US2550738A

US2550738A - Apparatus for applying powder to electrophotographic plates

Info

Publication number: US2550738A
Application number: US137169A
Authority: US
Inventors: Lewis E Walkup
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1950-01-06
Filing date: 1950-01-06
Publication date: 1951-05-01
Anticipated expiration: 1968-05-01

Description

L. E. WALKUP May 1, 1951 APPARATUS FOR APPLYING POWDER TO ELECTROPHOTOGRAPHIC PLATES Filed Jan. 6, 1950 l6a I4 24 a9 32 a n, Fl.

4 y? 34 I6 Z8 Z3 INVENTOR. Lgwas E. WALKUP BY H-v-vw Patented May 1, 1951 APPARATUS FOR APPLYING POWDER T ELECTROPHOTOGRAPHIC PLATES Lewis E. Walkup, Columbus, Ohio, assignor, by mesne assignments, to The Haloid Company, Rochester, N. Y., a corporation of New York Application January 6, 1950, Serial No. 137,169

7 Claims. (01. 95-1.9)

This invention relates to electric photography and to apparatus for supporting an electrophotographic plate while an electrostatic image formed on the plate is developed by flowing electroscopic developing p wder over the image and while the plate is cleaned after development and transfer of the image. More particularly this invention relates to a tray for holding a surface capable of retaining such an electrostatic image and for holding and for permitting the selective application of the electroscopic developing powder and of the cleaning powder used respectively in developing such an image when it is flowed across it and in cleaning the electroscopic powder from the image bearing surface after development of the image.

When making copies by electrophotcgraphy, the customary practice is to charge electrostatically a suitable sensitive surface such as a photo conductive insulating layer coated on a conductive backing as disclosed in Carlson Patent #2,297,691, issued October 6, 1942. This surface or plate is then exposed to a pattern of light and shadows which form an electrostatic image on the photosensitive surface which is a reproduction of the object desired to be reproduced. lhe plate is then dusted with electroscopic developing powder to form a powder image thereon corresponding to said electrostatic image and the powder image is transferred to a paper or other sheet following which any electroscopic powder remaining on the plate is cleaned by means of suitable cleaning powder which is dusted over the plate.

This invention relates to apparatus for performing the development of such an image by dusting it with an electroscopic developing powder and for cleaning the residual powder left on the image bearing surface after the image has been transferred to another surface and has for a specific object thereof to afford a conveniently operable apparatus in which the plate can be positioned after charging and exposing to receive the electroscopic developing powder that is cascaded over the plate to form the powder image from the electrostatic image, and also to receive the plate after the powder image has been transferred to permit cascading over the plate a clean ing powder that acts to remove any adhering electroscopic powder from the plate to prepare the plate to receive another electrostatic charge.

More specifically the invention has for its object to afford a tiltable or rockable plate support provided with a powder receptacle at each end communicating with the surface of the support and or the electrophotographic plate positioned thereon, the powder receptacles each having a movable closure that is selectively operative to permit movement of the powder from the selected receptacle over the plate upon oscillating the plate support.

Another object of the invention is to provide an apparatus of the character mentioned such that the receptacle at one end or" th plate support may be supplied with electroscopic powder and the receptacle at the other end of the support supplied with cleaning powder, thus enabling the plate to be positioned in the supportto haveapplied to it either electroscopic powder immediately after the charging operation, or cleaning powder after the powder image has been removed from the plate, the character of the powder operation depending on which receptacle closure is opened after the plate is positioned.

An additional object of the invention is to at ford a structure which the powder, either electrosccpic or cleaning, is effectively confined within its receptacle except when being applied to the surface of the electrcphotographic plate, the mechanism enabling the powderlto be easily returned to its receptacle after the plate dusting operation is completed and to be retained therein so as not to interfere with a subsequent operation when the alternative powder is applied to the plate.

For a better understanding of this invention, together with other and further objects thereof, reference is now had to the following description taken in connection with the accompanying drawing, and the scope of the invention will be pointed out in the appended claims.

In the accompanying drawing, Figure 1 is a top view of an apparatus constructed in accordance with a preferred embodiment of the invention. Figure 2 is a sectional elevation of the apparatus of Figure 1 taken along the line 2--2; and Figure 3 is a ectional view of the apparatus of Figure 1 taken along the line 3-3. Similar elements in each figure are identified by identical numbers.

Referring now to the drawing, a pair of flanges l are fixedly attached, as by pins 2, to an elongated cylindrical shaft 3 which is suitably horizcntally mounted for pivotal movement in a pair of bearings 4 set in the end portion of a pair of spaced apart pedestals 5.

An L-shaped crank arm may be attached, as by pin l, to one end of the shaft 3 so that the shaft may easily be rotated about its horizontal axis, and pre"erahly a portion of the crank arm 6 is adjacent to and extends parallel talent in spaced apart relationship with one of the pedestals 5 so that a thumb screw it may protrude through a suitably threaded opening 8a, in the crank arm 9 and thereby hold the crank arm 5 and thereby the shaft 3 and the flanges i in a predetermined position with respect to the pedestals 5 when the thumb screw is extended into a notch Sb in the adjacent pedestal or into a washer between the adjacent pedestal 5 and the parallel portion of the crank arm 6.

This predetermined position at which the flanges l are held by the thumb screw is such that a base member or bottom wall 9 of plate supporting tray ill to which the flanges l are attached, as, lor example, by the bolts l i, is kept substantially level horizontally with a horizontal support platform it on which the pedestals 5 may be suitably mounted as by bolts 93.

The base member 9 of the plate supporting tray It) forms a substantially fiat surface on which an electrophotographic plate it may be positioned to be subjected to a powder dusting operation by rocking or oscillating the tray it attached to the flanges I back and forth on the pedestals 5 about a horizontal axis of oscillation corresponding to the axis of the shaft 3. The maximum angle of oscillation is determined by the stop lb which may be a part of one of the pedestals s or which, as illustrated, may be a metal strip projecting angularly from one of the pedestals 5 which engages one of the flanges i when it is rotated to a predetermined angle about the axis of the shat t 3, preferably at least a swing of 50 should be permitted.

Suitable washers 5a may be provided between each of the flanges l and each of the pedestals 5 and between the crank arm 6 and the pedestal 5 which it is adjacent to for insuring a close fit and for permitting smooth movement.

A pair of substantially flat elongated base plates it are mounted, as by welding, in spaced apart relationship at opposite ends of the base member 8 and extend across the base member s parallel to the horizontal axis of oscillation thereof to form the base of a pair of elongated coinpar'tments l l which extend across the tray ill parallel to the axis of oscillation thereof, one of the compartments being at one end of the tray is and the other of said compartments being at the other end of the tray it.

The base plates is extend across the base member 9 on the upper surface thereof and leave in the area between them a central portion of the base member 51 which is outlined by the shoulders of the base plates is and the strip members Isa extending between the plates it to form a recessed portion in the center of the tray Ill. This central portion is open from the top to per mit a cleaning powder is and a developing powder 19 to be introduced respectively into one or the other of the compartments ll which are on opposite sides of this central portion which portion is adapted to receive and hold the electrophotographic plate M.

An opening 23 is provided in the base member 9 in the central portion thereof through which an object may be inserted to lift the electrophotographic plate from its seat in the recess formed by the base plates it and strip members lea. As illustrated, such an object may be a cam 2i operated by a lever arm 22 mounted on the under side of the base member 9 of the tray iii in the bearings 23.

Each of the compartments ll has a front wall 24, a top wall 25, a back wall 25, and side walls Eli 35, which latter two walls may be attached as by screws 27 to the base member 9 of the tray it, or, as one alternative, the back and side walls may suitably attached to the base plates it. These walls form a closed compartment at either end of the tray ill except that the front wall 24 is cut away at the portion of the compartment where the front wall 2d would contact the base plates it to form an opening 25 which extends across the tray iii for at least the length of the electrostatic image bearing portion of the electrophotographic plate i i and permits the pew clers l3, iii to flow freely from the compartments l'l across the central portion of the tray iii. The back wall 25, front wall 2 and the opening 23 extend lengthwise across the tray is in parallel relationship with the aforementioned horizontal axis of oscillation.

A pair of closure walls 29 selectively movable from open to closed position are spaced apart from andparallel to the front walls 2% and back walls 2% and divide each of the compartments l'i into a pair of receptacles 32!, 35, one of which, for example receptacle 353, is outlined by back wall 25, base plates 55, top wall 25, the side walls and the closure wall as, and forms a completely enclosed receptacle in each of the compartments ii in which the powders l3 and it can be respectively confined when the closure wall 29 is in closed position; and the other of which, receptacle 35, opens onto the central portion of the tray ill through the opening 23.

The movable closure Walls 29 are fixed in place within the compartments ll by means of the guides 32 which are afiixed to the side walls 35 of each of the compartments ll. As illustrated, each wall 23 is slidable between the guides 32 and may be selectively moved to open or closed position by sliding upward between the

guides

32 and 1 through a slot 33 in the top Wall 25.

When either of the walls 29 is in open position, an unobstructed surface is provided between the the interior of the respective powder receptacle fill and the central portion of the tray iii in the recessed portion of which the electrostatic plate it is positioned; the recessed central portion of the tray l9 being of sufficient depth that the electrostatic inage bearing portion of the plate it forms a level surface with the upper faces of the base plates iii. Means (not shown) for holdthe walls 29 in open or closed position could be provided; and rather than the slot 32 through the top wall 25, the doors could open by sliding lengthwise through the guides 32 or in another suitable manner.

The side wall 35 extends above the base member 9 of the tray it and above the electrophotographic plate l l when positioned within the recessed portion of the tray it} at opposite sides adjacent to the powder opening 28, the Walls 35 thereby confining the powder within the tray ll] when the tray it is rocked on the pedestals 5 with one of the closure walls 253 in its opened position.

It will be understood that the parts just described are mechanical details in the formation of the complete structure, which may be variously designed and connected without departing from the invention.

To operate the apparatus as has been described to develop an electrostatic image and to clean the image bearing surface, the cleaning powder [8 and the developing powder it are individually confined in the powder receptacles 3% at each end of the tray ill. The receptacle 3!) at one end of the tray 18 containing the cleaning powder 18 which may be a granular material, such as is disclosed in Copley Patent #'2,484,782 and the receptacle at the other end of the tray containing the developing powder 19 which may be a powdercarrier mixture as disclosed in the copending application of Lewis E. Walkup, Serial #55545, filed October 20, 19%, entitled Developer for Electrostatic Images.

After the electrophotographic plate I4 is electrostatically charged and exposed to a pattern of light and shadows to produce an electrostatic image on the photosensitive surface which is a reproduction of the object to be copied, it is placed within the recessed portion of the plate support or tray H] with the electrostatic image bearing surface facing upwardly, and the closure wall 29 to the compartment ll containing the eveloping powder receptacle 3B is opened.

The support or tray i0 can then be rocked or oscillated about its axis of oscillation when the thumb screw 3 is removed from the notch 8b so that the developing powder receptacle 30 passes above and below the axis of oscillation so causing the developing powder :9 to flow or cascade alternately in opposite directions over the exposed surface of the electrophotographic plate l4 so that the developing powder 19 adheres to the electrostatic image on the plate. During the dusting operation, the compartment I! opposite to the compartment ll containing the electroscopic developing powder receptacle 30 receives the powder when it flows in that direction and its front wall 2 and side wall 35 prevent the overflow of the powder over the edges of the tray H! and confine the dust while its closure wall 25 prevents the developing powder 59 from mixing with the cleaning powder i8 which is enclosed in its respective receptacle 39. When the dusting operation for development of the image is completed, the surplus developing powder '9 that is not retained by the electrostatic image on the plate hi is permitted to flow back into its receptacle 38 by holding the tray [0 in inclined position with the developing powder receptacle 30 below the axis of oscillation and with its 010- sure wall 29 in open position, and after the powder is all returned to the receptacle 31!, the closure 29 is moved to closed position and the plate I4 is removed from the support by turning lever arm 22 operating the cam 21.

After the powder image is ransferred from the plate 14 to a sheet of paper or other surface, it is desirable to clean the plate thoroughly before subjecting it to another charge and exposure, and this is accomplished by again placing the plate M in the tray as already described and opening the closure wall or door 29 to the cleaning powder receptacle 30 at the other end of the support, permitting the cleaning powder 18 contained in the cleaning powder receptaole 3D to flow back and forth over the plate l4 when the tray ill is rocked or oscillated on the pedestals 5. After several such operations, the plate I4 is cleaned and the cleaning powder l8 can be permitted to flow back into its receptacle, following which the door to the cleaning powder receptacle 38 is closed, and the electrophotographic plate can be removed from the support to be recharged for receiving another image.

While I have described and illustrated a particular embodiment of my invention, it will be understood that various omissions, substitutions, and changes in the forms and details of the device illustrated and in its use and operation may 8 be made by those skilled in the art without departing from the broad spirit and scope of the invention, and I, therefore, contemplate by the following claims to cover any such modifications as fall within the true spirit and scope of the invention What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for applying powder to an electrophotographic plate comprising an oscillatory support on which the electrophotographic plate can be mounted, a powder receptacle at one end of the support extending thereacross, said support extending into and forming the bottom for said receptacle and having a recess spaced from said receptacle in which the electrophotographic plate can be positioned with its top surface flush with the top surface of the support, the re ceptacle having an opening in its inner wall permitting movement of powder from the receptacle over a plate positioned on the support, powderconfining means extending along the sides of the support, and a slidable closure for said opening mounted between guide members and slidable between an and a closed position.

2. Apparatus for applying powder to an electrophotographic plate comprising an oscillatory support on which the electrophotographic plate can 'be mounted, a powder receptacle at each end of the support extending thereaoross, said support extending into and forming the bottom for said receptacle and having a recess spaced from said receptacle in which the electrophotographic plate can be positioned with its top surface flush with the top surface of the support, one of said receptacles being adapted to contain developing powder and the other of said receptacles being adapted to contain cleaning powder and each receptacle having an opening in its inner wall permitting movement of powder from the receptacle over a plate positioned on the support, powder-confining means extending along the sides of the support, and a slida'cle closure for said opening mounted between guide members and slidable between an open and a closed position.

3. Apparatus for supporting a surface capable of retaining an electrostatic image and for holding and permitting selective application of powders for developing said image and for cleaning said surface after development of said image when flowed across said surface comprising, a base member having a recessed central portion for holding said image bearing surface flush with the surface of the base member, said base member being mounted on a horizontal axis of oscillation, a first elongated compartment on said member extending parallel to said axis and beyond one edge of the recessed portion for said image bearing surface, a second elongated compartment on said member extending parallel to said first compartment beyond the opposite edge of the recessed portion for said image bearing surface, each of said compartments opening onto said central portion for at least the length of said recess, and dividing means slidably mounted and movable from opened to closed position for separating each of said compartments into a pair of receptacles, one of which is completely separated from the other when said dividing means is in closed position.

4. Apparatus for supporting a surface capable of retaining an electrostatic image and for holding and permitting the selective application of powders for developing said image and for cleaning;,said:surface.afterzdevelopment of 'saidJimage:

when: flowed across. saidsurface comprising, a base member; having a recessed. central portion for; holdingsaidimage bearing surface. therein flushwith the surface of the base member, said base member being mounted on a horizontal-axis of oscillation and stops mounted at said axis to limit the angle of rotation around the axis,

a first elongated compartment on said member extending parallel to said axis beyond one edge of said recessed portion, a second elongated compartment on said member extending parallel to said first compartment beyond the opposite edge of said recessed portion, each of said chambers opening onto said central portion for at least the length of said recessed portion, powder confining means extending approximately perpendicular to eachcf said compartments andraised above the surface of said image bearing surface oneach other side of said surface, and dividing means slidably mounted and movable from opened to closed position for separating each or said compartments into apair of receptacles, one of which is completely separated from the other when said dividing means is in closed position thereby to. isolate the contents of said completely separated receptacle so that the contents of one or" said receptacles only can be flowed.

across said central portion when said base memher is oscillated about 'said axis.

5. Apparatus for supporting a surface capable of retaining an electrostatic image and for holding and permitting the selective application of powders for developing said image and for cleaning said surface after development of said image when flowed across said surface comprising, a base member having a recessed central portion for holding said image bearing surface flush with the surface of the base member, said base member being mounted on a horizontalv axis of oscillation and stops mounted at said axis to limit the angleof rotation around the axis, a first elongated compartment on said member extending parallel to said axis beyond one edge of said recessedportion, and containing electroscopic developing powder, said compartment opening onto said central portion for at least thelength of said image bearing surface, a first dividing means slidably mounted and movable upwardly to open and downwardly to closed e position for separating said compartment into a pair of receptacles one of which is completely separated from the other when said dividing means is in closed position thereby to permit isolation of said developing powder from said central portion, a second elongated compartment on said member extending parallel to said, axis beyond the opposite edge of saidrecessed portion and containing a cleaning powder, said second compartment opening onto said central portion for at least the length of said image bearing surface, and a' second dividing means slidably mounted and movable from open to closed position for separating said second compartment,

into a pair of receptacles, one of which is completely separated from the other when said dividing means. is in closed position thereby to permit. isolation, of: said cleaning powderfrom.

said, central portionandfrom said electrosoopic.

powder; during development. of. saiduima c. when;

said base, memberv is. oscillated with said first dividingmeans at open position.

6. Apparatus for supporting a surfacecapabletom wall for holding said surface flush with the, surface of the'bottom Wall and surrounded byraised end and side walls, said tray having a hOI'i-r zontal axis of oscillation parallel to said end walls,

apair of closure wallsselectively slidable upward ly to open and downwardly toclosed position and extending parallel to said endwalls, and spaced apart therefrom atv either end of saidtray, so.

forming withsaid end wallsapair of receptacles,

one of said receptacles enclosing developing, powder. andthe other of said receptacles enclose ing cleaning, powder, and means for mounting saidtray so that it can be rocked, back and ,forth about said axis of oscillation so permitting powder; tobe applied to said surface from said. re,- ceptacle having its closure wall in open position, thepowder in said other receptacle having its closurewall in closed position being confined and stopsmounted attheaxisto limitthe angle of rotation.

7. Apowder developing and cleaning tray for an electrophoto-graphic plate comprising, in combination abottom wall enclosed with sidewalls and endwalls, apair of slidably mounted closure wallsspaced apart from and parallel to said end walls to provide a pair of elongated powder receptaclesextending along the end wallsof said tray, recessed means for supporting an electro.-, static image bearing plate faceup onsaid tray andflush with the bottom wall thereof in the area providedbetween said receptacleseaehof,

said. closure walls being slidably movable from. a.closed position to an open position to provide.

any unobstructed powder flow surface between the interior of its respective receptacle and. the mounting area of ,said electrostatic image bearing plate, whereby selective flow of two separate.

powder materials over said image bearing plate may be effected by selectively opening, said 010- sure walls and tilting said tray about, an axis parallel to said end walls.

LEWIS' E. WALKUP.

REFERENCES CITED The following references are of record in the filBrOfl this patent;

UNITED. STATES PATENTS Number" Name Date 8,519 Taylor Nov. 11, 1851 1,199,028 Cornwall Sept. 19, 1916 2,225,752 Mertes et al Dec. 24, 1940 FOREIGN PATENTS.

Number Country Date 427,844 Germany Apr. 15, 1926