/74 3 2 of pressurized fluid from the nozzles for a predetermined time is sufficient to detact the leading edge of the sheet and a lower velocity flow of pressurized fluid [56]
  • References Cited from the nozzles is sufficient to hold the copy sheet UNITED STATES PATENTS closely adjacent to the nozzle assembly and permit 3,506,259 4/l970 Caldwell 271/80 movement of the copy sheet across the nozzle assemgq t bly to a sheet transport toward a fusing station.
  • One prior art apparatus for transferring a developed image to a copy sheet comprises a system wherein a corona discharge device is utilized to produce a charge on the back of the copy sheet to attract the image toner from the image-forming surface to the sheet. Due to the transfer charge, an electrostatic bond is produced between the image-forming surface and the sheet and this force must be overcome to separate the sheet bearing the toner image from the image-forming surface.
  • apparatus for separating a transfer sheet bearing loosely adhered image forming material from a moving image forming member to which the transfer sheet is electrostatically attracted comprising nozzle means mounted adjacent the image forming member for producing a high velocity flow of pressurized fluid from the nozzle means for a predetermined time for detaching the leading edge of the transfer sheet and for then producing a low velocity flow of pressurized fluid from the nozzle means to move the transfer sheet adjacent to the nozzle means to permit movement of the transfer sheet across the nozzle means to a utilization station.
  • FIG. 1 is a diagrammatic schematic view of electrophotographic imaging apparatus embodying the sheet removing apparatus of the present invention
  • FIG. 2 is a partial side elevation of the sheet removing apparatus shown in FIG. 1;
  • FIG. 3 is a section view along the lines 33 of the nozzle assembly shown in FIG. 6;
  • FIG. 4 is a section view of an alternate embodiment of the nozzle assembly embodying the invention.
  • FIG. 5 is a plot of pressure applied to the nozzle assembly on a time scale
  • FIG. 6 is a schematic diagram of the air control system for the nozzle assembly
  • FIG. 7 is a plot of the control signals on a time basis applied to selectively control the sheet removing apparatus of the invention.
  • FIG. 8 is a section view of a further embodiment of the nozzle assembly according to the invention.
  • FIG. 1 An example of a particular apparatus in which the subject invention is adapted for use is the electrophotographic imaging apparatus shown in FIG. 1.
  • a rotatable drum 10 carries around its periphery an electrophotographic photoconductive member 12 on which is directed an image which is desired to be reproduced on a suitable insulating transfer member such as copy sheet 14.
  • Drum 10 is driven by suitable belts or gears (not shown) from motor 11 and electrical signals to provide the required control and synchronization of the machine components are provided by control means 15 which may be a computer of an associated data processing system if desired.
  • the surface of the photoconductor 12 is uniformly charged to a predetermined polarity by corona discharge device 16.
  • the image to be reproduced is provided in a form so that a suitable exposure means is operable to direct the image to exposure station 18 onto the surface of the photoconductor 12. Relative motion may be provided during exposure of the image at a speed synchronized with the surface speed of drum 10 in a manner known in the art.
  • the photoconductive surface is illuminated by the image, the surface is discharged leaving a charge pattern in the form of the image to be copied. Either the desired image or the background area may be discharged to produce the desired charge pattern, depending upon whether direct or reversal development is to be used.
  • the drum passes a development station 20 at which a toner carrier mixture 22 is cascaded across i or otherwise brought in contact with the electrostatic image on the surface of the photoconductor 12 as is known in the art.
  • the toner having a charge opposite from the polarity of the electrostatic image charge is attracted to the drum surface to render the image visible.
  • a copy sheet 14 is fed into contact with the developed eleectrostatic image by the transport means 24.
  • a corona discharge device 26 is disposed above the copy sheet at the area of contact with the drum. Corona discharge device 26 produces ionization of a polarity opposite that of the toner sufficient to attract the toner forming the image to the copy sheet.
  • the copy sheet 14 is separated from the drum by separator means 30 and fed by transport means 38 past a fusing station 40 which serves to fuse and permanently fix the image-forming toner to the copy sheet.
  • the nature of the separating means 30 will be described in more detail later. Since transfer of all the image toner 27 is not usually accomplished, residual toner 28 remains on the drum surface after a transfer operation.
  • the drum continues to rotate past a cleaning apparatus 32 which cleans the surface of the photoconductor and removes any excess toner.
  • a pre-clean-corona 29 and an erase lamp 3] may bev placed before cleaning station 32' to aid in cleaning I the photoconductor. This'op'eration completes the cycling of the drum for reproducing the desired image.
  • a sheet separating operation is initiated by a signal FEED SHEET which is generated by control means 15.
  • the signal is generated in synchronism with the position of the image on drum so that a sheet 14 is fed to merge with the toned image on drum 10.
  • the FEED SHEET signal is coupled to actuate single revolution clutch 76 for one cycle of operation of the feed components connected by dashed lines.
  • a cycle of operation results in a sheet being fed from the position shown in FIG. 2 to the drum to receive the toned image from drum 10 while a second sheet is being fed from hopper 78 to be registered at stop 80.
  • the motion of pressure roll 82 to an operative position is coordinated with the position of stop 80 so that stop 80 is moved out of the path of the sheet before the pressure roll 82 is lowered to drive sheet 14. Stop 80 is then moved to the operative position prior to the arrival of the second sheet so that the second sheet is properly registered at stop 80.
  • Sheet 14 is fed to coincide with the toned image on the drum.
  • the transfer corona is energized to produce ions of the proper polarity which are sprayed on the back of sheet 14 to electrostatically attract the image toner to sheet 14.
  • Sheet 14 with the toned image loosely adhering to the surface is then separated from drum 10 by separator means 30.
  • Separator means 30 comprises a nozzle assembly 34 which is mounted in a fixed position near the surface of drum 10.
  • Nozzle assembly 34 comprises a plurality of individual nozzles 36 through each of which a relatively high velocity stream of pressurized fluid is 7 the invention is operable to remove thecopy sheet ejected as the leading edge of copy sheet 14 approaches the nozzle assembly.
  • the individual nozzles are designed to produce a blast of fluid directed substantially tangentially to the surface of the drum. Due to copy sheet 14 being wrapped around curved drum 10, a small portion of the leading edge of the paper may not follow the contour of the drum, thereby making easier the sheet separation operation.
  • my invention reliably separates the sheet from the drum without damage to the toner image.
  • the blast of fluid raises the leading edge of the sheet as the leading edge approaches the nozzle 7 exit point.
  • a relatively lower volume of fluid is introduced through the individual nozzles so that the movement of the fluid between the individual nozzles 36 and copy sheet '14 creates a partial vacuum, thereby pulling (by Bernoullis principle) the copy sheet leading edge to a position closely approaching, but not touching the nozzle assembly.
  • Sheet transport means 38 comprises a suitable transport such as a vacuum belt transport or electrostatic belt transport, which is effective to convey copy sheet 14 by contacting only the non-image side of sheet 14 through a suitable fusing station 40 in an output means such as stacker 42.
  • separator means is in position to blowfluid on the image side of the sheetonly during the passage of the first fraction of an inch of the leading edge of the sheet. Once this fraction of an inch of the leading edge passes the nozzle 36, the sheet itself is effective to prevent the flow of fluid from reaching the image side of the sheet and all further processing of the sheet prior to the fusing of the image is accomplished entirely by contacting the non-image side of copy sheet 14.
  • nozzle assembly 34 is shown in greater detail in FIGS. 2 and 3.
  • the nozzle assembly extends across the surface of drum l0 and is mounted by suitable support means 46 in a fixed position with surface 35 spaced a relatively small distance from the drum surface.
  • An enclosure which extends across assembly 34 is provided to form a manifold 43 in the nozzle assembly for introducing pressurized fluid such as compressed air into each of the nozzles 36.
  • a plurality of individual nozzles 36 are formed by a contoured opening 45 in the manifold and a shaped diffuser member 44.
  • the nozzle opening 47 formed by fixedly mounting a diffuser member 44 in each contoured opening 45 is preferably designed to form an annular converging nozzle since this design produces greater efficiencyfor reliably removing a sheet bearing an unfused toner image from drum 10.
  • the number of individual nozzles used to cover the drum width is a matter of design choice which depends on the air pressure utilized, the rotational speed of the drum, the weight of the paper and the design characteristics of the nozzles.
  • the pressurized air or other suitable fluid may be provided from any suitable source which produces a sufficient quantity and pressure of air to overcome the force produced by the electrostatic bond between the image forming surface and the copy sheet.
  • a suitable pump 48 is provided to compress the air for storage in storage tank 50 to which a suitable relief valve 52 is attached to provide a predetermined maximum pressure.
  • a first solenoid valve 54 is placed in an output line from tank 50 to provide the pressure to input line 56 for separating the leading edge of copy sheet 14 from the image-forming surface when valve 54 is energized with a suitable electrical signal generated by control means 15 such as the PRIMARY NOZZLES signal shown in FIG. 7.
  • a second air path from tank 50 is provided with a pressure regulator 58 and a second solenoid valve 60 to produce the lower level of pressure suitable for holding the copy sheet to the nozzle assembly.
  • Pressure regulator 58 is set so that the required pressure is provided to input line 62 of nozzle assembly 34 when valve 60 is selectively actuated by a suitable electrical signal generated by control means 15 such as the signal SECONDARY NOZZLES shown in FIG. 7.
  • Each of the solenoid valves 54, 60 may be selectively actuated to provide the pressure to the manifold of nozzle assembly 34.
  • the valves may be actuated at times shown in FIG. 7 to produce the gas pressure as shown in FIG. 5.
  • the sheet is in the approximate position shown in FIG. 1 approaching the nozzle assembly and valve 54 is energized to direct the high pressure gas to the nozzle assembly.
  • the sheet is located at the approximate position shown in FIG. 4 and the lower pressure air is directed to the nozzle assembly by turning off valve 54 and turning on valve 60. This level of pressure is maintained until time T when the sheet is at the approximate position shown in FIG. 3.
  • the lower pressure gas may be left on at all times and obtain reliable operation in which case valve 60 would not be necessary.
  • valves 54, 60 may be actuated mechanically by means of suitable cams which are timed to coincide with the position of the leading edge of the sheet 14 on drum member 10.
  • the position of the sheet on the drum may not be located accurately enough for reliable operation of the separating apparatus, particularly in machines which operate at high process speeds. In other machines the sheet is accurately located on the drum but at a random position on the drum. It is, therefore, preferable to have valves that are selectively operable according to an electric signal which is generated in synchronism with the position of the sheet on the drum.
  • a suitable sensing apparatus such as a photocell is positioned near the surface of the drum at the point of impingement of the light beam on the surface of the drum.
  • the surface of drum l0 reflects the light so that substantially no light reaches the photocell; however, when a sheet is present the light is diffused so that sufficient light reaches the photocell to produce a detectable signal from the photocell output.
  • This signal indicates that the leading edge of a sheet is present and the signal is sent to control means 15 and utilized to generate the signal PRIMARY NOZ- ZLES to actuate the solenoid valve 54 for a sufficient time to separate the leading edge of the sheet.
  • a second signal SECONDARY NOZZLES is generated which actuates solenoid valve 60 to produce the holding level of air for a time sufficient for the leading edge of sheet 14 to reach sheet transport 38.
  • nozzle assembly 34 shown in FIG. 4 may produce more reliable operation.
  • This nozzle assembly utilizes the same primary nozzle assembly that has been previously described; however, an auxiliary nozzle 64 is provided to, ensure even more positive control over the leading edge of the sheet as the leading edge is guided from the drum to the sheet transport 38 to eliminate any possibility that the sheet may be reattached to the surface of drum 10.
  • the auxiliary nozzle comprises a manifold enclosure to which pressurized gas is introduced through line 62'.
  • a contoured portion 68 of the valve assembly in conjunction with shaped deflector member 66 forms the auxiliary nozzle 64 which may extend the width of sheet 14.
  • Auxiliary nozzle 64 produces a flow of air parallel to the sheet path at the same pressure level as the conveying pressure (such as 2 to 4 PSI, for example) in the main nozzle of the embodiment shown in FIG. 3 so that the flow is operable to hold the sheet closely adjacent to the surface but not touching the deflector member 66 of secondary nozzle 64. Since this flow produces no vertical component of force, there is no tendency to force the leading edge of the sheet to reattach itself to the surface of drum 10.
  • This construction has the added advantage that the surface of the main nozzle and the surface of the auxiliary nozzle need not be in the same plane, so the auxiliary nozzle may be utilized to change the angle of the paper path to an extent as well as providing an added safety factor insofar as prevention of reattachment of the copy sheet to the surface of the drum 10.
  • FIG. 8 A further embodiment of a nozzle assembly is shown in FIG. 8.
  • the nozzle assembly comprises a first nozzle 72 to which the stripping pressure (such as 6 to 10 PSI, for example) of pressurized gas is applied through input 56".
  • Nozzle 72 is followed along the direction of paper travel by a plurality of secondary nozzles 74 to which is applied the conveying level of pressurized gas through input 62".
  • a row of nozzles 72, 74 are provided across the width of sheet 14 and the position of nozzles may be staggered if desired.
  • Apparatus for'separating a transfer sheet having image forming toner particles loosely adhered to one surface thereof from a moving image forming member to which the transfer sheet is electrostatically attracted comprising:
  • a first transport means to convey the transfer sheet to a transfer area
  • nozzle assembly means mounted adjacent the path of travel of the non-image surface of the transfer sheet, said nozzle assembly means producing a first direction of flow of pressurized fluid against the direction of movement of the transfer sheet and a second direction of flow of pressurized fluid in the direction of movement of the transfer sheet;
  • second transport means operative on the non-image surface of the transfer sheet to convey the transfer sheet away from the transfer area

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Separation, Sorting, Adjustment, Or Bending Of Sheets To Be Conveyed (AREA)
US00212359A 1971-12-27 1971-12-27 Sheet removing apparatus Expired - Lifetime US3784190A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US21235971A 1971-12-27 1971-12-27

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US3784190A true US3784190A (en) 1974-01-08

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US00212359A Expired - Lifetime US3784190A (en) 1971-12-27 1971-12-27 Sheet removing apparatus

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US (1) US3784190A (enrdf_load_stackoverflow)
JP (1) JPS5220141B2 (enrdf_load_stackoverflow)
FR (1) FR2167188A5 (enrdf_load_stackoverflow)
GB (1) GB1402157A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3885785A (en) * 1973-12-20 1975-05-27 Xerox Corp Vacuum transport
US4034977A (en) * 1975-01-16 1977-07-12 Hoechst Aktiengesellschaft Detaching device for a sheet-shaped copy support
EP0014752A1 (en) * 1978-12-29 1980-09-03 International Business Machines Corporation Printer with and method for duplex printed sheet output
US4252307A (en) * 1978-06-28 1981-02-24 International Business Machines Corporation Sheet feed and transport
US4275968A (en) * 1979-04-30 1981-06-30 Ibm Corporation System for controlling and sequencing a printer
US5337456A (en) * 1990-10-22 1994-08-16 Rieter Machine Works, Ltd. Method and apparatus for opening a wadding lap
US6243556B1 (en) * 1999-03-15 2001-06-05 Samsung Electronics Co., Ltd. Claw apparatus for liquid electrophotographic printer
US20040212146A1 (en) * 2000-07-12 2004-10-28 Peter Wulf Device for guiding sheets

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2614771A1 (de) * 1975-04-07 1976-10-21 Savin Business Machines Corp Abnahmevorrichtung fuer blattfoermiges kopiermaterial in elektrostatischen kopiergeraeten
GB1564859A (en) * 1976-11-18 1980-04-16 Ibm Document copying apparatus
JPS5388734A (en) * 1977-01-14 1978-08-04 Canon Inc Transfer device
US6210515B1 (en) * 1995-02-27 2001-04-03 Moore Business Forms, Inc. Linerless label printer control

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054613A (en) * 1960-12-28 1962-09-18 Warren S D Co Sheet delivery system
US3506259A (en) * 1967-10-12 1970-04-14 Xerox Corp Electrostatic sheet detacking apparatus
US3578859A (en) * 1969-07-03 1971-05-18 Xerox Corp Mechanical stripping apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054613A (en) * 1960-12-28 1962-09-18 Warren S D Co Sheet delivery system
US3506259A (en) * 1967-10-12 1970-04-14 Xerox Corp Electrostatic sheet detacking apparatus
US3578859A (en) * 1969-07-03 1971-05-18 Xerox Corp Mechanical stripping apparatus

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3885785A (en) * 1973-12-20 1975-05-27 Xerox Corp Vacuum transport
US4034977A (en) * 1975-01-16 1977-07-12 Hoechst Aktiengesellschaft Detaching device for a sheet-shaped copy support
US4252307A (en) * 1978-06-28 1981-02-24 International Business Machines Corporation Sheet feed and transport
EP0014752A1 (en) * 1978-12-29 1980-09-03 International Business Machines Corporation Printer with and method for duplex printed sheet output
US4275968A (en) * 1979-04-30 1981-06-30 Ibm Corporation System for controlling and sequencing a printer
US5337456A (en) * 1990-10-22 1994-08-16 Rieter Machine Works, Ltd. Method and apparatus for opening a wadding lap
US6243556B1 (en) * 1999-03-15 2001-06-05 Samsung Electronics Co., Ltd. Claw apparatus for liquid electrophotographic printer
US20040212146A1 (en) * 2000-07-12 2004-10-28 Peter Wulf Device for guiding sheets
US7328899B2 (en) * 2000-07-12 2008-02-12 Man Roland Druckmaschinen Ag Device for guiding sheets

Also Published As

Publication number Publication date
GB1402157A (en) 1975-08-06
JPS4877842A (enrdf_load_stackoverflow) 1973-10-19
DE2262693B2 (de) 1977-05-26
JPS5220141B2 (enrdf_load_stackoverflow) 1977-06-01
FR2167188A5 (enrdf_load_stackoverflow) 1973-08-17
DE2262693A1 (de) 1973-07-12

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