US2588675A

US2588675A - Electrocopy apparatus

Info

Publication number: US2588675A
Application number: US63922A
Authority: US
Inventors: Lewis E Walkup; Harold E Copley; Walter A Beckdahl
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1948-12-07
Filing date: 1948-12-07
Publication date: 1952-03-11
Anticipated expiration: 1969-03-11
Also published as: CH286151A; DE863297C; GB695450A

Description

March 11, 1952 E. WALKUP ET AL ELECTROCOPY APPARATUS 4 Sheets-Sheet 1 Filed Dec. '7, 1948 6. ATTORNEY March 11, 1952 L. E. WALKUP ET AL ELECTROCOPY APPARATUS 4 Sheets-Sheet 2 Filed Dec. '7, 1948 INVENTORS Lewis E. Wolkup v Harold E Copley ix 53F BY alter AvBeckdohl we; ATTORNEY.

March 11, 1952 E. WALKUP ET AL 2,588,675

ELECTROCOPY APPARATUS Filed Dec. 7, 1948 4 Sheets-Sheet 5 INVENTORS Lewis E. Walkup Harold E. Copley Walter A. Beckdohl WF M a ATTORNEY March 11, 1952 1.. E. WALKUP ET AL ELECTROCOPY APPARATUS 4 Sheets-Sheet 4 Filed Dec. '7, 1948 ad; ATTORNEY Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE ELECTROCOPY APPARATUS Lewis E. Walkup, Harold E. Copley, and Walter A. Beckdahl, Columbus, Ohio, assignors, by mesne assignments, to The Haloid Company, Rochester, N. Y., a corporation of New York Application December 7, 1948, Serial No. 63,922

9 Claims. 1

This invention relates to electrocopy apparatus for making copies by electrostatically charging a photoconductive insulating surface on a plate, exposing the charged surface while positioned over the matter to be copied, dusting the latent electrostatic image thus produced with electroscopic powder to form a powder image which is then transferred and fixed to a paper or other support, and it has for its purpose to afford a practical and efficient construction for carrying out this procedure in making contact copies of printed or typewritten matter, drawings, maps, photographs, or other records quickly and economically.

More particularly, the invention is intended to afford a compact, portable apparatus of simple and economical construction, that can be readily operated in a small space to perform all the required charging, exposing, powder-dusting, and transfer operations required in making an electrocopy.

Still another object of the invention is to afford a cabinet of practical construction that can be operated easily and quickly to charge electrostatically the sensitized plate carrying the photoconductive insulating layer when the plate is in one position in the cabinet, to expose the plate over the matter to be copied when in another position in relation to the cabinet, and to transfer the powder image from the plate to a paper support when in another position in the cabinet, the plate being readily positionable in the several positions necessary for carrying out the charging, exposing, and transfer operations.

An additional object of the invention is to provide a simple and practical form of powder-dusting mechanism which can readily be employed in conjunction with the charging, exposing, and transfer cabinet, and which can be operated to apply electroscopic powder to the electrostatic image on the plate and to apply cleaning powder to the plate for removing excess electroscopic powder therefrom after a transfer operation is completed, preparatory to using the plate for making another copy.

Specifically the invention has for another purpose to afford a cabinet having lighting means therein for exposing the plate to produce an electrostatic image, and an electrostatic charging unit movable across the cabinet to charge the plate when the latter is in one position in the cabinet above the charging unit and to transfer a powder image from the plate to a paper support when the plate is in another position in the cabinet below the charging unit, ex-

posure being effected when the plate is positioned on top of the cabinet to receive light therefrom through a transparent panel on which is arranged the matter to be copied, these parts being constructed and related in a manner that enables a quick and efficient performance of the several steps.

To these and other ends, the invention consists in the construction and arrangement of parts that will appear clearly from the following description when read in conjunction with the accompanying drawings, the novel features bein pointed out in the claims following the specification.

In the drawings:

Fig. 1 is a perspective view of a cabinet, partially broken away, showing the movable chargin unit in a position intermediate the ends of the cabinet as when charging the plate or transferring a powder image from the plate to the paper support;

Fig. 2 is a transverse vertical sectional view through Fig. 1;

Fig. 3 is an enlarged detail vertical sectional a view taken transversely through one end of the charging unit, showing the busbar on which it slides;

Fig. 4 is a top plan view of the cabinet illustrated in Figs. 1 and 2, with the top wall removed and showing the electrical lighting and controlling means and the charging unit;

Fig. 5 is a perspective view showing the plate with its photoconductive insulating surface and the supporting frame therefor, with the light shield partially removed;

Fig. 6 is a perspective view, partially broken away, showing the means for dusting electroscopic powder on the plate, which is illustrated in clamped position on a powder tray, the latter being removed from its support;

Fig. 7 is a perspective view showing a powder tray in operative position on its support with a plate clamped therein ready for dusting;

Fig. 8 is a view similar to Fig. 7, looking toward the opposite end of the powder tray, and showing the clamping devices elevated in the position assumed when a plate supporting frame is to be inserted or removed, and

Fig. 9 is a diagrammatic view of the electrical circuit and controlling devices.

Referring more particularly to the drawings in which like reference numerals refer to the same parts throughout the several views and to Fig. 5, the structure includes a metal conducting plate that is provided with a photoconductive insulatductive insulating surface of the plate and protect the same from light.

In making a copy of printed or typewritten matter, a drawing, map, photograph, or other subject, it is necessary first to charge the plate I electrostatically, thereafter to expose the charged photoconductive surface while positioned over the subject to light to form a latent electrostatic image on the plate, subsequently dusting the electrostatic image with electroscopic powder to form a powder image, which is then transferred to a paper or other support and affixed in any suitable fashion, and the structure of the cabinet and parts by which these several operations are effected will now be described in detail.

' Referring to Figs. 1 and 2, the cabinet includes a bottom wall 6, side walls 7, and a top wall 8 that is provided with a central glass or transparent panel 9 on which the subject or matter to be copied is held in any suitable way with the printed matter facing upwardly when the charged plate is superposed thereover for exposure, as will be described presently. ll designates leaf springs mounted on the top wall 8 adjacent to the glass panel 9 for elevating the supporting frame 2 when the latter is positioned over the glass panel to expose the charged plate in registry therewith, the springs H raising the supporting frame 2 to permit removal of the light Shield 3 after the supporting frame and plate are in position, after which the supporting frame 2 is manually depressed to effect exposure, it being understood that when light is projected from the cabinet through the glass panel 9 and through the subject which is positioned on the glass panel facing upwardly, the supporting frame 2 fits closely around the glass panel 9 resting upon springs l l, and the photoconductive surface of the plate faces downwardly and is brought into juxtarelation with the matter to be copied resting on the transparent panel 9.

Before exposing the plate, it is necessary to charge the photoconductive insulating surface electrostatically, and after the powder image is formed on the plate, it is necessary to transfer the same to a paper support electrostatically, and these charging operations are performed within the cabinet and accomplished by electrostatic charging instrumentalities including a charging unit slidable endwise of the cabinet and comprising a plate or shield I 2 of metal or other stiff material having a series of charging wires l3 mounted above and spaced from its upper surface between the blocks M of any suitable insulating material and operable to spray a charge on the photoconductive insulating surface of the plate I and another series of spaced parallel charging wires extending endwise of the plate I2 below the latter and spaced therefrom between the insulating blocks [6, and operable to effect transfer of a powder image from the plate to a paper support or transfer sheet.

The charging wires I3 and I5 are preferably spaced one-half inch from each other and onehalf inch from the plate I 2 which acts as a shield between the two sets of charging wires 13 and I5 and in order to enable sliding the char ing unit endwise of the cabinet, one end of plate l2 has fixed thereto a tongue ll that slides in a suitable guideway provided on the adjacent side wall I of the cabinet while the opposite end of plate l2 carries an insulating block that is provided with metallic bushings l8 slidable on a busbar l9 suitably fixed in the cabinet and extending endwise thereof in proximity to the adjacent side wall I, whereby the charging unit is movable endwise on busbar [9. The busbar I9 is connected in suitable fashion to the electrical circuit while the charging wires I3 and I5 are connected in series by conductor 23 and to bushing [8 by conductor 2! and thus through busbar H! to the electrical circuit, and the charging unit is moved endwise of the cabinet manually by an operating finger 22 attached to one end of the charging unit and extending vertically through a slot in the top wall and in the guideway immediately thereunder, see Fig. 2, the operating finger projecting upwardly above the top Wall of the cabinet where it is accessible for moving the charging unit endwise of the cabinet.

To charge the plate, the supporting frame 2 is inserted into the cabinet through the slot 23 at the front end thereof, see Fig. 1, into guideways 24 formed in rails fastened to the side walls I of the cabinet immediately above the charging unit. When the supporting frame 2 is thus inserted to charge the photoconductive insulating surface on the plate, it must be inserted so that when in position in the cabinet the slot 4 is at the front end of the cabinet, permitting the light shield 3 to be inserted into the supporting frame 2 after the electrostatic charge is imposed on the plate.

When the supporting frame 2 is inserted to charge the plate I, the supporting frame is positioned so that the photoconductive insulating surface I faces downwardly toward the charging unit. The supporting frame and plate close the cabinet against light during the charging operation at which time the lighting circuit is open. After theelectrostatic charge is imposed on the plate, the light shield 3 is inserted into the supporting frame 2 before removing the latter from the cabinet.

The charged plate is then exposed by closing the lamp circuit, placing the supporting frame 2 on top of the subject and glass panelwith the charged plate facing downwardly, removing the light shield, and pressing the supporting frame 2 downwardly against the springs ll, after which the charged and exposed plate is dusted with electroscopic powder to form a powder image in the manner that will be described presently, and when the powder image has been thus formed on the plate, the supporting frame 2 with the light shield 3 removedthis being unnecessary after the powder image is formedis again inserted into the cabinet through slot 25 and into guideways 25 formed in rails mounted on the side walls 1 of the cabinet under the electrostatic charging unit. The supporting frame 2 is inserted with the powder image facing upwardly toward the charging unit in order to effect transfer of the image onto a paper or other transfer sheet which is positioned above and resting on the powder image when the supporting frame is inserted into the cabinet for the transfer operation.

When the plate is inserted into the cabinet above the charging unit for charging, the plate l2 with the charging wires l3 and 15 extending transversely across the plate is moved endwise .of the cabinet back and forth and an electrostatic charge is sprayed onto the photoconductive insulating surface by the wires I3, and during the transfer operation when the plate is .positioned under the charging unit with the powder image and paper resting thereon facing upwardly, the charging unit is moved endwise of the cabinet and an electrostatic charge sprayed from wires I5 effects transfer of the powder image from the plate onto the superposed paper, after which the supporting frame .2 and paper transfer sheet are removed, and the powder image afiixed to the paper as by fusing between heated plates or otherwise, by the use of volatile solvents, or in any other suitable way.

Dusting of the charged photoconductive insulating surface with electroscopic powder is preferably effected by the mechanism shown in Figs. 6 to 8, including a base 21 with trunnion bearings formed by ears 28 having groovesor notches 29 formed therein to receive trunnions 3| carried by the side rails 32 of a tray within which is arranged the electroscopic dusting powder 33. The powder tray is provided with means for clamping the supporting frame 2 thereagainst, such clamping operation being effected by a frame including cross-rods :34 pivotally mounted in brackets 35 and carrying rails 33 having rubber or elastic pads 37 ontheir bottom edges which contact the outer surface of the plate and supporting frame 2 to clamp the latter against the tray, while 38 designates any convenient form of releasable catch for holding the rods 34 in their clamping position, as illustrated in Fig. 6.

To effect the powder-dusting operation and form a .powder image on the plate after the latter has been charged electrostatically and exposed, the plate with the light shield in position is positioned on the powder-dusting tray in the manner shown in Fig. 6 with the photoconductive insulating surface facing inwardly toward the powder. The clamping frame is then swung downwardly and the catches 38 engaged over the ends of rods 34 to hold the supporting frame 2 in clamped position. The light shield is then removed and the dusting tray rocked on the supporting trunnion bearings 23 by lifting the free end of the tray upwardly and swinging it over until it is in reverse position or above the sup porting frame. The powder in the tray will then fall against the photoconductive insulating surface I, and by moving the dusting tray upwardly and downwardly several times, the powder is caused to flow across the plate and is evenly distributed over the electrostatic image to which it adheres. Two sets of trunnion bearings are provided on the base 21 to permit the use .of two similar dusting trays, one tray being filled with cleaning powder of any suitable character which is used to clean the plate and remove excess or adhering electroscopic powder after the transfer operation is completed, preparatory to using the plate for another copying operation.

In order to produce the latent electrostatic image on exposure of the charged plate, the cabinet is provided with a series of lamps 33 arranged on "the bottom wall 6 in any desirable manner. The lamps 39 are 7 watt frosted bulbs arranged to give even distribution of light over the glass panel, although a single lamp with a suitable filter or any source of light may be used that gives uniform distribution of light over the subject. 'The lamps are controlled 'by a suitable timer 4i and switch button-42 that are manually operated to light the lamps .for a predetermined periodof time before exposing the plate to .the subject. 43 designates a resistor that may be used in the circuit, 44 is a transformer, 45 a suitable rectifier, :and 46 is a microswitch, see Figs. 1 and 4, located in the path of the slidable plate l2 above the charging unit and acting automatically to open the charging circuit when the charging unit is in its inoperative position at one end of the cabinet, thus insuring opening the charging circuit except when the charging unit is being moved endwise of the-cabinet to charge the plate or to effect transfer of the powder image. 41 designates a conducting contact at the -rea.r of the cabinet beneath the transparent top panel 9 and including portions arranged to be engaged by the conductive plate I when the latter is inserted into the'cabinet for-charging the plate or for transferring a powder image, in order to complete a circuit through the conductive plate. For charging the .plate, or transferring the powder image, a rectified A. C. current of 6000 volts and about milli-ampere can be used satisfactorily. The lamps 33 are arranged in parallel and timer 4| in series with the lamps, while the circuit to the charging unit includes the switch 46, transformer 44, rectifier 45, charging wires [3 and I5, and the grounded shield or plate [2, all as shown.

The operation of the apparatus briefly is as follows:

Assuming the charging unit to be at the back end of the cabinet in which position it engages switch 46 and opens the charging circuit, the light shield 3 is removed from supporting frame 2 and the latter is inserted through the slot 23 at the front end of the cabinet with the photoconductive insulating surface I facing downwardly toward the charging wires l3 and the slot 4 at the front end of the cabinet when inserted into the guideways 24. Thereupon the operating finger 22 is engaged and moved endwise of the cabinet, actuating the charging unit away from switch 46, which immediately closes the charging circuit and causes an electrostatic charge to be sprayed from charging wires l3 onto the photoconductive insulating surface I of the plate. This is accomplished by moving the charging unit to the front end of the cabinet and back to its initial position, after which the light shield 3 is inserted through slot 4 into the supporting frame 2 to protect the charged-surface from light and the supporting frame is removed from the cabinet.

Following this, the printed, typewritten, or other matter to be copied is placed upon the transparent panel 9 at the top of the cabinet with the printed matter facing upwardly, after which the timer 4| is set and switch button 42 operated to close the lighting circuit and light the lamps 39 for a predetermined length of time. The supporting frame 2 is positioned over the transparent panel 9 in registry therewith and resting upon leaf springs I I, with the photoconductive insulating surface I and light shield 3 facing downwardly toward the subject to be copied. When in position on the springs H, the light shield 3 is removed and the supporting frame 2 pressed downwardly against the tension of springs II to bring the charged photoconductive insulating surface I in close proximity to the subject, which is resting on the glass panel 9.

It will be understood that during exposure, the electrostatic charge is drained away from the insulating surface onto the "conductive plate in those areas where light strikes the charged insulating surface, and in the areas where light is prevented from striking the charged surface by reason of the black or dark areas of the matter being copied, the charge remains on the plate and thus forms a latent electrostatic image. The light shield 3 is then reinserted into supporting frame Zto protect the latent image, and the supporting frame 2 removed from the cabinet and placed in a powder-dusting tray and clamped therein, with the electrostatic image facing toward the interior of the tray. The light shield 3 is then removed and the tray is rocked as already described to apply electroscopic powder over the entire surface of the photoconductive surface uniformly and thus form a powder image.

The supportingframe 2 with the powder image thus formed on the plate is then removed from the dusting tray after unclamping. it, and a sheet of paper or other transfer material laid in the supporting frame in contact with the powder image. The supporting frame with the sheet of transfer paper resting on the powder image is then insertedthrough slot at the forward end of the cabinet into the guideways 26, until it is disposed entirely within the cabinet, with the powder image and transfer sheet facing upwardly toward the charging wires I5. The operating finger 22v is then engaged and moved endwise of the cabinet to move the charging unit toward the front end of the cabinet and back to its initial position, causing an electrostatic charge to be sprayed from charging wires l5, which acts to transfer the powder image from the plate onto the sheet of transfer paper. a

After removal of the supporting frame 2 from the cabinet, the transfer paper with the powder image held thereon electrostaticall is subjected to a suitable heating or fusing operation to affix the powder image, or the latter may be permader from the plate which is then ready for an other copying operation. i

If desirable, the upper charging wires I3 may be omitted from the plate lz, in which case the electrostatic charging and transfer operations are both performed by the lower charging wires l5, and during such charging operation, the insulating surface of the plate faces upwardly and the charging operation is performed in a dark room, or a suitable cover is positioned overthe trans,- parent panel 9. While the invention has been described with reference to the structure shown herein, it is not limited to the structural details set forth, and this application is intended to cover such modifications or departures as may come within the; purposes of the improvements or the scope of the following claims.

We claim: v 1. Electrocopy apparatus comprising a cabinet having a top wall, a transparent'panel in the top wall, lighting means within the cabinet, an elec trostatic charging unit located in and movable endwise of the cabinet and including electrostatic charging wires extending transversely of the cabinet, and guideways located in the cabinet below. the charging unit to receive a plate.

charging wires extending transversely of the.

cabinet, the cabinet having a slot at its front end and communicating guideways located below the charging unit to receive a plate.

3. Electrocopy apparatus comprising a cabinet having top wall, bottom Wall and side Wallshaving a light transmitting panel in one wall thereof, lighting means within the cabinet and means to support an electrophotographic plate against the said light transmitting panel, an electrostatic charging unit located in and movable endwise of the cabinet and including electrostatic charging wires extending transversely of the cabinet, the cabinet having a slot on its front end and communicating guideways located below the charging unit to receive a plate and position it adjacent and parallel to the area of motion of the charging unit.

4. Electrocopy apparatus comprising a lighttight cabinet having top wall, bottom wall and side walls having a transparent panel in one wall thereof to receive an electrophotographic plate for exposure, lighting means Within the cabinet, a support within the cabinet to receive an electrophotographic plate for charging and an electrostatic charging unit including at least one fine conductive strand positioned across and movable over an area across the plate to sensitize the plate by imposing a charge on its surface. 5. Electrocopy apparatus comprising a cabinet having top wall, bottom wall and side Walls having a transparent panel in the one wall thereof, lighting means within the cabinet and means to support an electrophotographic plate against the panel and facing the lighting means for exposure thereto, and an electrostatic charging unit movable endwise of the cabinet and including electrostatic charging wires extending transversely of the cabinet, the cabinet having a slot at its front end and communicating guideways located adjacent the charging unit to receive an electrophotographic plate, said unit being thereby adapted to charge an electrophotographic plate positioned on the guideways and additionally being adapted to apply a charge to a powder image and a superposed transfer sheet positioned on an electrophotographic plate on the guideways for transferring the powder image from the plate to the transfer sheet.

6. Electrocopy apparatus including a cabinet:

- having top wall, bottom wall and side walls having a transparent panel in the one wall thereof, lighting means within the cabinet and means to support'an electrophotographic plate against the panel and facing the lighting means for exposure thereto, an electrostatic charging unit movable endwise of the cabinet and including electrostatic charging wires extending transversely of the cabinet, the cabinet having guideways arranged at opposite sides extending longitudinally adjacent the charging unitand at least one slot at the front end communicating with said guideways, a lighttight supporting frame, an electrophotographic platecomprising a conductive backing and a surface, said supporting frame being slidable into the cabinet adjacent the charging unit for charging the plate and for effecting transfer of a powder image from the plate to a transfer sheet and positionable over said transparent panel for exposing the plate.

7. Electrocopy charging apparatus comprising a cabinet and electrostatic charging means located within the cabinet including a bus bar extending longitudinally of the cabinet adjacent to one side wall, a charging unit including a plate extending transversely of the cabinet and movable on said bus bar, and charging wires mounted on said plate extending endwise thereof transversely of the cabinet and electrically connected to said bus bar.

8. Electrocopy charging and transferring apparatus comprising a cabinet and electrostatic charging means located within the cabinet including a bus bar extending longitudinally of the cabinet adjacent to one side wall, a charging unit including a plate extending transversely of the cabinet and movable on said bus bar, and charging wires mounted on said plate adjacent the bus bar extending endwise of the plate and transversely of the cabinet, the charging wires being connected to said. bus bar and the cabinet having at least one slot in one end wall and communicating guideways in the cabinet adjacent the charging unit to receive a sensitized plate for charging and for transferring a powder image from the plate to a transfer sheet.

9. Electrocopy apparatus for forming a latent electrostatic image on an electrophotographic plate comprising a cabinet having top wall, bottom wall and side walls having a transparent 35 panel arranged in said one wall thereof, lighting means within the cabinet, a plurality of yieldable supports arranged adjacent to said transparent panel, a supporting frame provided with an electrophotographic plate comprising a conductive backing and a photoconductive insulating coating thereon and a removable light shield, the supporting frame being positionable on said yieldable supports over the transparent panel to permit removal of the light shield and movable thereon downwardly toward said transparent panel for bringing the sensitized plate into firm contact with the transparent panel for exposure, and an electrostatic charging unit within and movable endwise of the cabinet and having charging wires extending transversely of the cabinet, the cabinet having at least one slot at one end and communicating guideways adjacent said charging unit to receive the electrophotographic plate for charging and for transferring a powder image from the plate to a transfer sheet.

LEWIS E. \VALKUP. HAROLD E. COPLEY. WALTER A. BECKDAHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 163,359 Chambers et al May 18, 1875 266,564 Ward Oct. 24, 1882 271,826 Flammang Feb. 6, 1883 754,252 Stevens Mar. 8, 1904 776,746 Kinsey Dec. 6, 1904 812,816 Brown Feb. 20, 1906 2,011,675 Cawood Aug. 20, 1935 2,277,013 Carlson Mar. 17, 1942 2,357,809 Carlson Sept. 12, 1944