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Publication numberUS2831409 A
Publication typeGrant
Publication dateApr 22, 1958
Filing dateJul 18, 1955
Priority dateJul 18, 1955
Publication numberUS 2831409 A, US 2831409A, US-A-2831409, US2831409 A, US2831409A
InventorsBixby William E, Kriss Robert S
Original AssigneeHaloid Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Xerographic camera
US 2831409 A
Images(1)
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Description  (OCR text may contain errors)

April 1953 w. E. BIXBY ET x. 2,831,409

XEROGRAPHIC CAMERA Filed July 18, 1955 EXHAUST PRESSURE SOURCE Fly. 2

United States vvXEROGRAPHIC CAMERA William E. Bixby and Robert S. Kriss, Columbus, Ohio,

assiguors, by mesne assignments, to The Helmet Company, Rochester, N. Y. a corporation of New York Application July 18, 1955, Serial No. 522,540

6 Claims. (31. 9s-- 1.7

This invention relates to .the field of xerography and particularly to an improved xerographic camera apparatus for the rapid processing of xerographic plates.

.A process of electrophotography or Xerography is described and claimed in Carlson Patent 2,297,691, issued October 6, i942, and certain forms of xerographic apparatus for use in such a process are disclosed in Carlson Patent 2,357,809, issued September 12, 1944. Basically, the process of Xerography utilizes a Xerographic plate which in one form may consist of a metal plate or foil coated with a photoconductive insulating material such as sulphur, anthracene, an insulating form of selenium, or the like. This coating is given a uniform electrostatic charge onits surface, as by frictional rubbing with a cloth or brush, after which the plate may be exposed to a light image. The light discharges the coating in the areas which are struck by the light. The remaining electrostatic latent image may then be developed with a finely divided material, such as a powder or a liquid mist, to form a visible image. This visible image may then be transferred to paper or other suitable surface and the plate may be cleaned and used again;

During the development of the art of Xerography, many advances and improvements have been made in the various materials and methods that constitute the process to the point that Xerographic systems are currently in wide commercial use for the production of line copy and continuous tone copy, and adaptations of such systems for the production of photographs by xerographic methods are in a highly advanced stage of experimental use. The most significant advances that have permitted the wide application of this art are improvements in the methods and apparatus required for charging and for developing the xerographic plates, as Well as improvements of the photographic response of the xerographic plates themselves, whereby xerographs may now be made at'speeds and under conditions approaching these common in conventional silver photography.

For example, one advance which has been made in charging devices comprises the substitution of a corona charging device, i. e., a filament connected to a high voltage source, for the frictional charging means. Arrangements employing such a device are disclosed in Carlson Patent 2,551,582, issued May 8, i951, in Carlson Patent 2,588,699, granted March 1952, and in copending application Serial No. 319,472, filed by C. R.

Mayo et at. on November 3, 1952. This arrangement permits the charging of a plate to a higher potential than can be obtained frictionally and the plate potential can bepredetermined approximately, by regulating the charging voltage. and controlling the speed at which the plate is passed under the charging source. Such an arrangement requires the regulation of the high voltage source and of the speed of the plate if close control of the plate voltage, is. to be obtained so that it is ideally suited for stationary equipment. in which power supply requirements can readily be fulfilled.

A further innovation in plate charging apparatus is disclosed in Carlson Patent 2,701,764, issued February 8,

1955, wherein a radioactive source is provided to generate 7 ions in front of a plate to be charged and an electrical eld is imposed to carry the ionic charges to the surface of the plate. in an embodiment of that invention a radioactive source is supported in front of the plate and a potential source is connected to apply an electric field between the source and the plate. By this arrangement the plate may be held stationary during the charging cycle. With a device of this sort it is only necessary for the operator to place the plate and the charging unit in juxtaposition for a period of a few or more seconds, depending upon the size of the plate and the arrangement and type of radioactive material, in order to place a uniform electrostatic charge over the entire surface of the plate and condition it for use in making an exposure to a light image or other source of radiation to be recorded.

A further significant advance that has facilitated the production of xerographic copy has been in the improvement of powder development mechanisms, for example, such as that disclosed in application Serial No. 353,520. filed in the name of Eugene C. Ricker on May 7, 1953. In a device of this sort a high pressure stream of gas is directed against a powder or carbon impregnated belt or ribbon and the powder particles are blown through a capillary tube whereby they are electostatically charged,

and are then blown through a chamber formed by the xerographic plate and a development electrode wherein the charged powder is attracted to the electrostatic latent image on the plate and forms a powder image corresponding thereto. Using a device of this sort it isnow possible to'develop a completeimage in a period of from one to three seconds.

A variety of improvements have also been made in the selection of materials and methods of fabrication of Xerographic plates whereby the photographic sensitivity and the spectral response of these plates has been substantially improved; For example, the sulphur or anthracene faced plates disclosed in Carlson Patent 2,297,691 have, in general, been replaced for commercial applications by selenium-surfaced aluminumbacked plates. Plates of this short are of such characteristics that they are ideally suited for use in the production of line copy although they are somewhat limited from the standpoint of photographic sensitivity and spectral response. Plates of this type are particularly useful for general commercial use because they may readily be charged to a uniform potential by any of a variety of types of charging devices and, when so charged, retain the charge for appreciable periods of time when protected from exposure to light prior to the actual working exposure.

The improvements in the field of Xerographic plate development have led to a number of methods for producing highly sensitive, panchromatic Xerographic plates capable of yielding good quality pictures. In general, these plates comprise a layer of vitreous and/or noncrystailine selenium in combination with one or more materials spread on a metallic backing. Such plates have been found to have better than ten to fifteen times the photographic speed of commercial selenium plates and are essentially panchromatic in their response to light. However, it is noted that as photographic speed and panchromaticity are increased, the dark-decay rate of such plates also increases, 1'. e., even through plates such as these are charged and handled under darkroom conditions the electrostatic charge placed thereon tends to decay in a very short period when compared with conventional selenium plates. For example, in some instances it was found that in periods of from three to fifteen seconds after charging the plates had lot sufiicient of their electrostatic charge to make them unusuable for recording a xerographic image. Such high dark-decay rates makes plates of this type impractical for use with usual darkroom procedure, inasmuch as too much time is required in handling the plate between the end of the char ing operation and the end of the development operation.

In usual darkroom procedure the plate is charged by passing it under a corona discharge and placing it in a plate holder. The plate is then carried to and placed in a camera, exposed, and returned to the darkroom where it is removed from the plate holder. It is then placed on the development unit and the electrostatic image on the plate is developed. The shortest time in which this proceduce can be carried out in any parctical commercial method is about one minute. However, in appreciably less than one minute the potential on certain high sensitivity xerographic plates tends to drop too far, even in darkness, for the plate to be usable in making a picture.

In order to use such plates, the present invention discloses a rapid processing xerographic camera, whereby the plates can be manipulated extremely rapidly in the interval between charging and development. In a preferred embodiment of the invention the camera comprises a hinge-type construction wherein the camera back opens to permit placing the plate on a holder. When the back is closed the holder is positioned so that the plate is in the image plane of the camera lens. The plate is then charged by means of a radioactive charging unit that is swung from the top of the camera to a position directly in front of the plate. In this position, electrical contact is made and voltage is applied between the plate and the charging unit during the charging cycle. When charging is complete the charging unit is restored to its original position and the plate is exposed to the subject to be reproduced through a conventional lens mount ed at the forward end of the camera. Immediately after exposure, the hinged plate holder is swung into operative relationship with the electrode of a powder cloud development unit. A charged carbon powder is then blown into the development chamber formed by the plate and the development electrode whereby the electrostatic latent image remaining on the plate is coated with charcoal particles. When development is complete the plate may be removed from the camera to transfer the charcoal particle image by an conventional means, since the charged charcoal particles when one in contact with the plate remain affixed thereto by electrostatic attraction even though the original charge placed on the plate may decay entirely. By means of the arrangement thus proposed, the entire operation of exposure and development can be completed in a period of from two to three seconds after the charging of the plate is completed.

The principal object of the present invention is to improve the construction of xerographic cameras for use with high speed xerographic plates. A further object is to provide improved apparatus for the rapid processing of xerographic plates. A further object is to provide a compact and convenient apparatus for charging, exposing, and developing high speed xerographic plates. Other objects of the invention will be apaprent from the following description.

A preferred form of the invention is shown in the appended drawings in which:

Fig. l is a cutaway isometric view of the xerographic camera of the invention;

Fig. 2 is a functional schematic side elevation of the xerographic camera of the invention in conjunction with a conventional powder cloud developing unit.

Fig. 3 is a schematic side elevation of the charging unit of the camera in operated position to charge a plate; and

Fig. 4 is a schematic sectional view of the development electrode, showing a xerographic plate in operative relationship therewith.

In the arrangement shown in Figs. 1 and 2 the rapidprocess xerographic camera of the invention includes a light-tight, box-like structure having side walls 1 and 2,

4 top and bottom walls 3 and 4, respectively, and a front wall 5 in which is mounted any suitable and conventional lens and shutter element 6. The rear wall 7 of the camera is conveniently hinged on bottom wall 4 to provide ready access to the interior of the camera and may be latched in closed position by any convenient means. Journaled in suitable bearings 8 in side walls 1 and 2 is a transverse shaft 9 that is mounted in a manner to have its axis of rotation parallel to the plane of the focal plane of lens element 6. Fixed on shaft 9 are a pair of vertically extending angle members 10 having rearwardly extending bars 11 that serve to support a plate holder 12 that is provided with suitable internal grooves on its side and bottom rails to support a xerographic plate 15 which includes a suitable metallic backing plate 14 having a photoconductive surface layer 13. An upper rail 16 is provided to retain plate 15 in position in frame 12. The rearward ends of bars 11 abut the inner face of rear wall 7 when it is latched in closed position and serve to position plate holder 12 so that xerographic plate 15 is held in the focal plane of lens element 6. A suitable detent device (not shown) may be provided to retain shaft 9 so that plate holder 12 is maintained in a vertical position despite any movement of the camera. A vertically extending handle 17 is fixed to the outwardly extending end of shaft 9 whereby the shaft may be positioned as indicated in the drawings for charging and exposing operations, or may be rotated counter-clockwise to facilitate the insertion andremoval of a plate, or may be rotated in a clockwise direction through an angle of approximately 90 for developing operations, as described below. Preferably, plate holder 12 is formed of a suitable insulating material to permit the application of a biasing voltage during the developing cycle, if desired.

In order to place a uniform electrostatic charge on xerographic plate 15 the camera of the invention may include a radioactive charging unit 20 which, for convenience, may be of the type disclosed in Figs. 2 to 4, inclusive, of the above-mentioned Carlson Patent 2,701,764. In a device of this type of radioactive source is provided to generate ions in front of a plate to be charged and an electrical field is imposed to carry the ionic charges to the surface of the plate. In the present unit this device comprises an insulating plate 21 having affixed to its underside a pair of narrow metal strips 22 which are electroplated with a layer of polonium 28, which in turn may be electroplated with a very thin coating of gold which serves to protect the polonium but is sufiiciently thin to permit radioactive emission of alpha particles from the polonium into the air. Plate 21 is supported by a pair of bar members 23 which in turn are fixed to a transverse shaft 24 that is journaled in bearings 25, mounted in side walls 1 and 2, for rotation about an axis that is parallel to the plane of the focal plane of lens element 6.

When the charging unit is inactive, plate 21 is held in a substantially horizontal position by a suitable resilient detent 26 that is secured to top wall 3 of the camera. When the charging unit is to be rendered operative for charging purposes, shaft 24 is rotated clockwise by a handle 27 until the underside of plate 21 abuts the forwardly facing portions of angle members 10. This movement places the polonium plate bars 22 in proper spaced relationship to xerographic plate 15 (see Fig. 3) and, simultaneously, closes suitable electrical contacts (not shown) whereby, as fully disclosed in Carlson Patent 2,701,764, a D. C. potential source is connected between bars 22 and base plate 14 of xerographic plate 15. The potential source has a voltage equal to or slightly greater than the potential desired on the charged xerographic plate. The operator maintains this relationship for the required time to elfect complete charging of photoconductive layer 13 on plate 15 and then returns the charging unit to its substantially horizontal position. Plate 15 is then ready for use in making an exposure to a light image or other source of radiation to be recorded.

The following is belived to he an explanation of the process which takes place during the charging operation just described: Alpha particles emitted by the polonium layer into the air produce both positive and negative gas ions (and electrons) in the space between bars 22 and backing plate 14 of xerographic plate 15. If bars 22 are connected to the positive terminal of the battery, the field is such .as to drive positive ions toward the plate and negative ions and electrons in the direction of bars 22. While many of the ions and electrons probably recombine to form neutral molecules before reaching either surface, there are many positive ions which reach photoconductive coating 13 on xerographic plate 15 and deposit their charge on it. As a positive charge builds up on this photoconductive layer. the effective potential of its surface is raised, thereby reducing the electrical field between backing plate 14 and bars 22. Ions continue to deposit until a state of equilibrium is reached as the potential of the charged photoconductive layer on plate 15 becomes substantially equal to, or slightly less, than the potential of bars 22. in other words, the plate has then acquired a potential nearly equal to that of the D. C. source.

Although shown in conjunction with a radioactive charging unit it is apparent that the rapid process camera of the invention could readily have incorporated, as an alternate form of charging means, a stationary corona charging unit of the type shown in copending application Serial No. 495,945, filed in the name of James P. Ebert on March 2'2, i955.

After xerographic plate 15 is fully charged, charging unit 253 is restored to its inactive position (as in Figs. 1 and 2) and xerographic plate 15 is exposed to a subject in a conventional manner by means of lens and shutter element 6. The apparatus is so arranged that a minimum of time passes between the end of the charging cycle and the actual exposure so that the plate potential will not decay to an unusable extent. As soon as the exposure is complete, handle 17 is rocked clock-wiseto engage Xerographic plate 15' with the development mechanism so that the development cycle may be initiated immediately, as described below.

The development of the latent electrostatic image on the photoconductive layer of xerographic plate 15 is accomplished in a development mechanism that includes a development electrode 31 (see also Fig. 4) that is mounted in an insulating base member 32 which, in turn, is supported on bottom wall 4 of the camera. Electrode 31 is preferably of brass and is provided with milled slots at either end one of Which, slot 33, serves as an inlet slot to receive charged powder particles from a powder cloud generator, and the other, slot 35, serves as an exhaust slot through which excess powder particles and air are passed to an exhaust tube 3 6. Electrode 31 is surrounded by a resilient rubber gasket or O-ring 37 which, when xerographic plate 15 is moved downwardly, is engaged by the surface of plate 15 and thereby forms the side walls of a developing chamber, of which plate 15 forms the top and electrode 31 forms the bottom. Suitable shims 38 are mounted on electrode 31 and engage the outer edges of base plate 14 of the xerographic plate and serve to maintain the proper spacing between the photoconductive layer on plate 15 and the surface of electrode 31.

in order, to provide charged powder particles to develop the latent electrostatic image on plate 15, the apparatus includes a powder particle generator 40, of the type more fully disclosed in above-mentioned application Serial No. 353,520, that is connected to inlet slot 33 of the development electrode by a capillary tube 34. In this arrangement a suitable pressure source 43, such as a pressure pump or pressure reservoir which may, for example, be a container of pressurized gas, is arranged to feed air or gas into a tube 44 connected to powder cloud generator 40. Generator 40 comprises a suitable box or chamber 45 that is preferably sealed and relatively dust tight and contains a powder impregnated tape or ribbon 46 that is fed from a supply reel 47 to a take-up reel 48 which may be rotated by any suitable means such as a manually operated handle 49.

In operation, pressure supply 43 maintains the powder cloud chamber at a greater than ambient pressure. The output of generator 40 is controlled by a suitable valve 50 controlled by a lever 51 which is actuated by a operetc: when xerographic plate 15 is engaged with the developement assembly. When valve 50 is opened, a jet of pressurized air or gas is forced through nozzle 44 and blows a supply of powder particles from tape 46 into capillary tube 34. Inasmuch as tube 34 is a capillary, the powder particles in the air suspension will be in turbulent fiow and, through repeatedcontact with the walls of the tube, become charged triboelectrically to the proper polarity to be actuated to the latent electrostatic image on the surface of photoconductive layer 13.

These particles enter the development chamber formed by plate 15, development electrode 31 and gasket 37, and are attracted to the latent electrostatic image on the face of the plate. In usual operation, development of an entire electrostatic image is completed in a period of approximately one second by this type of apparatus.

In operation, the camera is loaded by releasing rear wall 7 and inserting a plate 15 in plate holder 12. To do this, shaft 17 is rocked counterclockwise to move shaft 9 from its vertical detent position so that plate 15 may more readily be inserted in plate holder 12. When the plate is inserted, handle 17 is returned to its vertical position and rear wall 7 is latched in closed position. The camera is then placed in a position in which the ultimate exposure is to be made. Immediately before such an exposure, charging unit 20 is rotated into juxtaposition with xerographic plate 15 and isheld there until the plate is fully charged. This charging operation may require from five seconds to one minute, depending upon the size of the plates involved and the size and relative strength of the radioactive units that are employed. When charging is complete, unit 20 is swung to its horizontal position by handle 27. and the exposure is made by means of lens and shutter element 6. immediately after exposure, handle 17 is rocked clockwise to press xerographic plate 15 into engagement with gasket 37 of the development mechanism whereby plate 15 is placed in proper relationship to development electrode 31. As soon as this proper relationship is attained, the operator initiates a flow of charged powder particles into the development chamber by means of lever 51 to elfect development of the electrostatic image.

With the type of equipment just described, the operations required from the end of the charging operation to the end of thedeveloping operation can be completed in from two to three seconds. Thus, regardless of the rate of dark-decay of the xerographic plate employed, the camera is capable of effecting exposure and development of a xerographic image well within the usable period of plate potential.

Since many changes could be made in the above con struction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings shall be interpreted as illus trative and not in a limiting sense.

What is claimed is:

l. A xerographic camera comprising a light tight boxlike structure having a lens element mounted in one Wall thereof, a shaft journaled in said structure for rotation about an axis parallel to the focal plane or" the lens element, plate holding means arranged on said shaft to support a xerographic plate in the focal plane of the lens element, a second shaft journaled in said structure for rotation about an axis parallel to the focal plane of the M r lens element, a xerographic plate charging unit fixed on said second shaft, a development'assembly supported on a second wall of the box-like structure, means to rotate the second shaft to move the charging unit into and out of charging relationship with a plate supported in the plate holding means, and means to rotate the first shaft to move the plate holding means to a position to place a plate supported therein in operative relationship to the development assembly.

2. A xerographic camera comprising a light tight boxlike structure having a lens element mounted in one wait thereof, hinged plate holding means arranged to support a xerographic plate in the focal plane of the lens element, a xerographic plate supported by the plate holding means, a xerographic plate charging unit mounted for movement about an axis parallel to the focal plane of lens element, a development assembly mounted on second wall of the box-like structure, said development assembly including inlet and outlet ports for powder particles and a gasket on the face thereof surrounding the effective area of the development assembly and said inlet and outlet ports, means to move the charging unit into and out of charging relationship with said xerographic plate, means to move the plate holding means to engage the xerographic plate with said gasket, whereby to form a developing chamber, and means for passing electrostatically charged powder particles through said developing chamber.

3. A xerographic camera comprising a light tight boxlike structure having a lens element mounted in the front wall thereof, a shaft journaled in the side Walls of said structure for rotation about an axis parallel to the focal plane of the lens element, plate holding means fixed on said shaft to support a xerographic plate in the focal plane of the lens element, a second shaft journaled in the side walls of said structure for rotation about an axis parallel to the focal plane of the lens element, a xerographic plate charging unit fixed on said second shaft, releasable detent means to retain the charging unit in an ineffective position adjacent the top wall of the structure, a development assembly supported on the bottom wall of the boxlike structure, means to rotate the second shaft to move the charging unit into charging relationship with a plate supported in the plate holding means and to restore the charging unit to its inefiective position, and means to rotate the first shaft to move the plate holding means to a position to place a plate supported therein in operative relationship with the development assembly.

4. A xerographic processing apparatus comprising a light tight box-like structure having a lens element mounted in the front wall thereof, a shaft journaled in the side walls of said structure for rotation about an axis parallel to the focal plane of the lens element, plate holding means fixed on said shaft to support a xerographic plate in the L focal plane of the lens element, a second shaft journaled in the side walls of said structure for rotation about an axis parallel to the focal plane of the lens element, a xerographic plate charging unit fixed on said second shaft, releasable detent means to retain the charging unit in an ineffective position adjacent the top wall of the structure, a development assembly supported on the bottom wall of the box-like structure, means to rotate the sec- 0nd shaft to move the charging unit into charging relationship with a plate supported in the plate holding means to form an electrostatic charge thereon and to restore the charging unit to its ineffective position, means to expose the plate to a light image to form an electrostatic latent image on said plate, and means to rotate the first shaft to move the plate holding means to a position to place a plate supported therein in operative relationship with the development assembly.

5. A xerographic processing apparatus comprising a light tight box-like structure having a lens element mounted in the front wall thereof, a shaft journaled in the side walls of said structure for rotation about an axis parallel to the focal plane of the lens element, plate holding means fixed on said shaft to support a xerographic plate in the focal plane of the lens element, a second shaft journaled in the side walls of said structure for rotation about an axis parallel to the focal plane of the lens element, a xerographic plate charging unit fixed on said second shaft, releasable detent means to retain the charging unit in an ineffective position adjacent the top wall of the structure, a development assembly supported on the bottom wall of the box-like structure, means to rotate the second shaft to move the charging unit into charging relationship with a plate supported in the plate holding means to form an electrostatic charge thereon and to restore the charging unit to its ineffective position, means to expose the plate to a light image to form an electrostatic latent image on said plate, means to rotate the first shaft to move the plate holding means to a position to place a plate supported therein in operative relationship with the development assembly, and means for developing the electrostatic latent image on said plate.

6. A xerographic charging, exposing and developing assembly comprising a light tight box-like structure having a lens element mounted in one wall thereof, hinged plate holding means arranged to support a xerographic plate in the focal plane of the lens element, a xerographic plate supported by the plate holding means, a xerographic plate charging unit mounted for movement about an axis parallel to the focal plane of the lens element, a development assembly mounted on a second wall of the box-like structure, said development assembly including a development electrode having inlet and outlet ports for powder particles and a gasket on the face thereof surrounding the effective area of the development electrode and said inlet and outlet ports, means to move the charging unit into and out of charging relationship with said xerographic plate, means for exposing said plate to a light image to form an electrostatic latent image thereon, means to move the plate holding means to engage the plate with said gasket, whereby to form a developing chamber, and means for passing electrostatically charged powder particles through said developing chamber.

References Cited in the tile of this patent UNITED STATES PATENTS 256,148 Lefeuvrier Apr. 11, 1882 2,588,675 Walkup et al Mar. 11, 1952 2,588,699 Carlson Mar. 11 ,1952 2,711,481 Phillips June 21, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,831,409 April 2 1958 William Eo Bixby et ale It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column; 2, line 42, for "short" read =--sort--; line 70, for "lot" read lest line '71, for umlsuahle read unusable-==-; column 3, lines 11 and 12, for "prooeduc'e" read -C-'proc'edure-'=-"; line 12, for "parctieal" read praetical g line 43, for "an" read -any line" 44, for "one" read -once' column 4, line 41, for fltype of" read --type e -3 line 63, for "plate" read =-=-plated=-==; column 6, lines 11 and 12, for "developement" read dsvelopment---=a Signed and sealed this 8th day of July 1958a (SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents UNTTED STATES PATENT OFFICE ERTIHATE GE RRETEN Patent No 2,83%409 April 22, 1958 William E0 Bixby et al0 Column 2, line 42, for "short" read ==sort-=--; line '70, for "lot" read. lost line '71, for "unusuable" read =-=-unusable-*= column 3, lines 11 and 12, for "proceducie" read procedure line 12 for "parctical" read. praeticalg line 43, for "*arp re'ad line- 44, for "one" read; oncecolumn 4, line 41, for l'type of" read bype a -=3 line 63, for "plate" read ===-plated==; column 6, lines 11 and 12, for "developement" read" '-=deve'lopment-== Signed and sealed this 8th day of July 1958,

(SEAL) Attest:

KARL Ha AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents

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Referenced by
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US3028799 *Mar 8, 1957Apr 10, 1962Franklin Keller DanielApparatus for electrophotographic printing
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US3091219 *Dec 24, 1958May 28, 1963Xerox CorpXerographic developing apparatus
US3182573 *Aug 11, 1961May 11, 1965Xerox CorpMasked plate xerography
US3697173 *Mar 10, 1971Oct 10, 1972Matsushita Electric Ind Co LtdElectrophotographic processor camera
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US5605777 *Nov 27, 1995Feb 25, 1997Ricoh Company, Ltd.Adhesive state of toner on transfer paper sheet is changed to an unstable state; separating; drying
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US5896612 *Mar 13, 1997Apr 27, 1999Ricoh Company, Ltd.Method and apparatus for removing image forming substance from image holding member
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Classifications
U.S. Classification399/135
International ClassificationG03G15/26, G03G15/00
Cooperative ClassificationG03G15/266
European ClassificationG03G15/26C