US 3202980 A
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Description (OCR text may contain errors)
Aug. 24, 1965 Filed Jan. 28, 1963 J. J. STONE ETAL CATHODE RAY TUBE CONTROL MATRIX EMPLOYING MAGNETIC SHIELDS 3 Sheets-Sheet 1 umacoum H I RNG grip COUNT7 VE RT\CAL HORIZONTAL J CO U NT ER $WEEP SWEEP GENERATOR GENERATOR \6/ l I 0 u no I a r a i I CHARACTER Z GENERATOR MATRM 2o B1AS SOURCE 22 4'1F' 1I 1 H 4 ,26 52a 50 52:: 52 52A 3 (O O O O I I 50 50A I 9 9 I M95 AsA D b 1% l 46 l 46A 3 3 (0 o o o '44A gm M21, I I 54 H l l I V 17- |,\\4 I ,ue I,\\8 CHARACTER CHARACTER CHARACTER 5$6NAL swam. sew/m. )28 GEN. GEN. GEN. CATHODE 1 20 22 f \24 R w \s LAY 5 5 5 2 GATE 5 G A116 6 ATES APPARATUS CHARACTER J j SELECTlON SOURCE ,uz ,uo c; N G JOSEPH J g 7 LOCK COUNT-ER ROMA/V A. ADAMS BY 075M 1- 7 k A 7TORNEY Aug. 24, 1965 Filed Jan. 28, 1965 MATR\X CARD DR\VER AMPLIFlERS CLOCK PULSE. GEN.
J. J. STONE ETAL 3,202,980
CATHODE RAY TUBE CONTROL MATRIX EMPLOYING MAGNETIC SHIELDS 3 Sheets-Sheet 2 SENSE AMPUFIERS a2 DELAY LINE 94 OUTPUT PULSE R\NG COUNTER 28-2 CLOCK 96 98 100 PULSE ll H; [L FL DRWER 64A AMP. j 127 4A 72A 5 Hf 94A 94B .940 2312;; /O5 H./ STONE POM/Ml A.ADAM$ HOR\ZONTAL IN EN "SWEEP I 2 3 I 4 5 V was PULBE": BY g 2 z ff' n4 A 77'ORNE Y 24, 1 J. J. STONE ETAL 3,202,980
CATHODE RAY TUBE CONTROL MATRIX EMPLOYING MAGNETIC SHIELDS Filed Jan. 28, 1963 3 Sheets-Sheet 3- A SENSE \NHIEHT AMPLlFlER5 GATES DELAV 52 2 UNE METAL 3o 52 SH\ELD DRIVER AMPLIFIERS Rme COUNTER 1 g. 5
CLOCK 96 PULSES H H H H H SENSE AMP? 76A 2 H 2 J1 vaA H 3 80A aoA 6 4 1+ n n 82A 82A 82A 5 H J H fl H 94A 4 OUTPUT nnfl i PULSES JOSEPH J. STONE g$gg 2 3 I 4 5 @QMA/v A.AOAMs PERiODs INVENTORS v BJMW A 7TORNEY United States Patent CATHODE RAY TUBE CONTROL MATRIX EM- PLOYING MAGNETIC SHIELDS Joseph .1. Stone, Glenview, and Roman A. Adams, Skokie,
111., assignors to A. B. Dick Company, Chicago, 111., a corporation of Illinois Filed Jan. 28, 1963, Ser. No. 254,137
8 Claims. (Cl. 340-324) This invention relates to character generators and more particularly to improvements therein.
Various ditferent constructions have been devised in order to generate signals, which, when displayed on cathode ray tube apparatus, represent a character. Such structures range from a resistor voltage divider with provision for gating voltage amplitudes from the various tapping points on the divider and thereafter displaying these, to employing a monoscope tube having characters or symbols drawn on its target, selectively scanning the desired character or symbol, and thereafter applying the signals derived from the monoscope tube as a result of this scanning, to a subsequent cathode ray tube system for proper display.
While these systems are eifective and adequate for the purpose of providing the proper character signals, they all have a common failing. Once they are constructed they are fixed with respect to the characters or symbols to be represented. They do not provide for changes or for a simple mechanism for making changes in the generated character signals. Also, the equipment involved is rather expensive.
An object of this invention is the provision'of a character signal generating system which enables a change for generating different character signals to be made in a very simple manner.
Yet another object of the present invention is the provision of a system for generating character signals, the cost of which is relatively inexpensive.
Still another object of the present invention is the provision of a novel and unique system for generating character signals.
These and other objects of the present invention are achieved by providing two separate sets of conductors, the conductors of each set extending parallel to one another, the conductors of one set being positioned orthogonally with relation to the position of the conductors of the second set. Where the orthogonally related conductors intersect, they are formed into a half loop, so that if a currentpulse is applied to one of the conductors of one of the sets, there is an air coupling to all of the conductors of the other set at the intersection whereby a voltage may be detected at the output of each one of the conductors in the second set.
In order to use this arrangement for generating character signals, a magnetic shielding material is inserted between the orthogonally positioned sets of conductors, which shielding material substantially prevents air coupling between the orthogonally related conductors at predetermined ones of the intersections. If a means for sequentially exciting the conductors of the first set is provided, and the outputs of the conductors of the second set are amplified and applied to tapping points along a multi-tapped delay line, for any given sequential application of current to the linesof the first set, a sequence of pulses is emitted for each line from the output of the multi-tapped delay line, which when displayed line by line on a cathode ray tube face, represents the character desired.
The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, both as to its orice ganization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:
FIGURE 1 is a block diagram illustratingan arrangernent for displaying a character generated by an embodiment of this invention.
FIGURE 2 is a drawing of printed circuit boards in accordance with thisinvention.
FIGURE 3 is a schematic diagram illustrating an embodiment of this invention.
FIGURE 4 is a waveshape drawing illustrating the waveshape generated by the arrangement shown in FIG. 3.
FIGURE 4A shows the appearance of a dot pattern when no shield material is inserted between printed circuit boards.
FIGURE 5 is a circuit diagram of another embodiment of the invention.
FIGURE v6 is a waveshape diagram illustrating the pulses generated by the arrangements shown in FIG- URE 5.
FIGURE 7 is a block diagram of an arrangement for generating and displaying a multiplicity of characters on a cathode ray device employing embodiments of this invention. i
Reference is now made to FIGURE 1 which shows a block diagram of cathode ray display apparatus using a character'signalgenerator of the type comprising this .invention. The diagram is shown to indicate how a character signal generator which is an embodiment of this invention may be incorporated into cathode ray display apparatus. From this, those skilled in the art will :have no diificulty in both the comprehension and construction of the arrangement.
A ring counter 10 has a count capacity which may be determined by the number of horizontal lines which are employed to represent a character on the cathode ray device. The ring counter output is applied to acharacter generator matrix 12, which supplies in response thereto, pulses which are spaced in a manner to represent a charaacter on the face of the cathoderay tube 14, provided that the vertical and horizontal positioning of the cathode ray beam is proper. To achieve this proper positioning the output of the ring counter is also applied to a vertical sweep generator 16, and a horizontal sweep generator 18. The horizontal sweep generator 18, applies line deflection voltages to the cathode ray tube 14, in response to the ring counter output. Each count output of the ring counter causes the horizontal sweep generator to deflect the cathode ray beam across one line. The vertical sweep generator 16 applies vertical deflection voltages to the cathode ray tube 14. The vertical sweep generator is synchronized to provide a vertical deflection voltage equal to the total vertical deflection of a character in response to a total count of the ring counter.
In operation a bias source 20, applies a potential to an electrode of the cathode ray device 14, for the purpose of biasing oif the cathode ray beam. The ring counter 10 commences counting. Assume that the total count capacity of the ring counter is five, therefore, upon the occur rence of the first output of the ring counter, the horizontal sweep generator commences deflecting the cathode ray beam horizontally. Output signals from the character generator matrix have a suflicient amplitude to overcome the bias of the source 20. Thus, if it were the letter E that were to be displayed on the face of the cathode ray tube 14, the character generator matrix would emit four pulse signals which would be displayed along the 0 horizontal line as four bright spots.
Upon the occurrence of a second count output from the ring counter, the vertical sweep generator provides the ver- 7 .tical displacement of the cathode ray beam While the horizontal sweep generator commences sweeping another line. This time the output of the character generator matrix, in response to this second signal, is a single pulse signal resulting in a single bright spot.
The operation of the system for generating the remainder of the letter E should be apparent from the previous description. While the letter B is shown as covering the entire cathode ray.tube' face, those skilled in the art will readily appreciate the fact that the size of the character being displayed may be easily controlled by the amplitude of the sweep signals being applied to the cathode ray tube. Also, the letter may be positioned any place on the face of the tube which is desired, by the simple 'expedience of adding D.C. voltages to the vertical and horiozntal sweep voltages. Reference is now made to FIGURE 2, which shows number of conductors on the vertically oriented circuit board 22, is determined by the number of lines 'of dots or bright spots to'be displayed on the cathode ray tube face.
' Thus, in the letter E shown in FIGURE 1, there are five lines ofispots, there are five printed circuit conductors respectively 24, 26, 28, 30, and 3 2, on the board 22 and five printed circuit conductors respectively 44,46, 48, 50,
and 52, on the board 42. Each one of the printed circuit conductors effectively constitutes five coils connected in series and a return line. Thus, printed circuit conductor 24, has the five coils 24A, 24B, 24C, 24D, and 24E, connected in series and a return line 24'. Similarly printed circuit conductor 44 comprises five coils 44A through 44E connected in series and a return line 44', Each of the printed circuit conductors 24, through 32 and their return lines end in terminals, as for example 34. .Each of all g the printed circuit conductors 44 through 52 and their return lines end in terminals, as for example 54.
All of the printed circuit conductors are insulated, so that upon the placing of the printed circuit board 42 over j printed circuit board 34, the conductors do not connect with one another. However, such overlay of one printed circuit board upon the other does form a' matrixin which,
for example, the windings 24Athrough 24B are positioned directly opposite windings 44Athrough 52A. Accordingly, should a current pulse be applied to the'conductor 24, each one of the windings 24A through'24E'would operate in the manner of the primary winding of a transformer and each one of the windings 44A through 52A would operate in the manner of the secondary windings of a transformer, j whereby a voltage would be induced from eachone of the respective primary windings 24A through 24E into each one of the secondary windings respectively SZA through To summarize the foregoing,'by placing the printed boards, then only those of the windings on the respective boards between which there is no; shield materiahcan operate as a transformer.
' when displayed, represent a character.
'be designated by a two part reference numeral.
' secondary winding of the transformer lies.
Attention is now called to FIGURE 3, which is a circuit diagram representation of an embodiment of the invention employing the components 22, 42, and 26, as well as others for the purpose of generating signals, which Reference numer als applied to the structures in FIGURE 3 correspond to those of the structures in FIGURE 2. Since the two printed circuit boards are superimposed, as previously stated, transformers are effectively provided at the intersections of the printed circuit'boards which are represented in FIGURE 3 by circles at the intersections of the grid of conductors. The circle actually represents' the appearance of the coils when the boards are superimposed. Each one of the transformers which are formed by the superimposed printed circuit boards, will The first part indicates the vertical conductor which forms the primary winding portion of the transformer and the last part is the unit place number of the decimal number designating the horizontal conductor in which the Thus, at the intersection of conductors 24 and 44, the transformer 24-4gis formed. At the intersection of conductors 28 'and 4 6, the transformer 28-6 is formed. 25
The shield 26, which is placed between the two superimposed printed circuit boards, prevents magnetic coupling from being established between primary and secondary windings of the transformers 24-2, 26-2, 28-2 and 30-2, and 32-2. Also transformers 26-6, 26-8, 26-0, 28-0, 30-0, 30-8, and 30-6. The remaining transformers, which are formed at the intersections of the printed circuit conductors, have their primary and A clock pulse generator 60, applies pulses to drive a 'ring counter 10. Each one of the five outputs of the ring counteris applied to a different amplifier circuit respectively 64,66, 68, 70,- 72. Each one of these amplifier circuits applies a pulse of current to the respective conductors 24, 26, 28, 30, and 32, the other ends of which are grounded. Each one of the conductors 44, 46, 48, and 52 are respectively connected to pulse amplifiers respectively 74, 76, 78, 80, and '82. The ,0utput of each one of these pulse amplifiers is connected to a different tap on a multi-tap delay line 90. The delay line may also be made from a plurality of separate short sections of delay line which are connected in series with the amplifiers 74 through 82, connected to each one of the junctions thereof. The output of the delay line 90 is applied to'a load resistor 92. Output developed across the load resistor 92, is taken from an output terminal 94. The signals existingat the output terminal 94, may be applied to an electrode of a cathode ray tube such as 14, for the purpose of overcoming the bias from a bias source, such as 20, whereby a bright spot will be displayed on the face of the cathode ray tube.
In operation, when it is desired to display the letter E, the clock pulse generator is enabled, whereby ringcounter 10 is successively driven through each one i of its count states; This causes a succession of pulses to y be applied by the amplifiers 64 through 72 to the respective lines 24 through 32. In FIGURE 4, the clock pulses are represented by the waveforms 96. The output of the first amplifier 64,, designated by 64A, in FIGURE 4, is applied to the conductor 24. In response thereto, pulsesare induced'in the secondary windings of trans- Jformers 24-4, 24-6, 24-8, and 24-0.. These are applied by the respective amplifiers 74 through to the delay line 90. The delay line serves the function or presenting these pulses at the output terminals '94, as a pulse interval of the first count, the four pulses in the wave train 04A will be represented as four bright spots in line on the face of the cathode ray tube. 7
Upon the occurrence of the second clock pulse 98, the second amplifier 65, applies a pulse of current to the line 26, whereby only a single output will occur on the line 44, since the remaining transformers have their primaries shielded from the secondaries by the shield 26. This output is amplified by amplifier 74, and applied to the output terminal 94. Since the pulse occurs without delay, and since the vertical sweep generator has initiated a vertical sweep in response to the counter output, this pulse is displayed at the beginning of the horizontal deflection for the second count.
Upon the occurrence of the third clock pulse 100, the third count of the counter drives the amplifier 68, which in turn applies a current pulse to the primaries of the transformers connected to the line 23. Only the secondary windings of transformers 284, 28-6, and 28-3 have voltages induced therein. In response thereto, the waveshape 94C appears at the output terminal 94. This is displayed as the center bar of three dots of the letter E.
From the foregoing description it should be apparent how the remainder of the letter E signals are generated as the counter progresses through its count cycle. It should also be apparent that all that is necessary to generate pulse wave trains for representing different characters or symbols, is to substitute, for the pi-shaped shield 26, another shield which blocks coupling between the transformers not required to provide the requisite waveshape, leaving the other transformers with unimpeded magnetic coupling between primary and secondary windings. The format for making the shield pattern is a very simple one. If there is no shield'present then the character generator will generate a dot pattern which is rectangular and which effectively provides a dot for each transformer present. The desired letter or symbol may be superimposed upon the dot pattern. All of the dots which fall outside of the pattern superimposed on the symbol indicate which transformers should have a shield inserted between their primary and secondary windings. Since there is one to one correspondence between the dots in the dot pattern and the transformers formed by the printed circuit boards, this should not prove at all difiicult.
To further exemplify this, attention is called to FIG- URE 4A, wherein there may be seen a dot pattern which is generated were there no shield present in the circuit arrangement in FIGURE 3. A pattern 102, of the character desired to be displayed, is placed over this dot pattern. The uncovered dots indicate the transformer which should have their primaries shielded from their secondaries. Some of the dots which are uncovered are given the same reference numerals as the transformers from which they are generated, in order to show the one to one correspondence. The derivation of the pi-shaped shield 26, for generating the letter E should be apparent from this. I
FIGURE 5 is a circuit arrangement of an embodiment of the invention which is substantially identical with that shown in FIGURE 3. However, by changing the output circuitry slightly, it is possible to cut the shield for insertion between the two circuit boards directly in the pattern of the character desired to be displayed. In FIGURE 5 similarly functioning structure is given the same reference numerals-as were applied in FIGURE 3. Note here however, that-the shield 104,'has the same configuration as the letter E which is the character desired for display.
The clock pulse generator 60 not only drives the ring counter 10 in the manner previously described, but also applies its output to a pulse amplifier 106, The output of the pulse amplifier is applied to five inhibit gates, respectively 103 through 116. These inhibit gates are well known two input gate circuits which in the presence of an inhibiting input to one input can prevent the signal applied to the other input of the inhibiting gate from being transferred to the inhibit gate output. The inhibit input to each one ofthe inhibit gates 108 through 116, are the respective outputs of the amplifiers 7 4 through 02. The pulse amplifier 106 output is the second or inhibit input to each gate. The outputs of the inhibit gates are connected, in the manner described in connection with FIGURE 3, t0 the respective taps along the multi-tap delay line 90. The output of the delay line is applied to a load resistor 02 from, across which output is taken by means of the output terminal 94.
Upon the occurrence of the first pulse output from the clock pulse generator 60, the ring counter 10 applies its first count output to the amplifier 64. This causes a voltage to be induced in the secondary of the transformer 24-2. This voltage is amplified by the pulse amplifier 82, and is applied to the inhibit gate 116. The clock pulse generator 60, also applies an output to the amplifier 106, the output of which is applied to all of the inhibit gates 108 through 116. Accordingly, each one of the inhibit gates 108 through 114 will provide an output to the delay line 90, while the effect of the output of amplifier 82 is .to prevent the inhibit gate 116 from providing an output to thedelay line.
As shown in FIGURE 6, the only amplifier which produces an output in response to the first clock pulse 96, is amplifier 82, as represented by the waveshape 82A. The operation of the inhibit gates is such that the waveshape 94A occurs at the output terminal 94. This is identical with the waveshape 94 as is shown in FIGURE 4. Accordingly, upon the occurrence of the first count of the counter fourdots are displayed along the first lines on the face of the cathode ray tube.
In response to the occurrence of the second clock pulse from the generator 60, the counter is advanced to its second count. As shown in FIGURE 6, inhibit pulses respectively 76A through SZA are generated at the outputs of the respective amplifiers 76 through 82, whereby the only pulse that is applied to the delay line is received from the output of the inhibit gate 108, since no voltagepulse is applied to the amplifier 74, and therefore there isno inhibit pulse applied to the gate 108. The pulse 94B is displayed at the beginning of the second horizontal line on the face of the cathode ray tube.
In response to the third clock, pulse, inhibit signals 80A;, and 82A are applied to the inhibit gates from the outputs of the amplifiers 82 and 80. Therefore, a pulse train consisting of three pulses as represented by waveshape 94C, occurs at the output terminal 94. These three pulses are displayed on the third horizontal line on the cathode ray tube face.
It should be apparent from the foregoing description how, by the use of the slightly altered output circuitry, it
is possible to generate signals for representing any character desired when displayed on the face of the cathode ray tube, by cutting out the pattern of the shield 104 in the shape of the character desired to be displayed. All that is required for generating signals to represent another character is to merely separate the two printed circuit boards, remove the shield present therebetwee-n, and insert the new shield having the new pattern in its place. The printed circuit boards may then be pressed together by any suitable clamping means. A plurality of these character signals generators may be employed and selectively connected by means of any suitable known selecting mechanisms to cathode ray display apparatus.
A simple arrangement for such a selective display device is shown in FIGURE 7. A single ring counter 110, driven by a clock pulse source 112, may be employed. The output of the ring counter drives five coincidence gates for each character signal generator employed. Each five gates is designated as a gate set. Thus, in FIGURE 7, three gate sets respectively 120,122 and 124 are shown receiving one output from the ring'counter 110 and a second selecting output from a character selection source 126 Each one of the character signal generators hasits output connected to the cathode ray display apparatus 128. The synchronizing signals from the ring counter 110 are also applied to the cathode ray display apparatus 128; The character selection source 126 enables one of the sets of gates 120 through 124.v The ring counter 110 in response to the clock signals applies its output successive ly to each one of the five gates in the selected set. The character signal generator associated with the selected set will have the circuitry shown in" either FIGURE 3 or FIGURE 5, commencing with the drive amplifiers 64 through 72, which receive the outputs of the selected gate set. The output of the delay line of each character. signal generatoris connected to the cathode ray display apparatus 128. The arrangement shown maybe employed for generating words, or sentences, orany other display.
There has accordingly been shown and described herein a novel, useful and simple arrangement for generating signals in a pattern whereby upon display by-cathode ray tube apparatus the signals represent a character.
We claim: 1. A character signal generator comprising a plurality of transformers each of which has a primary winding and .series, means for magnetically shielding the secondary windings of predetermined ones of said transformers from the primary windings of said predetermined ones of said transformers for preventing a voltage from being induced in said secondary windings in response totcurrent in'said.
primary winding, means for sequentiallyv applying a current pulse to each one of the columns of a series connected primary winding, delay means to which each one of said rows of series connected secondary windings are connected for sequentially arranging output f'rom the secondary windings of transformers which are disposed in a single column of transformers, and'means for displaying in successive lines after eachenergization of a different column of series connected primary windings .the output of said delay means. g Y
2. A character signal generator comprising'a plurality of transformers,each said transformer having a primary and secondary winding, said transformers being arranged in columns and rows, means connecting all the primary windings of transformers in each column in series, means connecting all the secondary windings of the transformers in each row in series, means for magnetically shieldingthe secondary windings of predetermined onesof said transformers from their primary windings, means for apply- 7 ing a current pulse in sequence to each one of the columns of series connected primary windings, whereby a voltage is induced in the secondary windings of those'transformapplying current pulses to said columns of primary windings and to the outputs of said secondary windings for displaying a predetermined character as determinedfby 3. A character signal generator comprisinga plurality of transformers arranged in columns and rows, each of said transformers having a primarywinding and a secondcitingin sequence with ajc'u'rrent pulse each one of said columns of said series connected primary windings, a delay line having taps spaced therealong, means connecting each of said rows of series connected secondary windings to a different tap along said delay line, display means connected to the output of said delay line, and means for applying to said display means synchronizing signals from said means for sequentially exiting said columns of series connected primary windings for displaying the signals received by said display means from said one end 'of said delay line.
4. 'A character signal generator as recited in claim 3, wherein the primary windings of said plurality of transformers comprise printed circuit wiring deposited on a first board, the secondary windings of said plurality of transformers comprise printed circuit wiring deposited upon a second board, said second board being superimposed upon said first board to provide magnetic coupling between the primary and secondary winding, and said shield means for preventing magnetic coupling between the primary windings and secondary windings of predetermined ones of said transformers comprises a magnetic shield which is inserted between said first and second boards.
5. A character signal generator comprising a plurality -of transformers arranged in columns and rows, each of said transformers having a primary and secondary winding, means connecting in series the primary windings of each column of transformers, means connecting in series the secondary windings of each row of transformers, shield means for preventing magnetic coupling between predetermined ones of said primary and secondary windings in QCCOIdHllCfliWlih the shape of a predetermined character desired to be displayed, a counter having each ings of each row of transformers to a different one of said delay line tapping points, means for energizing said counterto sequentially advance its count to sequentially excite the series connected primary windings of each column of transformers, and means to which said delay line output is applied for displaying in successive lines after each output of said counter the signals received from the series connected secondary windings, of said rows .of transformers. I a
'6. A character signal generator comprising a plurality of transformers disposed in rows and columns, each said transformer having a primary'and secondary winding, means connecting the primary windings of each column of transformers in series, means connecting the secondary windings of each row of transformers in series, shield means for preventing magnetic coupling between predetermined ones of said primary and secondary winding in accordance with the shape of a predetermined character desired to be displayed, a ring counter, means for ad- ;vancing said ring counter through its successive count states, means for connecting each count state output to the series connected primary windingsrof a different column of transformers, an inhibit gate for each row of secondary windings of each row of transformers to the the location of the ones of said transformers having their. secondary windings shielded from their primary windings."
ary winding, means connecting -in series the primary windings of each column of transformers, means' conpredeterminedones of said transformers inaccordance.]'
with a character desired to be displayed, means for exor inhibit gate for that row to inhibit said gate in the presence 1 of an output from the secondaryiwinding in the associated row of transformers, means for applying a pulse signal to every one of said inhibit gates each time said counter advances its count state whereby said inhibit gates will provide output signals when there is no inhibit signal "received from the secondary windings in the row of transformers with which it is'associated, means to which the signals from said inhibit gates are applied for spacing said signals by predetermined amounts, and means for displaying in successive lines after eachicountstate output,
the output of said means for spacing signals alongra different line to produce said predetermined character.
7. In a character display system of the type wherein characters are formed on a display device as a plurality of successive adjacent lines along each of which are spots displaced from one another, apparatus for providing signals from which said spots are derived comprising a plurality of transformers having primary windings in the form of printed circuit conductors on one board and secondary windings in the form of printed circuit conductors on a second board, said first and second boards being superimposed on one another, and a magnetic shield positioned between the first and second boards for preventing magnetic coupling between the primary and secondary windings of predetermined ones of said transformers in accordance with the signals desired for forming a predetermined character.
8. In a character display system of the type wherein characters are formed on a display device has a plurality of successive adjacent lines along each of which are spots displaced from one another, apparatus for providing signals from which said spots are derived comprising a plurality of transformers disposed in rows and columns, each transformer having a primary winding and a secondary winding, the primary windings of each separate column of transformers being connected in series, the secondary windings of each separate row of transformers being connected in series, said separate series connected columns of primary windings comprising printed circuit conductors on a first substrate, said separate rows of series connected secondary windings comprising printed circuit conductors on a second substrate, said second substarte being superimposed on said first substrate, a magnetic shield inserted between said first and second substrate, said magnetic shield being shaped for preventing magnetic coupling between predetermined ones of said transformer primary and secondary windings in accordance with a character desired to be displayed, means for successively applying current pulses to each separate column of series connected primary windings, means for spacing the signals induced in said rows of series connected secondary windings in response to the succesive excitation of said columns of primary windings, and means for displaying in successive lines the output of said means for spacing to produce said predetermined character.
References Cited by the Examiner UNITED STATES PATENTS 2,814,031 11/57 Davis 340174 2,856,597 10/58 De Mo tte 3-40-l66 6,012,240 t1-2/6l Klahn 340-l66 3,027,548 3/62 Vaughn 340174 3,103,658 9/63 Chiang 340324.1
NEIL C. READ, Primary Examiner.