US3606309A - Sheet separating device for photocopying machine - Google Patents

Abstract

A SHEET SEPARATING DEVICE FOR AN ELECTROSTATIC CONTACT TYPE COPYING MACHINE. THE SEPARATING DEVICE IS FORMED OF A THIN WEB OF TRANSPARENT MATERIAL WHICH HAS ON THE EXIT SIDE A SHEET DIVERTER FORMED OF A PAIR OF DIVERGING SECTIONS EACH OF WHICH SECTIONS FLARE OUTWARDLY.

Description

Sept. 20, 1971 E. J. PETRICK EIAL 3,606,309

SHEET SEPARATING DEVICE FOR PHOTOCOPYING MACHINE Filed May 1, 1970 sum/4R0 1 PETE/CK AAYMOA/D SCf/M/OL //v ATTUENEY United States Patent O 3,606,309 SHEET SEPARATIN G DEVICE FOR PHOTOCOPYING MACHINE Edward J. Petrick, Euclid, and Raymond J. Schmidlin,

Lyndhurst, Ohio, assignors to Addressograph-Multigraph Corporation, Cleveland, Ohio Filed May 1, 1970, Ser. No. 33,674 Int. Cl. B65h 29/64 US. Cl. 271-64 9 Claims ABSTRACT OF THE DISCLOSURE A sheet separating device for an electrostatic contact type copying machine. The separating device is formed of a thin web of transparent material which has on the exit side a sheet diverter formed of a pair of diverging sections each of which sections flare outwardly.

I BACKGROUND OF THE INVENTION This invention relates generally to separating devices, and more particularly to devices for separating an original and a copy sheet after exposure of the original onto the copy sheet in a photocopying machine. The invention is particularly applicable to and useful in photocopying machines which utilize the contact exposure process of reproducing images from the original sheet onto a copy sheet. In such a device, the original and copy sheets are introduced into the machine and are transported past an exposure zone or station in face-to-face contact at which zone the copy sheet is exposed to produce a latent image of the material on the original. After leaving the exposure zone, the original and the copy sheets must be separated so that the copy sheet can be further processed to develop the latent image thereon, and the original ejected from the machine.

There have been several prior art proposals for separating the original and copy sheets. For example, it has been proposed that air be blown on the edges of the two sheets to cause a separation thereof. This has not proved entirely satisfactory, since the blowing of air does not assure a separation. Also, it has been proposed to utilize a plurality of longitudinally extending thin transparent filaments, which filaments extend from the entrance side to the exit side of the exposure zone and are interposed between the two sheets. The filaments are arranged so that alternate filaments are on divergent planes on the exit side so as to effect a separation of the sheets. This scheme also has several drawbacks. First, the use of a multiplicity of elements provides a configuration wherein the edges of either the original document or the copy sheet can become caught on the wrong side thereof, thus not only failing to provide document separation, but also actually damaging the documents. This is especially true when documents of different widths are to be copied by the machine since for certain widths one of the filaments will be located close to the edge of the documents making it easy for the edge to slip on the wrong side thereof.

Another of the drawbacks to these filaments is that, in order to obtain suflicient strength, the filaments have -had to have substantial thickness. This thickness is usually great enough to cause document separation of suflicient magnitude that undercutting of the light occurs, resulting in streaking or lining of the copy at the location of the filaments when the copy sheet is exposed. Even controlling the shape and configuration of these filaments has not completely eliminated the problem of lining or streaking of the copy sheet.

SUMMARY OF THE INVENTION According to the present invention, a sheet separator for separating a copy sheet from an original sheet in a photocopying machine is provided which includes a longitudinally extending web of transparent material. The web of material has a central portion at the exposure station and opposite end positions at the entrance and exit sides of the exposure station. The transparent material, especially at the central portion, is relatively thin, preferably less than .001" thick, and has a width sufficient to prevent breakage when it is maintained under tension. The portion of the web on the exit side has a sheet diverter and formed of a pair of sections which extend from the central portion on diverging planes, and each diverging section also flares laterally and longitudinal- 1y, i.e., increase in width along the length thereof, to provide effective separation.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view somewhat diagrammatic showing the sheet separating device of this invention as used in the mechanism of an electrostatic copying machine;

FIG. 2 is a sectional view taken substantially along the plane designated by the line 2-2 of FIG. 1; and

FIG. 3 is a plan view of the sheet separating device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, and for the present to FIGS. 1 and 2, there is illustrated, somewhat diagrammatically, the exposure section of a contact type of photocopying machine together with the entrance and exit sections on opposite sides thereof.

The illustrated portion of the photocopying machine includes an exposure station designated generally as 10, which has a light source 12 surrounded by a reflector 14. The reflector 14 has a transversely extending opening 16 defined by a retainer plate 18 secured to the reflector and disposed to provide a uniform opening for the emission of light from the light source 12.

The retainer plate 18 constitutes the support member for one of the sheets which travel past the exposure station 10. Disposed on the opposite side of the retainer plate 18 is a longitudinally extending generally U-shaped support bar 20 which has secured thereto by means of screws 21 a sheet of relatively resilient material 22 having a low coefficient of sliding friction such as Mylar or a similar type plastic. The plastic material 22 serves as a pressure member bearing against the retainer plate 18 and will urge the sheets to be copied into engagement with each other and against the retainer plate as they pass the exposure station.

On the entrance side of the exposure station ,10 are disposed a pair of entry rolls 23 and 24 which are journalled for rotation in the direction indicated by the arrows and on the exit side of the exposure station 10 are a pair of exit rolls 25 and 26 journalled for rotation in the direction shown by the arrows. The rolls 23', 24, 25 and 26 are adapted to engage and transport a pair of superimposed flat sheets designated by the arrowed lines 28 and 30 (FIG. 2) to and through the exposure station 10. The sheet 28 represents an electrostatic copy sheet having 2. treated surface which is disposed to be in contact with the face of sheet 30, which represents an original document to be copied. The entry rolls 23 and 24 engage the sheets 28 and 30 and drive them to and past exposure station 10. When the sheets 28 and 30 emerge from the exposure station 10, they are engaged by the rolls 25 and 26 so that the rolls 23, 24,

25 and 26 act in conjunction with each other to provide a positive feed mechanism for the original and copy sheets.

When the sheets 28 and 30 have been exposed, it is necessary that the copy sheet 28 be further processed to develop the latent image, and the original sheet 30 must be returned. Thus, the sheets require separation. In order to effect the separation of these sheets, a sheet separating structure is provided. The sheet separating structure includes a web of clear transparent plastic film designated generally as 32. This web, which can best be seen in plan view in FIG. 3, includes a longitudinally extending central portion 34 which terminates on one end thereof with an entrance bar engaging portion 36 having a plurality of apertures 38 disposed to engage with screws 40 on entrance bar 42.

The opposite end portion of the plastic film 32 on the exit side is formed with a sheet diverter 43. The sheet diverter 43 includes a return end piece of the plastic film- 32 which is heat-sealed as shown at 44 to form a loop 46. The loop 46 is disposed to engage an exit bar 48 so that the diverter 43 has a pair of diverging sections 50 and 52 extending on diverging planes.

As can best be seen in FIG. 3, the sections 50 and 52 each flare rapidly outwardly from the narrow central portion 34 to a relatively wide end 54 which preferably extends substantially the entire width of the widest copy sheet to be used in the machine.

The plastic film 32 is disposed in the copy machine with the central portion 34 thereof extending centrally of the rollers 23, 24, 25 and 26, and centrally of the exposure station 10. The rollers each have central relief portions (unnumbered) so that they will not drivingly engage the plastic web. The plastic film 32 is formed of a transparent material which can be maintained taut to prevent any wrinkling thereof and the surfaces of which have a relatively low coefficient of sliding friction to allow the original and copy sheets to slide therealong without catching or without damaging the sheets. It is preferred that the thickness of the central portion 34, especially where it is adjacent the opening 16, be less than .001" thick. If the thickness of the web material is greater than .001", the separation of the sheets being copied is sufiiciently great so that there is a distortion of the image. Further, with separation of more than .001" there is a tendency toward the phenomenon of undercutting of the light along the edges of the web, which phenomenon results in the appearance of lines on the finished copy at the locations of these edges. However, with a thickness of less than .001", good image reproduction is obtained and the phenomenon of undercutting by the light is not present.

One suitable material for the plastic web is clear Mylar plastic approximately .00075" thick. With Mylar plastic of this thickness, a very satisfactory width of the central portion 34 is A". This width provides suflicient strength to maintain the plastic under tension without the plastic breaking or tearing. It is understood, however, that any width of the central portion can be utilized provided it is sufliciently wide to provide the necessary strength to resist breaking or tearing.

With respect to the maximum width of the plastic film, this is dictated merely by the nature of the equipment being utilized. In the disclosed embodiment, rollers are utilized to feed two sheets past the exposure station 10. Hence the rollers 23, 24, 25 and 26 must contact the sheets in order to drivingly engage them, and thus the width of the plastic, at least in the vicinity of the rollers must be narrower than the sheets of material which are to be utilized in the machine in order that the rollers can grip and drive them. Otherwise there is no maximum width.

In the operation of the sheet separating device, the sheets 28 and 30 are fed into the rolls 23 and 24 from opposite sides of the entrance bar 42, as shown in FIG. 2. The rolls 23 and 24 drive the sheets to the exposure station 10, and the pressure member 22 presses the sheets 28 and 30 firmly together and firmly against the retainer plate 18 as they pass the exposure station. The light from the light source 12 passes through the opening 16 and exposes the copy sheet 28 to the image on the original sheet 30. From the exposure station 10 the rollers 25 and 26 engage the superimposed sheets 28 and 30 and continue to drive them toward the sheet diverter 43.

While the sheets 28 and 30 have been passing between the rollers 23, 24, 25 and 26, and past the exposure station 10, the central portion 34 of the plastic web 32 has been interposed between the sheets centrally thereof while the remainder of the sheets 28 and 30 have been in faceto-face contact. As the sheets reach the sheet diverter 43, the diverging sections 50, 52 of the loop configuration acts as a diverter for the sheets 28 and 30 as shown in FIG. 2. This diverting action of the sections 50 and 52 will gradually divert the sheet 28 on an angularly upward path, and the sheet 30 on an angular downward path. Also, the outwardly flaring configuration of the sections 50 and 52 progressively engages a greater and greater width of the sheets 28 and 30 so that at the end of the exit bar 48 essentially the entire width of both of the sheets are engaged by the plastic web 30, thus having effected complete separation of the sheets.

Therefore, it can be seen that, in essence, the separation of the sheets as they emerge from the exit rolls 25 and 26 is the result of a dual type of action by the sections 50 and 52 on the sheets 28 and 30. As the sheets progress, they are progressively engaged by a wider and wider segment of the plastic sheet 32 causing separation, and also the diverging sections 50 and 52 guide the sheets to divergent paths, resulting in what could be characterized as a peeling action, essentially peeling the two sheets from each other.

In order to achieve this type of peeling action, the sections 50 and 52 of the sheet diverting section 43 flare outwardly as shown in FIG. 3 with these outwardly flaring portions each subtending an angle with respect to a line normal to the longitudinal axis of the machine designated as a in FIG. 3. It is desirable that angle a be as large as possible. However, in most machines, there are serious space limitations so that from a practical point of view, it is difficult to obtain an optimum large angle. However, in order to provide an effective peeling action, as above described, it is necessary that this angle a be at least 7 degrees, and preferably it should be greater than 10 degrees. An angle of 11 degrees has proved to be satisfactory. If this angle is less than about 7 degrees, there is a rather marked tendency for the edges of the sheets 28 and 30 to engage the edges of the sections 50 and 52, causing damage and, in fact, in some cases jamming the sheets in the machine. This tendency toward engagement of the edges is reduced markedly above 7 degrees and is virtually eliminated above an angle of 10 degrees.

What is claimed is: 1. In an apparatus having a station at which two sheets are in superimposed relationship with each other; the combination of; drive means, and sheet separating means, said drive means being disposed to drive said sheets past said station from an entrance side thereof to an exit side thereof;

said sheet separating means including a web of transparent material having a central portion, means mounting said web of material with one end portion thereof at the entrance side of the station and the opposite end portion at the exit side of the station with the central portion disposed at the station, said Web of material having a sheet diverter at the end portion thereof on the exit side of the station, said sheet diverter including a pair of sections lying on planes diverging from the plane of said central portion and disposed to guide the two sheets on diverging paths to separate the sheets after they emerge from the station.

2. The invention as defined in claim 1 further characterized by said drive means including drive rolls for drivingly engaging said sheets;

said sheet separating means extending beyond said drive rolls, and said drive rolls included recessed portions to accommodate said central portion of the sheet separating means without driving engagement therewith.

3. The invention as defined in claim 1 wherein at least the central portion of the web is no greater than approximately .001" thick.

4. The invention as defined in claim 1 wherein said diverging sections each flare outwardly from the central portion from a narrow to a wide width.

-5. The invention as defined in claim 4.wherein the edges of said outwardly flaring sections subtend an angle of at least 7 deg. with respect to a line normal to the center line of the web.

6. The invention as defined in claim 4 wherein said outwardly flaring sections subtend an angle of at least 10 deg. with respect to a line normal to the center line of the web.

7. The invention as defined in claim 1 wherein said pair of diverging sections constitute opposite portions of a loop formed at the' end portion of the web of material.

8. The invention as defined in claim 7 wherein said loop engages an exit bar, which bar maintains the web under tension.

9. The invention as defined in claim 1 wherein said central portion of the web of material is substantially narrower than the narrowest sheet to be copied.

References Cited v UNITED STATES PATENTS 113,769 4/1871 Hoe Z7164X 853,480 5/ 1907 Smith 2715l 3,386,730 6/1968 Hyosaka 271--64 JOSEPH WEGBREIT, Primary Examiner B. H. STONER, Ira, Assistant Examiner U.S. c1. X.R. 271-51, Dig. 2

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