US3288605A

US3288605A - Electrophotographic printing method

Info

Publication number: US3288605A
Application number: US508659A
Authority: US
Inventors: Macklem F Sutherland
Original assignee: EQUIPMENT DEV CORP
Current assignee: Equipment Dev Co Inc; EQUIPMENT DEV CORP
Priority date: 1965-11-17
Filing date: 1965-11-17
Publication date: 1966-11-29
Anticipated expiration: 1983-11-29

Description

1966 F. s. MACKLEM ELEQTRQPHOTOGRAPHIG PRINTING METHOD Original Filed May 18, 1956 INVENTOR F. SUTHERLAND MflcKLs/w United States Patent 3,288,6u ELECTRQPHOJTGGRAPHHC ERiNTlNG METHQD F Sutherland Maeklem, New Canaan, Comp, assignor to Equipment Development Corp, New Canaan, Conn. Continuation of abandoned application Ser. No. 585,717, May 18, 1956. This application Nov. 19, 1965, Ser. No. 508,659

5 Claims. (Cl. 961) This application is a continuation of my copending application, Ser. No. 585,717, filed May 18, 1956, now abandoned.

My invention relates to photoreproduction apparatus particularly adapted to the employment of electrophotographic paper, film, or the like. This invention incorporates certain improvements over that disclosed in my c0- pending application, Ser. No. 538,619, filed Oct. 5, 1955, now abandoned.

It is an object of the invention to provide improved apparatus of the character indicated and to provide an improved method for utilizing electrophotographic paper, film, or the like.

It is another object to provide improved photoreproduction apparatus of the character indicated, whereby developed copies may be more quickly and easily made.

It is a specific object to meet the above objects with a structure particularly adapted to the efiicient reproduction of translucent masters.

It is another specific object to meet the above objects with an improved method and apparatus which permit full development and fixation of a print while the master and print are held together, that is, before removal of the master from the print,

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a simplified sectional view illustrating important steps in my method and parts of my apparatus; and

FIGS. 2 and 3 are fragmentary diagrams representing alternatives for parts of the method and apparatus illustrated in FIG. 1.

Briefly stated, my invention contemplates photoreproduction apparatus adapted particularly to paper, film, or the like, having a coating which is photosensitive when electrically charged. In the present invention, I am specifically concerned with the improved use of such paper, film, or the like, for reproduction of translucent masters, such as those prepared on tracing paper or vellum in ordinary drafting-shop procedures. My invention features the development of the exposed copy sheet while still held against the master through which exposure is made. In this Way, I best assure retention of all charge developments up to and including the time of development (as by electrostatic dusting techniques), and no separate handling is required of the copy sheet. My machine delivers the fully developed and fixed copy sheet Without ever having separated the copy sheet from the master.

The process of photoreproduction is improved by feeding the photocopy sheet and master into the machine and impressing a charge on opposite sides of both pieces of paper while they are together. After photosensitizing by charging, the two sheets, if desired, may be retained together as mentioned above.

Referring to FIG. 1 of the drawing, my invention is shown in application to a photoreproduction apparatus in which a master sheet or tracing is first brought into register with a copy sheet 11, before introduction to the 328855 Patented Nov. 29, 1966 machine at feed rolls 1213. For convenience, a table 14 is provided to facilitate assembly of the sheets 10-11. Both sheets 10-11 are translucent, and the sheet 11 is of the electrophotographic variety, meaning that it has on one side thereof a coating which is photosensitive when electrically charged. For convenience, throughout the specification and claims I shall refer to such paper, film, or the like 11 merely as paper, it being understood that such reference contemplates any vehicle suitable for the intended purpose and having a coating of the class described,

In the form shown in FIG. 1, the registered master sheet 10 and copy sheet 11 are arranged with the coated side of the copy sheet 11 facing downwardly on the table 14, and the master 10 is oriented for direct (unreversed) printing, that is, with the marked face thereof pressing downwardly against the copy sheet 11. After passing through the feed rolls 1213, the sheets1911 are subjected to an electrostatic charge region, which in the form shown comprises spaced corona-discharge elements 1546 on opposite sides of the sheets 1tl11. The charged sheets are then preferably fed directly to a translucent cylinder 17 and are held against the cylinder 17 by means of a belt 18 running with movement of the cylinder 17 so as to carry the master and copy sheets in the direction indicated by the arrow 19.

The cylinder 17 is mounted for rotation about its axis and may be of glass or translucent plastic, but for convenience throughout this specification, will be referred to as a glass cylinder, even though other materials will be understood to be contemplated by reference to the cylinder 17 as a glass cylinder.

Within the cylinder 17 is a fixed light source 20 which is preferably directional and limited to essentially an elongated area substantially coextensive with the width of the copy sheet and located at essentially one angular location about the axis of the cylinder 17. The light source 20 may be a fluorescent lamp, and shield 21 provides the desired directionality.

While in the form shown the exposed charged master and copy sheets 10-11 are still held against each other and are advanced with movement of the cylinder 17, I provide means for developing the charge image which results on exposure. In the form shown, an electrostatic dusting brush 22 is employed at a second fixed angular location about the axis of the cylinder 17. The brush 22 may be of cylindrical configuration and elongated in substantial conformity with elongation of light source 20. Brush 22 is shown to rotate continuously in a trough 23 having an aperture 24 adjacent the exposed coated surface of the copy sheet 11. Dusting material 25 is shown filling the trough 23, and an access door 26 facilitates replenishment. Brush 22 is preferably driven at a velocity to achieve a small relative surface speed of the brush over the exposed coated surface of copy paper 11 as it passes the brush aperture 24.

At a third fixed angular location about the axis of the cylinder 17, I show means 27 for fixing the developed image on paper 11. This operation may be performed by application of heat to the coated surface of paper 11 at an elongated aperture substantially coextensive with the exposed and developed width of the copy sheet 11. The heating means is shown to include an electrical heating element 28 and a blower 29. After fixing, the master and copy sheets are tangentially peeled off the roll 17 at 3%. and feed-out rolls 31-32 discharge the original and the finished copy at an upper table 33, at which time the copy may be removed from the master,

The arrangements of FIGS. 2 and 3 are similar to FIG. 1 in that there is shown a feeding of a master and photocopy paper to a charging chamber wherein an electrical potential is impressed on opposite sides of the master and photocopy paper.

The arrangement of FIG. 2 represents a slight modification'wherein but a single corona-discharge element 15 is employed, preferably adjacent the coated surface of the copy sheet 11. In order to establish a charge reference for the means 15, I show a single plate 35 adjacent the upper surface of the master 10, and this plate may be referenced to ground potential, as suggested at 36. If desired, the translucent cylinder 17' may be of the electrically conductive variety, as of electrically conducting glass, and a brush element 37 assures maintenance of the same ground potential both on the plate 35 and on the cylinder 17'.

In the arrangement shown in FIG. 3, the translucent cylinder 17 is again of the electrically conductive variety, and reference of the potential thereof to ground potential is suggested at 38. Electrostatic charging of the sheets is accomplished at a corona-discharge element 39 fixed between the pulleys 4041 for the belt 18. Auxiliary pulleys 42-4344 are shown for routing the belt 18 around the charge element 39, so that the desired charge development may be effected directly on the outer face of the copy sheet and with respect to the potential (ground) of the cylinder 17'. It will be noted that the charge element 39 is so located as to complete its charging function prior to exposure of the copy sheet to light from source 20.

It will be seen that I have described a relatively simple photoreproduction apparatus, particularly applicable to the reproduction of translucent masters, such as engineering drawings on tracing paper, vellum, or the like. I have found that highly satisfactory reproductions can be made even though the coating of the copy sheet faces away from the master sheet, and the fact that in accordance with my preferred form I perform development and fixing of the charged image prior to separating the master from the copy sheet assures maximum retention of electrostatic charge images, so that more reliable results can be accomplished than by the conventional method of facing the coating against the master and separating the copy sheet from the master for development and fixing. Also, my method and apparatus permit direct reproduction without reversal of the image from the master.

While I have described the invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as defined in the claims which follow.

I claim:

1. The photo-reproduction method employing a sheet of translucent paper having a photoconductive insulative coating on one side thereof that is photoelectricallyresponsive when subjected to an electrical charge, which comprises positioning a positive translucent master on the uncoated side of said sheet, impressing an electrical potential on opposite sides of said sheet and master while in contact with each other, directing illumination through said master and sheet to the photoconductive side thereof, thereby producing an electrical charge pattern corresponding to the copy on said master, and developing said coating while held in contact with said master by applying solid developer particles to said photoconductive side, the particles adhering to the side in accordance with said charge pattern.

2. The photo-reproduction method employing a sheet Of translucent paper having a photoconductive insulative coating on one side thereof that is photoelectricallyresponsive when subjected to an electrical charge, which comprises positioning a positive translucent master to the uncoated side of said sheet with the copy on said master lying adjacent said uncoated side, impressing an electrical potential on opposite sides of said sheet and master while in contact with each other, directing illumination through said master and sheet to the photoconductive side thereof, thereby producing an electrical charge pattern corresponding to the copy on said master, electrostatically developing the resulting charge pattern on the exposed coated surface while said sheet is held in contact with said master by applying solid developer particles to said photoconductive side, and heating said developer particles to fix the electrostatic image while said sheet is held in contact with said master.

3. The photo-reproduction method employing a sheet of translucent paper having a photoconductive insulative coating on one side thereof that is photoelectrical1y-re sponsive when subjected to an electrical charge, which comprises positioning a positive translucent master on the uncoated side of said sheet, impressing an electrical potential on opposite sides of said master and sheet while in contact with each other, directing illumination through said master to the photoconductive side of said sheet, thereby producing an electrical charge pattern corresponding to the copy on said master, and developing said coating by applying developer to said photoconductive side.

4. The photo-reproduction method employing a sheet of translucent paper having a photoconductive insulative coating on one side thereof that is photoelectricallyresponsive when subjected to an electrical charge, which comprises positioning a positive translucent master on said sheet, impressing an electrical potential on opposite sides of said master and sheet while in contact with each other, directing illumination through said master to the photoconductive side of said sheet, thereby producing an electrical charge pattern corresponding to the copy on said master, and developing said coating by applying developer to said photoconductive side.

5. The photo-reproducing method employing a sheet of translucent paper having a photoconductive insulative coating on one side thereof that is photoelectrically-responsive when subjected to an electrical charge which comprises:

positioning a positive translucent master on the uncoated side of said sheet;

impressing an electrical potential on opposite sides of said master and sheet while in contact with each other to charge substantially the entire area of said photoconductive coating of said sheet;

and, directing illumination through said master and sheet to the photoconductive side thereof, thereby producing an electrical charge pattern corresponding to the copy on said master;

and developing said coating by applying solid developer particles to said photoconductive side, the particles adhering to the side in accordance with said charge pattern;

and thereafter fixing said particles to said sheet.

No references cited.

NORMAN G. TORCHIN, Primary Examiner. C. E. VAN HORN, Assistant Examiner.

Claims

4. THE PHOTO-REPRODUCTION METHOD EMPLOYING A SHEET OF TRANSLUCENT PAPER HAVING A PHTOCONDUCTIVE INSULATIVE COATING ON ONE SIDE THEREOF THAT IS PHOTOELECTRICALLYRESPONSIVE WHEN SUBJECTED TO AN ELECTRICAL CHARGE, WHICH COMPRISES POSITIONING A POSITIVE TRANSLUCENT MASTER ON SAID SHEET, IMPRESSING AN ELECTRICAL POTENTIAL ON OPPOSITE SIDES OF SAID MASTER AND SHEET WHILE IN CONTACT WITH EACH OTHER, DIRECTING ILLUMINATION THROUGH SAID MASTER TO THE PHOTOCONDUCTIVE SIDE OF SAID SHEET, THEREBY PRODUCING AN ELECTRICAL CHARGE PATTERN CORRESPONDING TO THE COPY ON SAID MASTER, AND DEVELOPING SAID COATING BY APPLYING DEVELOPER TO SAID PHOTOCONDUCTIVE SIDE.