WO1990010349A1

WO1990010349A1 - Security facsimile transmission system

Info

Publication number: WO1990010349A1
Application number: PCT/US1990/000550
Authority: WO
Inventors: Jeanette C. Tan; Jerry R. Iggulden; Donald A. Streck
Original assignee: Tan Jeanette C; Iggulden Jerry R; Streck Donald A
Priority date: 1989-02-21
Filing date: 1990-01-25
Publication date: 1990-09-07
Also published as: AU5084890A

Abstract

A security method and apparatus for use in providing an 'invisible envelope' for facsimile transmission thereby avoiding the casual reading of documents by persons interposed between the receiver of the transmission and the ultimate designated recipient thereof. Each page of the document is pattern divided into two portions (10', 10'') which are individually unreadable in an easy and straightforward manner. The two portions are sent in sequence (i.e. at different times) and then the original document (10) is reconstituted at the receiving end by the designated recipient employing a transparency (10''') overlay process with the two portions. The patterning at the transmitting end may be accomplished by an optical filtering process or may be computer generated as by modifying word processing software or by a separate program manipulating a pre-input document to produce the two portions for printing and transmission. The HideaFAX process of this invention is applicable to conventional FAX machines without modification. It can also be built into a conventional FAX machine and can be easily added to the software of PC-fax or KeyFAX systems for inclusion therein. A preferred patterning device and a preferred transparency overlay are shown.

Description

SECURITY FACSIMILE TRANSMISSION SYSTEM Background of the Invention:

This invention relates to facsimile transmission systems and methods and, more particularly, to a method and associated apparatus for sending a document between a sender and a receiver by facsimile in a manner which prevents unauthorized casual reading of the document at the receiving end.

The sending of documents by facsimile is an ever increasing phenomonon. On the positive side, facsimile transmission is fast, accurate, and inexpensive. On the negative side, it is like sending a postcard; that is, everyone in the chain of delivery can read the contents of the transmission. This is particularly annoying where the transmitted document contains personal or priviliged information.

Wherefore, it is the object of this application to provide a method and associated apparatus for sending a document between a sender and a receiver by facsimile in a manner which prevents unauthorized casual reading of the document at the receiving end.

escrj-pt^on of_. frhe Prawjngs :

Figure 1 is a simplified drawing of a test document to be transmitted according to the method of the present invention.

Figure 2 is a drawing of one "A" pattern that can be employed in the method of the present invention.

Figure 3 is a drawing of one "B" pattern that can be employed in the method of the present invention in combination with the "A" pattern of Figure 2.

Figure 4 is a block diagram of the basic steps of the method of the present invention when implemented in its simplest embodiment. Figure 5 is a drawing showing the pixel portions of the document of Figure 1 transmitted at time one after being filtered by the "A" pattern of Figure 2.

Figure 6 is a drawing showing the pixel portions of the document of Figure 1 transmitted at time two after being filtered by the "B" pattern of Figure 3. Figure 7 is a drawing showing how the pixel portions of Figures 5 and 6 which are time shifted by transmission at two different times are reconstructed to form a facsimile of the document of Figure 1.

Figure 8 is a drawing of a document transport envelope according to the present invention an incorporating the "A" and "B" pattern filters of Figures 2 and 3 therein.

Figure 9 is a combined functional block diagram and logic flowchart of the apparatus and logic required to implement the present invention in the hardware of various facsimile transmission devices.

Figure 10 is a drawing of a composite copy package which can be employed with the present invention to improve registration in the reconstruction process.

Figure 11 is a simplified drawing depicting the basic pattern construction technique upon which the invention of this continuation-in-part application is based.

Figure 12 is a simplified top view of the frame and pattern portion of the patterning device disclosed herein.

Figure 13 is a cross section of the frame and pattern portion of Figure 12 in the plane XVIII-XVIII.

Figure 14 is a simplified top view of the sliding member of the patterning device disclosed herein.

Figure 15 is a side view of the bottom end of the sliding member of Figure 14. Figure 16 is a simplified bottom view of the sliding member of Figure 14 showing the transparent carrier sheet hingedly attached thereto.

Figure 17 is a simplified drawing of the patterning device disclosed herein in an assembled state. Figure 18 is an enlarged partial top view cutaway through the detent and limit peg of the upper crossbar of the frame of the assembled patterning device of Figure 17.

Figure 19 is a greatly enlarged elevation view of the detent and limit peg looking longitudinally down the double keyhole slot in the sliding member of Figures 14 and 16. Figures 20 and 21 are simplified drawings showing additional steps to the method added by use of the preferred transparency.

Figure 22 is a simplified top view of a photocopyable transparency according to a preferred embodiment of this application.

Figures 23-25 are simplified drawings showing the manner in which the edges of the photocopyable transparency of Figure 22 are broken off along pre-established break lines formed therein to expose adhesive strips which are used to adhesively attach the transparency to the partial document with which it is in registration.

Figure 26 is a simplified top view of a photocopyable transparency employing alternate embodiments of adhesive attachments . Figures 27 and 28 are simplified drawings showing the manner in which the protective covering of adhesive strips employed in the embodiments of Figure 26 is removed to expose the adhesive which is used to adhesively attach the transparency to the partial document with which it is in registration.

Figure 29 is a simplified drawing showing a preferred addition to the embodiments of Figures 26-28.

esgrj on Pf fre Preferred Embodiment: The present invention is based on the proposition of dividing the pixels of each page of a document into two groups according to at least two intermeshed patterns (one being the reverse of the other) ; transmitting, receiving, and printing the two groups at different times to create two individually unreadable documents; and then recombining the two documents under secure conditions to recreate a facsimile of the original document. As will now be described in detail, this can be accomplished according to the present invention with existing equipment requiring no modification to either the transmitting or receiving facsimile hardware. It can also be built into the transmitting hardware for receipt and reconstruction on the receiving end with standard hardware. Figure 1 depicts a document 10 which will be employed in the descriptive example employed hereinafter to demonstrate the method of this invention. Document 10 employs only alpha-numeric information but the invention would work equally with graphic information or non-English alphabets. Before the description is undertaken further, it should be noted that the intent of this particular facsimile security system is the protection of "business confidential" and personal information, for example, which forms the bulk of facsimile transmissions for which some form of easily implemented security system is required. It is not intended to be employed with military classified documents which require greater security. Normal mail arrives at its destination in an envelope which can be marked "Confidential", or the like, signifying that it is to be opened only by the addressee. F acsimile transmissions, on the other hand, arrive without an envelope. At best, they have a cover sheet that is the first sheet of the transmission. Marking the cover sheet "Confidential" only acts as a flag to the receiver (and any other intermediaries between the receiver and the designated recipient) that the document contains information that might be interesting to read. The only way to avoid undesired reading of the materials is for the sender to call the intended recipient by telephone to advise that a confidential facsimile is about to be transmitted and for the intended recipient to go to the facsimile machine and retrieve the document page by page as it is received and transmitted. In this regard, the present invention provides a kind of invisible envelope for the documents. As depicted in Figures 2 and 3 and shown in the block diagram of Figure 4, the method of the invention comprises pattern dividing the document 10 into "A" and "B" portions such as the two patterns 12 and 14 of Figures 2 and 3, respectively. As will be noted, the patterns 12, 14 comprise "opaque" portions 16 and "transparent" portions 18 and are the complement of one another; that is, the opaque portions 16 of pattern 12 are the transparent portions 18 of pattern 14, and vice versa. The patterns, of course, can be any shape or design, as desired, as long as they are sized and shaped to divide the pixels of the document into groups that when transmitted and printed out form a total document which is unintelligible to the casual reader. While two complementary patterns 12, 14 (i.e. "A" and "B") are depicted and employed in the example, more than two could be used, if desired", to split the pixel groupings at the different transmissiontimes into smaller and less individually intelligible groups in the documents on the receiving end.

The "A" pattern group of pixels from the document 10 are then transmitted and received at the destination facsimile machine in the document 10' of Figure 5. The "B" pattern group of pixels from the document 10 are then transmitted and received at the destination facsimile machine in the document 10' ' of Figure 6. The two documents 10' , 10' ' as printed out on the receiving end as representing the time-shifted pattern-divided portions of the document 10 are then delivered to the intended recipient. The recipient then reconstructs the document 10 (i.e. opens the "invisible envelope") by copying one of the portions 10', 10'' onto a transparency. This can be accomplished easily employing any one of several products presently available commercially for the production of overhead projection transparencies on xerographic process photocopy machines. The transparency of the one portion is then overlayed over the other portion and the areas aligned to allow the entire facsimile 10' ' ' of the document 10 to be viewed by the recipient as indicated in Figure 7.

In its simplest embodiment, the portions 10' , 10' ' of a document 10 can be created by employing a transparent transport envelope 20 of the type generally employed for transporting irregular paper pieces, photographs, and the like, which will not "feed" in the normal manner through a facsimile machine. The envelope 20, of course, must be modified as shown in Figure 8 to accomplish the objectives of the present invention. The envelope 20 comprises a pair of transparent sheets 22, 24 hingedly joined together at their top edge 26 in the usual manner. To accomplish the objectives of the present invention, one sheet 22 has the "A" pattern 12 printed thereon and the other sheet 24 has the "B" pattern 14 printed thereon. It is preferred that alignment marks 28 be provided for properly aligning a document placed within the envelope 20 with respect to the patterns 12, 14. In use, the document 10 is placed in the envelope 20 with an edge in alignment with the alignment mark 28 and facing upward under the "A" pattern 12. The envelope 20 is then fed through the sending facsimile machine with the sheet 22 (and document 10 inside) being scanned through the "A" pattern. The document 10 is then placed in the envelope 20 with the same edge in alignment with the alignment mark 28 and facing upward under the "B" pattern 12. The envelope 20 is then fed through the sending facsimile machine with the sheet 24 (and document 10 inside) being scanned through the "B" pattern. This, of course, will normally require that the receiving facsimile machine be called twice as the connecting line will be lost while the document 10 is reversed within the envelope 20. For such reason, it may be more desirable to copy the document 10 in the envelope 20 in the two positions as described above on a photocopy machine to create the two portions 10' and 10' ' on the sending end and then send the copied portions 10' , 10' ' in sequence fromthe sending facsimilemachine without losing the line connection. In testing the method of the present invention in the above-described manner, the inventors herein found that there was a tendency for the document 10 to move and "squirm" within the envelope 20 during feeding through the facsimile machine. Any movement, of course, can causemisalignment problems when reconstructing the document 10 at the receiving end. By photocopying the portions 10', 10'' and feeding the photocopies through the facsimile machine, this problem is eliminated. The inventors also found that if the plastic envelope 20 is rubbed so as to create a static charge thereon, the sheets 22 and 24 tend to adhere to one another and hold the document 10 in place much more securely.

With regard to improved performance on the receiving end, the inventors found that the photocopying process typically introduces some distortion into the photocopy with respect to the original which was copied. For that reason, preferred performance will be obtained when practicing the method of this invention if both portions 10' and 10'' are photocopied on the same machine - one on paper and one on the transparency film - prior to overlaying them to create the composite facsimile document 10'''. It is also anticipated by the inventors herein that improved performance may be achieved if a white sheet of copy paper 30 is releasably attached to the top edge 32 of an associated transparency sheet 32 for use with this invention as depicted in Figure 10. The two sheets 30, 34 are fed through the photocopy machine together twice - once with the sheet of copy paper active to produce one portion 10', 10' ' and once with the transparency sheet 34 active to produce the other portion. The two sheets 30, 34 are then separated and overlayed to produce the composite facsimile 10' ' ' .

Where the document 10 is produced by a word processing system or the like in a computer, the separation of the document 10 into the two portions 10' , 10' ' for transmission can be accomplished within the word processing software or by a separate program which manipulates the document in memory between its input process and the printing thereof. For example, let us assume that the document as input comprises a document named FOX.DOC as follows:

The quick brown fox jumped over the lazy dog.

After FOX.DOC (a representative computer document name) is produced it can then be pattern manipulated on a line-by¬ line and character position-by-character position basis to create two new documents FOX1.DOC: T e u c rw o upd vr h a y o . and FOX2.DOC: h q i k b on f x j me o e t e l z dg

FOX1.DOC and FOX2.DOC are then printed in the normal manner and transmitted as the two portions 10' , 10' ' . As can be appreciated, when one is copied on a transparency and the transparency is overlayed onthe other, the original document FOX.DOC will be reconstructed as described above.

Another approach within the scope and spirit of the present invention that couldbe accomplished in the computer- generated environment is as follows . Assume that the original document FOX.DOC is as above, i.e. : The quick brown fox jumped over the lazy dog.

Assume then that the two new documents created by manipulating the FOX.DOC document are FOX1.DOC: Thehquickibrowndfoxejumpedaoverfthealazyxdog. and FOX2.DOC: X X X X X X X X

If FOX2.DOC as transmitted is copied to the transparency and overlayed on the FOX1.DOC document as .transmitted, it will appear as: TheXquickXbrownXfoxXjumpedXoverXtheXlazyXdog. which is now readable, although not a true reproduction of the original document. For this reason, this approach is not preferred.

The process of the present invention can also be easily incorporated into the software of so-called PC-fax and virtual fax packages that are now available under various trademarks such as, for example, APPLE-FAX. It can also be incorporated into a conventional facsimile transmitting/receiving device or a keyboard to facsimile (KeyFAX) device. This latter aspect of the present invention is depicted in Figure 9. With the KeyFAX device 36, alpha- numeric messages are input through a keyboard (not shown) and stored in a message memory 38 from which they are transmitted as pseudo-pages of facsimile documents. With PC-fax system 40, data and/or graphics are generated and stored in the message memory 38 which comprises page memory which is then transmitted in facsimile format as if scanned into thememory 38 from a facsimile scanner. These two types of devices/systems are already ready for conversion to incorporation of the process of the present invention through modification of the programming contained therein. In the case of a conventional facsimile machine, the scan data from the scanning unit 42 typically is transmitted as scanned. To implement the process of the present invention, a message memory 38 must be provided into which the scanned data from the scanning unit 42 is first stored. Since many facsimile machines are now including a memory for receiving facsimile data prior to printing, such memory can be employed for the message memory 38 without the need for adding additional memory. Similarly, in the Keyfax device 36 and PC-fax system 40 the desire to transmit a document as input in the "HideaFAX" mode of this invention can be indicated by means of a keyboard input or the like. With a conventional facsimile machine, a separate button 44 would have to be provided to indicate this desire. In any event, with each of these devices once the message to be transmitted is in the message memory 38 the output portion, as indicated by the dashed box 46, would have to implement logic as shown therein. In particular, after calling the receiving facsimile machine the logic must decide whether or not it is in the HideaFAX mode (as by testing the button 44) . If not, it is preferred that a cover sheet be generated and transmitted followed by the document pages in their input form. If the HideaFAX mode has been selected, it is preferred that a cover sheet be generated indicating the recipient as well as advising that the document which follows will comprise two copies of each page being the portions of the page as subjected to the HideaFAX process which will require reconstitution by the designated recipient. The logic then reads a page of the document from the memory 38 and transmits it as filtered with an "A" pattern. Such software filtering according to a designated algorithm is an easily implemented function. For example, with alpha-numeric documents from a KeyFAX device the above-described process of skipping characters can be employed with very little additional programming required. After the "A" pattern portion of the page of the document has been sent, the process is then repeated for the "B" pattern portion of the same page. As shown in the logic of Figure 9, the same process is repeated for each page of the document until the last page has been transmitted.

Note that, in all cases where the patterning of the document is affected by softwaremanipulation of the document as input, it is preferred that the software recognize control characters within the text of the document, employ them for turning the HideaFAX mode on and off within portions of the document itself, and remove the control characters from the document as transmitted. For example, the sequence "\B" could indicate "Begin HideaFAX processing." while the sequence "\E" could indicate "End HideaFAX processing. "

As a final note, if desired for the particular implementation, the reconstruction of the document 10 from the portions 10' , 10' ' could be accomplished by a computer at the receiving end. The first transmitted portion 10' could be received and stored in a page memory. The second transmitted portion 10' ' could then be overlayed by employing a software "transparency" thereof in the form of an XOR merging of the two portions. Such a computer implementation of the document reconstitution process at the receiving end is considered to be within the scope and spirit of the present invention and the term

"transparency" as employed in the description above and in interpreting that term as it may appear in the claims appended hereinafter.

The preferred document patterning device is based on a particular pattern construction as depicted by way of example in Figure 11. While a series of diagonal stripes are employed to create the complementary and mutually exclusive "A" and "B" patterns as described above, other patterns having the required characteristics could also be used with the patterning device to be described herein. For example, the pattern could consist of alternating white and transparent "crosses" where the width of the crossbars is equal to the depth of the crossbars. The only requirement is that the pattern of white and transparent portions 116, 118 be complementary along equal longitudinal shift distances . Again, as those skilled in the art will recognize, the pattern could be a radial pattern which is complementary in equal radial distances; however, most documents and copying devices are oriented to a rectangular structure and, therefore, the rectangular approach of Figure 11 is preferred.

What this all means is that the width d_t in the longitudinal direction along the pattern 120 of the transparent striped portions 118' is equal to the width d, in the longitudinal direction of the white striped portions 116'. Thus, as will be readily recognized and appreciated from a close inspection of the drawing of Figure 11, if a document is placed in any "A" position on a pattern 120 having the qualities described above and copied; and then, the document is moved longitudinally a distance d which is equal to d_j=d_z to a "B" position and copied, the two copies produced will be precisely registered partial documents just as if two separate patterns were employed. This phenomenon is employed herein to obtain the desired objective. Turning first to Figures 12 and 13, the document patterning device first comprises a rectangular frame 122 having the pattern 120 affixed to the bottom thereof so as to rest directly on the cover glass 124 of the photocopy machine being employed so as to space the document being copied above the cover glass to the smallest degree possible (to affect a minimizing of movement of the document from the focal plane of the scanning apparatus of the photocopy machine. The preferred frame 122 is of one of the tough plastics presently available and comprises an upper crossbar 126, a lower crossbar 128, and a pair of parallel side members 130. The pattern 120 is preferably of a very thin sheet of a tough transparent plastic such as polycarbonate which is glued or taped to the bottom of the frame 122 as depicted in Figure 13. The white stripe portions 116' of the pattern 120 are preferably applied by a silk screening process to the bottom surface of the pattern 120 so as to resist wear from the sliding process which takes place in using the device, as will be appreciated from the description which follows. The sliding member 132 employed to affect the desired longitudinal movement of the document being copied between the "A" and "B" positions is shown in a top view in Figure 14. The preferred.sliding member 132 is rectangular in shape and of a resiliently flexible plastic. Preferably, it is of white plastic (of a white as employed in the background elements of photocopy machines) or painted white. As will be appreciated shortly, this makes the sliding member 132 self- backgrounding for documents being copied. This is particularly useful for smaller documents such as checks, photographs, or the like. As best seen in Figure 15, a gripping lip 134 is attached along the bottom edge of the sliding member 132 whereby the sliding member 132 can be lifted and rolled back at the bottom towards the top in order to insert and remove documents . The material of the sliding member 132 at the top edge is formed into a longitudinal tab

136 having a longitudinal double keyhole slot 144 therein. The sliding member 132 is shown in a bottom view in Figure 15. A rectangular, transparent carrier sheet 138 is hingedly attached to the sliding member 132 adjacent the top edge thereof as with tape 140. The carrier sheet 138 is also preferably of a very thin, tough, plastic such as polycarbonate.

The patterning device of this application is shown assembled in Figure 17 where it is generally indicated as 142. The sliding member 132 is disposed within the frame 122 with the carrier sheet 138 resting on the pattern 120. In use of course, the frame 122 and pattern 120 are disposed on the cover glass 124 of the copier machine (not shown) as depicted in Figure 13. A document 114 to be copied to form the two partial documents 114' , 114'' is inserted between the carrier sheet 138 and the sliding member 132 by rolling back the sliding member 132 from the bottom as depicted in Figure 17. Note that the width of the sliding member 132 should be such with respect to the spacing between the side members 130 of the frame 122 that the sliding member 132 slides smoothly longitudinally within the frame 122 without any binding or yaw motion. As depicted in Figure 18, the tab 136 passes through a slot 160 between the upper crossbar 126 and the pattern 120 which can be provided by not glueing or taping the pattern 120 to the upper crossbar 126 of the frame 122 at that point. If desired (or if the thickness of the material employed for the tab 136 requires) , an actual slot 160 could be formed into the upper crossbar 126. Turning now with particularity to Figures 18 and 19, it can be seen that a detent and limit peg 146 carried by the upper crossbar 126 passes through the double keyhole slot 144. The peg 146 can be formed into the upper crossbar 126 or be inserted through the upper crossbar 126 as a separate item, as best suits the implementation and manufacturing technique employed for the device 142. Note that, as depicted in Figure 18, the length of the slot 144 is such as to limit the longitudinal movement of the sliding member 132 to the required distance d between the "A" and "B" positions with respect to the striped portions 116', 118' of the pattern 120 as described earlier with respect to Figure 11. The diameter of the peg 146 is chosen to be substantially equal to the diameter of the two holes 148 on the ends of the slot 144. Accordingly, as depicted in Figure 19, as the sliding member 132 is moved longitudinally (by pulling or pushing longitudinally on the tab 136) between one of the holes 148 and the other, the side portions 150 of the material of the sliding member must deform slightly in order for the peg 146 to pass therebetween. Thus, the peg 146 in combination with the slot 144 not only performs a longitudinal motion limiting function; but, additionally, functions as a detent tending to retain the sliding member 132 in either the "A" or "B" position for proper registration.

From the foregoing description, it should now be apparent how the patterning device 142 is used and how it functions. The device 142 is placed on the cover glass 124 of a photocopy machine and a document 114 to be copied is placed in it between the carrier sheet 138 and the slidingmember 132 and then the cover lid (not shown) of the photocopy machine is lowered onto the top of the frame 122 to hold the device 142 in position. To aid in this objective, one may wish to attach the pattern 120 to the bottom of the frame 122 with a tape having a high coefficient of friction or, alternatively, use such a tape on the bottom edges after gluing the pattern 120 to the frame 122. The tab 136 (which preferably is of a length to stick out from under the cover lid) is gripped and pulled or pushed to place the slidingmember 132 in either the "A" or "B" position. The detent action of the peg 146 in the slot 144 tends to pull the sliding member 132 into the selected position and hold it there. A first copy is then made. The tab 136 is then gripped and pulled or pushed to overcome the detent action of the slot 144 and peg 146 and place the sliding member 132 securely in the other (i.e. "A" or "B") position and a second copy made. These two copies are the desired partial documents 114', 114'' as desired.

When copying a document 114 with the device 142 of Figure 17 to make two copies which are the desired partial documents 114', 114'' for secure transmission, the document 114 is shifted longitudinally by the distance d of the pattern offset as described above. Normally, where the distance d is in the order of a half inch and the document 114 is a standard document having inch margins at the top and bottom, the shifting of the document 114 will not cause a problem of lost data at the top or bottom (depending on the initial placement of the frame 122 on the cover glass 124 of the photocopy machine being employed) . Where this is a problem, however, the alternate approach shown ghosted in Figure 17 can be employed. An attaching member 152 is permanently affixed to an area of the photocopy machine (on the cover glass 124 or adjacent thereto) over which the tab 136 will overlap. The attaching member 152 contains one half 154 of a touch fastener material such as that sold under the trademark Velcro on the upper surface thereof and can be conveniently attached, for example, with an adhesive backing thereon of a type well known in the art and often used for such purposes. The mating half 156 of the touch fastener material is adhesively attached to the bottom of the tab 136. For convenience in using this approach, it is also convenient to have a position shifting rod 158 projecting outward from one of the side members. The use of a high friction material on the bottom of the frame should also be avoided and the cover lid of the photocopy machine should be left raised with the document backgrounding functions being performed by the white slider member 132. To employ the device 142 in this mode, the slider member 132 is positioned over the cover glass 124 of the photocopy machine such that it will be fully copied in the area to be occupied by the document 114. The touch fastener halves 154, 156 are then pressed together to attach the tab 136 to the photocopy machine. The frame 122 is then slid to either the "A" or "B" position (the slider 132 remaining fixed) . The document 114 is then inserted between the slider member 132 and the carrier sheet 138 in the usual manner and copied. The frame 122 is then slid to the other of the "A" and "B" positions (the slider 132 again remaining fixed so that no shifting of the document 114 on the cover glass 124 takes place) and the second copy made. Thus, there is no potential for loss of data regardless of the lack of top and bottom margins on the document 114 and the size of the pattern displacement distance d. Additionally, while the preferred embodiment as described hereinbefore is of a simple construction for ease of manufacture and low cost, a more complex structure could be employed to affect the sliding movement between the frame and the sliding member. For example, the sliding member could be incorporated into a second frame. The side members could be in the form of rods or bars which pass through the second frame. Also, the movement of the sliding member could be affected though an intermediate device such as a rod or lever. Separate mechanical detents could be employed. All these variations have been considered and rejected in favor of simplicity in the preferred embodiment; however, they are considered to be within the scope and spirit of the invention as disclosed herein.

The above-described method is extended using a preferred transparency by the additional steps depicted in Figures 20 and 21. The partial document 214' is placed on a solid surface with the preferred transparency 220' (to be described shortly) on top of it and the two aligned into proper registration. While pressing down on the partial document 214' and transparency 220' to hold them in registration, an adhesive 222 is activated to bond the partial document 214' and transparency 220' together against further relative movement.

The preferred adhesive photocopyable transparency 220' is shown in Figure 22. The transparency 220' comprises a rectangular sheet of a photocopyable plastic material 224 of a type well known in the art for such purposes . The plastic material 224 has score lines 226 formed along the side edges 228 and parallel thereto. The score lines are located about 1/4 to 3/8 inch from the edges 228 and can be formed by any of several well knownmanufacturing techniques well known in the art such as mechanical scoring or laser cutting. The, strips 230 between the score lines 226 and the edges 228 and a portion on the inner sides of the score lines 226 have a thin, transparent, adhesive tape 232 applied thereto. Thus, the transparency 220' will feed through a typical photocopy machine without problem.

In use, when the transparency 220' has been placed in registration on the partial document 214' and the two are being held together as described above, the strips 230 are lifted as depicted by the arrow 234 in Figure 23 to break the transparency 220' along the score lines 226. The tape 232 is then folded back as depicted in Figure 24 and the strips 230 peeled therefrom. The tape 232 is then used to adhesively attach the transparency 220' to the document portion 214' as depicted in Figure 25.

The adhesive 222 of Figure 21 can also take other forms as depicted in Figures 26-28. Since the plastic material 224 used for such photocopyable transparencies is quite thin, it can be rolled back at the corners and/or along the edges 228, for example, to activate an adhesive strip 236 or spot 238. In this embodiment, the score lines 226 are unnecessary. A two-sided adhesive material 240 has its protective covering (not shown) removed and it is adhesively attached with its exposed adhesive surface to the bottom of the plastic material 224 in a desired position. The other protective covering 242 is left on. Again, using thin materials for the adhesive material 240 and remaining protective covering 242, the transparency 220' should pass through a typical photocopy machine without incident. As depicted in Figure 29, with this approach it is preferred that the protective covering 242 have a tab 244 extending outward therefrom which can be grasped and pulled as indicated by the ghosted position and arrow 246 of the drawing figure. A string, or the like, could also be attached to the edge of the protective covering 242 to function in the manner of the tab 244. When copying onto the transparency 220', the tab 244 should face towards the bottom of the transparency 220' as it passes through the photocopy machine so as not to catch and cause a jam. With the tab 244, the edge of the transparency 220' does not have to be lifted as high in order to remove the protective covering 242 from the adhesive material 240. When the transparency 220' is positioned over the partial document 214' and with the two held together, the tab 244 is simply grasped and pulled to pull the protective covering 242 off the adhesive material 242 and out from between the transparency 220' and the partial document 214' so that the adhesive material 242 can bind the two together. A plurality of spots 238 of the adhesive material 242 could be disposed along one (or both) of the side edges 228 of the transparency 220' to be covered by a single strip of the protective covering 242. For example, four spots 238 could be placed in the four corners of the transparency 220' with one pull strip of the protective covering 242 along the top edge and another along the bottom edge.

Wherefore, having thus described our invention, what is claimed is:

Claims

1. A system for sending a document by facsimile, in a manner which prevents unauthorized casual reading of the document at a receiving site CHARACTERIZED BY: a) at a sending site, means for spatially dividing and transmitting the document as two portions each containing mutually exclusive parts of the document chosen such that each of the portions is independently unrecognizable for casual reading purposes; and, b) at the receiving site, means for overlaying the received portions in spatial registration to reconstuct a facsimile of the document in a recognizable and readable form. .

2. The system according to claim 1 characterized in that said means for spatially dividing and transmitting the document as two portions includes: a) a computer memory file containing the document; and, computer programmeans, for accessing the file and for forming a first portion document which is transmitted containing parts of the document chosen such that the first portion document is independently unrecognizable for casual reading purposes, and for accessing the file and for forming a second portion document which is transmitted containing the parts of the document not included in the first portion document; b) means for optically filtering the document through a first portion mask defining the areas of the document to be copied into the first portion document; and, means for optically filtering the document through a second portion mask defining the areas of the document to be copied into the second portion document; or c) a device for photocopying the document employing a standard photocopy machine having a cover glass upon which documents to be copied are placed to produce two partial documents each containing portions of the document which are complementary and mutually exclusive, said device including: a transparent sheet sized to be placed on the cover glass and having a pattern thereon of white and transparent portions which are complementary along longitudinally equal shift distances; holder means for holding a document over said pattern and disposed on said transparent sheet; and, movingmeans formoving saidholder means between a first position and a second position located longitudinally at said equal shift distance from said first position.

3. The system according to claim 2 b) characterized in that said means for optically filtering the document through a portion mask defining the areas of the document to be included each comprises: a) a first document transport for holding the document as it is optically scanned having a transparent cover over the document containing the first portion mask as opaque areas thereon; and, b) a second document transport for holding the document as it is optically scanned having a transparent cover over the document containing the second portion mask as opaque areas thereon.

4. The system according to claim 3 characterized in that: said irst and seconddocument transports comprise a single document transport having first and second transparent covers hingedly joined at a top edge wherein said first cover contains the first portion mask as opaque areas thereon and said second cover contains the second portion mask as opaque areas thereon.

5. The systemaccordingto claim 2 c) characterized in that said holder means is slidable on said transparent sheet between said first and second position and additionally comprising: a) stop means for preventing said holder means from sliding longitudinally a distance longer than between said first and second positions; b) detent means for resiliently holding said holder means in said first and second positions; or c) combined stop and detent means for preventing said holder means from sliding longitudinally a distance longer than between said first and second positions and for resiliently holding said holder means in said first and second positions.

6. The systemaccordingto claim 5 c) characterized in that said combined stop and detent means comprises: a) a double keyhole slot longitudinally disposed in said holder means and having circular holes on ends thereof separated by a connecting slot of a width less than a diameter of said holes; and, b) a peg carried by said transparent sheet and of a diameter equal to said holes disposed through said double keyhole slot.

7. The system according to claim 2 c) characterized by: a) a rectangular frame having said transparent sheet attached to a bottom surface thereof and including parallel side members spaced such that a document to be photocopied can be disposed between them; and wherein., b) saidholdermeans is slidably carried by said rectangular frame.

8. The system according to claim 7 characterized in that said holder means comprises: a) a rectangular. top member slidably disposed between said side members; and. b) a transparent, rectangular carrier member slidably disposed on said transparent sheet and attached to said topmember for slidingmovement in combination therewith whereby a document to be photocopied can be placed between said top member and said carrier member to move in combination therewith.

9. The system according to claim 8 characterized in that: a) said carrier member is hingedly attached to said top member adjacent a top end thereof and said top member is resiliently flexible whereby said top member can be rolled away from said carrier member towards said top end to allow a document to be placed between said top member and said carrier member or be removed therefrom; or b) said top member includes a gripping tab means extending beyond said frame for gripping to move said top member between said first and second positions.

10. The systemaccording to claim 9 b) characterized in that said gripping tab means and said frame include: combined stop and detent means for preventing said topmember from sliding longitudinally a distance longer than between said first and second positions and for resiliently holding said top member in said first and second positions.

11. The system according to claim 10 characterized in that said combined stop and detent means comprises: a) adouble keyhole slot longitudinallydisposed in said gripping tab means and having circular holes on ends thereof separated by a connecting slot of a width less than a diameter of said holes; and, b) a peg carried by said frame and of a diameter equal to a diameter of said holes disposed through said double keyhole slot.

12. The system according to claim 9 b) characterized by: means for releasably attaching said gripping tab means to a surface of the photocopy machine whereby said frame can be moved relative to said top member to affect relative movement between said first and second positions.

13. The system according to any preceding claim characterized in that said means for overlaying the portions in spatial registration to reconstuct a facsimile of the document in a recognizable and readable form comprises: a) a transparent medium; and, b) means for copying one of the document portions onto said transparent medium whereby by physically placing said transparent medium containing said one document portion copied thereon onto the other portion and visually aligning the position of said transparent medium on the other portion to place the document portion on said transparent medium into alignment with the other portion the two portions can be made form a facsimile of the document which can be recognized and read.

14. The system according to any one of claims 1 to 12 characterized in that said means for overlaying the received portions in spatial registration to reconstuct a facsimile of the document in a recognizable and readable form includes an adhesive photocopyable transparency for use in a secure facsimile transmission system wherein one of two partial documents each containing portions of an original document which are complementary and mutually exclusive is photocopied onto the transparency and overlayed on the other of the two partial documents in registration therewith to recreate the original document, including: a) a rectangular sheet of a transparent plastic material having a surface for accepting and holding a photocopy image; b) an adhesive material disposed at an edge of said sheet of plastic material; and, c) a removable protective coveringdisposed over said adhesive material so as to allow the transparency to pass freely through a photocopy machine and be slid on the surface of a document without said adhesive material interfering therewith whereby after photocopying the one of two partial documents onto the transparency and placing it in registration on the other of the two partial documents said protective covering can be removed in place to bond the transparency to the one of the two partial documents.

15. The system according to claim 14 characterized in that: a) said adhesive material comprises a strip adhesive tape adhesively disposed on a top surface of said sheet of plastic material along a side edge thereof; and, said sheet of plastic material is frangible along a line disposed under said strip of adhesive tape whereby an outer edge of said sheet of plastic material comprises said removable protective covering and is removable by breaking said sheet of plastic material along" said line and peeling said outer edge from said adhesive tape; or b) said adhesive material comprises an adhesive material disposed on a bottom surface of said sheet of plastic material at a side edge thereof; and, said removable protective covering comprises a flexible sheet of material covering said adhesive material and which can be grasped at an edge thereof and peeled from said adhesive material.

16. The system according to claim 15 b) characterized in that: a) said adhesive material comprises a strip of adhesive material disposed along a side edge of said sheet of plastic material; and, said removable protective covering comprises a strip of said flexible sheet of material covering said strip of adhesive material; b) said adhesive material comprises a plurality of spots of adhesive material disposed along side edges of said sheet of plastic material; and, said removable protective covering comprises a plurality of spots of said flexible sheet of material covering respective ones of said spots of adhesive material; c) said adhesive material comprises a plurality of spots of adhesive material disposed along side edges of said sheet of plastic material; and, said removable protective covering comprises a strip of said flexible sheet ofmaterial covering said plurality of said spots of adhesive material; or d) a pull tab extending outward from said removable protective covering for gripping to peel said removable protective covering from said adhesive material.