US3805739A - Controlling multiple voltage levels for electrostatic printing - Google Patents

Controlling multiple voltage levels for electrostatic printing Download PDF

Info

Publication number
US3805739A
US3805739A US00152138A US15213871A US3805739A US 3805739 A US3805739 A US 3805739A US 00152138 A US00152138 A US 00152138A US 15213871 A US15213871 A US 15213871A US 3805739 A US3805739 A US 3805739A
Authority
US
United States
Prior art keywords
magnetic brush
normal mode
machine
developing
circuit
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
US00152138A
Other languages
English (en)
Inventor
R Feldeisen
M Stanley
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
Priority to US00152138A priority Critical patent/US3805739A/en
Priority to CA141,954A priority patent/CA972552A/en
Priority to DE2227709A priority patent/DE2227709C3/de
Priority to GB2675672A priority patent/GB1382710A/en
Priority to NLAANVRAGE7207843,A priority patent/NL170893C/xx
Application granted granted Critical
Publication of US3805739A publication Critical patent/US3805739A/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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G03G15/0907—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush with bias voltage

Definitions

  • ABSTRACT An electrical arrangement associated with the control and operating circuitry for an electrostatic printing machine of the type employing magnetic brush development for controlling the electrical bias on the developing magnetic brushes for enhancing print quality in situations wherein the background or density of an original to be copied is unsuitable for normal mode printing. Along with normal mode printing, there is provided means for biasing the magnetic brushes for originals having dark background or are of low density.
  • coao TRON SOURCE OSCILLATOR 30 CONTROLLING MULTIPLE VOLTAGE LEVELS FOR ELECTROSTATIC PRINTING
  • This invention relates to electrostatic printing machines, and in particular, to a control arrangement of voltage supplies for providing developing bias in accordance with the illumination characteristics of an original to be copied.
  • Electrostatic printing machines of the type employing an illumination system for illuminating an original generally are encumbered by an inability to present image rays for imaging purposes of sufficient depth or contrast asto produce properly an electrostatic latent image of usable condition for all possible input originals.
  • an original may have a dark or colored background and when exposed there results a la tent image having charged and discharged areas both with high charge levels of very close values. When developed, the image will include intolerable amounts of background development.
  • the original is of the low density type, there usually results image areas almost completely washed out, so to speak.
  • the principal object of the present invention is to improve electrostatic printing machines of the type employing magnetic brush development.
  • Another object of the present invention is to improve image quality obtainable from electrostatic printing for originals which in themselves have very poor irradiance characteristics.
  • an arrangement of electrical circuitry and control devices which are adapted to be preset for originals which are classified as different for controlling energization of the development bias on the magnetic brushes utilized in the printing machine.
  • This control of energization is in the form of connecting the brushes to voltage sources of different voltage levels thereby producing an electric field between the brushes and an electrostatic latent image in accordance with the need for the particular level so supplied.
  • the control arrangement may also be associated with other processing devices in the printing machines in order to control their operation in the enhancement of print quality.
  • FIG. 1 is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention.
  • FIG. 2 is a schematic representation of a control arrangement associated with some of the processing devices in the machine.
  • FIG. 1 For a general understanding of the illustrated copier/reproduction machine, in which the invention may be incorporated, reference is had to FIG. 1 in which the various system components for the machine are schematically illustrated.
  • a light image of a document 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 xerographic powder image, corresponding to the latent image on the plate surface.
  • the powder image is then electrostatically transferred to a support surface to which it may be fused by a fusing device whereby the powder image is caused permanently to adhere to the support surface.
  • an original D to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly generally indicated by the reference numeral 10, arranged at the left end of the machine. While upon the platen, an illumination system flashes light rays upon the original thereby producing image rays corresponding to the information areas on the original.
  • the image rays are projected by means of an optical system for exposing the photosensitive surface of xerographic plate in the form of a flexible photoconductive belt 12 arranged on a belt assembly generally indicated by the reference numeral 114.
  • the photoconductive belt ssembly 14 is slidably mounted upon two support shafts one of which is secured to the frame of the machine and is adapted to drive the belt 12 in the direction of the arrow at a constant rate. During this movement of the belt, the reflected light image of the original D on the platen is flashed upon the photoreceptor surface of the belt to produce electrostatic latent images thereon at an exposure station A.
  • the electrostatic image passes through a developing station B in which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple magnetic brushes as the same moves through the development Zone.
  • the developed electrostatic image is transported by the belt to a transfer station C whereat a sheet of copy paper is moved between a transfer roller and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by an electrical bias on the transfer roller.
  • a sheet transport mechanism generally indicated at 16 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeral 17 to the developed image on the belt at the station C.
  • the sheet After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly generally indicated by the reference numeral 18 wherein the developed and transferred xerographic powder image on the sheet material is permanently affixed thereto. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus.
  • the belt 12 comprises a photoconductive layer of selenium which is the light receiving surface and imaging medium for the apparatus, on a conductive backing.
  • the belt is journaled for continuous movement upon three rollers 20, 21 and 22 located with parallel axes at approximately the apex of a triangle. During exposure of the belt 12, the portion thereof being exposed is that part of the belt run between the roller 20 and the lower roller 21.
  • the upper roller 22 is rotatably supported on a hollow shaft 23 which is rotatably driven by a suitable motor and drive (not shown) mounted in the machine. Further details regarding the structure of the belt assembly 14 and its relationship with the machine and support therefor may be found in the copending application Ser. No. 102,312 assigned to the same assignee.
  • the electrostatic printing machine employs magnetic brush development, utilizing a plurality of magnetic brushes 25, which span across the development zone B.
  • the brushes are mounted for rotation on shafts 26 each of which is electrically connected to a bus bar 27 by suitable conductive brush elements 28.
  • a magnetic brush it is desirable, for development quality and completeness, that a magnetic brush have associated therewith an electric field between it and a latent image being developed.
  • the combination of magnetic flux lines and electric field lines enhances development, provides for solid area coverage and permits control of the uniform application of toner particles to image areas and the minimization of toner deposition in background areas.
  • the illustrated electrostatic machine also includes a pre-transfer corona generating device or corotron 30 which, when energized with an a.c. potential at a predetermined level, serves to modify to some degree, d.c. toner charges on the photoreceptor surface of the belt 12 after development and before the transfer of the developed image on the belt 12 to a sheet of paper at the transfer station C.
  • This application of an a.c. current reduces the level of the potential of the image area so that the potential of the transfer voltage necessary to effect the transfer of toner particles from the developed image areas to the paper may be lessened.
  • this lessening of the transfer voltage lessens the electrostatic forces holding the sheet upon the biased transfer roller 31 making strip-off of the sheet an easier operation.
  • the pretransfer corotron lessens the electrostatic force variability between the sheet and the photoreceptor surface thus making strip-off more reliable for a wide range of images.
  • FIG. 2 there is shown a control system incorporating electrical circuitry associated with the machine described above.
  • the bus bar 27 is electrically connected to a terminal 32, which in turn is connected to an electrical power supply generally indicated in FIG. 1 by the numeral 33.
  • the bus bar is connected to a voltage source 34 as shown in FIG. 2 which is incorporated in the power supply 33 suitably connected to line voltage for the machine.
  • This circuit including the source 34 is indicative of one provided on electrostatic machines employing magnetic brushes for development purposes.
  • This circuit supplies development bias to the terminal 32 and to each of the magnetic brushes for the general all around use of the machine.
  • Incorporated into this basic circuit in order to provide for development of originals which are either too dark in overall format or of low density, both conditions being beyond the capabilities of normal electrostatic reproduction, are various control devices for aiding in the reproduction of the originals so conditioned.
  • the general power supply also includes two additional voltage sources 35, 36 which are adapted to be connected to the terminal 32.
  • the source 34 is utilized and is connected to the bus bar by way of two normally closed relay switch contacts 1K2 and 2K1. Therefore, in the normal mode of machine operation, when the machine is in print condition, the magnetic brushes 25 are energized with a developing bias supplied by the voltage source 34.
  • the bias in normal mode operation is 200 volts.
  • the voltage source 35 is electrically connected to the bus bar by closing the normally open relay switch contact 1K1 and the normally closed relay contact 2K1 and the source 36 is electrically connected to the bus bar by way of the normally open relay switch contact 2K2.
  • Actuation of the contacts 1K2 and 2K1 to open positions and the switches 1K1 and 2K2 to closed positions is obtained by means of the two relays 1K and 2K electrically connected for energization thereof by the machine logic 40 and a suitable voltage supply 41 therefor.
  • Associated with the relay 1K for controlling energization thereof is a manually actuable switch 42 suitably mounted on the control panel for the machine.
  • the relay 2K is adapted to be energized upon manual actuation of another switch 43 also suitably mounted on the control panel.
  • This energization actuates the contact 1K1 to a closed condition and the contact 1K2 to an open position.
  • the source 35 is adapted to'supply 400 volts to the bus bar.
  • a development bias of approximately twice the amount as normally used can be applied.
  • the development bias be less than normal since the image contrast level remaining on the photoreceptor belt after exposure is lower than adequate for normal development.
  • the machine operator before commencing the printing, will actuate the switch 43, labeled Low Density switch, for connecting the relay 2K to the voltage source 41 thereby energizing this relay.
  • This energization causes the opening of the contact 2K1 for disconnecting the magnetic brushes from either of the two voltage sources 34, 35 and the closing of the contact 2K2 for connecting the low voltage source 36 directly to the brushes.
  • the voltage supplied by the source 36 may be in the neighborhood of 100 volts.
  • the switches 42, 43 may be arranged so that actuation of one to a closed condition, opens the other and when the machine is in normal mode operation, both switches 42, 43 assume a non-actuated state.
  • the low density control relay 2K is also adapted to actuate a normally closed relay switch contact 2K3 to an open position for effecting the deenergization of the pretransfer corotron 30.
  • the corotron is connected to an ac. oscillator 45 to be energized thereby producing a.c. corona upon the photoreceptor belt before a developed image is moved into the transfer position C.
  • the pre-transfer corotron is utilized to neutralize or reduce the charge on the image and background areas in order to lessen the variations due to images necessary for effecting the transfer of a developed image to a sheet of paper at the transfer station.
  • the neutralizing effects of the pre-transfer corotron may further reduce or even eliminate the contrast characteristics of the image as presented to the transfer station. To preclude this from occurring, the low contrast images that have been enhanced by the low development bias are preserved for transfer by turning off the pre-transfer corotron. For the parameters chosen by way of illustration, better results have been obtained with the pre-transfer corotron deenergized when the low density switch 43 is actuated.
  • the invention contemplates the selective use of three voltage potentials for development control, depending upon the mode of machine operation; that is, in the normal mode, for the reproduction of originals of dark or colored background, or for the reproduction of originals of low density information. Coupled with the latter mode is the choice of utilizing the control of pretransfer conditions. This selective use enables the reproduction of originals not otherwise available in printing machines which operate in the conventional normal mode.
  • An electrostatic printing machine having a photoconductive member movable relative to a developing zone, a magnetic brush developing device for develop ing electrostatic latent images on the member and normal mode circuit means for establishing an electric field of predetermined electrical potential between the magnetic brush device and the latent image during development of the same comprising a first circuit including a voltage source of a potential higher than said predetermined potential,
  • control means associated with said circuits for selectively connecting one of said circuits or said normal mode circuit means to the magnetic brush device thereby impressing one of three potentials between the magnetic brush device and the latent image.
  • the normal mode circuit means includes a normally closed switch for normally supplying the magnetic brush device with electrical potential.
  • said first circuit includes a normally open switch between the voltage source associated therewith and the magnetic brush device and also includes means for opening said normally closed switch and for closing said normally open switch thereby effectively opening the circuit of the normal mode circuit means and closing said first circuit.
  • An electrostatic printing machine having a photoconductive member movable relative to a developing zone, means for uniformly charging the member, a magnetic brush developing device for developing electrostatic latent images on the member, means for transferring a developed image from the member to the support material, and an electrical energizing device adapted to neutralize some of the charges on the developed image prior to transfer thereof comprising,

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Developing For Electrophotography (AREA)
  • Color Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
US00152138A 1971-06-11 1971-06-11 Controlling multiple voltage levels for electrostatic printing Expired - Lifetime US3805739A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US00152138A US3805739A (en) 1971-06-11 1971-06-11 Controlling multiple voltage levels for electrostatic printing
CA141,954A CA972552A (en) 1971-06-11 1972-05-12 Controlling multiple voltage levels for electrostatic printing
DE2227709A DE2227709C3 (de) 1971-06-11 1972-06-07 Elektrostatische Kopiermaschine
GB2675672A GB1382710A (en) 1971-06-11 1972-06-08 Electrostatic printing machine
NLAANVRAGE7207843,A NL170893C (nl) 1971-06-11 1972-06-09 Elektrostatische afdrukinrichting.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00152138A US3805739A (en) 1971-06-11 1971-06-11 Controlling multiple voltage levels for electrostatic printing

Publications (1)

Publication Number Publication Date
US3805739A true US3805739A (en) 1974-04-23

Family

ID=22541663

Family Applications (1)

Application Number Title Priority Date Filing Date
US00152138A Expired - Lifetime US3805739A (en) 1971-06-11 1971-06-11 Controlling multiple voltage levels for electrostatic printing

Country Status (5)

Country Link
US (1) US3805739A (de)
CA (1) CA972552A (de)
DE (1) DE2227709C3 (de)
GB (1) GB1382710A (de)
NL (1) NL170893C (de)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901189A (en) * 1974-01-28 1975-08-26 Xerox Corp Magnetic brush developing apparatus
US3927641A (en) * 1973-05-10 1975-12-23 Fuji Xerox Co Ltd Developing mechanism using magnetic brush
US3981268A (en) * 1975-06-11 1976-09-21 Fuji Xerox Co., Ltd. Device for controlling electric potential applied to developing electrode in an electrophotographic duplicator
US3996892A (en) * 1975-02-24 1976-12-14 Xerox Corporation Spatially programmable electrode-type roll for electrostatographic processors and the like
US4149487A (en) * 1977-08-30 1979-04-17 Xerox Corporation Xerographic machine with infinitely variable developer bias
DE2900765A1 (de) * 1978-01-17 1979-07-19 Konishiroku Photo Ind Vorspannung-schaltkreis zur regelung der bilddichte bei einem kopiergeraet
DE2901086A1 (de) * 1978-01-17 1979-07-19 Konishiroku Photo Ind Vorrichtung zur regelung der dichte eines kopierbilds
US4482243A (en) * 1981-09-08 1984-11-13 Canon Kabushiki Kaisha Image formation apparatus
US4496644A (en) * 1983-02-28 1985-01-29 Eastman Kodak Company Electric field adjustment for magnetic brushes
US4500198A (en) * 1982-12-10 1985-02-19 International Business Machines Corporation Multiple roller magnetic brush developer having development electrode voltage switching
US4529293A (en) * 1982-03-02 1985-07-16 Oce-Nederland B.V. Electrophotographic copying process and machine
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US4714942A (en) * 1985-06-18 1987-12-22 Fujitsu Limited Reversal image development type electrophotographic printing system
US4755850A (en) * 1981-01-13 1988-07-05 Canon Kabushiki Kaisha Electrostatic recording apparatus including a controlled developer device

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037478A (en) * 1957-10-23 1962-06-05 American Photocopy Equip Co Apparatus for developing electrophotographic sheet
US3152012A (en) * 1960-12-19 1964-10-06 Ibm Apparatus for the development of electrostatic images
US3185051A (en) * 1962-10-16 1965-05-25 Xerox Corp Xerographic method
US3219014A (en) * 1962-12-04 1965-11-23 Xerox Corp Mechanical shield to protect magnetic core in xerographic developing apparatus
US3328193A (en) * 1962-10-02 1967-06-27 Australia Res Lab Method of and means for the transfer of images
US3368894A (en) * 1963-11-05 1968-02-13 Australia Res Lab Multiple copy printing method and apparatus
US3654893A (en) * 1970-05-01 1972-04-11 Eastman Kodak Co Automatic bias control for electrostatic development

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2890968A (en) * 1955-06-02 1959-06-16 Rca Corp Electrostatic printing process and developer composition therefor

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037478A (en) * 1957-10-23 1962-06-05 American Photocopy Equip Co Apparatus for developing electrophotographic sheet
US3152012A (en) * 1960-12-19 1964-10-06 Ibm Apparatus for the development of electrostatic images
US3328193A (en) * 1962-10-02 1967-06-27 Australia Res Lab Method of and means for the transfer of images
US3185051A (en) * 1962-10-16 1965-05-25 Xerox Corp Xerographic method
US3219014A (en) * 1962-12-04 1965-11-23 Xerox Corp Mechanical shield to protect magnetic core in xerographic developing apparatus
US3368894A (en) * 1963-11-05 1968-02-13 Australia Res Lab Multiple copy printing method and apparatus
US3654893A (en) * 1970-05-01 1972-04-11 Eastman Kodak Co Automatic bias control for electrostatic development

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3927641A (en) * 1973-05-10 1975-12-23 Fuji Xerox Co Ltd Developing mechanism using magnetic brush
US3901189A (en) * 1974-01-28 1975-08-26 Xerox Corp Magnetic brush developing apparatus
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US3996892A (en) * 1975-02-24 1976-12-14 Xerox Corporation Spatially programmable electrode-type roll for electrostatographic processors and the like
US3981268A (en) * 1975-06-11 1976-09-21 Fuji Xerox Co., Ltd. Device for controlling electric potential applied to developing electrode in an electrophotographic duplicator
US4149487A (en) * 1977-08-30 1979-04-17 Xerox Corporation Xerographic machine with infinitely variable developer bias
DE2901086A1 (de) * 1978-01-17 1979-07-19 Konishiroku Photo Ind Vorrichtung zur regelung der dichte eines kopierbilds
US4213692A (en) * 1978-01-17 1980-07-22 Konishiroku Photo Industry Co., Ltd. Bias voltage switching circuit for controlling concentration of image in copying apparatus
DE2900765A1 (de) * 1978-01-17 1979-07-19 Konishiroku Photo Ind Vorspannung-schaltkreis zur regelung der bilddichte bei einem kopiergeraet
US4755850A (en) * 1981-01-13 1988-07-05 Canon Kabushiki Kaisha Electrostatic recording apparatus including a controlled developer device
US4482243A (en) * 1981-09-08 1984-11-13 Canon Kabushiki Kaisha Image formation apparatus
US4529293A (en) * 1982-03-02 1985-07-16 Oce-Nederland B.V. Electrophotographic copying process and machine
US4500198A (en) * 1982-12-10 1985-02-19 International Business Machines Corporation Multiple roller magnetic brush developer having development electrode voltage switching
US4496644A (en) * 1983-02-28 1985-01-29 Eastman Kodak Company Electric field adjustment for magnetic brushes
US4714942A (en) * 1985-06-18 1987-12-22 Fujitsu Limited Reversal image development type electrophotographic printing system

Also Published As

Publication number Publication date
NL7207843A (de) 1972-12-13
DE2227709C3 (de) 1981-09-17
NL170893C (nl) 1983-01-03
DE2227709B2 (de) 1981-01-29
DE2227709A1 (de) 1972-12-28
NL170893B (nl) 1982-08-02
GB1382710A (en) 1975-02-05
CA972552A (en) 1975-08-12

Similar Documents

Publication Publication Date Title
US3847478A (en) Segmented bias roll
US3837741A (en) Control arrangement for transfer roll power supply
US3775102A (en) Method of electrostatically copying information on both sides of an original onto both sides of a support material
US2901374A (en) Development of electrostatic image and apparatus therefor
US3697171A (en) Simultaneous image transfer
US3805739A (en) Controlling multiple voltage levels for electrostatic printing
US4811046A (en) Tri-level highlight color printing apparatus with cycle-up and cycle-down control
US5019859A (en) Process control for highlight color with developer switching
US4761672A (en) Ramped developer biases
US3531195A (en) Method and apparatus for multicolor printing
US3520604A (en) Photoelectrostatic copier
US3685896A (en) Duplicating method and apparatus
US4039257A (en) Pretransfer corotron switching
US3809472A (en) Pre-development exposure assembly
US3592642A (en) Duplicating method wherein a paper sheet heated to the melting point of a toner image simultaneously causes the transfer of the toner from the photoconductor and fusing of the toner image on the paper sheet
JPS593461A (ja) エレクトログラフイツク映像装置
US3820777A (en) Elevator assembly positioning control
US3743403A (en) Transport assembly
US3751155A (en) Pre-development exposure assembly
US3806242A (en) Apparatus for regulating the operation of a device in accordance with the supply of material upon which the device operates
US5038177A (en) Selective pre-transfer corona transfer with light treatment for tri-level xerography
US4027960A (en) Transfer system for electrostatic reproduction machine
US4087169A (en) Transfer roller system
JPH08334947A (ja) ５サイクルのカラー像印刷方法
US4984021A (en) Photoreceptor edge erase system for tri-level xerography