CA2050938A1 - Thermally-activated receiving medium for use in a facsimile transmission system - Google Patents

Abstract

A printing medium for the printing of images thereon to form a document by the printer of a standard facsimile machine in a manner which renders the document unreadable to a casual observer.
There is a strip of a flexible printing medium receivable by the facsimile machine for passage therethrough past the printer thereof.
The printing medium has a surface for receiving an image from the printer. Additionally, there is a strip of an obscuring medium removably attached to the printing medium along an edge thereof in a manner which will allow the obscuring medium to pass through the facsimile machine in combination with the printing medium. The obscuring medium has an obscuring portion covering a printing surface of the printing medium upon which the printer prints images for rendering printing of the printing medium unreadable to a casual observer. Four embodiments are disclosed for use in both thermal and plain paper facsimile machines. An addressing scheme to allow identification of the addressee without opening the ''envelope''' is shown. One version can be employed to provide plain paper output on a standard facsimile machine with a thermal printhead by simply replacing the thermal paper thereof.

Description

: ` 2~938 THE~MALLY-ACTIVATED RECEIVING MEDIUM FOR USE
IN A FACSIMILE TRANSMISSION SYSTEM
Backaround o~ t~e Inv~n~iQ~:
This invention relates to facsimile transmission systems for sending a document between a sender and a receiver byfacsimileinamannerwhich prevents unauthorized casual reading of the document, and, more particularly, to a printing medium for the printing of images thereon to form a document by the printer of a standard facsimile machine in a r~1anner which renders the document unreadable to a casual observer As an additional benefit, one embodiment provides plain paper output from a standard thermal printhead facsimile machine.
The sending of documents by facsimile is an ever ~5 increasing phenomenon. On the positive side, ~acsimile transmission is fast, accur~te, and inexpensiv~. On the negative side, it is like sendin~ a po~tcard; that is, everyone in ~he chain of delivery can read ~h~ cont~nks oE th@
transmission This i5 particularly annoying where the transmitted document contains personal or privileged inlormation.
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. Facsimile transmissions,onthe otherhand,arrivewithoutanenvelope.
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 bytelephonetoadvisethat a confidential facsimile is about to be tra~smitted and for th~ i~tend0d recipient to go to the facsimile machine and retrie~e the document page by page~ as it is received and transmitted.

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An additional problem of the bulk of contemporary facsimile machines is the use of thermal paper in order to keep the cost of the apparatus down. In order to provide so-called "plain paper" output, a facsimile machine must incorporate the complex and expensive apparatus for xerographic printing, or the like, which drives the cost of the facsimile machine beyond that which most users are williny to pay.
Whatisalsoneededisa securityfacsimile transmission system wherein the security aspects of the transmission can be under the control of the receiver.
Wherefore, it is the object of this inventionto provide a facsimile transmission receiving medium onto which a received facsimile from a standard facsimile machine can be lS printed in a manner which will make the resul~ant copy virtually unreadable to the casual observer.
It is another obj~ct of thi~ invention to provlde ~
security facsimile tran~mission sy~tem wherein th~ s~cur~ty aspects of the transmission are under the control of the receiver.
It is stiLl another object of this invention to provide a facsimile transmission receiving medium onto which a received facsimile can be thermally printed in a manner which will make the resultant copy virtually equal in print quality to that produced by a plain paper copy or facsimile machine.

Description of the ~rawin~s:
Figure l is a simplified drawing of a document received and printed according to prior art methods and materials where the resultant printing is readily readable by the casual observer.
Figure 2 is a simplified drawing depicting the printing process and materials of a prior art thermal paper facsimile machine Figure 3 is a simpli~led drawing depicting the printing process and materials of a prior art plain paper facsimile .

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machine.
Figure 4 is a simplified drawing depicting the printing process and materials of a plain paper ~acsimile machine employing themethods andmaterials of the presentinvention.
Figure 5is a simpli~ied drawing depicting the printing process and materials o~ a thermally operated facsimile machine employing the methods and materials of the present invention in a first embodiment.
Figure 6 is a simplified drawing depicting the printing process and material~ of a thermally operated facsimile machine employing the methods and materials of the present invention in a second embodiment.
Figure 7 is a simplified drawing depicting the printing process and materials of a thermally operated facsimile machine employing the methods and materials o~ th~ present invention in a third embodiment.
Figure 8 is a simplified plan view o~ é~ trnn~par~nt printing medium on a ~ackin~ sheet havln~ an int~rE~rence pattern thereon accordin~ to one asp~ct o~ the present invention.
Figure 9 shows the printing medium of Figure 8 with a message printed on the transparent portion depicting how the interference pattern seen through the transparent portion renders the message unreadable to the casual observer.
Figure lOis an enlarged (not to scale) simplified cross section oftheaddressablethermal printingsecuritypaper of this invention. -Figure 11 is a simplified drawing o~ a document ~s it appears when printed on the addressable security paper.
Figure 12 is a simplified block diagram of a computer-based system for placing the addressee's identity along an edge of a document.to be transmitted to addressable security paper.
Figure 13is an enlarged (not to scale) simplified cross section of addressable thermal printin~ security pap~r o~
this invention according to an alternate embodiment.

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~escription of ~hQ~L~errçdL~m~o~iment:
Turning first to Figure 1, a document 10 received and printed according to prior art methods and materials is S depicted wher~ the resultant printing 12 is readily readable by the casual observer. As mentioned earlier, in a typical prior art standard facsimile machine as available in the marketplace today, the printing 12 of Figure 1 is accomplished in one of two ways. As depicted in Figure 2, the most common way is the use of a thermal printhead ~4.
According to latest figures, this approach accounts for approximately75%ofthefacsimilemachinespresentlyinuse The printing medi-~m is a roll of paper 16 having a thermally activated coating 18 thereon The printhead 14 extends transversely across the width of the paper 16 which moves under the printhead during the printlng proce~s. The printhead 1~ comprlses a plurali~y of heating resls~or9 ~not shown) which can be lndividually he~ked by the appllcat~on of a current thereto. When a resistor of the printhead 14 at a particular pixel location is activated and heated to a threshold temperature, the coating 18 thereunder is turned black, as indicated at 20 in the drawing of Figure 2, thereby creating a visible spot. In a plain paper facsimile machine (as in a xerographic process photocopy machine or a so-called "laser printer"), the process of Figure 3 tshown in greatly simplified form) takes place. The image to be created on a sheet of paper 16 is created by the depositing of toner 22 from a toner head 24 (or the like) onto the paper 16. It is thereafter "fused into the surface of the paper 16 by a heating process. How these processes are accomplished employing the printing mediums of this invention to create non-readable images will now be described.
Turning first to Figure ~, a security medium, generally indicated as 26, is shown employed with a plain paper facsimile printing system such as that oE Figure 3. T

, W090/l32()~ PCT/US9~/00886 _5_ J;~ g he printing medium 26 comprises a transparency 28 of the type useable in a s~nder-initiated securityfacsimile system. The transparency 28 has an upper surface 30 adapted to receive a toner image and have it thermally fused thereto. A backing sheet 32 is attached to the bottom of the transparency 28.
Preferably, the backing sheet 32 is of paper and comprises the"tab" coveringtheadhesivematerial(which wasmentioned above) removably holding the backing sheet 32 to the transparency 28 in a manner to be described in greater detail shortly so that the medium 26 can also be used as a "FaxOver"
in the sender-initiated security facsimile system and thereby serve a dual purpose. The top surface 34 of the backing sheet 32 has an interference pattern thereon (not shown in this drawing) which interferes with the ability of a casual observer to read an image on the upper sur~ace 30 Oe the transparency 2~ s~ince the in~erference pattern i9 also seensimultaneously withthelmacJe Theinterferenco p~ttern is preferably a patter-n of lines which creates a confusion factor As those skilled in the art will readily appreciated, it could also be a regular pattern of some sort or a solid dark color substantial}y the same as that of the toner 22. To view the image, the backing sheet 32 is replaced with a sheet of white, which makes the image visible against the white background.
Turning now to Figure 4, a security medium, this time generally indicated as 26', is shown employed with a thermally operated facsimile printing system such as that of Figure 2. The printing medium 26' a~ain comprises a transparency 28'. In this embodiment, however, the 30- transparency 28' has a heat-activated coating ~8' on the upper surface 30 thereof which is adapted to be thermally activated in the manner of the coating 18 on the paper 16 of Figure 2. The result of the printin~ operation by the prin~head 14 is, th~refore, substantially identical to that of the prior embodiment; that is, black images (i~e~
activated''black''portions ~0') created onthe top surface 30 ~ . :~.. : . . , .. . . : , .

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of a transparent sheet (i.e the transparency 28'). A paper backing sheet 32 is again attached to the bottom of the transparency 28' and also again the backing sheet 32 preferably comprises the "tab" covering the adhesive material so that the medium 26' can also be used as a "FaxOver" in the sender-initiated method and thereby serve a dual purpose. The top surface 3~ of the backing sheet 32 again has an inkerference pattern thereon so as to interfere with the abiliky of a casual observer to read an image on the upper surface 30 of the transparency 28'. As in the prior embodiment, to view the image, the backing sheet 32 is replaced witha sheet of whiteto make the black image visible against a plain white background.
Two alternate methods and materials for use with the thermally operated printing process of Figure 2 are shown in Figures 6 and 7, In th~:smedium 26'' of Figure 6, ~h~ paper ~6 having the prior art ht~at activated coating 18 th~roon has a removeable, thin, opa~ue, h~a~ tran~er medium 36 thereon.
Alternatively, the transfer medium 36 can be translucent or have an interference pattern printed thereon. The object is to be unable to see through the medium 36 and easily.read images produced on the paper 16 in the coating 18 thereof.
The preferred medium 36 is a thin plastic impregnated with a powdered or finely granulated metal having a high index of thermal conductivity such as aluminum. Note that since the thermal facsimile machines are typically set up to employ a roll printing medium which is cut to lengths by a built in' rolling cutter, the plastic of the medium must be a frangible material which can be cut by a rolling cutter or it will jam the cutter. Thus, when the printhead 14 heats a particular pixel position, the heat generated is passed quickly and vertically through the medium 36 to activate the adjacent pixel position of the coating 18 and thereby create a vi~ible spot (i.e. an activated and black region 20) ak that position, To view the document in this embodiment, the transfer medium 36 must be removed to expose the underlying WO90/13201 PCr/US90/00~86 ` ~ 3 ~ ~

paper 16 with the printing thereon.
In the medium 26''' of Figure 7, a plain white paper is employed as the paper 16. A transport medium 38 having a heat transferred ink 40 thereon is disposed over the paper 16.
Such materials are known in the art and typically are employed as the "ribbon" of a plain paper thermal printer.
The "ink" 40 is actual:Ly a colored wax-based material which is non-trans~erable ak standard temperature; but, which melts and then transfers and fuses to the surface ofthe paper 16, as at 38, when subjected to a temperature substantially the same as that employed to activate the coating 18 as described earlier herein. While in printer ribbons the medium 36 is t.ypically o~ a thin tough plastic such as Mylar, or the like, in this application it is preferred that the lS transport medium 38 be of a less costly (and ~rangible) material such as a lightweight paper. To view the docum0n~
in this embodLment a~er printincJ, the transport medlum 3~
must be removed to expose kho prlnting on the und~rlying paper 16. It is preferred (but not necessary) that an additional obscuring means be added to the transport medium 38 in addition to that provided by the ink 40. This can be provided by printing an interfering pattern (which as previously can include a solid color) on the top surface of the transport medium 38 opposite the ink 40. It is this embodiment which provides the additional benefit of providing plain paper output from a standard facsimile machine having a thermal printhead. Thus, any thermally printing facsimile machine can be converted to plain paper output by simplyreplacing the thermal paper thereofwith the medium 26''' of Figure 7.
Turning now to Figures 8 and 9 the operation o~ the preferred dual-purpose transparency 28, 28' with a backing sheet 32 as described with respect to the embodiments of Figures 4 and 5 will now be addressed in greater detail. The transparency 28, 28' has a strip of adhesive material 44 adjacent at least one edge. Preferably, the adhesive .. .. ... .

WO90/13201 PCT/VS90/0~886 2a~938 material ~4 is disposed at the top edge (which is the leading edge through a facsimile machine's print path). If desired, the adhesive ~aterial 44 can be employed along the top and bottom edges or even all four edges to create a true "envelope" for each page of a received facsimile document.
If desired, the backing sheet 32 can be held to the transparency 28, 28' over the entire surface thereof such as by using one of the easily relea~ed adhesives presently available for use in temporarily and releaseably at~aching a piece of paper to a surface (including another piece of paper) without causing damage thereto when removed. The backing sheet 32 is attached to theother side of theadhesive material 42, Thus, the backing sheet 32 forms an ex~ended "tab" as referred to in the above-referenced co-pending '975 application, Preferably, the backing sheet 32 has a line oE
perforations ~6 tran;sversely thereacross adjacent the adhesive material ~4 such that the backing sheet 32 can be easily separated, The perforations ~6 divide the backing sheet 32 into an attaching strip ~8 and an obscuring portion 50, It is also pre~erred that additional transverse perforations 46' be spaced vertically along the length of the backing sheet 32 so that a portion can be removed on first sheets in order to see and read the identity of the intended receiver. Where an adhesive fastening along the side edges is employed, vertical perforations adjacent theretoare also preferred, Of course, where a facsimile cover sheet is employed (as is done according to good facsimile etiquette), the entire backing sheet 32 can be removed from the first ~i.e, cover) sheet to identify the addressee. It should be noted in passing that in the embodiments of Figures 6 and 7 the paper 16 is preferably attached to the overlying heat transfer medium 36 and transport medium 38, respectively, by adhesive fastening along the side edges with adjacent perforations for easy separation. In all cases, it is preferred that the perforations 46, ~6', etc, be ~ormed by a laser cutting process which separates easily and produces no ... ~ . .: . .. . . . . . . .. .

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bits of paper to get into working parts of adjacent electromechanical apparatus. As can be seen from the drawings, the interference pattern 52 is contained in ~he obscuring portion S0 over the area which can contain image on the overlying transparency 28, 28'. The effect of the interference pattern 52 can be seen in Figure 9 where the expression "Now is the time for all good men to come to the aid of their party", generally indicated as 54, has been printed on the transparency 28, 28'. As can be seen, the interference pattern 52 makes the reading of the expression difficult to impossible -- at least to the casual observer, who is the intended party to be excluded from reading of documents by the present invention.
In the preferred embodiment, the attachin~ strip ~8 is lS white in color so as to activate any copy machine with which it is used in its dual mode of use requiring same, Also in the preferred embodiment, th~ back o~ the obscuring portion 50 i9 white so as to also provlde the necessary white baclcground necessary for reading an im~ge on the transparency 28, 28'.
To use the preferred embodiment for viewing the image, the obscuring portion S0 is removed at the perforations 46 and reversed to use the white back side. The attaching portion is then peeled from the adhesive material 44 and the adhesive material 44 used to attach the white back side of the obscuring portion S0 to the transparency 28, 28' whereby the image is made visible.
A preferred aspect of the invention in all embodiments employed for security purposes is to initially fasten the printing medium to the obscuring medium in a manner which will disclose if the obscuring medium has been removed from the printing medium sufficiently for a document printed on the printing medium to be read.
As can be appreciated, where there is only one person (or set of persons with like security interests) receiving documents on the above-described paper, identi~ying the addressee is not a concern Documents are delivered to the WO90/l3201 PCT/US90/00886 2~sa~.~38 receiver and then the cover sheet is removed. Where the addressee is not known, however, the paper presents more of an inconvenience. If standard facsimile etiquette is followed, each document (of one or more pages) is preceded by S a cover page designating the recipient. In such case, the cover sheet of the cover page is simply removed to reveal the addressee Where no cover page is employed, the receiving station personnelmus~ use care in removing only a sufficient portion of the cover sheet of the ~irst page as required to determine the addressee.
Inmanyinstances,thereceiving station wouldprefer to know the identity of the addressee without resort to opening anything, in whole or in part. For example, many hotels are now providing both incoming and outgoing ~acsimile services for their guests. To provide the conEidential benefits thereof, they would ~e likely to use the above-describqd paper. As a conveniencc to them and as evidence o~ ~ complete maintenance o~ security, however, they would preear to have the addressee identified on ~he out3ide of the "envelope" as in a standard mail delivery. A provision for accomplishing that goal according to the present invention will now be described.
An edge of a thermal security paper of the type described above and modified according to the addressability aspects of this invention is shown in cross section in Figure 10 where it is generally designated as 110'. It should be noted with particularity that the drawing is not to scale.
The coatings employed therein, in particular, are shown greatly enlarged in order to make the structure of the psper 110' in general more understandable and apparent. The paper 110' comprises a cover sheet 114 disposed over a paper backing 112. The cover sheet 114 is preferably attached to the paper backing 112 along the edges thereof with an adhesive 130. The cover sheet 114 is perforated at 124 adjacent the edge of the adheslve 130 to allow the center portion of the cover sheet 11~ which is disposed overthe text ' " ''.

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WO90/13201 PCT/US90t~0886 . ` 2 ~ ~ ~ 9 ~ 8 128 of a document 126 to be removed quickly, easily, and neatly. The cover sheet 114 is coated on the side facing the paper backing 112 with a heat transferable ink 116 as in the basic paper described earlier herein. In the preferred paper 110', however, the coating of ink 116 is only between the perforations 124. The other side (i.e. the top side) of the cover sheet 114 has a strip of a coating of a thermally activated material 132 such as that used to coat prior art "thermal" facsimile paper. A separate strip of material could,of course,be used;however, the manufacturingprocess is simplified by merely coating the opposite sides of the cover sheet 114 with the ink 116 and thermally activated material 132i.n~heirrespective positionsand then~astening the coated cover sheet 114 to the paper backing 112 with the adhesive 130 at the edges ~hereo~. To provide for uniorm rolling of the pap~r 110' into a roll ~or supply purpo9e3~ it i5 prefcrr0d that th0r~ b~ s~rip~ of th~ thermally act~vated material 13~ along both edge.s and that the thickness of the coating of the thermally activated material 132 be substantially identical to that of the coating of ink 116.
As depicted in Figure 11, if the addressee is designated along the edges of the original document, the addressee portion of the original document will be printed on addressee label formed on the edges of the paper 110' by the strip of thermally activated material 132 along the edges.
While the addressee could be added to the edge of a document by hand or typewriter (by inserting the document sideways into the machine), as depicted in Figure i2, a computer approach could be employed to add the addressee portion to computer-created documents intended for transmission to the paper 110 ! of this embodiment. W:lthin the computer 134, the originating program 1~6 (such as a word processor) gets its inputs from a keyboard 138 and Creates a document 126 in memory lgO ~o be printed by the printer 142.
The security software 144 also receives its addressee information from the keyboard 138 and uses that information , :

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to modify the document 126 and place the addressee information along the edges as depicted in Figure 11. The modified docu;nent 126 is then printed by the printer 142 and transmitted by the facsimile machine. Note that it is 5 preferred that the security software 144 position the addressee information 146 sideways along both edges of the document 126 where the preferred pap0r 110' has strips of the thermal coating 132. If desired, the security software 144 could not only print the addressee information 1~6 on the 10 first sheet of a multi-page document; but additionally, count the number of pages in the document 126 within memory 140 and include appropriate page information along with the addressee on each page. For example, a page might include the message "PAGE 2 OF 4" as part of the addressee in~ormation 15 1~6. In this way, a security document w~ich became mixed with one or more other do~ument~ could be ~uickly and easily sorted into it3 various pag~
Finally, as d~picted ln Fl~ure i3, ln th~3 c~s~ of the above-described thermal security fac~imile paper wherein the 20 cover sheet comprises a thermally conductive material which transfers heat to a standard thermal paper acting as the paper backing and having a coating of thermally activated material thereon, the cover sheet can be made transparent and merely have no interference pattern along the edges so that 25 addressee information can be viewed therethrough. Where that is not possible, the preferred approach is the same as describe above wherein strips of the thermally activated material are disposed on the top surface of the thermally conductive material of the cover sheet along the edges 3û thereof.
Wherefore, having thus described our invention, what is claimed is:

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Claims (8)

1. A printing media for a facsimile transmission system whereby a document is sent between a sender and a receiver by facsimile and printed by a thermal printhead of a facsimile machine at the receiver, CHARACTERIZED BY:
a) a strip of a flexible printing medium receivable by the facsimile machine for passage therethrough past the printhead thereof, said printing medium having a printing surface for receiving an image from the printhead;
and, b) a strip of a covering medium disposed over a surface of said printing medium so as to pass through the facsimile machine in combination with said printing medium, said covering medium having a obscuring portion covering a printing surface of said printing medium upon which the printer prints images, said obscuring portion including means for causing heat produced by the printhead at positions of images to cause printing of said images at corresponding positions of said printing surface.

2. The printing media of claim 1 characterized in that:
a) said printing medium is a thermal paper having a top surface having a coating thereon which changes to a dark and visible color in response to heat; and, b) said covering medium is a covering sheet covering said top surface of said thermal paper, said covering sheet having a high index of thermal conductivity and capable of quickly transmitting heat from the printhead vertically through said covering medium to said coating on said thermal paper, said covering sheet being of a frangible material whereby said covering sheet can be cut by a transverse cutter of a facsimile machine which cuts roll media into sheet lengths.

3. The printing media of claim 1 characterized in that:

a) said printing medium is a plain paper having a top surface; and, b) said covering medium is a covering sheet covering said top surface of said plain paper, said covering sheet having a heat-transferable ink coating on a bottom surface thereof facing said top surface of said plain paper whereby when the printer applies heat to said covering medium said ink adjacent thereto is transferred from said covering medium to said top surface of said plain paper, said covering sheet being of a frangible material whereby said covering sheet can be cut by a transverse cutter of a facsimile machine which cuts roll media into sheet lengths.

4. The printing media of claim 1 characterized by:
a coating of a heat-activated material disposed along a strip adjacent a side edge of a surface of said covering medium opposite said printing surface, said material being a material which changes to a dark and viewable color upon the application of heat at a pixel position thereof by the thermal printhead of the facsimile machine whereby addressee information can be printed on said covering medium and viewed without removing said covering medium from said printing medium.

5. The printing media of claim 4 characterized by:
said coating of a heat-activated material being disposed along strips adjacent two side edges of said covering medium whereby the printing medium rolls evenly into a supply roll.

6. The printing media of claim 3 characterized by:
a coating of a heat-activated material disposed along a strip adjacent a side edge of a surface of said covering medium opposite said printing surface, said material being a material which changes to a dark and viewable color upon the application of heat at a pixel position thereof by the thermal printhead of the facsimile machine whereby addressee information can be printed on said covering medium and viewed without removing said covering medium from said printing medium, said coating of a heat-activated material being disposed along strips adjacent two side edges of said covering medium and said coating of a heat-activated material and said coating of a heat-transferrable ink being of substantially the same thickness whereby the printing medium rolls evenly into a supply roll.

7. The printing media of claim 1 characterized in that:
said obscuring portion further includes means for creating an interference pattern over said printing surface rendering images on said printing surface viewed in combination with said interference pattern unreadable to at least a casual observer.

8. The printing media of claim 7 characterized in that:
said interference pattern comprises a pattern printed on a surface of said covering medium.