DE1918372A1 - Method and device for generating characters on the screen of an electron beam tube - Google Patents

Description

IBM Germany Internationale Büro-Maschinen Gesellschaft mbH

Boeblingen, April 9, 1969
blu-hn

Applicant:

International Business Machines Corporation, Armonk, N.Y. 10 504

Official file number:

New registration

Applicant's file number: Docket KI 9-67-032

Method and device for generating characters on the Cathode ray tube screen

The present invention relates to a method for producing
Characters on the screen of a cathode ray tube by moving the electron beam along a path corresponding to the characters, as well as a device for carrying out this
Procedure.

A number of different methods and devices already exist known, with which one can display letters, numbers and other characters on the screen of cathode ray tubes.

909883 / U82

A first known method uses the entire screen evenly through the beam in horizontal or vertical lines scanned, and the characters are created by selective light and Blanking either as a point probe or as a pattern of horizontal ones or vertical bars. The advantage of this is that there is no beam Always sweeps over the screen at a constant speed, so that with a constant Sig: ial \ vert for the Ilelligiiils control a uniform brightness of the dot or dash pattern results. Of the The disadvantage of this method is that the video arm ation for all characters to be displayed at the same time must be saved, which results in a considerable effort for storage, when good character quality is desired.

Another method is to use an image of what is to be displayed Character is scanned and the signals obtained are used to control the beam in a second tube. On the screen of a so-called Monoscopic tubes are images of the required characters, which are scanned with the electron beam, whereby a secondary electron current is created which is used to control the brightness of the synchronously deflected beam in the actual imaging tube will.

KI 9-67-032 _ 2 -

909883/1482

1318372

Aue »here there is the advantage of the constant stream speed, and characters with any curve shape can be produced will. However, there is the disadvantage of a larger line width, which is used to compensate for screen errors in the Monoscope tube has to accept. In addition, there is a loss of reliability due to the presence of two electron beam tube systems and the need to precisely match the two systems.

In a third method, the characters are made from vectors. composed, that is, of straight lines strung together of different lengths and directions. Every line piece is through two end points are defined, and the electron beam is guided along this line direitit from one point to the next The advantage is that this method can produce very fine lines. There is also no need to scan the entire area covered by the Characters covered; the beam need only travel the required lines, saving time.

However, there is the disadvantage that the speed with which When the electron beam moves from point to point, it is not constant.

KI 9-67-032 - 3 -

909883/1482

BAD ORKSINAL

When a point is reached, the beam stands still while its speed reaches its maximum somewhere on the line. This results in an uneven distribution of the brightness in the characters, which can only be achieved by complex circuits for brightness control can be compensated. A stylization of the signs must also be accepted.

The invention is based on the object of a method for generating characters on the screen of a cathode ray tube indicate, which does not adhere to the above-mentioned disadvantages of the known methods, but which is still a union of them Enables advantages, namely generation of fine line widths, simple memory or generator for generating the character control signals, digital accuracy, uniform brightness or intensity control, generation of almost any curve shape.

This object is achieved according to the invention in that the electron beam deflection control in accordance with the character to be generated in each case control signals for executing elementary steps sequentially are fed at time intervals which are smaller than the time constant of the deflection system, so that the deflection control already receives a new step control signal when the electrical

909883 / U82

KI 9-67-032. 4 _

inner beam designated by the previous control signal Step has not yet reached the end point.

A device according to the invention with a cathode ray tube with a deflection system and deflection control for carrying out the method is advantageously designed so that a time pulse distributor is provided and a pacer that is due to a the signal fed to it »the one character to be generated in each case identified, and on the basis of the time signals supplied to it from the time pulse distributor, step control signals to effect the for the emits relevant characters required beam movements individually one after the other to the deflection control.

An embodiment of the invention is then based on Drawings explained.

In the drawings show:

9 0 9tf8 3/1% .8-2 "

XI 9-67-632 _ 5 - '·

Fig. 1 "the block diagram of an Auslüarungsbeispiels

the invention ;

2 shows a part of a pacer / read-only memory

for a device according to FIG. 1; 3 schematically shows the creation of a character from

Egg treads and the resulting figure

»Of the sign. . -

First of all, it should be noted that in an Elei * ron beam viewing device, in which the individual characters are generated separately one after the other, in principle two deflection devices or controls are required, namely first the coarse deflection that the beam continues step by step from character positions to character positions, and secondly, the fine deflection, which only occurs within the k 'position assigned to a character is effective and the actual

Creates one character each. In the following only the Treated fine deflection, to which the invention relates, while the coarse deflection assumed as generally known and therefore is not described at all.

KI 9-67-032. _ 6 -

908883/148 2

BATH ORIGINAL

A magnetic deflection system is assumed for the embodiment. The principles presented are natural equally applicable to t-sn electrostatic deflection system.

In the circuit shown in Fig. I signals for the to be mapped Signs as digital data from a data source, e.g. a data directory. rbciiungsahlage or an affiliated Memory given to cmca character selection decoder 21. in the Playback device, the signals are stored, e.g. in a circulating memory. In the embodiment of the invention is a Character capacity; t considered from 2 = 64 characters, so in the character code each code word consists of six bits. This capacity: -? ■ but changed in both directions by changing the number of bits will. The character selection coder 21 determines one each of 64 characters and excites the selected line, as later ο -'written more precisely.

First, m-context Zeichcn Erzeugnungs- is * with Fig. 3: -. .hnik beschr: j> en. Each character is a number of elementary '.. ren Segmente- based on the steps referred to, and their ■ umber is determined by dl · shape of the character, wherein the length

Ki 9-67-032 - 7 -

909883/14 82

the individual steps of either the side edge or the diagonal of a Elementary field corresponds. In the exemplary embodiment of the invention described here, there are a maximum of 40 steps - for generation of the most complex considered character required »The For the sake of simplicity, the maximum (to generate 40th steps required) time is assigned to each of the 64 characters, although the device can also be modified for asynchronous operation. Each character is in a matrix of 10x6 elementary fields ™ generated, which is used to achieve a spacing between characters

in a horizontal and vertical direction in a box made of IZ χ 8 Elementary fields. The beam is initially set to an initial position by a coarse deflection system (not shown) is set, which for most characters is position 00 in the lower left part of the relevant character box, and that of the initial position the distraction counter corresponds.

_{When creating a character, you can move up or down (+ Y 1} , -Y) as well as move left or right (-fX, -X) as well as combinations thereof in 45 directions from each grid point controlled in the matrix are provided. This means that the ray from every grid point is the next to one

KI 9-67-032. - 8th -

909883 / U82

BATH ORIGINAL

918372

the eight adjacent grid points' controlled wes the can, "why. · be given information as Ablenkungg für'jedeia step four bits. (One bit for each of the four elementary movements -fX, = X _S 4-Y, -Y).

The mapping of a character is created by saying , aa.es eier Stx * ahl on one? the gev / ÜBsefotsa symbol la approximately-corresponding® path step by step from gifeter point to grid pusikt gtgoteuerfc wis · «! Biad there "unblanked remains soiera not * be executed Swischenbewegimger that nz only% S ^ eupoßitiome ^ mig of SfesaMis d-ieiaesie The. Step-control signals are swa ^ sequeafeieli _c but a © olchen advance gegsfeea _s that jtniß the Steahl on any controlled grid pin sws * Rühe comes "soadera continues to run at the same time, v / eil even before reaching the s" l <a £ si; controlled point the control information s, wm Weitss'iaufen. axd of the next following point given a This sees m && sxii iolgeade way?

The time constant of the fine deflection system used in the exemplary embodiment is 175 nanoseconds _t while the control signals for the one of its steps (vector segment) are generated on average every 125 nanoeconds "which corresponds to a ratio νοη, τΓΙ: 1", thus 2ϊβρ-Γ ? daa deflection during a Zeielieneraeugungssykluo siEeaials a atationäi ^a state s

Kl 9 »67 = 032. - 9 ο

BATH

.Figo3 is the creation of the character B- sur representation of the

In addition to the present invention, when initiating the cycle vA & d, the electron beam is set to Po & Taun 00, WJ® eo at point 32 is due to the first control signal

tsaäehsfe ice diversion from etv / a y2 Emksifej. then se 8t & -ie7? signal _a The third ££ e begins with a distraction from iSeSp dac triQifi; © control signal at tssgeläfeE ¹ 2 ^ / 8 units ^. the fe-äits feegia £? iC fee ?. gss & © s ^: -distraction of about 3 bites is the sixth at about -4 sänaeiten- (thus ara Begias of the fifth "symphony) = s * SßiraU selfesfi iSixift jedoeli aia Hsefei? as a KJäheit behind the

SSeiaeesignsl her _o Since the .Ve ^ tikalbarken im. Character ¹¹ B "si grscc sels sdlij, 1! Control signals are required .. If the B.UC the Schz-il & gn & _B 9 ₀ 10 and 11 sesuitierende.Auslauf nicht- ~ f <s" hind, svt vMrUQ ^ vr & rde the cSteafol on punks 35 next to dsm ge-- ■ wiinschiQ®. Ififeadspi-afcf; 32 get «, urn the expiry of steps 8; Isis .11 3Vl verMadsrijj is given Β, τα point 33 ice negative control signalQ ■ mna the in ver'ak-Blez direction aoch. constant distraction '.

On the globe side, the first control signal for a -

feie ^ kung applied »The ratio of approx. 1 Ti 2 awisciisa cfes. ⁰ Sch ^ iKSseifi des Ablenkun-gs.s-steu.eg ¹ signal and time = - a des Abloaikwngss]? Stems ersnögiicM eiae almost completely new

iöi.ü3 / 1-4i2

right-angled turn. The fact, that the distraction ^ system be brought into a steady state at certain points kasua, also enables a beam guidance with right-angled or sharper kinks - this can approximate a curve as shown in Fig.SB =

The step generator 25 shown in FIG. 1 is, in the exemplary embodiment © lira, a permanent memory consisting of capacitors and diodes, in which the information about the individual steps of each character is stored. Each individual character position is addressed in an optical display device for direct viewing, since each character has to be continuously regenerated in order to preserve the image. With conventional storage methods, the address time for the character position forms an essential part of the total cycle time, the remaining part of which is attributable to the character writing time. If the character writing time z, B "is four microseconds _s as the address period can be two microseconds or more. In the exemplary embodiment of the present invention, the procedure is instead, that the extended code (video information) for an address is called up and dsm! the memory is addressed again for the next cycle. ixL uem. Read-only memory 25 used in the exemplary embodiment is in each case a block of words (a sub-matrix) for the next character

Ki 9-67-032 -11 -

903883 / U82

BAD ORlGANAL

addressed during the time in which the beam is through the coarse deflection is reset to the home position of the next character. Each addressed word block (sub-matrix) contains the Data for all steps associated with the character in question.

As I said earlier, for each character is a significant number • of steps required for which the control signals at intervals of 125 nanoseconds. The time constant of the fine

"The deflection system is 175 nanoseconds. That's why it can

Distraction system between the control signals for the individual steps do not reach a steady state. As a result moved the beam changes continuously after the initiation of a character cycle, and through this simulation one achieves the advantages of the uniform intensity of a device that operates with a constant jet speed works, combined with the digital accuracy of a read-only memory, with disadvantages and drift errors

"not applicable.

As described in more detail below, there is the only one in the exemplary embodiment memory used from a capacitor-diode circuit (Fig. 2). The capacitors form a capacitor matrix, by etching a base plate coated with copper on both sides

KI 9-67-032 - 12 -

909 883 / U 8.2

is made from polyester. A group of lines, the so-called time signal lines, run on one side of the plate and a second group of lines, the so-called interrogation lines, run at right angles to it on the opposite side of the plate. At each intersection of a .Zeitsignal "line to a sense line is to be by the presence or absence of capacitor plates on both sides of the plate bit information (" 0 "or ¹¹ I") present. The intersections provided with capacitor plates are arbitrary as binary, e ones and the intersection points without capacitor coating © as binary zero.

In the production of the sign must be determined at each grid point, if the electron beam upward, to deflect down, left or right, and whether the beam be scanned light or dark must * Thus, for each of the 4 $ possible steps of a Zeichene 5 information bits necessary. The bits of information coming from the permanent memory 25 on lines 81 to 85 correspond to the deflection directions + X ^ -, X ₁ * Y, «Y and the intensity (Z).

The mode of operation of the one used in the exemplary embodiment memory is briefly described in connection with Fig. 2 #

KI 9-67-032 "11-

9O9803 / U02

BATH ORIGINAL

. FIG. 2 shows the partial arrangement for a specific character, the five output lines + X, -X, + Y, -Y and Z. As long as the character is not selected, a positive reference signal is sent to the input terminals 41 and thus to the resistors 43 to 47, which are assigned to the five outputs + X, -X, + Y, -Y and Z respectively . ... . >"■..; ·...

That which is applied to the character selection connection 41 during normal operation Potential is approximately +3 volts. The potential of the time pulse inputs designated TP1 to TP40 is at approximately the same level. kept so that when idle the voltage across the capacitors is usually 0; If by the character selection decoder the character in question is selected, that is at the character selection terminal 41 resulting potential "about G volts.

A diode 51, 52 "» 53, 54, connected and a reference potential via the 7.5 KOhm resistor

'49. placed on these diodes for biasing. When a character is selected becomes, the character selection terminal 41 lying next to it falls • Potential before the generation of the character for about two microseconds about Q volts off, and all capacitors, of the associated Characters are charged accordingly. Since a time pulse of

KI 9t67-032 - 14 -

90 9 8 ^ 3/14 82

BATH ORIGINAL

ι \ JI U SJ / <_

about -3 volts and 70 to 1 00 nanoseconds duration in turn is applied to each dor time pulse connection TPl etc., arises wherever there is a capacitor, a control signal that is sent via the connected output diodes 51 to 55 to the associated Query Verctärkcr (not shown) is routed. Each of the five sense amplifiers is connected to 64 output lines of the read-only memory, each of which corresponds to one of the 64 characters. On the intensity control line 67, signals are in the manner creates that the beam is only scanned lightly during the character generation sequence.

The deflection device described works in push-pull so that a positive signal each for the horizontal and vertical deflection is given in one of the two possible directions.

A pulse given to the connection TPl (see Fig. 2) leads to Provide an output signal from the capacitors 69, 71 and 73 on lines iX, -5-Y, and Z, respectively. In a similar way, each generates subsequent time pulse sends an output signal to the associated Output lines -56 to 59 and 67, which in turn go through the connected diodes 51 to 55 generate a corresponding signal on lines 81 to 85, which in turn is generated by the connected Interrogation amplifier is sensed.

KI 9-67-03 ?. - 15 -

909883/1482

^ÖAD original

The pattern shown in FIG. 2 is chosen arbitrarily and does not apply for any specific character, but is for illustration only the general basics.

From Fig. 3a it can be seen that when the character B is generated, a sequence of 11 deflection control signals for generating the long Vertical line is applied, after which in the uppermost part, as already said *, a control signal for negative vertical deflection is applied

in order to counteract the jet movement that would otherwise go beyond the intended end point. The same technique is used for both coordinate directions. During the generation of the long vertical line, the horizontal condition remains the same, so that none of the time pulse lines belonging to this time interval is connected to the horizontal control signal lines by capacitors. Output signals on lines 81 through 85 are applied to an interrogation amplifier and control circuit shown as block 87 in FIG. This query amplifier and control ^{circuit J} includes query amplifier and control circuits for the X counter 91 and the Y counter 93 and for the light / dark control 95. Each control signal is output as a parallel 5-bit word, two bits for the X and Y counters 91 and 93 an intensity control bit

KI 9-67-032 - 16 -

909883 / U82

for the light-dark control 95 is intended. A signal on the line 97 the X counter 91 advances by 1, a signal -X on line 99 switches the X ~ counter 91 by one unit return. Similarly, a + Y signal on line 101 increments the Y counter and a -Y signal on the line switches it back one unit. The X and Y counters 91 and 91 are not binary counters, since the operation of binary counters with 8 Megahertz is not suitable for this application. In the present embodiment, the characters are known to be in a box generated from 8 χ 12 elementary fields. Accordingly, the X counter has a capacity of eight units, and the Y counter has a capacity of 12 units. There are several options for the technical design of these meters. A well-suited execution is in U.S. Patent 3,403,286. The output signals of these counters are with resistors 107, 109, 111 and 115 weighted and fed to the emitters of the driver circuits 117, 119, 121 and 123 for the deflection system. Thus the. Driver current with a frequency of 8 megahertz switched up or down in steps and as a stepped signal to the deflection system 125 given. As shown in the drawing, the yoke drivers 117 and 119 drive the X-windings 127 and 129 of the deflection

KI 9-67-032 - 17 -

909883/1402

BATH ORIGINAL

systems 125 in push-pull, while the Y current drivers 121 and drive windings 131 and 133, respectively. The X and Y windings are durch.die connected resistors 137, 139 baw. and 143 attenuated so that the magnetic field is applied at a uniform speed due to the 8 megahertz Changes impulses so that signs of uniform intensity emerge. In the exemplary embodiment, a deflection system is used an inductance of 100 microhenries, while the connected damping resistors are 2 KOhm. Same Technique can with electrostatic deflection by using the time constant R * C instead of the one in the electromagnetic embodiment used time constants! L / R are applied. In. In one embodiment, the individual lines were 0.4 mm long, i.e. they represented approximately one point; the device was running synchronous, i.e. 40 time pulses were set for each character »If necessary, the device can also work asynchronously (variable Number of time inapulses or steps per character), and in the simplest version this only requires an additional sensing line, in order to obtain a control signal indicating the end of the character in each case.

KI '9-67-032

ORIGINAL

In the device described above, the character selection signal for the character selection decoder 21 taken from a circular memory, in which only coded ü-bit signals the stored Characters represented. In such an operation, the requirements on the buffer memory are very low, since the video signals from the fixed memory are available and not stored in a circular memory Need to become. The device described combines the advantages of the scanning method with those of the vector method. Characters of uniform brightness with a fine line width can be generated. Then there is the digital accuracy of the permanent memory and the avoidance of adjustment and drift errors. There is also no need for that which occurs with monoscope devices Loss of reliability as well as the additional maintenance required by balancing two independent analog subsystems.

KI 9-67-032 - 19 -

909883/1482

Claims (1)

PATENT CLAIMS 1. Method for generating characters on the. screen a cathode ray tube by moving the electron beam along a path corresponding to the characters and through corresponding light and dark scanning, characterized in that the electron beam deflection control according to the respective characters to be generated control signals for executing elementary steps are sequentially fed with lateral Distances which are smaller than the time constant of the deflection system, so that the deflection control always prepares a new step control signal is obtained when the electron beam has not yet reached the step end point identified by the previous control signal. 2 "Method according to claim 1, characterized in that the elementary steps consist of two components in the two coordinate directions of a right-angled coordinate system, where the Component in each of the two coordinate directions either one Unit in positive direction, zero or one unit in negative Direction can be. 3, the method according to claim 1 or 2, characterized in that the Maximum time interval between the delivery of the control signal for an elementary step to the deflection control and the start 909883/1482 Kl 9-67-032 - so - BATH ORIGINAL the actual execution of this elementary step by the electron beam is equal to the time interval between two successive step control signals. 4. Method according to claim 1, 2 or 3, characterized in that for the points where the electron beam is to pass through a right or acute angle »initially, an excess step control signal is given» which would lead the beam beyond the point in question , and that when this point is reached, a step control signal is given which counteracts at least the excess step control signal so that the electron beam reaches the point in question at an average speed, but does not run beyond it. 5 »Device for carrying out the method according to claim 1 with a cathode ray tube with deflection system and deflection control, characterized in that a time pulse distributor (27) is provided as well as a step generator (25) which, based on a signal supplied to it, identifies a character to be generated , and emits more expensive step control signals to effect the beam movements required for the character in question, one after the other, to the deflection control (91, 107 » 10% 117, 119; 93 * Hl, Π5, 121, 123) due to the time signals of the time pulse supplied to it . -809883/1482 9-67-032 - 21 ~ 6. Device according to claim 5, characterized in that the The step generator (25) is a read-only memory which outputs the step control signals in the form of binary words. 7. Device according to claim 5 or 6, characterized in that ■ a light-dark control (95) is provided for the cathode ray tube, which is connected to the step generator (25) for the purpose of supplying Control signals is connected. 8. Device according to claim 6, characterized in that the read-only memory is a matrix memory in which the information is obtained through the presence or absence of coupling elements (69 »61, 73) is shown at the crossing points of row lines (56, 57, 58, 59, 67) and column lines (TP1 ... TP40); that the matrix memory is divided into areas, each of which is assigned to one of the characters to be displayed and by a signal on a associated character selection line (41) can be selected; and that the column lines are connected to the outputs of the timing pulse distributor (27) are connected; the whole thing in such a way that mcb. Applying a character selection signal a binary value in the form of parallel bits is output as a step control signal on the basis of a time signal on the row lines « 9. Device according to claim 5, characterized gekennzeictaet that in the-Ab- 909883/1482 - 22 - _BATH read control for two coordinate directions one counter each (91, 93) is provided, the content of which is increased or decreased by one unit or else unchanged due to a step control signal can be left, and that driver circuits (117, 119; 121, 123) are provided in which based on the output signals this counter generates staircase-shaped deflection signals which are fed to the deflection system (127, 129, 137, 139; 131, 133, 141, 143) will. 10 «Device according to claim 5, characterized« in that the time pulse distributor (27) emits the time signals to the step generator (25) at time intervals which are equal to each other and smaller than that Time constant of the deflection system (127, 129, 137, 139; 131, 133, 141, 143) of the cathode ray tube. 909883/1482 KI 9-67-032 - 23 -