US2425742A - Electrosensitive recording blank - Google Patents

Description

Aug. 19, 1947.

l7 l8 I9 ACTIVE LAYI'ER 0F- MARKING MATERIAL ELECTROSENSITIVE RECORDING BLANK B. L. KLlNE Filed July 29, 1942 INVENTOR I TEL B. L. KLINE ATTORNEY Patented Aug. 19, 1947 UNITED STATES PATENT OFFICE ELECTROSENSITIVE RECORDING BLANK Application July 29, 1942, Serial No. 452,689

9 Claims.

This invention relates generally to an electrosensitive recording blank, and more particularly to a recording blank on which various kinds of subject matter may be recorded by means of telegraph facsimile or other types'of electrical Signals which are applied to selected elemental areas of the recording blank by means of an electrode that scans the surface of the blank for applyin the signals to selected areas thereof.

Various methods of recording in facsimile by means of electrical signals and other marking agents, and various types or recording mediums, have heretoforebeen proposed, but in general the prior art methods and. recording blanks employed required special handling or treatment prior to their use, as in the case where wet or other electrolytical recording papers were employed or required heaters or other mechanisms controlled by signals which in turn operated to mark the message sheet, or required special handling or development treatment after recording. None of the recordin mediums of the prior art have enabled satisfactory recording to proceed at a sufliciently fast rate with relatively small amounts of marking energy whereby they are adapted for use with the currents and voltages ordinarily employed in telegraph recording systems, and none of the prior art methods and recording mediums have produced the sharp definition desired in facsimile recording consistent with producing records which may be scanned at a higher rate of speed and with small values of currents and voltages.

For example, it is old to have paper impregnated with electrically conducting solutions, or

electrolytes, said solutions being adapted to be decomposed by signal impulses so that a record of the signals is made, and it is old to cause an electric arc to burn holes in a paper recording blank, the holes thus burned representing telegraphic signals or comprising the outline of the subject matter desired to be recorded. Such recordings, however, are only suitable for relatively coarse work where no fine gradations of tonal values are necessary, such as in the reception of telegraphic signals in general and recording of various types of curves in connection with the performance of instruments. However, in the transmission of matter, particularly of pictures and the like, where half-tones are encountered, the range of tonal values extends from what might be termed pure white to pure black.

Prior art methods ofrecordin have sufi'ered from the serious draw back of diffusion of the record area. Thus, for example, with the electrolytic paper method previously discussed, the capillary action of the paper often results in a spreading of the record element so that satisfactory definition for precise work becomes an impossibility under normal high speed operation. Also,

whererecording is effected by means of holes burned through a paper blank by the action of an arc discharge, it will be appreciated that the result would not produce fine definition and can produce no fine gradations or tonal values of the recorded subject matter; moreover, the disadvantages of having a record sheet with holes burned through the sheet will be obvious, and there is also an appreciable fire hazard involved in such a method of recording.

This invention provides a recording blank, and enables a method of recording to be used, which isremarkably free from the above objections. For example, high speed of facsimile recording is a prime requisite due to the customary diversion from other commercial services of the telegraph transmittingmeans in connection therewith. The need of high speed operation is further enhanced by requirements for sharp definition. Thus; in picture transmission, increasing the number of lines to the inch increases the length of time required for the marking of a record and, therefore, places a slow speed system at a further disadvantage. A further anddesirable property of the recordin accordance with the present invention is the: fact that the recording blanks may be stored under normal conditions for long periods of time without any substantial deterioration and are readyfor use at all times. No supplementary development or other treatment of the recording blank is necessary apart from the reception of the signal impulses and the transformation of such signal impulses to record elements during the normal process of recording. The blank is a dr blank which operates in the absence of moisture; it is capable of recording at an extremely-fast rate andwith very sharpdefi-nition; it does not require special handling"; is not adversely afiected by exposure to light or air; and is adapted for use with recording apparatus of a comparatively simple character.

The invention in general makes use of the phenomenon of the reduction or conversion of a chemical compound, when an electrical signaling potential or current is applied thereto, to form another compound which distinctively differs in appearance from the former compound, and to a varying degree depending upon the varying values of the signaling potentials or currents employed. The compound to be thus reduced orconverted preferably, although not necessarily, is disposed in a suitable vehicle as a thin adherentcoating or applied as a pigment .or lacquer to a conductmg base material which for. practical purposes may be consideredas permanent and uninfluenced by the electrical currents or potentials, and which functions as one electrode surface forlthe entirerecordcoating. a

An object of the invention'is an electrosensitive recording blank in which the foregoing disadYeIL.

tages of the prior art methods are obviated, and which produces sharp definition of the recorded image and various gradations and tonal values, with a relatively small expenditure of electrical marking energy, and in which marking may proceed at a high rate of speed and the marking energy confined to sharply defined areas beneath the recording stylus at any given instant durin the scanning operation.

Another object is an improved recording blank embodying a marking compound which is generally light in color to provide a desired light background for the blank, and which readily is reduced or converted to a black or dark colored compound by the application thereto of electrical marking potentials or currents to produce the desired recording effects, and without requiring a metathetioal reaction between two different compounds.

A further object of the invention is a recording blank of the character disclosed which is dry and capable of recording in the absence of moisture, and is substantially unaffected by ordinary conditions of humidity, temperature and heat, and in which complete recording may be effected with a blank in the same dry state as when it was made.

Other objects and advantages of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawings, in which:

Fig. 1 illustrates diagrammatically a facsimile system embodying transmitting and recording means, the said system being of the type embodying a receiver in which a telegraphic blank embodying the present invention is adapted to be used; and

Fig. 2 is a perspective view of one form of receiving blank embodying the present invention.

Referring to Fig. 1 of the drawings, there is shown a transmitter T comprising a rotatable metallic cylinder 12 supported by a driving shaft I3 which is journaled in a suitable manner in the frame members [4 and 15. Durin transmission of signals, the cylinder is rotated in th direction indicated by the arrow by suitable means such as the motor Hi. The latter may conveniently be of the alternating current synchronous type and is connected by a driving pu11ey I! and the belt I8 to the driven pulley I9 secured for rotation with the shaft l3. Means are provided, as shown, to prevent slippage of the belt on the pulleys.

Transmission is effected by the apparatus illustrated in Fig. 1 in a well known manner, such as described in my Patents No. 2,229,091, issued January 21, 1941, and No, 2,251,742, issued August 5, 1941. Briefly, a scanning electrode or stylus 22, whose point bears on the surface of a blank 1) bearing conductive characters, is supported by a traveling carriage 23 adapted for longitudinal movement. The stylus 22 is caused to traverse the cylinder in a longitudinal direction by means of the rotatable threaded shaft 24, and therefore the stylus point will describe a spiral path as it moves over the surface of the transmitting blank and thus produce a scanning action.

The method of obtaining the scanning movement described above is well known, as are various other methods of scanning a given field, and likewise the action of the receiver R which is to be briefly described and which forms no part of the present invention, is well known. The transmitting apparatus T and the receiving apparatus R may include transmitting and receiving amplifiers A1 and A2 respectively, which are intercom 4 nected by an available communication circuit L. If desired, the transmitted signals may have a carrier frequency component introduced by the transformer 26 which is connected in series with the lead 29 from the transmitting drum I2.

At the receiving end the recording may be accomplished by any apparatus suitable for the purpose. It is to be especially noted that a telegraphic blank produced in accordance with the present invention enables the receiving device to be of an extremely simple nature. The receiver R illustrated by Fig. 1 shows one arrangement for recording upon a recording web or blank w and comprises a rotatable cylinder 3! of substantially the same diameter as the cylinder of the transmitter T. The cylinder 31 is rotated in synchronism with the transmitting cylinder 82 in any suitable manner, as by means of an alternating current synchronous motor 32 or other kind of motor which is kept in step with the transmitting motor 16 by any known method of obtaining synchronism. The receiving blank, which is of the kind embodying the present invention, is secured to the cylinder 3| in any suitable manner so that it may be traversed by the point of the scanning recording stylus 33. The stylus 33 is secured to a carriage 34 mounted on a threaded shaft 35 which is rotated with the cylinder 3!. The threaded shaft in combination with the rotation of the cylinder produces the scanning action of the stylus 33. The incoming signals are repeated and amplified in the amplifier A2 in a manner well known in the art to translate the signals into suitable current impulses of the received image.

It Will be understood that instead of the receiver just described, any other known receiver of a like nature and suitable for the purpose may be used. Also, it is to be noted that the only essential of a suitable receiver is that it shall possess an electrode or stylus similar to the stylus 33 which is capable of applying marking potentials to selected elemental areas of the message blank to cause passage of a marking current through the blank in accordance with incoming signals.

A message blank to embodying the invention in its simplest form is shown in Fig. 2 of the drawings wherein reference numeral 38 represents a sheet of fibrous material such as paper, and applied to the surface of the paper is an adhesive coating or film 31 which comprises a marking substance embodying the principles of the present invention.

In accordance with the instant invention, I have discovered that a large class of substantially water-insoluble organic sulphur bearing compounds of metals is especially suitable for use as the marking coating or film. These compounds, for example, comprise thio-oxalates, thiolates or mercaptides, thiolacetates or thio-glycolates, and thiocarbamides, of metals such as, for example, copper, silver, mercury and lead, and are in general characterized by originally being white or light in color, thus providing a desirable lightcolored background for the recording blank, and when marking potentials 01' currents are applied to or passed through a coating of such compounds in selected elemental areas of the recording blank, the compounds in just those areas are reduced or converted to sulphides of the metals. These sulphides, being black or dark in color, serve to delineate the recorded subject matter, whether it be pictures, writing, drawings, or other subject matter, in sharp distinct contrast with the light colored background of the blank.

Moreover, especially sharp definition of the arcane picture or other subjectinatter' is obtained; and"- the values of the marking potentials or currents necessary to efiect the reaction may be" relatively small. Apparently this is because, this class of metallic salts, the passage of electrical currents less than that Which-Would be' neeessaryto effect disintegratioh and removal or those portions of the coating on Which marking is d's'ird "to b efiected, since the action involves only '8' partial decomposition of the molecules of the" ma ihg material. Moreover, the lila rkin'g rii ayiiu effected at a higher rate since it is not necessary to efi'ect reaction between a plurality of different cumpounds by metathesis; as in the caseof cert n Wet electrolytic blanks or pyro-record ing heretofore known'in' the prior art, and alsb due to the fact that the organic compounds disclosed herein are more readily converted by the action of electric currents than are inorganic compounds. The resulting sulphides produced" are insoluble and permanent in character, and usually are either black or dark colored in appearance.

Preferably, although not necessarily, the foregoing compounds of copper, silver, mercury and lead are employed. Of these compounds, the thi'o-glycolates of copper, silver and lead, the mercaptides of copper, silver, lead and mercury, the thiooxalates'of mercury, and the copper sil ver and mercury compounds of thiocarbarnide have been found especially suitable, since they are all easily formed and may readily be applied to the recording paper, a'ndare converted to black distinct sulphides of these metalsupon theappli-- cation of relativelysrriall signaling potentials to the selected elemental areas of the recording blanks coated or impregnated with such compounds. Moreover, these compounds provide a" very light and pleasing background against-which the recorded s'ubject'rnatter sharply stands out, since they are either White or light yellow in color prior to their conversion by the application of the signaling potentials; Those compounds which are light yellow in ap'pearancernay be used to simulate the ordinary telegraph blank whi'ch usually is of this color, and the white compounds may advantageously be employed for transmitting pictures, photographs and similar subject matter, although the particular compound em} ployed for a particularservicevvillin general be a matter of choice.

The compounds of silver'a're' not as stableas the others, and, under certain circumstances show some tendency to decompose or become darkened if exposedto direct rays of stronglight, and therefore greater care must betaken prior to a recording operation. On the other hand, this characteristic of the silver salts may bedesirable Signaling currents through 95 coating thereof, or

by the application of elect-ricer signaling poten tials to suchcoating, although for economic considerations the foregoing fiietallic compounds specifically mentioned are preferred. There are, however, hundreds or organic sulphur-bearing com ounds, manyof which are capableo'f form ing 1ight=doloredg water insoluble' chmpoun'ds with metals, wnicncoxnpounds'are convertible" to the sulph'ides or the metals in accordance with the present invention", 7

The body 36' of the recording blank may be' made conducting by being impregnated with a suitable el'ec'trolyte'such; for example, as salts of Sodium, potassium and ammonium,- particularly their iodides, Sm nmeyan'ides, bromides, ch10- ride's, nitrates and sulphates; metanitr'obenzehe sulphonicacid; or other electrolytes disclosed No. 2,251,742, issued August 5, 1 941, No. 2,131,533, issued NOVemb'er28, 1939, ahd N0. 2,283,558, isslled May 19,1942. Preferably the elebtrolyte'eih-' ployed is dissolved or suspended in mun-amendmglycol, d'ith ylene e1y'co1, 1-bpy1ene glychl, or but'yle'ne' glycol, disclosed in the aforesaid Patent- No; 2,229,091} or in solid aliphatic orarorn-atic alcohols or other suitable solidoxygen containingsolvent, suchas disclosed in the aforesaid Patent No, 2,283,558; or the bo'dy of the blank may have incorporated therein finely divided serum or me: tallic powders of silver, aluminum, copper, brass; etc, which-particles are homog neousl di's'pbs'ed' throughout the" sheet to render thesarn c'or iducting'. The particles' of carbon cement-may he incorporated in thepul'p from which the paper is made so that the paper isilihf'ehtly a relatively g'oodcon'ductor of electricity,- and therefore Wi-ll be suitable foru'sle by merelyapplying' the marking coating to'its surfac'e.

If the a er layer 36 'Of the blmk-i so f aj'kiri d which is not inherentl conductive; it may bedesirable to first apply the filth or coating of the marking substance to its surface and thereafter to impregnate th back of the fialfiir With One Of the electrolytic solutions abevei-ererrea to. either case" the con-ductivebase immediately be"- neath the coating provides a relatively good conducting path directly through the recording blank from the point of the scanning stylus to the recording cylinder Ioeheath the blank, and prevents dispersion of substantial amounts of marking current in and around the area; of the blank beneath the stylus at any given instant'so that the electrical effects are concentrated in just theelemental area being scanned by the stylus, and thus spraying efiects or' other undesirable effects on the coating at this point of the generally in' the manner disclosed in the K line and E 'ngler Patent No. 22251247, issued Decembe! 17, I940.

Inasmuch as the material in the doatihgtobe reduced or converted represents the loadof the electric current, the resistanceof the' recording material should be concentrated that region. In order'to'pro-Vide a permanentrecord, thernark i'rigmaterial or pigment inayb e' suspended" in" a vehicle or binds-r012cenmbseqeri atwe lacquers, nyurdca'rbbn resin's; shellac dissblved in a'l'cbhol,

ester gums, natural varnish gums, polyvinyl resins, etc., and suitable solvents, such as ester sol- Vents, viz., ethyl, butyl and amyl acetates, or butyl lactate and cellosolve, or hydrocarbon solvents, such as isopropyl and ethyl alcohol. The vehicles and binders may also include oils such as linseed, tung, perilla, fish and soya bean. Thinners may comprise turpentine, spirits and esters, such as butyl acetate or butyl lactate, and suitable gums and resins which may be used are natural varnish gums such as kauri, dammar and cumar, and synthetic resins,

The filler or marking compound such as above referred to, is preferably uniformly distributed in finely divided form throughout the binder. The resistance characteristics of the entire mixture may be adjusted either by controlling the resistance characteristics of the binder itself or the filler, although in practic the resistance characteristics of the binder are not easily controlled since such binders ordinarily are insulators when dry. By controlling the fineness of the grains of the filler and the dispersion of this material throughout the binder, it is possible to control the electrical breakdown characteristics of the entire coating within reasonable limits. This coating preferably is applied as a surface covering to the base material and forms therewith a unitary record blank. Inasmuch as the electrical breakdown strength of the entire coating is to be maintained at a uniform value with the variations in reduction or conversion of the marking material being controlled by the intensity of the signalin currents or potentials, the thickness of the coating should be maintained at a substantially constant value throughout the useful area of the record. While the base material itself should have an electrical resistance low in comparison to th resistance of the marking coating which inherently is high, the resistance of the base material may have a substantial value and may vary within a considerable range of values.

The marking substance may conveniently be applied to the surface of the blank as an ink or pigment which is formed by powdering the substance and grinding this powder with a linseed oil or other suitable vehicle to a suitable consistency for application to the surface of the blank by a printing operation, or by grinding in a lacquer or other binder vehicle. It is within the scope of the invention to mix a plurality of selected substances from the class herein disclosed in formulating the ink or other coating mixture. In some cases it may be desirable to incorporate a trace of drier to aid oxidation of the vehicle when in ink form, the powdered marking substance being substantially unaffected in any 'way by the inclusion of a drier. Resinates, linoleates of lead, cobalt, manganese, etc., are standard driers and may be used when a drier is considered desirable or necessary.

In order to facilitate finer definition of the recorded subject matter, and to enable the lower marking potentials and current values to be employed, the marking substance when used as a coating or film is applied as a very thin film, the surface layer preferably being of the order of .00008 to .00015 of an inch. As above stated, the white or light colored sulphur bearing salts are reduced or converted, by the application thereto or passage therethrough of the signaling potentials or currents, to colored metal sulphides, this change in color at the points to which the signaling energy is applied, providing a sharp contrast with the unchanged portions of the coating which have not been affected by the signaling potentials or currents.

The thickness of the coating should be'just sufilcient to mask the base material or supply a good background for the recorded subject matter. The potential applied to the coating may be just below the marking value so that superimposed signal potentials will provide the differential necessary for effective operation. The character of potential appears to be immaterial and recording may be efiected either with direct or alternating currents including frequencies ranging into the carrier spectrum.

Instead of applying a coating to a conducting blank in the manner aforesaid, for certain purposes it may be sufficient to impregnate the recording blank with the marking substance together with the electrolyte or conducting substance, or these compounds may be mixed with the paper pulp during the manufacture of the paper or other material prior to formation of the web of which the blank is composed, although the sharp definition obtainable with the coated form will not in general be obtainable where the blank has thus been impregnated. Such a blank will be suitable where relatively coarse recording is sufficient, or Where still lower power input levels are desired.

Combinations of the foregoing types of materials may be employed, if desired, and two or more coatings of the substances may be employed to provide better covering power which is especially desirable in the case of carbon bearing paper or a blank which is relatively dark in color. It i also possible to add other substances to the marking substances to give them greater covering power or increase the opacity thereof, if desired, such for example as a small amount of titanium dioxide or other pigment which in combination with the marking substance gives the desired covering effect.

It will be appreciated that other compounds may be employed in whole or in part in addition to those specifically mentioned as illustrative examples, which other compounds will be recognized by those skilled in the art as being equivalents for the purpose of the invention, and I therefore do not Wish to be limited except as indicated by the scope of the appended claims.

What is claimed is:

1. An electrosensitive recording blank comprising a sheet having in intimate contact therewith, over the recording surface of the blank, a coating of a recording medium for producing marking effects in selectable elemental areas of said recording surface upon application of an electrical signaling potential to said areas, said recording medium comprising a sulphur-containing organic chemical compound of a metal in an amount sufficient to produce said marking effects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

2. An electrosensitive recording blank comprising a sheet having in intimate contact there- I with, over the recording surface of the blank, a

coating of a recording medium for producing marking effects in selectable elemental areas of said recording surface upon application of an electrical signaling potential to said areas, said recording medium comprising a sulphur-containing organic chemical compound of a metal in an amount sufficient to produce said marking effects, which compound is substantially insoluble in water and initially is light in color and has the property of being convertible by partial decomposition to a dark-colored sulphide of the metal uppon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

3. An electrosensitive recording blank comprising an electrically conductive layer having a recording medium in intimate contact therewith for producing marking effects in selectable elemental areas of the recording surface of the blank upon application of an electrical signaling potential to said areas, said recording medium comprising a sulphur-containing organic chemical compound of a metal in an amount sufiicient to produce said marking efiects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

4. An electrosensitive recording blank comprising an electrically conductive layer having a recording medium in intimate contact therewith for producing marking effects in selectable elemental areas of the recording surface of the blank upon application of an electrical signaling potential to said areas, said recording medium comprising a sulphur-containing organic chemical compound of a metal, for example, copper, silver, mercury and lead, in an amount sufficient to produce said marking effects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

5. An electrosensitive recording blank com prising an electrically conductive layer and a superficial coating of a recording medium directly disposed over said conductive layer as a thin adherent film for producing marking effects in selectable elemental areas of the recording surface of the blank upon application of an electrical signaling potential to said areas, said recording medium comprising a sulphur-containing organic chemical compound of a metal in an amount sufficient to produce said marking effects, which compound is substantially insoluable in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrast ing with the the background of the recording surface of the blank.

6. An electrosensitive recording blank com-' insoluble in water and has the property of being 10 convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

7. An electrosensitive recording blank comprising a sheet having in intimate contact therewith, over the recording surface of the blank, a coating of a recording medium for producing marking effects in selectable elemental areas of said recording surface upon application of an electrical signaling potential to said areas, said recording medium comprising a thio-glycolate of a metal in an amount sufficient to produce said marking effects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

8. An electrosensitive recording blank comprising a sheet having in intimate contact therewith, over the recording surface of the blank, a coating of a recording medium for producing marking effects in selectable elemental areas of said recording surface upon application of an electrical signaling potential to said areas, said recording medium comprising a thiocarbamide of a metal in an amount sufficient to produce said marking effects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

9. An electrosensitive recording blank comprising a sheet having in intimate contact therewith, over the recording surface of the blank, a coating of a recording medium for producing marking effects in selectable elemental areas of said recording surface upon application of an electrical signaling potential to said areas, said recording medium comprising a thio-oxalate of a metal in an amount sufficient to produce said marking eifects, which compound is substantially insoluble in water and has the property of being convertible by partial decomposition to a sulphide of the metal upon application of an electrical potential to said compound, thereby to form a colored mark contrasting with the background of the recording surface of the blank.

BERNARD L. KLINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,844,199 Bicknell et al Feb. 9, 1932 1,880,449 Hickman et a1. Oct. 4, 1932 2,038,486 Glas Apr. 21, 1936 2,181,533 Kline et al. Nov. 28, 1938 2,229,091 Kline Jan. 21, 1941 2,306,471 Solomon Dec. 29, 1942 FOREIGN PATENTS Number Country Date 329,258 Great Britain May 15, 1930 388,724 Germany Jan. 19, 1924 523,258 Germany Apr. 21, 1931

Images