US3430099A - Simplified deflection system for plural in-line beam cathode ray tube - Google Patents

Description

Feb. 25, 1969 SIMPLIFIED Filed Aug. 23, 1966 R. B. ASHLEY 3,430,099

DEFLECTION SYSTEM FOR PLURAL IN-LINE BEAM CATHODE RAY TUBE Sheet VERTICAL OUTPUT 9 5 g a/:3 l:

HORIZONTAL OUTPUT INVENTOR ROBERT B. ASHLEY,

BY M5144 HIS ATTQRNEY.

Feb. 25, 1969 R. B. ASHLEY 3,430,099

SIMPLIFIED DEFLECTION SYSTEM FOR PLURAL IN-LINE BEAM CATHQDE RAY TUBE Filed Aug. 23, 1966 Sheet Z of 8 45 45 FIG.3 4s 45 45 I I I I I I I I I l I l I I I I I I I I I I \I v I, II l \I, I I I I I 1 l I I I 1 I A II III I INVENTOR'- ROBERT B. ASHLEY,

HIS ATTORNEY.

Feb. 25, 1969 R. 5. ASHLEY 3,430,099

SIMPLIFIED DEFLECTION SYSTEM FOR PLURAL IN-LINE BEAM CATHODE RAY TUBE Filed Aug. 25, 1966 Sheet 3 Of 8 INVENTORI EL yaw B. ASHLEY. BY

HIS ATTORNEY.

Feb. 25, 1969 SIMPLIFIED DEFLECT ION SYSTEM FOR PLURAL IN-LINE Filed Aug. 23, 1966 R B. ASH LEY 3,430,099

BEAM CATHODE RAY TUBE Sheet 4 of 8 KEY FIRST WINDING (I24) SECOND WINDING (I28) THIRD WINDING (I32 FOURTH WINDING(|36I INVENTORZ ROBERT B. ASHLEY,

BYmmfi HIS ATTORNEY.

Feb. 25, 1969 SIMPLIFIED DEFLEcT'Io Filed Aug. 225, 1966 R B. ASHLEY BEAM CATHODE RAY TUBE VERTICAL TURNS vs N SYSTEM FOR PLURAL IN-LINE ofB 4 Sheet 5 FIG.7

I I 1 I O O O O O N w an r swam d0 aaawnn lVlOl INVENTORI ROBERT B.

HIS ATTORNEY.

R. 8. ASHLEY Feb. 25. 1969 3,430,099 SIMPLIFIED DEFLECTION SYSTEM FOR PLURAL IN-LINE v BEAM CATHODE RAY TUBE Sheet Filed Aug. 23, 1966 A m om Om Oh 0m On swam =10 uaawnu "W101.

wdE

INVENTOR ROBERT 8. ASHLEY.

BY HIS ATTORNEY.

Feb. 25, 1969 9 8. ASHLEY 3,430,099

SIMPLIFIED DEFLECT ION SYSTEM FOR PLURAL IN-LINE 9 BEAM CATHODE RAY TUBE Filed Aug. 23, 1966 Sheet 7 of s o .FIGJO ROBERT 8. ASHLEY BY 9140i HIS AT'TORNEY.

Feb. 25, 1969 R. 8. ASHLEY I 3,430,099

SIMPLIFIED DEFLECTION SYSTEM FOR PLURAL IN-LINE BEAM CATHODE RAY TUBE Filed Aug. 23, 1966 Sheet 8 Of 8 HIGH VOLTAGE lNVENTOR:

ROBERT E. ASHLEY,

ms ATTORNEY.

United States Patent 3,430,099 SIMPLIFIED DEFLECTION SYSTEM FOR PLURAL lN-LINE BEAM CATHODE RAY TUBE Robert B. Ashley, Chesapeake, Va., assignor to General Electric Company, a corporation of New York Filed Aug. 23, 1966, Ser. No. 574,411

U.S. Cl. 315-27 13 Claims Int. Cl. H013 29/72 ABSTRACT OF THE DISCLOSURE In a plural, in-line beam color cathode ray tube, convergence of the beams is achieved by means of optimally non-uniform fields in the deflection yoke which produces parallel-sided beam rasters. For this purpose, toroidal horizontal and vertical deflection windings are used, the turns distribution being different as between the two windings, the vertical winding having a greater number of turns than the horizontal. Any resulting difference in raster sizes is compensated for by size correction windings responsive to the linear deflection currents of the deflection yoke to provide linearly varying predeflection fields operative on the outermost beams of the illustrated three beam arrangement.

The present invention relates to plural beam cathode ray tubes of the type suitable for displaying a color television presentation and more specifically to a simplified deflection system for such a plural beam cathode ray tube.

Plural beam cathode ray tubes employing three electron guns in a triad arrangement are conventionally employed in the prior art. Plural beam cathode ray tubes are also known wherein three in-line electron guns are employed in contrast to the conventional triad arrangement. Either of these electron gun arrangements can be employed in a conventional aperture mask tube or in a tube of the post acceleration type.

In the past, the deflection systems for such cathode ray tubes whereby deflection and convergence of the plural beams is achieved have been extremely complicated and expensive. Thus, the almost universal approach has been to employ an aperture mask tube having a triad arrangement of electron guns in conjunction with a massive deflection yoke, the yoke utilizing a large amount of copper wire wound in a cosine distribution to achieve as nearly as possible a linear deflection field within the yoke. However, such a linear deflection field inherently produces parabolic errors and misconvergence of the resultant rasters. Accordingly, it has been conventional to employ pre-deflection to achieve the necessary dynamic convergence of the plural electron beams. Such dynamic convergence requires the generation of complex parabolic correction signals of proper amplitude and phase relative to the sweep currents in the deflection yoke. The circuitry for generating such complex parabolic convergence signals is extremely complex and expensive. v

It is also known that the convergence problems associated with such a plural beam cathode ray tube can be simplified somewhat through the use of a deflection yoke producing a non-uniform deflection field. Thus in U.S. Patent 2,925,542Gethmann, issued Feb. 16, 1960 and assigned to the assignee of the present invention, there is disclosed a deflection yoke for providing deflection of plural in-line electron beams, the yoke including horizontal and vertical windings having identical winding distributions.

Through the use of the distribution disclosed by the Gethmann patent, deflection of in-line plural electron beams was simplified since dynamic convergence was not required in the direction normal to the planes in which the electron guns lie.

However, even with the improvements of the Gethmann patent dynamic convergence was necessary in the direction parallel to the plane in which the guns lie. Thus, even though the Gethmann patent represented a significant improvement, it was necessary to employ dynamic convergence in at least one direction thus adding a great deal of expense and complexity to the television receiver.

The present invention presents a simplified deflection system which completely eliminates the necessity for complex dynamic convergence signals.

Accordingly, an object of the invention is to provide a simplified deflection system for a plural in-line beam cathode ray tube.

A further object is to provide a simplified deflection system for a plural in-line :beam cathode ray tube which is less complex and expensive than prior art systems.

Yet another object is to provide a simplified deflection system for a plural in-line beam cathode ray tube which completely eliminates the necessity for complex dynamic convergence signals.

These and other objects are achieved in one embodiment of the invention through the use of a deflection yoke which produces an optimally non-uniform field by the utilization of diflerent winding distributions for the horizontal and vertical windings. Through the use of such a deflecton yoke three rasters are produced from which parabolic errors are eliminated, the rasters only requiring correction as to size. The size correction is easily achieved by passing the sawtooth deflection currents through a predeflection system. In this manner, substantial registry of the three rasters is achieved without the necessity for complex dynamic convergence waveforms.

The novel and distinctive features of the invention are set forth in the appended claims. The invention itself together with further objects and advantages thereof may best be understood by reference to the accompanying drawings in which:

FIGURE 1 is a top view of a plural in-line beam cathode ray tube utilizing the simplified deflection system of the invention.

FIGURE 2 is a side view of the plural in-line beam cathode ray tube depicted in FIGURE 1,

FIGURE 3 depicts the parabolic errors inherent in the prior art deflection systems,

FIGURE 4 is a schematic representation of a horizontal deflection winding in accordance with the invention,

FIGURE 5 is a schematic representation of a vertical deflection winding in accordance with the invention,

FIGURE 6 depicts a preferred embodiment of the win-ding distributions shown in FIGURES 4 and 5,

FIGURE 7 is a graphical representation of the vertical winding distribution shown in FIGURE 6,

FIGURE 8 is a graphical representation of the horizontal winding distribution shown in FIGURE 6,

FIGURE 9 depicts the raster size errors produced by the deflection yoke of FIGURE 6,

FIGURE 10 is a view taken along the line AA of FIGURE 1 depicting the pre-deflection system for correcting the vertical size errors shown in FIGURE 9,

FIGURE 11 is a view taken along the line B--B of FIGURE 1 depicting the pre-deflection system for correcting the horizontal size error shown in FIGURE 9, and

FIGURE 12 is a schematic diagram of the deflection circuitry of a color television receiver employing the simplified deflection system of the invention.

Referring to FIGURES 1 and 2, there is depicted in simplified form a top view of a plural in-line beam cathode ray tube shown generally at 1 employing the simplified deflection system of the invention. The cathode ray tube 1 includes a neck portion 3, a funnel portion 5 and a faceplate 7 upon the interior face of which are deposited phosphor dots (not shown) for the production of a color television image. A plurality of electron guns 9, 11 and 13 are positioned in the neck portion 3, the electron guns 9, 11 and 13 producing electron beams 15, 17 and 19 respectively. As depicted, the electron guns 9, 11 and 13 are aligned in a horizontal plane with the axis of the guns 9 and 13 positioned at a slight angle relative to the axis of the gun 11 such that the electron beams 15, 17 and 19 are statically converged at approximately the center of the faceplate 7. By way of example, the electron guns 9, 11 and 13 may be utilized to respectively excite blue, green and red light producing phosphors positioned on the faceplate 7 and for purposes of clarity will be hereafter referred to as the blue, green, and red electron guns respectively. For clarity the electron beams 15, 17 and 19 are shown as dotted, dashed and dash-dot lines respectively.

The electron beams 15, 17, and 19 are directed through suitable apertures in an aperture mask 21 in accordance with known techniques to selectively excite the blue, green and red light producing phosphor dots on the faceplate 7. The aperture mask 21 may be of the type disclosed and claimed in the co-pending application of W. D. Rublack, Ser. No. 573,604 filed Aug. 19, 1966.

In accordance with the invention, the electron beams 15, 17 and 19 are deflected by a deflection yoke shown generally at 23 to produce three superimposed rasters of different colors on the faceplate 7.

The yoke 23 is provided with horizontal and vertical deflection windings having distributions such that an optimally non-uniform magnetic field is produced within the yoke whereby the parabolic errors associated with the use of a uniform field yoke are eliminated. Through the use of the yoke 23 of the invention, complex dynamic convergence signals are no longer required, simple size correction of the rasters produced by the blue electron gun 9 and the red electron gun 13 being all that is necessary. In this regard a vertical static convergence and size correction assembly shown generally at 25 including a vertical size correction winding is positioned around the neck 3 of the cathode ray tube 1 intermediate the electron guns 9, 11 and 13 and the deflection yoke 23. Similarly, a horizontal static convergence and size correction assembly shown generally at 27 including a horizontal size correction winding is positioned around the neck 3 of the cathode ray tube 1 intermediate the assembly 25 and the deflection yoke 23.

In accordance with the invention as shown in FIGURE 1 the size correction winding of the vertical static convergence and size correction assembly is serially connected to the vertical deflection winding of the yoke 23 via a line 29, the vertical winding of the deflection yoke 23 being itself connected via a line 31 to the vertical output stage 33. In this manner a sawtooth deflection current flows between the vertical output stage and ground through the vertical winding of the deflection yoke 23 and the vertical size correction winding of the vertical static convergence and size correction assembly 25.

Similarly, the size correction winding of the horizontal static convergence and size correction assembly 27 is serially connected via a line 35 to the horizontal deflection winding of the yoke 23, the horizontal deflection winding being itself connected via a line 37 to the horizontal output stage 39. In this manner, a sawtooth deflection current flows between the horizontal output stage and ground through the horizontal deflection winding of the yoke 23 and the horizontal size correction winding of the horizontal static convergence size correction assembly 27.

In FIGURE 2, portions of the electron guns 9 and 11 are broken away to more clearly show the electron guns 9, 11 and 13 and the circuit connections shown in FIG- URE l have been omitted for purposes of clarity.

The operation of the system shown in FIGURES 1 and 2 is such that the deflection yoke 23 produces an optimally non-uniform field which inherently corrects for parabolic deflection errors by providing a cross-hatch raster from each electron beam 15, 17 and 19 which exhibits substantial parallelism across the entire face 7 of the cathode ray tube. The three cross-hatch rasters thus produced although parallel are found to vary slightly in size. Accordingly, the same sawtooth deflection currents applied to the deflection yoke 23 are applied to the size deflection windings of the vertical static convergence and size correction assembly and the horizontal static convergence and size correction assembly to achieve substantial registry of the three rasters across the face of the cathode ray tube.

In understanding the invention, it is useful to consider the type of parabolic errors produced by the prior art system wherein a deflection yoke providing a substantially uniform field was employed. Thus, referring to FIGURE 3, there is shown a view from the front of the faceplate 7 of the type raster produced when a uniform field yoke is employed. It is seen that in such a system even where the beam 17 from the green gun 11 produces a plurality of vertical lines 41, inherent parabolic errors result in splitting of the electron beams 15 and 19 produced by the blue and red guns 9 and 13 respectively. Thus, as depicted, the beam 15 produced by the blue gun 9 instead of traversing the desired vertical paths describes parabolic paths 45, the parabolic error being seen to increase toward the edge of the tube. Similarly, inherent parabolic errors cause the beam 19 generated by the red gun 13 to describe parabolic paths 43 rather than the desired vertical paths, the para-bolic error again increasing toward the edge of the tube. The manner in which the electron beams cross to produce the type of errors shown in FIG- URE 3 is seen by reference to the electron beams 15', 17 and 19 and also 15", 17" and 19" of FIGURE 1.

As is well known, the type of parabolic errors shown in FIGURE 3 are inherent in the prior art systems due to the tube geometry and the action of the axial component of the deflection field on the beams as the beams are deflected.

In the prior art, the severe beam splitting depicted in FIGURE 3 could only be corrected through the use of a complicated predeflection system, a complex and difficult to generate correction signal being utilized for this purpose. In accordance with the present invention, the prior art problems are overcome through the use of an optimally non-uniform deflection yoke which inherently eliminates the parabolic errors depicted in FIGURE 3 by producing three linear rasters exhibiting parallelism at all points.

More specifically, it is found that by adding quadrature flux components to a substantially uniform deflection field, a deflection field can be achieved which will inherently correct for the parabolic errors depicted in FIGURE 3. Thus, referring to FIGURES 4 and 5 there is depisted schematically the manner in which quadrature flux components may be added to the vertical and horizontal deflection windings respectively. Referring specifically to FIGURE 4 there is shown a ferrite core 47 upon which is positioned a toroidally wound horizontal deflection winding. The core 47 may take the shape of a generally truncated conical member and be formed from a ferrite material.

The horizontal deflection winding comprises a pair of terminals 49 and 51, a main winding comprising windings 53 and 55 and four correction windings 57, 59, 61 and 63.

It will be seen that starting from terminals 51 the various windings are serially connected in the following order, namely winding 61, winding 63, winding 57, winding 59, winding 55 and winding 53. In this manner the flux produced by the respective winding 53 and 55 of the main winding is additive to produce a substantially uniform main deflection field. Further the flux produced by each of the correction windings 57, 59, 61 and 63 includes a component in quadrature to the main field and a component bucking the main field. Since the correction windings contain fewer turns than the main field windings, the

flux produced by these windings will have a pronounced effect only on electron beams in the immediate vicinity thereof.

Thus for example, Where a sawtooth deflection wave 65 is applied to the terminal 51 such that current flow in the deflection winding is in the direction of arrow 67 during the negative half cycle of the sawtooth, the windings 53 and 55 produce a substantially uniform main field having a direction represented by the arrows 69 and 71 while the correction windings 57, 59, 61 and 63- produce fields having directions represented by the arrows 73, 75, 77 and 79 respectively.

It will be appreciated that the flux produced by each of the correction windings 57, 59, 61 and 63 include a quadrature component and a component bucking the main field as indicated for example by arrows 81 and 83 respectively with respect to correction winding 57. It will be seen that the main field as represented by the arrows 69 and 71 in conjunction with the component of the correction flux which bucks the main field produces a force on the beams as indicated by the arrow 85 during the negative half cycle of the sawtooth wave 65, the beams being directed out of the plane of the drawing as shown. Similarly, the quadrature component of the flux produced by each correction Winding produces a force in a vertical direction on the beams in the vicinity of the correction windings.

Referring to FIGURE 5 there is shown a vertical deflection winding including a pair of terminals 86 and 87. The winding comprises windings 89 and 91 of the main winding and correction windings 93, 95, 97 and 99. It will be seen that starting from terminal 86, the correction windings and main windings are serially connected in the following order, namely winding 99, winding 97, winding 93, winding 95, winding 89, and winding 91.

The flux produced by the windings 89' and 91 is additive to produce a substantially uniform main deflection field while the flux produced by each of the correction windings 93, 95, 97 and 99 includes a component in quadrature with the main field and a component which adds to the main field.

Thus, for example where a sawtooth deflection wave 101 is applied between the terminals 86 and 87 such that current through the deflection winding flows in the direction of the arrow 103 during the negative half cycle of the deflection wave so that the windings 89 and 91 produce a main field having a direction represented by arrows 105 and 107 while the correction windings 93, 95, 97 and 99 produce fields having directions represented by the arrows 109, 111, 113, and 115 respectively.

It will be appreciated that in a manner similar to the horizontal deflection winding shown in FIGURE 4, the flux produced by each of the correction windings includes a quadrature component as well as a component that adds to the main field as indicated for example by arrows 117 and 119 respectively with respect to correction winding 93. The main field indicated by arrows 105 and 107 in conjunction with the component of the correction field which adds thereto provides a force on the beams as indicated by arrow 121 dupring the negative half cycle of the sawtooth wave 101, the beams again being directed out of the plane of the drawing as shown. Further, the quadrature component of the correction fields as represented for example by arrow 117 produces a correcting force in a horizontal direction, this correcting force being most pronounced in the vicinity of the various correcting windings.

In accordance with the invention, the main horizontal and vertical windings and the associated correction winding shown in FIGURES 4 and 5 are so related that the correction forces provided by the correction windings produce three linear rasters exhibiting substantial registry across the entire face of the cathode ray tube.

In a preferred embodiment of the invention, the windings shown separately in FIGURES 4 and 5 are combined into a composite winding distribution as depicted in FIG- URE 6.

In the composite distribution of the preferred embodiment of FIGURE 6, each of the main vertical and horizontal deflection windings have been combined with their associated correction windings as shown in FIGURES 4 and 5. Thus, the main horizontal winding 53 of FIGURE 4 has been combined with the correction windings 57 and 59 while the main horizontal winding 55 has been combined with the correction windings 61 and 63. Similarly, the main vertical deflection winding 89 of FIGURE 5 is combined with correction windings 93 and while the main vertical winding 91 is combined with correction windings 97 and 99. Further, as shown the horizontal and vertical deflection windings are combined to provide a composite distribution which is easily wound on a single core. In this manner the necessity for discrete correction windings is eliminated while producing the same effect.

In FIGURE 6 the composite distribution is shown wound in toroidal fashion on a ferrite core member 123 of generally truncated conical shape. For purposes of simplicity only the turns abutting the inner surface of the core member have been shown. It will be appreciated that these turns will be in closest proximity to the electron beams 15, 17 and 19 and thus will have the greatest effect thereon.

The composite distribution of FIGURE 6 can be easily wound in progressive fashion through the use of four windings. Thus, a first winding represented by the unshaded turns 124 may be started at turn 125 and wound in a counterclockwise direction in progressive fashion to turn 127. A second winding 128 represented by the turns having an x" therein may be initiated at turn 129 and wound in a counterclockwise direction in progressive fashion to turn 131.

The first and second windings thus comprise the vertical deflection winding including the correction windings as shown in FIGURE 5.

Similarly, a third winding 132 represented by the partially shaded turns may be initiated at turn 133 and wound counterclockwise in progressive fashion to turn 135. A fourth winding 136 represented by the completely shaded turns may be initiated at turn 137 and wound in a counterclockwise direction in progressive fashion to turn 139. As depicted, there are seen to be gaps at some positions of the resultant composite winding while at other positions the windings necessarily overlie each other.

The third and fourth turns comprise the horizontal defiection windings including the correction windings shown in FIGURE 4.

A terminal 141 is connected to the turn 127 of the first winding via a lead 143, a terminal 145 being connected to the turn 131 of the second winding via a lead 147. Terminals 141 and 145 thus comprise the input terminals to the vertical deflection winding and serve the function of the terminals 86 and 87 of FIGURE 5.

Similarly, a terminal 149' is connected to the turn 133 of the third winding via a lead 151 while a terminal 153 is connected to turn 137 of the fourth winding via a lead 155. Terminals 149 and 153 thus comprise the input terminals of the horizontal deflection winding and serve the same function as the terminals 49 and 51 of the winding shown in FIGURE 4.

As depicted, the turns 125, 129, 135, and 139 are connected in common through leads 157, 159, 161 and 163 respectively.

It will be seen that in accordance with .an important feature of the invention different distributions are utilized for the horizontal and vertical deflection windings. In accordance with the invention, each of these distributions differ significantly from the distribution utilized in the prior art to achieve a substantially uniform deflection field. Thus, in the preferred embodiment of the invention, distributions represented graphically in FIGURES 7 and 8 were utilized for the vertical and horizontal windings respectively to provide an optimally non-uniform field.

7 Referring to FIGURE 7 there is shown a normalized plot of the vertical winding distribution shown in FIG- URE 6. In the graph of FIGURE 7 the Y axis represents a percentage of the total number of vertical turns in the second quadrant of FIGURE 6 while the X axis represents an angle increasing counterclockwise. The placement of the individual turns is represented by the circles through which the curve is drawn. Accordingly, the curve represents the position of each turn within the quadrant. For purposes of illustration, where 41 vertical turns are employed per quadrant as shown in FIGURE 6, 50% of these turns would be located within a quadrant angle 45 of 35. Accordingly, the 205th turn would be located at a quadrant angle of 35. The vertical winding in the first quadrant is of course a mirror image of that in the second quadrant.

The curve shown in FIGURE 7 can be represented by a Fourier series of the form where the coefficients are generally:

Referring to FIGURE 8 there is shown a normalized plot of the horizontal winding distribution shown in FIGURE 6. In the graph of FIGURE 8 the Y axis represents a percentage of the total number of horizontal turns in the first quadrant of FIGURE 6 while the X axis represents an angle increasing counterclockwise within the quadrant. Again the placement of the individual turns is represented by the circles through which the curve is drawn, each circle representing an individual turn. Accordingly, the curve represents the position of each turn within the quadrant. For purposes of illustration where 31 horizontal turns are employed per quadrant as shown in FIGURE 6, 50% of these turns would be located within a quadrant angle 0 of 25. Accordingly, the 15.5th turn would be located at a quadrant angle of 25. The horizontal winding in the fourth quadrant is of course a mirror image of that in the first quadrant.

The curve shown in FIGURE 8 can be represented by a Fourier series of the form:

Y =S sin (0)+T sin (30) U sin (50) +V sin (76)+W sin (90)+X sin (110) +1 sin (130)-l-Z sin (150) where the coefficients are generally:

beam entry and exit ends of 2.289" and 3.104 respectively. The end surfaces of the ferrite core can be notched or provided with a notched insert to maintain the various turns in the desired location. Such a deflection yoke was found to provide an optimally simplified deflection system for use with the General Electric type 11SP22 color cathode ray tube.

The manner in which the main fields and the correcting fields interact to provide the necessary correcting forces to overcome inherent parabolic errors is extremely complex and difficult to describe since these forces differ from point to point within the field and vary with time.

However, the manner in Which the correctional forces affect the electron beams may be considered with reference to the vector diagrams shown in the first quadrant of FIGURE 6. Thus, for example, where an electron beam directed as shown is positioned somewhere in the first quadrant, the main vertical field B and the main horizontal field B combine to produce a resultant main field B It must be understood that the horizontal field varies at the line rate while the vertical field varies at the field rate. From the vector equation FXT =F it is seen that a force is produced by the main fields on the electron beam identified by the vector F Similarly, the correction field produced by the vertical correction windings B can be resolved into a component B in phase with the main vertical field and a component B in quadrature with the main vertical field. Further, the field produced by the horizontal correction windings produce a correction field B which can be resolved into an in-phase component B and a quadrature component B Thus, a resultant correction field B is provided. The correction fields produce a force P on the electron beam which in conjunction with the force produced by the main field F provides a resultant force F In this manner, correcting forces are applied to the electron beam which eliminate the parabolic errors inherent in the prior art systems.

It will be appreciated that the vector diagram shown in FIGURE 6 represents conditions existing only for a particular time and a particular axial position within the yoke as well as for a particular position within the quadrant. Thus the total correcting forces acting upon each electron beam during its passage through the yoke is the line integral of forces existing at each point along the beam path. The line integral necessarily differs for the beams 15, 17 and 19 since the path of these various beams differ through the yokes as shown in FIGURE 1.

It should be emphasized that through the use of a deflection yoke in accordance with the invention as shown in FIGURE 6 the line integral of the forces acting on the respective electron beam is such that the parabolic errors depicted in FIGURE 3 which take the form of a beam splitting are eliminated and linear rasters are produced as shown in FIGURE 9 which exhibit parallelism at all points.

As depicted in FIGURE 9 the use of the yoke of FIG- URE 6 provides three rasters of differing sizes namely a raster produced by the green gun 11, a raster 167 produced by the blue gun 9, and a raster 169 produced by the red gun 13. The view shown in FIGURE 9 is from the front of the faceplate and the blue raster has been shown by a dotted line, the red raster by a dash-dot line, and the green raster by a dashed line.

Since the three rasters shown in FIGURE 9 differ only in size, in accordance with an important feature of the invention a linear correction signal can be applied to a predefiection system to achieve substantial registry of the three rasters. Thus, in accordance with the invention the necessity for complex parabolic correction signals is completely eliminated and the sawtooth deflection currents can themselves be employed for this purpose.

Referring to FIGURE 10 there is shown a sectional view of the vertical static convergence and size correction systems shown in FIGURE 1, like reference numerals being utilized to identify those components shown in FIGURES 1 and 2.. As depicted, each of the electron beams 15 and 19 passes through a pair of pole pieces positioned within the tube neck 3. Thus, the electron beam 15 passes between a generally C-shaped pole piece 171 and a generally planar pole piece 173. Similarly, the electron beam 19 passes between a generally C-shape-d pole piece 175 and a generally planar pole piece 177. The electron beam 17 is unaffected by the action of the pole pieces on the beams 15 and 19.

A generally E-shaped core member overlies the tube neck in proximity to each of the electron beams 15 and 19. The core member for the beam 15 comprises a generally U-shaped member 179 and a central arm 181 having a cylindrical ferrite magnet 183 rotatably positioned therebetween. A winding 184 provided with terminals 185 and 186 is positioned on the central arm 181 to provide the desired vertical size correction. The ferrite magnet 183 is diagonally polarized as shown and is positioned in suitable grooves in the U-shaped member 179 and the central arm 181.

Similarly, the beam 19 is provided with a generally C-shaped core member 187 and a central arm 189 having a cylindrical ferrite magnet 191 rotatably ositioned therebetween. A ferrite magnet 191 is diagonally polarized in the same manner as the magnet 18-3 and is positioned in suitable grooves in the U-shaped core member 187 and the central arm 189. A vertical size correction winding 192 provided with terminals 193 and 194 is positioned on the central arm 189, the windings 184 and 192 being serially connected as shown.

The operation of the vertical convergence and size correction assembly of FIGURE is such that the magnets 183 and 191 can be rotated to control the magnitude and polarity of the steady state field through which beams and 19 pass. The field is represented by the arrows 195 with respect to beam 15, and arrows 197 with respect to beam 19, the beams being directed into the plane of the drawing as shown. Further, the proximity of the C-shaped core members 179 and 187 to the internal pole pieces 171 and 175 respectively can be varied to control the field magnitude as described and claimed in co-pending application Ser. No. 469,161 filed July 2, 1965, now Patent No. 3,305,807 and assigned to the assignee of the present invention.

In accordance with an important feature of the invention, the sawtooth deflection currents are applied directly to the size correction windings 184 and 192 to apply a linear but time varying correction field to the electron beams 15 and 19 respectively. 'In this manner the vertical size of the blue and red rasters produced by the electron beams 15 and 19 respectively can be controlled to achieve substantial registry with the green raster.

Referring to FIGURE 11 there is shown a sectional view of the horizontal static convergence and size correction assembly shown at FIGURES 1 and 2. As depicted, the beam 17 is shielded by a cylindrical shielding member 199, the beam 15 being provided with a pair of spaced generally V-shaped pole pieces 201 while the beam 19 is provided with a pair of similar V-shaped pole pieces 203.

Each of the beams 15 and 19 is provided with a generally U-shaped core member positioned external to the tube neck 3 in proximity to the pole pieces 201 and 203 respectively. Thus, the beam 15 is provided with a generally U-shaped core member comprising a pair of L- shaped core segments 205 and 207 having a cylindrical ferrite magnet 209 rotatably positioned therebetween. Size correction windings 211 and 213 are provided on the core segments 205 and 207 respectively, the winding 211 being provided with a terminal 214. Similarly, the beam 19 is provided with a pair of generally L-shaped core segments 215 and 217 having a cylindrical ferrite magnet 219 rotatably positioned therebetween. Size correction windings 221 and 223 are positioned on the core segments 215 and 217 respectively and these segments being notched to receive the magnets 209 and 219 respectively. The winding 221 is provided with a terminal 224 as shown.

As depicted, the horizontal size correction windings 211, 213, 223 and 221 are serially connected in the order named.

The operation of the horizontal static convergence and size correction assembly of FIGURE 11 is such that the rotatable magnets 209 and 219 can be rotated to control the magnitude and polarity of the static field acting upon the electron beams 15 and 19 respectively. The flux passing between the pole pieces 201 and the pole pieces 203 is represented by the arrows 225 and 227, respectively, this flux producing forces on the respective beams represented by the arrows 229 and 231 respectively with the beams again being directed into the plane of the drawing as shown. Thus, in a manner similar to the vertical static convergence and size correction assembly, the angular positions of the magnets 209 and 219 can be independently controlled and the proximity of the core segments 215 and 217 to the internal pole pieces 201 and 203 may be varied to statically converge the beams 15, 17 and 19 in the desired fashion. In addition, as with the vertical static convergence and size correction assembly, the sawtooth horizontal deflection current is applied directly to the size correction windings 211, 213, 221 and 223 to control the flux acting upon the electron beams 15 and 19 thereby causing the size of the rasters produced by these electron beams to correspond to that of the green beam.

It will be seen that there are different reasons for the horizontal and vertical size differences shown in FIG- URE 9. Thus, the horizontal size differences result from the action of the deflection yoke in producing correction forces to overcome the parabolic errors inherent in the prior art systems. However, with an in-line gun system as disclosed, the vertical size errors result almost entirely from gun misalignment. Thus, in instances where gun alignment is such that no vertical size errors are produced, it is possible to utilize horizontal size correction alone while eliminating vertical size correction to further simplify the deflection system.

Referring to FIGURE 12 there is shown a schematic diagram of the deflection circuitry of a representative television receiver employing the simplfied deflection system of the invention. In FIGURE 12 like reference numerals have been utilized to identify those elements identified in the previous figures.

As shown, the vertical output stage 33 comprises a vertical driver tube 233 having anode, cathode and control grid electrodes 235, 239 and 237 respectively.

The output of the vertical oscillator (not shown) is applied to the control grid 237 to develop a sawtooth deflection current in the primary of a vertical output transformer 241 connected to the anode 235. The cathode 239 is connected to ground through a vertical linearity control 243 in conventional fashion.

The secondary of the vertical output transformer 241 is connected to the terminal 141 which is in turn connected to the first winding 124 of the composite winding as shown in FIGURE 6. The first winding 124 is connected to the second winding 128 which is in turn connected to a terminal as discussed above.

In accordance with the invention the terminal 145 is directly connected to the terminal of size correction winding 184. Similarly, terminal 186 of size correction winding 184 is directly connected to terminal 193 of size correction winding 192, terminal 194 of size correction winding 192 being grounded as shown. In this manner the identical sawtooth current flowing in the deflection windings 124 and 128 also flows in the correction windings 184 and 192 to provide the necessary size correction as discussed above.

The horizontal output stage 39 comprises a horizontal driver tube 245 having anode, cathode, control grid and screen grid electrodes 247, 249, 251 and 253 respectively.

The output of the horizontal oscillator (not shown) is applied to the control grid 251, the cathode 249 being grounded. The anode 247 is connected to a tap 257 of a conventional auto-transformer 259. The auto-transformer 259 is provided with a damping circuit including damping diode 261 and associated capacitors 263 and 265 and inductor 267. The damping diode 261 serves to develop the desired sawtooth deflection signal across the auto-transformer in well known fashion.

A high voltage rectifier 269 is connected to a tertiary portion of the auto-transformer 259 in conventional fashion to develop a high voltage for application to the cathode ray tube.

The sawtooth deflection signal developed across the auto-transformer 259 is coupled to a secondary winding 271, the secondary winding 271 being connected to the terminal 149 of the winding 132 shown in FIGURE 6. The winding 132 is connected to winding 136 as shown in FIGURE 6, the terminal 153 of winding 136 being directly connected to the terminal 214 of the horizontal size correction winding 211 shown in FIGURE 9. The horizontal size correction windings 211, 213, 223 and 221 are serially connected in the order named, the terminal 224 of winding 221 being connected to the secondary 271 as shown.

A serially connected resistor 273 and capacitor 275 is connected in shunt with the deflection windings 132 and 136 to damp sweep striations in well know fashion while a capacitor 277 is connected in shunt with the winding 136 as shown to balance the capacity across the windings 132 and 136.

The secondary winding 271 is coupled to a blanking winding 279, the winding 279 being utilized to provide the necessary horizontal blanking. Since the blanking circuitry shown in FIGURE forms no part of the present invention it will not be described in detail.

It will be seen in the circuit of FIGURE 10 that as shown in FIGURE 6, the junction between the windings 124 and 128 and the junction between the windings 132 and 136 are connected in common via a lead 281.

The operation of the horizontal output stage 39 is such that sawtooth deflection signal is developed across the secondary 271 to develop a sawtooth deflection current in the windings 132 and 136. In accordance with the invention the identical deflection current flows in the size correction windings 211, 213, 223 and 221 to effect the necessary size correction as discussed above.

The magnitude of the flux produced by the size correction windings can be controlled by varying the proximity of the respective members to the external pole pieces as discussed above. The polarity of the size correction flux required in a particular instance can be selectively controlled by controlling the direction of current flow through the individual windings.

Although the invention has been described with respect to certain specific embodiments, it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the true spirit and scope of the invention.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. A deflection system for a plural in-line beam cathode ray tube having a gun arrangement for producing a plurality of co-planar electron beams impingent upon a viewing screen to produce a raster of a given color thereon, said system comprising:

(a) a deflection yoke positioned intermediate the gun arrangement and the viewing screen in the path of the electron beams and including a vertical winding having toroidally wound turns providing a main field to deflect the electron beams in a vertical direction and a horizontal winding having toroidally wound turns providing a main field to deflect the electron beams in a horizontal direction,

(b) said vertical winding further including toroidally wound turns providing flux components in quadrature to the main vertical field,

(c) said horizontal winding further including toroidally wound turns providing flux components in quadrature to the main horizontal field, there being, with respect to the yoke deflection field, at least one fourth greater number of net flux producing turns in the vertical Winding than in the horizontal winding,

(d) said horizontal and vertical quadrature flux components exerting forces on said beams to produce from each beam a raster substantially parallel at all points to the rasters produced by the other beams but differing in size with respect thereto.

2. A deflection system for a plural in-line beam cathode ray tube having a gun arrangement for producing three co-planar electron beams impingent upon a viewing screen to produce a raster of a given color thereon, said system comprising:

(a) a deflection yoke positioned intermediate the gun arrangement and the viewing screen in the path of the electron beams and including horizontal and vertical windings,

(b) said vertical winding being toroidally wound in a first distribution providing a main field to deflect the electron beams in a vertical direction and flux components in quadrature therewith,

(c) said horizontal winding being toroidally wound in a second distribution different from said first distribution of the vertical winding providing a main field to deflect the electron beams in a horizontal direction and flux components in quadrature therewith, there being, with respect to the yoke deflection field, at least one fourth greater number of net flux producing turns in the vertical winding than in the horizontal winding,

((1) said horizontal and vertical quadrature flux components exerting forces on said beams to produce from each beam a raster substantially parallel at all points to the rasters produced by the other beams but dilfering in size with respect thereto.

3. The deflection system set forth in claim 2 wherein said first distribution is defined by a formula substantially of the form:

where Y represents a percentage of the total number of vertical turns in a quadrant of the deflection yoke and where 4) is an angle increasing in a counterclockwise direction from the vertical axis of the deflection yoke, and said second distribution is defined by a formula substantially of the form:

Y =l05.62 sin 6+7.5l sin (30)+1.51 sin (SM-1.65 sin ()+0.68 sin ()+2.42

sin ()+0.50 sin (136)-0.61 sin (156) where Y represents a percentage of the total number of horizontal turns in a quadrant of the deflection yoke and 0 is an angle increasing in a counterclockwise direction from the horizontal axis of the deflection.

4. The deflection system defined in claim 3 wherein said first distribution comprises a total of 41 winding turns per quadrant and said second distribution comprises a total of 31 winding turns per quadrant.

5. The deflection system defined in claim 2 including horizontal size correction means positioned intermediate said yoke and said gun arrangement to cause the horizontal size of each of said rasters to be substantially identical to the other rasters.

6. The deflection system defined in claim 5 wherein said horizontal size correction means includes horizontal size correction windings directly connected to said deflec tion yoke and being responsive to the linear deflection current from said yoke to apply a linearly varying size correction flux to the outermost of said electron beams to cause the rasters produced by the outermost beams to correspond in size to that produced by the center beam.

7. The deflection system defined in claim 6 wherein said horizontal size correction windings are wound on core segments positioned exterior to the cathode ray tube in proximity to the associated electron beams.

8. The deflection system defined in claim 2 including vertical size correction means positioned intermediate said yoke and said gun arrangement to cause the vertical size of each of said rasters to be substantially identical to the other rasters.

9. The deflection system defined in claim 8 wherein said vertical size correction means includes vertical size correction windings directly connected to said deflection yoke and being responsive to the linear deflection current from said yoke to apply a linearly varying size correction flux to the outermost of said electron beams to cause the rasters produced by the outermost beams to correspond in size to that produced by the center beam.

10. The deflection system defined in claim 9 wherein said size correction windings are wound on core segments positioned exterior to the cathode ray tube in proximity to the associated electron beams.

11. A deflection system for a plural in-line beam cathode ray tube having a gun arrangement for producing a plurality of co-planar electron beams impin-gent upon a viewing screen to produce a raster of a given color thereon, said system comprising:

(a) a deflection yoke positioned intermediate the gun arrangement and the viewing screen in the path of the electron beams and having vertical and horizonal deflection windings including turns providing quadrature flux components exerting forces on said beams to produce from each beam a raster substantially parallel at all points to the rasters produced by the other beams but differing in size with respect thereto,

(b) horizontal size correction means including a horizontal size correction winding positioned intermediate said electron guns and said deflection yoke to apply size correction forces to selected ones of said beams, said horizontal size correction winding being directly connected to said horizontal deflection winding,

(c) horizontal output means connected to said horizontal deflection winding to produce a common linearly varying sawtooth deflection current in said horizontal deflection winding and said horizontal size correction winding.

12. The deflection system defined in claim 11 further including:

(a) vertical size correction means including a vertical size correction winding positioned intermediate said gun arrangement and said deflection yoke to apply vertical size correction forces to selected ones of said beams, said vertical size correction windings being directly connected to said vertical deflection winding,

(b) vertical output means connected to said vertical deflection winding to produce a common linearly varying sawtooth deflection current in said vertical deflection winding and said vertical size correction winding.

13. The deflection system defined in claim 12 wherein the cathode ray tube includes first, second and third linearly arrayed electron guns producing first, second and third linearly arrayed electron beams and said horizontal and vertical size correction forces are applied to the outermost electron beams to cause the rasters produced by the outermost beams to correspond in size to the raster produced by the center beam.

References Cited UNITED STATES PATENTS 6/1965 Nero 315-27 9/1961 Clay 31527 X

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