US2766444A - Electronic character displaying apparatus - Google Patents

Description

Oct. 9, 1956 E. H. SHEFTELMAN 2,765,444

ELECTRONIC CHARACTER DISPLAYING APPARATUS Filed Sept. 1, 1953 4 Sheets-Sheet 1 INPUT I9 4 I [f 1 l N ,22 m 23 W ,24 I? GATE 0 H +DELAY H- DELAY V+DELAY v- DELAY '9 LINE LINE LINE LINE w FLOPS l9 3 PULSE PULSE PULSE PULSE GATE 2 REFORMER Y REFORMER REFORMER Y REFORMER v 38 HORIZONTAL VERTICAL INTEGRATOR 27 /m1-EGRATR G 7 LAMPER CLAMPER &

l9 l5 l5 INITIATING GATE 9 l0 PULSES zo BLANKING 42 CLAMPER DEVICE l6 GATE 4' (10cm PULSES FIG 1 INVENTOR. EUGENE H. SHEFTELMAN Q 7% MW ATTORNEY i 25 i GATE 3 39k LLIMITEU l m'rarq LLIMITETI LLImTETI Oct. 9, 1956 E. H. SHEFTELMAN 2,766,444

ELECTRONIC CHARACTER DISPLAYING APPARATUS Filed Sept. 1', 195:5 4 Sheets-Sheet 2 INVENTOR. FIG-3 EUGENE H. SHEFTELMAN A TTORNEY Ot. 9, 1956 E. H. SHEFTELMAN 2,765,444

ELECTRONIC CHARACTER DISPLAYING APPARATUS Filed Sept 1, 1955 4 She'ets-Sheet 3 sa A PPLY

FROM DELAY LINE I j| I I I I I I 35 3e 37 I ems BIAS VOLTAGE VOLTAGE FIG. 4

Oct. 9, 1956 E. H. SHEIFTELMAN 2,766,444

ELECTRONIC CHARACTER DISPLAYING APPARATUS Filed Sept. 1, 1953 4 SheetsPSheet 4 FIG. 6

INVENTOR. EUGENE H. SHEFTELMA N United States Patent ELECTRONIC CHARACTER DISPLAYING APPARATUS Eugene H. Sheftelman, Jamaica, N. Y., assignor to the United States of America as represented by the Secretary of the Army Application September 1, 1958, Serial No. 377,989 6 Claims. (Cl. 340-318) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to an electronic apparatus for tracing a desired form or character upon the face of a cathode ray tube by direct control of the electron beam of the tube along the path delineating the character or form.

The invention is particularly useful where it is desired to quickly display a form or character with maximum brilliancy. In the present invention this desirable result is achieved without employing the complexity of circuits necessary to a scanning operation.

The invention may be briefly described as follows:

A controlled series of sloping voltage wave forms are applied to the deflector plates of a cathode ray tube. The sloping voltage wave forms are given appropriate amplitudes and polarity to draw and display a selected character upon the face of the cathode ray tube.

A group of characters, for example, the Arabic numerals from 0 thru 9 may be painted upon the tube face by manipulation of its electron beam. To do this each character is divided into a convenient number of increments and a selected numeral is created by putting together in succession the correct increments in proper sequence to create the desired numeral.

In operation each of the character increments is drawn on the tube face by sloping wave forms of measured duration. To draw a complete character automatic selection of the correct sequence of pulses is made and the resulting pulse train is applied to the deflecting elements of the tube. Proper sequence of the pulses is obtained thru the action of the electronic delaylines which may be of conventional construction with their values designed for the particular function required.

It is a primary object of the invention to provide means for selectively and instantly displaying electronically one or more characters or forms in brightly visible form.

A further object of the invention is to provide means for displaying characters which are indicative of results obtained during the process of solving a problem, for example, in an electronic calculating device.

A further object of the invention is to utilize the brightness of a direct trace of the electron beam upon the face of a cathode ray tube for drawing a selected character. A still further object of the invention is 'to provide automatic electronic means for creating the desired character upon the face of a cathode ray tube without a conventional scanning operation.

Other objects and features of the invention will more fully appear from the following description and will be particularly pointed out in the claims. -To present a better understanding of the invention a particular embodiment thereof will be described and illustrated in the accompanying drawings in which:

Fig. 1 is a schematic drawing illustrating the elements of the apparatus in block diagram.

2,766,444 Patented Oct. 9, 1956 Fig.2 is a diagrammatic illustration of the manner in which a character is drawn upon the cathode ray tube.

Fig; 3 illustrates the form of the numerals 0 to 9 inclu siv together with graphical illustration of the" activating pulse trains and sloping wave forms to draw e'ach numeral.

Fig. 4 is a circuit diagram illustrating the elements for accurately timing and shaping the character drawing pulses.

Fig. 5 is a diagrammatic illustration of the resulting values of the output circuit of Fig. 4 for a selected input pulse train coming from a particular delay line.

Fig. 6 is a circuit diagram of the pulse train forming portion of the apparatus.

The invention has many applications and the number of characters available for display can be extended as desired. In the specific embodiment to be described herein the Arabic numerals 0 thru 9 are to be made available for display.

Among the many uses of the apparatus is the instantaneous display of solutions or partial solutions of problems in computing devices or the invention may be used to display selected characters upon announcement or call boards. In such applications the energizing of a selected circuit or the pressing of a button will automatically display the desired number, form or group of numbers.

The medium chosen for displaying characters is one or more cathode ray tubes 10 capable of tracing characters upon their face 11. The characters are drawn by controlling the electron beam 12 issuing from the gun 13 in a manner to cause the spot 14 where the beam strikes the tube face to follow the path necessary to delineate the desired character such as the numeral 2 shown on the face of the tube 10. The control of the beam 12 may be accomplished in any suitable manner such as by means of the two pairs of electrostatic plates 15 and 16 which are energized in a manner to be described.

Before describing the circuits and circuit elements necessary for accomplishing the desired end it may be desirable to first describe the manner in which the characters are constructed upon the tube face by a succession of deflecting voltage wave forms integrated from a succession of pulses. Each pulse causes the beam 12 to trace upon the tube face a certain portion of each character and by selecting the correct succession of pulses a desired character is painted upon the tube face.

To illustrate the above method more clearly reference may be made to Fig. 3 where the graphic representation is shown of the values and arrangement of the pulses which control the form of each numeral and the integrated pulses which deflect the beam.

Fig. 2 shows the path traced by the beam in construct ing Arabic numeral 2. The beam starts from A and stops at B. In Fig. 3 are shown the two sets of pulse trains Vh' and Vv which control the form of each numeral, 0 thru 9, and also the wave forms Vh and Vv which are produced by integrating Vh' and Vv with respect to time. Vh and Vv are the sloping wave forms which are actually applied to the horizontal and vertical deflecting plates. Taking numeral 2 as a specific example, the beam is constrained to move from A to B as follows: Starting from rest at A, the Vv wave form remains 0 while Vh rises linearly positive. This causes the beam to move horizontally across the top bar of the numeral. After this theVh wave form holds fixed at a positive value while the Vv wave form drops linearly negative. This causes the beam to move vertically downward. Next the Vv wave form holds fixed at a negative value while drops linearly negative, coming to rest at 0. This causes the beam to move horizontally in the reverse direction, forming the middle bar. Next theVh wave form holds fixed at 0 while the Vv wave form drops linearly to its maximum negative excursion, causing the beam to move the Vh wave formvertically downwar'dto the "foot of the numeral. Finally the Vvwave form 'holds fixed 'at its-maximum negative value while the V11 wave form rises linearly once more. This causes the beamto move horizontally to point B.on Fig. '2,'and the 'characterhas been completed. "Whenever the defiecting'wave form slopes,the slopes are always the same exceptforsign, and'therefore, it .shoul'dLbe noted that thespeed of the beam acrossthe'face'of the'tube has been everywhere constant, since'tliis is one of the features of the invention. The speed of thebeam'is proportionalto the square root o'f'thesum of the squaresof the derivatives of Vh and Vv at that instant. .The derivatives of Vh and Vvare'Vh and Vv.

It shouldalso be noted that in the formation of certain characters 'such'asthenumeral 4 a diagonal trace must be "made. "This'is accomplishedby applying simultaneously positive or negative going voltages respectively to the'pairs of deflecting electrodesf'l'ian'd 16. This causes the beam 12 to follow a diagonal vector representing the resultant of the two voltages.

Since'the slopes of the deflecting voltagesareeverywhere the same except for sign, it will be'evidentthat whenboth Vv and'Vhslope at the same time the speed of'thebeam will'be 11414 times the speed when not making adiagonal. The maximum variation in.speed'of the beam when 'makingany character will thereforebe in the ratio1:414:1. It is 'highly desirable to-holdthe variation in beam speed. to as' low a value as possible inorder to keep all "parts of characters uniformly illuminated. 'In scanning operations, the nature of. the operation is such that the character cannot be illuminated as uniformly, as is doneby this invention. The principles of the invention may beapplied to the display of a wide varietyof forms and characters.

'While'the invention is useful in manyapplications .a specific use thereof will be presented herein in. connection withcomputing operations wherein information fed to the'computer may have a plurality of classificationsand it is desired to have visual identification ofits class.

The invention provides an efficient apparatus for instantaneou'sly displaying a number whichidentifies its class and thereby indicates into which oneofagroupof storing facilities the information is to be,placed. .The visual information displayed by theapparatus is..useful in many ways as will be obvious tothose skilled in the art.

In'the specific form of theinventionpresented. herein the input innformation is receivedin a .unit.17 shown..in Fig.1 and containing a pluralityof conventionalv flip-flop circuits the outputs of which areconnectedto albinaryto'-decimal diode matrix selector.18 wherein the information is classified intoa plurality ofcategories which in thepre sent example are tenin number. The original input information in passing thruthe flip-flop circuits. and the matrix selector 18. raises the potential of ne of-the ten lead wires up to ground potentialwhile the-remaining wires are resting at negativepotential. Theiparticular wire which is now at .ground.,potential..determines which one of a group of. numerals from thru 9 is .to be displayed by the apparatus. The Arabic numerals tobe displayed are .chosen as one exampleof a. groupof. characters of any nature or configuration which can be'displayed by the apparatus. ,It will be evidenttothose trained in the. art that .theact of grounding. oneof :the. ten switchingleads to select'theproper, nnmeralxcan be performed by numerous types. of electronic circuits and equipment, depending on the manner. in which, the information as to which numeral is desired-is made-available. For instance, if the information arrived in the form of. a sequence of pulses indicatingthe numeraLin-binary form, the sequence could be storedin anelectronic registeraas it arrived. If the stages of .the register were connected to the switching leads thru a .binary-toy-decimal diode matrix, then when the..incoming pulse.ztrain wassfully stored in 'the.register,. only .one of the switchinglead would be grounded.

Each of the ten wires are connected respectively to ten gating circuits "19. The wire which has ground potential will condition its respective gating circuit to pass a pulse applied to circuit 20. The pulse then travels to a group of electronic delay lines 21, 22, 23 and 24. The pulse which is fed to the said delay lines reaches one or more of the lines-at one or more-selected taps thereon desirably thru an isolating diode. 'Itwillth us be seen that by a proper selection of connections to the various taps on the respective delay lines a predetermined pattern is created as a result of which these delay lines will createa chain of pulses having an arrangement which will produce a successive chain.of events. The successive chain of events applied to the specific example described herein will cause the beam of a cathode ray tube to trace out a desired character. 7

Referring again to the delay lines the line 21 is designed to produce a train of positive pulses which create the" horizontal increments of the numeral, the delay line 22 produces a negative pulse chain for creating horizontal increments of the numeral which have to be drawn in the opposite direction, the delay line 23 is designed to create a train. ofpositive pulses for creating vertical character incrementsand the delay line 24 creates a chain of negative pulses for creating vertical increments which have to be drawn in ,the opposite direction. Thus thru the mediumof the delay lines pulse trains are formed having the proper sequence and; polarity to form various numerals upon the face of the tube 10 an outline of which has been described above.

The pulsesas they issue from the delay lines desirably are reformed'in the square wave reformer circuits 25 to be,,described in detail hereinafter. The pulse trains issuing'from the circuits'25 are then fed to limiter circuits 26 where'they are given uniform amplitude and wherein certain of the pulses are given negative polarity.

.From the limiter. circuits the horizontal pulse trains are fed to a horizontal integrator 27 where the final horizontal defiectingvoltages are createdand'fed to the deflector plates 15 of ithetube10. The vertical pulse trains are fed to a vertical integrator.28 the output of which is fed tothe plates 16 of the tube 10.

To start spot'14from a chosen point. on the tube face 11 each integrator is clamped to.a fixedpotential before the numeralis traced. This function is performed by clampscircuits 29 and30 connectedto integrators 27 and 28. These clamp circuits are energized before and after each tracing operation by a voltage derived from the clamping. gate circuit'31. This function will be amplified hereinafter.

'Referring'toTig. 4. of the drawing a pulse reformer circuit isshown such as that used in the pulse reformers 25 of Fig. 1.

An accurately timed series of clock pulses is-employed as a time trimming means to correct the timing of the raw pulses comingfrom the delay lines. The clock pulses are'fed to the grid of a tube.32 in relatively rapid succession. The tube 32 is biased to cutoff so that it is not conducting betweenclock pulses. but each clock pulse shifts the tube. into its conducting state. The plate output of the tube 32 feeds power to the cathode of a pair of tubes 33 and- 34 the outputs of which become divided into two components'the values of which area function of the respective gridpotentials of the tubes 33 and 34.

When a clock pulse alone is applied to the grid of the tube 32 the tube 33 conducts a relatively heavy current since its grid is normally biased to conduct while the grid of the tube"34 which is connected to the output of its delayline' is at-this time at a low potential such as ground potential. 'Since-thetube 33 is conductingheavily the potential of the output line H plus is-at a low value.

The square-wave forming portion of the-circuit consists of a bi-stable flip-flop circuit=35 containing tubes 36 and-37. The;current-ifiowingiin theplate circuit of tube 33 energizes the tube ,371which inturn causes'this -tnbc to establish a stable condition of the flip-flop. Thus the voltage of the output of the H plus line is held uniformly low or at ground potential and no pulse occurs in the output since at this time it is assumed that no plate is coming from the delay line. 7

As shown in Fig. (c) an accurate succession of clock pulses is being fed into the system which acts as the master timing control. In this connection it should be added that the delay lines are so designed that pulses passing therethru will have the same timingas the clock pulses. It is apparent therefore that when a pulse arrives from the delay line 38 to bias the grid of the tube 34 a clock pulse will also be acting to cause the tube 32 to conduct and consequently the tubes 33 and 34. Thus since the pulse from the delay line has a relatively high voltage, for example plus volts, as against the plus 7 volts applied to the grid of the tube 33, the high bias of the tube 34 will cause it to conduct heavily relative to the tube 33. Thus the voltage on the plate of the tube 33 will be increased sharply and thus the H plus output voltage is raised.

At this same instant current in the plate circuit of tube 34 causes the tube 36 of the flip-flop circuit to establish a stable condition at the higher voltage. Thus a square pulse is created. If upon the next clock pulse a pulse from the delay line is also received the pulse length is increased to the duration of two clock pulses and may be prolonged until the flip-flop is caused to shift its condition to the lower voltage by failure of a delay line pulse to arrive at the same time as a clock pulse. It is obvious that depending upon the order in which delay line pulses are received an accurately timed square wave pulse chain is created.

A graphical representation of the above method of pulse formation is shown in Fig. 5 wherein the H plus chain of pulses is illustrated in connection with the delineation of the number 2. In line (a) an initiating pulse is shown. In line (b) a graph of thepulse chain as received from the delay line is shown. In line (0) clock pulses are illustrated in relation to delay line pulses and in line (d) the final square pulse chain is shown.

Thus far the description of the invention has not been concerned with the accurate placement of the characters upon the center of the tube face 11. Obviously the ability of the device for accomplishing this function as a valuable refinement to the broad concept of the invention. The broad invention, however, is not to be restricted to the use of character positioning means.

Character positioning means will be described and shown in connection with Fig. 6 of the drawings. In this figure also are shown the connections between the outputs of all gating circuits 19 to the various taps upon the four delay lines 21, 22, 23 and 24. Thus Fig. 6 illustrates the circuit contained in the cable 38 shown in Fig. 1. Fig. 6 shows the points of connection between each of the lines 39 and the taps 40 upon the delay lines to which they are connected. The distance between each of the taps 44) represents a unit of time delay.

The manner in which the spot 14 is placed in correct position to draw a centralized character upon the tube face may be accomplished in various Ways. The objective of such a means must be capable of placing the spot a at a suitable starting position for each character. A preferred means for accomplishing this result will now be described.

A fixed period of time is allowed for positioning the spot during which time the tube face must be blanked out. To do this a blanking device 41 is provided and placed in a line connected at one end to the initiating pulse line 20 and extending to the control grid 42 of the tube 10. The potential of the grid 42 is controlled by the blanking device 41 to cut off the electron beam during the time interval between the occurrence of the initiating pulse and the instant of actually starting to draw the character and includes the time consumed for positioning the spot. I

To position the spot it is moved from an arbitrary resting position. Any suitable resting position may be chosen. In the example to be described herein this position is shown at (c) in Fig. 2 of the drawings and is the geometrical center of the rectangle embracing all of the characters. The rectangle is two time units high and one time unit wide.

For characters where the drawing thereof is started in one corner of the reectangle the spot must be moved to, right or left half of a time unit and at the same time upwardly or downwardly a full time unit to the right or left corner.

Other characters require only that the spot be moved horizontally to the right or left for half a time unit or, upwardly or downwardly for a full time unit. By reference to Fig. 6 the connections to form the various types of characters are shown.

In Fig. 6 a special wire 43 is connected to a tap 44 on the 15+ delay line. This tap is designed to cause a delay of half of a unit time period. Another wire 45 is connected to a half unit time delay tap 46 on the H- delay line.

It will be seen by reference to Fig. 6 that as the pulse is routed to one of the ten wires 39, for instance, the wire for drawing the numeral 2, a positive pulse of unit duration is applied directly to the plate 16 of the tube 11 thru the wire 43 and to the H half unit time delay tap 46. The combination of the resulting voltages when applied to the tube move the spot into the upper left corner of therectangle. At thisinstant the blanking device turns on the beam 12 and the various increments of the numeral 2 are assembled on the screen 11 in the manner hereinbefore described in connection with the formation of the numeral 2. It should be pointed out that the pulses composing the pulse trains for drawing the char acters after leaving the delay lines are integrated and applied as sloping voltages to the deflector plates of the cathode ray tube 10.

The clamper gate 31 measures a time interval equal to the maximum time required to form a character. At the end of this time period the clamper acts to terminate the cycle and return the spot to its resting position (0). A connection 47 from the clamper gate to the blanking device 44) provides the means which act at this time to blank out the electron beam thru the medium of the grid 41 at the end of the character drawing cycle. By following the chain of events as shown for each character in Fig. 3 and noting the connections to the taps on the delay lines as shown in Fig. 6 it is possible to follow the formation of each character.

What is claimed is:

1. An electron beam controlling apparatus comprising a cathode ray tube, a plurality of input lines representing a group of characters or forms to be drawn upon the screen of said tube, a pulse forming selective switching means for initiating a pulse in a selected one of said input lines, a plurality of tapped electronic delay lines, a gating circuit interconnecting each input channel to selected taps on said delay lines whereby chains of pulses are created by said input pulse applied to a selected input channel and wherein said pulses have a time sequence and polarity of character forming significance and means to integrate said .chains of pulses from said delay lines to obtain a series of voltages whose value change with time along a sloping curve and means to apply the volt ages to the beam deflecting elements of said tube.

2. An electron beam controlling apparatus having the elements defined in claim 1 together with square wave forming, amplitude limiting and integrating means acting to derive beam deflecting voltages from the said pulse trains.

3. An electron beam controlling apparatus comprising a cathode rayrtube having rectangular coordinate -bearn deflecting means, a plurality of input wires each wire being-adapted when energized to produce a ditferent beam control program atgroup of tapped electronic delay lines connected to -said input wires each :wire being connected to-a-selected group of taps onsaid delay-lines, square wavepulse,iorming-means-connected to the output of each delay line and adapted to -form equal -measured pulses, polarizing means to change the polarity of the outputofanleast-some of said square wave devices thereby assembling chains-ofpulses constituting a character drawing program, separate channels interconnecting said pulse'forming means respectively to the horizontal and vertical beam detfecting means of said cathode ray tube and'integrating meansineach of said channels for deriving beam deflecting --voltages from said pulses which act to draw character incrementsin end to end relation on thetace o'f the'saidcathode raytube.

4. An electron beam controllingapparatus comprising an electronic-selecting device responsive to an input signal-andhaving a-plurality of output lines, aplurality of tapped electronic-delay lines interconnected with each of said output lines, eachoutput line being connected to selected taps on said delay lines thereby to form-predeterminedpulse programs, squarewave pulse shaping and polarizing-means connected to the output of each delay line the outputs of which are fed to two independent channels, electron beam indicating means having rectangular coordinatedefiecting means connected to said channels whereby aninput signal fed by said selector to one of said input lines is transformed into trains of electronic pulses arranged in predetermined time sequence and polarity according to said pulse program, integrating means for said pulsetrains and means to subject said electron beam to an electric 'field varying in intensity according to the program set up by said integratedpulse trains to move said electron beam in response to said program whereby straight'character increments are drawn in end to end relation by said beam to form a character.

5. A character displaying apparatus comprising a cathode.ray tube having rectangular coordinate beam control members, .a plurality of input lines each line representing one of agroup of characters or forms to be displayed each character being composed of a plurality of straight graphic structural increments, a;plurality of tapped electronic 'delay lines, gating circuits interconnectingeach of said input lines with=selected tapson-said delay lines,

the taps selected for interconnection being so chosen that an initiating pulse applied thru one of said lines will develop chains o'f pulses at the outputs of saiddclay lines having-a predetermined timed character forming sequence, square wave pulseshaping means connected to each delay line, at. least two of said.delay lines acting to time pulse trains for creating straight horizontal character increments and at least two delay lines being provided for creating straight vertical'character increments, means to shift the polarity of at least someof the pulses issuing from the delay lines whereby a predetermined program maybe created for drawing a selected character increment in end to end relation by increment, integrating means to derive beam deflecting voltages fromsaid pulses and connections from the outputs of the -delay lines controlling the horizontal increments to the horizontal deflecting plates of said cathoderay tube'andconnections from the delay lines controlling the vertical increments to the vertical deflecting 'plates 'of said tube.

-6. A character "displaying apparatus having the elements-definedin claim =5 together with means for applying-aseries of accurately-timed and spaced timing pulses to-the pulse forming circuits at a frequency the same as and occurring-in 'synehronism-with the rate of display of the increments of the-characters or at some multiple of 30 such frequency.

References Gitedin thefile of this patent UNITED STATES PATENTS 2,552,761 Baker May 15, 1951 2,594,731 :Connolly Apr. 29, 1952 2,605,332 Parsons .a July 29, 1952 OTHER REFERENCES Numeroscope for cathode *ray printing, Electronics, February 1948, pp.-98-102.

An electronic alphabet :generator, Electronic -Engineering, May 1948, pp. 139-143.

Abstract #133,475, Sept. 19, 1950.

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