US3575625A

US3575625A - Color tube with convergence electrode mounting and connecting structure

Info

Publication number: US3575625A
Application number: US813938A
Authority: US
Inventors: Senri Miyaoka
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1968-04-13
Filing date: 1969-04-07
Publication date: 1971-04-20
Anticipated expiration: 1988-04-20
Also published as: FR2044422A5; NL162784B; DE1918877B2; US3579008A; FR2006209A1; GB1221043A; DE1922229B2; DE1918877A1; NL162786B; GB1216436A; NL162786C; NL6906914A; NL162784C; NL6905716A; DE1922229A1

Abstract

In a single-gun, plural-beam color picture tube in which two beams emerge from a focusing lens along paths that diverge with respect to a central beam emerging along the optical axis of the lens by which all of the beams are focused on the color screen, and the divergent beams are deflected to converge with the central beam by passage through respective electrical fields established between first spaced plates, at opposite sides of the central beam path, and second plates spaced outwardly from the first plates; such plates are disposed closely adjacent to the main deflection yoke by which the beams are made to scan the screen so that the length of the tube can be minimized, and the misconvergence of the beams that would result from a current flow induced in a closed conductive loop that includes the first plates by flux change of the magnetic field of the main deflection yoke is avoided by mounting the first plates in a cantilevered manner at one end and by omitting any conductive connections between the remainder of such plates so that a conductive loop does not exist for the induced current.

Description

United States Patent [72] Inventor Senri Miyaoka 2,921,228 1/1960 Famsworth 3 l3/78X Kanagawa-ken, Japan 3,358,172 12/1967 Lewis '313/80 [21] Appl. No. 813,938 3,448,316 6/1969 Yoshida et al. 313/70CX [22] 1969 Primary Examiner-Robert Segal [45] Patented Apr. 20, 1971 [73] Assign Sony Commfion ArtorneysAlbert Johnston, Robert E. lsner, Lewrs H.

shimgawbku, Tokyo, Japan Eslmger and Alvin Srnderbrand [32] Priority Apr. 13, 1968 [33] Japan 43/24621 ABSTRACT: In a single-gun, plural-beam color picture tube [5 in two beams emerge from a focusing along paths ELECTRODE MOUNTING AND CONNECTING that diverge with respect to a central beam emerging along the optical axls of the lens by WhlCh all of the beams are focused STRUCTURE on the color screen, and the divergent beams are deflected to 5 Claims, 5 Drawing Figs.

converge with the central beam by passage through respective electrical fields established between first spaced plates, at opposite sides of the central beam path, and second plates Int. U. paced outwardly from the first plates; such plates are 29/82 29/74 disposed closely adjacent to the main deflection yoke by [50] FleltlOf Search ..3l3/70 (C), hich the beams are made to scan the screen so that the 73, 80 length of the tube can be minimized, and the misconvergence of the beams that would result from a current flow induced in [56] References Clted. a closed conductive loop that includes the first plates by flux UNITED STATES PATENTS change of the magnetic field of the main deflection yoke is 2,163,233 6/1939 Brown 313/78 avoided by mounting the first plates in a cantilevered manner 2,168,892 8/1939 Zworykin 313/80 at one end and by omitting any conductive connections 2,170,944 8/1939 Glass et al.... 313/78X between the remainder of such plates so that a conductive 2,459,724 1/1949 Selgin 313/78X loop does not exist for the induced current.

l5 1 l I l I /8 e 1 4 P I l F4- 24 L2 23)) 25' PATENTEU AFR20 19m INVENTOR. SENR! MI YAOKA ATTORNEY EG LGR TUBE Wll'llill CONVERGENCE ELECTRODE MOUNTING AND CONNECTHNG STRUCTURE This invention relates generally to plural-beam color picture tubes, and particularly to tubes of that type in which the plural beams are passed through the optical center of a common electron lens by which the beams are focused on the color phosphor screen so as to eliminate coma and spherical aberration by reason of the lens.

in plural-beam color picture tubes of the described type, for example, in the single-gun tube as specifically disclosed in the copending application Ser. No. 697,414, filed Jan. 12, 1968 now US. Pat. No. 3,448,316 and having a common assignec herewith, three laterally spaced electron beams are emitted or originated by a beam generating or cathode assembly and directed in a common substantially horizontal or vertical plane with the central beam coinciding with the optical axis of the single electron focusing lens and the two outer beams being converged to cross the central beam at the optical center of the lens and thus emerge from the latter along paths that are divergent from the optical axis. Arranged between the focusing lens and the color screen is an electrostatic convergence deflecting means by which the beams divergent from the optical axis are deflected substantially in the plane of origination thereof for causing all of the beams to converge at a common location on a beam selecting means, such as an aperture grill, and to pass therethrough for impingement on respective color phosphors of a color screen. Further, between the focusing lens and the beam selecting means, the beams are acted upon by the magnetic fields resulting from the application of horizontal and vertical sweep signals to a main deflection yoke, whereby the beams are made to scanthe screen in the desired raster. The convergence deflecting means of the foregoing color picture tube conveniently comprises a first paid of spaced plates between which the central beam is passed, and a second pair of plates spaced outwardly from the first plates so that the divergent beams are passed between the first and second plates to be deflected for convergence by electrical fields provided therebetween when one voltage is applied to both first plates and a different voltage is applied to both second plates.

if the above convergence deflecting plates are to be remote from the magnetic fields of the main deflection yoke, the length of the neck of the tube envelope is undesirably increased and requires a corresponding increase in the depth of the television receiver cabinet to accommodate the tube. 0n the other hand, if the neck portion of the tube is shortened, which requires that the convergence deflection plates extend closely adjacent to the main deflection yoke, and if the first plates are interconnected to constitute a closed conductive path, a magnetic field of the main deflection yoke induces a current flow in the closed path constituted by the interconnected first plates, and such current flow produces a magnetic field that deflects the central beam away from accurate convergence with the other two beams.

Accordingly, it is an object of this invention to provide a plural-beam color picture tube of the described type in which the convergence deflection plates are closely adjacent to, or even axially overlapped with respect to the main deflection yoke so as to minimize the necessary length of the neck portion of the tube envelope, and further in which any misconvergence that would result from the proximity of the convergence deflection plates to the main deflection yoke is avoided.

ln accordance with an aspect of this invention, the misconvergence that would result from the proximity of the convergence deflection plates to the main deflection yoke is avoided by mounting the first convergence deflection plates, that is, the plates between which the central beam passes, so that the latter do not constitute parts of a closed conductive loop or path through which an induced current could be made to flow by a magnetic field of the main deflection yoke.

The above, and other objects, features and advantages of this invention, will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawing, in which:

FIG. 1 is a schematic sectional view in a horizontal plane passing through the axis of a single-gun, plural-beam color picture tube of the type to which this invention is preferably applied;

FIG. 2 is a fragmentary sectional view taken in the same plane as FIG. 1, and which shows the structural arrangement of a portion of such tube in order to reduce the length of the neck portion of the tube envelope;

H6. 3 is a transverse sectional view taken along the line 3-3 onFlG. 2; and

H08. 4 and 5 are perspective views showing the arrangements of the convergence deflection plates in a tube as shown on FIGS. 2 and 3 in order to avoid misconvergence in accordance with two respective embodiments of this invention.

Referring to the drawings in detail, and initially to FlG. 1 thereof, it will be seen that a single-gun, plural-beam color picture tube 10 of the type to which this invention may be applied comprises a glass envelope (not shown) having a neck and a cone extending from the neck to a color screen S provided with the usual arrays of color phosphors S 5 and S and with an apertured beam selecting grill or shadow mask G,.. Disposed within the neck is a single electron gun A having cathodes K K and K each of which is constituted by a beam-generating source with the respective beam-generating surfaces thereof disposed as shown in a plane which is substantially perpendicular to the axis of the electron gun. The beam-generating surfaces are arranged in a straight line so that the respective beams B,,, B and B emitted therefrom are directed in a substantially horizontal or other common plane containing the axis of the gun, with the central beam B),- being coincident with such axis. A first grid G, is spaced from the beam-generating surfaces of cathodes K K and K and has apertures g,,,, g,,;, and g, formed therein in alignment with the respective cathode beam-generating surfaces. A common grid G is spaced from the first grid G, and has apertures g g and g formed therein in alignment with the respective apertures of the first grid G,. Successively arranged in the axial direction away from the common grid G are openended,

' tubular grids or electrodes G,,, G,, and G respectively, with cathodes K,,, K and K grids G, and G and electrodes G,,, G,, and G being maintained in the depicted, assembled positions thereof, bysuitable, nonillustrated support means of an insulating material.

For operation of the electron gun of FIG. 1 appropriate voltages are applied to the grids G, and G and the electrodes G,, G,, and G Thus, for example, a voltage of 0 to minus 400v. is applied to the grid G,, a voltage of 0 to 500v. is applied to the grid 6,, a voltage of 13 to 20kv. is applied to the electrodes G and G and a voltage of 0 to 400v. is applied to the electrode G,, with all of these voltages being based upon the cathode voltage as a reference. As a result, the voltage distributions between the respective electrodes and cathodes, and the respective lengths and diameters thereof, may be substantially identical with those of a unipotential single beam-type electron gun which is constituted by a single cathode and first and second, single-apertured grids.

With the applied voltage distribution as described hereinabove, an electron lens field will be established between grid G and the electrode G to form an auxiliary lens L' as indicated in dashed lines, and an electron lens field will be established around the axis of electrode G,,, by the electrodes G,,, G and G to form a main focusing lens L, again as indicated in dashed lines. In a typical use of electron gun A, bias voltages of l00v., 0v., 300v., 20KV. 200v. and 20v. may be applied respectively to the cathodes K,,, K and K the first and second grids G, and G and the electrodes G,,, G, and G Further included in the electron gun of FIG. 1 are electron beam convergence deflecting means F which comprise a first pair of shielding plates P and P disposed in the depicted spaced, relationship at opposite sides of the gun axis, and a second pair of axially extending, deflector plates Q and O which are disposed, as shown, in outwardly spaced, opposed relationship to shielding plates P and P' respectively. Although depicted as substantially straight, it is to be understood that the deflector plates Q and Q may, alternatively, be somewhat curved or outwardly bowed, as is well known in the art.

The shielding plates P and P are equally charged and disposed so that the central electron beam B will pass substantially undeflected between the shielding plates P and P, while the deflector plates and Q have negative charges with respect to the plates P and P so that respective electron beams B and B will be convergently deflected as shown by the respective passages thereof between the plates P and Q and the plates P and Q. More specifically, a voltage V, which is equal to the voltage applied to the electrode G may be applied to both shielding plates P and P, and a voltage V which is some 200 to 300v. lower than the voltage V,., may be applied to the respective deflector plates Q and Q to result in the respective shielding plates P and P being at the same potential, and to result in the application of a deflecting voltage difference or convergence deflecting voltages between plates P and Q and plates P and Q and it is, of course, this convergence deflecting voltage V which will produce electric fields to impart the requisite convergent deflection to electron beams B and B In operation, the electron beams B B and B which emanate from the beam generating surfaces of the cathodes K K and K will pass through the respective grid apertures g g and g,,,, to be intensity modulated with what may be termed the red, green and blue intensity modulation signals applied between the said cathodes and the first grid G,. The respective electron beams will then pass through the common auxiliary lens L to cross each other at the center of the main lens L and to emerge from the latter with beams B and B diverging from beam B Thereafter, the central electron beam 8 will pass substantially undeflected between shielding plates P and P since the latter are at the same potential. Passage of the electron beams 8,, between the plates P and Q and of the electron beam B between the plates P and Q will, however, result in the convergent deflections thereof as a result of the convergence deflecting voltage applied therebetween, and the system of FIG. 1 is intended to be so arranged that electron beams B B and B will desirably converge or cross each other at a common spot centered in an aperture of the beam selecting grill G, and then diverge therefrom to strike the respective color phosphors of a corresponding array thereof on screen S. More specifically, it may be noted that the color phosphor screen S is composed of a large plurality of sets or arrays of vertically extending red, green and blue phosphor stripes or dots S S and 8,, with each of the arrays or sets of color phosphors forming a color picture element. It will be understood that the common spot of beam convergence corresponds to one of the thusly formed color picture elements.

Electron beam scanning of the face of the color phosphor screen is effected by horizontal and vertical deflection yoke means indicated in broken lines at D and which receives horizontal and vertical sweep signals whereby a color picture will be provided on the color screen. Since, with this arrangement, the electron beams are each passed, for focusing through the center of the main lens L of electron gun A, the beam spots formed by impingement of the beams on the color phosphor screen S will be substantially free from the effects of coma and/or astigmatism of the main lens, whereby improved color picture resolution will be provided.

As shown on FIGS. 2 and 3, in a structural embodiment of the tube schematically illustrated on FIG. 1, the plates P and P were supported, at the sides of their ends closest to electrode G,,, by

angle members

12 and 13 secured to a flange 11 at the adjacent end of a tubular extension of electrode 0,, which is, in turn, supported within tube neck N by insulating discs 24 and having getter rings 22 and 23 suitably mounted therebetween. The forward ends of plates P and P were joined, at the sides of the latter, by conductive bracing members 21 extending therebetween. The voltage V,. is applied to plates P and P through a contact spring 18 extending from one of the bracing members 21 into engagement with a conductive coating 17 which is applied to the inner surface of the cone portion C of the tube envelope and extends into the adjacent neck portion thereof. The voltage V is applied to coating 17 by way of an anode button (not shown) provided in cone portion C, and is applied to electrode G from plates P and P by way of

angle members

12 and 13. From electrode G the voltage V may be applied to electrode G; by way of a suitable conductor (not shown). The voltage V may also be applied to aperture grill G as an anode voltage, by way of coating 17.

Posts or pins 14 extend outwardly from plates P and P and, at their outer ends, carry glass beads 15 by which plates Q and 2 are supported while being insulated with respect to plates P and P. The voltage V is applied to plate Q by a conducting lead 20 extending from a button 19 in neck N and the voltage V,, is applied to plate 0' by way of a conducting lead 16 extending between plates 0 and Q and being spaced from plates P and P.

In order to reduce the necessary length of neck N of the tube envelope, the convergence deflecting means F is located closely adjacent to the main deflection yoke D, and may even axially overlap the location of the latter as shown on FIG. 2. However, when convergence deflecting means F is thus located, it is disposed within the magnetic field with vertical lines of flux produced by main deflecting yoke D for causing the beams to horizontally scan the color screen. Since plate P, bracing members 21, plate P,

angle members

12,13 and electrode G form a closed conductive loop, the magnetic flux changes in such magnetic field of yoke D induce a current to flow in the closed loop, and the induced current, in turn, produces a magnetic field between plates P and P that acts on the central beam B in the direction opposed to the horizontal scanning movement of the beams. Since the other beams B and B are not acted upon by the magnetic field between plates P and P resulting from the induced current, at any instant during each horizontal scan the point at which beam B reaches the aperture grill G. will lag behind the point on the latter at which beams B and B converge, whereby misconvergence results.

In accordance with this invention, such misconvergence is avoided by mounting the plates P and P so that the latter will not constitute parts of a closed conductive loop in which a current can be induced to flow by a magnetic field of yoke D. Such closed conductive loop is avoided, in accordance with the invention, by electrically connecting plates P and P only at one end thereof.

For example, in the embodiment of this invention shown on FIG. 4, the ends of plates P and P closes to electrode G are mounted on flange 11 of the latter by

flanges

112 and 113 directed outwardly from such ends of the plates and having cutouts, as at 1130, through which beams 13,, and B may pass for entering between plates P and Q and plates P and Q. The opposite or forward ends of plates P and P may be free of each other (FIG. 5) or merely held in spaced relation by members 26 and 27 of an electrically insulating material. Thus, the forward ends of plates P and P are insulated from each other either by members 26 and 27 or by air.

In order to further brace the plates P and P and to mount the plates Q and Q with respect thereto, metal pins 114a and 11412 are welded, soldered or otherwise secured to opposite longitudinal edges of plate P to locations spaced apart along the latter, and metal pins 114'a and 114b are similarly secured to plate P' at locations that are opposed to pins 114a and 114b, respectively. The pins 114a and 11411, and the pins 114a and ll4'b extend perpendicular to the planes of the respective plates P and P and are of sufficient length, as shown, to extend between plates 0 and Q. At the ends of pins 114a and 114'a adjacent plate Q, such pins are anchored in an insulating member traversing the outer surface of plate 0 and being suitably secured thereto, and ends of pins 114]; and ll4'b are similarly anchored in an insulating member 15 traversing and being secured on the 'outer surface of plate 0. The opposite ends of pins 114a and l14'a and of pins 11417 and ll4'b are similarly anchored in insulating members 15 traversing and being secured on the outer surface of plate 0. Further, plates P and P' have cutouts or

notches

28 and 28, respectively, through which pins 114a and ll4'b and pins 114a and 1l4b respectively pass without contacting plates P and P'.

It will be apparent that the above described structure supports plates Q and Q in spaced relation to plates P and P, respectively, while being insulated from the latter. Further, such structure, maintains the spaced relation of plates P and P forwardly of the

flanges

12 and 13 for mounting an electrode flange 11, while avoiding the formation of a closed conductive loop that includes plates P and P and in which a current could be induced by the proximity of the convergence deflecting device F to the yoke D.

In the embodiments of FIGS. 4 and 5, the voltage V,. can be applied to plates P and P by a spring or springs (not shown) similar to the spring 18 of FIG. 2, which such plates P and P being electrically connected to each other only at one end by way of flanges ll, 12 and 13. Further, the voltage V can be applied to plate 0 in the manner described above in connection with FIG.- 2, and from plate 0 to plate Q by way of a conductor 116 which is spaced from plates P and P.

Although illustrative embodiments of the invention have been described in detail herein, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be made therein by one skilled in the art without departing from the scope or spirit of the invention.

lclaim:

1. A plural-beam color picture tube comprising a color screen having arrays of color phosphors, and beam selecting means with apertures corresponding to said arrays, beam generating means for directing a plurality of electron beams toward said color screen for impingement on respective phosphors of each array through the corresponding aperture,

between said lens means and said beam selecting means for deflecting said two beams emerging along said divergent paths so as to achieve convergence of all of said beams at an aperture of said beam selecting means, and magnetic yoke means also interposed between said lens means and said beam selecting means for producing a magnetic field by which said beams are simultaneously deflected to scan said screen; said convergence deflecting means including first plates which are spaced apart for the passage of said one beam therebetween, second plates spaced outwardly from said first plates so that each of said two beams passes between a first plate and a second plate and means to apply one voltage to said first plates and a different voltage to said second plates so that the voltage difference between said first plates and said second plates produces electrical fields therebetween for effecting said convergence, said convergence deflecting means being disposed closely adjacent to said magnetic yoke means so as to reduce the necessary length of the tube, said first plates being electrically connected to each other only at one end to avoid the provision of a closed conductive loop that includes said first plates andin which a current could be induced to flow by said magnetic field produced by said yoke means, and insulating members traversing said second plates and secured thereto at locations spaced therealong, conductive pins extending between said insulating members on one of said second plates and the correspondingly located insulating members on the other one of said second plates, each of said conductive pins being rigidly and electrically connected with only a respective one of said first plates.

2. A plural-beam color picture tube according to claim 1, in which insulating members extend between the other ends of said first plates to maintain the latter in spaced relation.

3. A plural-beam color picture tube according to claim 1, in

Y which the other ends of said first plates are free of each other and have an insulating air space therebetween.

4. A plural-beam color picture tube according to claim 1, in which said conductive pins extend past the opposite longitudinal edges of said first plates, said longitudinal edges have cutouts therein, and each of said pins connected with one of said first plates extends with clearance through a respective one of said cutouts in the other of said first plates.

5. A plural-beam color picture tube according to claim 1, in which said conductive pins are arranged in pairs extending past the opposite longitudinal edged of said first plates, with one pin of each of said pairs thereof being connected with one of said first plates and the other pin of the respective pair of pins being connected with the other of said first plates.

Claims

1. A plural-beam color picture tube comprising a color screen having arrays of color phosphors, and beam selecting means with apertures corresponding to said arrays, beam generating means for directing a plurality of electron beams toward said color screen for impingement on respective phosphors of each array through the corresponding aperture, lens means for focusing said electron beams on said color screen and having an optical center through which all of said beams are passed with one of said beams passing through said lens means along the optical axis of the latter and two of said beams being angled with respect to said optical axis to emerge from said lens means along paths divergent to said axis, electron beam convergence deflecting means interposed between said lens means and said beam selecting means for deflecting said two beams emerging along said divergent paths so as to achieve convergence of all of said beams at an aperture of said beam selecting means, and magnetic yoke means also interposed between said lens means and said beam selecting means for producing a magnetic field by which said beams are simultaneously deflected to scan said screen; said convergence deflecting means including first plates which are spaced apart for the passage of said one beam therebetween, second plates spaced outwardly from said first plates so that each of said two beams passes between a first plate anD a second plate and means to apply one voltage to said first plates and a different voltage to said second plates so that the voltage difference between said first plates and said second plates produces electrical fields therebetween for effecting said convergence, said convergence deflecting means being disposed closely adjacent to said magnetic yoke means so as to reduce the necessary length of the tube, said first plates being electrically connected to each other only at one end to avoid the provision of a closed conductive loop that includes said first plates and in which a current could be induced to flow by said magnetic field produced by said yoke means, and insulating members traversing said second plates and secured thereto at locations spaced therealong, conductive pins extending between said insulating members on one of said second plates and the correspondingly located insulating members on the other one of said second plates, each of said conductive pins being rigidly and electrically connected with only a respective one of said first plates.

3. A plural-beam color picture tube according to claim 1, in which the other ends of said first plates are free of each other and have an insulating air space therebetween.