US2705675A - Plate charging circuit for electrophotography - Google Patents

Description

pm] 5, 1955 w. a BIXBY 2,705,675

PLATE CHARGING CIRCUIT FOR ELECTROPHOTOGRAPHY Filed Jan. 12, 1950 2 Sheets-Sheet l FIGURE 4 TREE 3 8 LEAF J V FIGURE 5 INVENTOR. Wil liclrn E. Bixby April 5, 1955 -w. E. BIXBY 2,705,675

PLATE'CHARGING CIRCUIT FOR ELECTROPHOTOCRAPHY Filed Jan. 12, 1950 2 Sheets-Sheet 2 ,25 25 53 r 5/ zs vfl IF k FIGURE 2 FIGURE 3 INVENTOR. Wil liom E. Blxby United States Patent PLATE CHARGING CIRCUIT FOR ELECTROPHOTOGRAPHY William E. Bixby, Columbus, Ohio, assignor, by mesne assignments, to The Battelle Development Corporation, Columbus, Ohio, a corporation of Delaware Application January 12, 1950, Serial No. 138,252

1 Claim. (Cl. 95--1.9)

This invention relates to a novel and educational toy and, in particular, to an interesting and instructive electrophotographic toy kit which will be of interest to the amateur experimenter and will provide a fascinating and educational toy for children. Specifically, this invention relates to a novel electrophotographic toy apparatus and to its associated elements.

Electrophotography is a dry, electrical method of photography. Plates having a coating of a photoconductive material are used in the process and possess the advantage of being capable of repeated use. The sensitizing process is of an electrical nature and the development of images is accomplished by dry powder mixtures. Images produced in accordance with the method are made permanent by the application of heat.

The device of the present invention provides a combination of elements for carrying out the various steps of the electrophotographic process in an entertaining manner, while at the same time providing educational ad vantages and features.

It is an object of this invention to provide an electrophotographic toy device.

It 1s another object of this invention to provide anelectrophotographic toy kit having educational merit as well as entertainment value.

It is a further object of this invention to provide a toy which can be used to reproduce images or print by a dry electrical process.

It is a still further object of this invention to provide a new and novel electrical power circuit for a toy electrophotographic apparatus.

Other objects and advantages of this invention will become more apparent from the following detailed description thereof, especially when read in view of the accompanying drawings wherein,-

Figure l is a top view of the toy kit with the hinged cover removed,

Figure 2 is a vertical section view along the line A--A of Figure 1 with the hinged cover on, showing the arrangement of elements making up a toy kit,

Figure 3 is a diagram of the power supply unit and cooperating elements for the device,

Figure 4 illustrates a type of developer tray used with the kit,

Figure 5 represents a few of the various designs and copy material which may be provided with the toy kit and illustrates the potential educational value of the device.

Referring now to the particular embodiment illustrated by the drawings, is the toy kit housing having hinged cover 11 and provided witli"four main compartments 13, 14, and 16. The compartment 13 provides for storage of the various powders and transfer papers used in the operation of the device. Compartment 14 is reserved for the power supply elements, while 15 is the sensitizing compartment which is light shielded and which includes a slit along its lower face through which an electrophotographic plate is inserted for sensitization under the sensitizing wire 18. Compartment 16 encloses an exposing and fixing source 19 and, when the device is not being used, serves as storage space for trays 20-20. A transparent plate glass or plastic copy or plate holder 22 is provided over this compartment. The fixing and exposing element is an ordinary electric light bulb. (These elements are shown in Figures 1 and 2.)

Tray 20 is used in either the developing or cleaning process, or both. When not in use the tray may be stored in compartment 16, as shown in Figure 2. Lips 25-25 are provided so as to fit the tray 20 into storage racks formed by ledges 2626 along either side of compartment 16. Stops 3030 are provided in the bottom of each tray 20 and these serve to position and maintain an electrophotographic plate in place during the cleaning and developing processes.

The sensitizing elements of the toy kit are shown in Figure 3 with the power supply being represented by electrical symbols while the mechanical elements are shown in isometric. The power supply utilizes a spark coil 31 to produce the high voltages required to effect corona discharge. The energy source is composed of three size D (or flashlight size) dry cells 32. A condenser 33 completes the list of electrical elements used. Mechanical elements in the sensitizing portion of the kit include insulator posts 3535, corona discharge wire 18, and serrated metal tracks 3838. Condenser 33 should be connected in shunt across tracks 3838. Also illustrated in the drawing are xerographic plate 40 comprising a photoconductive insulating layer on a conductive backing, and a plate holder 39 made of insulating material, which are represented so as to illustrate the relative positions of the elements during the sensitizing (or charging) process. When not in use the plate 40 may conveniently be stored inside the housing 10, for example immediately below the hinged cover 11.

Other elements represented in the various figures include containers 5050 which are filled with developer material 51 or cleaner material 52, as will be more fully discussed later. 53 represents a supply of paper sheets which serve as transfer sheets. A recessed electric plug 60 is provided in the wall of the kit and the necessary electric extension cord, although not shown, is also provided with the kit. Energy led in through plug 60 is used only for lighting the exposure lamp 19.

The designs shown in Figure 5 illustrate only a few of the numerous subjects which could be included among the toy kit patterns. As indicated the patterns provided may be suitable for familiarizing youthful operators with a variety of educational subjects, including, as illustrated, famous men of history, magic squares, geography, famous ships, and plant and animal identification. There are innumerable other possibilities for designs of an educational nature and all of them, when used in connection with the electrophotographic toy kit of this invention, as hereinafter more fully described, will provide hours of entertainment and relaxation.

The operation of the toy can be best described and understood in connection with all the drawings and figures. Preparatory to using the toy the trays 2020 should be removed from the shelves in section 16 and containers 5050 filled with developer material 51 and cleaner material 52 should also be set out so as to be conveniently at hand when needed. The extension cord should also be connected, first at the recessed electric plug and then to a v. power source. Preferably an On-Off switch is provided in the extension line. The exposure lamp need not be switched on until needed for the exposure step.

Actual operation of the toy begins with the insertion of the electrophotographic plate 40 through the slit in section 15. The plate 40 contacts the serrated track or runway 38-38 as indicated in Figure 3. Plate holder 39 should be used to hold and direct the plate 40 during the charging operation. As the plate is inserted further and further through the slit its travel across the serrated track 38-38 is characterized by a vibratory or jumping action wherein the plate rapidly opens and closes the power supply circuit by alternately contacting and breaking contact with the metal runways 33-38. The width of the slit in the face of the toy is adjusted so as to make it impossible to contact the discharge wire 18 with the electrophotographic plate 40. Referring again to Figure 3 it is seen that the opening and closing of the circuit through the metal runways 38--38 produces a pulsating current through the primary coil 45 of spark coil 31, whereupon a voltage is induced in secondary coil 44. By reason of the slow making-quick breaking of the circuit (which action is brought about by the on-otf switching effect of the plate on the serrated runway and by the condenser 33) the voltage induced in the secondary is of considerable magnitude and effectively unidirectional. This secondary voltage is applied, as indicated, directly across the plate 40 and the corona discharge wire 18. The corona spray so produced deposits an electric charge uniformly on the surface of plate 40. Three or four passes of the plate across the serrated strips are usually sufiicient to provide an adequate, and substantially uniform charge density on the plate 40.

The electrophotographic plate 40 charged in the manner just described is next removed from the plate holder 39 and placed, charged side down, over the glass 22, and exposure lamp 19 is turned on for a suitable period of timeten seconds ordinarily being sufiicient. It will be understood, of course, that during this exposure step a suitable pattern or image to be reproduced is positioned between the glass 22 and the charged electrophotographic plate 40. Numerous samples of these patterns are illustrated in Figure 5, it being understood that the patterns or images to be reproduced are printed, drawn, or otherwise permanently aflixed to a transparent material, so as to permit light to pass through the non-image areas. Thus, in accordance with known electrophotographic principles, the electrostatic charges on the non-image areas are released by reason of the areas becoming electrically conductive due to the light striking them. An electrostatic image of the pattern to be reproduced is thus prepared on the surface of the electrophotographic plate 40.

The plate bearing such electrostatic image is next placed in the bottom of developer tray 20 with the coated side up. Developer powder 51 from container 50 is poured into the tray 20 which is then rocked back and forth in such a way as to cause the particles of developer powder to pass across the electrostatic-image-bearing plate. It will be found that these particles will be attracted and held by the electrostatic electricity on the coating so as to form a powder image of the design on the transparent sheet through which the exposure was made.

Once developed, the powder image is transferred to a paper surface (a pad of suitable paper sheets is supplied with the toy kit) in the following manner: The paper to which the image is to be transferred is placed over the powder image on the plate and the assembly inserted into the slot in compartment 15 as in the sensitizing process, the paper being next to the sensitizing wire. When the assembly of paper, image, and plate has been inserted and withdrawn from the slot several times, it will be found that the image has transferred to the paper sheet. The paper is peeled from the plate, and the transferred image on the paper is fused to the paper by lighting the exposure light 19 and placing the paper, image side up, over the exposure bulb 19 whereupon the heat from the light source 19 will fuse the powder image to the paper sheet. Any powder particles which still cling to the plate may be removed by placing the plate in a cleaning tray 21 (which may be the same tray, 20, which was used for developing the image, but which is preferably a separate tray) pouring some of the cleaner material from the storage bottle into the tray 21 and passing the cleaner back and forth across the plate as was done with the developer powder in the developing process. It will be understood that both the developer powder and the cleaner material are poured from the tray 20 or 21 into the proper storage bottle for storage until the next operation.

While the apparatus is operable in a normally lighted room, the charged plate should not be exposed to intense illumination, i. e., to a strong light at short distance, or otherwise the plate will be discharged prematurely.

It will be appreciated that the particular elements of the toy kit herein described are subject to various design revisions without passing beyond the scope of this invention.

What is claimed is:

An electrophotographic apparatus comprising an electrophotographic plate, a housing member having a slit therein for admitting said electrophotographic plate, a corona discharge element within said housing and located with respect to said slit so as to spray electric charges on an electrophotographic plate inserted through said slit, a power supply comprising a spark coil having a primary coil and a secondary coil, a voltage source in series with the primary coil, a condenser in series with said voltage source and said primary coil, a pair of serrated contact elements connected one to each side of said condenser, one of said contact elements being also connected to one side of the secondary coil while the other side of said secondary coil is connected to the corona discharge element. said serrated contact elements being disposed within the housing and extending rearwardly from the slit in said housing and spaced laterally to support an electrophotographic plate inserted through said slit, whereby an electrophotographic plate inserted through said slit and moving along said serrated contacts alternately makes and breaks electrical contact thereby opening and closing the power supply circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,097,131 Kitsee May 19, 1914 1,279,823 Balsillie Sept. 24, 1918 1,835,416 Mathis Dec. 8, 1931 2,000,868 Stowell May 7, 1935 2,137,375 Alexander Nov. 22, 1938 2,221,776 Carlson Nov. 19, 1940 2,593,978 Cajumi Apr. 22, 1952 FOREIGN PATENTS 484,142 France Sept. 7, 1917 444,255 France Nov. 28, 1919 776,049 France Jan. 15, 1935 815,944 France July 26, v 1937 OTHER REFERENCES Xerography, article in American Photography magazine, for January 1949, page 41.

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