US2263592A - Photoelectric facsimile transmitter - Google Patents

Description

NOV. 25, 1941. i -rs 2,263,592 v PHOTOELECTRIC FAdsIMILE TRANSMITTER Filed March 13; 1939 6 Sheets-Sheet l INVENTOR. LOUIS M. PoTTs A ORNEY.

Nov. 25, 1941. I L. M. POTTS PHOTOELECTRIC FQCSIMILE TRANSMITTER Filed March 13, 1939 6 Sheets-Sheet 2 INVENTORY LOUIS M. POTTS Nov. 25, 1941, I P TT 2,263,592

PHOT OELEGTRIC FACSIMILE TRANSMITTER Filed March 13, '1959 6 Sheets-Sheet :5

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Nov. 25, 1941. po 'rs 2,263,592

HOTOELECTRIC FACSIMILE TRANSMITTER Filed March 13, 1959 v 6 Sheets-Sheet 4 FIG. l6

INVENT OR. LOUIS M. POTTS ATTORNE Nov 25, 1941. M. POTTS PHOTOELECTRIC FACSIMILE TRANSMITTER FiledMarch 13, 1939 6 Sheets-Sheet 5 www INVENTOR.

LOUIS M. POTTS A ORNEY.

Nov. 25, 1941. POT-rs v 2,263,592

PHOTOELECTRIC FAGSIMILE TRANSMITTER Filed March 13, 1939 6 Sheets-Sheet 6 INVENTOR. LOUIS M. POTTS A ORNEY.

Patented Nov. 25, 1941 PHOTOELECTRIC FACSIMILE TRAN SMITTER.

Louis M. Potts, Evanston, Ill., assignor to Teletype Corporation, Chicago, 11]., a corporation of Delaware Application March 13, 1939, Serial No. 261,418

54 Claims.

This invention pertains to transmitters and particularly to a facsimile transmitter in which the transmission of facsimile signals is controlled through a photoelectric system.

In telegraph systems involving apparatus for recording characters by a, series of elemental areas of positive and negative surfaces, transmitting apparatus has been employed wherein each letter, symbol, or character is scanned or analyzed into a succession of constituent areas. In

accordance with such scanned or analyzed areas,

electrical impulses are generated which cause corresponding operation of recording apparatus of the form disclosed in U. S. Patent No 2,000,-

083, issued May 7, 1935, to form the characters tion, there is provided a keyboard-controlled photoelectric transmitter for facsimile telegra phy which comprises a cylindrical screen having rows of apertures (or opaque and transparent portions) and rotatable within a cylindrical housing having a longitudinal row of holes adapted to be uncovered by the alignment of apertures in a plurality of permutationbars controlled by the keys so that a photoelectric cell is activated by a light source to transmit impulses.

More specifically, instead of providing in a facsimile transmitter, a plurality of transmitting discs wherein the periphery of each disc is so cut that it corresponds to a different character to be transmitted, the present invention provides a scanning cylinder or screen having a plurality of circumferential rows of holes, in which each row is analogous in function to a transmitting disc of the transmitter shown in the aforementioned patent. The arrangement of the holes in each circumferential row corresponds to the manner in which the periphery of the corresponding disc in the disc-type transmitter is out. In the disctype of transmitter, the scanning or sensing'of the disc is accomplished by a contact lever individual to each disc, while in the photoelectric transmitter .the sensing or scanning is accomaligned holes in a series of permutation bars onto a photoelectric cell rotated within the cylinder. In the disc-type, the scanning contact lever associated with each disc is selected by a series of permutation bars, the occurrence of an alignment of notches permitting one arm of said lever to fall thereinto, thus causing said lever to rotate into contactual engagement with the disc. In the photoelectric transmitter, the permutation bars comprise a series of thin plates arranged in laminated manner, the thin plates being provided with holes which, when aligned, permit a beam of light to be directed therethrough. Instead of having code notches on the edges, th( se permutation plates are each provided with a row of holes corresponding to said notches, whereby for each permutative setting of the plate (by means of key levers or tape controlled levers) an alignment of holes will result opposite the selected circumferential row of holes in the scanning cylinder, through which the beam of light is permitted to pass to impinge upon the photoelectric cell. As the scanning cylinder makes one complete rotation a series of marking and spacing impulses corresponding to the particular arrangement of holes in the selected circumferential row is transmitted, under the control of the photoelectric cell, over the signal line or channel to operate afacsimile printer.

Another feature of the invention consists in providing a keyboard transmitter wherein the hole opposite the row of apertures to be sensed or scanned is uncovered by a shutter controlled by the keys of the keyboard so that the photoelectric cell is activated by the beam of light projected through the uncovered hole.

According to another feature of the invention light is conducted or transmitted from a single concentrated source through a series of quartz rods extending from the scanning holes' opposite the circumferential row of holes to be scanned to a photoelectric source.

A fuller understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a top view of the keyboard-type of photoelectric facsimile transmitter provided with a permutation slide shutter;

Fig. 2 is a fragmentary perspective view of the permutation-slide arrangement;

Fig. 2 is a front elevational viewof the apparatus shown in Fig. 1 with parts broken away to plished by directing a beam of light through the show more clearly the details thereof.

Fig. 4 is a sectional view taken on line i-l of Fig. 3; I

Fig. 5-is a sectional view taken on line 5--5 of Fig. 3;

Fig. 6 is a perspective view of the photoelectric cell and its housing;

' Fig. 7 is a sectional view of the photoelectric cell and housing therefor;

Fig. 8 is a development of the scanning cylinder or light chopper wherein the apertures are etched in a metallic plate, and is a view of the inside of the unfolded cylinder, cut for unfoldment along the line AA of Fig. 15;

Figs. 9, 10, 11, and 12 are fragmentary views of Fig. 13 is a schematic diagram of the electrical the present embodiment, selector mechanism |5 comprises six pairs ofcode bars l6 and I1, each their free ends formed with oppositely offset lugs,

which are disposed on opposite sides of the pivot rod 2| and are spaced some distance therefrom. One of the lugs of each rocker lever projects forwardly into a notch on the edge of the associated circuit at the transmitting station employing the through the circumferential row (developed along line |5-|5 of Fig. 8) corresponding to the character illustrated in Fig. 14;

Fig. 16 is a plan view of a tape sensing mechanism adapted to control the facsimile transmitter similar to the one shown in Fig. 1;

Fig. 17 is an elevational view of the apparatus shown in Fig. 16;

Fig. 18 is a'representation of a portion of perforated tape;

Fig. 19 is a fragmental view of a modified form of keyboard photoelectric facsimile transmitter substituting individual shutters for the permutation bars;

Fig.20 is a partial elevational view of the. embodiment shown in Fig. 19;

Fig. 21 is a sectional view taken on line 2 |2| of Fig. 20;

Fig. 22 is a cross-sectional view of a further embodiment of the invention utilizing a concentrated beam of light;

Fig. 23 is a sectional view taken on line 23-23 of Fig. 22;

Fig. 24 is a sectional view taken on line 24-24 of Fig. 23;

Fig. 25 is a fragmental perspective view of an alternate form of mirror or reflector;

Fig. 26 is a schematic diagram of the electrical circuit at the transmitting station when the scanning cylinder according to Fig. 11 is ,employed, and

Fig. 27 is an enlarged sectionalview taken on line 2'|2'| of Fig. 3.

Having reference to Figs. 1 to 7 inclusive, which show one of the embodiments of the invention, the transmitting apparatus comprises a base portion N (Fig. 1) having at its forward part a bank of keys I2, arranged in the usual manner. Each of the keys i2 is carried on a key lever l3 all of which are pivotally mounted on a common pivot rod l4 supported at the rear of the base portion ll. As is the usual practice, key levers |3 are biased upwardly by individual springs (not shown). Arranged below the key levers l3 and disposed transversely thereof is a permutation selector mechanism indicated generally as l5 (Figs. 3 and 4). Selector mechanism i5 is of the form shown in U. S. Patent No.

code bar i6, and its companion lug projects rearwardly beneath the companion code bar With this arrangement, the depression of either code bar of the pair of bars 5 and I7 rocks the levers i8 and lifts the companion code bar. To the depending portions of the T-shaped rocker levers I8 is articulated a longitudinally movable permutation bar 22. Thus, when the code bars i6 and i! are moved vertically in accordance with the depression of a key lever l3, the permutation bar 22 individual to a pair of bars l6 and I1 is moved longitudinally.

Secured to each of the permutation bars 22 and vertically supported therefrom is a forked member 23. Articulated to each member 23 is a depending arm of a lever 24 pivoted on a common shaft 25. In this manner, levers 24 are articulated to the permutation bars 22 and are adapted to be rocked about pivot shaft 25 to either of two positions. Each of the levers 24 has its vertical arm articulated to a slide member 26. Slide members 26 are slidably supported at 21 and 28. The slides 26 are each provided at the left end thereof with a vertical lug 29 carrying at its free end a stud 3|. Each of the studs 3| (Fig. 2) is connected to one of a series of thin flat permutation plates 32 corresponding in number to the numbers of slides 26, namely six in the present disclosure. Each of the slides 26 is provided at the right end thereof (as viewed in Fig. 3) with a vertically directed lug 33. Cooperating with lugs 33 is a locking bail 34 pivotally carried on pivots 35 and 36 (Figs. 1 and 3) supported in bracket 31. Locking loop 34 also is provided with an integral laterally extending arm 38 (Fig. 1) which carries at its outer end a cam follower roller 39 which cooperates with a cam 4| carried on a shaft According to the operation of the device so far described, the depression of a key lever 3 sets the code bars l6 and H permutably in their upper or lower positions according to the permutation code represented by the key lever depressed. This setting of the code bars l6 and I1 is transferred through the rocker levers Hi to the permutation bars 22, thus setting the bars 22 in their rightward or leftward position. This 'setting is transmitted by levers 24 to slides 26 which in turn set the permutation slides 32 in their rightward or leftward positions. When the slides 26 are so set, the cam 4| operates in proper timed relation to permit bail 34, through follower 39, to rotate counterclockwise to lock the slides 26 through the instrumentality of their locking elements 33.

Located below the key levers l3 and operated thereby is a universal release bail 43 (Fig. 4) pivotally supported at each end by pivots 44. Fixed to bail 43 is an arm 45 which has pivoted at its extremity a trip member 46. Trip arm 46 terminates in' a shoulder 47 which cooperates with the pointed end formed on the depending arm 48 of a bell cranklever 49 pivoted at to a bracket 52 mounted on the base portion Arm 53 of bell crank 49 cooperates with arm 54 of a stop lever 55 pivotally carried on bracket 31. The vertical arm of lever 55 terminates in a shoulder 56 which cooperates with a projection 51 on a stop disc 58 carried on shaft 42. i

Upon depression of a key lever l3, universal bail 43 is actuated in a. counterclockwise direction to impart, through arm 45, leftward movement to arm 46 (Fig. 4). Arm 46, through its shoulder 41, actuates bell crank 49 in a clockwise direction to impart counterclockwise rotation to 'stop lever 55. Arm 46 is provided with a cam portion 59 which coacts with an eccentric screw head 6l-so that in its leftward movement arm 46 is automatically disengaged from lever arm 48. A spring 62 normally biases the arm 46 against the screw head 6|. counterclockwise rotation of lever 55 permits the release of disc 58 and rotation of shaft 42.

Disc 58 is integral with a sleeve 63 loosely carried on shaft 42. I pair of projections 64 which cooperate with corresponding notches 65 in a sleeve 66 secured to shaft 42. Compressed between flanges on sleeves 66 and is a spring 61. In this manner sleeve 63 has slidable relation with shaft 42. Also fixed to shaft 42 is a flanged sleeve 68, and positioned between sleeve 63 and sleeve 68 and separated therefrom by friction discs 69 is a gear 1|. Compression spring 61 acts through sleeve 63 to compress or clutch the gear 1| between the friction discs 69, thus providing a friction clutch between the gear 1| and the shaft 42. Gear 1| meshes with a pinion 12 fixed to the shaft 13 of a motor 14. The aforementioned cam 4| is integral with the sleeve 66.

' Shaft 42 is journaled at its right-hand end (as viewed in Fig. 1) in the bracket 31, and at its left-hand end in the housing 8|. Fixed to the left-hand end of shaft 42 is a member 82 arranged to carry or support a scanning cylinder or screen 83, in such a manner that the scanning cylinder or screen 83 is rotatable within the housing 8|.

Positioned within the scanning cylinder 83 is a photoelectric cell 84 (Figs. 3 and 5), comprising a cathode 85 and a pair of anodes 86. As shown in Figs. 6 and '7, the photoelectric cell 84 is contained within a metal cylindrical housing 81 from which'a'wide slit 88 has been cut to correspond to the size or opening of the light apertures, as will presently appear. The right-hand end of cylinder 81 is left uncut and affords a frictional support for the base 89 (Fig. 7) of the photoelectric cell 84. The cylinder 81 is also slit at 9| and 92, so that. the portions of cylinder 81 adjacent the wide slot 88 'may be pressed inwardly so that the photoelectric cell 84 is snugly held within the cylinder. The cylinder 81 is in turn frictionally held in a base portion 93 which is formed at 94 to have a slidable fit in the housing 8| as shown in Fig. 3.

As viewed in Fig. 5, housing 8| is cut off at 95 so as to leave an aperture or slot commensurate in length and width with the slot 88 of the cylinder 81. Adjacent to the face 95 of housing 8| is secured a bar 96, which is provided with an elongated slotted hole 91 commensurate in size with the corresponding holes in cylinder 81 and housing 8|. As shown in Figs. 1, 2, and 3, the slot 91 is further provided 'with a plurality of septums 98 which are spaced so as to provide a series of light confining channels to correspond Sleeve 63 is provided with a and register with the circumferential rows of apertures in the scanning cylinder 83. The function of septums 98 is to prevent light from leaking or escaping from one slot or light confining channel to an adjacent slot. This structure makes possible the use of. a long single-filament lamp for a large number of scanning columns, as well as the use of a long cathode photocell, and is also a factor in dispensing with the optical system. Moreover, this structure increases the parallel nature of the rays striking the scanning cylinder and the photocell. Bar 96 is grooved adjacent to housing 8|; to provide a guide and support for the plurality of permutation plates 32. Interposed between face 95 of housing 8| and bar 96 (as shown. in Fig. 2) is a thin plate 15.

A light source in the form of an incandescent lamp Hill is positioned adjacent the bar 96 on the side thereof opposite to the photoelectric cell 84. The photoelectric cell 84, the slots 88 and 91, the

slot in housing 8| and the lamp I are all arranged on a common center line. The lamp N16 is carried on a suitable bracket 99 mounted on the base portion Suitable electrical connections are, of course, provided for the photoelectric cell 84 and the incandescent lamp I110. The photoelectric cell 84 has a long cathode and a long anode and the lamp I60 has a long filament coextensive with the series of rows of apertures on the scanning cylinder 83.

For purposes of compactness the apertures in plate 15 are arranged in two rows, the apertures 16 and 88 in the upper and lower rows, respectively, being staggered with respect to each other. An aperture 16 is positioned to register with each light confining channel between a pair of septums 98. Apertures l0| in the permutation plates 32 are also arranged in two rows, an apertural position being provided in each row, and

such positions being staggered as in the case of plate 15. However, since there is a position for each aperture, there is not necessarily an aperture in each suchposition, because of the fact that the presence or absence of the apertures in the plurality of plates is determined according to a permutation code. The reason for staggering the apertures in order to achieve compact-ness is that in the permutation plate arrangement there are two selective positions for each plate, so that the slots |0| must move longitudinally of its length a distance somewhat greater than the length of an individual slot, and thus by staggering the apertures, a blank space is provided in plate 15 for the slots |0| when in its unused position.

According to the present invention, then, the plurality of permutation plates 32, instead of being provided with the usual notches in their edges. are provided with apertures llll therethrough which are so spaced that upon movement of the plates permutably, a different series of holes or apertures therein registers for each permutation and admits light there'through which-activates the photoelectric cell 84. This activation of the photoelectric cell 84 is further controlled by the rotating scanning cylinder 83, the apertures in each row, as will presently appear, representing a particular character.

Having reference to Fig. 8, the scanning cylinder 83 is shown developed. Fig. 8 is a development of the scanning cylinder 83 out along line AA in Fig. 15 and unfolded so as to view the developed cyli der in the direction of the arrow H0 in Fig. l and thus to present the inside surface oi the cylinder to view in Fig. 8. Since the cylinder 83 rotates in a counterclockwise direction, as viewed in Fig. 15, it is obvious that the movement of the apertures I02 of Fig. 8 past the openings in the permutation plates 32 is downwardly, and hence this relative motion is indicated by I20 in Fig. 8. Each of the vertical rows of apertures in the development is analogous to a disc I35 shown in the aforementioned Patent No. 2,000,083, the high radii of the scanning disc I35 of said patent being represented in scanning cylinder 83 to the apertures I02. According to one mode of manufacture, the plate used to produce the scanning cylinder 83 is sensitized photographically and the signal symbols represented by the apertures are photographed thereon from a master chart, and through an etching process the apertures I02 are chemically formed or produced by etching completely through the plate. Referring to Figs. 8 and 14, the vertical rows I03 of apertures I02 (Fig. 8) are designed according to a method of prescanning; that is, the character to be transmitted is divided into any desirable number of sending units of area. The several units of each character thus created are assigned to the apertures I02 individual to that character represented by a row I03 in the order of scanning and the dark units of the character shown in Fig. 14 are created under the control of the apertures which admit a beam of light to the photocell to send a signal. In this connection, it is observed in Figl 8 that, because of the staggered relation of the slots or openings I6 and 80 in plate 15 (Fig. 2), the rows I03 in the scanning cylinder 83 are also alternately displaced circumferentially,for the purpose of timing all of the impulses properly. This feature also makes possible the use of the same stop slot I'I (Fig. 2) for both sets of signals. For example, the rows of striations of apertures indicated I8 in Fig, 8 cooperate with the upper row of slots 80 shown in Fig. 2, and the rows or striations of apertures indicated I in Fig. 8 cooperate with the lower row of slots including slots 76 and ii in Fig. 2. The aperture I23 (Fig. 8) for controlling the stop signal, and the stop slots ii in the permutation plates 32 cooperate with the lower slots 16 (Fig. 2). It should be noted that with the form of scanning cylinder shown in Fig. 8, the stop impulse occurs only in one position or row. Thus, if a stop impulse is supplied for each character as in the form of scanning cylinder shown in Fig, 9, the cylinder would be cut substantially in two and would not be sufliciently rigid. Hence, if a metal scanning cylinder is employed, it is considerably stronger when the stop and start impulses are transmitted in one position as shown in Fig. 8.

For an example of prescanning, the letter "R is shown in Fig. 14 together with the blank area between the letter shown and the preceding letter. It is preferred to leave a blank'interval also below the letter so that when the letters are printed in rows one above the other, there will be a space or a white line between the rows. According to the present disclosure, this total areafis divided into 450 units of area, 25 units high and 18 units'wide. It is, of course, understood thatsaid area may be divided into any convenient number of unit areas, depending upon shown in Fig. 15 which is a section of scanning aaeauea cylinder 83 taken substantially on line I-I5 of Fig. 8, the'cross section being taken of the cylinder and not of the flat development.

Scanning begins at the unit I05 (Fig. 14) and progresses vertically to the unit I06, continuing immediately at unit I01, again at unit I08, and again from unit I09 to III, completing the scanning of seventy-eight successive white units, re-

, sulting in the unapertured portion II2 (Fig.

of the scanning cylinder 83. The scanning of 'the black unit extends from unit I I3 to unit I I4 (Fig.

. 14) resulting in the aperture II5 (Fig. 15). Then the three white units I I6 to I I1 result in the unapertured portion I I8, and the twenty-two black units II9 to I2I result in the apertured portion I22 (Figs. 8 and 13). Continuing in like manner, scanning of the total area of Fig. 14 results in the total apertured and unapertured portions or arcs on the edge of the scanning cylinder 83 (Fig. 15). As previously indicated, the section of the scanning cylinder 83 shown in Fig. ,15 represents the letter "R.. Similarly, other cross sections taken through other vertical rows I03 shown in Fig. 8 would represent other characters. Every character code row has the initial starting portion H2. The vertical row in Fig. 8 including the long aperture I23 is the row for the stop signal.

Instead of producing the scanning cylinder 83 from a metal plate, a suitable flexible transparent material, such as a photographic film, may be employed. According to this method a large scale drawing in black'and white may be prepared representing the cylinder in development. Then a photographic copy, positive or negative, as required according to the method of transmission used is reproduced to the exact size desired. Figs. 9 and 10 represent a negative photograph wherein the transparent portions are analogous to the solid portions in Fig. 8. This photographic film is then formed into a cylinder and mounted in substantially the same manner as cylinder 83 shown in Fig. 1. As previously indicated, in the form of scanning cylinder shown in Fig. 9, the stop impulse I24 is embodied in each circumferential row. The arrangement shown in Fig. 9

is especially adapted to transmission with a continually rotating scanning cylinder, wherein it is desirable that the stop condition (exemplified by opaque portion I24, Fig. 10) is a no-light condition, since otherwise special means would be required to illuminate the photoelectric cell continuously when no signals are to be transmitted. Thus according to the method exemplified in Figs. 9 and 10, the scanning cylinder is produced by making the image on a translucent material so that the material will be sufiiciently strong. The electrical circuit employed with the scanning cylinder shown in Figs. 9 and 10 is the same as that illustrated in Fig. 16 of copending application, Se-

rial No. 48,098, filed November 4, 1935 by L. M. Potts, in which event, the marking and spacing light conditions on the photocell are reversed. The noted circuit is similar to the circuit illustrated in Fig. 13 herein, except that the normal grid bias of the electronic tube in the first stage of amplification is changed from a slightly negative condition to a more negative condition, and the photocell has been connected in such a: manner as to bias the grid positively when light falls upon the photocell. In both of said circuits the same effect is obtained upon the tube of the sec- 0nd stage of amplification, so that for marking signals the same kind or nature of signal is transmitted over the line wire. The form of scanning cylinder shown in fragmentary views, Figs. 11 and 12, is also a photographic film. According to this method, instead of making the transparent portions clear, they are made with a series of lines so as to give an alternating current effect. A circuit for this method of scanning is shown in Fig. 26, and will be later described.

Upon each permuted setting of the permutation plates 32, an alignment of holes in said plates will result opposite the circumferential, row of apertures I02 selected, through which the beam of light from the lamp 98 is permitted to pass to impinge upon the photoelectric cell 84. As the scanning cylinder 83 makes one complete rotation, a series of marking and spacing impulses corresponding to the particular arrangement of apertures I02 in the selected circumferential row is transmitted, under the control of the photoelectric cell, over the signal line to operate a facsimile printer.

The type of facsimile printer adapted to be operated from the signals transmitted by the transmitter just described is as shown in U. 8. Patent No. 2,000,083. In Fig. 13 is illustrated a circuit arrangement employed in conjunction with the transmitting apparatus just described. With this circuit arrangement a system is provided in which the plate current is reduced to zero in at least two places in a multi-stage amplifier, so that the on and off conditions are not affected by values of thecontrol light above or below a certain value; that is, the amplifier used with the photoelectric transmitter disclosed has two stages. In the first stage, a certain amount of light cuts off the plate current, and any additional illumination has no effect in altering the final output 'of the amplifier, the current in the second stage being determined by the local adjustment of the circuit. When the light falls below a certain value, sufficient current fiows in the plate circuit of the first electronic tube to reduce the current in the plate circuit of the second electronic tube to zero, and any further degrees of illumination have no effect on the final output.

In the circuit shown in Fig. 13, the photoelectric cell is shown at 84, and as is known, the impingement of light upon the light sensitive cathode 85 causes the emission of electrons therefrom which fiow toward the anode or positive electrode 86 of the photocell. The cathode 85 is supplied with operating voltages from source I34 and changes in the electron stream flowing within the cell due to the varying light intensities falling thereon, will cause varying potential differences to be setup across a resistance I35 which is connected in series with the photocell electrodes. The resistance I35 is also connected to the grid circuit of a multi-electrode electronic tube I36, having a cathode I31 and a control grid I38. The resistance I35 and the cathode I31 may be so connected to the source I34 as to provide a normal grid biasing source I39. The cathode I31 is of the hot cathode type and is heated by a filament I4I connected to a source of current I42, for example, the secondary circuit of a transformer I40. As 'thus far described, the circuit comprising source of current I34, photocell 84, and resistance I35, is the' source or input circuit for the grid control circuit comprising grid I30, cathode I31, conductor I43, biasing source I39, and resistance I35. The plate circuit of electronic tube I38 includes the portion of potentiometer for I34 included between taps I44 and I45, conductor I43, cathode I31, plate I46, resistance I41, and conductor/I48,

and is the source or input'circuit for the grid control circuit of a second electronic tube I49 comprising a grid I5I, cathode I52, and a plate I53. The control circuit for grid I'5I includes portion of source I34 included between taps I45 and I54, conductor I 48, resistance I41, grid I5I, cathode I52, and conductor I55. The plate circuit of tube I49 extends from portion of source I34 between taps I54 and I58, conductor I55, cathode I52, plate I53, thence through winding of line relay I51, through variable resistance I60 and back to source I34. Variable resistance I80 is provided to control the plate circuit of the .tube I49. Cathode I52 is heated by a filament I61 which, like filament I4I, may be connected to the secondary of transformer I40. The current for the exciter lamp I00 may also be derived from a secondary of transformer I40.

Apertures I02 in the scanning cylinder 83 are indicative of marking signals, and the presentment of an aperture into the scanning region will permit the impingement of the light beam upon the cathode of the photocell 84. The condition of the transmitting apparatus, for example, that-shown in Figs. 1, 3, and 4, during cessation of transmission of signals is such that the aperture I23 permits light to pass onto the oathode 8-5 of photocell 84. This is possible because the apertures in plates 32 associated with the stop aperture I23 are of such length that no matter what their selective position may be there is always an opening 11 (Fig. 2) to permit light to pass through the aperture I23 for the stop impulse. Therefore, the scanning cylinder 83, through its row including aperture I23, exercises sole control over the passage of light through the permutation plates 32 at the stop impulse position. Therefore, during the 'stop period, the light from the lamp I00 passes through the aligned holes 11 in the permutation plates 32, thence through the aperture I23 of the scanning cylinder 83 onto the cathode 85 of photocell 84, thereby stimulating the emission of electrons therefrom and thus permitting current to flow in the source circuit which is coupled by means of resistance I35 to the control circuit for grid I38.- The grid I38 is influenced thereby so as to cut off the flow of electrons'from cathode I31 to plate I48 and thus reduce the plate circuit of the tube I38 substantially to zero. Cutting off the plate circuit of tube I36, which is the source circuit of the grid control circuit of tube I49, renders the grid I 5| more positive and increases the flow of current in the plate circuit of tube- I49 sufficiently. to actuate relay I51 to hold the armature I58 thereof against contact I59 connected to battery IBI to impress marking current on the line wire I62.

When the transmission of signaling impulses over the line I62 (Fig. 13) is to be initiated, the scanning cylinder 83 is permitted to rotate in response to the depression of a key lever I3 to transmit first a start impulse of spacing nature of duration commensurate with thegwidth of portion IIZ (Fig. 14) on the scanning cylinder shown developed in Fig. 8. It will be observed that, although an alignment of holes 11 indicative of the stop signal always obtains in the permutation plates 32 irrespective of their selective or permutative positions, the beam of light is cut off by the scanning cylinder 83 as it begins the aforesaid rotation. After the portion 2 has been traversed, the code impulses of marking and spacing nature, depending upon the presence /or absence of apertures I02 in the circumferential row corresponding to the selected character, are transmitted. The particular character to be transmitted is governed, of course, by the setting of permutation plates 32 corresponding to the key lever depressed to efi'ect an alignment of holes in said plates in registry with the circumferential row in the scanning cylinder corresponding to said transmitted character. Because the circumferential row I80 on cylinder 83 embraces stop slot I23, and an opening 11 in registry with said row always obtains, the light beam directed upon the photocell 84 during the stop period is cut ofi invariably for a predetermined time interval indicative of the start impulse interval commensurate with the portion IIE on the scanning cylinder 83. In this connection it is noted that the staggering of holes in plate I5 and permutation plates 32 is consistent with the staggering of the. circumferential rows in the scanning cylinder 83. For example, if the cylinder 83 were to be rotated so that the actual beginning of a signal row 18 (Fig. 8) were in registry with its corresponding slot in the lower row of holes 16 and let in plates and 32, respectively, the beginning of a row 19 will be in registry with its corresponding slot in the upper row of holes 16 and mi in said plates I5 and WI, respectively.

The cutting off of the light of photocell 8G influences the grid I558 so as to permit the flow of current in the plate circuit of tube Ito, thereby influencing the grid Isl of tube MI to render grid IE I more negative, thereby cutting off the flow of current in the plate circuit of tube use, and hence actuating relay I51 in such a manner as to permit spring Itl to move armature I53 to the dead contact I63, whereupon a spacing impulse will betransmitted over the line wire I62. The signals thus transmitted over line wire I52 may be utilized to control the operation of a facsimile printer or recorder, for example, of the type disclosed in U. S. Patent No. 2,000,083. The signals transmitted, for example, are directed through a line coil I65 of the facsimile printer thence to ground. The facsimile printer disclosed schematically in Fig. 13 comprises the printing or recording wheel I66 which is concurrent potential of opposite polarity is applied to the points 361 and 369 of resistance 310. When no light is applied to the photoelectric cell 36I there will be on the line 31I312 a direct current from battery 313. When the photoelectric cell is illuminated by chopped light (under the control of the striated portions of the cylinder shown in Fig. 11)' and alternating current is generated, the alternating current will be rectified by rectifier 365, and the output is such as to produce a potential about twice the potential of battery 313 so that there will be supplied on line 31I- 312 polar signals for the operation of a receiver 31%. When a scanning cylinder according to the form shown in Figs. 11 and 12 is used, the width of the slots or apertures in plate 15 (Fig. 2) should be commensurate with the striations I25 in Fig. 11, so as to obtain sharp outlines of the alternations or light changes.

Modifications In Figs. 16 and 17 is shown a tape controlled photoelectric facsimile transmitter. With this embodiment the scanning cylinder arrangement a .with a worm gear I19 fixed to the main operating shaft I15. Fixed to the main shaft I15 is the driving portion I'Iil of a single-tooth grab clutch,

the driven portion ml of which is slidably mounted on shaft I15. The driven portion IBI has engagement in tongue and groove manner with a cam sleeve I82. Secured to shaft I15 for constant rotation therewith is a pinion I83 which trolled through a start-stop clutch. As disclosed in said patent, the printing or platen wheel I66 is provided on its cylindrical surface with symmetrical spiral lmife edges which cooperate with an operating member or platen its, having a knife edge arranged transversely of the tape III. Platen its moves with the line coil member I65 and reciprocates vertically therewith in response to the received signals. In responseto a marking signal, the line coil will be actuated upwardly, bringing the platen Its against the printing wheel; then, upon receipt of a spacing signal the line coil moves downwardly under the action of gravity or by means of a return spring, bringing the platen against a stop.

The circuit shown in Fig. 26 is used with a photoelectric transmitter in which a scanning cylinder or light chopper embodying the characteristics illustrated in Figs. 11' and 12 is employed. llvhen the photocell 3% is illuminated by choppedlight, alternating current is delivered from the secondary of transformer 362 to the grid of an amplifying tube 363, the plate of which meshes with a corresponding pinion or gear Ills fixed to a cross shaft I85. Shaft I85 is comparable to or analogous with shaft 12 of the form of the invention shown in Figs. 1 to 7. Shaft its rotates constantly and carries a scanning cylinder (not shown). The scanning arrangement applicable to the presently described form of the invention is substantially similar to the scanning arrangement previously described, except that the scanning cylinder or light chopper is of the form, for example, as shown in'Figs. 9 and 10, wherein a start signal and a stop signal are embodied in each character signal, and wherein provisions have been made for effecting the transmission of such signals from a continuously rotating scanning cylinder mounted on shaft I85. Clutch portion I8I is provided with a flange ltd, which in turn is provided with a cam portion I81 cooperating with arm I88 of a clutch release lever I39 pivotally carried on pivots |9I and I92. The cam sleeve I82 carries integrally thereon'a tape feed control cam I93, a tape sensing control cam I96, a special shutter cam I95, and a transfer mechanism operating cam I98.

The tape sensing mechanism or record reader comprises a series'of tape feeler levers I91, so

. called because of their function in sensing the attributes of a transverse line of tape perforations. Feeler levers I91 are provided with arms points 366 and 361 on a resistance 368. A direct I98 which carry feeler pins I99. Pins I99 are adapted to be projected upwardly through a slot 20I in a tape guide 202, slot 20I being substan-- tially coextensive with the width of the tape. The tape feeler levers I91 are also provided with projections 203 which are engaged by a bail 204 for periodically withdrawing the levers I91 in accordance with each successive feeding or stepping of the record tape. The bail 204 moves as part of a bell crank structure 205 which is actuated, through its follower roller 206 by the tape sensing or record reading control cam I94. The series of feeler levers I91 are rockable upon a common shaft 200. Each of the feeler levers I91 is provided with a pair of abutments 201 and 208 which cooperate with abutment lugs 209 and 2I I terminating arms 212 and 2I3 of a transfer lever 2I4. The transfer T-levers 2I4 are supported on a common shaft 2I5 which in turn is carried by one arm of a bell crank lever 2 I6 pivoted at 2I1, the end of the other arm of which carries a roller 2I8 spring-urged to follow the peripheral surface of the transfer control cam I96. The cam I96 has an apex substantially as shown in Fig. 17, and when it is rotated together with shaft I15 it imparts a regular and reciproeating motion to the 1ever2IB and its associated T-levers 2I4. The depending arms of T-levers 2| 4 terminate in disc-shaped portions 2I9,

through which said T-levers are articulated to connecting bars 22I individual to each T-lever 2I4. Connecting bars 22I are supported in suit-.

able guideways (not shown) for longitudinal and parallel movement.

In accordance with the timed action of bell crank lever 205 and transfer operating lever 2I6, the set of feeler lever I91 will first be permitted to rotate counterclockwise, during which time those levers I91 whose pins I99 are not blocked by the record tape 222 (Fig. 18), but which are brought into registration with a perforation thereof, will be permitted to rotate until their respective shoulders or abutments 208 register opposite the abutment lugs 2II of the transfer levers 2I4, while the others which are not permitted so to do will remain in the position shown in Fig. 17, with their shoulders 201 in registration with the abutment lugs 209. Immediately following the establishment of this condition, the cam I96 which moves lever 2I6 counterclockwise forces the several transfer T-levers 2I4 into engagement with their respective feeler levers I91 and, depending upon which of the two positions the feeler levers I91 happen to assume, T-levers 2I4 will be correspondingly positioned and will impart a similar positionment to their associated bars 22I. perforations present in each transverse align- In this manner the combination of 7 ment in the tape is translated simultaneously to to register with the central perforations 229 of the control tape 222 in accordance with the Wellknown practice. In this manner the single shaft I15 through its cam sleeve I82 operates all of the mechanical agencies that control th record.

' reader or tape sensing mechanism.

Particular attention is directed to the fact that all of the feeler levers I91 are brought back to a normal or starting position atsome definite point in each cycle of operation, yet the transfer levers 2I4 and articulated slide bars 22I are not restored at this time, but may be set in conformity with a new code combination regardless of their previous position. This practice permits of an overlap in the operation of the two sets of levers,

namely, feeler levers I91 and T-levers 2I4, and allows the permutation plates 232 (comparable to the permutation plates 32 shown in the first-described embodiment of the invention) maximum time of rest during each cycle of operation.

Connecting bars 22I are each provided at their left end (as viewed in Fig. 17) with an upstanding lug terminating in a disc-shapedlportion 233, having pivotal articulation with a corresponding series of slide bars .234, namely, six in the present embodiment, corresponding to the six code signal perforations 235 in the tape 222. Each of the slide bars 234 is provided with a vertically extending lug 238 which carries fixed thereto a stud 231. of each stud 231 is a permutation plate 232. To

permit slidable movement of plates 232 by their I respective studs 237, the plates 232 are slotted in well-known manner. The permutation plates 232 are provided with apertures similar to apertures IOI inplates 32. The apertures, therefore, in plates 232 are arranged in permuted manner so that from each permuted setting of plates 232 an alignment of apertures will occur to permit the light from the exciter lamp to impinge upon the photoelectric cell and to be scanned by the proper circumferential row of apertures in the scanning cylinder.

In addition to the six code shutters or permutation plates 232, there is an additional plate or shutter associated with an extra slidebar 238 (Fig. 16). The function of the shutter associated with the slide 238, when in its extreme right-hand position, is to close all of the light apertures and so prevent the transmission of signals, even though shaft I85 (with the scanning cylinder carried thereon) is rotating. Since the stop signal is a no light condition, the scanning cylinder must be the opposite of that for the keyboard facsimile transmitter described in connection with Figs. 1 to 8. scanning cylinder must be of the type shown in Figs. 9 and 10, wherein translucent portions are provided for the start and other spacing signals. Slide bar 238 is pivotally articulated at its right-' hand end (Fig. 17) with the depending arm of a lever 239 pivoted at 240. Also mounted on pivot 240 is a lever 24I, carrying a follower roller 242 normally held against the periphery of cam I95 through the action of spring 243. Levers 239 and MI are normally biased toward each other by a spring 244. Carried on shaft I is a cam 245 which cooperates with a follower roller 246 carried on a locking bail 241. Each of the slide bars 234 and 238 are provided with a vertical locking lug 248 which cooperates with the locking bail 241, so that as the bars 234 and 238 are operated to their rightward or leftward positions by the connecting bars 22I, the permutative setting is maintained until, at a proper time, a new setting is permitted to be set up in the selector bars. In this connection; it is observed that the articulated lever 239 and 24I, along with the spring 244, serves its purpose by being put undentension when shaft I15 comes to rest. but the :ide bar 238 is held by locking lever 241 Fixed to the opposite ends In other words, the

in its light conducting position, so that the signal being transmitted will be completed; but will close as soon as the stop impulse is reached, whereupon cam 245 acts to release locking lever 2M. Thereafter, the scanning cylinder will rotate without transmitting any signals of any kind until the sleeve I85 is again started.

ing. Cam I96 in its rest position acts to hold the bell crank lever 285 in. its counterclockwise position, thus holding the feeler levers I91 in their clockwise position with the feeler pins I99 withdrawn from the tape 222. Cam I93 in its rest position acts to hold lever 225 in its clockwise position, and cam I96 acts to hold the transfer operating lever 2I6 in its clockwise position.

A paper tension control arm or taut tape lever 225i is pivotally supported at252 on a bracket 253 and. is shown in Fig. 17 in its counterclockwise position. In this position, which is the taut tape position, an interfering member 256, pivotally supported at the left end of taut tape lever I, is held out of cooperative relation with depending arm 255 of a bell crank lever 256. Bell crank 256 is pivotally mounted on pivot 251i and is normally biased by a spring 258 in a clockwise direction to hold a follower roller 259 carried at the end of the horizontal arm of the bell crank lever 256, against the periphery of a cam 26I fixed to the shaft I85. Since the shaft I85 is constantly rotating, the constantly rotating cam 26I will continually rock the bell crank lever 256, thus oscillating the arm 255; but when the tape is taut and the lever 25I is held in its counterclockwise position as shown in Fig. 17, the toe or tip 262 of the lower extremity of member 255, being out of register with the lever 255, will not be actuated thereby, and the lever I68 will.be held in its clockwise position so as to hold the driven portion I8I of the clutch out of engagement with the driving portion I16. However, when the tape becomes slack and the taut tape lever 25I assumes its clockwise position, the member 256 will be raised to bring the toe 262 upwardly into register or cooperative relation with the oscillating arm 255 of bell crank lever 256', so that upon its oscillatory movement lever arm 255 will, through the toe 262, impart corresponding movement to the depending arm 254i. Incidentally, this actuation of lever arm 254i is not imparted to the taut tape lever 25I because of the fact that the depending arm 254i is loosely mounted on lever 25L Arm 256i is arranged to be slidable between a pair of lugs 268 integral with the clutch lever I69, and is thus articulated to lever I89. Accordingly, upon each oscillation of arm 255, the clutch release lever I89 will likewise be oscillated, due to the cooperaitve relationship between arm 255 and lever 256 through the agency of the toe 262. Thus, since shafts I65 and I75 are rotating at the same rate of speed, the rotation of shaft I15, and hence cam sleeve I82, will be substantially continuous during $18- nal transmission. It is therefore seen that .the

base portion 265 area plurality of key levers 214 operating cams I99, I94, I95, and I96 will not be released for operation if the tape is taut, since,

then the interfering member 254 will be in a position whereby its projection or toe 264 is out of register with lever arm 255. Owing to their particular construction, levers 256 and 254 perform the function of preventing any split signals, by insuring a single rotation of clutch I8I per signal. It is observed that by providing a singletooth grab clutch, sleeve I82, during signal transmission, will rotate in proper phase relation with shaft I85.

, Assuming that signals are being sent by the record reader, the cam sleeve I82 makes one revolution for each code signal. Upon the initiation of rotation of sleeve I82, the cam I95 thereon begins to rotate to bring its apex out of register with the follower roller 242 whereupon spring 293 rotates the compound levers 2M and 239 clockwise to bring the slide 238 to its leftward position, in which position the shutter slide 232 associated therewith is also actuated to its leftward or light conducting position, whereat its apertures permit light to be transmitted, through any of the aligned apertures in the remaining permutation plates 232, from the light source onto the phototelectric cell. At the end of each revolution of the cam I95, the slide 238, when permitted by the lever 291 as previously described, is returned to its rightward position to bring the shutter slide 232 associated therewith to its rightward position to shut off all the light apertures. Again, when the tape is taut and the member 256 is held in its lowermost position whereby shaft I85 rotates continuously and the cam sleeve I82 is arrested in its rotation, the slide 238 is held in its rightward position and the permutation plate 232 associated therewith acts to shut 011 all the apertures in the remaining plates regardless of the permutative setting imparted thereto by the connecting bars 22!.

As previously indicated, the stop condition is a no light condition and the signal controlling characteristics of the scanning drum are reverse to those for the transmitter shown in Figs. 1 to 8; that is, according to the modified form, spacing signals are represented by the apertures instead of the solid portions in the scanning cylinder. Accordingly, the marking and spacing conditions are reversed on the photocell, and the circuit therefor is similar to the circuit illustrated in Fig. 13, except that, as previously alluded to, the normal grid bias of the electronic tube in the first stage of amplification is changed from a slightly negative condition to a more negative condition and the photoelectric cell is connected in such a manner as to bias the grid positively when light falls upon the photocell.

In Figs. 19 to 21 is shown another modification of the present invention. In this form of the photoelectric cell. A motor 266 is mounted on the base portion 265 and has a shaft 261 carrying a pinion 268 having meshing engagement with a worm gear 269 loosely mounted on a cross shaft 2'. Integral with gear 269 is the driving ortion 2712 of a grab clutch 213. Carried in the pivotally mounted on a common shaft 215 supported in the rear portion of the base 265. A universal bail member 216 pivoted at 211 is located beneath the key lever 214 and is adapted to span said key levers for cooperation therewith. Fixed to the universal bail 216 is a bracket 280, to the extremity of which is pivoted a clutch release am 281, comparable to clutch release arm 46 shown in Fig. 4. Similarly, clutch release arm 281 is provided at its end with a shoulder 282 cooperating with the pointed end of a depending arm 283 of an intermediate lever 284 pivotally supported at 285 to a bracket 286 mounted on base portion 265 (Fig. 20). Lever 284 is also provided with an arm 281 carrying on its end a follower roller 288 which cooperates with arm 289 of a clutch release lever 291 pivoted at 292 to a bracket 293 mounted on the base 265. Clutch release lever 291 is provided with a fol lower arm portion 294 which cooperates with a cam 295 conformed on a flange 296 of the driven portion 291 of grab clutch 213. A spring-298 compressed between the flange 296 and a collar 299 tends to force the driven portion 291 of clutch 213 rightwardly (as viewed in Fig. 20) into meshing engagement with the driving portion 212 whenever the clutch release lever 294 is disengaged from the cam portion 295. Thus it is seen that when a key lever 214 is depressed, the bail 216 is rotated counterclockwise to impart leftward movement to the arm 281 which 2 causes the shoulder 282 to actuate, through its cooperation with arm 283, the lever 284 clockwise which in turn imparts counterclockwise rotation to the lever 289 to effect the release of the driven portion 291 of clutch 213 so that the spring 298 will carry the portion 291 intoengagement with the driving portion 212, thereby imparting rotation to shaft 215.

To the left end of shaft 211 as viewed in Fig. 19 is fixed the scanning cylinder 300. Scanning cylinde: 301 is arranged to rotate within a housing 302 which is provided with a long slot or opening 303. Positioned within the scanning cylinder 301 is a photoelectric cell 309 comparable to photoelectric cell 84 shown in Figs. 5 and 7. As previously mentioned, there is associated with each key lever 216, a shutter 305. The shutters 305 are arranged in juxtaposition in front of the opening 303 so that when all of the shutters 305 are in their upper position all of the light will be shut out from the photoelectric cell 304. As shown in Fig. 21 each of the shutters 305 is integral with a slide portion 306 which is guided in a comb or guide portion 30?. The lower portion of slide 306 is articulated to its associated key lever 214 through a pin and slot connection. A spring 308 is distended between each slide member 306 and a spring bar secured to the comb or guide member 301. In this manner, the key levers are held or maintained in their horizontal position. Each of the slides 306 is provided with a lug 309 which cooperates with a locking bail 311. Upon the depression of a key lever 214 and the release of the clutch 213 for rotation, the bail 311 is rotated counterclockwise to hold the operated slides 306 in their operated position under the control of a cam 312. The timing of cam 312 is such as to lock the depressed key lever-in its operated position and to lock the unoperated key levers in their unoperated position during the period of transmission of the facsimile signal. Suitably mounted on the base portion 265*is the electric'lamp 313. The axes of course, coincident with the opening 303 in the housing 302. Each of the shutters 305 is provided with a slit or narrow aperture 314, which is normally disposed, when the key levers 214 are in their horizontal or unoperated position,

above the opening 303, so that upon the depression of a key lever 214 the opening 314 of its associated slide 305 is brought downwardly into register with the opening 303 into the path of the light beam from lamp 313.

Another form of the invention is shown in Figs. 22 to 25, and is a. variant of the form shown in Figs. 19 to 21. Accordingly, those parts which are common to both forms are not shown nor described and reference should be had to the form shown in Figs. 19 to 21 for a complete understanding of the form shown in Figs. 22 to 25. On the shaft 321 (which is comparable to shaft 211 inFig. 20) is fixed the scanning cylinder 322. Scanning cylinder 322 rotates within a housing 323 which is suitably mounted on the base portion 324. Fitted into the open end of housing 323 is a flanged disc,325, whichcarries rigidly therein the ends of a plurality of transparent light carrying rods 326, such as quartz or other material oflike optical properties. The housing 323 is provided with a series of openings 321 ar-' hold the key levers 329 in their horizontal or unof the photoelectric cell and the lamp 313 are, 7

operated position. The slides 331 are slidably supported in a guide member or comb 335 mounted on the base portion 324. Slides 331 are each provided with a shutter portion 336 contiguous with the housing 323 and guided by a plate 331. The shutters 336 act to cut off the beam of light to the photoelectric cell when the key levers 329 are in their unoperated position. Also, slides 331 ar each provided with an arm 338 terminating in a reflecting surface 333. As indicated in Fig. 23, the reflecting surface 339 is disposed at substantially an angle of 45 degrees with the plane of the-slide 331, as well as with the beam of light produced by the optical system 351.

The optical system 341 comprises a housing 342 in which is supported an electric lamp 343 and a condensing lens 344, as well as a lens 345, for producing a concentrated beam of light with as nearly parallel rays as practical. The reflecting surface 339 is normally maintained above the beam of light, indicated at 346 in Fig. 22, when the key levers are in their horizontal -or unoperated position.

rod 326 and thence onto the cathode of the photo-- electric cell 328; and as the scanning cylinder 322 rotates a single revolution, the light beam is cut non-operated positions simultaneously so as to hold a single key and slide operated during the transmission of a character signal.

In Fig. 25 is shown an alternate form of refiecting surface comprising a. reflector 355 mounted on an arm 356 comparable to arm 338 of slide 33!. With this construction the reflector 355 may be made of highly reflective material; that is,-the beveled surface 351, which was comparable to surface 339, may be made from a material different from the material composing the supporting structure, and such as will take a high polish.

What is claimed is:

1. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas, each area corresponding to a character and having portions with different light controlling abilities arranged according to the character represented, means to select an area according to the character to be transmitted, means to activate the photoelectric cell according to the light controlling abilities of the different areas, and means to generate signals according to the activation of the photoelectric cell.

. 2. In a keyboard facsimile transmitter, a series of keys, a, photoelectric cell, means to activate said photoelectric cell, a screen containing a representation of the signal impulses to be transmitted formed as a series of groups of transparent or opaque portions, each group specific to a character, means controlled by said keys whereby said screen is passed between said activating means and said photoelectric cell so as to cause said representation of the impulses to affect said photoelectric cell.

3. In a keyboard facsimile transmitter, a series of keys, a photoelectric cell, means to activate said photoelectric cell, a screen containing a representation of the signal impulses to be trans-.

mitted formed as a series of groups of transparent or opaque portions, each group specificto a character, means controlled by said keys whereby said screen is passed between said activating means and said photoelectric cell so as to cause said representation of the impulses to control the generation of signals according to the activation of the photoelectric cell.

4. In a keyboard facsimile transmitter, a series of keys, 2. photoelectric cell, means to activate said photoelectric cell, a scanning cylinder containing a representation of the signal impulses to be transmitted formed as a series of groups of transparent or opaque portions, means controlled by said keysfor releasing said scanning cylinder for one revolution only. and a shutter means controlled by said keys efiective when operated to cause said activating means to influence said photoelectric cell in accordance with one of said groups of transparent'and opaque portions.

5. In a photoelectric transmitter, a character member having opaque and transparent portions arranged in lines, a single line for each charaaeaeea the lines on the character member, and means to activate the photoelectric cell for the duration of a signal interval according to the character line selected.

I 6. In a facsimile transmitter, a photoelectric cell, a scanning device having opaque and transparent portions arranged in a series of lines, one for each character to be transmitted, an exciter lamp adapted to activate the photoelectric cell, means to select a character line, means including the'scanning device to successively modulate the effect of the exciter lamp on the photoelectric cell according to the character of the line selected.

7. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas, each area corresponding to a character and having portions with different light controlling abilities arranged according to the character represented, shutter means to select an area according to the character to be transmitted, means to activate the photoelectric cell according to the light controlling abilities of the different areas, and means to generate signals according to the activation of the photoelectric cell.

8. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas, each area corresponding to a character and having portions with different light controlling abilities arranged according to the character represented, permutation means to select an area according to the character to be transmitted, means to activate the photoelectric cell according to the light controlling abilities of the'difierent areas, and means to generate signals according to the activation of the photoelectric cell.

9. In a facsimile printing telegraph transmitter, a photoelectric cell, a scanning device having a plurality of peripheral areas, one for each symbol, each having elemental control areas corresponding to the light and dark areas of a so symbol, a light port for each peripheral area, a plurality of permutation members selectively positionable in code combinations to select one of said ports to admit light onto said photoelectric cell, and means to generate signals according to the activation of the photoelectric cell.

II). In a photoelectric transmitter adapted to transmit facsimile signals comprising a scanning device having a plurality of areas, each area ter comprising a plurality ofapertured plateshaving for each permuted setting an opening corresponding to each area; and means to generate signals according to the activation of the photoelectric cell. 11. In a photoelectric transmitter adapted to transmit facsimile signals comprising a scanning device having a plurality of peripheral areas, one for eaclil symbol, each having elemental control areas corresponding to the light and dark areas of a scanned symbol, a sourceof light, a photoelectric cell, a light shutter comprising a plurality of apertured plates having for each permuted setting thereof an opening corresponding to each peripheral area whereby light is admitted from said source onto said photoelectric cell, and means to generate facsimile signals according to the activation of said photoelectric cell. 12. In combination, a telegraph transmitter,

means for radiating light, light sensitive means in the path of said light, a scanning device located between said light radiating means and said light sensitive means for interrupting said light, said device having a plurality of peripheral areas, one for each symbol, each having elemental control areas corresponding to the light and dark areas of a scanned symbol, a light shutter comprising a plurality of apertured plates having for each permuted setting thereof an opening corresponding to each peripheral area whereby light is admitted from said first recited means onto said light sensitive means, and means to generate signals according to the activation of said light sensitive means.

13. In a facsimile printing telegraph transmitter, a photoelectric cell, a scanning device having a plurality of peripheral areas, one for each symbol, each having elemental control areas corresponding to the light and dark areas of a scanned symbol, a light port for each peripheral area, a plurality of transparent light-carrying rods, one extending from each port to said photoelectric cell, a plurality of permutation members selectively positionable in code combinations to select one of said ports to admit, through the associated rod, light onto said photoelectric cell, i

arranged according to the character represented,

means for producing a concentrated beam of light, means for reflecting said beam of light,

' a photoelectric cell, a light shutter comprising a plurality of apertured plates having for each permuted setting an opening corresponding to each area, a plurality, of light-carrying rods, one extending from each opening to said photoelectric cell, for carrying said light from said reflecting means to said photoelectric cell, and means to generate signals according to the activation of the photoelectric cell.

15. In a photoelectric transmitter, a constantly moving scanning device, an intermittently operating sensing device, and means to synchronize the intermittent operations of the sensing device with the motion of the scanning device.

16. In a photoelectric transmitter, means to produce a beam of radiant energy, a plurality of scanning elements, a photoelectric cell, radiation deflecting means individual to each scanning element, means to move any deflecting means into the path of the beam to deflect radiant energy onto its corresponding scanning element to determine the information to be transmitted, means to project the radiant energy passing the scanning means onto the sensitive element of the photoelectric cell, and means to generate information-carrying signals according to the activation of the photoelectric cell.

17. In a photoelectric transmitter, a source of illumination, a photoelectric cell, a screen containing striations corresponding to a specific character and, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, and means to pass said screen between said source and said cell so as to cause said signal representations to activate said cell.

18. In a photoelectric transmitter, a source of light, a photoelectric cell, a screen containing striations, each striation corresponding to a specific character and comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen between said source and said cell, and means to select a striation to cause the signal representation thereon to activate said cell.

19. In a photoelectric transmitter, a source of light, a photoelectric cell, a screen containing striations, each striation corresponding to a specific character and comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen between said source and said cell, and a permutation code mechanism operable to select a striation to cause the signal representation thereon to activate said cell.

20. In a photoelectric transmitter, a source of light, a photoelectric cell, a screen containing striations, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen between said source and said cell, and a plurality' of apertured plates operable permutably to effect an alignment of apertures opposite any one of said striations to cause the signal representation on said striation to activate said cell.

21. In a photoelectric transmitter, a source of light, a photoelectric cell, a screen containing striations, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means for constantly rotating said screen to pass its periphery between said source and said cell, a signal controlling medium, intermittently operated means for controlling, through said medium, the signal to be transmitted, and means associated with said first-mentioned means effective under the control of said medium to govern the operativeness of said intermittently operated means.

22. In a photoelectric transmitter, a source of light, a photoelectric cell, a screen containing striations, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen between said source and said cell, a plurality of light-carrying rods, one extending from each striation to said cell, and 'means to select a striation to enable the passage of said light through the associated rod onto said cell to cause the signal representation on said striation to activate said cell.

23. In a keyboard photoelectric transmitter, a series of keys, a source of light, a photoelectric cell, a screen containing striations corresponding to a specific character and, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen between said source of light'and said cell, and a shutter means associated with said keys normally effective to prevent the impingement of said light upon said cell, and effective upon operation of said keys to admit said light to cause the signal representation on a striation to activate said blocks of signals, and applying to the line in series with the direct current an opposite potential of higher value produced by the rectified impulses to form impulses of polar nature corresponding to said signals.

25. In a photoelectric transmitter, an area assigned to each of. a plurality of signals to be transmitted, means to illuminate each area when a corresponding signal is to be transmitted, a single photo-sensitive device, a light conducting rod leading from each area to the photo-sensitive device, and means controlled by the photo-sensitive device to generate signals according to the light transmitted through the rods.

26. In a photoelectric transmitter, a constantly rotating scanning cylinder, a plurality of arrangements of opaque and transparent light admitting areas in said cylinder, a source of light, a photo-sensitive device, means to select one of the plurality of arrangements at a time to control the impingement of the light from the source on the photo-sensitive device, and means associated with said selecting means and eifective automatically between signalling intervals to cut ofi the light from all areas.

27. The method of generating polar signals for telegraphic transmission, which comprises the steps of supplying one polarity of potential continuously from a direct current source to the circuit, generating blocks of impulses according to signals to be transmitted, transforming said blocks of impulses into alternating current, rectifying said transformed blocks of signals, and applying to the same circuit in series with the direct current an opposite potential of higher value produced by the rectified impulses to form impulses of polar nature corresponding to said signals.

28. In a keyboard facsimile transmitter, a series of keys, a photoelectric cell, means to activate said photoelectric cell, a screen containing a plurality of groups of representations of signal aacasea vate said photoelectric cell, a scanning cylinder containing a representation of thesignal impulses to be transmitted formed as a series of areas having difierent light controlling abilities, means controlled by said keys for releasing said scanning cylinder for one revolution only, and-a plurality of laminated shutter plates controlled by said keys effective when operated to cause said activating means to influence said photoelectric cell in accordance with one of said series of areas.

32. In a keyboard facsimile transmitter,a series of keys, a photoelectric cell, means to activate said impulses to be transmitted, each group specific to a character and formed as a series of apertured and unapertu'red portions, and means controlled by said keys whereby said screen is passed between said activating means and said photoelectric cell so as to cause said representation of the impulses to affect said photoelectric cell.

29. In a keyboard facsimile transmitter, 21.

series of keys, a photoelectric cell, means to activate said photoelectric cell, a screen containing a plurality of groups of representations of signal impulses to be transmitted, each group arranged according to a specific character and formed with portions having different light controlling. abilities, and means controlled by said keys whereby said screen is passed between said activating means and said photoelectric cell so as to cause said representation of the impulses to affect said photoelectric cell.

30. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas,

each area corresponding to a character and having portions with difl'erent light controlling abilities arranged according to the character represented, shutter mechanism, means to actuate said mechanism to select an area according to the character to be transmitted, means to activate the photoelectric cell according to the light controlling abilities of the different areas, and means to generate signals according to the activation of the photelectric cell.

' 31'. In a keyboard facsimile transmitter, a sephotoelectric cell,a scanning cylinder containing a representation of the signal impulses to be transmitted formed as a series of areas having diflerent light controlling abilities, a plurality of laminated plates apertured in accordance with a permutation code, and means controlled by said keys for operating said plates permutably to cause said activating means to influence said photoelectric cell in accordance with the key operated.

33. In a photoelectric transmitter, a character member having areas of different light controlling abilities arranged in lines, a single line for each character, a photoelectric cell, means to select one of the lines on the character member, and means to activate the photoelectric cell for the duration of a signal interval according to the operation of said selecting means. 7

34. In a photoelectric transmitter, a character member havingareas of different light controlling abilities arranged in lines, asingle line for each character, a photoelectric cell, shutter mechanism to select one of the lines on the character member, and means to activate the photoelectric cell for the duration of a signal interval according to the operation of said shutter mechanism.

35. In a photoelectric transmitter, a character member having areas of different light controlling abilities arranged in lines, a single line for each character, a photoelectric cell, activating means therefor, a plurality of laminated plates pulses to be transmitted formed as a series of groups of transparentor opaque portions, means controlled by said keys for releasing said scanning cylinder for one revolution only, and shutter mechanism associated with said keys effective upon operation of said keys to cause said activating means to influence said photoelectric cell in accordance with one of said groups of transparent and opaque portions.

37. In a keyboard facsimile transmitter, a plurality of key levers, selector bars arranged transversely of said key levers 'and controlled thereby, a scanning'cylinder disposed above and parallel to said selector mechanism, said cylinder containing a representation of the signal impulses to be transmitted formed as a series of groups of transparent and opaque portions, a single photoelectric cell coextensive with the series of representations on said cylinder, a single 7 means to activate said photoelectric cell, means ries of keys, a photoelectric cell, means to acticontrolled by said keys for releasing said scanning cylinder for one revolution only, and a shutrow, a shutter mechanism to control said portsto admit light onto said photoelectric cell, and means to generate signals according to the activation of the photoelectric cell.

39. In a facsimile printing telegraph transmitter, a photoelectric cell, a scanning device having a plurality of peripheral areas, one for each symbol, each peripheral area having elemental control areas corresponding to the light and dark areas of a scanned symbol, a light port for each peripheral area, a shutter mechanism comprising a plurality of laminated plates apertured according to a permutation code and having for each permuted setting an alignment of apertures corresponding to each peripheral area, and means to generate signals according to the activation of the photoelectric cell.

40. In combination, a telegraph transmitter, means for radiating light, light sensitive means in the path of said light, a scanning cylinder 10- cai'ed between said light radiating means and said light sensitive means for interrupting said light, said cylinder having a plurality of peripheral rows, one for each symbol, each row having elemental control areas corresponding to the light and dark areas of a scanned symbol, shutter mechanism corresponding to said peripheral rows whereby light is admitted from saidfirst recited means onto said light sensitive means, and means to generate signals according to the activation of said light sensitive means.

41. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas, each area corresponding to a characterand having portions with diflerent light controlling abilities arranged according to the character represented, means to select an area according to the character to be transmitted, a plurality of lightcarrying rods, one extending from each area to said photoelectric cell, means eifective through said light-carrying rods to activate the photoelectric cell according to the light controlling abilities of the diflerent areas, and means to generate signals according to the activation of the photoelectric cell.

42. In a facsimile printing telegraph transmitter, a photoelectric cell, a scanning cylinder having a plurality of peripheral rows, one for each symbol, each row having elemental control areas corresponding to the light and dark areas of a scanned symbol, a light port for each peripheral row, a plurality of light-carrying rods contained within the scanning cylinder and each conformed so as to present one end thereof toward a light port and the opposite end thereof toward the photoelectric cell, means effective through said light-carrying rods to activate the photoelectric cell according to the light control-' ling abilities of the different areas, and means to generate signals according to the activation of the photoelectric cell;

43. In a photoelectric transmitter, a constantly rotating scanning cylinder, a step-by-step tape sensing device, and means to synchronize the 7 stepping of the sensing device with the motion of the scanning cylinder.

44. In a photoelectric transmitter, a constantly rotating scanning cylinder, a step-by-step tape sensing device, and cam means to synchronize the stepping of the sensing device with the motion of the scanning cylinder. 7

45. In a photoelectric transmitter, a constantly moving scanning device, a cam means associated with said scanning device, an intermittently op,

erating sensing device, and means associated with said sensing device and cooperable with said cam means to synchronize the intermittent operations of the sensing device with the motion of the scanning device.

46. In a photoelectric transmitter, a constantly moving scanning device having a plurality of areas, means to select an area according to the character to be transmitter, an intermittently operated sensing device for controlling the operation of said means, and means to synchronize the intermittent operations of the sensing'device with the motion of the scanning device.

47. In a photoelectric transmitter, a photoelectric cell, a constantly moving scanning device having a plurality of areas, each area corresponding to a character and having portions with diiferent light controlling abilities arranged according to the character represented, means to select an area according to the character to be transmitted, an intermittently operated sensing device for controlling the operation of said selecting means, means to synchronize the intermittent operations of the sensing device with the motion of the scanning device, means to activate the photoelectric cell according to the light controlling abilities of the different areas, and means to generate signals according to the activation of the photoelectric cell.

48. In a keyboard photoelectric transmitter, a series oi keys, a source of light, a photoelectric cell, a screen containing striations, each striation comprising a series of transparent and opaque portions representing signal impulses to be transmitted, means to pass said screen in a continuous movement between said source of light and said cell, and shutter mechanism eifective upon operation (if said keys to admit said light to cause the signal representation on a striation to activate said cell.

49. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of rows of signal controlling areas, each row specific to a character and having areas with difierent light controlling abilities arranged according to the character represented, means to select a row according to the character to be transmitted, means to activate the photoelectric cell according to the light controlling abilities of the diflerent areas, and means to generate signals according to the activation of the photoelectric cell.

50. In a photoelectric transmitter, a constantly moving scanning device, an intermittently operating sensing device for controlling the eflectiveness of said scanning device, and means to symchronize the intermittent operations of the sensing device with the motion of the scanning device.

51. In a photoelectric transmitter, a constantly rotating scanning cylinder, a plurality of arrangements of gpaque and transparent light controlling areas in said cylinder, a source of light, a photo-sensitive device, a plurality of apertured bars operable permutably to select one of the plurality of arrangements to control the impinge- 52. The method of generating polar signals for' the graphic transmission, which comprises the steps of supplying one polarity of potential continuously from a direct current source to the circuit, generating intervals of current-no-current signals, transforming said signals into alternating current intervals, rectifying said alternating current, and applying to the same circuit in series with the direct current an opposite potential of higher value produced by the rectified current to form impulses of polar nature corresponding to said signals.

53. In a facsimile transmitter, a photoelectric cell, a scanning device having a plurality of areas, each area corresponding to a character and having portions with variant light controlling abilities arranged according to the character represented, means to select an .area according to the character to be transmitted, means to activate the photoelectric'cell according to the light controlling abilities of the different areas, and

means to generate signals according to the activation of the photoelectric cell.

54. In a signal transmitting system, a photoelectric cell, means to illuminate the photoelectric cell for varying intervals according to the signals to be transmitted, means to interrupt the illumination a plurality of times during each interval, means to generate blocks of alternating current impulses corresponding to the-illumination of the cell, a signaling circuit, means to apply direct current potential of one polarity to the line, means to rectify the blocks of alternating current, and means to apply the potential of higher value resulting from the rectified current to the signaling circuit to oppose the direct current potential to produce polar signals corresponding to the illumination of the photoelectric cell.

LOUIS M. POTTS.

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