US2764628A - Television - Google Patents

Description

Sept. 25, 1956 J. E. BAMBARA 2,764,528

TELEVISION Filed March 19,. 1952 17 FIG.I Q/ 146:\14B Q 4 Sheets-Sheet l RECEIVER CIRCUIT VIDEO CHANNEL DEFLECTION CHANNEL GB RGBRG FIG. 3 f L 9 26 a 14/? M a ATTORN 4 Sheet-Sheet 2 J. E. BAMBARA TELEVISION 32a 1 WW AA 1 32a J 'JJ-| am: U- l I 33 I .1

RED 9 Se t. 25, 1956 Filed March 19, 1952 Sept. 25, 1956 J. E. BAMBARA TELEVISION 4 Sheets-Sheet 3 Filed March 19, 1952 FIG. 8

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FlGJOcI INVENTOR (Ins-(pi if jaw/dare Unite 2,764,628 TELEVISION Joseph E. Bamhara, Brooklyn, N. Y., assignor to Columbia Broadcasting System, Inc, New Yorir, N. Y., a cor poration of New York Application March 19, 1952, Serial No. 277,500 27 Claims. ci. 1-7s--s.4

States Patent At the present time there have been a number ofproposals for tri-color cathode-ray tubes in which pictures are reproduced in three primary colors on substantially the same area of the viewing screen. In some tubes of this type a perforated mask is placed in the path of the electron stream to the viewing screen and in another type a pair of intermeshed Wire grids is arranged in the path of the electron stream. In the mask type of tube, three electron guns are commonly employed so that the three electron beams passthru a given aperture in the mask at different angles to impinge on three separate elemental areas of the viewing screen, and the three elemental areas fiuoresce in three primary colors, respectively. A single gun version has also been proposed in which a deflecting field is employed to cause the electron beam to pass thru the mask atthree different angles successively, thereby impinging on the three elemental areas of different color.

In the case of the grid type of tube, one electron gun has been suggested and the two sets of grid Wires energized so that the electron beam is focused and deflected to elemental screen areas of diiferent primary color.- In this case also, a three-gun version has been proposed in which the directions of the electron beams determine which color phosphors are energized, and the grid is employed to focus the several beams.

In the three-gun versions of tubes of this general type, a problem of registering the different primary color images arises. If the several electron guns are parallel and common deflecting fields are employed, the corresponding three scanning rasters will be displaced at the viewing screen unless additional means are employed to produce registration. One expedient which has been employed is to produce so-called convergence fields by an electrostatic or electromagnetic lens system so that corresponding points in the three-color images will coincide on the viewing screen. In general the amount of convergence required varies with the position of the picture points and dynamic convergence signals are required which can be quite complex. Any errors in convergence can. produce serious misregistration in the color picture. In the single-gun versions wherein a deflecting field is applied to cause the electron beam to impinge on the viewing screen successively from diiferent directions, a similar problem of registration arises.

Several different color scanning methods have been proposed in the past, and can be employed with one or more of the tubes described above. The scanning methods can be divided broadly into simultaneous and vsequential categories, depending upon whether the several primary colors are reproduced simultaneously or suc- 2 essively. The sequential category can be sub-divided into field, line, and dot sequentiai arrangements, wherein the several primary colors alternate at field, line or dot frequency, respectively. Other specific scanning methods have been proposed but the above suffices for explaining the-present invention.

In simultaneous scanning systems several electron beams corresponding in number to the primary colors coexist and are simultaneously deflected over the reproducing screen inv horizontal and vertical directions by the same scanning fields. Consequently any convergent signals employed to effect registration are applied simultaneously to all three beams. Since the three beams will in general not occupy the same region. in the convergence field, it is difiicult to obtain precise registration.

In the sequential systems the scanning beams corresponding to diiferent colors exist sequentially, and consequently the scanning fields affect only one scanning beam at. a time. It is thus possible to use somewhat different convergence signals for scanning, beams corre sponding, to different colors in order to obtain more perfoot registration, although the necessary circuitry may become quite complicated.

In accordance with the present invention the relative phase of the video signal waves and corresponding deflection waves are changed from color to color in order to effect the desired registration. In the case of simultaneous systems where common deflecting fields ars employed for the several beams, the video signal Waves corresponding to the diflerent colors are delayed by different amounts. In the case of sequential systems the change in relative phase can be produced in the same manner, that is by appropriate delay of the video signals. However, in the case of line and field sequential systems, change in phase can also be produced by delaying the deflection waves rather than the video waves.

Usually common deflection means such as a single set of deflecting coils or plates are employed. for the several beams even in sequential type systems. Inasmuch asthe several beams are not likely to traverse exactly the same portions of the deflecting fields during their deflection, the scanning rasters may not be identical, In accordance with the present invention such distortion can often be reduced or eliminated by the use of variable delay to produce a variable change in phase during the reproduction of one or more primary colors.

The invention will be more fully understood by a consideration of the following detailed description thereof taken in conjunction with drawings in which:

Fig. 1 illustrates a three-gun mask-type tri-color tube with which the invention may be employed;

Fig. 1(a) is a detail illustrating a single gun with deflection to produce three axially-separated beams;

Fig. 1(b) is a block diagram of a general receiver arrangement for the tube of Fig. 1; i

Fig. 2 is a detail further explaining the construction of the tubes of Figs. 1 and 1(a);

Fig. 3 illustrates details of a tube in are triangularly arranged Fig. 4 illustrates the use of delay to register images whose centers of deflection are on a line;

Fig. 5 is an explanatory diagram similar to Fig. 4 but in which the centers of deflection are triangularly arranged; 1

Fig. 6 is a diagram showing how the relative phase may be changed by delaying either video or deflection waves;

Fig. 7 illustrates a simple circuit for producing diflierent delays of a video signal;

Fig. 8 is a circuit for the delay of synchronizing sigwhich the guns 0 nals;

Fig. 8(a) illustrates gating Waveforms used in Fig. 8;

placed positions of beam 23 thus correspond to the J) observed in tubes such as shown in Fig. 1 and the correction thereof;

Fig. is a circuit diagram for producing variable delay to reduce the type of distortion shown in Fig. 9(a);

Figs. 10(a), (b) and (c) are details showing certain waveforms of the circuit of Fig. 10; and

Fig. 11 is a block diagram illustrating a general arrangement for delaying deflection waves.

Referring now to Fig. 1 a tri-color cathode-ray tube is shown comprising an evacuated envelope 12, of glass or metal, with an appropriate base 13. In the neck of the tube are mounted three electron guns 14G, 14B and 14R which generate electron beams for reproducing different colors, here assumed to be green, blue and red aspects of the picture, respectively. At the other end of the tube is a reproducing screen 15 of the fluorescent type with an interposed apertured mask 16. Reproducing screen 15 contains a large number of minute areas in different color phosphors in a desired geometric pattern. The apertures in mask 16 are arranged in a cooperating geometric pattern.

Vertical deflecting coils 17 are arranged about the neck of the tube, along with horizontal deflecting coils 18. The cathode-ray beam 19 issuing from gun 14B is deflected by the deflecting coils about a center of deflection designated 21B. Similarly, cathode-ray beams issuing from guns 14G and 14R are deflected about centers of deflection 21G and 21R. It is of course understood that the actual deflection takes place thru an are rather than at a single point, but the idealized point concept suffices for understanding the present invention.

Referring to Fig. 1(a), a single electron gun 22 is illustrated which replaces the three electron guns of Fig. l and would ordinarily be located on the axis of the tube. By suitable deflecting coils or plates, the cathode-ray beam 23 is caused to assume in succession the three positions designated 24G, 24B and 24R. The successive disseparately generated beams of the tube shown in Fig. 1. In the discussion hereinafter, and in the claims, it will be understood that the term cathode-ray beams refers not only to separately generated beams such as illustrated in Fig. 1, but also to the displaced beams of Fig. 1(a), even though the latter originate from a single gun. It will be understood that the three beams MIG-24R of Fig. 1(a) may be deflected about spaced centers of deflection such as shown at 21G-2IR of Fig. 1.

Fig. 1(b) shows the tube of Fig. 1 in a typical receiver arrangement. Here the composite television signal including color video signals with associated line and field synchronizing signals is picked up by antenna 1 and fed to receiver circuits 2 which may include, for example, R.-F., converter, I.-F. and detector stages. color video signals are amplified in video channel 3 and the difierent color signals fed to the respective electron guns 14G-14R to control the modulation of the elec' tron beams. The video signals ordinarily are fed to either the cathodes or control grids of the electron guns.

The composite signal is also commonly fed to a deflection channel 4 wherein the synchronizing signals are separated from the video and employed to synchronize line and field sawtooth deflection wave generators whose outputs are supplied to deflection coils 18 and 17 respec- The Y tively. Ordinarily the line and field synchronizing pulses are separated and fed to separate line and field deflection. wave generating channels which are here included within the broad phrase deflection channel.

The composite video signal may also include distinctive color synchronizing signals associated with video signals of one color which are utilized to insure that a given color signal will be reproduced in that color.

Details of the utilization of the several synchronizing signals depend on the particular application and are well known in the art. Hence further detail is WIIEWSSQIY here.

Referring now to Fig. 2, points 216, 21B and 21R illustrate the horizontally aligned centers of deflection of the three cathode-ray beams produced as described in connection with either Fig. 1 or Fig. 1(a). The apertured mask and fluorescent screen are shown as fragments rotated about horizontal axes into the plane of the paper for convenience of illustration. The apertured mask 16 is here shown as a mask 16 having elementary vertical slots 25 which are vertically and horizontally aligned. The cathode-ray beams are shown as passing through one slot 25 and impinging on a fluorescent screen 15 composed of narrow vertical strips of green, blue and red phosphors alternating in sequence. In general the width of the strips will be less than the diameter of the scanning beam and the actual dimension will depend upon the amount of detail desired and the diameter of the screen.

Referring now to Fig. 3, an alternative arrangement of the tube of Fig. 1 is depicted in which the three guns 14G, 14B and 14R are arranged at the corners of a triangle, the guns being parallel to each other. An endon view of the guns is shown in Fig. 3(a). In this case the apertured mask 16" has apertures 26 (Fig. 3(b)) arranged so that a trefoil of phosphor dots can be arranged behind each aperture. The phosphor dots are shown in Fig. 3(c) at 27G, 27B, and 27R, respectively. Each trefoil is located behind one of the apertures 26 of Fig. 3(b) and the location of apertures 26 are shown in dotted lines in Fig. 3 (c).

It will be understood that the geometrical arrangement of apertures and phosphors in Figs. 13 is subject to wide variation, and the order of the colors can be selected as desired. The specific arrangements here shown are illustrative only. Generally speaking, the geometry of the systems are such that electrons appearing to pass through one center (such as 21R) strike only the red phosphor elements, those appearing to pass through another center (such as 213) strike only the blue phosphor elements, and those appearing to pass through a third center (such as 216) strike only the green phosphor elements.

Referring now to Fig. 4, the manner in which delay may be employed to register the color images of tubes such as shown in Figs. 1, 1(a) and 2 is illustrated. Points 21G, 21B, and 21R again represent the centers of deflection of the electron beams corresponding to diflerent colors, and are spaced apart in the line-deflection direction. With the three guns of Fig. 1 these electron beams may exist simultaneously or sequentially depending upon the scanning method employed. With the arrangement of Fig. 1(a), they will exist sequentially.

If the cathode-ray beams are acted upon by the same deflecting fields either simultaneously or successively, the lateral displacement of the centers of deflection will re sult in three horizontally-displaced scanning rasters or areas being formed at the fluorescent screen as shown at 31R, 31B and 316 of Fig. 4(b). These rasters will be substantially overlapping and will occupy approximately coextensive areas except for lack of registry. In the ideal case, the three scanning rasters will be identical except for the lateral displacement. The corresponding primary color images will also be laterally displaced as shown by the images of a circle denoted 32R, 32B and 32G.

Fig. 4(c) illustrates obtaining registration by delay of the video waves with respect to the corresponding horizontal deflection waves. Since only relative delay is important, it is assumed that the green video signal is reproduced as in the case of Fig. 4(b). Consequently the circle 33 representing the reproduced circle in all three colors occupies the same position with respect to scanning raster 316 that it did in Fig. 4(b). However, the video signal corresponding to blue has been delayed with respect to its scanning raster 3113 by a fraction of. a line period to superpose the blue image on the green image. The actual amount of delay will of course depend upon'the initial amount of misregistration, the size of the picture and the speed ofhorizontal sweep. The video signal corresponding to red is delayed by approximately twice the amount of the blue signal so as to superpose the red image likewise on the green image, so that all three colors then occupy the position shown by circle 33.

The delay of the video illustrated in Fig. 4(c) is applicable to any type of scanning system, whether simul taneous or sequential. In the case of field and line sequential systems it is also possible to delay the deflection waves rather than the video waves. Referring to Fig. 4(d), the relative phase of'the red video signal and its corresponding deflection Wave are the same as in Fig. 4(b), so that circle 33' occupies the same relative position with respect to its scanning raster 31R. However, scanning raster 31B is delayed with respect to the video by a small fraction of a line period to cause the blue image to coincide with the red image. The actual position of the scanning raster 31B on the face ofthe cathoderay tube will remain the same as in Fig. 4(b) since the magnitude of the deflection current or voltage is'assumed to be the same. However, since the deflection wave has been delayed, thereby changing the relative phase of the video and deflection waves, the blue video signal will occur earlier in the deflection cycle and hence the blue image will be displaced to the left (deflection being assumed to proceed from left to right as in conventional practice). The deflection wave for the green signal is delayed by approximately twice the amount for the blue so that the green image will also coincide with circle 33'.

The time sequence of the video and deflection signals described in connection with Fig. 4 will be more clearly understood by reference to Fig. 6. Here horizontal (line) sawtooth deflection waves 34R, 34B, 34G are shown in Fig. 6(a) for red, blue and green signals. Likewise, red, blue and green video signals 35R, 35B, 35G for a given line are shown in Fig. 6(b).

Fig. 6(0) corresponds to Fig. 4(a), both illustrating effecting registration by delay of the video. In this figure the green video signal 35G has the same phase relative to the deflection wave 346 that it did before. However, the blue video signal 35B has been delayed so that it occurs later relative to scanning wave 34B. Consequently the corresponding line will be shifted to the right in the picture, as was explained in connection with Fig. 4(c). The red video signal wave 35R is delayed by approximately twice the delay of the blue signal, and occurs still later in the course of its deflection wave 34R. Consequently the corresponding red line is shifted still farther to the right in the picture as was explained in Fig. 4(c).

Other lines of the pictures Will be shifted in the manner just described so that the entire area of the red and blue images are shifted into coincidence or registry with the green image.

For field and line sequential systems the deflection and video Waves will occur successively. For dot sequential systems the video waves 35R-35G will be interlaced and deflection waves Mill-34G will be one and the same wave. For simultaneous systems the deflection waves 342-346 will also be one and the same wave. Thus it is apparent that the delay of the video can be employed to obtain registration with any of these systems.

Fig. 6(d) illustrates delay of the deflection waves, and corresponds to Fig. 4(d). Here deflection wave 34R remains unchanged, and occurs in the same relative phase with respect to the video signal 35R that it did originally. Deflection wave 343 is delayed with respect to its original position 34B so that the video signal 35B occurs earlier on the trace. Deflection wave 34G is still further delayed with respect to its original position 34G, so that the corresponding video signal 35G occurs still earlier on the trace. Thus the blue aspect of the image is displaced toward the left of the picture by a given amount, and the green aspect of the image displaced to the left by approximately twice that amount, so that all three color aspects are superposed as shown at 33' in Fig. 4(a').

It will be observed from Fig 6 that the change in relative phase of the video signal waves and the corresponding deflection waves may be accomplished by delaying either the video signal or the deflection wave, the choice depending upon the particular application.

Referring now to Fig. 5, there is depicted the use of delay to register images produced by triangularly arranged electron beams, produced either by three separate guns or by one gun with successive deflection tothree different triangularly arranged positions. In the absence of convergence signals the scanning rasters on the face of the tube will occupy the positionsshown inFig. 5 (b) at 31R, 31B and 316. Respective color aspects of a circular image will occupy the position shown at 32R, 32B and 32G. Since these images also bear a triangular relationship, it is necessary to alter the location of one or more of the images both horizontally and vertically in order to obtain registration. In accordance with the present invention the relative phase of the video and deflection waves is altered by fractions of a line so as to align the three color images horizontally, and delay corresponding to several lines is employed to align the images in the vertical direction.

Fig. 5(c) represents delay of the video signal. Scanning is assumed to proceed from top to bottom and from left to right in the conventional manner. Since circle 326' in Fig. 5(b) is farthest to the right (that is, farthest in the direction of horizontal line scanning), the video signals corresponding to the blue and redaspects are delayed by intervals corresponding to small fractions of the line period so as to align them in the horizontal direction. These delays will bring the centers of the red and blue circles to the vertical line 36. The red and green video signals are also delayed by the necessary number of lines (a fraction of the vertical or field scanning period) to displace their centers in a vertical direction into coincidence with that of the blue circle. The result is shown by the circle 37.

If the displacement of the unregistered images were inverted from that shown in Fig. 5 (b), with circle 32B at the top of the triangle, the same horizontal delays would be employed but in this case only the blue signal would be delayed by the necessary number of line periods to bring it into coincidence with the others. The numerical values of the delays will depend upon the factors discussed in connection with Fig. 4.

Fig. 5 (d) illustrates obtaining registration of the images of Fig. 5(b) by the use of delay in the deflection circuits. Here the deflection wave corresponding to the blue aspect will be delayed by a fraction of a line period to bring blue image into horizontal alignment with the red image, so that the centers will lie on line 38. The deflection wave corresponding to the green image will be delayed approximately twice as much so that its center also will lie on line 38. The deflection wave for the blue signal is additionally delayed by a number of line periods so that all three images are superposed as shown at 37 in Fig. 5(d).

it will be observed that although the use of delay in accordance with the present invention registers the reproduced primary color images, the corresponding scanning rasters do not coincide. Suitable masking may be employed so that the outer portions of the scanning rasters are concealed from view. It will of course be understood that the displacements of the scanning rasters shown in Figs. 4 and 5 have been exaggerated for clarity of illustration and that only a small percentage of the. overall picture area need be masked.

The displacement of the scanning rasters may be re.- duced by an initial inward pointing (toward the center line of the tube) of the cathode-ray beams. For example,

with three guns their axes may converge somewhat in- .stead of being parallel. This also reduces the delay time required for registration. However, the inward pointing ing for the horizontal blanking interval, the delays required calculate to be approximately 0.0131-1 and 0.027H, where H is the horizontal line period. With the presently established FCC color standards of 405 lines and 144 fields per second double-interlaced, H is approximately 34.3 microseconds and the required delays are approximately 0.46 and 0.92 microsecond. For different separations of color centers, different size screens, and different line. periods, appropriate calculations can readily be made.

In the case of vertical displacements, assume that the .vertical spacing of adjacent color centers is 0.2 inch and the other conditions as above. This spacing corresponds to approximately four lines of a single field, with double interlacing, and the delay is accordingly 4H.

Referring now to Fig. 7, a simple circuit is shown for delaying the video signals in tubes of the type employing three separate electron guns. Here 41 represents the .video output tube of the television receiver and 42 represents the DC. reinserter.

These circuits may be conventional and need not be shown in detail. In the output of tube 41 is disposed a delay network comprising sections 42, 43, and 44 with a suitable terminating impedance 45. The delay network is shown as a simple L-C delay line but of course may be elaborated if desired. The design and construction of delay lines is well known in the art and need not be described in detail.

The circuit of Fig. 7 may be used to produce registration as explained in connection with Fig. 4(c). As there explained, the green signal is undelayed and corresponds to the output connection 46 from the input point of the delay line. The blue signal is delayed by a given amount and may be obtained through output connection 47 from an intermediate point of the delay line, it being understood that the delay produced in network 42 is selected to cause the blue image to register with the green image. The red signal is delayed still more and may be obtained from output connection 48. The output signals at terminals 4648 may be applied to the grids or cathodes of the respective electron guns in conventional manner.

The circuit of Fig. 7 may also be designed to produce the delays described in connection with Fig. 5(a). In this event however, since all signals are delayed to some extent, an additional delay section will be interposed between output tube 41 and delay section 42. The smallest delay is that of the blue signal and corresponds to a small fraction of a line AH so that the blue output signal would then be taken from terminal 46. The green signal is delayed by a predetermined number of lines so that filter section 42 would be designed to delay the signal by the given number of lines minus the delay of the previous filter section and would be taken from output terminal 47. The red signal is delayed by the same number of lines plus twice AH. Thus section 43 of the delay line will be designed to produce 2AH delay and the green signal would be taken from terminal 48.

It will be understood that the circuit shown in Fig. 7 is adapted for use with sequential scanning systems wherein separate gating signals are applied to the guns of the cathode-ray tube to turn on the beams in sequence. Thus the video channel provides three signal paths to the tube which are gated to operate successively for different colors. In the case of simultaneous systems the video signals corresponding to difierent colors are commonly separated in the receiver and fed to respective electron guns through separate channels. In this case a delay circuit may be interposed in each channel to produce the required delay as explained in connection with Figs. 4-6.

The delay of the deflection waves can be produced by delaying the synchronizing signals which initiate or control the deflections, or by introducing suitable control signals elsewhere in the deflection channels. Fig. 8 illustrates a suitable circuit for delaying synchronizing signals in a field sequential system. It will be particularly described to effect registration in the manner shown in Fig. 4(d).

Gate generator 51 is'synchronized with the field signals and adapted to generate gates of the type shown in Fig. 8(a). Suitable generators are known in the art and need not be described in detail. A red gate signal has passing pulses 52R occurring with each red field scansion, and cut-oil? portions 53R therebetween. Similar passing and cut-off pulses are generated for the blue and green gates. Horizontal synchronizing pulses are applied at 54 to a delay line generally designated as 55. Gated electron tubes 56R, 56B and 566 have their respective control grids connected to spaced points on the delay line. The gating signals from generator 51 are also applied to these tubes. Any suitable amplifier tubes may be employed and the gating signals may be applied thereto in any convenient manner known in the art. It is usually desirable to apply the gating signals to other than the control grids and in the case of triodes they may conveniently be applied to the cathodes. If pentodes are used the gating signals may be applied to the cathodes, screen grids or suppressor grids. The polarity of the gating signals depend upon the electrodes to which they are applied as will be understood.

As indicated in the discussion of Fig. 4(d), the deflection Waves corresponding to the red signal are undelayed. Accordingly the control grid of tube 56R is connected to the input of the delay line and horizontal synchronizing pulses appearing in the common output line 57 will be u ndelayed. During the red field scansion tube 56R is on, and tubes 56B and 566 are off. During the blue field scansion, tube 56B is on and the other tubes ofi. Consequently the horizontal synchronizing signals corresponding to the blue scansions will be delayed by the first portion of delay line 55 by the amount necessary to register the blue image with the red image. As explained before this is a small fraction of a line period in the embodiment shown in Fig. 4(d). During the green field scansion, tube 566 is on and the others 0E, so that the horizontal synchronizing signals corresponding to the green scansion are delayed by both sections of delay line 55. Variable taps on the delay line may be employed for precise adjustment of registration if desired. The output from line 57 is fed to the line deflection wave generator to control the synchronization thereof.

The arrangement of Fig. 8 may readily be adapted to scanning methods of the line sequential type by gating the tubes 56R-56G at line frequency rather than at field frequency.

In the arrangement depicted in Fig. 5 (d), delay of the deflection waves in both horizontal and vertical channels is required. In this event, the circuit of Fig. 8 may be employed to delay the horizontal synchronizing signals in the manner just described. A similar circuit may be arranged in the vertical synchronizing channel to delay the vertical signals by the necessary amounts.

If desired, instead of employing delay lines, other devices such as multivibrators may be used to produce delayed synchronizing pulses. This may be particularly advantageous where delay of the vertical synchronizing signals is required.

It is also possible to use the circuit of Fig. 8 to delay the video signal by the required amounts, the video being supplied to input 54. Such an arrangement is advantageous in a sequential system employing a single gun splitter or polarity-inverter.

. 9 tricolor tube, since gating is associated with the delay circuit and the common output lead 57 can be connected to the single electron gun to provide sequential video signals with each color properly delayed. For a three-gun tube, tubes 56R56G can be provided with separate output circuits leading to respective guns of the tricolor tube. In such case the gating in the delay circuit insures supplying each gun with the proper color video signal without gating at the guns themselves. In either of these cases it will be apparent that three signal paths are provided in the video channel which are gated to operate successively for video signals of different color respectively.

With spaced centers of deflection of the electron beams in a single cathode-ray tube, and common focusing and deflection coils or electrodes, the scanning rasters corresponding to the several centers of deflection may not be exactly the same. With the centers of deflection arranged along a single line, as described in connection with Figs. 1 and 1(a), the scanning raster corresponding to the middle center of deflection can be made approximately rectangular. This has been assumed to be the blue scanning raster and is shown at 61B in Fig. 9(a). The sides of the other two scanning rasters are often distorted in the manner shown by the scanning rasters 616 and 61R. It will be noted that the distortion of the green raster is the reverse of that of the red raster since the two guns are on opposite sides of the middle gun.

The picture of a square object will yield color images 62R, 62B and 62G wherein images 62R and 628 have the same type of distortion as that of the scanning rasters, in addition to the misregistration previously discussed.

Considering the red image 62R, if the upper and lower lines are moved to the left with respect to the middle line of the image, the distortion can be corrected. This can be accomplished by delaying the red deflection waves for the top and bottom of the picture more than for the center of the picture. This will cause top and bottom lines to be reproduced earlier in the respective horizontal deflection cycles and hence will move them to the left of the picture. The result will be a straightening of the lateral sides of the red image as shown at 62R in Fig. 9(b). Similarly, the sides of the green image 62G can be straightened by delaying the deflection waves for the middle of the picture more than for the top and bottom of the picture. The result is shown at 626'. Then the images can be registered by the use of delay in the manner described in connection with Fig. 4(d).

In the case most often met with in practice, the distortion of the sides of the scanning pattern and of reproduced images is generally parabolic in shape. Consequently a variable delay of the red and green synchronizing pulses which follows the parabolic law will suifice. In the usual television receiver employing a self-biased vertical deflection output tube, a wave exists at the oathode which is' roughly parabolic in shape. This has been found to be quite satisfactory to correct the type of distortion illustrated in Fig. 9. In case other types of distortion are present, suitable waves may be found in the television receiver or may be specially generated for the purposes of correction.

Referring now to Fig. 10, a correcting waveform 65, here assumed to be parabolic, is applied at 66 to a gain control 67. This wave is amplified by tubes 68 and 69 Whose circuit connections may follow conventional practice and need not be described in detail. The parabolic waveform is depicted at several points in the circuit to indicate polarity. Tube 71 is supplied with the amplified parabolic wave and is connected as a conventional phase- The parabolic wave taken from the cathode through lead 72 has the original polarity as shown at 65'. The wave taken from the anode through lead 73 is of similar shape but inverted as shown at 655.

Control tubes 81R, 81B and 816 are supplied. with positive grid bias from B+ through voltage dividers comprising resistors 83R, 84R, 83B, 84B, 836, 84G, respectively. Series resistors 85R, 856 are connected in the grid circuits of tubes 81R and 81G to permit the application of the parabolic control signals to their control grids through coupling capacitors 86R and 86G to which leads 73 and 72 are respectively connected. The anodes are connected to a common B+ line 82. No series grid resistor need be provided for tube 81B since its potential is not varied in the specific embodiment illustrated;

Output voltages are taken from the cathode circuits of respective tubes across cathode resistors 87R, 87B and 87G, respectively. Tubes SIR-81G thus function as cathode followers and, since the respective control grids are positively biased, the cathode potentials are positive to ground and yield output signals having a positiveD.-C. component. These output signals are connected to the screen grids of pentode tubes 92R, 92B and 926 through respective leads 83R, 88B and 886. The latter tubes are gated in sequence by suitable negative gating signals 93R, 93B and 93G applied to the suppressor grids thereof. The cathodes are grounded as shown, and the anodes connected to a common output circuit 94 having a common anode load 90 leading to B+.

Horizontal synchronizing signals of negative polarity are supplied to the control grid of tube 92R through a coupling capacitor 9 5 and resistor 96. The signals are likewise applied to the control grid of tube 92B through an integrating circuit comprising resistor WB, variabie resistor 93B and capacitor 993. The signals are applied to the control grid of tube 926 through a similar integrating circuit comprising elements 97G, 98G and 99G.

Overall operation of the circuit of Fig. 10 will now be described.

The parabolic wave 65" of positive polarity is applied to the grid of tube 81R and a wave of similar polarity (with a positive D.-C. component) is supplied from the cathode of that tube to the screen grid of tube 92R. Hence, the amplification of tube 92R at the middle of the vertical sweep is greater than that at the beginning and end of the vertical sweep. In consequence the input horizontal synchronizing pulses for the red field scansion are amplified to a greater extent for the middle lines than for the top and bottom lines.

Fig. 10(a) shows at 101 an applied horizontal synchronizing pulse on an enlarged and somewhat exaggerated scale. Due to bandwidth limitations in conventional television receivers these pulses are not strictly rectangular but have curved leading and trailing edges. If the slope of the leading edge is not suflicient for the purpose, it can readily be made so by an integrating circuit as will be described in connection with tubes 92B and 92G.

Fig. 10(1)) represents the output synchronizing pulse 101 of tube 92R under conditions of relatively low amplification such as occurs for the top and bottom lines of the picture. The synchronization of the horizontal deflection wave generator ordinarily depends upon a predetermined difference in potential Vs, such as illustrated by the line 102. The triggering of a blocking oscillator by a synchronizing signal applied to its grid circuit is an example and will here be assumed.

Fig. 10(c) illustrates an output pulse of tube 92R with greater amplification due to a higher screen voltage such as would occur during the middle lines of the picture. Line 103 denotes the voltage Vs required to synchronize the horizontal oscillator and is the same as inFig. 10( b).

Due to the greater amplification, the time n required for the leading edge of the pulse to reach the potential Vs in Fig. 10(0) is less than time is in Fig. 10(1)). Consequently the synchronization of the line deflection wave generator is delayed for the top and bottom b lines of the picture with respect to the middle lines. The delay follows the parabolic law approximately and is in the proper direction "to correct for the distortion of the red image as illustrated in Figs. 9(a) and 9(b).

The invert ed parabolic waveform 65 is supplied through lead 72to control tube 816, and thence to the screen grid of tube 926. The amplification of tube 926 is thus greater at the top and bottom of the picture than at the middle. This results in delaying the horizontal synchronizing pulses for the middle of the picture more than for the top and bottom, which is in the proper direction to correct for the distortion of the green image as shown in Figs. 9(a) and 9(1)).

The operation of the circuit of Fig. 10 as explained thus far would result in three substantially undistorted overlapping color images as shown in Fig. 9 (b), but the images are still not in registry. The necessary delay of the horizontal synchronizing pulses corresponding to the blue image is accomplished withthe aid of the integrating circuit in the input to tube 9213. The values of elements 9713-9913 are selected so that the leading edge of the synchronizing pulse supplied to 923 has a greater rise time than that for tube 92R. This is shown by leading edge 104 in Fig. 10(11). An output pulse of similar shape but inverted polarity will be produced by tube 92B and its leading edge is represented at 164 in Fig. 1012. It will be understood that the amplitude of the pulse need not be the same as that appearing in the output of tube 92R under minimum amplification conditions, but may be selected as desired.

It will be observed that due to the greater rise time of leading edge 104, the time ta taken to reach the synchronizing potential V5 is longer than tz for the red signal. By appropriate selection of the amplification of tube 923 and adjustment of the grid circuit by variable resistor 983, a delay of the synchronizing pulses for the blue signal suflicient to register the blue image with the red image may be obtained. Since the blue image was assumed to be initially undistorted, no variable screen voltage need be applied to this stage.

The integrating circuit 97G99G at the input to tube 926 may be selected to give a still greater rise time in the leading edge of the horizontal synchronizing pulses applied to that tube, as shown at 105 in Fig. 10(a). The corresponding output pulse will have a leading edge such as represented at 105 in Fig 10(1)), and the corresponding time for the leading edge to reach the level V5 is it. Accordingly, the synchronizing pulses for the green signal are delayed more than for the blue signals and brings the green image into registry with the red and blue images.

The correction of distortion in the red image may involve a slight delay of all portions of the red image, the minimum delay at the center of the picture being represented as n in Fig. 10(c). With suflicient amplification and sufficiently low value of Vs this time interval may be t negligible. If not negligible, it can of course be taken into account by slightly increasing the delay of the blue and red synchronizing pulses. Furthermore, even though the delay of the green synchronizing pulses is varied from top to bottom of the picture, the average delay produced by the effect of the input integrating circuit may be adjusted by resistor 98G so that overall superposition is obtained.

Fig. 10 has been specifically described in connection with a field sequential scanning procedure. It may however be readily adapted to line sequential systems, as will be understood by those skilled in the art. In this case the tubes 921 -92G will be gated at line frequency rather than at field frequency.

The delay of the deflection waves has been described in connection with Figs. 8 and 10 as being obtained by a delay of the synchronizing pulses. In many cases it is possible to apply control voltages elsewhere in the deflection signal generator so as to change the phase of the deflection waves for different color signals, the choice depending upon the judgment of the designer.

Fig. 11 is a block diagram illustrating the general phase control of deflection waves. Here a color gate generator 111 is synchronized with the color signals and generates red, blue and green gates. In field sequential systems the gates may be at field frequency and in line sequential systems at line frequency. These gates are applied to red, blue and green phase control stages 112R, 112B and 112G. These stages may be designed in any desired manner to yield output control waves which are different for the diiferent color signals. The outputs may then be combined and fed to a suitable point in the horizontal deflection wave generator to control the phase of the deflection waves with respect to the initial horizontal synchronizing signals. Where variable delay for a given color image is desired, dynamic control waves may be applied through connection 11 i to the phase control tubes 112R112B in any suitable manner.

In the foregoing the invention has been described in connection with a number of specific embodiments. Many elaborations and embodiments may be devised within the spirit and scope of the invention as will be understood by those skilled in the art. Also in a given application only portions of the invention may be used and other portions omitted, depending on the particular application.

I claim:

1. In a color television receiver employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, a deflection channel for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a phase control circuit associated wtih one of said channels for changing the phase of waves therein corresponding to one color with respect to waves corresponding to another color, whereby the relative phase of video and deflection waves corresponding to said one color may be changed with respect to similar waves corresponding to said other color to shift the reproduced images of respective color toward registry.

2. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, at deflection channel for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and delay circuit means in one of said channels for delaying waves therein corresponding to one color with respect to waves corresponding to another color to thereby shift the reproduced images of respective color toward registry.

3. In a color television receiver employing a multi-color tube in which a plurality of cathode-ray beams are deflected horizontally and vertically at spaced centers of deflection by common deflection means and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray'beams with respective color video signal waves representing diflerent primary colors, at deflection channel for generating line and field deflection waves synchronized with said video waves and connected to said common deflection means to deflect said beams over approximately coextensive scanning areas of said reproducing screen, and delay circuit means in one of said channels for delaying waves therein corresponding to one color With respect to similar waves corresponding to an- 13 other color by predetermined amounts to shift the reproduced images of respective colors toward registry.

4. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected in said tube for modulating said cathode-ray beams with respective color video signal waves representing diflerent primary colors, a deflection channel for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scannin areas of said reproducing screen, and delay circuit means in one of said channels for changing the relative phase of video and deflection waves corresponding to one color with respect to the relative phase of said waves corresponding to another color to shift the reproduced images of respective colors toward registry.

5. In a color television receiver employing a multi-color tube in which a plurality of cathode-ray beams are deflected horizontally and vertically at spaced centers of deflection by common deflection means and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a. color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing diflerent primary colors, a deflection channel for generating line and field deflection waves synchronized with said video waves and connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and delay circuit means in one of said channels for changing the relative phase of said video and line deflection waves corresponding to one color with respect to the relative phase of said waves corresponding to another color to shift the reproduced lines of respective color images toward horizontal registry.

6. In a color television receiver for multi-color video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproduction screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signals of different color, a deflection channel supplied with said synchronizing signals for generating deflection waves synchronized with said video signals and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a delay circuit in one of said channels supplied with signals therein corresponding to one color to delay said signals with respect to similar signals corresponding to another color, whereby the relative phase of video signal and deflection waves corresponding to one color may be altered with respect to another color to shift the reproduced images of respective color toward registry.

7. In a color television receiver for multi-color video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by line and field deflection means and impinge on a reproduction screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing diflferent primary colors, a deflection channel supplied With said synchronizing signals for generating deflection waves synchronized with said video signals and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a delay line in one of said channels for 14 delaying waves in said channel corresponding to one color by a small fraction of a line period with respect to similar waves corresponding to another color, whereby the relative phase of video and deflection waves corresponding to said one color may be changed with respect to similar waves corresponding to said other color to shift the reproduced images of respective color toward registry.

8. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in' which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing diflerent primary colors, 2. deflection channel supplied with said synchronizing signals for generating deflection Waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, a delay circuit in one of said channels for delaying waves therein, and gating means for said delay circuit synchronized with waves of one color whereby said waves are delayed with respect to corresponding waves of another color, whereby the relative phase of video and deflection waves corresponding to said one color may be changed with respect to similar Waves corresponding to said other color to shift the reproduced images of respective color toward registry.

9. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected by common line and field deflection means about centers of deflection having spacing therebetween in line and field scanning directions and impinge on a reproducing, screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different primary colors, a deflection channel for generating line and field deflection waves synchronized with said video waves and connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, delay circuit means in one of said channels for changing the relative phase of video and line deflection waves corresponding to one color by a small fraction of a line period with respect to the relative phase of waves corresponding to another color to shift the reproduced images of respective color toward horizontal registry, and delay circuit means in one of said channels for changing the relative phase or" video and field deflection waves corresponding to one color by a number of line periods with respect to Waves corresponding to another color to shift the reproduced images of respective color toward vertical registry.

10. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, a deflection channel for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a de lay circuit associated with said video channel for delaying video waves therein corresponding to one color with respect to video waves corresponding to another color to thereby shift the reproduced images of respective colors toward registry.

11. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel having a plurality of output circuits connected to said tube for modulating said plurality of cathode-ray beams with video signal waves of respectively different color, a deflection channel for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a delay circuit in at least one of said output circuits to delay the corresponding color video signal therein by a predetermined amount with respect to another color video signal to thereby shift the reproduced images of respective color toward registry.

12. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected horizontally and vertically at spaced centers of deflection by common line and field deflection means and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, a deflection channel for generating line and field deflection waves synchronized with said video waves and connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, and a delay circuit in the path of the video signal of one color predetermined to delay said signal by a small fraction of a line period with respect to the video signal of another color to thereby shift the reproduced images of respective colors toward registry.

13. In a color television receiver employing a multicolor tube in which a plurality of cathode-ray beams are deflected horizontally and vertically at spaced centers of deflection by common line and field deflection means and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different primary colors, a deflection channel for generating line and field deflection waves synchronized with said video waves and connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, and a delay circuit in the path of the video signal of one color predetermined to change the relative phase of said video signal and the corresponding line deflection wave by a small fraction of a line period with respect to the relative phase of video and line deflection waves corresponding to another color to thereby shift the reproduced images of respective color toward registry.

14. In a color television receiver for sequential militicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different primary colors, said video channel having a plurality of signal paths gated to operate successively for video signals of different color respectively, a deflection channel supplied with said synchronizing signals for generating deflection waves synchronized with said video waves and connected to said deflecting means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a delay circuit in one of said signal paths predetermined to delay video signals of corresponding color with respect to video sigid nals of different color in another of said signal paths to thereby shift the reproduced images of respective color toward registry.

15. In a color television receiver for tri-color sequential video signals employing a tri-color tube in which three cathode ray beams are deflected by common line and field deflection means about centers of deflection having spacing therebetween in the line-deflection direction and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a deflection channel for generating line and field deflection waves synchronized with said video signals and connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, a color video signal channel supplied with said tri-color video signals and having a video delay line associated therewith, connections from different points on said delay line to said tube to modulate said cathode-ray beams with respective color video signals of different delay, said connections being predetermined to delay the reproduction of at least two colors by small fractions of a line period to thereby shift the reproduced images of said two colors into horizontal registry with the third color image.

16. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, a deflection channel supplied with said synchronizing signals for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and delay circuit means associated with said deflection channel for delaying deflection waves corresponding to one color with respect to deflection waves corresponding to another color to thereby shift the reproduced images of respective colors toward registry.

17. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, a deflection channel supplied with said synchronizing signals for generating deflection waves synchronized with said video waves and connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, and a phase control circuit associated with said deflection channel synchronized with said video signals to alter the phase of deflection Waves corresponding to one color with respect to deflection waves corresponding to another color to thereby shift the reproduced images of respective color toward registry.

18. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different colors, deflection wave generating means connected to said deflection means to deflect said beams 17 over substantially overlapping scanning areas of said reproducing sc'r'een, delay circuit means supplied with said synchronizing signals for delaying synchronizing signals corresponding to one color with respect to synchronizing signals corresponding to another color, and connections from said delay circuit means to synchronize said deflection wave generating means, whereby the reproduced images of said colors may be shifted toward registry.

19. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respectivecolor video signal waves representing different primary colors, deflection wave generating means connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, delay circuit means supplied with said synchronizing signals for delaying the synchronizing signals corresponding to one color relative to the respective color video signals to change the relative phase thereof with respect to the relative phase of synchronzing and video signals of another-color, and connections supplying the delayed synchronizing signals to said'deflection wave generating means to thereby shift the reproduced images of said colors toward registry.

20. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different primary colors, deflection wave generating means connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, a delay line supplied with said synchronizing signals, and connections to said deflection wave generating means from different points on said delay line yielding synchronizing signals of diflerent delay relative to the corresponding color video signals, whereby the reproduced images of said colors may be shifted toward registry.

21. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signal waves representing different primary colors, deflection wave generating means connected to said deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, a delay line supplied with said synchronizing signals, a plurality of gated tubes synchronized with said color video signals and connected to respectively different points on said delay line to yield control synchronizing signals whose phase with respective color video signals is different for different colors, and connections supplying said control synchronizing signals to said deflection wave generating means to control the synchronization thereof and thereby shift the reproduced images of said different colors toward registry.

22. In a color television receiver for sequential multicolor video signals having line and field synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deiflected by common line and field deflection means about respective centers of deflection having spacing therebetween in the line-deflection direction and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signals representing different colors, line and field deflection wave generators connected to respective deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, a delay line supplied with said line synchroniz ing signals, a plurality of gated electronic tubes synchronized with said color video signals having a common output circuit and respective input circuits connected to different points on said delay line to yield output control synchronizing signals whose phase with respective color video signals is different for different colors, and a connection from said output circuit to said line deflection generator to control synchronization thereof and thereby shift the reproduced images of said different colors into horizontal registry.

23. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at spaced centers of deflection by common deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video sig nal waves representing different primary colors, deflection wave generating means connected to said common deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, a plurality of electronic tubes supplied with synchronizing pulses and gated to operate successively during the reproduction of respective successively different colors, connections supplying the output synchronizing pulses of said tubes to said deflection wave generating means to control the synchronization thereof, and a circuit associated with at least one of said tubes to increase the rise time of the output pulses from said tube whereby the corresponding deflection waves are delayed to shift reproduced images of corresponding color toward registry with images of another color.

24. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at centers of deflection having lateral spacing therebetween by common vertical and horizontal deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams in sequence with color video signal waves of respectively different primary color, vertical and horizontal deflection channels for generating respective field and line deflection waves synchronized by said synchronizing signals and connected to'respective deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen, the sides of the scanning area corresponding to one color being distorted with respect to another, a phase control circuit connected in said horizontal deflection channel operable to change the phase of deflection waves corresponding to one color relative to the video signal of like color, a source of a control wave whose magnitude varies during a fieldscanning period, and connections supplying said control wave to said phase control circuit to change the relative phase of the video signal and deflection waves of one color by an amount varying over a field scansion to thereby at least partially correct distortion of images in said distorted scanning area.

25. In a color television receiver for sequential multicolor video signals having synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected at centers of deflection having lateral spacing therebetween by common vertical and horizontal deflection means and impinge on a reproducing screen to yield respective color images, apparatus which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams in sequence with color video signal Waves of respectively different primary color, vertical and horizontal deflection channels for generating respective field and line deflection waves synchronized by said synchronizing signals and connected to respective deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, the sides of the scanning area corresponding to one color being distorted with respect to another, a phase control circuit connected in said horizontal deflection channel operable to change the relative phase of the video sig nal and deflection waves corresponding to one color with respect to the relative phase of said waves corresponding to another color to horizontally register images of the respective colors, a source of a control wave whose magnitude varies during a field-scanning period, and connections supplying said control Wave to said phase control circuit to change the relative phase of the video signal .and deflection waves of one color by an amount varying over a field scansion to thereby atleast partially correct distortion of images in said distorted scanning area.

26. In a color television receiver for sequential multicolor video signals having line and field synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected by common line and field deflection means about respective centers of deflection having spacing therebetween in the line-deflection direction and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signals representing diflerent colors, line and field deflection wave generators connected to respective deflection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, the sides of the scanning area corresponding to one color being distorted with respect to another, a plurality of electronic tubes supplied with line synchronizing pulses of diflerent rise times respectively and gated to operate successively during the reproduction of respective successively difl'erent colors, at least one of saidtubes being of variable gain, a source of a control wave whose magnitude varies over a field-scanning period and connections supplying said control Wave to 20.. said one tube to control the gain thereof, and connections supplying the outputs of said tubes to the line. deflection wave generator to thereby delay the deflection waves corresponding to one color with respect to another and to vary the delay of deflection waves corresponding to one color over a field-scanning period.

27. In a color television receiver for sequential multicolor video signals having line and field synchronizing signals associated therewith and employing a multi-color tube in which a plurality of cathode-ray beams are deflected by common line and field deflection means about respective centers of deflection having spacing therebetween in the line-deflection direction and impinge on a reproducing screen to yield respective color images, apparatus for registering said images which comprises a color video signal channel connected to said tube for modulating said cathode-ray beams with respective color video signals representing different colors, line and field deflection Wave generators connected to respective defiection means to deflect said beams over substantially overlapping scanning areas of said reproducing screen which are relatively displaced in the line-scanning direction, the sides of the scanning area corresponding to one color being distorted With'respect to another, a plurality of electronic tubes having respective input circuits supplied with line synchronizing pulses and a common output circuit connected to said line-deflection wave generator to control the synchronization thereof, said tubes being gated to operate successively during the reproduction of successively different colors and at least one tube being of variable gain, an integrating circuit in the input circuit of at least one of said tubes to increase the rise time of the synchronizing pulses applied thereto and thereby delay the deflection Waves corresponding to at least one color and shift the corresponding reproduced color image toward registry with another, a source of a control wave whose magnitude varies over a field-scanning period and connections supplying said control wave to said variable gain tube to vary the gain thereof and thereby vary the delay of the deflection waves corresponding to one color to at least partially correct distortion of images produced by said distorted scanning area.

Images