US3467881A - Color picture tube - Google Patents

Description

Sept 16, 1959 AKI oHGosHl ET AL 3,467,881

COLOR PICTURE TUBE Filed April 4 1968 4 Sheets-Sheet. 1

u) l d Ofewn's Sept. 16, 1969 Amo oHGosHl ET AL 3,457,331

COLOR PICTURE TUBE Filed April 4, 1968 4 Sheets-Sheet 2 Sept. 16, 1969 AKlQ QHGQsHl ET AL 3,467,881

COLOR PICTURE TUBE 4 Sheets-Sheet 5 Filed April 4, 1968 mgmt m@ Ow MW um @m A mm V. N03@ Q@ v0 n@ .b

mw mw BY Salus/w Sur/74m SEMQ/ NAf/70M Sept. 16, 1969 Amo OHGOSH; ET AL 3,467,881

COLOR PICTURE TUBE 4 Sheets-Sheet 4,

Filed April 4 1968 U.S. Cl. 315-13 12 Claims ABSTRACT F THE DISCLOSURE A new and improved color picture tube system of the single-gun, plural-beam type is provided and includes electron beam deflection means which comprise first and second, successively arranged electron beam detlectors to insure that the respective electron beams will be properly converged to properly strike the different color phosphor stripes of the color phosphor screen throughout the entire extent of the latter.

This invention relates to a new and improved color picture tube system and, more particularly, to a new and improved single-gun, plural-beam type color picture tube system.

Although single-gun, plural-beam type color picture tube systems are known in the prior art, the inability thereof to maintain the plural beams emitted from the system electron gun properly focussed and converged at the color phosphor screen has been known to give rise to serious operating difficulties. In addition, difficulties have been encountered in preventing the beam spots on the color phosphor screen from becoming blurred, due to coma and/or astigmatism of the electron gun lens, to result in color picture reproduction of substandard quality.

Preferably, in color picture tube systems of this nature, the distance between the color phosphor screen and the screen, or beam landing position determining, grid or shadow-mask should be relatively short to minimize the axial length of the color picture tube. In addition, it is of significant importance to the provision of high quality, color picture reproduction that a precise relationship in position be maintained between the portion of the screen grid or mask through which the beams pass and the color phosphor stripes of the color phosphor screen. In meeting these requirements, it is preferable that the angle formed by the electron beams at the common spot of convergence thereof at the screen grid or mask be made as large as is possible. This angle can be increased by either increasing the distance between the three electron beams at the surface of the beam generating cathode or by increasing the distance between the main lens of the electron gun and the beam deection means. Increase in the spacing of the electron beams at the generating surface thereof, however, makes diflicult the imparting of a sufficient focussing effect on the beams whereby beam resolution, and accordingly, picture quality, are deteriorated. Similarly, any increase in the main lens deflection means distance is undesirable in that it of course results in increase in the overall length of the color picture tube.

In instances wherein deviations occur in the respective predetermined positions of the screen grid or electron beam deflection means relative to the color screen in single-gun, plural-beam type color picture tube systems, the respective beams will resultantly fail to strike the proper phosphor stripes or dots on the color phosphor screen despite the fact that satisfactory convergence 1s aiiorded to the beams by fine adjustment of the deflection voltage applied to the deflection means. Further, such component position deviations will result in variation of 3,467,881 Patented Sept. 16, 1969 the incident angles of the three electron beams with respect to the color phosphor screen to result in the beams striking different portions of the latter, for example, the screen central portions and the screen boundary portions, at different incident angles and make impossible the provision of uniform brightness over the entire color phosphor screen surface. Conversely, if fine adjustment of the voltage applied to the electron beam deflection means is utilized instead to insure that each of the three beams will strike precisely the proper phosphor stripe on the color phosphor screen, it then becomes impossible to impart satisfactory convergence to the beams through use of this same deection voltage adjustment.

By this invention is provided a new and improved color picture tube system which, as disclosed herein, is of the three-beam, single-gun type and obviates the above-discussed disadvantages of the prior art systems. More specilically, the color picture tube system of this invention comprises electron beam deflection means which include first and second electron beam deflectors arranged successively between the beam generating cathode and the color phosphor screen. By the use of these tirst and second electron beam deflectors it is made possible to insure proper convergence of the beams at the screen grid common spot, and proper striking thereby of the color phosphor stripes, while enabling superior electron beam focussing and some measure of cathode ray tube miniaturization. In addition, the three electron beams provided by the beam generating source are caused to pass through the center of the main forcussing lens of the single electron gun with one of the beams emerging therefrom along the optical axis thereof, and the other two of the beams emerging therefrom in divergent directions. Subsequently, the other two electron beams are deflected by the respective first and second beam deflectors, which are interposed between the color phosphor screen and the equivalent main lens of the single electron gun, and are caused to converge with the one electron beam at a common spot at a screen grid or mask provided in front of the color phosphor screen, to in turn properly strike the respective color phosphor stripes of the latter and insure excellent picture quality. Since all of the said electron beams are made to pass through the center of the equivalent main lens of the electron gun in the color picture tube system of this invention, the three beams will be substantially free from the influence of coma and/ or astigmatism of the said electron gun lens whereby blurring of the color phosphor screen beam spots will be substantially prevented.

It is, accordingly, a primary object of this invention to provide a new and improved color picture tube system of the single-gun, plural-beam type having electron beam defiection means which comprise a plurality of successively arranged electron beam deflectors to insure that the plural electron beams will be properly converged to properly strike the different color phosphor stripes of the color phosphor screen throughout the entire extent of the latter.

Another object of this invention is the provision of a single-gun, plural-beam type color picture tube system wherein the electron beams are passed through the optical center of the electron gun main lens to insure that the beams are substantially free from the influence of coma and/ or astigmatism of the former and result in the prevention of beam spot blurring on the face of the color phosphor screen.

Still another object of this invention is the provision of a singleegun, plural-beam type color picture tube system which is somewhat miniaturized and may be readily manufactured through the use of existing techniques.

The above and other objects and advantages of this invention are believed made clear by the following detailed description thereof taken in conjunction with the accompanying drawings wherein FIG. 1 is a schematic diagram depicting a single-gun, plural-beam type color picture tube system constructed in accordance with the teachings of the prior art;

FIG. 2 is a schematic diagram depicting the optical equivalent or analogy of the tube system of FIG. l;

FIG. 3 is a schematic diagram depicting an embodiment of a single-gun, plural-beam type color picture tube system constructed in accordance with the teachings of this invention;

FIG. 4 is a schematic diagram depicting the optical equivalent or analogy of the tube system of FIG. 3;

FIG. 5 is a schematic diagram depicting another embodiment of a single-gun, plural-beam type color picture tube system constructed in accordance with the teachings of this invention;

FIG. 6 is a schematic diagram depicting still another embodiment of a single-gun, plural-beam type color picture tube system constructed in accordance with the teachings of this invention;

FIG. 7 is an end view which illustrates the magnetic convergence deflector means utilized in the tube system of FIG. 6; and

FIG. 8 is a schematic diagram depicting still another embodiment of the single-gun, plural-beam type color picture tube system constructed in accordance with the teachings of this invention.

To provide for clearer understanding of this invention, a single-gun, plural-beam type color picture tube system of the prior art, wherein use is made of a chromatron type color picture tube of the single-gun, three-beam type, will initially be described with reference to FIGS. l and 2. Thus, as seen in FIG. l, a prior art color picture tube system 10 comprises an electron gun A which includes a cathode K having the electron beam generating sources KR, KG and KB. A first control grid G1, comprising three grid member G1R, GlG, and G1R is supported in slightly spaced, opposed relationship with the electron-emitting end surface 12 of the cathode K. Apertures glR, glG and glR, are respectively formed as shown in the said grid members, and a common grid G2 is disposed in the depicted, slightly spaced opposed relationship with the grid G1. The common grid G2 comprises apertures g2R, g2G, and g2B formed therein as shown in alignment with the apertures of the said three grid members. The grid G2 is cup-shaped to include an end plate 14 through which the apertures g2R, g2G and 12B extend at spaced locations on a diametrical line, and a cylindrical portion 16 which extends axially as shown in the direction away from control grid G1.

Sequentially arranged at axially spaced points in the direction away from the control grid G1 are open-ended, tubular grids or electrodes G3, G4 and G5, with these electrodes, the control grids G1 and G2 and the cathode K being assembled as described by means of suitable, nonillustrated supports of insulating material in the nature, for example, of glass.

In operating the electron gun A of FIG. l, appropriate voltages are applied to control grids G1 and G2 and to the electrodes G3, G4 and G5. Thus, for example, a voltage of 0 to 400 v. may be applied to the three grid members which constitute the control grid G1, a voltage of 0 to 500 v. may be applied to the control grid G2, a voltage of 13 to 20 kv. may be applied to the electrodes G3 and G5, and a voltage of 0 to 400` v. may be applied to the electrode G4, all using the voltage of cathode K as the reference voltage. As a result, the respective voltage distributions of the grids G1 and G2 and the electrodes G3, G4 and G5, and the respective lengths and diameters thereof, will be substantially identical with those of a unipotential single-beam type electron gun which includes a single, rst grid member and a second grid provided with a single aperture.

With the applied voltage distribution as described above, an electron lens field is established between grid G2 and the end 18 of electrode G3, and this electron lens eld will form the equivalent of an auxiliary lens as indicated in dashed lines at L'. Further, an electron lens teld which is the equivalent of a main lens as indicated in dashed lines at L is formed on the axis of electrode G4 by the electrodes G3, G4 and G5. In one operation of the electron gun A, bias voltages of v., 0 v., 300 v., 2O kv., 200 v., and 20 kv. are applied to the electrode K, the control grids Gl and G2, and the electrodes G3, G4 and G5, respectively.

To effect convergence of the electron beams BR and BB which emerge as shown from the electrode G5 along divergent paths, the electron gun A of FIG. 1 further comprises deiiecting means F which include shielding plates P and P', disposed as shown in spaced, opposed relationship, and beam-converging deflector plates Q and Q' which are respectively disposed as shown in spaced, opposed relation to the outer shielding plate surfaces. The shielding plates P and P', and the deflector plates Q and Q', are disposed so that the electron beams BR, BG and BR pass respective'y between the plates P and Q, between the plates P and P', and between the plates P and Q. A voltage VP, which is equal to the voltage applied to the electrode G5, is applied to the deflector plates P and P', and a voltage VQ, which is lower by 200 v. to 300 v. than the voltage applied to the shielding plates P and P', is applied to the detlector plates Qand Q. Thus, a voltage diierence or detiecting voltage VG will be applied between the plates P and Q and between the plates P' and Q', respectively, to impart the requisite deflecting action to the electron beams BR and BB.

With the system 10 as described, the three electron I Ibeams BR, BG and BB will emanate from the cathode K to pass respectively through the grid member apertures glR, glG, and g1B,'and will be modulated by the red "green and blue video signals which are applied between the cathode K and the grid members G1R, GIG and G1R, respectively. The electron beams BR, BG and BB are then passed through the auxiliary lens as indicated at L' and will then intersect each other at the center of the main lens L. Thereafter, the electron beams BR, BG and BB will tbe passed respectively between the plates Q and P, between the plates P and P', and between the plates P' and Q. Since plates P and P' are of the same potential, electron beam BG will not be deected. The existence of the deflecting voltage VG will, however, function to deflect electron beam BR as it passes between the plates P and Q, and to deflect electron beam BB as it passes between plates P' and Q' whereupon the said electron beams will be directed in the depicted converging manner for impingement of a picture element on the color phosphor screen S.

The color phosphor screen S is similar to color screens of the chromatron type and is formed by a successive arrangement of sets of red, green and blue phosphor stripes SR, SG and SB each of which sets constitutes a color picture element. Spaced as shown from the screen S is a screen grid GP comprising grid wires gp pairs of which are disposed as shown in general alignment with the sets of the respective phosphor stripes SR, SG and SB. A relatively high, post-focussing voltage VM is applied as indicated to the screen grid GP. The voltage VM is lower than the voltages applied to the electrodes G3 and G5, and the shielding plates P and P', but is sufficiently high, as for example 5 kv. to 7 kv., to operate the grid GR.

The electron beams BR, BG and BB converge as shown at a predetermined angle at a common spot between the two grid wires gp of a grid wire pair and diverge therefrom in such manner that the electron beam BR strikes the red phosphor stripe SR, the electron beam BG strikes the green phosphor stripe SG, and the electron beam BB strikes the blue phosphor stripe SB. Thus, the said cornmon spot may be understood to correspond to the depicted set of phosphor stripes. Non-illustrated horizontal and vertical electron lbeam deilection means would, of course, be provided intermediate the neck portion of the non-illustrated cathode ray tube structure to effect electron beam scanning of the color phosphor screen S in conventional manner. Thus it may be understood whereby the application of the rcd, green and blue color video signals between the cathode K and the grids G1R, G1G and G1B, respectively, will function to intensity modulate the three electron beams BB, BG and BB to result in the provision of a color picture on the color screen S.

In the color tube system of FIG. l, the electron beams BB, BG and BB are focused by the passage thereof through the center of the main lens L whereby the beams will be substantially unaffected by coma and/ or astigmatism of the said main lens to thus substantially prevent the blurring of the beam spots on the color phosphor screen S. The distance between the grid GB and the color phosphor screen S will be predetermined by the axial length of the non-illustrated cathode ray tube face portion. In order to achieve accurate correspondence between the respective grid wire gp and phosphor stripe set positions, it is desirable that the said predetermined distance be made as small as possible. However, any decrease in this predetermined distance must be accompanied by an increase in the respective incident angles of the electron beams BB and BB with respect to the grid G, More specifically, and as now described in detail with reference to the optical analogy diagram of FIG. 2, the following conditions should be satisfied:

d m12 d s HIT s "Zz-'3D wherein l1 is the distance between the central plane 20 of the decctor means F and the central plane 21 of the grid GP; I2 is the distance between the central plane 21 and the color phosphor screen S; d is the width of the respective color phosphor stripes; D is the distance between the points at which the electron beams BB and BB pass through the central plane and the point at which the electron beam BG passes therethrough; and PT is the distance between adjacent grid wires gp, otherwise referred to as the screen grid pitch.

Thus, to reduce l2 or l1, the distance D must be Ancreased since each of l2 and l1 are inversely proportional to D. If I3 is the distance between the plane 22 of the cathode face 12 and the central plane 23 of the main lens L; 1.1 is the distance between the respective central planes 23 and 20; and the angle 0 is the angle between either of the electron beams BR or BB with respect t0 electron beam BG, it then becomes clear that the distance ID can only be increased by increasing either of 0 or I4.

Increase of 0 will, however, require an increase in the distance U which is the distance on the face 12 of the cathode K between the emission points of either of electron beams BB or BB and the emission point of electron beam BG, and any increase in the distance U will, of course, make more difficult the application of a sufficient and uniform focussing force to all of the electron beams and will give rise to the possibility that the color picture resolution may be deteriorated. Similarly, it is not desirable to increase I4 since this would require a corresponding increase in the overall length of the non-illustrated cathode ray tube. Further, it is to be understood that any deviation in the distance l2 from its predetermined value or deviation in the position of the central plane 20 will result, for example, in shifting of the electron beams BR and BG to the extent that the same may tend to respectively strike the green phosphor stripe SG or the red phosphor stripe SB of the adjacent phosphor stripe sets with highly disadvantageous result as should be obvious, and this will occur despite adjustment of the convergence voltage which is applied to the convergence dellector means F to provide the possible electron beam convergence. In addition, change in the distance I2 will result in corresponding change in the incident angle of each of the electron beams at the central plane 21 of the grip GP whereby the position where each of the electron beams strikes the color phosphor screen S will be shifted and the conditions under which the respective beams strike the color phosphor screen S will be different in the upper and lower end portions of the cathode ray tube than they are in the central portions of the latter. Conversely, if the voltage applied to the convergence deilector means F is finely adjusted to prevent shifting of the electron beam striking positions on the color phosphor screen S, it then becomes impossible to achieve proper convergence of the electron beams in the central portions of the screen. It therefore becomes most difficult to simultaneously achieve proper convergence of the electron beams BB, BG and BB and proper striking of the said electron beams on the respective color phosphor stripe sets.

In accordance with this invention there is provided a new and improved color picture tube system which is capable of eifectively solving the aforementioned problems as arise in the operation of the color picture tube systems of the prior art.

Referring now to FIG. 3, there is shown therein an embodiment of the color picture tube system of this invention, as indicated generally at 30, which includes a chromatron type color picture tube of the single-gun, three-beam type as described hereinabove with regard to the prior art color tube system of FIG. l. In the system of FIG. 3, the electron gun is indicated generally at A1 and has a construction similar to that of the electron gun A of FIG. 1. Accordingly, corresponding parts will be identied with corresponding reference symbols whereby it may be understood that electron gun A1 comprises, in the manner of electron gun A, a cathode K, control grids G1 and G2, and electrodes G2, G1 and G5.

Voltages, based as before on the cathode voltages, which are equal to those described with reference to FIG. l are applied to the control grids G1 and G2 and the electrodes G2, G4 and G5 of the electron gun A1 whereby the electron beams BB, BG and BB which emanate from the gun cathode K are passed through apertures gm, g1G, and g1B of the control grid G1, apertures g2B, g2G and gzB of the ycontrol grid G2, and then through the auxiliary lens L by which the electron -beams are converged at the optical center of the main lens L with the electron beams BB and BB emerging from the latter as before along divergent paths.

Included in the deflecting means F1 of FIG. 3 are spaced electrode plates P and P between which the electron beam BG will pass. At the electron gun side of the electrode plates P and P', electrode plates Q1 and Q1 are disposed as shown in spaced, opposed relationship with the outer faces of the electrode plates P and P. Thus, the electron beams BB and BB will pass respectively between the electrode plates P and Q, and the electrode plates P and Q1. Plates H and H are disposed as shown adjacent the respective electrode plates P and P' in opposed relationship with the outer faces of the latter, and electrode plates Q2 and Q2 are in turn disposed as shown in spaced manner from the outer faces of the plates H and H and in opposed relationship therewith. Thus, the electron beams BB and BB will pass respectively between the plates H and Q2 and between the plates H and Q2. In this instance, the axial extent of the electrode plates Q2 and Q2 is made greater than the axial extent of the electrode plates Q1 and Q'1. Preferably, the electrode plates P and P are bent as shown so that the space therebetween increases gradually in the direction of the color phosphor screen S over a distance which extends from the area of the screen-side edges of the electrode plates Q1 and Q1 to the central area of the plates H and H. In similar manner, the respective plates H and H and Q2 and Q2 are bent so as to maintain the respective inner faces thereof substantially parallel with the respective outer faces of electrode plates P and P'. This bending of the respective plates may, however, be rendered unnecessary by increase in the respective spacing therebetween.

The electrode plates P, P', Q2 and Q2 are electrically connected as shown to terminal TB to which is applied a voltage VP which is equal to the voltages applied to the electrodes G3 and G5 and will thus range from 13 kv. to 20 kv. In like manner, the plates H, H', Q1, and Q1 are electrically connected and coupled to a terminal TQ to which is applied a voltage V which exceeds the voltage VP by a voltage VC ranging from 200 v. to 300 v. To this effect, an equivalent convergence deilecting voltage source VS is connected as shown across the terminals TP and TQ.

As a result of the above, it may be understood that the deflecting means F1 will include a rst deector f1 as constituted by the electrode plates P and P', P and Q1, and P and Q1, and a second deflector f2 as constituted by the electrode plates P `and P', H and Q2 and H and Q'2. The respective rst and second deectors f1 and f2 are successively arranged as shown in the paths of the electron beams BR, BG `and BB. Thus, the electron beams BR and BB will pass respectively between the plates P and Q1 and between the plates B and Q1 and will be deliected in divergent directions by the first deflector f1. Thereafter, in passing respectively between the electrode plates H and Q2 and between the electrode plates H and Q2, lthe electron beams BR and BB will be deflected in convergent directions by the second deflector f2.

In this embodiment of my invention, the axial extent of the rst deector f1 is made greater than the axial extent of the second deector f2, and a difference in deflection sensitivity is provided therebetween so that the electron beams BR, BG and BB may again be converged at the common spot at the grid Gp. Thus it may be understood that by the application of red, green and blue color -video signals bteWeen the cathode K and the grid G1 respectively, the three electron beams BR, BG and BB will be intensity modulated, whereby a color picture is provided on the color phosphor screen S.

As indicated in the optical equivalent or analogy diagram of FIG. 4, the distance Z2 is measured between the central plane 21 of the grid GP and the color phosphor screen S, the distance l is measured between the face 12 of the cathode K and the central plane 23 of the main lens L, the distance (I4-H1) is measured between the respective central planes 23 and 21, and the distance d 1s the width of one of the color phosphor stripes, with al1 of these distances being equal to the correspondingly identified distances in the optical analogy or equivalent dragram of the FIGURE 2. Accordingly, the angle .0 between the respective electron beams prior to the mc1dence thereof on the central plane 24 of the first deiector f1 may be smaller than the corresponding electron beam angle of FIG. 2 whereupon the distance U between the respective electron beams on the face 12 of the cathode K may be made smaller than the distance U of FIG. 2. Accordingly, the lens system of the electron gun 30 of FIG. 3 may be understood to apply a more uniform focussing action to the respective electron beams BB, BG and BR than does the prior art electron gun of FIG. 1. As a result, significant improvement in the resolution of the color picture produced on the color phosphor screen S of FIG. 3 is made possible.

In addition, the distance D in FIG. 4 as measured between the incidence points of the respective electron beams on the central plane 25 of the second `dellecting means f2 also becomes smaller than the similarly measured distance D of FIG. 1 whereby a more linear deliecting action for enabling the three electron beams to horizontally and vertically scan the color phosphor screen S will be imparted to the three electron beams which are, of course, subjected to the horizontal and vertical deflection action of the non-illustrated horizontal and vertical deflection coils after having passed through the Asecond deflector f2. Consequently, it becomes possible to effectively prevent any distortion of the picture produced on the said color phosphor screen.

Alternatively, by arranging the system of FIG. 3 to make the electron beam angle of FIG. 4 equal to the electron beam angle 0 of FIG. 2, it becomes possible to reduce the overall cathode ray tube length by an amount corresponding to the difference between 0 as indicated in FIG. 4 and 0 as indicated in FIG. 2, to thus provide for some measure of miniaturization of the cathode ray tube.

Since the respective first and second deflectors f1 and f2 of the system 30 of FIG. 3 can be operated through the use of the voltages applied to the terminals Tp and TQ, the power supply circuit for the said deecting means will not be unduly complicated.

Although no description has been made in the foregoing of the application of a horizontal dynamicconverging effect to the respective electron beams BB, BG and BR, it is to be understood that such effect can readily be `applied through the incorporation in the convergence deflecting voltage source VS of FIG. 3, well known means for providing a parabolic wave form voltage in addition to the power supply means which produce the static convergence deiecting rvoltage VG.

As described hereinabove, the electrode plates Q1, Q1, H and H are electrically connected with each other and coupled to the terminal TQ. Alternatively, it is of course possible to separately connect electrode plates Q1 and H to provide a first terminal, to separately connect electrode plates Q1 and H to provide another terminal, and to separately apply detiecting voltages to the said terminals to thereby compensate for the slight unbalance of the side electron beams BB and BB with respect to the center electron beam BG.

In the system embodiment 40 of FIG. 5, the electron gun is indicated generally at A2, the detlecting means at f2, the screen grid at GB, and the color phosphor screen at S, and the respective components thereof which are the same as the respective components of the embodiments of FIGS. 1 and 3 again bear the same identifying reference characters. As illustrated in FIG. 5, the convergence deectng means f2 again comprise first and second deflectors as indicated at f3 and f4. The deflecting means f3 include spaced electrode plates Q1 and Q1 which are positioned as shown in opposed relationship with the outer surfaces of electrode plates P and P which are common to both of the said detlecting means The deliector f4 comprises electrode plates Q2 and Q2 spaced as shown, and electrode plates H and H which are disposed on the outer surfaces of the electrode plates P and P', through the use of insulating material layers I and I', in opposed relationship with the inner surfaces of the electrode plates Q2 and Q2. Thus, upon leaving the electrode gun A, the central electron beam BG will pass substantially undellected between the electrode plates P and P', while the one side electron beam BB will pass between electrode plates B and Q1 and between the electrode plates H and Q2, and the other side electron beam BR will pass in turn between electrode plates P and Q1 and electrode plates H and Q2, respectively.

The electrode plates P and P and Q2 and Q'2 are connected as indicated to a terminal Tp to which is applied to voltage V. The electrode plates Q1, Q1, H 'and H are coupled to a terminal T and a Voltage V2 from a power source VS is applied to the terminal T2 with the said voltage being equivalent to the voltage VG as described hereinabove with regard to the embodiment of FIG. 3. Thus, in the system of FIG. 5, the electron beams BR and BB will, in passing between the respective electrode plates P and Q1 and P and Q1, be deflected in divergent directions by the first deflector f3. Then, and in passing respectively between the electrode plates H and Q2 and between the electrode plates H' and Q2 of the second deector f4, the electron beams BB and BB will be deliected in convergent directions to thus result in electron beam convergence as shown at the common spot rat the screen grid Gp. As discussed hereinabove with regard to the embodiment of FIG. 3, it is believed readily apparent a horizontal dynamic convergence effect could be provided in the embodiment of FIG. through the provision therein of a horizontal dynamic convergence voltage generating means.

'In the embodiment of FIG. 6 the color tube system is indicated generally at 50, the electron gun is indicated at A2, the electron beam deilecting means at F2, the screen grid at GB, and the color phosphor screen at S, and the same components thereof again bear the same reference characters. The embodiment of FIG. 6 differs from the embodiment of FIGS. 3 and 5 in that the deflecting means F3 of the former 'are of the magnetic, rather than the electrostatic, type. Thus, as seen in FIGS. 6 and 7, the deecting means F3 include a magnetic shield member T which extends, in the manner of the spaced electrode plates P and P of FIG. 5, to be common to both of the first delector, as indicated at f5, `second deflector, as indicated at f6. As best seen in FIG. 7, the magnetic shield member T is of generally rectangular conguration and is deiined respectively by right and left side wall plates 31 and 31', and by upper and lower plates 32 and 32. In operation, the central electron beam BG passes through the -magnetic shield member T without being magnetically deflected.

Since the deilecting means F3 are of generally symmetrica] construction in both of the axial and transverse directions, and in the interests of avoiding unnecessary duplication of drawings, each of FIGS. 6 and 7 will be seen to include, in many instances, a second set of component reference characters placed in parentheses and it is to be understood that this parenthesized second set of reference characters indicates a substantially identical component which lies directly behind the depicted component in each instance. Thus, as seen in FIGS. 6 and 7, at the electron gun side of the magnetic shield member T there is provided a magnetic pole piece member M11 comprising a magnetic plate 33a extending substantially perpendicularly with respect to the side wall plate 31, and a magnetic plate 34a which is bent in such manner as to extend along the annular inner surface of the cathode ray tube neck portion, as indicated in broken lines at N, upwardly from the outer end of the magnetic plate 33a. Also provided at the electron gun side of the magnetic shield member T are a magnetic pole piece member M12 which comprises a magnetic plate 33b disposed in opposition to the magnetic plate 33a, and a magnetic plate 34h which is bent in such manner as to extend along the inner surface of the cathode ray tube neck portion N downwardly from the outer end of the magnetic plate 33h. In addition, and again at the electron gun side of the magnetic shield member T is provided a magnetic pole piece member M'11 which is coniigured in the same shape as the magnetic pole piece member M11 and comprises a magnetic plate 33a' land a magnetic plate 34a extending therefrom. A magnetic pole piece member M12 coniigured in the same shape as the magnetic pole piece member M12 is yalso provided and comprises a magnetic plate 3311' and a magnetic plate 34b' extending therefrom. As best seen in FIG. 7, the respective magnetic pole piece members M11, M12, M11 and M'12 Iare symmetrically disposed around the magnetic shield member T in mutually opposed relationship.

At the color phosphor screen side of the magnetic shield member T, magnetic pole members M21 and M22, conigured in the same shape as the magnetic pole members M11 and M12, are provided adjacent the side wall plate 31 of the said magnetic shield member; and magnetic pole members M21 and M22, configured respectively in the same shapes as the magnetic pole members M11 and M'12, are provided adjacent the side Wall plate 31 of the magnetic shield member T. An annular electromagnet C1 is provided around a part of cathode ray tube neck portion N and consists of a core 36 having a magnetic pole 35a disposed in opposed relationship with the plate 34a of the magnetic pole member M11, and a magnetic pole 35b disposed in opposed relationship with the plate 34h of the magnetic pole member M12, and a winding 37 which is wound as indicated on the core 36. In like manner, an annular electromagent C1 is disposed to the other side of the said tube neck portion, and the former consists of a core 36 having magnetic .poles 35a and 35h disposed in opposed relationship with the plate 34a' of the magnetic pole member M11 and the plate 34h of the magnetic pole member M'12, respectively, and a winding 37 which is wound as shown on the core 36'.

Disposed around the neck portion end to the screen side thereof, is an annular electromagnet C2 which consists of a core having magnetic poles disposed in opposed relationship with the plate 34a of the magnetic pole piece member M21 and the plate 34h of the magnetic pole piece member M22, and a winding 37a is wound around this core. An annular electromagnet `C2 is provided around a part of the neck portion to the screen side of the latter and consists of a core having magnetic poles disposed in opposed relationship to the plate 34a of the magnetic pole piece member M21 and the plate 34h of the magnetic pole piece member M22, and a winding 37a is wound around this core.

In operation, and upon leaving the electron gun A3 as seen in FIG. 6, the electron beam BB will pass undeilected through the magnetic shield member T. The electron beam BB will pass -between the plate 33a of the magnetic pole piece member M11 and the plate 33b of the magnetic pole piece member M12, and will then pass between the plate 33a of the magnetic pole piece member M21 and the plate 33b of the magnetic pole piece member M22. In like manner, the beam BB will pass between the plates 33a and 33b of the respective pole piece members M11 and M'12, and will then pass between the plates 33A and 33B of the respective magnetic pole members M21 and M22. Thus it is believed made clear whereby electromagnetic deiiecting means f5 which are functionally equivalent to the respective electrostatic dellectors f1 and f3 as described hereinabove with reference to the embodiments of FIGS. 3 and 5, will 'be constituted by the magnetic pole piece members M11, M12, M'11 and M'12, electromagnets C1 and C1, and magnetic shield member T. In like manner, electromagnetic deectors f6 which are the equivalent of the respective electrostatic deflectors f2 and f4 as described hereinabove with regard to the embodiments of FIGS. 3 and 5, will be formed by the magnetic pole members M21, M22, M21 and M'22, electromagnets C2 and C'2, and the magnetic shield member T.

A deecting current is supplied from an external source to the winding 37 of the electromagnet C1 to result in the formation of a proportional magnetic ield and the passage of the latter through the magnetic pole members M11 and M12 to apply the requisite deflecting action to the electron beam BB. In this instance, the current is applied to the electromagnet winding 37 in such direction as to elTect the divergent deection of the electron beam BB in its passage between the plates 33a and 33b. In like manner, a deecting current of the same magnitude is applied to the Winding 37 of the electromagnet C1 to provide the requisite magnetic iield through the magnetic pole members M11 and M'12 to impart the requisite divergent deection to the electron beam BB.

Deecting currents likewise applied to the windings 37 and 37 of the respective electromagnets C2 and C2 to eliect the subsequent, convergent deflection of the electron beams BB and BB, it being noted, however, that the deflecting current iiow directions in the respective windings 37 and 37 will, of course, be opposite to those in the windings of the electromagnets C1 and C'1 to insure that the respective electron beams BB and BB are convergently defiected by the deflector f6. Thus the electron beams BR, BGl

and BR will again be converged at the common spot at the screen grid GP. Again, as was the case with the embodiments of FIGS. 3 and 5, horizontal dynamic convergence may be effected in the embodiment of FIG. 6 through the provision of a suitable dynamic convergence current to the windings of the respective electromagnets C1, C1, C2 and C2.

In the embodiment of FIG. 8 the color tube system is indicated generally at 60 and comprises an electron gun as indicated at A4, the electron beam defiecting means as indicated at F4, a screen grid as indicated at GP, and a color phosphor screen as indicated at S, with like components again being identified by like reference characters. Comparison between the embodiment of FIG. and the embodiment of FIG. 8 will make clear that, in the latter, the deflecting means F4 include first and second deflectors f7 and f8 which are constituted by spaced electrode plates P and P', Q1 and Ql and Q2 and Q'z and do not, as in the embodiment of FIG. 5, include the additional electrode plates H and H and their associated insulators I and I. Too, in the embodiment of FIG. 8, the electrode plates Q2 and Q2 are connected as shown to a terminal TR rather than to the terminal TP as heretofore.

A voltage VR which is either substantially equal to or lower than the voltage V (FIGURE 5) is applied to the terminal TR from an equivalent power source VS which is similar to the power source VS. The power source VS is connected as shown across the terminals TP and TR to effect the static defiection of the respective electron beams BB and BR in convergent directions in both of the first defiector f7 and the second defiector f8. In this instance, conventional horizontal dynamic convergence voltage generating means may be understood to be incorporated in the equivalent power sources VS and VS.

With the system of FIG. 8, the voltage VQ and/ or the voltage VR are adjustable, through the adjustment of either one of the equivalent power sources VS and VS', to enable the correction of the position of the apparent deflection center of the deflection means F to a predetermined position with respect to the respective electron beams BB and BR. By the system of FIG. 8, it also becomes possible to correct the incident angles of the electron beams BR, BG and BB at the common spot with respect to the screen grid Gp. Thus, if the distance between the color phosphor screen S and the screen grid GP and/or the distance between the latter and the deflecting means F are somewhat deviated, it is nonetheless possible to compensate for the resultant misconvergence of the electron beams BR, BG and BB at the screen grid GP to insure that the said electron beams properly strike the respective color phosphor stripes SR, SQ and SB.

Suitable modification could, of course, be made in the embodiment of FIG. 8 to achieve therein convergent, rather than divergent, defiection of the respective electron beams BB and BR in the first defiector f8 in the manner described hereinabove with regard to the embodiments of FIGS. 3 and 5. Too, and with regard to the embodiment of FIG. 6, it is to be understood that the respective current flow directions of the deflecting currents supplied to the electromagnets C1 and C1 of the first defiector f5 may be arranged to be opposite to those described above to thus provide for the convergent deliection of the said electron means in both of the first deflector f5 and the second defiector f6 of the embodiment of FIG. 6.

Further, it is to be understood that three electrically independent cathodes may, in each of the disclosed embodiments of this invention, be substituted for the single cathode K. In addition, although the first grid G1 of the electron .gun has in each instance been described as being formed by electrically independent grid members G1R, GlG, and G1R, it is also lto be understood that a single grid member comprising three apertures may be readily substituted therefor. Similarly, it is believed apparent that the herein disclosed embodiments of this invention would all be equally applicable lto a color picture tube system utilizing a conventional shadow-mask type color picture tube wherein the screen grid G were replaced by a shadow-mask. Also, although disclosed herein as applied to a three-beam color picture tube, it is to be understood equally applicable, with suitable modification, to use in conjunction with color picture tubes wherein two electron beams, or four or more electron beams, are utilized in the reproduction of color pictures.

It will be apparent that many modifications and variations other than those described hereinabove, may be effected in the disclosed embodiments of this invention without departing from the spirit and scope of the latter as defined by the appended claims.

What is claimed is:

1. In a color picture tube system which includes a color screen, an electron gun means spaced therefrom, means for directing a plurality of electron beams toward said color screen, lens means for focussing said electron beams, and means for passing said electron beams through the optical center of said focussing lens means with one of said beams emerging therefrom along the optical axis of said focussing lens means and the other of said beams emerging therefrom along paths which are divergent thereto, the improvements comprising, electron beam deflecting means including first and second electron beam deflcctors which are arranged successively in the path of said electron beams from said electron gun means to said color screen, said electron beam defiecting means being operable to enable the undeflected passage therethrough of said one beam while defiecting said other beams so that all of said electron beams may be converged at a common spot corresponding to a color picture element on said color screen.

2. In a colo-r picture tube system as in claim I wherein, said first electron beam deflector defiects said other electron beams in divergent manner, and said second electron beam deflector deflects said other electron beams in convergent manner to achieve said electron beam convergence at said common spot.

3. In a color picture tube system as in claim 1 wherein, said first electron beam deflector deflects said other electron beams in convergent manner, and said second electron beam deflector also defiects said other electron beams in convergent manner to thereby effect said electron beam convergence at said common spot.

4. In a color picture tube system as in claim 1 wherein, each of said first and second electron beam deflectors comprises means for applying an electric field to said other electron beams to thus electrostatically defiect said other electron beams.

5. In a color picture tube system as in claim 1 wherein, each of said first and second electron beam deflectors comprises means for applying a magnetic field to said other electron beams whereby the latter are magnetically deflected.

6. In a color picture tube system as in claim 2 wherein, each of said first and second electron beam deflectors f includes means for applying an electric field to said other electron beams whereby, said other electron beams are electrostatically deflected.

7. In a color picture tube system as in claim 2 wherein, each of said first and second electron beam defiectors includes means for applying a magnetic field to said other electron beams whereby said other electron beams are magnetically defiected.

8. In a color picture tube system as in claim 3 wherein, each of said first and second electron beam defiectors includes means for applying an electric field to said other electron beams whereby, said other electron beams are electrostatically deflected.

9. In a color picture tube system as in claim 6 wherein, said first and second electron beam deflectors comprise an adjustable deflecting voltage source connected thereto whereby, the extent of said other electron beam deflections may be controlled by adjustment of said adjustable detiecting voltage source.

10. In a color picture tube system as in claim 7 wherein, said first and second electron beam deflectors comprise an adjustable deecting current source connected thereto whereby, the extent of said other electron beam deections may be adjusted by adjustment of said adjustable detlecting current source.

11. In a color picture tube system as in claim 8 wherein, said first and second electron beam deectors comprise an adjustable detlecting voltage source connected thereto whereby, the extent of said electrostatic deflection of said other electron beams may be adjusted by adjustment of said adjustable deecting voltage source.

12. In a color picture tube system as in claim 8 wherein, said rst electron beam deector comprises an adjustable deflecting voltage source connected thereto, and said second electron beam deflector comprises another adjustable voltage source connected thereto whereby, the respective electrostatic deilections of said other electron beams may be adjusted by adjustment of said adjustable voltage source and said another adjustable voltage source, respectively.

References Cited UNITED STATES PATENTS 2,197,523 4/1940 Gabor 315-17 2,679,614 5/1954 Friend 315-13 2,922,073 1/ 1960 Oestreicher.

RODNEY D. BENNETT, JR., Primary Examiner M. F. HUBLER, Assistant Examiner U.S. Cl. XR. 3 13-77

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