US2697743A - Electron beam deflection system - Google Patents

Description

Dec. 2l, 1954 A. c. SCHROEDER 2,697,743

ELECTRON BEAM DEFLECTION SYSTEM Filed Aug. 15, 195o 2 sheets-sheet 1 R. Y h O E f MVMNWW (4.. w 5 n U .kmuw -k w l w 12H1 vw num m L|.| .mw .mm w El f mmw u Ew u www k N@ LmwI E SQ A E@ m3 Q y m A K wi wm m A. c. scHRoEDER 2,697,743

ELECTRON BEAM DEFLECTION SYSTEM 2 Sheets-Sheet 2 Dec. 21, 1954 Filed Aug. 15, 195o INVENTOR s United States Patent O ELECTRON BEAM DEFLECTION SYSTEM Alfred C. Schroeder, Feasterville, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application August 15, 1950, Serial No. 179,460

Claims. (Cl. 178-S.4)

This invention relates to deflection systems for cathode ray tubes. It has particular reference to systems for dellecting electron beams of kinescopes used in television systems.

The deliection of an electron beam of a cathode ray tube over a luminescent screen or other target electrode frequently is done in a manner to scan a substantially rectangular raster. Whether or not the raster is truly rectangular depends primarily upon the creation of two beam-deliecting component tields at right angles to one another. Any departure from this relationship results in a corresponding departure from the rectangular form of the scanned raster.

For many purposes, in television particularly, it is desirable to produce a scanned image raster which is substantially rectangular. Such a result is especially necessary in color television systems where a plurality of electron beams of one or more kinescopes are used. The beams `are deflected over target electrode structure to reproduce an image in a number of its component colors. Good color registration may be obtained only if the rasters scanned by the beams are uniform in size and shape.

lt is an object of the present invention, therefore, to provide an improved deflection system for an electron beam of a cathode ray tube, whereby the raster scanned by the beam has a predetermined shape irrespective of the relative orientation of the held-producing components of the deliecting system.

Another object of the invention is to provide an improved electron beam-deecting system for each of a plurality of electron beams of one or more cathode ray tubes, whereby the respective image rasters scanned by the beams may be optically combined in substantially precise register.

Another object of the invention is to provide an improved electron beam-detlecting system for use in a color television image-reproducing system embodying a plurality of kinescopes, whereby the images formed on the kinescope screens all have substantially the same geometric shapes.

In the apparatus with which the invention is used, there is provided a deflecting system for an electron beam of a cathode ray tube. The deflecting system consists of two field-producing components. One of these components is energizable to deilect the beam substantially in a horizontal direction and the other substantially in a vertical direction. Means are provided for energizing these components with sawtooth wave energy. In accordance with a feature of this invention, there is provided means for energizing one of the field-producing components with supplemental wave energy which varies as a function of the energization of the other component. By such means there may be developed two beamd eflecting component fields which are substantially at right angles to one another. Accordingly, the beam may be deflected to scan a raster at a target electrode, such as a luminescent screen of a kinescope, which is substantially rectangular. 4

Further, in accordance with this invention, a plurality of electron beams of one or more kinescopes may be used to reproduce the component colors of an image.- In such a case, certain ones or all of the electron beams may be provided with deflecting systems of the character described. Suitable adjustment of the dellecting systems may be made to control the sizes and shapes of the respective 4rasters formed on the kinescope target elec- "ice trode or screen structure. Uniformity of the sizes and shapes of these rasters will enable the optical combination of them to form a composite image in which all of the component color rasters are in substantially precise registration.

'lhe novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization 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 l is a block diagram of a color television signalreceiving and image-reproducing system embodying oneform of the invention;

Figure 2 is a schematic circuit diagram of a component of the system shown in Figure l by which the supplemental deecting wave energy is derived and coupled into the main deection circuit; and,

Figure 3 is a fragmentary block diagram of another form of the invention.

Reference tirst will be made to Figure 1 of the drawings. This embodiment of the invention includes a conventional television receiver 11. Tne general detalls of such a receiver are well-Known to tnose sltiiled in tne art. For the present purposes, therefore, it may oe considered to include the necessary apparatus for amplirying and detecting a television carrier wave conveying. ine video signal and system control signals such as horizontal and vertical synchronizing pulses.

'lne present invention is not necessarily limited for use with any particular type color television system, lt is particularly userul with systems or the simultaneous type such as disclosed in U. S. Patent No. Z,.t.5. ,l0 granted November 23,. 1945, to A. N. Lioldsmith and titled "Television System. ln such a system ine video signals representing individually the ditierent component image colors are transmitted effectively over tliree different channels. Another type 0I system in wlllch the invention may be used torms the suoject matter ot' a copendiug application of John Evans, Serial No. lll,32$4, tiled August zo, w49, and titled "Color 'lelevision." ln

ysuch a system video signals representing tne dillerent' colors or eacrl elemental image area are elrectively transmitted and received consecutively.

Accordingly, it will be assumed that, regardless of the particular type or color television system used, there are made available at me receiver, video signals respectively representative or' a plurality of image colors. ror trle purpose primarily or illustration, lt is Iurtlier assumed that the present system is tlie usual three color one. lli this case the color video signals will ne representative respectively of trie red, blue and green component color images. 'l'he individual video signal trains, tneretore, may oe considered to be conveyed separately rrom tile television receiver 1i to the reproducing apparatus by red, blue and green video signal channels lz, la alld 14, respectively. 'l ne video signal channels terminate at red, blue and green Kinescopes lo, 16 and M, respectively. lt will be understood that the video signals are impressed conventionally upon tne intensity control electrodes of the electron guns of these kinescopes, Accordingly, the intensity ot the electron beams produced by tliese guns is modulated in accordance with the particular video signals impressed thereon.

'lhe color kinescopes 15, 16 and 17 are provided with systems for deilecting the respective electron beams thereof. It will be understood that these deecting systems may be either electromagnetic or electrostatic. 'lhe invention is equally applicable to either type of system. ln the illustrative embodiments of the invention disclosed herein, electromagnetic beam-deflecting systems have been shown. Each consists of a vertical and a horizontal coil. These coils are mounted together about the neck of the kinescope in a conventional manner to form the usual deection yoke. Since such yoke structures are well-known, they have been shown diagrammatically in vthe drawings. The red kinescope 15 is provided with vertical and horizontal deecting coils 18 and 19, respectively. Similarly, the blue kinescope 16 has vertical and horizontal deilecting coils 21 and 22, respectively. Vertical and horizontal deflecting coils 23 and 24, likewise, are provided for the green kinescope 17. The manner in which the horizontal and vertical coils of these deflecting systems are energized will be described presently.

In order to produce a composite image of the three component colors produced by the red, blue and green kinescopes 15, 16 and 17, respectively, there is provided a suitable optical system. The particular type of optical system which is employed is immaterial. For the purpose of the present disclosure, therefore, there is provided adjacent the luminescent screen of the green kinescope 17 4a reflecting device such as a mirror 2S. Adjacent to the screen of the blue kinescope 16 a colorselective mirror, such as a .dichroic reflector or mirror 26, is provided. The properties of dichroic rellectors are well-known and will not be described in detail here. Sufice it to state that the dichroic mirror 26 has the property of rellecting blue light and of transmitting green light. A similar dichroic rellector 27 is mounted adjacent to the screen of the red kinescope 15. It has the property of rellecting red light and of transmitting blue and green light. Finally, there is provided a reflector such as a plane mirror 28 mounted in such position as to rellect all of the red, green and blue light incident thereon. This light may be projected onto a viewing screen or the kinescope screens may be viewed directly from the mirror 28. lt will be understood that the kinescopes and optical components should be relatively located to Iequalize the lengths of the light paths from the kinescope screens to the mirror 28. By such means good optical registration may be effected.

In order to control the deflection of the Velectron beams of the kinescopes i5, 1.6 and 17 the television signal receiver 11 is coupled to a synchronizing signal separator 29. This apparatus may be entirely conventional. lts purpose is to separate the synchronizing signal pulses from the video signals. yIt further functions to separate the horizontal and vertical synchronizing pulses from one another. Accordingly, it Vmay :be considered to have two output circuits. In one output circuit .the Lhorizontal synchronizing pulses, such as indicated at 30 are developed. In the other youtput circuit vertical synchronizing pulses, such as shown at 3i, are developed.

The lsynchronizing pulses 30 and 31 are impressed upon horizontal and vertical 4deilection generators 33 and 34. This apparatus also lmay be conventional. Each of the generators functions -to produce sawtooth wave energy. The `horizontal `dellection `generator 33 ldevelops a sawtooth wave 35 having ,the horizontal or 'line-scanning frequency. Similarly, the vertical deflection generator produces a sawtooth wave 36 Ihaving ythe vertical -or fieldscanning lfrequency.

The output of the vertical Ideiiection generator 34 is coupled in parallel 'to `corresponding .terminals of Athe vertical deflection =coils 18, 2l and 23. The `other terminals of these coils are connected to ground. It will be understood, however, .that in -practice these terminals preferably are connected to individual vertical centering controls.

Similarly, the horizontal deflection generator 33 is-coupled to corresponding terminals .of -the Ahorizontal deflection coils 19, 22 and 24. 'The 'other terminals of these horizontal deflecting-coils are returned to ground -through individual compensating apparatus. Specifically, the -horizontal deflecting coils 19, 22 and 24 are `coupled respectively to compensating apparatus 37, 38 and 39. This apparatus lwill be 'understood `to include individual horizontal centering circuits and means for developing supplemental wave energy varying as a function of -the -vertical deliecting wave-energy. The-details of typical `compensating apparatus will be described Asubsequently lin connection with -Figure 2 of the drawings. For the present purpose, itis yto be -noted `that the compensating apparatus 37, 3.8 and 39 .is coupled for control to an intermediate point vof vthe vertical dellection generator 34. At such a point there are developed from the synchronizing pulses such as.31, .well-formed pulses which may be yintegratedto produce the sawtooth waves such as 36. These well-formed pulses are used to control .the .compensatingapparatus and are lindicated at Y4t).

Any misalignment of the horizontal and vertical coils forming adetlection yoke vfor any :of .the kinescopes will result in 'the :scanningof arrasterat the kinescope screen which ,is ,not entirely rectangular. Consider, for example, the kinescope y15. Unless the vertical and horizontal coils 18 and 19, respectively, are mounted about the neck of the kinescope so as to produce horizontal and vertical beam-deflecting fields which are precisely at right angles to one another, the deflection of the beam over the screen of the tube will result in the formation of a nonrectangular raster. All opposite sides of the raster, nevertheless, will be substantially parallel. However, in accordance with this invention, there is introduced in the horizontal coil 19 a supplemental wave of a particular form and magnitude and having the vertical dellecting frequency. in this manner, the effect of any misalignment of the coils 18 and 19 may be overcome. Since each of the kinescopes is provided with deflection circuits of this character, it is seen that suitable individual control of the compensating wave energy wil enable the production of rasters at the kinescope screens of similar shapes and sizes. Consequently, they may be combined by an optical system to produce a composite color television image in which the component color images all are in substantial registration.

It is to be noted that the compensating circuits generally used to correct for keystone or similar types of raster distortion where opposite sides are not parallel, are inefective for present purposes. A typical Keystone correction circuit is shown in U. S. Patent No. 2,481,839, granted September 13, 1949, to A. N. Goldsmith entitled Color Television. Such prior art compensating circuits do not provide the necessary generator of supplemental wave energy to be additively combined with the deflecting wave energy.

Referring now to Figure 2 of the drawings there will be described in some detail typical compensating apparatus for developing the supplemental wave energy. The compensating apparatus 37 used in conjunction with the red kinescope 15 has been chosen for illustration. It will be understood that similar apparatus may be used with the other color kinescopes. The apparatus consists of a wave-forming circuit including an electron tube 41. The control grid 42 .of this tube is coupled by a capacitor 43 and a grid leak resistor 44 to the vertical deliection generator 34. The suppressor grid 45 is conventionally coupled .to the grounded cathode. The screen grid 46 of this tube is connected to the junction point between voltage divider resistors 47 and 48. These resistors are connected between a point of positive potential and ground. The screen grid also is by-passed to ground by a capacitor 49. The tube 41 serves primarily to discharge a storage capacitor periodically in a manner to be described presently.

The anode of the discharging tube 41 is `coupled to a storage capacitor 51. Such a connection is for the purpose of periodically discharging the capacitor through the tube 41. The capacitor is charged through a circuit which includes a resistor S2. This resistor is connected to a point of suitable positive potential. ln the present case this potential is derived from a potentiometer 53 forming a part of a voltage divider which also includes a resistor 54. The voltage divider is .connected between a source of positive potential, and ground, as shown.

The storage capacitor 51 also is coupled to the control grid S5 of another' electron tube 5.6 provided in the waveforming circuit. Space .current for Athe tube 56 is derived from a source of .positive potential and is conducted through a load resistor 57 coupled -to 'the anode ond also througha cathode resistor.

The wave-,forming .circuit operates in lthe usual manner. The storage capacitor 51 is charged at a relatively slow .rate which is determined primarily by its value and that of the resistor 52. Periodically, lthe-discharging Vtube 41 yis rendered .operative -under ythe `control of the pulses 4t) derived from the verticaldellection generator 34. Operation of this tube, whereby .it becomes conducting, provides a relatively low impedance discharge path for the storage capacitor 51. The discharge of this capacitor, therefore, is at a Vrapid rate. Accordingly, there is developed at the lungrounded terminal ofthe capacitor a substantially sawtooth voltage wave which is impressed upon the tube 56 for suitable amplification.

The specific details ofthe wave-forming circuit are not to be considered yas limiting the scope of the invention. The illustratively disclosed circuit functions to develop a wave having a substantially sawtooth shape. It will be understood by those skilled in Ithe art that other wave forming circuits may -be used within the scope of the invention for the development of waves having other desired forms. One other wave form which may be developed for use in a system of the character described is a parabolic wave.

The sawtooth wave produced at the anode of the tube 56 is impressed upon an output electron tube 59 by means of a coupling including a capacitor 61 and a resistor 62. The control grid 63 of the tube 59 is connected to a variable point on the input resistor 62. The screen grid 64 of the tube 59 is coupled conventionally to a source of positive voltage. Similarly, the anode of the tube is connected to a positive voltage source through the primary winding 65 of an output coupling transformer 66. A relatively small resistor 67 is included in the cathode circuit of the tube 59. The transformer 66 also is provided with a secondary winding 68 in which the sawtooth wave energy is produced in a predetermined polarity dependent upon the connections of the primary and secondary transformer windings.

The secondary winding 68 of the coupling transformer 66 is connected to a polarity-reversing switch 69 to which also is coupled an output resistor 70. The resistor 70 is included in series with the horizontal deflecting coil 19 in its return circuit to ground. As previously described, this ground-return circuit includes a centering control which is diagrammatically illustrated as a potentiometer 71. The resistive portion of the potentiometer is connected between a point of positive voltage and ground.

The sliding contact of the potentiometer is connected to the resistor 70 and also is bypassed to ground by a capacitor 72.

It is seen, therefore, that the sawtooth voltage wave developed by the compensating apparatus 37 at the vertical deflecting frequency is combined with the horizontal deflecting sawtooth energy derived from the generator 33 to energize the horizontal deflecting coil 19. The magnitude of the compensating wave may be controlled by adjustment of either of the sliding contacts associated respectively with the resistors 53 or 62. The polarity of the compensating sawtooth wave is determined by the.

position of the reversing switch 69. It will be appreciated that a misalignment of the vertical and horizontal deflecting coils in one sense requires a compensating wave of one plurality and misalignment in an opposite sense requires a compensating wave of opposite polarity.

A system of the character shown in Figure 1 ordinarily will be used mostly in those cases where each of the deflecting systems for the diiferent electron beams is misaligned to the extent that the departure of thescanned image raster from a rectangular form is enough to be objectionable. It may be that the deflecting system for no one of the electron beams is precisely enough aligned to produce an exactly rectangular raster. However, it often will be found that at least one of these systems will be unobjectionable in this respect. In such a case it may be desirable to omit any compensating apparatus for this one deflecting system.

Figure 3 of the drawings, to which reference now will be made, shows diagrammatically such a system. It is assumed that the vertical and horizontal deflecting coils 18 and 19 associated with the red kinescope 15 are aligned satisfactorily relative to one another to produce a scanned image raster which is substantially rectangular. It may also be assumed that the deflecting systems of the blue and green kinescopes 16 and 17, respectively, are similarly aligned. However, if the misalignment of the deecting system of the blue kinescope 16, for example, is in a sense opposite to any misalignment of the deecting system for the red kinescope 15, the resultant mis-registration of the red and blue component images may be sufficient to be objectionable. In such a case it merely is necessary to effect compensation of one of the deliecting systems. The image rasters scanned correspond in shape and size to the other image raster.

Accordingly, in Figure 3 the vertical and horizontal deflecting coils 18 and 19 associated with the red kinescope are energized solely by the sawtooth waves derived respectively from the vertical and horizontal de-l ection generators 34 and 33. The horizontal deflecting coil 22 associated with the blue kinescope 16 is further energized by supplemental wave energy derived from the compensating apparatus 38. Likewise, the horizontal deecting coil 24 associated with the green kinescope 17 is additionally energized by supplemental wave energy produced by the compensating apparatus 39.

In view of the foregoing description of the operation Fw 0 of the apparatus of Figure l, taken in connection with the detailed disclosure of the compensating apparatus ofi Figure 2, the operation of the system of Figure 3 will be apparent to those skilled in the art. In this case, it will be understood that the compensating apparatus 38 is adjusted suitably to produce a scanned image raster by the electron beam of the blue kinescope 16 which conforms substantially to the shape and size of the raster scanned at the red kinescope 15. A similar adjustment of the compensating apparatus 39 is elfected to produce the desired uniformity of the size and shape of the raster scanned at the green kinescope 17.

The compensating apparatus shown in detail in Figure 2 is especially adapted to produce supplemental wave energy having a substantially sawtooth shape. However, it will be understood to be within the scope of the present invention to provide apparatus for developing parabolic or other suitable wave shapes.

Furthermore, it also is contemplated to be within the scope of the invention that supplemental wave energy at the horizontal deilecting frequency may be introduced in the energizing circuits for the vertical deflecting components. Also, it will be apparent that the principles underlying the present invention may be successfully employed with a single deecting system to produce a substantially rectangular or other desired shape of scanned raster.

In view of the two illustrative embodiments of the invention disclosed herein, it will be evident that the invention may be used successfully not only in color television systems, but also in black and white television systems. Moreover, it may be used in systems such as those including cathode ray Oscilloscopes of a nature similar to the kinescopes of television systems. When the invention is to be used in conjunction with a plurality of deflecting systems, the supplemental wave energy may be supplied to all of the deilecting systems, in the case where it is desired to effect a compensation of all of the scanned rasters. Alternatively, where it is desired merely to make all of the rasters uniform, the supplemental wave energy may be impressed upon less than all of the deflecting systems. For example, it may be applied to all but one of the deilecting systems.

It also will be evident, in view of the present disclosure, that the invention is not limited necessarily for use in systems embodying a plurality of cathode ray tubes. Instead, the invention may be used in conjunctionwith a cathode ray tube having a composite target electrode structure and separate means to develop a plurality of electron beams. A representative form of such cathode ray tube apparatus is disclosed in U. S. Patent 2,491,839, granted September 13,1949, to Alfred N. Goldsmith and titled Color Television.

Furthermore, it will be appreciated by those skilled in the art that the invention may be employed beneficially in conjunction with the deflecting systems provided for video signal-generating tubes as well as with image-reproducing tubes as illustratively disclosed herein.

The nature of the invention may be determined from the foregoing disclosure of a numberof illustrative embodiments thereof. The scope of the invention, in view of the disclosure and the immediately preceding paragraphs, is set forth in the appended claims.

What is claimed is:

l. In a color television system, cathode ray tube apparatus for reproducing an image in a plurality of component colors, said apparatus including means to develop an electron beam for each of said component image colors, and target electrode structure to be scanned by said beams, respective systems for deliecting said beams to scan individual rasters of said target electrode structure, each of said dellecting systems including individual components for effecting horizontal and vertical deflections of said respective beams, generators of deecting wave energy at horizontal and vertical frequencies coupled respectively to normally energize said horizontal and vertical deflection system components, compensating ap paratus including a generator of supplemental wave energy at one of said beam-deflecting frequencies, and means coupling said compensating apparatus to at least one of that group of deilecting system components which normally is energized at the other of said beam-deflecting frequencies in a manner to additively combine said supplemental energy and said normal beam-deflecting energy,

thereby to produce uniformity .0f Shape and ,Size f Said scanned .rasters- '2, Color television apparatus as defined in claim 1 wherein, said compensating apparatus includes one of said supplemental wave energy generators for each of said detiecting systems.

3. Color television apparatus as defined in claim l `wherein, said compensating pparatus includes fewer of said supplemental wave energy generators than there are deecting .Systems provided.

4, Color television apparatus as defined in claim 1 wherein, said compensating apparatus includes one less of saidsupplemental wave energy generators than there are deneeting systems provided.

5, Color television apparatus as defined in claim 1 wherein, said cathode ray tube apparatus comprises a plurality of kinescopes, each kinescope having an electron gun to develop one of said plurality of electron beams, and ksaid target ,electrode structure comprising a luminescent screen :associated with each or' said electron guns.

6,. In a color television system, a cathode ray .tube for each of a plurality of Acomponent image colors, a luminescent screen for each of said tubes, an optical system to combine Vthe images formed on said screens, each of said tubes also having a system for dcecting an electron beam to scan an image raster at each of said screens, said deliecting systems each including individual components for effecting horizontal and vertical beam deflection, wave generators coupled respectively to energize said horizontal and vertical deecting system components, and generators of compensating wave energy at vertical deecting frequency coupled to certain ones of said horizontal d'eilecting components in a manner to additively combine said compensating wave energy with said horizontal .deflecting vwave energy, thereby to produce uniformity vof shape and size of said scanned image rasters.

7. A system for deiiecting the electron beam of a cathode ray tube comprising, individual horizontal and vertical beam-deliecting components, individual generators to produce deflection wave energy respectively at horizon tal .and vertical scanning frequencies, means coupling said generators respectively Ato said beam-deflecting components, a generator of supplemental wave energy at one of said scanning frequencies, and `means additively coupling said supplemental wave energy generator to that one of said vbeam-deiiecting `components which normally is energized at the other `of said scanning frequencies.

'8. In a system 4for .electron beam deflection in .cathode ray .tube apparatus, two cathode ray tubes, each having means :to develop an electron beam, a deflecting system for .each of said Itubes including individual 'horizontal and vertical beam-deecting components, means to develop and impress respectively upon said :beam-deflecting components wave energy at horizontal and vertical scanning frequencies, means to develop supplemental wave energy at one of said scanning frequencies, and means additively coupling said supplemental wave energy-generating means to those of said `beam-deiiecting components which normally are energized at the other of said scanning frequencies.

9. :Cathode ray tube apparatus including, means to develop two electron beams, individual horizontal and vertical beam-deflecting components for each of said beams, wave-generating means coupled to said beam-deflecting components to energize said beam-deflecting com- Ponente at horizontal and vertical scanning frequencies respectively, means tofdevelop supplemental wave energy at said vertical scanning frequency, and means additively coupling said supplemental wave energy-generating means to one of said horizontal beam-detlecting components to additionally energize said one horizontal beam-deiecting component as a function of said vertical scanning frcf quency.

10. Cathode ray tube apparatus including, means to develop a plurality of electron beams, individual horizontal and Vertical beam-deecting components for each of said beams, wave-generating means coupled to said beam-de ilecting components to energize said beam-deiiecting components respectively at horizontal and vertical scanning frequencies, means to develop supplemental wave energy at said vertical scanning frequency, and means additively coupling said supplemental wave energygenerating means to' predetermined ones of said horizontal beam-defiectng components to additionally energize said predetermined horizontal beam-.deecting components at said vertical scanning frequency.

l1. Cathode ray tube apparatus as defined in claim 10 wherein, said supplemental wave-generating means is additively coupled to all of said horizontal beam-detiecting components, whereby they are additionally energized at said vertical scanning frequency.

12. Cathode ray tube apparatus as defined in claim l0 wherein, said supplemental wave-generating means is additively coupled to all but one of said horizontal beamdeecting components, whereby they are additionally energized at said vertical scanning frequency;

i3. Cathode ray tube apparatus as defined in claim 10 wherein, said supplemental wave-generating means is additively .coupled to two of said horizontal beam-deflectlng components, whereby they are additionally energized at said vertical scanning frequency.

14. Cathode ray tube apparatus as kdefined in claim 10 wherein, Athree electron beams are developed, and said supplemental wave-generating means is additively coupled to two of said horizontal beamadeflecting components, whereby they are additionally energized at said vertical scanning frequency.

15. 'Cathode ray tube apparatus as defined in claim 10 wherein, three kinescopes are provided, said electron beam-developing means serving to generate individual electron beams respectively for said kinescopes, and said supplemental Wave-generating means is additively coupled to at 'least one of said horizontal beam-deecting beam components, whereby it is additionally energized at said vertical .scanning frequency.

References `Cited `in the -ile of this patent UNITED STATES PATENTS Number Name Date 2,389,646 Sleeper a z Nov. 27, 1945 2,481,839 Goldsmith Sept. 13, 1949 2,568,543 lGoldsmith Sept. 18, 1951

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