US2864021A

US2864021A - Color kinescope adjunct

Info

Publication number: US2864021A
Application number: US531940A
Authority: US
Inventors: Angelo G Lazzery
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1955-09-01
Filing date: 1955-09-01
Publication date: 1958-12-09
Anticipated expiration: 1975-12-09

Description

Dec. 9, 1958 A. G. LAZZERY 2,864,021

COLOR KINESCOPE ADJUNCT Filed Sept. 1, 1955 2 Sheets-Sheet l IN VEN TOR. -0 6. ZAZZEK) irrmwsr Dec. 9, 1958 A. G. LAZZERY 2,864,021

COLOR KINESCOPE ADJUNCT Filed Sept. 1, 1955 2 Sheets-Sheet 2 INVIJNTOR. A/vazw ZAZZZWY /7 r ra/ewar COLOR KENESCOFE ADEUNCT Angelo G. Lazzery, Oaklyn, N. l, assignor to Radio Corporation of America, a corporation of Delaware Application September 1, M55, Serial No. 531,344)

6 Claims. (Ci. 3l3--77) The present invention relates to apparatus for controlling the electron beams of cathode ray'tubes and, particularly, to electromagnetic convergence apparatus for use in arrangements in which a plurality of beam components is deflected by a common deflection apparatus.

One type of cathode ray tube with which the present invention may be advantageously employed is a color kinescope of the general type described in an article entitled Deveiopment of a 21-inch Metal Envelope Color Kinescope by Seelen et al. which appeared in the March 1955 issue of RCA Review. Such a tube has a luminescent screen as part of a target structure in which different phosphor areas produce different colored light when excited by electron beam components impinging upon it from different angles, the angle of impingement determining the particular color of the light produced by the screen. The invention also pertains, for example, to a kinescope of the type described in an article entitled A One-Gun Shadow-Mask Color Kinescope by R. R. Law, published in the Proceedings of the l. R. E., October 1951, at page 1194. It is necessary for the satisfactory operation of such kinescopes to effect substantial convergence of the electron beam components at all points of the raster scanned thereby at the target electrode.

In general, such convergence may be eitected by means of apparatus comprising means for producing a plurality of electron beam components which traverse predefiection paths which are spaced respectively about the longitudinal axis of the tube and individual electron magnetic means located respectively adjacent to the predefle-ction beam paths. The electromagnetic means are of such character as to be energized directly from the beam deflection circuitry in a manner to effect the desired beam convergence. Such convergence apparatus is described and illustrated in an article entitled Deflection and Convergence of the 21-inch Color Kinescope which appeared in the same issue of the RCA Review cited above. This type of convergence apparatus is also described in the Seelen et al. article.

In the 21 AX? 22 color kinescope described by Seelen et al., three pairs of radially and inwardly extending pole pieces are provided internally of the kinescope neck. Each pair of pole pieces is thus adapted, when excited by external magnets, to control one of the electron beams for the purpose of effecting the requisite convergence of the beams to the target electrode. One problem which has heretofore existed is that which is concerned with the neck mounting means for securing the external magnets about the tube in proper relation to their associated internal pole pieces.

it is, therefore, a primary object of the present invention to provide a new and improved convergence magnet assembly for use with a color kinescope of "the type described.

V aration, it is necessary that the external magnet pole.

By reason of the fact that the electron guns which produce the several electron beams in such a kinescope 1 Patented Dec. 9, 1958 and the internal pole pieces which operate upon the beams in the convergence function are equi-angularly displaced from each other, the external magnets must also be equi-angularly displaced in order for the external magnets to operate properly with the internal pole pieces. One feature which complicates the structure of the convergence magnet assembly is that the diameter of the tube neck varies from tube to tube within the limits of, for example, Thus, the external convergence magnet assembly must be capable of adapting itself to tube necks of various sizes. In addition to the requirement that the external magnets retain their equi-angular seppieces remain substantially perpendicular to the longitudinal axis of the kinescope, in concentric relation thereto, and that all of the external magnets be perpendicular to the kinescope axis.

Thus, it is a more specific object of the present invention top provide a convergence magnet assembly meeting the foregoing requirements through the agency of relatively simple mechanical apparatus.

In general, the present invention comprises a plurality of foot members, one for each of the external magnets, arranged to form the sides of an equilateral polygon. Each foot member is provided at its ends with means for slidably engaging the ends of adjacent foot members, the sliding engagement being of such character that the foot members are capable of moving only radially with respect to a circle circumscribed by them.

Each of the external convergence magnets, in accordance with one form of the invention, includes a pair of L.-shaped magnetic pole pieces which cooperate with the above-describedinternal pole pieces of the kinescope. Novel means are provided by the present invention for preventing the L-shaped pole pieces from abrading the kinesco-pe neck while maintaining the external pole pieces sufiiciently close to the neck of the kinescope to meet electrical requirements. Spring means secure the plurality of foot members in their polygonal relationship and permit expansion and contraction of the assembled foot members to accommodate various kinescope neck diameters. Such expansion and contraction is, moreover, effected without affecting undesirably the angular relationship between the magnets, the perpendicularity of the magnets to the longitudinal axis or the concentricity of the assembly.

Additional objects and advantages of the present invention will become apparent to those skilled in the art from a study of the following detailed description of the accompanying drawing, in which:

Figure 1 is a side-elevational view of a kinescope provided with a convergence magnet assembly in accordance with the present invention;

Figure 2 is an elevational view, partially in section, of a convergence magnet assembly according to one form of the invention;

Figure 3 is an exploded, isometric view of a portion of the apparatus of Figure 2, with coils omitted in the interest of clarity;

Figure 4 is an isometric view of one of the magnets of Figure 2, with coils omitted:

Figures 5 and 6 are enlarged fragmentary views of portions of the apparatus of Figure 2; and

Figure 7 is an elevational view, partially in section, of another form of the invention.

Reference will first be made to Figure l for a general description of an illustrative embodiment of an electron beam convergence in accordance with the present invention. The system includes a tri-color kinescope 10 which may be ofthe same type as that disclosed in the abovecited Seelen et al. article. It will be understood, ho. ever, that the kinescope may, alternatively, be of other ranged in groups and capable, respectively, of producing light of the ditferent component colors in which the image is to be reproduced. In back of and spaced from the screen 12 is an aperture masking electrode 14 having an aperture for and in alignment with each group of phos-.

phor areas of the screen.

In the particular tube illustrated, the kinescope also has a plurality of electron guns (not shown), equal in number to the number of primary colors in which the image is to be reproduced. The electron guns, three in number, for example, produce the schematically represented

electron beams

17, 18 and 19 by which to energize, respec-- tively, the blue, red and green phosphor areas of the screen 12. When these three electron beams are properly converged at the masking electrode 14 they pass through the apertures thereof from different directions and impinge upon difierent phosphor areas of the various groups so as to produce blue, red and green light. It is to be noted that the size of the phosphor areas, the angles between the beams and the spacing of the mask 14 from the screen 12 as compared with the length of the tube shown are exaggerated for better illustration of the operation of the kinescope.

The details of the construction of such a tube are given in theSeelen et al. article and also in the article by R. R. Law entitled A Three-Gun Shadow-Mask Kinescope" published in the October 1951 issue of Proceedings of the I. R. E. It may be noted that the

electron beams

17, 18 and 19 are suitably modulated in intensity, respectively, by color-representative video signals. The signal source may, for example, be part of a signal receiver of the type illustrated and described in a book entitled Practical Color Television for the Service Industry, revised edition, April 1954, second edition, first printing, published by the RCA Service Co. Inc. 7

Also associated with the color kinescope is a scanning deflection yoke 20 which may be entirely conventional including two pairs of suitably placed coils electrically connected in such manner that, when properly energized, electromagnetic fields are produced to efiect both horizontal and vertical angular deflections of the electron beams so as to scan the rectangular raster.

Energization of the deflection coils may be effected by conventional vertical and horizontal deflection wave generators (not shown) which function to produce substantially sawtooth energy at television vertical and horizontal deflection frequencies so that the fields produced by the yoke 20 are varied in a substantially sawtooth manner.

The beam convergence system of the present invention includes a plurality of electromagnetic field-producing elements indicated diagrammatically by the yoke structure 22 in Figure 1 and shown more clearly in Figure 2. The convergence magnet assembly includes the

magnets

24, 26 and 28 mounted around the neck 30 of the color kinescope adjacent to the predeflection paths of the electron beam components. As will appear in greater detail hereinafter, each of these magnets is located relative to one of the electron beam components so as to influence its associated beam component to the substantial exclusion of the others. It is further to be understood that these magnets are of such character that, when suitably energized, they produce respective fields which are transverse to the associated beam paths.

Before describing the details of the convergence system of the present invention, a brief description will be given of the general manner in which the apparatus functions to produce the desired result. The

convergence magnets

24,, 26 and 28 are energized by unidirectional energy, as through permanent magnets or the like, so as toefiect an initial convergence of the electron beam components at the aperture masking electrode 14. In order to do this, the unidirectional energy of the magnets is effected in such manner that the magnets may be individually energized in different magnitudes. In effecting this initial beam convergence, it is to be understood that the beams may be in any desired one of their dificrent deflected positions. For example, they may be initially converged at the center of the raster to be scanned. Alternatively,

they may be initially converged at one corner of the raster.

The convergence magnets are also dynamically energized by control wave energy derived from a suitable generator so as to effect a variation in the magnitude in the transverse fields produced respectively thereby. These field strength variations are in accordance with a predetermined function of the beam deflection. Variation in the strength of the fields produced by the

magnets

24, 26 and 28 causes corresponding variations in the paths of the electron beam components relative to the longitudinal axis of the tube. Hence, suitable variations are made in the convergence angles between the various beam components so as to produce the desired convergence of the beam components at the masking electrode 13.

For a detailed description of the beam convergence apparatus of the invention, reference will now be made to Figure 2 of the drawing. This figure shows more clearly the positions of the

convergence magnets

24, 26 and 28 relative to each other and to the electron beams to which they are respectively associated. The convergence magnet 24 which is associated with the electron beam 17 is provided with a core comprising two

external pole pieces

32 and 34, each of which is substantially L-shaped so that the combination of the two

pieces

32 and 34 forms a generally U-shaped assembly. Each of the

pole pieces

32 and 34 is provided in its face adjacent the corresponding face of other pole pieces with a generally arcuate recess. Thus, the pole piece 32 has a recess 32a facing an arcuate recess 34a in the pole piece 34. Rotatably supported in the recesses of the pole pieces is a cylindrical magnet 36 which is magnetized permanently along its diameter. The

pole pieces

32 and 34 and their associated permanent magnets are mounted so as to form a continuous U-shaped magnetic path which is in close association with the tube neck 30.

As stated above, the tri-color kinescope 14) illustrated herein by way of example is of the type having internal pole pieces for improved efiici'ency of the convergence magnets. Thus, there is illustrated for each of the

magnets

24, 26 and 28 a pair or radially and inwardly ex tending pole pieces. For example, the magnet 24 is provided with a pair of internal pole pieces 40 and 42 7 associated respectively with the

external pole pieces

32 and 34. It will be understood that, by such means, the reluctance of the magnetic circuit is considerably decreased and that the flux distribution of the field produced'between the internal pole pieces 40 and 42 is considerably improved. While the present invention is illustrated in conjunction with a kinescope having internal pole pieces, it is to be understood that its principles are also applicable to other forms of tri-color kinescopes.

- In the interest of completeness of description, it will be noted that the external pole pieces of each of the magnets are provided with electromagnetic windings such as the windings 44 and 46 shown around the

pole pieces

32 and 34. Each of the magnets is, therefore, adapted to produce a field between its associated internal pole pieces 'for moving its associated beam in a radial direction toward or awayfrom the longitudinal axis of the tube. It will be understood in this connection that the static convergence of the beams is efiected by suitable control of the permanent magnets such as the magnet 36 and that dynamic convergence is controlled by the wave forms applied to the windings such as the windings 44 and 46. Since the operation of such convergence circuits is described in the cited Obert article, no further description thereof is necessary.

Figures 2-5 illustrate in detail a novel arrangement in accordance with the present invention for supporting the beam convergence magnets in operative relationship about the neck of the kinescope. Each of the

convergence magnets

24, 26, and 28 is held in a foot member 5% of a suitable plastic insulating material such as nylon plastic. Each of the foot members 51 Stla and Sit-b is provided with an arcuate inner surface adapted to fit around the cylindrical neck 3% of the kinescope. Since all of the foot members 5 Ella and Silk are identical to each other, the detailed description will be limited to one of the members. The foot member 5d having an arcuate inner surface is further provided with a pair of spaced

apertures

54 and 56 for the reception of the legsof the "bshaped external'pele pieces 32 and 34-; respectively. The

apertures

54 and 56 are of suificient dimensions to accommodate the external poles 32 and 34- snugly. in order to prevent the pole pieces, which may be made of ferrite, for example, from abrading the glass neck 30, the apertures terminate at the inner surface 52 of the foot member in laterally and inwardly extending flanges or webs 56, as shown more clearly in the enlarged, sectional view of Figure 5. Thus, the pole pieces 32 and are prevented by the webs from contacting the neck of the kinescope. Since each of the webs may be formed of 0.010" thickness, the resultant spacing ofthe pole pieces from the internal pole pieces is so slight that substantially no undesirable etfect on the magnetic circuit is produced.

The foot members 5%, 5th: and 5% form, as shown in Figure 2, the sides of an equilateral triangle circumscribing a circle defined by the arcuate inner surface 52 and corresponding to the outer surface of the neck 30 of the kinescope. The foot member St as shown in Figure 3, is bifurcated to provide a pair of slide portions 53 and 6b which are slidably received in guideways in the form of recesses which are formed in the adjacent end of the foot member 5%. Similarly, the end of the foot member Stl, remote from its bifurcated end, is provided with

guideways

62 and 64 which slidably receive the slides and of the foot member Eda.

It will be understood, therefore, that each foot memher is identical to each of the other foot members. Further, the foot members 55 56a and 5d!) are slidably interfitted with the adjacent foot members to form the above-described equilateral triangle. It is important to note that, as shown in the drawing, the upper surface of the slides 53 and so which surfaces, are designated by the same reference numerals bearing the prime (7) nota tion, are guided by the under surface58" and 60 of the flange which defines the guideways 62 and s4. As may be seen from Figure 2, the plane along which the surfaces 53' and 5% meet is a plane parallel to plane drawn tangent to the circle formed by the arcuate inner surfaces of the foot members at the junction of the two foot members in question. This fact is of importance for reasons to be noted hereinafter.

The foot members 51), 59a and Stlb, which may be readily formed by a simple molding operation, are further provided with

apertures

66 and 68 at their opposite ends. Thus, when the foot members are assembled as in Figure 2, the aperture 68 formed in the end of the foot member 50 is in alignment with the aperture 66 in the adjacent end of the foot member 5%. With the foot members assembled, therefore, each apex of the equilateral triangle has a continuous aperture therethrough, as shown by the continuous aperture defined by the holes 66 and 63 shown in Figure 2. These apertures accommodate spring means which serve to exert tensile pressure upon the corners of the triangle to maintain the foot members in a contracted condition. in the form of the invention shown in Figures 25, such spring means take the form of coil tension springs '79. Each spring '70 may, as shown in Figures 2 and 3, be provided with two coil portions formed from the same length of spring wire. Each of the springs 7lpasses through the cooperating, aligned

apertures

66,58 located at one of the apices of the triangular assembly of foot members and serves additionally to hold the external magnet pole pieces securely in place in their apertures 54- and 56.

Specifically, a bracket 72 of phosphor-bronze or other suitable non-magnetic material is provided for each pair of

pole pieces

32 and 34. The bracket 72, shown more clearly in Figure 4, has downwardly-extending flanges 76 along its longitudinal edges to form a channel for the reception of

pole pieces

32 and 34. The channel 72 is additionally provided with a pair of downwardly-bent spring ears 78 which, for simplicity of construction, may

be struck out from the ends of the bracket, leaving the apertures 3t

magnetic pole pieces

32 and 34 to urge the pole pieces against the cylindrical magnet 36 thereby securing its three members in their proper relationship. In order to secure the permanent magnet 36 frictionally between pole pieces 32 and 3 2, a bent spring wire 82 is booked at its ends under the spring cars 73 and urges against an annular groove 84- in the shaft of the magnet 36. The springs Tllwhich may also be formed of phosphor-bronze, for example, are hooked at their opposite ends to engage the apertures in the brackets '72.

In this manner, the springs 70 serve to secure the various elements of the convergence magnet assembly into a unitary mount, in which the brackets '72 are urged toward their respective foot members and the foot merrbers are resiliently urged into tighter contact with each other. Since, in the specific tri-color kinescope described herein, the several beam components 17, 18 and l?- are equi-spaced about the longitudinal axis of the kinescope, it will be understood that each of the three foot members subtends an arc of substantially so that the external magnets are maintained with spacings therebetween of 120. By virtue of the equi-angular spacing of the

magnets

24, 26 and 28, the external pole pieces of the magnets are maintained in proper physical location with respect to the internal pole pieces of the kinescope to Provide the desired low reluctance magnetic path.

It will further be recognized from the foregoing that the convergence magnet mount of the present invention may be readily expanded to fit over the enlarged socket end 30a of the kinescope and, moreover, that the triangular mount, by reason of equal spring pressures on the foot members remains in the desired equilateral configuration. This latter action stems additionally from the fact that the cooperating surfaces 58' and 58" of the slides and guideways formed in the foot members are parallel to planes drawn tangent to the neck of the kinescope at the location of the apices of the assembly. Stated otherwise, the tangential guideways 58 and 6% permit the foot members to move only radially. Thus, regardless of the extent to which the foot members are pulled apart, as to accommodate larger neck diameters, the magnets carried by the foot members retain their equiangular spacing. Moreover, the magnets remain perpendicular to the axis of the kinescope and concentric with respect thereto. Since the foot members are of appreciable axial length (e. g., and since the springs exert equal pressures on the foot members, the mount in its entirety remains perpendicular to the longitudinal axis of the tube.

As shown in Figure 6, the bifurcated end of the foot member 50 may be formed such that its slide portion has parallel surfaces 58, in which event the cooperating surfaces 53 of the guideway 58 would also be parallel. The tapered construction of the guide members shown in Figures 2 and 3 may be employed for simplicity of the molding operation. The parallel configuration of Figure 6, however, affords additional insurance against non- The spring ears '78 clampingly engage the" those elements of Figure 7 corresponding'to the parts of Figure 2 are designated by the same reference characters. In the form of the invention shown in Figure 7, the elongated coil springs are replaced by C-shaped tension springs 90, arranged as shown with the ends of the Us engaging apertures 92 and 94 formed in the foot members. The 10 external pole pieces are held in place by means of spring members in the form of neoprene bands 96 whose ends are hooked on to lugs 98 which extend from the foot member, as shown.

The form of the invention shown in Figure 7 is particularly adapted for use in arrangements wherein the ex- 'ternal pole pieces are continuous horeshoes, that is, with each convergence magnet having a continuous U-shaped core instead of one made of two L-shaped cores. With a continuous horseshoe core such as the core 100, the static convergence may be eifected in a known manner through the use of suitable direct current windings associated with the magnets. The core 100 has a rounded bright portion .for increased strength. 7 Having thus described my invention, what I claim as t new and desire to secure by Letters Patent is:

1. Electromagnetic convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for each of said magnets, said foot members being arranged around such tube and having mating means at their extremities for slidably engaging the extremities of adjacent foot members, said' mating means being arranged to permit substantially only radial movement of said foot members' 2. Electromagnetic convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for at) each of said magnets, each foot member having a slide portion at one extremity and a guideway at its other extremity, said foot members being equilaterally disposed and arranged so that the slide portion of each foot member slidably engages the guideway of the adjacent foot member. V

3. Electromagnet convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for each of said magnets, each foot member having a slide portion at one extremity and a guideway at its other extremity, said foot members being arranged so that the .slide portion of each foot member slidably engages the guideway of the adjacent foot membenand means for resiliently urging said foot members inwardly toward the center of such polygon.

4. Electromagnetic convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for each of said magnets, each foot member having a slide portion at one extremity and a guideway at its other extremity, said foot members being arranged so that the 'slide portion of each foot member slidably engages the guideway of the adjacent foot member, said slide portions and guideways having cooperating surfaces which are parallel to planes tangent to a circle circumscribed by such foot members.

5. Electromagnetic convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for each of said magnets, each foot member having a slide portion at one extremity and a guideway at its other extremity, said foot members being arranged along the sides of an equilateral polygon in which the slide portion of each foot member slidably engages the guideway of the adjacent foot member, said slide portions and guideways having cooperating surfaces which are parallel to planes tangent to a circle circumscribed by such polygon, and spring means cooperating with the extremities of adjacent foot members for urging said foot members inwardly toward the center of such polygon. V

6. Electromagnetic convergence apparatus for a cathode ray tube, which apparatus comprises: a plurality of magnets and means for holding said magnets in spaced relationship, said means comprising a foot member for each of said magnets, each foot member having a slide portion at one extremity and a guideway at its other extremity, said foot members being arranged along the sides of an equilateral triangle in which the slide portion of each foot member slidably engages the guideway of the adjacent foot member, said slide portions and guideways having cooperating surfaces which are parallel to planes tangent to a circle circumscribed by such triangle.

References Cited in the file of this patent UNITED STATES PATENTS 2,440,403 Jackson Apr. 27, 1948 2,749,486 Gould June 5, 1956 2,766,393 Casey Oct. 9, 1956 2,791,709 Landes et a1. May 7, 1957