US2661998A - Electric marking method, apparatus, and carrier for facsimile systems and the like - Google Patents

Description

Dec. 8, I953 L. PESSEL 2,661,998 ELECTRIC MARKING METHOD, APPARATUS, AND CARRIER FOR FACSIMILE SYSTEMS AND THE LIKE Filed April so, 1949 INVENTOR LEUPDLD PEssEL ATTORNEY Patented Dec. 8, 1953 ELECTRIC MARKING METHOD, APPARATUS, AND CARRIER FOR FACSIMILE SYSTEMS AND THE LIKE Leopold Pessel, Springfield Township, Montgomery County, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application April 30, 1949, Serial No. 90,756

16 Claims.

This invention relates to electric marking, and particularly to that type of marking in which desired indicia are produced or reproduced on a specially prepared carrier element, in a manner suitable for facsimile systems or the like.

Many techniques have been developed in the past for producing marks by means of an electric current. An appreciable need for such tech-- niques has been experienced in the facsimile art where images are transmitted from one place to another as a sequence of electrical signals and the image is reproduced in more or less permanent form on a carrier at the place of reception from the electrical signals that are received. However, practical techniques developed up to now were subject to one or more of several serious disadvantages. Either the mechanism or material used for marking a carrier was gradually consumed, requiring periodic attention, or he apparatus required periodic addition of chemi cals to sensitize the carrier for marking, or a presensitized carrier had a short life.

Many of these difiiculties result from the passage of electric marking current through the carrier. In the so-called wet marking processes the electric signals are passed through the car" rier as an electrolytic current to produce electrolytic marking effects. For such processes, the carrier is generally moistened just before marking, and a supply of moistening liquid, as well as marking chemicals in many cases is always needed. Where a so-called dry marking process is used, th passage of current through the carrier produces chemical or physical changes that are accompanied by erosion of a marking elec trode that contacts the carrier. Other marking methods are either not practical or involve the same disadvantages as those described or have other disadvantages equally undesirable.

Among the objects of the present invention is the provision of improved marking carriers as well as methods and apparatus for making them, in which these disadvantages are avoided.

A further object of the invention is the provision of improved marking methods, apparatus and carriers in which electric marking is effected without passing the electric marking signal through the carrier to be marked, thereby simplifying the techinque.

The above as well as other objects of the invention will be more readily understood from the following description of exemplifications thereof, reference being made to the accompanying drawings wherein:

Figure 1 is a schematic showing of the essen- 2 tial elements of one form of marking apparatus embodying the invention; and

Figure 2 is a plan view of another form of marking apparatus exemplifying the invention.

According to the present invention marks are made by providing a carrier with a surface coating that locally changes its appearance where ultrasonic compressional vibrations are impressed on it, and then impressing on portions of this surface such ultrasonic vibrations to produce changes in appearance corresponding to the desired indicia. A section of the surface may be scanned to reproduce indicia corresponding to a desired image.

The carrier may be a sheet, web, band or tape of self-supporting material such as paper or other interfelted fibrous article, cast, molded or extruded resin as regenerated cellulose for example, as well as textiles or the like. Surface coatings that change in appearance are those that respond to the thermal, chemical, mechanical effects of the compressional vibrations or to any combination of these effects.

By ultrasonic compressional vibrations, there is intended compressional vibrations having frequencies of at least about 20,000 cycles per second, beyond the limit of audibility.

One example of a suitable surface coating is a stratum containing a finely-divided metal acetylide. These acetylides are normally white or relatively light-colored, but when subjected to compressional vibrations of ultrasonic frequencies, readily decompose, liberating finely-divided carbon which is quite black, as well as finelydivided metal also black in appearance. Copper, silver or mercury acetylides are highly satisfactory but any aoetylide of a metal in the B families of groups 1, 2, 3, 4 and 5 in the periodic system, can be used. Such acetylides being well known in the art, a complete description of their properties and methods of preparation are not given here, but can be obtained from the reported literature. Reference is specifically made to The Chemistry of Acetylene, a text written by J. A. Niewland and R. R. Vogt, and copyrighted 1945 by the Reinhold Publishing Company, Chapter II (pages 40-70) of which describes many acetylides as well as processes for their preparation.

The acetylides are fairly stable in the absence of mechanical shock and when kept away from elevated temperatures. The original light appearance can accordingly be preserved indefinite- 1y. Where the appearance is locally changed by the ultrasonic vibration, the deep black color has at least the permanency of carbon, a goal not often reached in marking compositions.

The acetylide is prepared as a coating by persing it in finely-divided form the su c of a self-supporting carrier. To assure the Z'":- striction of any desired to local areas subjected to ultrasonic vibre .on, the dispersed acetylide is diluted with relatively inert materials such as starch, casein, powdered talc, pot dered silica, etc. If this is not done, the more readily decomposable acetylides, if present a relatively heavy coating, wou ave a tendency to decompose explosively, spree. mark formation beyond the area intended to be marked. extent of dilution can be varied widely. A final marking coating having about 56 percent acetylide by Weight is highly effective although as little as 10 percent, and as much as 96 percent acetylide, suitable. Where the acetylide is incorporated in the carrier surface, by appli The dilution also simp fies gradation of the intensity of mark by varying the ultrasonic energy impressed on the coating. Thus all or substantially all of the acetylide particles will not be decomposed until the ultrasonic energy, impressed on a coating carrying these particles, reaches a relatively high magnitude. As the energy intensity decreases, more and more of the particles are left undecomposcd, as by reason of small thicknesses of the coating interposed between the particles and the ultrasonically vibrating marking structure. The marks can accordingly be so made as to more faithfully reproduce the full range of desired intensity gradations, as in ordinary picture scenes, in addition to the high contrast of black line images such as printed matter or drawings.

The acetylide or acetylide-containing particles are applied as a coating to the self-supporting carrier by bonding agents which may be mixed with the particles and applied together with them, or by embedding the particle in the carrier surface itself. Thus any of the conventional papercoating techniques can be used to spread over the surface of a paper sheet, a coating mixture of the particles with casein, starch, or resin bonding in- .i;

'gredients in a liquid vehicle. The bonding ingredients themselves may provide all the acetylide dilution that is needed. Alternatively the marking particles can be applied to the paper as it is being formed on a paper-making machine. In the Fourdrinier type of paper-making apparatus, where a slurry of paper-making fibers is poured on a moving fine-mesh wire screen which retains the fibers and permits the liquid suspending medium to drain through, the acetylide particles mixed with some binder, can be readily applied to the wet paper web formed on the Fourdrinier Wire, or to the web as it is being dried. The type of bonding ingredients or binder is not limited and suitable examples are the conventional ones including starch, casein, glue, gums, resins such as polyvinyl alcohol, sodium carboxy methyl cellulose and partially polymerized thermosetting or thermoplastic resins capable of later hardening or curing.

The coating, either after or during carrier formation, can also be effected on plastic sheet-s or films. During the film casting, for example, the coating is readily applied before the plastic is completely set or solidified, and will be adherently held in place by the plastic after complete solidification. Where the acetylide is incorporated in the carrier surface, the surface elements of the carrier are mingled with the acetylide particles and act as a diluent.

One elrective coated carrier for use with the invention is a paper sheet coated with a uniform mixture of equal parts by weight of silver or copper acetylide and a 10 percent dispersion of polyvinyl alcohol in water. Marks are readily produced by compressional vibrations at about 26,000 cycles per second, using about a hundred watts per square millimeter of surface subject at any instant to the vibrations. In general about 10 or more watts of compressional vibrations per square millimeter, Will cause the development of the desired marks.

According to a different phase of the invention, marks are readily produced on a carrier having a surface that changes in transparency when subjected to ultrasonic vibrations. Thus a substantially opaque and relatively brittle or friable coating on a carrier is pulverized by the mechanical action of impressed ultrasonic vibrations and thereby at least partially removed exposing the carrier surface otherwise hidden by the coating. The normally hidden surface preferably has an appearance that strongly contrasts with the relatively brittle opaque surface to provide easily distinguished marks.

As an example of this type of carrier, an ordinary black paper containing about 5 to 10 percent of carbon black is coated with a dispersion of T1102 pigment in a, sodium silicate solution binder having a restricted amount of flexibilizing that are powdered by compressional vibrations are pigment-binder mixtures in Which the entire binder is any of the conventional flexible binders but is used in such limited proportions that the coating does not have the conventional flexibility. The casein, starch, gum or resin binders listed above are satisfactory if kept below 10 percent by weight based on the total coating solids.

Instead of using a white hiding coat over a black lower surface, the hiding coat may be black and the lower surface white. Alternatively, a light color such as yellow may be substituted for the white, and/or a dark color such as purple or brown used instead of black.

To produce the desired marks on the carrier prepared by either of the above techniques, an ultrasonically vibrating stylus is held against the carrier surface and moved over the surface so that the resulting change in appearance conforms to the desired indicia. The movement may be manually effected, as Where a writing is being made, or the stylus may be scanned to reproduce a facsimile raster or image.

Figure 1 schematically shows the essential elements of one form of marking apparatus according to the invention. A roll ID of an elongated sheet of carrier to be marked, wound on a mandrcl i2 is unwound and passed over a backing plate M by a pair of feeding pinch rolls l6, l8 which are suitably rotated. The pinch rolls I6, 18 grip the sheet firmly and advance it in the desired manner, either automatically or by manual actuation.

The backing plate I 4 acts to support a marking zone H of the sheet I0 so that ultrasonic vibrations can be impressed on any desired portions of this zone. A marking stylus is mounted for ultrasonic vibration in a transducer holder 22, and electric leads 24, 26 supply th stylus-vibrating energy from an oscillator 28. The transducer 22 may be of the piezo-electric, magneto-dynamic or magnetostrictive type, all of which are well known in the art and need no further description here.

The projecting stylus end 3G is provided with a carrier-contacting surface small enough to limit the instantaneous marking area to the desired fineness thereby effecting substantially any desired degree of resolution. This end is preferably made of hard material as by tipping it with a diamond or by forming it of hardened steel.

In operation, the oscillator 28 is started and the stylus end 30 held against the carrier marking zone I l and moved about over the zone to form the desired marks. Writing can thus be made manually without requiring periodic replacement of a writing tool or marking medium such as The combination makes a highly effective reproducing pantograph when the stylus is connected for following the movement of writing to be reproduced. Stylus actuation for re-- producing may be mechanical as in the conventional pantograph, or electrical in the telautograph. A brushing roller 32 is provided for removing loosened portions of the carrier surface, where the second of the above-described types of marking technique is used. The brush roller rotates and clears away any coating portions that have been loosened but still adhere to the carrier. This brush can be omitted with the first of these types of marking.

The present invention also includes the reproduction of indicia rasters from an original, by scanning a marking zone and applying marks corresponding to the electrical raster generated by scanning an image of the original, as in the facsimile process. It is only necessary to provide a suitable scanning arrangement for the stylus, and coordinate the marking intensity with the scanning. Suitable scanning can be supplied by any convenient system. One such system utilizes an endless cross-thread on a rotating shaft, the stylus being connected by a thread following claw to move along the thread and reciprocate to and fro across the marking zone as the shaft rotates in one direction, as shown in the U. S. patent to Nicolson No. 1,918,124. An alternative system is the sweeping of the marking zone in one direction as a repetition of lines. In either case the carrier is connected to shift longitudinally a small amount with each transverse scanning line so that the successive lines are displaced along the carrier to reproduce the original raster.

Figure 2 is an example of the latter type of facsimile reproduces. Here a framework plate 59 carries a roller feeding system for supplying and moving a recording sheet 59 across a one-way scanning marking mechanism. The sheet is unwound from a lower roll (not shown) on which it is stored in wound. up condition, and passes over a backing roller 52 then a feed roller 54, and onto a take-up reel 55 where it may be wound up. Cooperating with feed roller 54 is a retainer bar 55 rotatably carrying a plurality of (ill engaging rollers, El, 62, 63 and resiliently biased, as by springs not shown, toward roller 54. The sheet '66 is gripped between the roller 54 and the rollers 6!, 62, 63 and is accordingly advanced under the actuating rotation of feed roller 54.

All the rollers, as well as the retainer bar 55, are pivotally held in side supports 58, Hi. The support 10 is exposed to show a feed gear 12 connected, as by a common shaft, to rotate the feed roll 54. The reel 56 may be driven from roller 5 by a conventional slip type linkage, not shown, to automatically wind up the carrier sheet as it it advanced by the feed mechanism.

For actuating the feed gear l2, a motor 15 is mounted below the plate and rotates a vertically extending shaft 78. A gear 89, also underneath the plate 50, is secured to the shaft and is rotated by the motor. A connecting shaft 14 has one end equipped with a suitably shaped gear 34 which meshes with motor gear 80. The other end of connecting shaft M extends up through an opening 32 in the plate 50 and carries a worm 1B for engaging and driving the feed gear 72.

Above the plate 50, the shaft Z3 carries a sprocket 86, and another parallel shaft 19 rotatably carries a second sprocket 8?. Around these sprockets is looped an endless chain 88 which is propelled in cyclical movement around the sprockets by the motor l t. Three ultrasonic vibrators BI, 92, each of which may be of types described in connection with Figure 1, are carried by the chain in approximately equally spaced disposition. This spacing corresponds to the width of the sheet 683 which is devoted to marking.

As so arranged, the chain in its movement which may for example be generally clockwise as indicated by the arrow, will cause the vibrators to succesively scan across an adjacent sec tion of the sheet. Vibrator 9! is shown at the beginning of a scanning line, and by the time it reaches the end of a scanning line, the next vibrator 92 will have been brought to the beginning position. At the same time the sheet Bil will be advanced by means of connecting shaft "Hi so that the next scanning line will be in position for being scanned by the next vibrator S2. The scanning action thus progresses continuously.

The apparatus of Figure 2 is a modification of that desc'ibed in U. S. patent numbered 2,374,673, granted May 1, 1945. Reference may be made to this patent for further details, such as the synchronization of the scanning, that form no part of the present invention.

Electrical connection for the energization of the vibrators 91, 92, 93 is provided by means of the common chassis assemblage including plate 50 as a ground or signal return, and a hot lead in the form of a conductive strip insulated from the chassis and frictionally engaged by a corresponding contact on the respective vibrators. The conductive strip 95 may extend as an endless loop alongside the chain 38 as shown in Figure 2, or it may be confined to a zone opposite the scanning stroke so that the vibrators are deenergized when not actually needed for marking. Alternatively, the strip 95 may to the same effect be continued as an endless loop, only the scanning portion of which is conductive.

Where acetylides are used as described above, the carrier may be impregnated with materials such as ammonium sulfamate or ammonium phosphate to reduce its flammability or rate of combustion. This will have the effect of offsetting any increase in ccmbustibility that may be imparted to the carrier by reason of the presence of the acetylides. For this purpose the fiai mability reducing treatment may be effected at any time, even after the marking is completed. Acetylides will generally remain in undecomposed condition on the marked carrier, as for example in the unmarked portions, so that it may be desirable to safeguard the storage of records prepared by such marking.

Although frequencies of about 20,000 cycles or more have been given above as examples of those at which compressional vibrations are used in accordance with the invention, there appears to be no upper frequency limit, and vibrations of a million cycles per second or even higher are suitable.

While several exemplifications of the invention have been indicated and described above, it will be apparent to those skilled in the art that other modifications may be made without departing from the scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to ultrasonic compressional vibrations, subjecting diminutive portions of said surface stratum to ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

2. The method as defined by claim 1 in which the surface stratum is a coating on the carrier.

3. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to the heating effects of impressed ultrasonic vibrations, and subjecting diminutive portions of said surface stratum to ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

4. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that undergoes a local change r in appearance when subjected to the mechanical effects of impressed ultrasonic vibrations, and subjecting diminutive portions of said surface stratum to ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

5. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to the chemical effects of impressed ultrasonic vibrations, and subjecting diminutive portions of said surface stratum to ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

6. In a method of marking indicia on a carrier element, the. steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to ultrasonic compressional vibrations, said surface stratum including a compound that undergoes a color change when subjected to an elevated temperature, and subjecting diminutive portions of said surface stratum to said ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

7. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to ultrasonic com pressional vibrations, said surface stratum including a compound that undergoes a color change when subjected to mechanical shock, and subjecting diminutive portions of said surface stratum to said ultrasonic compressional vibrations to produce marks corresponding to said change in appearance and to provide a sequence of marks corresponding to the desired indicia.

8. The method as defined by claim 6 in which the temperature sensitive compound is an acetylide that decomposes to liberate free carbon.

9. In a method of marking indicia on a carrier element, the steps of providing a carrier with a surface stratum that changes its hiding power when subjected to ultrasonic compressional vibrations, and subjecting diminutive portions of said surface stratum to said ultrasonic compressional vibrations to produce local changes in appearance corresponding to the desired indicia.

10. The method as defined by claim 9 in which said surface stratum is substantially opaque, but is at least partially removed when subjected to ultrasonic vibrations, and underneath the surface stratum the carrier presents a second stratum of contrasting appearance with respect to the surface stratum for exposure under said partially removed condition.

11. In a method of marking indicia on a carrier, the steps of providing a carrier with a surface stratum that undergoes a local change in appearance when subjected to ultrasonic compressional vibrations, subjecting diminutive portions of said surface stratum to said ultrasonic compressional vibrations to produce marks corresponding to said change in appearance, scanning a portion of said surface stratum with said ultrasonic compressional vibrations, and modulating said vibrations to produce marks having gradations corresponding to the desired indicia.

12, In a marking apparatus for marking indicia on a carrier; support structure; holding elements for holding against said support structure a carrier member the surface of which undergoes a local change in appearance when subjected to ultrasonic compressional vibration; an ultrasonic vibration structure including an exposed diminutive vibratable portion connected to vibrate at an ultrasonic frequency, to engage a correspondingly diminutive portion of the surface of a carrier held against said support structure for producing a corresponding mark, and connected to move across said surface to provide a sequence of marks corresponding to the desired indicia.

13. The combination as defined by claim 12 in which the ultrasonic vibration structure includes scanning means connected to said vibratable portion to cause said portion to scan a section of the surface of the carrier held against said support, and modulation means also connected to said vibratable portion to modulate the vibration intensity to produce a group of marks having intensity gradations corresponding to a predetermined signal sequence.

14. A markable carrier for marking without consuming other marking materials, said carrier including a self-supporting member having a surface, and a surface coating on said surface, said surface coating having hiding characteristics which are altered by the application of ultrasonic compressional vibrations to change the external appearance of said surface and thereby develop marks, said surface and said surface coating being of contrasting appearance, and said surface coating including a hiding pigment and a flexible binder in an amount low enough to make the coating brittle.

15. The combination as defined by claim 14 in which the binder content of the coating is not more than about 10 percent by Weight.

16. A markable carrier for marking without consuming separate marking materials, said carrier including: a paper sheet having a surface,

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,765,983 Mayer et a1 June 24, 1930 2,299,693 Green Oct. 20, 1942 2,317,436 Boller et a1 Apr. 22, 1943 2,317,789 Marriott Apr. 27, 1943 2,444,327 Baldwin June 29, 1948

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