US2834911A - Multi-beam convergence circuits - Google Patents

Description

ay 13, 1958 M. D. NELSON MULTI-BEAM coNvERGENcE CIRCUITS 2 Sheets-Sheet l Filed Oct. 5, 1955 E m Vl M x w w j Z F. i Wr, n www mm f f www www ma, 5 7l MMM :VWO www 2 Z k MP wm 0D. 0 wm M W N O S L E N D. M.

MULTI-BEAM CONVERGENCE CIRCUITS 2 Sheets-Sheet 2 Filed OO'C. 3, 1955 IN VEN TOR. v n f s F www ZI,834,91 l Patented May 13, 1958 tice MULTI-BEAM coNvnnGnNcE cincuirs Morris D. Nelson, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application October 3, 1955, Serial No. 539,883

9 Claims. (Cl. 315-13) The invention relates to systems for controlling the deection of electron beams of cathode ray tubes, and it particularly pertains to such systems in which a plurality of electron beams are deected by common deflection circuitry.

One type of cathode ray tube, or kinescope with which the invention may be successfully used is a color kinescope of the general type described in an article A Three-Gun Shadow-Mask Color Kinescope, by H. B. Law published in the Proceedings of the IRE, volume 39, No. l0, for October 1951 at page 1186. Part of the target electrode structure of such a tube is a luminescent screen in which different phosphor areas produce differently colored light when excited by electron beams impinging from different angles, the angle of impingement determining the particular color of the light produced. For satisfactory operation of such kinescopes, it is necessary to effect substantial convergence of the different electron beams at all points on the raster formed by deflecting the three electron beams in two mutually perpendicular directions. A general discussion of this beam convergence problem will be found in an article entitled Deection and Convergence in Color Kinescopes, by A. W. Friend, published in the Proceedings of the IRE, volume 39, No. l0, for October 1951 at page 1249. One type of multi-beam kinescope to which the invention particularly pertains includes a pair of magnetic pole pieces for each beam located internally of the kinescope envelope. These internally located pole pieces are energized by magnetic components arranged outside the kinescope envelope. These magnetic components may be entirely electromagnetic or they may include some permanent magnetic structure since the internally located pole pieces usually require static as well as dynamic energization. In general, it is desirable to provide such convergence means for kinescopes with the minimum of additional components.

An object of the invention is to provide improved circuitry for effecting convergence of the plurality of electron beams of a multi-beam kinescope.

Another object of the invention is `to provide an improved circuitry for effecting convergence of the plurality of beams of a multi-beam kinescope with passive network elements.

According to the invention parabolic convergence current waves for application to the pole-piece exciting windingsV of .a multi-beam kinescope are obtained by integration of pulse and sawtooth voltage waves in resistive and inductive reactance circuits. The circuit features ,adjustable resistance elements connected in the cathode lead `of a vertical deflection wave amplifying tube which in conjunction with an inductance element provides variable amplitude parabolic voltage waves at the vertical deflection rate which are integrated upon application to the highly inductive convergence system windings to cause currents of parabolic Waveform to flow therethrough. Other resistive elements connected ,across a center-tapped isolated winding on a vertical deection wave transformer provide variable amplitude positive or negative sawtooth voltage waves at the vertical deflection rate for tilting the parabolic waves. A voltage pulse obtained from a horizontal deflection wave amplifying circuit is applied to a plurality of series circuits each comprising an adjustable inductance element and a resistance element of low impedance with respect to that of the inductance element. The amplitude of the sawtooth voltages thus produced at the horizontal line deflection rate may be adjusted by varying the inductances in the circuits to provide variable amplitude current waves at horizontal deiiection rate of parabolic waveform upon application sawtooth voltages to the highly inductive convergence system windings. A compensating capacitance element may be interposed in series with each resistance element to provide more suitable waveform and also in order to reduce the power loss by permitting the use of larger values of resistance elements. The resulting parabolic current waveform is corrected for tilt by adding a sawtooth current wave of horizontal deflection rate to the parabolic wave. Another capacitive reactance element is connected between the junction of the compensating capacitance element and the resistance element and the point at which the horizontal voltage pulse is applied to the inductance element. The two capacitive elements form a capacitive voltage divider. The other capacitance element may be adjustable in order to vary the amplitude of the sawtooth component which is added for tilting the parabolic wave. By means of a trilar winding, interposed in the circuit to prevent the horizontal deflection rate currents from llowing in the vertical deection Wave circuits whose impedance is normally of a low value at which the horizontal frequency components would be excessively loaded, both horizontal and vertical convergence current waves ow in the same windings, The use of a tritilar winding effectively isolates the separate convergence circuits and also insures that the horizontal rate voltage pulses are initially of the same value in each of the convergence circuits despite variations in the applied voltage due to power line :uctuations and the like. Alternatively, an arrangement is suggested in which a triilar winding on the horizontal deflection wave output transformer is used to produce the desired pulse voltages and at the same time provides choke action to keep the horizontal convergence waves out of the source of vertical convergence waves.

ln order that the practical aspects of the invention may be fully appreciated, an express embodiment, given by way of example only, is described hereinafter with reference to the accompanying drawing in which:

Fig. 1 is a functional diagram of a television receiving apparatus in which the invention may be incorporated;

Fig. 2 is a cross section view of a multibeam kinescope of the type to which the use of the invention is particularly applicable; and

Fig. 3 is a schematic diagram of an embodiment of the invention.

Referring iirst to Fig. l, there is shown a functional diagram of portions of a color television receiver to which the invention is particularly adaptable, and which receiver may otherwise comprise entirely conventional circuitry. In such a receiver, color television signals ap pearing at an antenna are applied to a radio frequency wave amplifying circuit and the output therefrom is applied along with the Wave obtained from a local beat oscillation generating circuit to a frequency changing circuit. The output of the frequency changing circuit is applied to an intermediate frequency (L-F.) amplifier which may be one having separate channels for picture and sound signals or one in which both picture and sound signals are amplified at the same time. A video demodulating circuit 17 is connected at terminal 16 to the I.F. amplifying circuit for deriving a video wave from the television signals. The detected video signals are amplified in a video frequency (V.-F.) amplifying circuit 18. Sound signals are derived from the sound I.-F. amplifying circuit, or from the demodulating circuit 17 or from the V.F. circuit 18, for further processing in a sound L-F. amplifying circuit, an aural signal discriminating circuit, an audio frequency (A.-F.) amplifying circuit and a transducer, usually in the form of a loud speaker. applied to a circuit 19 for converting luminance and chrominance components into proper form for application to the signal input circuitry of an image reproducing display device, or kinescope 20. The output of the video frequency amplifying circuit is also applied to synchronizing pulse separating circuit 24 to separate the syn- .chronizing pulses from the picture signals and to separate the horizontal synchronizing pulses from the vertical. The separated vertical synchronizing pulses are applied to a vertical deflection wave generating circuit 2S and thence to a vertical deflection wave amplifying circuit 26, while the horizontal synchronizing pulses are applied to a horizontal deflection frequency oscillator and frequency control circuit 27 and thence to a horizontal deflection wave amplifying circuit 28. The high voltage and focus voltage generating circuit may be coupled to the horizontal deflection wave amplifying circuit. The vertical deflection wave amplifying circuit 26, the horizontal deflection wave amplifying circuit 28 and the high voltage and focus voltage generating circuit 29 are coupled to the kinescope 20 to supply vertical and horizontal deflection waves and focus and ultor potentials. The vertical deflection wave amplifying current 26 and the horizontal deflection Wave amplifying circuit 28 are connected to a convergence wave generating circuit 30 according to the invention for generating convergence waves for dynamic convergence of individual beams of the multi-gun kinescope 20. A low voltage power supply, normally connected to the local A.-C. power lines, is arranged to 1 furnish direct energizing potentials to all circuits. An automatic gain control amplifying distributing network is coupled to the synchronizing pulse separating circuit 24 or the video frequency demodulating circuit 17 or to the video amplifying circuit 18 to supply control potentials to the desired ones of the circuits previously mentioned. Normally the R.-F. and I.-F. amplifying circuits are at least so supplied.

The kinescope 20 may be of the same general type as that disclosed in the H. B. Law paper hereinbefore mentioned. The kinescope 20 preferably has a luminescent screen provided with a multiplicity of small phosphor' areas arranged in groups and capable of producing light ofthe different component colors when excited by electrons. In back of and spaced from the screen there is an apertured masking electrode having an aperture for and in substantial alignment with each group of phosphor areas. The luminescent screen and the masking electrode may have planar or partially spherical surfaces; the invention being equally applicable to either form of target electrode structure.

The kinescope 20 also has a plurality of electron beams equal in number to the number of component colors in which the image is to be reproduced. Conventionally, three such electron guns, which may be entirely conventional in structure consisting of a cathode, a control electrode and a focusing electrode, are arranged substantially parallel `to\y produce three separate electron beams by which to energize respectively blue, red and green phosphor areas of the screen of the kinescope.V The kinescope 20 also contains a beam accelerating electrode, or ultor, consisting of a conductive wall coating on the inner surface of the envelope of the kinescope and extending out to the region of the target electrode structure. When these electron beams are properly converged at the target The output of the V.F. amplifying circuit isv structure, the electrons pass through the apertures of the maskingelectr'ode from different directions and impinge on different phosphor areas of each of the groups so as to produce light in the three component colors. The electrodes of the kinescope 20 may be energized in the conventional manner and the color information signals are applied so that the electron beams are modulated in intensity in accordance with the information carried by the color-representative video signals derived from the translator circuit 19. The video signal source will not be described further herein since it does not form an essential part of the invention.

Associated with the color kinescope 20 is a deflection system yoke, which may be entirely conventional and in which may be mounted two pairs of suitably placed windings electrically connected so that when properly energized, electromagnetic fields are produced to effect angular deflections of the electron beams in both the horizontal and vertical directions to scan the usual rectangular raster at the target electrode structure. Deflection waves for application to the deflection system windings are obtained from the vertical and horizontal deflection wave amplifying circuits 26 and 28 respectively.

The beam convergence system in accordance with the invention also includes a plurality of electromagnetic field producing elements arranged about the neck of the kinescope adjacent to the predeflection paths of the electron beams. An example of such construction is shown in Fig. 2 wherein three magnet assemblies 31, 32 and 33 arranged about the neck of a kinescope envelope 35. The precise location of the magnet assemblies is not necessarily indicated in Fig. 2 but it is to be understood that each of the magnet assemblies is located relative to the path of one of the electron beams to influence that one beam to the virtual exclusion of the others. The magnetic fields produced by these magnet assemblies are transverse to the associated beam paths and in a direction to move the associated beams radiallyl relative to the longitudinal axis of the kinescope. The convergence magnet assemblies 31-33 are usually energized by a subtantially unidirectional current component to effect an initial convergence of the electron beams substantially at the target electrode structure. Normally, convergence is initially made at the center of the screen, however, this initial convergence may be made at any point, for example, at Vonecorner of the raster. In order to do this, the unidirectional energizing current component is effected in such a way that the magnet may be individually energized in different magnitudes.

The convergence magnet assemblies 31-33 are also dynamically energized by wave energy derived from suitable generating means so as to effect a variation in the magnitude of the transverse elds produced and to vary the deflection of the individual electron beams as a function of the overall deflection of the three beams. In this way suitalble variations are made in the convergence angles between the various beam components in theindividual beams so as to produce the desired convergence of the beams substantially at all points of the target electrode structure. All of the magnet assemblies being the same, only one will be described in detail. The magnet assembly 31 comprises a core, which may be in one piece, but is shown in two pieces 36, 37 having legs 38, 39 extending at right angles to the main body of the core. If direct current is utilized to afford static convergence, the core might conveniently be in one piece. As shown, however, the core of the magnet assembly 31 is split into two pieces 36, 37 and mounted between the core pieces in suitable recesses formed therein is a swbtantially cylndrical permanent magnet 40. This magnet is polarized substantially diametrically so as to present north and south poles in the two halves thereof substantially as indicated. The permanent magnet 40 may be provided with suitable adjusting facilities, such as a screw driver slot, formed in one or both ends. The rotation of the permanent magnet 40 between the core sections 36, 37 enables the strength of the permanent magnetic eld produced to vbe adjusted in both magnetic and polarity. Windings 41, 42 are mounted on the legs of the core pieces, although alternatively the windings may be wound as a unitary structure and mounted on the main body portion of the core. A set of pole pieces 43, 44 is provided internally of the kinescope envelope 35 for each of the convergence magnet assemblies. The internal 'pole pieces 43, 44 are arranged to increase the eiectiveness of the associated magnet assemblies by decreasing the reluctance of the magnetic circuit and considerably improving the ux distribution of the eld produced between the pole pieces. The convergence magnet assemblies 31-33 produce fields which in the vicinity of the electron beams associated therewith are substantially transverse to the axis of the kinescope. The electron beam associated with each of the magnet assemblies may be readily moved toward or away from the longitudinal axis by adjusting the amount of magnetic ux in the respective assemblies 31-33. The direction and magnitude of such beam movement is controlled by the energization of the windings 41, 42 and rotation of the permanent magnet 40.

The convergence magnet assemblies 31-33 may be energized by means of the circuit arrangement shown in Fig. 3. The convergence magnet assemblies may be substantially identical, and may be energized by substantially identical circuits. Therefore, the description will be limited to the particular circuits by which the windings 41 and 42 of the convergence magnet assembly 31 are energized, it being understood that the same description applies equally as well to the circuits illustrated for energizing the other convergence magnet windings except Where specically noted.

Referring to Fig. 3, synchronizing pulses of vertical deflection rate are applied at input terminals 51, 52 to a vertical deection wave oscillator tube 54 for producing a sawtooth voltage Wave `across a charging capacitor 56 connected in series with a peaking lresistor 57. The peaked sawtooth voltage wave is applied by way of connections including a coupling capacitor 58 to a vertical deection wave amplifying tube l59. Vertical sawtooth current waves are induced in a vertical deection wave output transformer 60 by a primary winding 62 connected in the -anode circuit of the vertical amplier tube 59. The sawtooth deflection wave appearing across a `secondary winding 64 is applied to a vertical deflection system winding comprising sections 66, 6.7. No Y provisions are shown in the circuit for deection centering of the scanning beams, but conventional centering current circuitry may be employed in known manner. A sawtooth voltage wave at horizontal deection rate is applied at input terminals 71, 72 of the horizontal amplifying tube 74. A sawtooth current wave isl induced by the connections to the amplifying tube 74 in a winding 76 of the horizontal deliection wave output transformer 73. The deection pulse voltage and sawtooth current wave appearing inthe output portion of the winding 76 is applied to a horizontal deection system winding comprising two sections 81, v82 the latter of which is shunted by an antiringing capacitor 83. Again no centering provisions have beenV shown, but these may be readily supplied according to the known art.

A sawtooth voltage wave at the vertical deflection rate appears across an unbypassed resistance element 86 in the cathode lead of the vertical deection wave amplifying tube 59. This resistance element 86 is'used to return the cathode to the point of reference potential, .shown as4 ground, and to provide a sawtooth voltage wave for producing the vertical convergence parabolic current wave. An inductance element 88 is connected ybetween the unbypassed resistance element 86 and a plurality vof variably tapped Vresistance elements or potentiometers gli, there being one such resistanceelement for each circuit desired.

In the example shown, there is a potentiometer 91k for `the red controlling electron beam, another potentiometer 91G` 'forthe green controllinng electronubeam, vanda further potentiometer 91B for the blue controlling kelectron beam. Hereinafter, the suffixes R, G and B are dropped from the reference numerals when considering' the general aspects of the component circuits, and it should be understood that the description with reference by means of a general reference number applies equally well to the 'specific component circuits. Due to partial integration brought about by the *inductance element 88, the potential across the parabolic convergence voltage level setting potentiometers 91 very closely approximates a parabola. at thel vertical deection rate. Movement of the varms 92 of the potentiometers 91 serves to adjust the amplitude of the parabolic voltage components available for converging the individual electron beams in the vertical direction.

By use of the inductor 88 for partiallyvintegrating the vertical sawtooth wave, the expense of a large electrolytic capacitor previously used for lthis purpose is eliminated. More important is that the initial operation and the sta- -bility of the circuit is greatly improved because the manufacturing tolerances of inductors yare closer than that of electr-oly'tic capacitors. The inductance of inductors does not tend to vary with age, as does the capacitance of electrolytic capacitors. Furthermore the integrating inductor 88 has a negligible effect on the output vertical deection wave, which means that a less expensive ver-tical output stage may be used Ato secure the ydesired results.

By means of variably tapped Vresistance elements or potentiometers 94R, `94G and l94B connected in parallel across a center tapped secondary winding 104 of the fvertical vdeflection wave output transformer 60, Apositive or negative sawtooth waveforms lat the vertical deflection rate may be obtainedby movements of the taps or `arms 9S respectively of the resistance elements or potentiometers 94. At an inter-mediate position of each poten- `tiometer arm, the potential .from the larm to the neutral point of reference potential, shown as ground, is zero.

Moving the potentiometer ar-m to either `side of neutral causes either a positive or negative sawtooth wave to appear `bet-Ween the ar-m 'and the point of reference potential i'of amplitude proportional to the degree of movement of the arm. Each ofthe .convergence windings is divided into Atwosections 41, 42 as shown in Fig. 2. Referring again to Fig. '3, the plurality of convergence pole-piece exciting winding sections are individually connectedy ibetween the arms 92 of the parabola amplitude controlli-ng potentiometers- 91 and the arms 95 of the tilt cont-rolling potentiometers 94, bymeans of a triiilar wound inductofr 100 having conductors 101-103, a pluralitynof inductors 104R, 104G and 104B. The inductors 10.0 and 104 are more resistive than `inductive at the vertical frequency as they are intended for operation on the horizontal current components, so that the sawtooth vertical deection frequency voltages are unaffected by the horizontal components but are integrated by the substantially high inductance of the convergence system windings 41, 42 to produce parabolic current flow. The amplitudes of these parabolic components are determined by the positions of the arms 92 on the parabola adjusting potentiometers 91.

A color purity magnet is used with tri-color kinescopes of the type mentioned hereinbefore. This magnet operates by directing 'the three electron `beams across thellongitudinal yaxis of 'the kinescope and this beam movement, together with some component tolerances, makes y'tilting necessary. The parabolic waves are tilted, or shifted ls'o that the minimum amplitude points are either toward :the beginning or the end of the waves, by positioning the yarms on the sawtooth wave amplitude setting potentiometers 94. For this reason these potentiometers 94 are usually termed tilt controls. The approximately parabolic vertical voltages are somewhat still further integr-ated by 4the inductan'ce of `the convergence system 7 `windings'sections and the `inductors104 to yield lthe desired..vertical frequency parabolic current waves.

With tri-colored kinescopes of the type described, the electron guns'are mechanically tilted toward the central `axisof the kinescope so that the individual beams virtuzally Vconverge at the center of the phosphor screen. However, -because of manufacturing tolerances, a static component of magnetic field is necessary to set the beam direction of each gun precisely. This field is obtained by means of the rotatable permanent magnets 40 in the convergence coil assemblies 31 as shown in Fig. 2. The field required is a function of the error and the square root of the ultor potential, the latter of which follows the power yline voltage in shunt tube high voltage regulating systems.

Both the vertical and the horizontal dynamic convergence Yvoltages are applied to the convergence system windings 41, 42 for alternating current flow only. When the components of magnetic eld these voltages produce are added to the static component required for center convergence as previously adjusted, the total field when scauning the center of the raster will be in error by an amount equal to .the instantaneous value ofy the'dynamic convergence voltage. This error is corrected by adding a compensating field of equal value and opposite sign by means of a resistance element 106 which is connected to a source of intermediate potential obtained from the same low voltage rectifier that supplies the circuits developing the dynamic components; that is the horizontal and vertical deflection wave translating stages whose outputs vary directly with the power line voltage. circuit shown in Fig. 3 the compensating field varies in the same manner as the dynamic fields so that for normal power line voltage variations, there is high degree of `tracking over the raster, resulting in excellent beam con- VergenCC.

A voltage pulse wave o f horizontal recurrence rate is applied to a seriescircuit comprising an inductive element and-afresistive elementV of lower impedance than that of the inductive element. Tihelserie-s ycombination is .therefore predominately inductive and thevoltage across the series circuit is therefore approximately4 sawtooth in shape, being an integraloftheapplied pulse voltage. The voltage developed across` the -resistanceelement is similarly `sawtooth in shape". windings in shunt Vwith the resistance element, the sawvolta-ge wave is integrated to produce parabolic current wave through the highely inductive vconvergence systern windings... If the impedance of the convergence system winding is'much larger than'thatof the resistance element, thesawtooth voltage wave shape will be but slightly affected.y By interposing a compensating capacitive element in the series with theresistance element, the resulting sawtooth voltage wave will-be symmetrical and slightly S-shaped. This latter arrangement provides a more perfect parabolic current waveform in the convergence winding and permits the useofY larger values of resistance elements. This results in'ilower power loss which is advantageous since the horizontal deflection frequency power dissipated in the convergence system shows up as `a loss of available regulated high voltage current, which is conventionally derived from the horizontal detlection stage. f i

As Vshown in Fig. 3, a voltage pulse wave of horizontal deectionlfrequency and positive going with respect to the point of reference potentiaL'shown as ground, is obtainedby means Vof a couplingcapacitor 107 and applied directlyY across thek variable vinductance Velement 104K which is connected in series with ashunting resistor 108K In the By placing the convergence system i system windings.

anda compensating capacitor 109K. As shown, the horizontal voltage pulse-wave is the same Wave that is conventionally-applied by means of a capacitivey element to the automatic gain control circuit. However, this pulse wave may be-,obtained from any other point in the horizontal deflection-wave output circuitthat such a gating pulse Wave is obtained. In addition to acting as a choke to prevent horizontal frequency components from entering the source of vertical frequency components, the trifilar winding 100 serves as a pulse wave transformer to induce the horizontal voltage pulse wave which is im:- presscd across the `winding 101 into the'trilar windings 102 and 103 for application to the other convergence circuits comprising the variable inductance elements 104G, 104B. shunting resistors ISG and 108B, and compensating capacitors 1096 and 109B. Alternately, an isolated trilar winding on the horizontal deflection wave output transformerH wouldserve as well and obviate the need for any coupling'capacitor. Each conductor of the trifilar winding would still serve as a path form vertical current vcomponents just as in the choke arrangement. v

-tilted by adding a sawtooth component to the current in vthe convergence system windings 41, 42 by means Vof tilt controlling capacitive elements 114. The sawtooth components for the red and green convergence system windings 41R, 42K, 41G, 42G are obtained by means of a coupling capacitor 116 connected tothe trifilar winding 101 of the trifilar choke 100, while that for the'blue con- .vergence system winding is shown with the tilt controlling capacitance element 114B connected directly to the trifilar winding 103. Since only capacitive elements are used, such cross-connections alord many cost reducing alternatives without detracting from the performance of the circuit in any way. The effect of adding the sawtooth component to the parabola is to increase the current on one side of the raster and decrease it on the other. By reversing the sawtooth polarity the action can be reversed. The same type of action occurs if the parabolic current Awave'is shifted in time with respect to the deflection and blanking period. This is effected by adding the pulse voltage wave required for tilting to the sawtooth voltage wave used for generating the parabolic wave. 'I'he overall result is an initially delayed sawtooth voltage wave which upon integration results in a tilted parabolic wave, requiring compensating tilt in the opposite direction. The degree of tilt is controlled by the amount of pulse added. The capacitive elements 109, 116, and 114, form voltage dividers by which the adjustment of the adjustable capacitive element 114 in each case determines the amount of pulse added to provide the required tilt. f

Since a horizontal frequency convergence component required by the blue gun of some tri-color kinescopes as conventionally operated is larger than that required by the red and green guns, the impedance of the blue convergence system windings 41B, 42B may be made lower so that like voltages can be used vfor Vthe three dellection In addition the parallel network comprising the capacitor 110 and the shunt resistor v111 may beV added, as shown, to the blue convergence windings circuit since the static compensating current is higher Vdue to the greater dynamic convergence voltage component. Those skilled in the art will determine Vthe values of components to be used in various applications ofthe vinvention from the teachings herein, however, the values of pertinent components listed below which were used in a successfully operated color television receiver having are given as' a Rei. No. Component Type or Value Tri-color Kinescope 21AXP22. Convergence system winding:

(red, green (blue only) Vertical oscillator and amplifier tubes. GBL?, Horizontal amplifier tube CD6. Horizontal pulse wave source. 800 to ground. Cathode resistor 2 0 o. Vertical Linearity Control. -1 ko. Vertical Integrating Inductor- 2.0 h. Vertical Parabola Control... 0-1 ko. Vertical Tilt Contro1. .0-100 o. Vertical Tilt Winding :t100 v.to

ground.

- Trlfilar choke 50 mh.

Horizontal Integrating Inductors.. 100-000 mh Blocking capacitors 50 mid. Dropping resistors-- 82 ko. Coupling capacitor. 0.1 mid. Series resistors 12 lro. Compensating capacitor 820 mi'. Shunt capacitor (blue only)- 0.05 mi. Shunt resistor (blue only)- 4700 o. Horizontal tilt control 100-600 mmf. kSeriescapacitor (red and green only) 560 mf.

Power supplied delivered approximately 400 volts between the points marked land ground, with y20() volts being delivered at the intermediate points marked +11 The invention claimed is:

l. A beam convergence circuit arrangement for multibeam kinescope the electron beams of which are deilected in two directions normal with respect `to each other, includinga plurality of convergence windings through which 'currents of substantially -parabolic waveform of frequency corresponding to electron beam deflection in one of said directions are desired, a plurality of series circuits each comprising an inductance element and a resistance element connected in series, means to apply a voltage pulse train of recurrence rate corresponding to said deflection in said one direction across said series circuits, and means to couple said windings individually across said resistance elements in such manner that the voltage produced across each resistance element by said pulse train is impressed upon its associated winding.

2. A beam convergence circuit arrangement for multibeam kinescope the electron beams of which are deilected in two directions normal with respect to each other, including a plurality of convergence windings through which currents of substantially parabolic waveform of frequency corresponding :to elect-ron beam deflections in one of said directions are desired, a plurality of series circuits each comprising an inductance element and a resistance element connected in series, means to apply a voltage pulse train of lrecurrence rate corresponding to said deflection in said one direction across said series circuits, and means including capacitive reactance elements to couple said windings `individually across said resistance elements.

3. A beam convergence circuit arrangement for an internal convergence pole-piece type multi-beam kinescope the electron beams of whichare deected in two directions normal with respect to each other, including a plurality of convergence pole-piece exciting windings through which currents of substantially parabolic waveform of frequency corresponding to electron beam deilection in one of said directions are desired, a plurality of series circuits each comprising an adjustable inductance element and a resistance element connected in series, means to apply a voltage pulse train of recurrence rate corresponding to said deection in said one direction across said series circuits, and means including capacitive reactance elements to couple said windings individually across said resistance elements, the amplitude of sai-d parabolic current waveform being varied by adjustment of said inductance element.

4. A beam convergence circuit arrangement for an inicrnal convergence pole-piece type multi-beam kinescope l0 the electron beams of which are deflected in two directions normal fwth respect to'each other, including a plurality of convergence pole-piece exciting windings through which currents of substantially parabolic waveform of frequency corresponding to. electron beam ,deection in one of said directions are desired, a plurality of series circuits each comprising an inductance element and a resistance element connected in series, means to apply a voltage pulse train of Irecurrence rate corresponding to said deflection in said one direction across said series circuits, means including capacitive reactance elements to couple said windings individually across said resistance elements, and

means to apply a portion of -said'voltage pulse train across each of said windings.

5. A beam convergence circuit arrangement for an internal convergence pole-piece type multi-beam kinescope the electronbeams of which Vare deflected in two directions normal with respect to each other, including a plurality of convergence pole-piece exciting Iwindings through which aV current of substantially parabolic waveform of frequency corresponding to electron beam deilection in one of said ldirections is desired, a plurality of series circuits each comprising an inductance element and a resistance element connected in series, means to apply a pulse voltage train of recurrence rate corresponding to said deection in :said one direction across said series circuits, means including capacitive reactance elements individually to couple said windings across said resistance elements, and means including other capacitive reactance elements individually operative to conjunction lwith the rst said capacitive reactance elements to apply a portion of said pulse voltage train individually to ysaid windings. v

y6. A bea-m convergence circuit arrangement for an internal convergence pole-piece type multi-beam kinescope the elect-ron beams of which are deflected in two directions normal with respect to each other, including a plurality of convergence polepiece exciting windings through which a current of substantially parabolic waveform of frequency cor-responding to electron beam deection in one of said directions is desired, a. plurality of series circuits each comprising an adjustable inductance element and a resistance element connected in series, means to apply a pulse voltage train olf recurrence rate corresponding to said deflection in said one direction across said series circuits, means including capacitive reactance elements individually to couple said windings across said resistance elements, and means including adjustable capacitance elements individually operative in conjunction with the rst said capacitive reactance elements to apply a portion of said pulse voltage train individually to said windings, the amplitude of said parabolic current waveform being varied by adjustment of said inductance element and the tilt being varied by adjustment of rsaid capacitance elements.

7. A beam convergence circuit arrangement for an internal convergence pole-piece type multi-beam kinescope the electron beams of which are deiiected in two directions normal with respect to each other, including a plurality of convergence pole-piece exciting windings through which currents of substantially parabolic waveforms of frequency corresponding to electron beam deection in both `of said directions are desired, a plurality of series circuits each comprising an inductance element and a resistance element connected in series, means including a trilar winding individually to apply a voltage pulse train of recurrence rate corresponding to said deflection in said one direction across said series circuits, means including capacitive reactance elements individually to couple said windings across said resistance elements, means includingadjustable capacitive reactance elements to apply a portion of said voltage pulse train across said windings, an inductive reactance element and a plurality of variably tapped resistance elements connected in common to said inductive reactance element, means to apply a sawtooth wave of recurrence rate corresponding to il deflection in the other direction between said inductive reactance element andv each of said variably tapped resistance elements to produce a substantially'parabolic voltage wave across the last said elements, a plurality of variably tapped resistive elements having taps individually connected to said triiilar winding, means to apply a pulse train recurrence rate corresponding to deflection in said otherdirections across said resistive elements, and means coupling said convergence windings to the taps of said A variably tapped resistance elements.

8. A beam convergence circuit arrangement for a multibeam kinescope, comprising a vertical deflection wave circuit including an output transformer having a convergence winding with an intermediate tap -being electrically at a point of xed reference potential and midway between the terminals of. said winding, and an amplifying electron discharge tube having anode and cathode electrodes connected to the primary winding of said transformer through an unbypassed resistance element, a plurality yof variably tapped resistive elements connected between said terminals of said convergence winding, an inductor having one terminal `connected to the one terminal of said resistance element, a plurality of variably tapped resistance elements connected :between the other terminal of said inductor and said point of fixed reference potential, a horizontal deflection wave output transformer having a winding, a trilar choke having plurality of conductors having terminals connected individually to the taps of said resistance elements and being coupled to a point on said horizontal transformer winding, an adjustable inductor, a resistor and a capacitor connected in series with each of the conductors of said tritlar choke, adjustable capacitors connected across each of the series vcircuits comprising said adjustable inductor and resistor,

lil

a plurality of convergence system windings connected individually between junctions of said adjustable inductors and resistors and the taps of said resistance elements by blocking capacitors, connections between each of said capacitors in said series circuits and the junctions between said blocking 'capacitors and said convergence windings, and resistors connected between a point of fixed energizing potential and the individual junctions `of said blocking capacitors and said convergence system windings.A

9. A beam convergence circuit arrangement for multibeam kinescope the electron beams of which lare deected in two directions normal with respect to each other, including a plurality of convergence windings through which currents of substantially parabolicV waveformbf frequency corresponding to electron beam deflection rin one of said directions are desired, a plurality of series circuits each comprising an inductance element land a resistance element connected in series, means to apply a voltage pulseftrain of recurrence rate corresponding to said deflection in said one direction across said series circuits to produce substantially sawtooth voltage waves `zacross said resistance elements, and means to Icouple said windings individually across said resistance elements in'such manner that said sawtooth voltage Waves 5appearing across vsaid resistive elements serve to induce substantially parabolic current waves in said windings.

References Cited in the le of this patent UNITED STATES PATENTS

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