US3332396A - Xerographic developing apparatus with controlled corona means - Google Patents

Xerographic developing apparatus with controlled corona means Download PDF

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Publication number
US3332396A
US3332396A US328984A US32898463A US3332396A US 3332396 A US3332396 A US 3332396A US 328984 A US328984 A US 328984A US 32898463 A US32898463 A US 32898463A US 3332396 A US3332396 A US 3332396A
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US
United States
Prior art keywords
corona
donor
web
development
xerographic
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
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US328984A
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English (en)
Inventor
Robert W Gundlach
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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 US328984A priority Critical patent/US3332396A/en
Priority claimed from US328934A external-priority patent/US3171619A/en
Priority to GB4860364A priority patent/GB1060679A/en
Priority to DE1964R0039391 priority patent/DE1288915B/de
Priority to FR997869A priority patent/FR1419973A/fr
Priority to BE656893A priority patent/BE656893A/xx
Application granted granted Critical
Publication of US3332396A publication Critical patent/US3332396A/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
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/28—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning
    • G03G15/30—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning in which projection is formed on a drum
    • 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
    • G03G15/0806—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller
    • G03G15/081—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller characterised by the developer handling means after the supply and before the regulating, e.g. means for preventing developer blocking
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • a xerographic plate comprising a layer of photoconductive insulating material on a conductive backing is given a uniform electric charge over its surface and is then exposed to the subject matter to be reproduced usually by convention projection techniques. This exposure discharges the plate areas in accordance with the radiation intensity that reaches it, and thereby creates an electrostatic latent image on or in the photoconductive layer. Development of the latent image is effected with an electrostatically charged, finely divided material such as an electroscopic powder, that is brought into surface contact with the photoconductive layer and is held thereon electrostatically in a pattern corresponding to the electrostatic latent image.
  • an electrostatically charged, finely divided material such as an electroscopic powder
  • the developed image may be fixed by any suitable means to the surface on which it has been developed or may be transferred to a secondary support surface to which it may be fixed or utilized by means known in the art.
  • a support member such as a web, sheet or other member termed a donor which carries a releasable layer of electroscopic marking particles to be presented into close contact with an image-bearing plate for deposit in conformity with the electrostatic image to be developed.
  • donor development the electrical properties of the donor member are a factor for developing in response to the area characteristics of the latent image. That is, electrically insulating donors respond best with line copy while electrically conductive donors respond best with solid areas in a manner comparable to the control electrode. Accordingly, prior attempts to provide development flexibility on a practical basis for development of any kind of image such as solid area versus line copy, with the system of Mayo has not met with success. This has resulted in limitations on the usual copying system since material to be reproduced cannot be copied in random order.
  • novel method and apparatus adapted to afford control over development properties in accordance with the area characteristics of the latent image to be developed.
  • control is achieved by employing a donor member having electrical resistivity able to support charge at its top surface for a time compatible with the speed at which the donor is moved.
  • a corona discharge is applied against the back side of its presentation area to maintain equal potential as it moves through area-s of varying fields against the plate surface.
  • FIG. 1 is a schematic illustration of a continuously operative automatic xerographic apparatus incorporating an embodiment of the invention
  • FIG. 2 is an embodiment of the invention as adapted partially for hand operation
  • FIG. 3 is an embodiment of the invention adapted for automatic operation
  • FIGS. 4 and 5 are variations of the embodiments of FIG. 3.
  • a xerographic plate 10 comprising a supporting substrate 11 supporting a layer of photoconductive insulating material 12.
  • Support member 11 is generally and preferably an electrical conductor or a supported electrically conductive layer in contact with photoconductive insulating layer 12. It may thus comprise, in accordance with conventional xerographic usage, such material as aluminum, brass, or other metals, metalized paper or paper with a relatively high moisture content, glass with a transparent or other conductive coating, or like known layer.
  • Photoconductive insulating layer 12 may comprise various photoconductive insulating materials known to be useful in the art of xerography.
  • Such materials preferably include vitreous layers such as selenium, sulfur or anthracene or other organic photoconductors as well as dispersions or photoconductive pigments such as zinc oxide and various resins or other electrically insulating binder mate rials.
  • Layer 12 is generally characterized as being a good electrical insulator capable of maintaining a surface charge in the dark, but becoming substantially more conductive when illuminated by visible light, X-rays, or other forms of activating radiation.
  • layer 12 may be considered to be a layer of vitreous selenium 20 to 50 microns in thickness. Vitreous selenium layers are more fully described in 'Bixby US. Patent 2,970,906.
  • the apparatus includes a xerograph-ic plate 10, in the form of a cylindrical drum, which comprises the photoconductive insulating peripheral surface on a conductive substrate as above.
  • the drum is mounted on an axle 15, journaled for rotation, and driven by a motor 16 through belt 17 connected to pulley 18 secured to the shaft or axle 15.
  • a charging station 20 Position adjacent to the path of motion of the surface of the drum 10 is a charging station 20 comprising, for example a positive polarity corona discharge electrode 21 consisting of a fine wire suitably connected to a high voltage source 22 of potential high enough to cause a corona discharge from the electrode onto the surface of drum 10.
  • an exposure station 23 Subsequent to the charging station 20 in the direction of rotation of the drum, is an exposure station 23 generally comprising suitable means for imposing a radiation pattern reflected or projected from an original copy 24 onto the surface of the xerographic drum.
  • the exposure station is shown to include a projection lens 25 or other exposure mechanism as is conventional in the art, preferably operating with slit projection methods to focus the moving image at the exposure slit 26.
  • a developing station Next subsequent to the exposure station is a developing station, generally designated 30, as will be further described below for rendering the latent image visible.
  • a transfer station 31 adapted to transfer a developed image from the surface of the drum to a transfer web 32 that is advanced from supply roll 33 into contact with the surface of the xerographic drum at a point beneath a transfer electrode 34.
  • the web desirably continues through a fusing or fixing device 35 onto a take-up roll 36 being driven through aslip-clutch arrangement 37 from motor 16.
  • electrode 34 has its corona discharge electrode operably connected to a high voltage source 40 whereby a powder image developed on the surface of the drum is transferred to the web surface.
  • 'Fusing device 35 primarily fixes the transferred powder image onto the web to yield a xerographic print.
  • the xerographic drum 10 continues to rotate past a cleaning station 41 in which residual powder on the drum surface is removed.
  • a cleaning station 41 in which residual powder on the drum surface is removed.
  • This may include, for example, a rotating brush 42 driven by a rotor 43 through a belt 44 whereby the brush bristles bear against the surf-ace of the drum to remove residual developer therefrom.
  • further charging means, illumination means or the like may effect electrical or controlled operations.
  • a donor member 50 Operative at the developing station 30 is a donor member 50 in a form of an endless web, as will be further described, adapted to pass over a pair of insulating rollers 51 and 52 between which developer on the donor member comes into firm surface contact against the surface of the rotating xerographic drum 10. Movement of the donor web is effected by means of a drive roller 54 being driven by a motor 55 operating through a belt 56, preferably to drive the web in the same direction as the surface rotation of the xerographic drum.
  • the speeds of the donor member and drum may be substantially the same or the donor member can travel at surface speeds as high as to times as fast as the peripheral speed of the drum to effect a skidding or sliding action there against. Thus, there is maintained between donor member 50 and drum 10 a continuous contact.
  • a powder loading station Adjacent to one portion of the path of motion of the developer donor member 50 is a powder loading station which may, for example, comprise a developer hopper 57 containing a quantity of developer powder 58 which may be a form of two-component developer mixture as disclosed in Walkup and Wise US. Patent 2,638,416.
  • the hopper opens against the donor member, whereby the web passes in contact with the developer supply and is coacted uniformly with the toner powder component of the mixture as the web passes upwardly against the developer.
  • Other web loading mechanisms and developer compositions may, of course, be employed including dusting, brushing or the like as is known in the art.
  • the donor web in presenting developer to the xerographic plate passes through regions of high and low potential emanating from the charged and uncharged areas of the plate constituting the latent image.
  • the fields associated with the charge pattern extend above the plate surface a distance through which the donor member passes and decreases in magnitude increasingly with distance therefrom.
  • the donor member function in accordance with the invention, it must first be characterized by sufficient strength and durability to be employed for continuous recycling, as were illustrated, and in addition should preferably comprise an electrical insulator or at least possessed of sufficiently high electrical resistance of approximately 10 ohm cm. or greater.
  • a neutral corona bias is applied from corona generating device against the back non-developer bearing surface of the donor member in areas thereof corresponding substantially to the development zone in contact with the xe'rographic plate.
  • the donor surface potential should be reduced with a discharge time constant of about sec. or 20 milliseconds.
  • FIG. 2 there is illustrated a xerographic plate on which an electrostatic latent image has been previously formed and against which a donor member here designated 60, is adapted to be hand-drawn with the developer side in contact against the plate surface.
  • a corona generating device 61 Supported extending from a stand 62 immediately above the donor in the development zone is a corona generating device 61 secured and adapted to be connected to A.C.-D.C. sources 63 and 64 in the manner shown.
  • generating device '61 is mounted as close to the donor surface as feasible being on the order of approximately /s" above the surface thereof.
  • the corona generating potentials are applied to device 61 as by means of a switch not shown.
  • This potential varies somewhat depending on the corona threshold of either polarity for a particular wire electrode diameter. This typically occurs for positive corona at 3000 and 3600- for 2 mil and 3.5 mil wire respectively.
  • the threshold of the same wires for negative corona is approximately 2800 and 3300 volts.
  • an A.C. connection to the wire electrode will inherently produce more negative than positive corona discharge such that the D.C. applied in the circuit thereof serves to equalize the output of both polarities.
  • a neutral or zero voltage results on the backside of the donor member as it is drawn through the development zone.
  • the exact operating conditions will, of course, vary as a function of the relative speeds between donor and xerographic plate as well as particular electrical properties of the donor member being employed. For example, it was found that with a 3 mil thickness baryta paper at relatively dry humidity conditions and toned uniformly with developer, an A.C. supply of 4545 volts with a D.C.
  • two (or more in even multiples) corona generating electrodes here designated 70, 71, 72 and 73 are arranged closely adjacent to each other and staggered as to polarity of corona discharge closely spaced to the rear side of the donor member in contact with the xerographic drum.
  • Each generating device in FIG. 1 is charged to emit a substantially equal output of corona of its respective polarity.
  • FIG. 3 is shown to have similar type electrical connections to the corona generating device 61 as described in connection with FIG. 2 above.
  • FIG. 2 illustrates a partially hand-operated device while FIG. 3 is adapted for automatic operation with the donor web 60 adapted to be driven by motor 73 while the xerographic plate is simul- 6 taneously advanced in the same general direction as the web.
  • FIG. 4 illustrates a variation in which multiple corona generating devices 75 and 76 are each energized with corona generating potential from a D.C. source 77 to achieve an equal potential result similar to that described in connection with FIG. 1.
  • FIG. 5 illustrates a different type of corona generator designated 80 representing a two-wire corona generator, as for example disclosed in Mott US. Patent 3,076,092 in which a D.C. bias is imposed on the center tap of a secondary transformer coil supplying A.C. to alternate electrodes of the corona generator.
  • corona discharge against the backside of a donor member effecting development, it becomes possible to effect results of a ground electrode in enhancing solid area development of xerographic images.
  • the invention is not intended to be limited thereto but is intended to include any of corona generating devices known in the art which alone or in combination can produce the A.C.-D.C. neutralization plane effective in producing the results described above. It is essential that the development zone, being the contact area of donor and plate, be
  • the invention has been described primarily for use with direct development, i.e., developing charge areas on the xerographic plate, by applying a bias approximately equaling the charged areas, and using a developer charged to the same polarity as the charged areas on the xerographic plate, uncharged rather than charged areas will be developed.
  • This latter variation is particularly useful where the original exposure was, for example, from a negative and reversal or indirect development is desired.
  • the uncharged areas may contain solid areas requiring the control electrode effect to obtain good quality development.
  • An electrostatic latent image developing means comprising:
  • (c) means to advance said first surface against the surface of said insulating member
  • corona emitting means comprising a plurality of corona generating electrodes arranged adjacent to each other with alternate electrodes emitting opposite polarity corona of substantially thesame quantity output, said corona emitting means spaced adjacent and at least inch from the second surface of said web at the area of contact between said first surface and said insulating member;
  • An electrostatic latent image developing means comprising:
  • (c) means to advance said first surface against the surface of said insulating member
  • corona emitting means adjacent the second surface of said web at the area of contact between said first surface ond said insulating member, said corona emitting means comprising at least one electrode to which is supplied A.C. potential to cause alternately positive and negative corona emission and positive DC. potential to cause the quantities of positive and negative emission to be substantially equal;

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
US328984A 1963-12-09 1963-12-09 Xerographic developing apparatus with controlled corona means Expired - Lifetime US3332396A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US328984A US3332396A (en) 1963-12-09 1963-12-09 Xerographic developing apparatus with controlled corona means
GB4860364A GB1060679A (en) 1963-12-09 1964-11-30 Controlled xerographic development
DE1964R0039391 DE1288915B (de) 1963-12-09 1964-12-04 Verfahren und Vorrichtung zur wahlweisen Entwicklung von Strich- oder flaechigen Ladungsbildern
FR997869A FR1419973A (fr) 1963-12-09 1964-12-08 Procédé de développement xérographique contrôlé
BE656893A BE656893A (fr) 1963-12-09 1964-12-09

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US328984A US3332396A (en) 1963-12-09 1963-12-09 Xerographic developing apparatus with controlled corona means
US328934A US3171619A (en) 1962-12-11 1963-12-09 Aircraft undercarriages
FR997869A FR1419973A (fr) 1963-12-09 1964-12-08 Procédé de développement xérographique contrôlé

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FR (1) FR1419973A (fr)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3376852A (en) * 1966-12-27 1968-04-09 Xerox Corp Dielectric belt developing
US3470417A (en) * 1966-10-03 1969-09-30 Eastman Kodak Co Method of altering electrostatic charge on an insulating material
US3575505A (en) * 1968-07-30 1971-04-20 Eastman Kodak Co Automatic bias control
US3620617A (en) * 1969-11-24 1971-11-16 Ibm Electrophotographic apparatus with improved toner transfer
US3663219A (en) * 1967-05-23 1972-05-16 Canon Camera Co Electrophotographic process
US3708661A (en) * 1970-02-21 1973-01-02 Philips Corp Corona discharge for electro-static charging
US3739748A (en) * 1970-12-15 1973-06-19 Xerox Corp Donor for touchdown development
US3759222A (en) * 1971-03-04 1973-09-18 Xerox Corp Microfield donor with continuously reversing microfields
US3866574A (en) * 1973-02-15 1975-02-18 Xerox Corp Xerographic developing apparatus
US3870515A (en) * 1970-05-20 1975-03-11 Xerox Corp Method for electrostatic paper stripping by neutralization of transfer charge
US3918966A (en) * 1972-09-28 1975-11-11 Commw Of Australia Liquid development of an electrical image in which a pulsating field is employed
US3949703A (en) * 1971-12-30 1976-04-13 Savin Business Machines Corporation Self-cleaning developer applicator
US4154520A (en) * 1976-10-06 1979-05-15 Olympus Optical Co., Ltd. Electrostatic latent image developing device
US4195991A (en) * 1977-10-21 1980-04-01 James River Graphics Inc. Electrographic recording method of applying an electric field opposite the charge retaining layer
US4258116A (en) * 1977-12-22 1981-03-24 Canon Kabushiki Kaisha Process for developing electrostatic latent images
US4498756A (en) * 1981-04-07 1985-02-12 Tokyo Shibaura Denki Kabushiki Kaisha Developing device
US4614419A (en) * 1984-09-20 1986-09-30 Xerox Corporation Pre-development inductive charging of developer material

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2885556A (en) * 1955-08-01 1959-05-05 Haloid Xerox Inc Simultaneous charging device and method
US2895847A (en) * 1953-12-21 1959-07-21 Battelle Development Corp Electric image development
US2982647A (en) * 1956-06-14 1961-05-02 Haloid Xerox Inc Electrostatic image reproduction
US2996400A (en) * 1956-08-30 1961-08-15 Eastman Kodak Co Positive and negative electroprinting
US3011473A (en) * 1958-05-01 1961-12-05 Xerox Corp Xerographic apparatus
US3152012A (en) * 1960-12-19 1964-10-06 Ibm Apparatus for the development of electrostatic images
US3203394A (en) * 1962-10-01 1965-08-31 Xerox Corp Xerographic development apparatus
US3216844A (en) * 1962-03-02 1965-11-09 Xerox Corp Method of developing electrostatic image with photoconductive donor member
US3244083A (en) * 1962-10-23 1966-04-05 Xerox Corp Xerographic device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2895847A (en) * 1953-12-21 1959-07-21 Battelle Development Corp Electric image development
US2885556A (en) * 1955-08-01 1959-05-05 Haloid Xerox Inc Simultaneous charging device and method
US2982647A (en) * 1956-06-14 1961-05-02 Haloid Xerox Inc Electrostatic image reproduction
US2996400A (en) * 1956-08-30 1961-08-15 Eastman Kodak Co Positive and negative electroprinting
US3011473A (en) * 1958-05-01 1961-12-05 Xerox Corp Xerographic apparatus
US3152012A (en) * 1960-12-19 1964-10-06 Ibm Apparatus for the development of electrostatic images
US3216844A (en) * 1962-03-02 1965-11-09 Xerox Corp Method of developing electrostatic image with photoconductive donor member
US3203394A (en) * 1962-10-01 1965-08-31 Xerox Corp Xerographic development apparatus
US3244083A (en) * 1962-10-23 1966-04-05 Xerox Corp Xerographic device

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3470417A (en) * 1966-10-03 1969-09-30 Eastman Kodak Co Method of altering electrostatic charge on an insulating material
US3376852A (en) * 1966-12-27 1968-04-09 Xerox Corp Dielectric belt developing
US3663219A (en) * 1967-05-23 1972-05-16 Canon Camera Co Electrophotographic process
US3575505A (en) * 1968-07-30 1971-04-20 Eastman Kodak Co Automatic bias control
US3620617A (en) * 1969-11-24 1971-11-16 Ibm Electrophotographic apparatus with improved toner transfer
US3708661A (en) * 1970-02-21 1973-01-02 Philips Corp Corona discharge for electro-static charging
US3870515A (en) * 1970-05-20 1975-03-11 Xerox Corp Method for electrostatic paper stripping by neutralization of transfer charge
US3739748A (en) * 1970-12-15 1973-06-19 Xerox Corp Donor for touchdown development
US3759222A (en) * 1971-03-04 1973-09-18 Xerox Corp Microfield donor with continuously reversing microfields
US3949703A (en) * 1971-12-30 1976-04-13 Savin Business Machines Corporation Self-cleaning developer applicator
US3918966A (en) * 1972-09-28 1975-11-11 Commw Of Australia Liquid development of an electrical image in which a pulsating field is employed
US3866574A (en) * 1973-02-15 1975-02-18 Xerox Corp Xerographic developing apparatus
US4154520A (en) * 1976-10-06 1979-05-15 Olympus Optical Co., Ltd. Electrostatic latent image developing device
US4195991A (en) * 1977-10-21 1980-04-01 James River Graphics Inc. Electrographic recording method of applying an electric field opposite the charge retaining layer
US4258116A (en) * 1977-12-22 1981-03-24 Canon Kabushiki Kaisha Process for developing electrostatic latent images
US4498756A (en) * 1981-04-07 1985-02-12 Tokyo Shibaura Denki Kabushiki Kaisha Developing device
US4521098A (en) * 1981-04-07 1985-06-04 Tokyo Shibaura Denki Kabushiki Kaisha Developing device
US4614419A (en) * 1984-09-20 1986-09-30 Xerox Corporation Pre-development inductive charging of developer material

Also Published As

Publication number Publication date
FR1419973A (fr) 1965-12-03

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