US3005389A - Electrophotographic copying device - Google Patents

Electrophotographic copying device Download PDF

Info

Publication number
US3005389A
US3005389A US727018A US72701858A US3005389A US 3005389 A US3005389 A US 3005389A US 727018 A US727018 A US 727018A US 72701858 A US72701858 A US 72701858A US 3005389 A US3005389 A US 3005389A
Authority
US
United States
Prior art keywords
sheet
transparency
master copy
xerographic
powder
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
US727018A
Other languages
English (en)
Inventor
Limberger Walter
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.)
Individual
Original Assignee
Individual
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
Priority to DEL24536A priority Critical patent/DE1130698B/de
Priority claimed from DEL29506A external-priority patent/DE1101148B/de
Priority to GB9491/57A priority patent/GB819510A/en
Priority to CH353384D priority patent/CH353384A/de
Priority to US648671A priority patent/US3005388A/en
Priority claimed from US648671A external-priority patent/US3005388A/en
Priority to FR1173405D priority patent/FR1173405A/fr
Application filed by Individual filed Critical Individual
Priority to US727018A priority patent/US3005389A/en
Publication of US3005389A publication Critical patent/US3005389A/en
Application granted granted Critical
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
    • G03G15/22—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
    • 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
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat

Definitions

  • the present invention relates to a device for the reproduction of a master copy on a flexible carrier having an electrostatically charged photoconductive layer.
  • the invention has for its principal object the provision of means for solving this problem in a more satisfactory manner than has heretofore been proposed.
  • the invention provides a device for the production of xerographic copies on sheet material in which a housing is subdivided into an upper and lower chamber by a partition forming, within the lower chamber, a preferably horizontal guide channel for the sheets carrying the charged layer which, together with the master copy, are inserted .between a pair of synchronously driven feed rollers through slots in the housing wall.
  • the two feed rollers are respectively positioned adjacent a first transparency, mounted inside the upper chamber next to a suitable lightsource, and a second transparency, included in the partition to form a light-transmitting portion therein.
  • the master copy is caused to pass below the first transparency while the xerographic sheet advances underneath the second transparency through the guide channels Walls in the upper chamber divide it into an illumination compartment and a developing compartment, separated from each other, andalso define a passage in the shape of a flattened tube above the second transparency through whigh light reflected from the master'copy is directed by an appropriate optical system, such as an objective and a mirror, onto the xerographic copying layer whose speed of movement is related to the speed of movement of the master copy in accordance with the desired scale of reproduction.
  • an appropriate optical system such as an objective and a mirror
  • the developing compartment con' tains, above an opening in the partition, a powder-distributing device for making the latent image visible, followed by a fusing device within the guide channel for fixing the distributed powder to the Xerographic layer.
  • an electrode assembly is also provided in the device for charging the xerographic layer ahead of the transparency associated with the guide channel.
  • the two transparencies are inclined at a small angle-with respect to the horizontal,
  • FIG. 1 shows a sectional elevation through a device for producing copies on xerographic sheets in accordance with the invention
  • FIG. 2 is an enlarged top plan view of a detail of the device according to FIG. 1
  • the illustrated parts of the apparatus e.g. rollers, cylinders, intermediate walls and the like, are supported on one or both of the side walls of the device.
  • the housing of the device shown in the drawing consists of a lower, box-shaped chamber Inf and an upper, generally pyramidal chamber 102a, 102b.
  • Chamber 101 is formed by a base 1 and upstanding end walls 2 and 3 perpendicular thereto.
  • feet 4, 5 are provided which consist of elastic material, for example rubber, designed to prevent the transfer ofvibrations to the device.
  • wall parts 6, 7 run together. upwardly to form the upper chamber. Louvers 8, 9 are provided in the inclined wall parts 6, 7 to facilitate the escape of the heat produced by the illuminating device and the fusion device respectively disposed within the compartments 102a, 1021) of that chamber as more fully disclosed hereinafter.
  • inlet slots 10, 11 are provided for the master copy and the xerographic sheet.
  • the guide paths extending from these'slots lead on the one hand to a first plate 12 for the master copy and on the other hand to a second plate or window 13 for the xerographic sheet.
  • These plates preferably consist of a transparency, i.e.' a' glass plate which passes ultraviolet or yellow light according to the kind or spectral sensitivity of the paper used, and an opaque supporting frame which is imbedded in the glass and defines a light-transmissive window aperture therein. It will be noted that the two plates 12, 13 are mounted in close proximity to each other.
  • Pressure rollers 1d, -15 serving as feeding means, are arranged beneath the plates 12 and 13, respectively. These rollers, shown interconnected for synchronized rotation, preferably have an elastic surface. If required, they may be resiliently supported by means of springs with freedom of movement in the directions of the re spective platforms.
  • the roller 15 is so arranged in the housing in the vicinity of the end wall 2 that the master copy, after passage under the plate 12, is fed directly into an outlet slot to where it is discharged from the device.
  • lamps 17, 18 are provided which illuminate the central section of the plate. are located beyond the lamps.
  • the division between the lower and upper housing chambers is effected by a partition, formed by shields 103 and 28, which seals the lower chamber 101 against the illuminating compartment 102a but is open toward the developing compartment 102b at 104, 105.
  • this partition in the guide path for the xerographic sheet between the inlet slot 11 and the plate 13, an electrode assembly 21, 22 is disposed between which the sheet passes.
  • the electrode as- Reflectors 19, 20-
  • Underneath sembly consists of rollers 21, 22 which are manufactured of electrically conductive material and at the same time serve as part of the feeding mechanism for the sheet.
  • the distance between the rollers 21, 22 is about the same as the thickness of the sheet.
  • the potentials for charging the xerographic layer are applied to these rotary electrodes.
  • the positive electrode is located above the path for the xerographic layer.
  • the pressure roller M conveys the xerographic sheet after its exposure to a channel defined by the partition member 28 and a vibratory guide member 23.
  • This latter member is swingable about a pivot 24 and is oscillated by a reciprocating rocker arm 49, driven from a motor 1% by an eccentric shaft 25, to remove any loosely adhering developing powder not held by electrostatic attraction.
  • a reciprocating rocker arm 49 driven from a motor 1% by an eccentric shaft 25, to remove any loosely adhering developing powder not held by electrostatic attraction.
  • the guide member 23 is perforated so that powder passing beneath the xerographic sheet falls onto a chute 33. Particularly in the lowest part of the member 23, outlet openings 26 of large cross-section are provided for the powder so that the excess, through the forces of gravity and vibration, is caused to fall into a container 27 via the chute 33.
  • the partition member 28 is bent upwardly at opening 104 to form a funnel 253 aligned with the outlet of the powderdi'stributing device thereabove.
  • the powder-distributing device consists essentially of a hopper 32 which is accessible from outside by way of a removable lid 30 and a connecting channel 31.
  • the powder collected in the container 27 can be returned through this channel for re-use in the hopper 32.
  • the base of the hopper 32 runs funnel-shaped to an outlet opening 36. in which a dispensing roller 34 rotates.
  • the roller 34 closes the outlet opening 36 on one side and, preferabl by means of depressions in its suitably profiled surface, transports the powder on rotating to the lower elastic lip 35 of the hopper opening 36.
  • the xerographic sheet After leaving the channel above vibratory member 23, the xerographic sheet passes to a rotating cylinder 37 of a fusion device which, in combination with pressure rollers 38, 39, 40. serves at the same time for the further advance of the sheet over the fusion device to the outlet slot 41.
  • motor 1% drives the cylinder 37 as well as the rollers 34, 14 and 25.
  • a heating device 52 is arranged in the cylinder 37, its rising convection heat passing directly to the region of the cylinder which communicates with the Xerographic sheet while radiated heat from this source is collected by the cylinder and conveyed by its rotation to the sheet.
  • the device consisting of the rollers 38, 39, 40 and the cylinder 37 with its heating device 52 is arranged to be vertically adjustable with respect to the guide member 23, within partition opening 185, as indicated by the arrow 51 whereby the angle of contact between the sheet and the cylinder 37 can be increased or decreased.
  • This arrangement affords an extremely advantageous, instantaneously effective heating control to satisfy the existing requirements, thus supplementing the control facilities afforded by the adjustability of the swing of the vibratory guide member 23 and, if desired, by the variability of the number of revolutions of the dispensing roller 34.
  • FIG. 2 a top plan view of the fusing device 31- is shown.
  • the xerographic sheet is indicated in this figure at 59.
  • Under the sheet is located the cylinder 37, whereas at each edge of the sheet there is disposed a respective set of pressure rollers 38, 39, 40.
  • the rollers 38, 39, 46 are preferably mounted with freedom of radial motion relative to the cylinder 37 and are pressed by springs 197 against the periphery of the latter, as illustrated schematically in FIG. 1.
  • the upper chamber of the housing is divided into its compartments M261, lilZb by a double wall 42, 43 rising perpendicularly from the plate 13 to .form a ,flattened tube for the passage .of light rays reflected by a mirror 44 at the upper end of the housing, the path of these rays being generally transverse to the surface of the sheet 5% ⁇ by reason of the small relative inclination of plates 12 and 13.
  • the objective 45 can be made readily accessible by a cover so that, eg in connection with an adjustment of the mirror 44, alterations can be carried out in the image scale.
  • the part of the apparatus containing the mirror 44 representing a portion of the illuminating compartment W241, is tightly sealed by a wall 46 as well as by the wall 42 with respect to the developing compartment 102']; in which the powder-distributing device 32 is located.
  • the illuminating or exposure device 17-20 and the fusing device 31-40 are partially covered by sections of the wall parts 6, 7 provided with the louvers 8, 9, so that the generated currents of hot air can escape directly into the atmosphere. Additionally, shields 47, 48 are provided which lead the rising air currents to these louvers 8, 9, so that the inside of the apparatus is protected against the heat developed by the illuminating and fusing devices.
  • the master copy and the .xerographic sheet are inserted into the slots 10, 11 so that the image of the master copy and the photoconductive layer face each other.
  • Motor 106 may be triggered by a suitable switch in one of the inlet slots, such as a contact 108 arranged in slot It) in the path of the master copy, to drive the movable elements of the apparatus.
  • a suitable switch in one of the inlet slots such as a contact 108 arranged in slot It) in the path of the master copy, to drive the movable elements of the apparatus.
  • the master copy passes underneath the transparency 12, its image side is illuminated by the lamps 17, 18 and the reflected light rays pass by way of the optical system 44, 45, the light tube formed by wall members 42 and 43 and the transparency 13 to the xerographic layer carried by the sheet 50 which had previously been charged on its passage between the electrodes 21, 22.
  • developing powder from hopper 32 is distributed onto the illuminated layer, the overflow being shaken loose by the vibrator 49 as the sheet ascends the sloping part of guide member 23.
  • the remaining particles, whose distribution corresponds to the latent image formed on the xerographic layer during the exposure step, are then fixed to the layer in the fusion device 37-40 to provide a permanent replica of the master copy.
  • An electrophotographic copying device for the reproduction of a master copy on a flexible carrier having an electrically chargeable photoconductive surface, comprising a housing, a first frame, a first transparency in said first frame, first feed means for advancing below said first transparency the master copy to be reproduced, a second frame positioned close to said first frame and inclined at a small angle relatively thereto, a second transparency in said second frame, second feed means for advancing said carrier below said second transparency, partition means including said second frame in said housing defining a generally horizontal channel .for the passage of the carrier with its photoconductive surface facing upward, walls rising substantially vertically from said second frame within said housing and forming an elongated flattened light tube terminating at said second transparency, optical focusing means of large focal length in said housing for directing light rays from said master copy through said first transparency, said light tube and said second transparency onto the upper surface of said carrier, said focusing means including a reflector aligned with said light tube at a location remote from said second transparency, the entire path of said light rays being
  • a device according to claim 1 wherein said frames are inclined at small angles with respect to the horizontal.
  • a device according to claim 1 wherein said housing has a side wall provided with an entrance slot for said master copy, an exit slot for said master copy and an admission slot for said carrier, said first feed means including a roller positioned between said entrance and exit slots.
  • a device according to claim 1 wherein said housing is provided with upwardly sloping side walls converging at a location above the upper end of said light passage.
  • said optical means comprises a light source positioned underneath one of said sloping walls, said heating means being positioned underneath the other of said sloping walls, said sloping walls being provided with louvers and with respective guide panels for directing hot air from said light source and from said heating means into the atmosphere by way of said louvers, respectively.
  • An electrophotographic device for the reproduction of a master copy on a flexible carrier having an electrically charged photoconductive surface, comprising a housing, partition means dividing said housing into a first and a second chamber, said partition being being provided with a window, walls in said first chamber extending substantially perpendicularly from said partition means on opposite sides of said window and forming an elongated flattened light tube terminating at said Window, means including said walls in said first chamber dividing the latter into two mutually isolated compartments, a transparent plate in one of said compartments near said partition means and said walls, a first driven roller positioned in one of said compartments close to said plate for advancing the master copy to be reproduced past said plate, a second driven roller coupled with said first roller and positioned in said second chamber close to said window for advancing the flexible carrier past said window, means including said partition means forming between said rollers a first guide path for said master copy and a second guide path for said carrier, guide means in said second chamber extending adjacent said partition means and forming therewith an extension of said second guide
  • said hopper means comprises afunnel and a powder-dispensing roller synchronized with said rollers adjacent the mouth of said funnel.
  • a device wherein said funnel is provided at its mouth with a depending lip elastically engaging the periphery of said roller.
  • a device further comprising vibratory means positioned in said channel beyond said hopper means for rocking said carrier and removing loosely adhering powder therefrom.
  • said partition means extends generally horizontally and includes a sloping movable wall portion, said vibratory means comprising a rocker mechanism connected with said movable wall portion to impart oscillatory motion thereto.
  • heating means comprises a rotatable heated roller positioned to support said carrier from below and co-operating roller means positioned to hear from above upon the photoconductive carrier surface.
  • a device comprising mounting means for said heated roller and for said co-operating roller means enabling vertical adjustment thereof.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Elimination Of Static Electricity (AREA)
US727018A 1956-03-28 1958-03-24 Electrophotographic copying device Expired - Lifetime US3005389A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
DEL24536A DE1130698B (de) 1956-03-28 1956-03-28 Vorrichtung zum Herstellen von Kopien mit einem eine fotoleitende Schicht aufweisenden Schichttraegerband
GB9491/57A GB819510A (en) 1956-03-28 1957-03-22 Improvements in or relating to the production of copies
CH353384D CH353384A (de) 1956-03-28 1957-03-26 Vorrichtung zum Herstellen von Kopien
US648671A US3005388A (en) 1956-03-28 1957-03-26 Electrophotographic copying device
FR1173405D FR1173405A (fr) 1956-03-28 1957-03-28 Appareil à confectionner des copies
US727018A US3005389A (en) 1956-03-28 1958-03-24 Electrophotographic copying device

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DEL29506A DE1101148B (de) 1956-03-28 1956-03-28 Einbrennvorrichtung zur Fixierung eines Pulverbildes auf einer fotoleitenden Schicht
DE353384X 1956-03-28
DEL24536A DE1130698B (de) 1956-03-28 1956-03-28 Vorrichtung zum Herstellen von Kopien mit einem eine fotoleitende Schicht aufweisenden Schichttraegerband
US648671A US3005388A (en) 1956-03-28 1957-03-26 Electrophotographic copying device
US727018A US3005389A (en) 1956-03-28 1958-03-24 Electrophotographic copying device

Publications (1)

Publication Number Publication Date
US3005389A true US3005389A (en) 1961-10-24

Family

ID=32398294

Family Applications (1)

Application Number Title Priority Date Filing Date
US727018A Expired - Lifetime US3005389A (en) 1956-03-28 1958-03-24 Electrophotographic copying device

Country Status (5)

Country Link
US (1) US3005389A (fr)
CH (1) CH353384A (fr)
DE (1) DE1130698B (fr)
FR (1) FR1173405A (fr)
GB (1) GB819510A (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3088386A (en) * 1959-11-16 1963-05-07 American Photocopy Equip Co Electrophotographic photocopy machine
US3146688A (en) * 1961-05-01 1964-09-01 Xerox Corp Xerographic machine
US3168022A (en) * 1956-03-08 1965-02-02 Zindler Lumoprint Kg Apparatus for producing photocopies
US3180239A (en) * 1962-04-24 1965-04-27 Plastic Coating Corp Apparatus for the photoelectrostatic reproduction of images
US3207050A (en) * 1961-07-25 1965-09-21 Zindler Lumoprint Kg Apparatus for the production of copies
US3221597A (en) * 1963-10-09 1965-12-07 Clifford C Vogt Roll tape copy machine
US3221621A (en) * 1961-07-26 1965-12-07 Zindler Lumoprint Kg Devices for the production of copies
US3272100A (en) * 1963-10-30 1966-09-13 Nuclear Corp Of America Electrostatic copier
US3345926A (en) * 1964-11-12 1967-10-10 Formfoto Mfg Company Electrophotographic copying machine
US3441345A (en) * 1963-05-20 1969-04-29 Addressograph Multigraph Photocopying
US3446184A (en) * 1964-10-26 1969-05-27 Minnesota Mining & Mfg Apparatus for powder development of liquid latent images
US3490843A (en) * 1964-06-30 1970-01-20 Savin Business Machines Corp Electrostatic copier

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1216108B (de) * 1962-11-30 1966-05-05 Harris Intertype Corp Elektrofotografisches Geraet
EP0077553B1 (fr) * 1981-10-20 1985-09-04 E.I. Du Pont De Nemours And Company Récupération de toner à excès pour un appareil de développement automatique

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1153685A (en) * 1911-05-12 1915-09-14 Joseph Guerzoni Projection apparatus.
US1255963A (en) * 1917-08-14 1918-02-12 M Adelbert Washburn Seprating-machine.
US2221776A (en) * 1938-09-08 1940-11-19 Chester F Carlson Electron photography
US2234717A (en) * 1939-03-22 1941-03-11 Eastman Kodak Co Photo copying machine
US2624652A (en) * 1944-10-11 1953-01-06 Chester F Carlson Graphic recording
US2716048A (en) * 1952-08-14 1955-08-23 Charles J Young Electrostatic facsimile receiver
US2748018A (en) * 1953-06-05 1956-05-29 Ransburg Electro Coating Corp Apparatus and method of electrostatic powdering
US2791949A (en) * 1956-02-01 1957-05-14 Haloid Co Xerographic copying device
US2885955A (en) * 1955-05-11 1959-05-12 Haloid Xerox Inc Xerographic machine

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1153685A (en) * 1911-05-12 1915-09-14 Joseph Guerzoni Projection apparatus.
US1255963A (en) * 1917-08-14 1918-02-12 M Adelbert Washburn Seprating-machine.
US2221776A (en) * 1938-09-08 1940-11-19 Chester F Carlson Electron photography
US2234717A (en) * 1939-03-22 1941-03-11 Eastman Kodak Co Photo copying machine
US2624652A (en) * 1944-10-11 1953-01-06 Chester F Carlson Graphic recording
US2716048A (en) * 1952-08-14 1955-08-23 Charles J Young Electrostatic facsimile receiver
US2748018A (en) * 1953-06-05 1956-05-29 Ransburg Electro Coating Corp Apparatus and method of electrostatic powdering
US2885955A (en) * 1955-05-11 1959-05-12 Haloid Xerox Inc Xerographic machine
US2791949A (en) * 1956-02-01 1957-05-14 Haloid Co Xerographic copying device

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3168022A (en) * 1956-03-08 1965-02-02 Zindler Lumoprint Kg Apparatus for producing photocopies
US3088386A (en) * 1959-11-16 1963-05-07 American Photocopy Equip Co Electrophotographic photocopy machine
US3146688A (en) * 1961-05-01 1964-09-01 Xerox Corp Xerographic machine
US3207050A (en) * 1961-07-25 1965-09-21 Zindler Lumoprint Kg Apparatus for the production of copies
US3221621A (en) * 1961-07-26 1965-12-07 Zindler Lumoprint Kg Devices for the production of copies
US3180239A (en) * 1962-04-24 1965-04-27 Plastic Coating Corp Apparatus for the photoelectrostatic reproduction of images
US3441345A (en) * 1963-05-20 1969-04-29 Addressograph Multigraph Photocopying
US3221597A (en) * 1963-10-09 1965-12-07 Clifford C Vogt Roll tape copy machine
US3272100A (en) * 1963-10-30 1966-09-13 Nuclear Corp Of America Electrostatic copier
US3490843A (en) * 1964-06-30 1970-01-20 Savin Business Machines Corp Electrostatic copier
US3446184A (en) * 1964-10-26 1969-05-27 Minnesota Mining & Mfg Apparatus for powder development of liquid latent images
US3345926A (en) * 1964-11-12 1967-10-10 Formfoto Mfg Company Electrophotographic copying machine

Also Published As

Publication number Publication date
FR1173405A (fr) 1959-02-25
GB819510A (en) 1959-09-02
DE1130698B (de) 1962-05-30
CH353384A (de) 1961-04-15

Similar Documents

Publication Publication Date Title
US3005389A (en) Electrophotographic copying device
US3088386A (en) Electrophotographic photocopy machine
US3382360A (en) Xerographic charging system having means for providing an air cushion between the charging device and the xerographic drum
US3062094A (en) Electrophotographic copying apparatus
PL80003B1 (fr)
US3542468A (en) Microfilm enlarger-copier
US4063810A (en) Color transparency reproducing machine
US3348523A (en) Automatic toner control system
US3901593A (en) Copying machines of the variable magnifying power type
GB2041830A (en) Modular electrophotographic copying machine
IL30229A (en) Contact heat fusing device
US3168022A (en) Apparatus for producing photocopies
US3784300A (en) Pre-transfer station
US3424131A (en) Electroded cascade development system
US3005388A (en) Electrophotographic copying device
US3526338A (en) Method and controller for dispensing electroscopic material
US3278972A (en) Xerographic plate cleaning apparatus
US3527387A (en) Developer replenishing programming system
US3348521A (en) Automatic toner control system
US2961932A (en) Electrophotographic copying apparatus
US3397627A (en) Photoelectrostatic copying machine
US3411932A (en) Quality xerographic reproductions
US2950661A (en) Preparation of copies by xerography
US3303817A (en) Xerographic developing apparatus
US3067720A (en) Xerographic developing apparatus