US3882308A - Detection system for superposed sheets - Google Patents

Detection system for superposed sheets Download PDF

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Publication number
US3882308A
US3882308A US025804A US2580470A US3882308A US 3882308 A US3882308 A US 3882308A US 025804 A US025804 A US 025804A US 2580470 A US2580470 A US 2580470A US 3882308 A US3882308 A US 3882308A
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US
United States
Prior art keywords
sheet
illumination
sheets
path
sheet material
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
US025804A
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English (en)
Inventor
John W Daughton
Gary L Schluntz
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Xerox Corp
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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
Priority to US025804A priority Critical patent/US3882308A/en
Priority to CA096298A priority patent/CA929632A/en
Priority to DE19712116802 priority patent/DE2116802A1/de
Priority to GB2601071*A priority patent/GB1342838A/en
Application granted granted Critical
Publication of US3882308A publication Critical patent/US3882308A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • G03G15/70—Detecting malfunctions relating to paper handling, e.g. jams
    • G03G15/703—Detecting multiple sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/14—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors by photoelectric feelers or detectors

Definitions

  • ABSTRACT A multiple sheet detecting system for use in a sheet feed path to provide a signal to a machine control when superposed sheets are fed past a detection station.
  • the detection system has a source of illumination and photosensitive elements at the detection station.
  • Illumination is interrupted by the presence of a sheet or sheets in the sheet path and also by a sample sheet such that a comparison is made between the sample and fed sheets.
  • An electronic circuit coupled to the photosensitive elements which experience a change in resistance depending upon the transmittance of a sheet or sheets in the sheet path generates an output signal when there is a multiple sheet condition.
  • the circuit may be calibrated for varying circuit parameters to accommodate different sheet weights and types.
  • PATENTEWAT 6 I975 SHEET R 0F 4 mwnn .Euxm mjuzm f v at All! NEE.
  • This invention relates to a multiple sheet detection system to detect the presence of superposed sheets advanced along a sheet path and to indicate to a machine control that a multiple sheet feed condition has occurred.
  • the detection system of the invention is accomplished by comparing the light transmittance of each fed sheet with that of a sample sheet and utilizing an electronic circuit for comparing differences of the transmissions and generating appropriate signals to machine control to indicate the presence of superposed sheets.
  • FIG. 1 illustrates schematically a xerographic record ing apparatus incorporating a multiple sheet detection system constructed in accordance with the present invention
  • FIG. 2 is an enlarged view of the sheet detection station of the apparatus illustrating the illumination assembly and the detector photosensor assembly of the present invention and their relationship to the sheet feed path;
  • FIG. 2A is a partial end view of the detection station of FIG. 2 illustrating details of the illumination assembly and the detector and sample sheet photosensor assemblies;
  • FIG. 3 is a circuit diagram of the multiple sheet detection system
  • v FIG. 4 is a diagram illustrating signal voltage variations indicative of single and multiple sheet feed conditions.
  • FIG. 1 there is shown various components of a xerographic recording machine which produces enlarged copies of microfilm aperture cards on cut sheets of different sizes and weights at high rates and which utilizes a multiple sheet detection system according to the present invention.
  • a light image of an original to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon.
  • the latent image is developed with an oppositely charged developing material to form a powder image corresponding to the latent image on the plate surface.
  • the powder image is then electrostatically transferred to a support surface such as paper to which it is permanently affixed.
  • aperture cards are placed in a card feed section 16 from which each card is fed in seriatim in a path transverse to the optical path to scan a film frame on the card in timed relation to the movement of a xerographic plate which is in the form of a drum 20.
  • Xerographic drum 20 comprises a layer of photoconductive material on a conductive backing and is mounted in suitable bearings in a machine frame and driven by a suitable drive. The drum passes first a charging station A at which a uniform electrostatic charge is deposited by a corona generating device 21.
  • the drum is exposed to a light image to discharge the photoconductive layer in the areas struck by light whereby there remains on the drum a latent electrostatic image corresponding to the film frame on the aperture card being scanned.
  • the electrostatic latent image passes through a development station C at which a developing material including toner particles having electrostatic charge opposite to that of the electrostatic latent image are cascaded across the drum surface whereby the toner particles adhere to the latent image to form a powdered image.
  • additional toner particles are supplied to the developing material in proportion to the amount of toner deposited on the drum.
  • an image transfer station D Positioned adjacent to the development station C is an image transfer station D at which the powder images are electrostatically transferred from the drum surface to sheet material supplied from a sheet feed station past a sheet detection station in a manner as will be explained more fully hereinafter.
  • a sheet transport apparatus serves to transport the sheet material received from a sheet feed section 27 toward a transfer station D where a corona transfer device 29 similar to the corona charging device 21 is located to affect the electrostatic transfer of the developed image onto the sheet material.
  • the powder image is permanently affixed to the sheet material by a heat fuser apparatus 31 and the sheet material conveyed onto a vertical transport 33 for delivery to a copy tray 35.
  • a drum cleaning station E comprises a corona discharge device 37 and brush 39 to remove residual toner particles remaining on the drum surface after image transfer, and a light source 40 to complete discharge of any residual electrostatic charge remaining on the surface whereby the drum may be ready for another cycle to pass through the processing stations as just described.
  • FIG. 2 there is shown a sheet detection station located at the exit side of sheet feed section 27 which feeds sheets of different sizes and/or types as selected from a conveniently located control panel. Sheets are fed desirably one at a time toward guide members 45 which converge and terminate at the exit of the sheet feed sections where the multiple sheet detection station is positioned.
  • the sheet feed section is modular and is of the type which can be easily pulled away from the rest of the xerographic recording machine as described more fully in the previously mentioned copending applications.
  • I1- lumination assembly 51 includes a source of illumination DSl which may be an incandescent lamp or other suitable light source in a housing 57 formed with an aperture 59 and an aperture 61 such that illumination can be sensed in two directions (FIG. 2A).
  • a photosensitive element V1 receives illumination through an aperture 62 located in a housing 63 and photosensitive element V2 receives illumination through an aperture 64 in a housing 65.
  • Photosensitive elements V1 and V2 may be any suitable light sensitive device.
  • the photosensitive element may include a photocell, photovoltaic, photoconductor, phototransistor, photodiode, etc. It is preferred to use a cadmium sulfide or cadmium selenide photocell due to their increased sensitivity.
  • Guide members 45 are notched or opened to provide an uninterrupted flow of illumination in a direction across the sheet path.
  • Mounted on housing 57 is a leaf spring member 66 which is adapted to hold a smaple sheet portion S in overlying relation to aperture 61 (FIG. 2A).
  • Source ofillumination D51 is adjustable relative to the housing as by screws 67 received in the housing against the action of springs 68. It will be appreciated that the overall configuration of the source of illumination and its apertures and the photosensitive elements and their apertures is such that any variation in sensitivity due to differences in the sheet path is minimized.
  • illumination from DSl is interrupted in the direction of photosensitive element V1 which causes an increase in the resistance of this element while photosensitive element V2 remains unaffected.
  • the photosensitive elements are coupled to an electronic circuit which produces an output signal to machine control as will be described hereinafter.
  • the photosensitive element resistance level normally generated by advancing single sheets is such as to be the same or nearly the same as the light transmission of sample sheet portion S.
  • the drop in light transmission causes the resistance of photosensitive element V1 to increase significantly above that of V2.
  • the electronic circuit coupled to the photosensitive elements utilizes this resistance change to generate an output signal to a machine control to indicate the presence of multiple sheets.
  • the circuit has a regulated, well filtered power supply which is made up of a transformer T1, bridge rectifier CR1, resistors R1, R2 and R3, capacitors C1 and C2 and zener diodes CR2 and CR3. It has been found that output voltages from such a power supply of about plus and minus 12 volts performs well for purposes of the present invention.
  • Transformer T1 also provides a supply voltage for source of illumination DSl.
  • a resistor R11 is used to provide an unfiltered power source for a relay Kl which is energized in a manner to be described hereinafter.
  • Photosensitive element V1, a trim pot R6 and a resistor R7 serve to make up a voltage divider for sensing.
  • a single sheet is positioned at the detection station and trim pot R6 is adjusted to establish a voltage at point A of about one half the normal supply voltage which in this case is 6 volts.
  • photosensitive element V2, a trim pot R14, a trim pot R4 and a potentiometer R36 make up a voltage divider which generates an output representative of the light transmittance of sample sheet portion S.
  • a resistor R15 provides a low resistance path around photosensitive element V2, trim pot R4, and potentiometer R36.
  • trim pot R14 is adjusted to establish a suitable offset voltage y between point C and point D.
  • Offset voltage y should not be too low so that a dense single sheet will actuate the detection system to indicate a double sheet condition or so high that very light or high transmittance superposed sheets being fed past the detecting station do not indicate a single sheet condition.
  • an offset voltage y is desirable which ranges from about 0.5 volts to about 2 volts and preferably about 1.2 volts (FIG. 4).
  • point A is connected to the negative input of a differential amplifier Q1.
  • point B is connected to the positive input of differential amplifier Q1.
  • Q When point B goes positive with respect to point A, Q] will be turned on which in turn will cause transistor G2 to turn on which drives a relay Kl coupled to machine control.
  • the voltage at point B goes positive with respect to the voltage at point A when a multiple sheet feed condition occurs at the sheet detection station causing Q1 and ()2 to be turned on and relay Kl to be actuated.
  • Relay Kl energizes'a suitable indicator for the multiple sheet condition and/or deenergizes the machine processor before a malfunction can occur.
  • the system is adapted for calibration to meet such varying conditions.
  • a calibration switch S38 is provided to be manually actuated during the time that a single sheet of the material of the type to be fed is introduced at the detection station.
  • Switch S38 is held actuated until such time as potentiometer R36 can be adjusted to turn on Q1 for the most dense sheet to be fed or when point B is about 1.2 volts negative with respect to point A.
  • potentiometer R36 can be adjusted to turn on Q1 for the most dense sheet to be fed or when point B is about 1.2 volts negative with respect to point A.
  • a resistor R and a zener diode CR4 are provided to indicate multiple sheets are present if illumination source DSl fails.
  • Q1 will turn on when illumination ceases thereby providing a fail-safe operation.
  • the invention described above enables multiple sheets to be detected in a rapid and simple manner without sacrificing reliability.
  • the detection system is error free since a balanced condition is maintained in the circuitry despite aging of the illumination assembly or response of the photosensor assemblies.
  • the detection system combines a stability of performance with speed of operation.
  • the great latitude of sheet weights and types that can be accommodated in the system of the invention is highly desirable. It will be appreciated that the sheet detection system of the invention is useful in environments such as the present day copier/duplicator machines.
  • an improved detection apparatus for detecting multiple superposed sheets at a sheet detection station comprising means for feeding sheet material along a sheet path past copy processing stations.
  • first photosensitive means for receiving illumination from said illumination means
  • first circuit means for generating discrete electrical signals representative of the transmittance of sheet material to be detected
  • third circuit means for comparing the signals generated from said first and second circuit means and determining the presence of multiple superposed sheets and generating an output signal to machine control to de-energize the machine when a multiple superposed sheet condition occurs at the sheet detection station, and

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Controlling Sheets Or Webs (AREA)
  • Paper Feeding For Electrophotography (AREA)
US025804A 1970-04-06 1970-04-06 Detection system for superposed sheets Expired - Lifetime US3882308A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US025804A US3882308A (en) 1970-04-06 1970-04-06 Detection system for superposed sheets
CA096298A CA929632A (en) 1970-04-06 1970-10-22 Detection system for superposed sheets
DE19712116802 DE2116802A1 (enrdf_load_stackoverflow) 1970-04-06 1971-04-17
GB2601071*A GB1342838A (en) 1970-04-06 1971-04-19 Detection system for superposed sheets

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US025804A US3882308A (en) 1970-04-06 1970-04-06 Detection system for superposed sheets

Publications (1)

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US3882308A true US3882308A (en) 1975-05-06

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US025804A Expired - Lifetime US3882308A (en) 1970-04-06 1970-04-06 Detection system for superposed sheets

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US (1) US3882308A (enrdf_load_stackoverflow)
CA (1) CA929632A (enrdf_load_stackoverflow)
DE (1) DE2116802A1 (enrdf_load_stackoverflow)
GB (1) GB1342838A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4511904A (en) * 1982-10-18 1985-04-16 Tokyo Shibaura Denki Kabushiki Kaisha Recording apparatus
US4540887A (en) * 1983-01-28 1985-09-10 Xerox Corporation High contrast ratio paper sensor
US4577096A (en) * 1983-08-15 1986-03-18 Xerox Corporation Multiple copy and transparency detector with illumination control
US4831273A (en) * 1987-10-29 1989-05-16 Pitney Bowes Inc. Mailing machine sensing device
US5146087A (en) * 1991-07-23 1992-09-08 Xerox Corporation Imaging process with infrared sensitive transparent receiver sheets
EP0888991A3 (en) * 1997-07-02 1999-06-02 Riso Kagaku Corporation Multiple feed detecting system
EP1081074B1 (en) * 1999-08-31 2004-04-07 Riso Kagaku Corporation Method and device for detecting multiple feed

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3270835D1 (en) * 1982-03-01 1986-06-05 Christian Pierre Bourg Sheet collator
DE3230524C2 (de) * 1982-08-17 1987-04-09 Agfa-Gevaert Ag, 5090 Leverkusen Einrichtung zum Erkennen von zwei oder mehreren Übereinanderliegenden Filmblättern
GB2194040A (en) * 1986-07-23 1988-02-24 Ratby Eng Co Ltd Paper feed control apparatus
GB8629209D0 (en) * 1986-12-05 1987-01-14 Smiths Industries Plc Control means

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2512247A (en) * 1946-08-07 1950-06-20 X Ray Electronic Corp Antimagnetically shielded photocell
US2517330A (en) * 1949-09-07 1950-08-01 Johns Manville Apparatus for measuring the thickness of semiopaque material
US2646556A (en) * 1950-06-17 1953-07-21 C O Two Fire Equipment Co Supervised alarm system
US3026419A (en) * 1959-05-11 1962-03-20 Ibm Overlap detector
US3372276A (en) * 1965-05-21 1968-03-05 Atomic Energy Commission Usa Method and system for the non-destructive inspection of variable density plates

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2512247A (en) * 1946-08-07 1950-06-20 X Ray Electronic Corp Antimagnetically shielded photocell
US2517330A (en) * 1949-09-07 1950-08-01 Johns Manville Apparatus for measuring the thickness of semiopaque material
US2646556A (en) * 1950-06-17 1953-07-21 C O Two Fire Equipment Co Supervised alarm system
US3026419A (en) * 1959-05-11 1962-03-20 Ibm Overlap detector
US3372276A (en) * 1965-05-21 1968-03-05 Atomic Energy Commission Usa Method and system for the non-destructive inspection of variable density plates

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4511904A (en) * 1982-10-18 1985-04-16 Tokyo Shibaura Denki Kabushiki Kaisha Recording apparatus
US4540887A (en) * 1983-01-28 1985-09-10 Xerox Corporation High contrast ratio paper sensor
US4577096A (en) * 1983-08-15 1986-03-18 Xerox Corporation Multiple copy and transparency detector with illumination control
US4831273A (en) * 1987-10-29 1989-05-16 Pitney Bowes Inc. Mailing machine sensing device
US5146087A (en) * 1991-07-23 1992-09-08 Xerox Corporation Imaging process with infrared sensitive transparent receiver sheets
EP0888991A3 (en) * 1997-07-02 1999-06-02 Riso Kagaku Corporation Multiple feed detecting system
US6053495A (en) * 1997-07-02 2000-04-25 Riso Kagaku Corporation Multiple feed detecting system
EP1081074B1 (en) * 1999-08-31 2004-04-07 Riso Kagaku Corporation Method and device for detecting multiple feed

Also Published As

Publication number Publication date
DE2116802A1 (enrdf_load_stackoverflow) 1971-10-21
GB1342838A (en) 1974-01-03
CA929632A (en) 1973-07-03

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