US2949599A - Electrical signalling receiver for displaying lines of characters - Google Patents

Description

Aug. 16, 1960 J. H. JONES 2,949,599

ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS 8 Sheets-Sheet 1 Filed Dec. 2, 1957 INVENTOR. Jay/v /7. Jam 5 Aug. 16, 1960 J- HiJONES 2,949,599

ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS 8 Sheets-Sheet 2 Filed Dec. 2, 1957 INVENTOR. Jamv h. Jaw-s Aug. 16, 1960 J. H. JONES ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS 8 Sheets-Sheet 5 Filed Dec. 2, 1957 INVENTOR. Ja /v bf Jam-'5 Arr-00v! Aug. 16, 1960 J. H. JONES 2,949,599

ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS 8 Sheets-Sheet 4 Filed Dec. 2, 1957 INVENTOR. JaMV/V. Jam/5 Aug. 16, 1960 .1. H. JONES 4 ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS 8 Sheets-Sheet 5 Filed Dec. 2, 1957 INVENTOR. Ja/w Jaw-5 Arrow M Aug. 16, 1960 Filed Dec. 2, 1957 J. H. JONES ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES 0F CHARACTERS 8 Sheets-Sheet 6 INVENTOR. JOHN hi Jawif OW .MWZ

Aug. 16, 1960 J. H. JONES 2,949,599

ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS Filed Dec. 2, 1957 8 Sheets-Sheet 7 /d9 w I I "9) A|k WT I L 1/ W A 9/ FIG-l0 Jaw/v hf Jam's Aug. 16, 1960 J. H. JONES 2,949,599

ELECTRICAL SIGNALLING RECEIVER FOP.

DISPLAYING LINES OF CHARACTERS Filed Dec. 2, 1957 8 Sheets-Sheet 8 /42 //4 Ill 7 i9 INVENTOR.

FIG '/2 Joy/v /7f Ja/vii ELECTRICAL SIGNALLING RECEIVER FOR DISPLAYING LINES OF CHARACTERS John H. Jones, 384 Diablo Court, Palo Alto, Calif. Filed Dec. 2, 1957, Ser. No. 700,160 17 Claims. (Cl. 340-154) This invention relates to apparatus for receiving information in the form of electric or other signals, for accumulating and storing a quantity of such information, and for displaying linm of visible characters representative of such information.

Electric and other signals are used to transmit information over great or small distances: for example, across oceans and continents via radio and cable, or between adjacent parts within a single computing machine. Such signals cannot usually be directly sensed and interpreted by a human observer but must first be converted by a suitable receiver into a form readily perceived by the human senses and readily assimilated by the human brain. A general object of this invention is to provide an improved receiver for such purposes.

Information can be fed into a human being most rapidly and efliciently through the eyes, and in particular by visibly displaying whole lines of characters, preferably one line at a time. Reading speeds exceeding 400 to 600 words per minute can be developed. Heretofore, the display of lines of characters responsive to received signals has usually been accomplished by typing or printing the characters on paper or the like, and the printing process has limited the reception and display rate to speeds much slower than attainable reading speeds, in addition to creating other significant difi'iculties and disadvantages. More recently, electronic and photographic techniques and the like, have been developed and combined to produce faster read-out rates but at the expense of considerable increases in cost, complexity, maintenance requirements and operational difliculties. A more specific object of this invention is to provide compact, reliable and relatively inexpensive, highspeed, signal-responsive apparatus for displaying lines of characproved apparatus for accumulating and storing information which may be displayed or utilized in any other manner. Still another object is to provide improved means for comparing and establishing identity between two entities. Still other objects and advantages will appear as the description proceeds.

According to one aspect of the invention, diiferent characters are displayed selectively by imparting synchronized periodic motions (preferably rotation) to a scanning device and to a member having a plurality of different characters marked thereon, such that the scanning device makes a selected one of said characters visible in a particular display position. Signal-responsive means are provided for adjusting the phase relation between such periodic motions, whereby a received signal controls the selection of a particular character to be displayed. In particular, this is preferably accomplished by stopping and starting one of the periodic motions at selected epochs during a cycle of the other.

Lines of character may be formed responsive .to a succession of received signals by providing a plurality of such mechanisms disposed side-by-side, in combinaaired sa e Patent tion with successively operable trigger devices whereby each of a succession of received signals adjusts the phase relation of a successive one of many independently movable components. The movable components with their associated phase-adjusting mechanisms constitute an information-storage or memory device, whereby many units of information, received successively, can be accumulated and stored for substantially simultaneous display, or for other purposes.

To correlate received information with particular epochs in a reference periodic motion, a novel comparator is provided utilizing an optical commuter in combination with electromagnetically positioned masks and a light-senstive transducer, so disposed and arranged that the transducer provides an electric signal at a selected position of the commuter, selected and controlled by the electromagnetically positioned masks. Thus, by positioning the commuter in accordance with one of two values that are to be compared (e.g., the instantaneous phase angle of the reference periodic motion), and posi tioning the masks in accordance with the other value (e.g., information represented by a received signal), the two values can be compared, and a signal can be provided at the transducer for initiating any desired action upon the establishment of identity, or any other desired relation, between the two values.

In the specific signal-responsive apparatus herein described for displaying lines of characters, the masks are positioned by received signals, the commuter experiences a continuous, reference periodic motion (preferably rotation), and the transducer supplies signals at selected epochs of the reference motion, under control of the received signals, for timing the start of other periodic motions (preferably rotation) in adjustable phase relation to the reference motion. Such phase relations then determining the selection of a line of characters to be displayed.

The invention may be better understood from the following illustrative description and the accompanying drawings. I-ts scope is pointed out in the appended claims.

In the drawings:

Fig. 1 is an orthographic projection showing an embodiment of this invention for displaying lines of characters;

Fig. 2 is a partly schematic vertical section taken generally along the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary vertical section along the line 3-3 of Fig. 1;

Fig. 4 is a detail, taken generally along the line 44 of Fig. 3, showing a rotative drum and other parts within the apparatus for displaying lines of characters;

Fig. 5 is an exploded-detail showing certain parts of the scanning mechanism of the same apparatus;

Fig. 6 is an enlarged fragmentary detail which shows more clearly certain of the parts illustrated in Fig. 2;

Fig. 7 is a sectional detail taken generally along the line 7 7 of Fig. 6;

Fig. 8 is a largely schematic representation of an electro-optical comparator which constitutes a portion of the same apparatus;

Fig. 9 is a schematic, fragmentary section showing a portion of the aforesaid electro-optical comparator, which includes a novel-electro-optical switching device;

Fig. 10 is an enlarged fragmentary detail of a portion of Fig. 9;

Fig. 11 is an orthographic projection of the electrooptical switching device forming a portion of the comparator illustrated in Fig. 9; and

Fig. 12 is a simplified, schematic circuit diagram of certain electrical circuits of the same apparatus.

Before proceeding with a detailed description of the iltaken generally lustrative embodiments it will be helpful to consider certain terminology used in this specification.

The Word receiver is herein used in a broad sense meaning an apparatus or device responsive to signals representative of information, for providing other indicia representative of the same information and usually of a form more readily perceived and assimilated by human beings, but some times of a form useful for further machine operations. In general, the source and form of the received signals are no concern of the present invention. For example, the source may be a distant telegraphic transmitter or the like, or a nearby tape-recording playback device. The information may, for example, be represented by amplitude, frequency, or phase changes in an electric or other signal, or by various combinations of pulses.

For illustrative purposes it will hereinafter be assumed that the received signals consist of successive groups of electric pulses, wherein each pulse may be of either positive or negative polarity, selectively. More specifically, each group may consist of six pulses received simultaneously through six parallel wires and may represent any one, selectively, of sixty-four different characters. An additional timing or control pulse, transmitted through a seventh wire, may be included in each group. It will be understood that signals of many different forms and types may be converted into the particular form here specified through means and techniques within the skill of the art, or that the receiver hereinafter described may be modified to be directly responsive to signals different from the particular form herein specified. Since the possibilities for such conversions and modifications are practically numberless, as will readily be appreciated by those skilled in the art, it will be understood that the specific apparatus herein described is merely illustrative of the invention.

The word character as herein used means any mark, symbol, device, or thing representative of a unit of information, which can be combined with other characters to form larger bodies of information. For example, the characters employed may include, but are not limited to, letters of the alphabet, numerals (in any number system: decimal, binary, or other), spaces, punctuation marks, and arbitrary symbols.

The word synchronized is herein used in a broad sense denoting the time-relation of periodic events occurring at repeating, fixed times relative to one another, not necessarily with equal periods. Thus, harmonically related periodic motions may be said to be synchronized. Similarly, any two periodic values may be said to be synchronized and to have a fixed phase relation if a certain epoch of one value repeatedly occurs simultaneously with a certain epoch of the other, whether or not the periods of the two values are identical. Also, whenever each of two values is synchronized with a third value, the two values are synchronized with each other.

The phrase light transmission (and related phrases) as herein used includes transmission by reflection as well as transmission through transparent and translucent bodies and openings.

Referring now to the drawings, and in particular to Fig. 1, an electrical signalling receiver embodying principles of this invention is contained in a case 1, which may be approximately the size of an ordinary typewriter. Thus, a highly portable, compact apparatus is provided. The front of the case is provided with a recess 2 at the bottom of which there is a viewing aperture 3 of appropriate size and shape for displaying one line of characters, having approximately the size of pica type. The line so displayed may be of any desired length; for example, space may be provided for a line of about 70 characters or columns. A selected character, selected under the control of a received signal (illustratively, a group of electric pulses) is optically projected into each column of the viewing aperture by mechanism hereinafter described. The selection of each character is controlled, as is hereinafter more fully ex- 4 7 plained, by a successive one of a sequence of successively received signals, so that a succession of received signals controls the selection of a plurality of characters which are displayed substantially simultaneously and side-by-side within viewing aperture 3 to spell out a whole line of received information.

Within recess 2 and just above viewing aperture 3 there is a comb-like structure containing a plurality of vertical slots 4, through which light is directed from within the case to illuminate the inter-character spaces of the viewing aperture for preventing the appearance of dark vertical bands or lines between characters of the display.

Fig. 2 is a partly schematic, vertical section of the same apparatus which illustrates the mechanism for projecting a selected character into one column of the viewing aperture. As Fig. 2 indicates, the viewing aperture is preferably covered by a translucent screen 3, which may be a plate of frosted glass, for example. Immediately behind the viewing aperture there is a transparent rotative drum 5. Drum S is supported by any suitable bearings 6, and is rotated counter-clockwise. (as viewed in Fig. 2) at a constant angular velocity 2,, by means hereinafter described. A plurality of different characters are visibly marked, upside-down, on drum 5, as is indicated schematically in Fig. 4 of the drawings. These characters are arranged in a plurality of rows extending lengthwise of drum 5, and in a plurality of columns extending circumferentially about drum 5. Thus, as drum 5 rotates, a plurality of difierent characters in succession pass periodically across each column-position alined with the viewing aperture. A selected character in each column is optically and visibly projected into the viewing aperture by scanning means hereinafter described.

Within drum 5, there are a plurality of axially alined, scanning drums 7, one for each column of the display. Drums 7 are individually rotative upon a shaft 8, which is parallel and off-center with respect to the axis of drum 5 so that each of the drums 7 has a circumferential portion adjacent to a circumferential portion of drum 5 immediately behind and in optical alinement with the viewing aperture. Thus, each of the drums 7 is offcenter within drum 5, with the axis of drum 7 lying substantially on a radial line extending from the axis of drum 5 to the viewing aperture so that circumferential portions of drums 5 and 7 are closest together immediately behind the viewing aperture. For clarity of illustration, each drum 7 is herein represented as a shallow, pan-like component having one closed end and one open end. In practice, both ends of each drum 7 may be closed for greater rigidity and each such drum may comprise two pan-like parts, welded together. Each drum 7 is generally opaque but its circumference contains two diametrically opposite scanning slits 7 and two larger openings 7" disposed opposite each other approximately midway between the two scanning slits.

As is hereinafter more fully explained, each of the scanning drums 7 may at times be individually rotated relative to shaft 8 (as by stopping the drum while the shaft continues to rotate) so that each scanning drum can be set to various angular positions relative to the shaft, selectively, and may at times be connected to rotate in unison with shaft 8. In the particular embodiment here illustrated, shaft 8 and the drums 7 when rotating in unison therewith, is rotated counter-clockwise (as viewed in Fig. 2) at a constant angular velocity to, equal to one-half the angular velocity of drum 5. Consequently, for any given angular position of a drum 7 upon shaft 8, the same circumferential portion of drum 5 is momentarily alined with the viewing aperture as each of the scanning slits 7 passes through any selected, fixed position relative to the viewing aperture.

Each drum 7 has a rectangular hub 9 having two opposite polished surfaces 9' which form two parallel mirrors disposed to reflect light from openings 7 to respective ones of the scanning slits 7'. Each such hub rotates masses with its drum. A tubular lamp extends generally parallel to drum 5 and forms an elongated source of light. Lamp 10 is continuously lit during operation of the receiver. Typical light rays are represented in the drawing by broken lines 11. A cylindrical lens 12 and a mirror 13 direct converging rays of light through one of the larger openings 7" of each scanning drum whenever a scanning slit 7' of that drum is in optical alinement with the viewing aperture, in the manner indicated in the drawings. Because transparent drum 5 is generally light-transmissive, the characters marked thereon covering only a small fraction of its surface, light passes readily through drum 5 and openings 7" to the upper one of the two mirrors 9. The last-mentioned mirror then reflects such light toward the viewing aperture. Thus, each time that a scanning slit 7' comes into alinement with the viewing aperture, light passes through the scanning slit and through light-transmissive drum 5 to the translucent screen 3 of the viewing aperture.

The scanning slits 7 are narrow with respect to both the height of the viewing aperture and the height of the characters visibly marked upon drum 5. For example, the width of scanning slits 7' may be about one-tenth the height of the viewing aperture. Consequently, as each drum 7 rotates, each of its scanning slits 7' period ically passes through a position in optical alinement with the viewing aperture, and a ribbon of light periodically sweeps upward across each column of the viewing aperture. It will be noted that the light rays 11 are focused onto an area inside the circumference of drum 7 which is wider than the width of the scanning slits, and preferably is approximately equal in width to the height of the viewing aperture. This is done to insure that the scanning slit will receive light during its entire transit across the height of the viewing aperture, taking into account the fact that hub 9 rotates with drum 7, in consequence of which the light beam reflected from mirrors 9' moves at twice the angular velocity of the scanning drum.

In alinement with each of the scanning drums, there is a column of different characters visibly marked on and extending about the circumference of transparent drum 5. In the specific embodiment here illustrated there are sixty-four different characters in each column, which may comprise characters of any type desired to be displayed. For example, these characters may include upper-case and lower-case letters of the alphabet, numerals, punctuation marks, and a blank space, which for purposes of this invention may be considered a character.

Since scanning drum 7 contains two scanning slits 7' and is rotative at one-half the angular velocity of drum 5 it is apparent that the same character marked on drum 5 is moving past the viewing aperture each time that a ribbon of light is swept across the viewing aperture by a scanning slit. Therefore, the ribbon of light projects an optical image of the same character into the viewing aperture at each revolution of drum 5.

Considered in more detail, it will be noted that twice during each revolution of drum 7 a ribbon of light moves from the bottom to the top of the viewing aperture in the particular column under consideration. At the beginning of this transit, the ribbon of light is at the bottom of aperture 3. At this time the ribbon of light passes through the bottom of a character marked upside-down on drum 5 and consequently an optical image of the bottom of the character is projected into the bottom of the viewing aperture. As the ribbon of light moves upward in the viewing aperture the character marked on drum 5 moves upward at a faster speed and thereby successive portions of the same character are projected into different parts of the viewing aperture. As the ribbon of light reaches the top of the viewing aperture the top of the character marked on drum 5 is projected onto viewing screen 3, and thus the character, marked upside-down on drum 5, appears right-sideup on the viewing screen.

The size of the character projected onto the viewing" screen depends upon the size of the character marked upon drum 5, upon the relative circumferential velocities of drums 7 and 5, and upon whether or not the two drums rotate in the same direction or in opposite directions. The relative circumferential velocities of the two drums depend, of course, both upon their relative angular velocities and their relative radii.

In the particular embodiment herein illustrated and described, drums 5 and 7 rotate in the same direction, and the circumferential velocity of drum 5 is approximately three times as great as the circumferential velocity of drum 7. With this relation the characters projected onto viewing screen 3 are approximately one-half as high, and upside-down, with relation to the characters marked upon drum 5. Accordingly, characters are marked upon drum 5 in an upside-down position and of approximately twice the height desired for the display. Therefore, assuming that it is desired to display characters approximately the size of pica type, the circumference of drum 5 is made sufliciently large to accommodate 64 characters twice the height of pica type.

Furthermore, since one character projection occurs at each revolution of drum 5, drum 5 should be rotated at a sufliciently great rate that the successive projections occur periodically at intervals shorter than the persistence of vision so that the projected display appears to be continuous to the eyes of human observers. For example, drum 5 may be rotated at a speed of 30 revolutions per second.

Considered somewhat differently, the rotation of drum 5 is a periodic motion which causes the characters marked in each column on the drum to move periodically and in succession through a position in optical alinement with the viewing aperture. Similarly, the rotation of each scanning drum 7 is a periodic motion, which causes each of the scanning slits 7 to move periodically through a position in optical alinement with the scanning aperture and thereby causes a ribbon of light to sweep periodically from bottom to top of the viewing aperture in each column of the display. It is evident that the selection of any one of the characters marked around the circumference of drum 5 for projection into the viewing aperture depends upon the phase relation of these two periodic motions, which in turn depends upon the angular position of drum 7 relative to shaft 8. This phase relation can be adjusted by adjusting the angular position of drum 7 relative to shaft 8, in a manner hereinafter more fully explained. This is accomplished by means including the positioning units 14 and 15, and the reset bar 16, which are generally and somewhat schematically represented in Fig. 2 but are shown in more detail in Figs. 6 and 7 and are hereinafter more fully described.

It has already been explained that there are a plurality of the scanning drums 7 mounted in axial alinement upon shaft 8, one drum for each column or character of the display projected into the viewing aperture. There are small spaces between adjacent scanning drums, in consequence of which there are vertical bands or lines between columns in the display which do not receive periodic ribbons of light from the scanning slits. This tends to cause the appearance of dark, vertical lines between characters in the display, which may be objectionable. The appearance of such dark lines is prevented by illuminating the inter-character spaces with light supplied through the vertical slots 4. It will be noted that mirror 13 contains an opening 13. Certain of the light rays supplied by lamp 10 pass through opening 13', as is indicated in the drawings by typical rays 11', and this light is reflected by mirror 17 through the vertical slots 4 to illuminate the inter-character spaces in the viewing aperture.

The box 18 in the lower left portion of the case 1 represents a chassis which may be provided for various input and control components, if desired, or for other purposes.

Means for rotating the transparent drum and shaft 8 in synchronism is illustrated in Figs. 3 and 4. As has been explained, drum 5 is rotatively supported in any suitable bearings 6. For convenience of illustration a central portion of drum 5 has been cut away in- Fig. 4 to reduce the length of the figure and to permit the use of a larger and clearer scale. In practice, drum 5 may be of any desired length to accommodate as many columns of characters as it may be desired to display. Shaft 8 is rotatively supported in any suitable bearings 19. An electric motor continuously rotates a shaft 21 carrying two spur gears 22 and 23. Gear 22 engages a ring gear 24 attached to drum 5, as shown, and rotates drum 5 at a constant speed-say, 30 revolutions per second. Gear 23 engages a ring gear 25 attached to shaft 8 for rotating shaft 8 at a constant speed-say, l5 revolutions per second-equal to one-half the rotational speed of drum 5.

Shaft 21 also carries a spur gear 26 which is connected through an idler gear 27 to a driven gear 28. Gear 28 is connected through a friction clutch Z9 and a spring 30 to a shaft 31 so that rotation of gear 28 keeps spring 30 wound for applying a constant counter-clockwise (as viewed in Figs. 2 and 3) torque to shaft 31. Gear 28 also engages another gear 32 which is connected through a friction clutch 33 and spring 34 to a shaft 35, so that rotation of gear 32 keeps spring 34 wound for applying a continuous clockwise (as viewed in Figs. 2 and 3) torque to shaft 35. Shafts 31 and 35 form part of a triggering mechanism hereinafter more fully described.

By the means just described, there are applied to shafts 31 and 35 torques of sufficient magnitude to rotate these two shafts rapidly. Such rotations of shafts 31 and 35 are restrained by a pair of electromagnetically operated detent mechanisms. A wheel 36, attached to and rotative with shaft 31, has two diametrically opposite radial projections 36'. A bifurcated lever 37 is pivoted at 37' for oscillatory motion such that the forked end of the bifurcated lever engages alternate ones of the projections 36', as shown, to check the rotation of shaft 31. It is evident that each complete oscillation of lever 37 about its pivot 37 permits shaft 31 to rotate clockwise by one-half revolution responsive to the torque supplied by spring 30.

A spring 38 biases lever 37 to the position shown in the drawing. A solenoid 39, to which electric pulses are supplied at selected times as hereinafter explained, moves lever 37 against the bias of spring 38 each time that the solenoid is energized by an electric pulse. Consequently, responsive to each electric pulse supplied to solenoid 39, shaft 31 quickly rotates counter-clockwise through an angle of substantially 180 degrees.

A similar detent mechanism comprises a wheel 40 attached to and rotative with shaft 35, a bifurcated lever 41 pivoted at 41', a spring 42 biasing lever 41 to the position shown in the drawing, and a solenoid 43 for moving lever 41 against the bias of spring 42 at selected times. Thus, responsive to each electric pulse supplied to solenoid 43, in a manner hereinafter explained, shaft 55 quickly rotates clockwise through an angle of substantially 180 degrees responsive to the torque provided by spring 34.

The reset bar 16 is moved inward and outward relative to the scanning drums 7 by an electromagnetically operated reset mechanism. A lever 44, pivoted at 44', has one end connected to the reset bar 16 through a link, as shown, and has another end connected to a spring 45. The force of spring 45 biases reset bar 16 inward toward the scanning drums 7. At selected times, as is hereinafter explained, an electric pulse is supplied to a sole noid 46 which moves lever 44 against the bias of spring 45 and pulls reset bar 16 outward with respect to scanning drums 7.

With particular reference to Fig. 4, a portion of drum 5 has been cut away to show a plurality of the scanning drums 7 mounted on shaft 8 within drum 5. It will be noted that a plurality of gear-like wheels 47, having dentate or serrated peripheries, are disposed along shaft 8 between the scanning drums 7. The wheels 47 and drums 7 are arranged alternately along the shaft 8 so that there is a serrated wheel adjacent to each of the scanning drums. Wheels 47 are attached to and rotative with shaft 8, and are parts of means hereinafter described for selectively connecting each of the drums 7 to rotate in unison with shaft 8, or for disconnecting the drums so that the angular position of each drum can be individually adjusted relative to shaft 8, selectively.

A few of the characters visibly marked upon transparent drum 5 are shown in Fig. 4. It will be noted that these characters are arranged in rows extending lengthwise of the drum, and in columns extending circumferentially about the drum. In the specific embodiment herein described, each cohunn contains sixty-four diiferent characters including one blank space. As many columns as may be desired for the display are provided. As illustrated in the drawing, the same character appears in every column of any given row. With this arrangement a given character is always represented by the same received signal irrespective of the column in which that character is to be displayed. However, it is not necessary that this be the case. As will become evident as the description proceeds, a given received signal will select for display in a particular column whatever character is marked in that column at a particular row on drum 5. If different characters are marked in the same row of dilferent columns, then difierent characters will be represented by similar received signals at different columns of the line display. This may be desirable, for example, when coded signals are employed for secrecy purposes.

The characters may be printed or otherwise visibly marked directly upon the surface of drum 5. Alternatively, the characters may be marked on a removable film which can be attached to drum 5 by any appropriate fastening means. The use of such a removable film has obvious advantages when coded messages are to be transmitted for secrecy reasons, since the code can be changed at will by substituting different films on which the char acters are differently arranged.

Still referring to Fig. 4, an optical commuter drum 5' is attached to the right end of drum 5 and rotates therewith. Extending circumferentially around the commuter drum illustrated, there are six pairs of side-by-side optical tracks, each comprising a plurality of lengthwise sections. Alternate sections of each track are light-transmissive (e.g., transparent), and other alternate ones are nontransmissive (e.g., opaque). In the drawing, the transparent sections of each track are shown in white and the opaque sections are shown in black. As is hereinafter more fully explained, light is transmitted from a source to a light-sensitive transducer via transmissive sections, and not by non-transmissive sections.

A first pair of such tracks is shown at 48 and 48'. Each of these tracks is divided into two semi-circular lengthwise sections, one of which is light-transmissive or transparent, and the other of which is non-transmissive or opaque. It wil be noted that the opaque section of track 48 is beside and adjacent to the transparent section of track 48, and vice versa. Thus, with respect to any fixed observation point, the transmission of light is periodically commuted back and forth between tracks 48 and 48 as drum 5 rotates.

A second pair of such tracks is illustrated at 49 and 4?. Tracks 49 and 49' are generally similar to tracks 48 and 48' except that each of the tracks 49 and 49 is divided into four lengthwise sections, each extending over substantially degrees of the circumference of the commuter drum. In each track, transparent and opaque sections are disposed alternately around the circhmfe'rence of the drum, and in each pair of tracks an opaque section of one track lies beside a transparent section of the other track, and vice versa. Similarly, a third pair of tracks is shown at 50 and 50', a fourth pair of tracks is shown at 51 and 51, a fifth pair of tracks is shown at 52 and 52, and a sixth pair of tracks is shown at 53 and 53'. Each pair of tracks is divided into twice as many lengthwise sections as the preceding pair of tracks. Thus, each of the tracks 53 and 53' is divided into sixty-four lengthwise sections, with transparent and opaque sections disposed alternately in each track, and with the opaque sections of each track disposed beside the transparent sections of the other track of the same pair, and vice versa.

Those skilled in the art will recognize that the arrangement illustrated and described is a binary digitalizer, whereby sixty-four difierent angular positions of drum can be identified by a six-digit binary number, wherein the value of each binary digit is indicated by the commuting of light from one track to the other of a pair of tracks. For simplicity and clarity of illustration, the twelve tracks have been shown as lying immediately adjacent to one another. In actual practice, guard bands, continuous opaque rings, may be provided between tracks to insure against interference between light signals transmitted by the various tracks.

Fig. 5 best illustrates the manner in which scanning drums 7 and serrated wheels 47 are assembled on shaft 8. As illustrated, shaft 8 is of square cross section, and wheel 47 contains a square central opening 47' into which shaft 8 fits snugly so that wheel 47 always rotates in unison with shaft 8. The hub 9 of scanning drum 7 contains a circular opening which fits rotatively upon a sleeve 54 mounted upon shaft 8. Washers 55 are placed on the shaft between each drum 7 and the two adjacent serrated wheels 47 to facilitate rotation of the drums relative to shaft 8 at selected times, as herein explained.

Fig. 6 illustrates in more detail two of the positioning units 14 and which are employed for adjusting the angular positions of scanning drums 7 relative to shaft 8. In the embodiment here illustrated there are two pluralities of such positioning units: one plurality, identified by reference number 14 controls the positioning of alternate ones of drums 7; while the other plurality, identified by reference number 15 controls the positioning of the other alternate ones of drums 7. Thus, a plurality of identical positioning units 14 are alined along support rods 56, with one unit 14 adjacent to each alternate one of the scanning drums 7. Sleeves 57 act as spacers be tween adjacent ones of the positioning units 14. Similarly, a plurality of positioning units 15 are alined along support rods 58, with one unit 15 adjacent to each of the other alternate ones of scanning drums 7. Sleeves 59 act as spacers between units 15.

Fig. 7 is a fragmentary section detail taken through two of the units 15. As illustrated in Figs. 6 and 7, each of the units 14 comprises a supporting plate 14' which may, if so desired, take the form of a hollow box instead of a flat plate as illustrated. Similarly, each of the units 15 comprises a supporting plate 15' which may, if so desired, take the form of a hollow box instead of a flat plate. Shaft 31 passes through all of the positioning units 14, and shaft 35 passes through all of the positioning units 15.

With particular reference to Figs. 6 and 7, a locking arm 60 is rotatively mounted on a rivet 61 attached to plate 15'. Shaft 35 extends through a slot 60 of arm 60, whereby arm 66 is permitted to swing through a small angle about its rotative mounting on rivet 61. A spring 62 biases arm 60 upward as viewed in Fig. 6.

A sear 63 is rotatively mounted on a rivet 64 attached to arm 60 at the position shown. A spring 65 biases sear 63 toward the position 63 indicated by broken lines in Fig. 6; but in the position of the parts shown in Fig. 6, sear 63 is held in the full-line position illustrated by abutment of the lower portion of the sear against shaft 35. Also, in the position of the parts shown in Fig. 6, a portion of scar -63 abuts on a shoulder of reset bar 16, and thereby locking arm 60 is held in the position illustrated against the bias of spring 62.

A hammer 66 and a tripping lever 67 are fixedly attached to a rotative shaft 66 which extends through a lower portion of arm 60, as shown. A spring '68 and a link 69, disposed and arranged as shown, provide a snapaction motion of hammer 66 from the cocked position shown to a tripped position, as hereinafter described.

A pawl 70 and a pawl lever 71 are fixedly attached to a rotative shaft 72 which extends through scanning drum 7 near the trailing edge of one of the openings 7. Pawl 70 is disposed to engage the teeth of the serrated wheel 47 adjacent to (immediately behind as viewed in Fig. 6) scanning drum 7. A spring 73 biases the pawl and pawl lever toward the position illustrated, where pawl 70 and wheel 47 are in engagement. In this position of the parts, scanning drum 7 is connected to wheel 47 through pawl 70 so that scanning drum 7 rotates in unison with wheel 47 and shaft 8.

It will be noted in Figs. 6 and 7 that tripping lever 67 extends downward into a space between adjacent ones of drums 7. A tripping pin 74 is attached to drum 7 and extends outward from the drum a sufficient distance to engage tripping lever 67 as drum 7 rotates. Thus, the engagement of tripping pin 74 with tripping lever 67 at selected times as is hereinafter more fully explained, trips the hammer mechanism from a cocked position to a tripped position and causes hammer 66 to strike pawl lever 71, which rotates pawl lever 71 and shaft 72 to raise pawl 70 out of engagement with serrated wheel 47, whereby drum 7 is disconnected from wheel 47 and the rotative shaft 8.

The hammer mechanism also comprises a cocking cam 67', which may be formed as a part of tripping lever 67, as shown. At selected times this cocking cam engages a cocking pin 75, mounted on plate 15, for cocking the hammer mechanism, as is hereinafter more fully explained. Also, there is attached to the back side (as viewed in Fig. 6) of each arm 60 a pin 76 which extends through a slot 15" in plate 15 over the sear 63 of the next positioning unit.

The several parts of positioning unit 14 are substantially the same as corresponding parts of positioning unit 15, except for such minor and obvious modifications as are expedient because of the fact that units 14 and 15 are disposed on opposite sides of reset bar 16 and are oppositely oriented with respect to the direction of rotation of drum 7. As hereinbefore explained, units 14 are adjacent to and associated with alternate ones of the drum 7, whereas units 15 are adjacent to and associated with other alternate ones of the drum 7. Thus, with reference to Fig. 6 the unit 15 illustrated is operatively associated with the scanning drum 7 that is shown in Fig. 6, whereas unit 14 illustrated is operatively associated with the next scanning drum 7 lying immediately behind the scanning drum shown in Fig. 6.

With particular reference to Fig. 6 and the positioning unit 15 therein illustrated, the operation of a typical positioning unit will now be described. Trigger shaft 35, locking arm 60, sear 63, pin 76 extending over sear 63 from an adjacent positioning unit, and reset bar 16 are parts of a locking mechanism that is movable selectively to two positions, herein called the set position and the released position. The set position is illustrated: the released position is assumed when sear 63 is released from its engagement with reset bar 16, as is hereinafter explained, and arm 60 moves upward under the influence of spring 62.

Attached to and forming a part of the locking mechanism, there is a hammer mechanism comprising a hammer 66, tripping lever 67, spring 68, link 69 and cocking cam 67'. It is evident that the entire hammer mechani'sm moves upward with arm 60 when the locking mechanism moves to its released position, and at such time tripping lever 67 is withdrawn from the space between scanning drums 7. In addition, while the locking mechanism remains in the set position illustrated, the hammer mechanism may have either a cocked position or a tripped position. In the positions of the parts illustrated in Fig. 6, locking arm 60 is in its set position and hammer 66 is in its cocked position. Therefore, it may be said that the hammer mechanism comprising hammer 66 is in a cocked and set position.

To further illustrate the different positions which the parts may take, Fig. 6 shows the positioning unit 14 with its locking arm 77 in the set position and its hammer mechanism 73 in the tripped position. In the tripped position, it will be noted that hammer 78 bears down against the top of the pawl lever 79 of the next scanning drum (immediately behind the drum 7 illustrated in Fig. 6) and that this raises the pawl 80 of the next drum out of engagement with the corresponding serrated wheel 47. The released position of arm 77 is indicated by broken lines 77.

As illustrated in Fig. 6 the positioning unit 15 is in the cocked and set position. Pawl 70 is in engagement with serrated wheel 47 so that drum 7 is connected to wheel 47 and rotates in unison With shaft 8. As drum 7 rotates, tripping pin 74 moves into engagement with tripping lever 67 and rotates this tripping lever until the force supplied by spring 68 through link 69 moves to the left of shaft 66, whereupon the spring force continues the rotation of the hammer mechanism and snaps hammer 66 down onto the top of pawl lever 71. This raises pawl 76 out of engagement with serrated wheel 47 and almost simultaneously the trailing edge of opening 7" abuts against hammer 66 so that the rotation of drum 7 is quickly stopped in a reference angular position of the scanning drums. It is evident that all of the scanning drums can thus be quickly brought to a stop in fixed reference angular positions simply by resetting all of the several hammer mechanisms to the cooked and set position.

Now assume that shaft 35 is rotated clockwise (as viewed in Fig. 6) through an angle of approximately 180 degrees. It will be noted that shaft 35 is provided with a slot 35 which extends approximately half way through the shaft in alinement with sear 63. If the preceding unit 15 is still in a set position, pin 76 from the preceding unit closely overlies sear 63 and no substantial motion of the sear is possible. However, if the preceding unit has previously been moved to the released position, pin 76 will have moved upward to the broken-line position shown at 76. In this event as shaft 35 rotates, the lower portion of sear 63 is able to move into the slot of the trigger shaft, whereupon sear 63 rotates to the broken-line position 63 and clears the reset bar 16. This permits arm 60 to move, with a rapid snapaction, to its released position under the influence of spring 62.

As arm 60 moves to its released position the hammer mechanism, including hammer 66 and tripping lever 67, moves out of engagement with drum 7. Pawl 70 then quickly moves into engagement with serrated wheel 47 under the influence of spring 73 and again connects drum 7 for rotation in unison with shaft 8. It is thus apparent that the rotation of drum 7 can be restarted at diiferent epochs in the rotational cycle of shaft 8, with drum 7 in various angular positions relative to shaft 8, selectively, controlled by the time of rotation of trigger shaft 35.

Furthermore, as arm 60 moves to its released position, cocking cam 67 engages cocking pin 75 which automatically rotates the hammer mechanism back to its cocked position. Thus the hammer mechanism is automatically cocked as the locking mechanism moves to the released position.

With particular reference to Fig. 7, it will be noted that alternate ones of the slots 35' in shaft 35 are disposed approximately degrees from the other alternate ones of slots 35. Thus, each rotation of shaft 35 tends to release approximately one-half of the set positioning units 15. However, the pins 76 prevent the release of any positioning unit until the immediately preceding unit has been released. Therefore, successive rotations of shaft 35 through angles of approximately 180 degrees release successive ones of the set positioning units, one unit being released at each 180 degree rotation of shaft 35.

As has already been explained in connection with Fig. 3, shaft 35 rotates through an angle of approximately 180 degrees responsive to each electric pulse supplied to solenoid 43. Thus, each successive electric pulse supplied to solenoid 43 releases a successive one of the positioning units 15, and thus re-starts the rotation of a successive one of the alternate scanning drums 7 controlled by positioning units 15. In this way the timing of the electric pulses supplied to solenoid 43 controls the angular positions of alternate ones of scanning drums 7 upon shaft 8.

Similarly, the timing of electric pulses supplied to solenoid 39 controls the angular positions of the other alternate ones of scanning drums 7 upon shaft 8. Consequently, successive electric pulses, generally supplied to solenoids 39 and 43 alternately, successively re-start the rotation of successive scanning drums 7 in adjustable phase relation to the rotation of drum 5 and by this means any one of the characters marked upon drum 5 in each column can be selected for display within viewing aperture 3.

Once the scanning drums have been set into rotation they continue rotating in the same relative phase relation until the apparatus is reset as hereinafter explained. Thus, a line of characters selected for display can be displayed for as long a time as may be desired. In other words, the several scanning drums rotating in adjustable phase relation to the rotation of drum 5 constitute an information-storage or memory device capable of storing or remembering the information represented by a whole line of characters.

To reset the apparatus a pulse of current is supplied to reset solenoid 46, which then moves reset bar 16 into the position 16' represented by broken lines in Fig. 6. As reset bar moves outward relative to drums 7 each sear rotates again its spring bias, as is indicated in Fig. 6 by the broken line position 81' of sear 81 of positioning unit 14. Thus, the two inwardly facing shoulders of reset bar 16 pass over the outwardly facing shoulders of the several scars, and the scars then snap into positions underlying the reset bar under the influence of their biasing springs.

Upon termination of the pulse of current supplied to solenoid 46, spring 45 returns reset bar 16 to its initial position, represented by full lines in Fig. 6. As the reset bar returns to its initial position, the several sears and the locking arms to which they are attached are pulled inward toward the scanning drums by the reset bar. Thus, all of the positioning units are simultaneously reset to their set position. All of the hammer mechanisms have previously been cocked during release of the positioning units, and consequently all units are now in the set and cocked position. As each scanning drum 7 approaches its reference angular position its tripping pin 74 strikes the corresponding tripping lever 67, which trips the adjacent hammer mechanism and stops that scanning drum in its reference angular position. Thus, all of the scanning drums are stopped in reference positions almost simultaneously and the display disappears from the viewing aperture. Operation may then proceed, with pulses supplied to solenoids 3? and 43 for re-starting successive ones of the scanning drums in adjustable phase relation to drum 5 for displaying a new line of characters.

As hereinbefore noted, the selection of a character to be displayed in a particular column of the viewing aperture is determined by the timing of an electric pulse supplied to solenoid 39 or solenoid 43 relative to a rotational cycle of drum 5. Consequently, in order to select a particular character for display responsive to a received signal, it is necessary to provide a periodic signal representative of the instantaneous angular position of drum 5, to compare this periodic signal with a received signal, and to supply solenoids 39 and 43, selectively, with an electric pulse when a desired relation is reached between the two signals so compared. Periodic signals representative of the instantaneous angular position of drum may be obtained by directing light through commuter drum 5, illustrated in Fig. 4 and hereinbefore described.

Referring to Fig. 8, commuter drum 5' rotates counterclockwise at a substantially constant angular velocity. Within the drum a continuously lit lamp 82 and a reflector 83 supply a band of light to fixed reference positions intercepted by each of the twelve optical tracks of the commuter drum. As drum 5 rotates, light-transmissive and non-transmissive sections of each track pass alternately through the reference positions so that the transmission of light is periodically commuted from one track to the other of each pair of tracks. At any given instant, six beams of light pass from lamp 82 through light-transmissive sections of six tracks, and as the drum 5 rotates the transmission of light shifts from one track to another in sixty-four different combinations representative of sixty-four different angular positions of drum 5.

An electro-optical switch 84, hereinafter described, may transmit light from each track, or not transmit such light, selectively, under the control of a received signal. Any light which passes through the optical switch 34- reaches a phototube 85, or other light-sensitive transducer At a selected epoch in the rotational cycle of drum 5 determined by the setting of optical switch 84 under the control of a received signal, the transmission of light to phototube 85 is completely out off, and thereupon the phototube supplies an electric pulse to solenoid 39.

A similar arrangement is provided for supplying electric pulses to solenoid 43. This comprises a continuously lit lamp 86, a reflector 87, an electro-optical switch 88, and a phototube 89. Thus, two electro-optical comparators are provided, each of which compares two entities: a received signal, and a periodic signal .representative of the instantaneous angular position of drum 5. One of these electro-optical comparators energizes solenoid 39 at selected times for adjusting the phase relations between the rotation of alternate scanning drums 7 and the rota tion of drum 5, and the other of the two electro-optical comparators energizes solenoid 43 at selected times for adjusting the phase relations between the rotations of other alternate ones of scanning drums 7 and the rotation of drum 5.

Because positioning units '14 and positioning units 15 stop respective ones of the scanning drums 7 at slightly difierent reference positions, as is evident from Fig. 6 of the drawings, the two electro-optical comparators are placed at somewhat different angular positions in relation to drum 5. However, the angular spacing between the two electro-optical comparators for this purpose is fairly small and may leave the two comparators inconveniently close together.

More space between the comparators can be obtained simply by moving one of the two comparators an additional 180 degrees around drum 5. With the arrangement of commuter tracks illustrated and described, this 180 degree movement of a comparator simply reverses the light signals. received by that comparator through the commuter tracks. Compensation for this reversal of the light signals is easily accomplished by a minor modification of the optical switch 88, such as a reversal of the masking elements within the switch, hereinafter described, or a reversal of the electrical windings of the switch. If desired, both of the two electro-optical corn parators may be made adjustable in position relative to commuter drum 5 for adjusting the timing of pulses supplied to relays 39 and 43 to achieve proper operation of the receiver. One of the two comparators may be contained within portion of case 1 (see Fig. 1) and the other may be contained within the ample space available within case 1 to the rear of the rotating drums.

The construction of the electro-optical comparators is shown in more detail in Figs. 9, 10 and 11. Since the two comparators are essentially identical, only one is illustrated in detail. As has already been explained, light passes through light-transmissive sections of the six pairs of optical tracks carried by commuter drum 5'. Such light may or may not pass through the electro-optical switch 84-, depending jointly upon the angular position of drum 5 and the setting of the relay by a received signal. Such light as is transmitted through relay 84 is received by a phototube 85.

Switch 84 has a transparent bottom 9-1, which may be a plate of glass or clear plastic. Opaque walls 92 define a light passageway or chimney through the electrooptical switch so that only that light which passes through a narrow reference position alined with each optical track can reach phototube 85. A small condensing lens 93 may be placed Within the light chimney for focusing the light more eifectively onto the cathode of the phototube. The opening at the bottom of the light chimney defined by walls 92 is sufliciently narrow that the shortest opaque section of any of the twelve tracks on drum 5 will completely cut off light from that track to phototube 35. Thus, as drum 5' rotates each of the twelve optical tracks alternately supplies and fails to supply light to a reference position at the bottom of switch 84.

Between transparent plate 91 and the bottom of chimney walls 92 there are six masking elements identified in the drawing by reference numbers 94 through 99. There is one of such masking elements in ailnement with each pair of optical tracks on commuting drum 5'. Each of these masking elements is substantially opaque but contains two light-transmissive apertures and 101, disposed in a diagonal, staggered manner, as shown. The apertures 100 and 101 are alined with respective ones of the two optical tracks comprising a respective pair of the six pairs of such tracks on commuter drum 5'. Thus, light from the first track of one pair can reach the light chimney only by passing through aperture tilt), and light from the other track of the same pair can reach the same light chimney only by passing through aperture 101.

Furthermore, each masking element individually may be moved lengthwise to either of two positions. In one such position, aperture 100 is in alinement with the light chimney while aperture 101 is not, so that light from the first track only of the corresponding pair on drum 5 can reach phototube 85. In the other position of the masking element, aperture 101 is alined with the light chimney while aperture 100 is not, so that light from the second one only of the corresponding pair of tracks on drum 5 can reach phototube 85.

It is evident that there are sixty-four different combinations of positions of the six masking elements, and that for each such combination of positions there is a different one of sixty-four different angular positions of drum 5 at which no light reaches phototube 85. Since phototube 85 supplies an electric pulse to solenoid 39 substantially at the instant when light to the phototube is completely cut off, solenoid 39 can be energized at any one of sixty-four different epochs, selectively, in the rotational cycle of drum 5.

Each of the masking elements 94 through 99 is connected to a respective one of six magnetic armatures, identified in the drawings by reference numbers 10-2 through 107. Each of these siX armatures is permanently magnetized, with like poles (represented by the letter N).

at opposite ends of the armature, and an opposite pole (represented by the letter S) at the center of the armature.

Six electromagnets, represented by reference numbers 108 through 113, are adjacent to respective ones of the six magnetic arinaturcs. Each of the six electromagnets can be magnetized in either magnetic polarity, selectively, as by applying to its winding either a positive pulse or a negative pulse, selectively. Alternatively, each electromagnet may be provided with a split winding such that current pulses of like polarity can be applied to either half of the winding, selectively, for magnetizing the electromagnet in either polarity, selectively.

It is evident that magnetization of any one of these six elec-tromagnets in one polarity will cause the adjacent armature to move a corresponding one of the six masking elements to one of its two positions, and that magnetization of the same electromagnet in the opposite polarity will cause the same armature to move the same masking element to the other of its two positions. To insure that a masking elemnet will remain in the same position between pulses applied to its control electro magnet, any suitable holding means may be provided, such as small dimples in the masking elements cooperating with ridges in plate 91, as illustrated.

Reference is now made to the circuit diagram illustrated in Fig. 12. Assume that successive characters to be displayed by the receiver are represented by successive groups of electric pulses received through wires 114 through 121 Each group of pulses, representing a single character, comprises six pulses, each of posi* tive or negative polarity, selectively, received substan tially simultaneously through wires 114 through 119, and a seventh timing or control pulse, illustratively of positive polarity, received through wire 12%).

A seven-pole, double-throw relay is illustratively provided with two windings 121 and 122. Energization of winding 121 with a pulse of current pulls this relay to a first position wherein the relay connects wires 114 through 119 to respective ones of electromagnets 1% through 113 of electro-optical switch 84, and connects wire 12% to relay winding 122. Energization of winding 122 with a pulse of current throws the same relay to a second position wherein wires 114 through 119 are connected to respective ones of the six electromagnets within electro-optical switch 88 and wire 120 is connected to relay winding 121.

Capacitors 123 and 124 may be connected in parallel with windings 121 and 122, respectively, for briefly delaying the relay action, or any other means may be provided to insure an adequate delay in relay action for reliable operation of the relay fromone position to the other responsive to each pulse received through w-i-re 120. Since each electric pulse supplied through wire 12G switches the seven-pole relay from one to the other of its two positions, alternate groups of the six pulses supplied through wires 114 through 119 are supplied to electro-optical switch S4, and the other alternate groups of such pulses are supplied to electro-optical switch 38. Thus, information representative of one character to be displayed is set up in switch 84, informa tion representative of the next character to be displayed is set up in switch 83, then information representative of the next character is set up in switch 84, etc.

Photocell S3 is connected in any suitable supply cir cuit, such as that illustrated comprising resistors 125, 126 and 127, and diode rectifier 128, connected as shown, whereby a positive pulse is provided at the an ode of phototube 85 each time that the light to photo tube 85 is cut oil. Terminal 12h represents any suit able source of positive direct voltage. Similarly, phototube 89 is connected in a circuit, illustrativcly compris ing resistors 139, 131 and 132, and diode rectifier 133, for providing a positive voltage pulse at the anode of phototube 89 whenever the light to this phototube is cut 16 oif. Terminal 134 represents any suitable source of positive direct voltage.

Positive pulses supplied at the anode of phototube are amplified by an amplifier 135 and supplied to a relay contact 136. A relay winding 137 for closing contact 136 is connected in parallel with relay winding 122, so that contact 136 is closed immediately following each group of pulses supplied to electro-optical switch 84. When drum 5 reaches an angular position corresponding to the information set up in switch 34, the light to phototube 85 is suddenly cut oil, as herein before explained. The voltage pulse then provided at the anode of phototube $5 is amplified by amplifier 135 and supplied through closed relay contact 136 to solenoid 3? and relay winding 138, which are connected in series as shown. A pulse of current flows through solenoid 39 and one of the scanning drums 7 is set into motion, in the manner hereinbefore explained, for displaying a character selected by a signal stored in switch 84. Energization of relay winding 133 is delayed brieflyby a capacitor 139 connected in parallel therewith. As soon as capacitor 139 has become sufiiciently charged winding 138 is energized and this opens relay contact 136 so that solenoid 39 cannot be energized again until another group of received pulses has been supplied to electro-optical switch 84.

The next group of received pulses is supplied to electro-optical switch 88, which sets up in this switch information corresponding to the next character to be displayed. A timing pulse supplied through line energizes relay winding 121, as hereinbefore explained, and simultaneously energizes a relay winding 140 which closes a relay contact 141. When drum 5 reaches an angular position corresponding to the information now set up in electro-optical switch 88 the light to phototube 89 is suddenly cut off, as hereinbefore explained. This provides an electric pulse which is amplified by an amplifier 142 and supplied through the closed relay contact 141 to solenoid 13 and relay winding 143, which are connected in series as shown. A pulse of current flows through solenoid 43 and sets a seaming drum '7 into rotation, as hereinbefore explained, for displaying a character corresponding to the information stored in switch 88. Encrgization of relay winding 143 is delayed by a capacitor 144 connected in parallel therewith. As soon as capacitor 144 has charged sufiiciently, relay winding 143 is energized and opens contact 141 so that solenoid 43 cannot be energized again until the next group of pulses is received by electro-optical switch 83.

While electromechanical relays have been specifically illustrated and described for the purpose of simplifying and clarifying the description, in practice highspeed electronic and magnetic switching devices (many forms of which are known to those skilled in the art) may be substituted for the relays.

The operation continues in the manner just described, with successive groups of received signals being supplied to electro- optical switches 84 and 88 alternately. Each of the switches 84 and 88 stores the information represented by one group of pulses until another group of pulses is supplied to the same switch. At selected epochs in the rotational cycle of drum 5, controlled by the received information temporarily stored in switch 84, phototube 85 and amplifier supply an electric pulse to solenoid 39 for starting the rotation of a scanning drum 7 in selected phase relation to the rotation of drum 5 for displaying a selected character. Similarly, at selected epochs in the rotational cycle of drum 5, controlled by the received information temporarily stored in electro-optical switch 88, phototube 89 and amplifier 142 supply an electric pulse to solenoid 43 for starting the rotation of another scanning drum 7 for displaying another character. Thus, successive received signals control the angular positioning of successive drums 7 on shaft 8, and such positioning of each drum controls the 17 display of a selected character within viewing aperture 3. The relative positions of the scanning drums store information represented by a whole line of characters, and the Whole line is displayed substantially continuously, as seen by a human observer, until the receiver is reset for receiving the next line of information.

Resetting may be accomplished by any means for supplying an electric pulse through wire 145 to reset solenoid 46, which then operates a reset bar 16 for stopping all of the drums 7 in reference positions, as hereinbefore explained.

It will be appreciated that numerous changes and modifications may be made in the illustrative embodiments herein described, and that the following claims are intended to cover all changes and modifications within the true spirit and scope of this invention.

What is claimed is:

l. Signal-responsive apparatus for displaying different characters selectively, comprising a member having a plurality of different characters visibly marked thereon, means for imparting to said member a periodic motion such that each of said characters in succession passes through a common position, scanning means for providing a ribbon of light having a periodic motion in a direction substantially parallel to its thickness, said ribbon being composed of rays that intersect said member and sweep periodically across said common position, means for synchronizing the periodic motions of said member and said ribbon so that said rays sweep across a selected one of said characters at the same epoch in successive cycles of the motion of said member, whereby a selected character is displayed at said common position, and signalresponsive means for varying the phase relation between the periodic motions of said member and said ribbon so that each of said difierent characters, selectively, can be so displayed.

2. Apparatus as defined in claim 1, wherein said scanning means comprises a rotative, generally opaque drum having therein a longitudinal scanning slit that is pervious to light and is narrow relative to the heights of said characters, and also comprises a source of light disposed to supply light through said slit toward said common position.

3. Apparatus as defined in claim 2, wherein said drum has therein an opening that is pervious to light and is Wide relative to said scanning slit, there being a mirror within and rotative with said drum, said mirror being disposed to reflect light from said opening to said slit, said source being disposed to supply light through said opening to said mirror when said slit is in substantial alinement with said common position.

4. Apparatus as defined in claim 2, wherein said member is a rotative, generally light-transmissive drum having said plurality of different characters disposed in a column extending circumferentially about said drum, said opaque drum being of smaller diameter than, inside of, and axially parallel to said light-transmissive drum, said opaque drum being longitudinally in alinement with said column and axially off-center within the larger drum so that the circumferences of the two drums are most closely adjacent along a common radius extending approximately through said common position.

5. Apparatus as defined in claim 1, wherein said signal-responsive means comprises means for stopping the periodic motion of said ribbon at a fixed epoch in its cycle while continuing the periodic motion of said member, means for providing a periodic signal representative of the instantaneous position of said member, means for receiving and holding a signal representative of a character selected to be displayed, and means jointly responsive to the signal so held and .to said periodic signal for restarting the periodic motion of said ribbon at different epochs, selectively, in the periodic motion of said member, whereby each of said different characters, selectively, is disi8 played responsive to the receipt of a signal representative of that character.

6. Signal-responsive apparatus for displaying a line of selectively diflerent characters, comprising a movable member, means for imparting a periodic motion to said member, a plurality of individually movable components, driving means synchronized with the periodic motion of said member, a plurality of devices each operable to engaged and disengaged positions, selectively, each of said devices being associated with a respective one of said components and serving in its engaged position to con nect that component to said driving means in selective time-positional relation thereto, said driving means imparting to each of the so-connected components a periodic motion synchronized with the periodic motion of said member, the phase relation between said periodic motions depending upon the time-positionalrelation of such com- .ponent to said driving means, means for displaying a line of characters wherein each character may be any one of a plurality of different characters, selectively, depending upon the phase relation between the periodic motion of a respective one of said components and the periodic motion of said member, means for operating said devices to their disengaged positions and stopping the periodic motion of each of said components at a fixed epoch in its cycle while continuing the periodic mo tion of said member, repetitively operable means efiective at each operation thereof to operate a successive one of said devices to its engaged position for re-starting the periodic motion of a successive one of said components in selective phase relation to the periodic motion of said member, means for providing a periodic signal representative of the instantaneous position of said member, means for receiving and temporarily holding each of a succession of received signals, and means jointly responsive to the signal so held and to said periodic signal for operating said repetitively operable means once following the receipt of each received signal, at different epochs, selectively, in the periodic motion of said member, whereby each of said components in succession is set into periodic motion in a selected phase relation to the periodic motion of said member, so that successive received signals determine successive characters in a line of displayed characters.

7. Apparatus as defined in claim 6, wherein said member is visibly marked with a plurality of characters arranged in a plurality of lines and columns, each column comprising a plurality of different characters, the periodic motion imparted to said member being in a direction substantially parallel to said columns so that each of said lines in succession passes through a common position,

said individually movable components being in optical alinement with said common ones of said columns.

8. Apparatus as defined in claim 7, wherein said member is a rotative, generally light-transmissive drum with position and with respective said columns extending circumferentially and said lines extending longitudinally thereon; and said individually movable components comprise a plurality of axially, alined, individually rotative, generally opaque drums eachv having therein a longitudinal scanning slit that is pervious to light and is narrow relative to the heights of said characters, said generally opaque drums being of smaller diameter than, within, and axially parallel to said lighttransmissive drum.

9. Apparatus as defined in claim 8, wherein each of opening to said slit, there being a of said mirrors when each of said slits is in substantial ;optical alinement with said common position.

10. Apparatus as defined in claim 6, wherein said individually movable components comprise a plurality of axially alined, rotative drums; said driving means comprises a rotative shaft extending axially through said drums, and a plurality of serrated discs interposed between respective pairs of said drums, said discs being connected to said shaft for rotation in unison therewith; and said devices comprise a plurality of pawls, one attached to each of said drums for rotation in unison therewith, each of said pawls being movable selectively into and out of engagement with a respective one of said serrated discs, and a plurality of springs biasing respective ones of said pawls into engagement with respective ones of said discs.

511. Apparatus for receiving and storing a succession of signals, comprising a plurality of individually movable components, driving means operable to produce a periodic motion, a plurality of devices each operable to engaged and disengaged positions, selectively, each of said devices being associated with a respective one of said components and serving in its engaged position to connect that component to said driving means in selective time-positional relation thereto, said driving means imparting to each of the so-connected components a synchronized periodic motion having a relative phase that depends upon the time-positional relation of such component to said driving means, reset means for operating said devices to their disengaged positions and stopping the periodic motion of each of said components at a fixed epoch in its cycle while continuing the operation of said driving means, repetitively operable means eifective at each operation thereof to operate a successive one of said devices to its engaged position for re-starting the periodic motion of a successive one of said components in selective relative phase, means for providing a periodic signal synchronized with the operation of said driving means, means for receiving and temporarily holding each of a succession of received signals, and means jointly responsive to the signal so held and to said periodic signal for operating said repetitively operable means once following the receipt of each received signal, at different epochs of said periodic signal, selectively, under the control of such received signal, whereby each of said components in succession is set into periodic motion with a relative phase that is determined by and is representative of a successive one of said received signals.

12. Apparatus as defined in claim ll, wherein said components are axially alined and individually rotative; said driving means comprises a rotative shaft extending axially through said components, and a plurality of serrated discs interposed between respective pairs of said components so that there is one of said discs beside each of said components, said discs being connected to said shaft for rotation in unison therewith; and said devices comprise a plurality of pawls, one attached to each of said components for rotation in unison therewith, each of said pawls being movable selectively into and out of engagement with a respective one of said serrated discs, and a plurality of springs, one acting upon each of said pawls, biasing respective ones of said pawls into engagement with respective one of said discs.

7 13. Apparatus as defined in claim 12, wherein said reset means comprises a plurality of hammer mechanisms, one adjacent to each of said rotative components, each of said hammer mechanisms being operable to a cocked and set position and to a tripped position, selectively, means for moving said hammer mechanisms totheir cocked and set positions, each of said components having thereon a part that trips the adjacent hammer mechanism from its cocked and set position to its tripped position as such component approaches a fixed angular position, the so-tripped hammer mechanism having a part that then strikes and moves the pawl attached to the adjae cent rotative component out of engagement with the respective serrated disc, the tripped mechanism locking and holding the adjacent rotative component in said fixed angular position, whereby all of said rotative components are individually stopped in fixed angular positions by said reset means. I

14. Apparatus as defined in claim 11, wherein said reset means comprises a plurality of locking mechanisms, one adjacent to each of said movable components, each of said locking mechanisms being movable to a set position and to a released position, selectively, each of said locking mechanisms in its set position stopping the adj acent component and moving said device attached thereto to its disengaged position as said adjacent component reaches a fixed position in its periodic motion, each of said locking mechanisms in its released position allowing said device attached to the adjacent component to return to its engaged position and permitting said adjacent component to resume and to continue its periodic motion, a plurality of springs, one for each of said locking mechanisms, biasing respective ones of said locking mechanisms to their released positions, and means for moving said locking mechanisms to their set positions against the bias of said springs; and said repetitively operable means comprises a trigger movable to two positions alternately, said trigger in one of its two positions being effective to retain alternate ones of said locking mechanisms in their set positions, said trigger in the other of its two positions being effective to retain the other alternate ones of said locking mechanisms in their set positions, so that each operation of said trigger from one to the other of its two positions tends to release approximately one-half of the locking mechanisms that are then in their set positions, each of said locking mechanisms having a part which in the set position of that locking mechanism prevents such release of the next successive locking mechanism, whereby at each operation of said trigger from one to the other of its two positions, a successive one of said locking mechanisms is released and moves from its set position to its released position and a successive one of said components resumes its periodic motion.

15. Apparatus for receiving and storing information represented by a succession of received signals, comprising a plurality of mechanisms each operable to a set position and to a released position, selectively, biasing means urging each of said mechanisms individually to its released position, means for moving said mechanisms to their set positions, repetitively operable triggering means effective at each operation thereof to release a successive one of said mechanisms from its set position, whereupon the so-released mechanism returns promptly to its released position under the influence of said biasing means, means for providing a periodic signal, means for receiving and temporarily holding each of a succession of received signals representative of the information that is to be received and stored, signal comparison means jointly responsive to the signal so held and to said periodic signal for operating said triggering means once following the receipt of each received signal at different epochs of said periodic signal, selectively, under the control of such received signal, and a plurality of information-storage devices, each responsive to the release of a respective one of said mechanisms and to the time relation of such release to said periodic signal for providing a stored representation of the information represented by a respective one of the received signals.

16. Apparatus as defined in claim 15, wherein said triggering means comprises a rotative shaft, means for applying a continual torque to said shaft for rotating the shaft, a detent effective to block the rotation of said shaft and operable to permit a limited angular rotation of said shaft at each operation of the detent, means for releasing a successive one of said mechanisms from its set position responsive to each such limited angular rotation of said shaft, electromagnetic means for operating said detent responsive to electric impulses, such impulses being supplied to said electromagnetic means by said signal comparison means.

17. Apparatus as defined in claim 1, wherein said signal responsive means comprises means for stopping the periodic motion of said ribbon at a fixed epoch in its cycle while continuing the periodic motion of said member, an optical commuter having thereon two side-byside commuting tracks each having alternately arranged light-transmissive and light-obstructing lengthwise sections substantially so disposed that each of said lighttransmissive sections of each track is alongside a lightobstructive section of the other track and vice versa, means for imparting to said commuter a periodic motion synchronized with the periodic motion of said member, said motion of said commuter being in a lengthwise direction of said tracks such that each of said sections in succession of each track passes through a respective one of two side-by-side reference positions, whereby each of said reference positions in alternation is occupied by a light-transmissive section of track while at the same time the other reference position is occupied by a light-obstructive section of track, a source of light disposed for supplying light to said reference positions, such light being transmitted by a light-transmissive section and obstructed by a light-obstructive section, whereby the periodic motion of said commuter periodically commutes the transmission of light from one to the other of said tracks, a light-sensitive transducer disposed to receive light so transmitted, a masking element movable to two difierent positions selectively, said element in each of said positions permitting such transmission of light from said source to said transducer by way of a selected one of said tracks while blocking such transmission by way of the other of said tracks, so that said transducer receives more or less light alternately as the light-transmissive and light-obstructive sections, respectively, of the selected track pass through a reference position, said selected track being either of said two tracks, selectively, depending upon the position of said masking element, electromagnetic means for positioning said masking element in either of its two positions, selectively, responsive to a received signal, and means controlled by said transducer responsive to the amount of light transmitted to it for re-starting the periodic motion of said ribbon at different epochs, selectively, in the periodic motion of said member.

References Cited in the file of this patent UNITED STATES PATENTS 2,456,226 Thorpe Dec. 14, 1948 2,727,222 Bush Dec. 13, 1955 2,774,056 Staiford Dec. 11, 1956 2,783,454 North Feb. 26, 1957

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