US2939981A

US2939981A - Grid frame support structures for cathode ray tubes

Info

Publication number: US2939981A
Application number: US719975A
Authority: US
Inventors: Kenneth A Hoagland
Original assignee: Paramount Pictures Corp
Current assignee: Paramount Pictures Corp
Priority date: 1958-03-07
Filing date: 1958-03-07
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

June 7, 1960 K. A. HOAGLAND GRID FRAME SUPPORT STRUCTURES FOR CATHODE RAY TUBES 3 Sheets-Sheet 1 Filed March 7, 1958 INVENTOR. KENNETH A. HOAGLAND BY 9,. 705;

A TTOPNE Y June 7, 1960 K. A. HOAGLAND 2,939,981

GRID FRAME SUPPORT STRUCTURES FOR CATHODEZ RAY TUBES Filed March '7, 1958 3 Sheets-Sheet 2 28 20 8 flllll '7 Fig. 6

INVENTOR. KENNETH A. HOAGLAND BY I QM 2&4

' A TTORNEYA June 7, 1960 K. A. HOAGLAND GRID FRAME SUPPORT STRUCTURES FOR CATHODE RAY TUBES 3 Sheets-Sheet 3 Filed March 7, 1958 r I r 1 1/ 1/ 1 Q Fig.4

INVENTOR. KENNETH A. HOAGLAND ATTORNEY United tates Patent 2,939,981 Patented June 7, 1960 GRID FRAm SUPPORT STRUCTURES FOR CATHODE RAY TUBES Kenneth A. Hoagland, West Milford, N.J., assignor to Paramount Pictures Corporation, New York, N.Y., a

corporation of New York Filed Mar. 7, 1958, Ser. No. 719,975 4 Ulaims. (Cl. 313-85) This invention relates in general to cathode-ray tubes of the type adapted to effect the reconstitution of polychrome images and is particularly directed to a grid support structure for such cathode-ray tubes for correct positiming of the grid relative to a striped phosphor screen or target electrode adjacent thereto and the transfer of tension from the grid structure to the glass bulb.

Cathode-ray tubes having a grid of essentially coplanar parallel wires located adjacent to a striped phosphor screen are now known in the art. Such a tube structure may in some cases serve to focus the beam electrons into a pattern of thin. lines nominally registered with discrete phos phor areas of the screen, as heretofore disclosed by Ernest 0. Lawrence as for instance by his copending United States patent application Serial No. 234,190, filed June 6, 1951, and his US. Patent No. 2,692,532 granted October 26, 1954.

One type of cathode-ray tube incorporating the above principle (which may be armed post-defiection-focusing PDF) is designed with a relatively large number of narrow component-color phosphor strips laid down in a predetermined sequence to form a screen, or target electrode. These phosphor strips luminesce, when impacted by the cathode-ray beam, in various component colors of the image to be synthesized. Generally the order in which the phosphor strips may be laid down are red, green, blue, green, red, green, blue, green,'etc. bearing in mind that the color of a phosphor as used herein refers to the color of the light emitted therefrom which is seen by an observer. An electrically-conductive coating overlies the phosphor strips and is produ ed in some preferred manner such as by zdimiinization.

A grid assembly is located adjacent to the phosphor screen and together with the support therefore, comprises the subject matter of the invention as contemplated herein. The grid is formed of a large number of linear conductors, extending in the same direction as the phosphor strips and lying in the path of electrons directed to the target electrode from the electron gun of the cathoderay tube. The wires of the grid assembly are electronoptically related to the phosphor strips so that, in this electron-optical sense, there is a wire aligned with each color group, or cell.

Between the actual or nominal plane of the wire grid assembly and the conductive coating on the phosphor strips a difference of potential is established. The proper magnitude and polarity of this potential difference produces a series of converging electrostatic fields for the beam electrons. These converging fields (which may be likened in an optical sense to cylindrical lenses) cause the beam electrons arriving at the wire grid from the electron gun of the tube to form a fine line structure on the phosphor target.

Color control in a cathode-ray tube having a grid assembly of the above nature (whether used for PDF or not) is brought about by a cylic change in the potentials the forces thus exerted vary at a frequency close to the natural resonant frequency of the wires, the latter will vibrate, resulting in an oscillation of the line pattern on the phosphor screen. It is very important to maintain proper spacing between the plane of the grid wires and the phosphor-coated surface of the target since this spacing is critical and must remain substantially unchanged during the operation of the cathode-ray tube. In the manufacture of such tubes care must be taken during tube manufacture to guard against lateral displacement or otherwise of the grid wires as such displacement will result in image distortion and color contamination. Because of the critical nature of the grid-surface spacing, it has been found generally necessary to exercise extreme care in the mounting of such grids within the cathode-ray tube in order to assure the accuracy thereof. This manner of operation does not lend itself readily to mass production techniques and the cost and time expended in the manufacture of such cathode-ray tubes becomes prohibitive.

The stresses produced by the horizontally spaced vertical grid wires of the grid assembly above described,

when in tension, upon the grid frame is a cumulative afapplied to selected wires of the grid, with the electrostatic fair and tends to deform the frame inward at the top and bottom of the tube, such deformation giving further rise to color contamination and image distortion which cannot be tolerated in the color tubes having the grid structure above explained.

To alleviate the effect of such stresses which give rise to color contamination and distortion the cathode-ray tube envelope and face plate are made to share part or all of the grid wire load through the medium of a plurality of tension supports rigidly mounted to the said bulb envelope and face plate and to which the grid frame is attached, the grid wires thereby transferring their tensile stresses to the support and ultimately to the bulb and face plate. To further distribute wire loading from grid frame to the glass panel elongated support-bar members are provided which are mounted to the frame to minimize unequal wire tensionin g thereof.

The grid tension supports serve not only to transfer a part or all of the grid wire load from the grid frame but also simultaneously therewith position the grid frame in its exact position relative to the phosphor strips on the face plate and envelope bulb so that distortion and contamination due to erroneous positioning thereof will be reduced to a It is therefore, one object of this invention to provide a grid support structure suitable for use in the cathoderay tubes to recreate color images produced from received signals transmitted under the standards of all presently proposed color television systems.

Another object of this invention is to provide tension supports for a grid structure capable of transferring to the cathode-ray tube face plate and bulb envelope a portion or all of the grid wire load away from the grid frame.

Another object of this invention is to provide tension supports for a grid support structure to precisely and easily position same with respect to the phosphor strip-pattern on the inside of the face plate to thereby conserve time, energy and expense in the fabrication of such tubes.

A still further object of this invention is to provide elongated tension supporting bar elements to equalize and minimize unequal tension distribution of the grid wires in the grid frame.

Other objects and advantages will be apparent from the following description of one preferred form of the invention and from the accompanying drawings in which:

Fig. 1 is a plain view in section of a cathode-ray tube illustrating the post-deflection-focusing (PDF) grid, frame and the support structure therefore according to the invention.

Fig. 2 shows the cathode-ray tube and (PDF) grid r and the support structure therefore through the line 2--2 of Fig. l. t 7

Fig.3 is a side-elevational view of the cathode-ray tube and thegrid support members therefore. i l V Fig. 41s a partial sectional ed vif'w through the line f Fi 2- Fig. 5 is" a partial sectionalized view of the grid frame and tube, and a support bar member for tension equal? ization between the grid frame and tube.

Fig. 6 shows a partial sectionaliz d view of the grid {tame and tube and a support bar member for tension equalization between the'grid frame and tube.

; Now referring to the drawings and particularly to- Figs. 1-.-3 there is shown a conveniently shaped cathode-- ray tube having an evacuated envelope 19 within which the electrode grid structure'is adapted to be mounted according to the present invention. The neck of the tube includes. such conventional elements as 7 an indirectly heated cathode. 11 which acts as thesource for a cat ode a seam n beam n ic t yt e. trace 2 n heat y he filame t .3- A i ce and partially sun' u b ing the cathode 11 is a control grid #Lor electrode, 14 suitably apertured to permit the passage of electrons which are subsequently formed into the beam 12. Surrounding the neck of the tube is a conventional focus coil- 14;: to focus the electron beam. The. control grid 14 functions'in the usual manner to modulate the emitted stream-of electrons in accordance with the potential applied thereto relative to the cathode 14. Also in the neck of the tube there is provided a first anode or grid #2 (identified by the reference numeral 15) to which suitable potentials may be applied so'as to result in an in-.

itial acceleration of electrons emitted from the cathode 11. "Adjacent to grid #2 there is' positioned a second anode or grid #3j(reference numeral 16) for applying an additional'acceleration to the electrons. V V 7 t Deflecting coils, 17 comprising a horizontal pair and a i vertical pair are provided for the usual'scanning purposes.

Qbviouslm'the terms horizontal and vertical are used hereiniin a descriptive sense only. 'Thus the electron enough to permit the frame to be relievedof those stresses which would otherwise have caused the'buckling .or'distortion threeof.

' The supporting members 28 are'di'sposed within the glass envelope at the frontal portion along the minor axis thereof so that the grid structure will be properly positioned within the envelope and especially with respect to the striped phosphor screen formed upon the'tube face according to the invention embodied herein. It may be into support member 28 causes stressesfrom the frame to, the glass panel or envelope to the, minor axis and within the channelgrooved portion thereof. The tightening of screw 30 the transfer of grid wire.

which the support member is'secured. 7 An additional pair of positioning members 28a are provided along the tube major axis and serve merely to prevent the. rotational movement of the grid frame aboutits minor axis. .Al-

though'for purposes of illustration positioning members 28a appear to be similar to support members 28, other ypes of positioning members can be used or utilized which would serve the same function. 7

Fig. .5 is an alterna 've method for supporting the grid frame '25 to the'glass envelope panel and shows more particularly the manner of distributing the tensile loading; of the frame due to the stressed gridwires over a larger portion of the grid frame to assure equal distrib'u-I tion of. the grid tensile stresses. on both sides of' the support member. This is done by means of utilizing a-dis beam 12is caused to scan a phosphor-coated target 19 'ontlie inner face of the cathode-ray tube '16 toproduce light which is visible through the end wall20 thereof.

Shown in Figs! 1- 3 is a grid frame structure generally designated'by the reference numeral 25 and comprising a substantially rectangular structural frame 26 having a tribution bar 3 0 adapted for mounting to the frame. The'distribution bar 30 is an elongated metal memberhaving 'a-plurality of sequentially spaced riser' portions 31' and'depressed portions'32 therebetweenfand'is seseriesioflhorizontally spaced coplanar vertical grid wires 27, and adapted to fit Within the envelope of the cathode andfcontinuous type channel member. 26 made from metal such as steel-alloy and the like3which is strong and ray tube 10. The frame 25 is made up of a singularcapable of withstanding high temperatures. A series of spaced 'coplanar'linear grid wires 27 ,(such' as stainless steel of 4. mil thickness). transverse to themajor axis of V the frame are fixedly mounted thereto andrigidly'supported thereby; Generally the grid wires 27 are tensionedin their longitudinal directions and allitheir tensile stresses transferred to the supporting frame. The result is the tendency of the frame to buckle or bend inwardly or to' become otherwise structurally distorted; To obviate this defecfthe tensile stresses of the grid wires are partially or allitransferredto'the glass envelope by permitting the frame to be supported thereby along the minor axis of the frame. The grid structure actually comprises a pair of separate insulated wire'grids each adapted to a be electrically connected to an external source of exciting;

potentials not shown.

.The frame 25 is supported along its minor axis by a pair ofsupporting members 28 which have one extremity thereof fixedly embedded in the glass envelope and'the other end securely attached to the frame. The tensile V stresses alongthe grid wires are transferredto the. sup-1 porting members andultiniately to the glass of the glass envelope, the transferred stresses to the glass being of V r the; order not suflicient to'cause the rupture thereofbut cured to .the frame' along its channeled'part. The frame lis then mounted to the glass envelope at the elongated metal member and secured. thereto by the supporting member 28 as previously described Thetightening of screw 33 to thepanel supporting member 28 permitsthe grid wire stresses to be transferred to the'panel, while simultaneously therewith, allows the stresses; along the frame to be distributed along-the elongated. bar member at its riser portions instead'of being'concentrated onlyv along the point where the screwr3 3 is' located.

.Fig. 6 shows .still another alternative method for sup-1' porting the grid frame 25 to the glass envelope and-is particularly directed .to the utilization of a pair of spaced support members 28 to which is secured by screws 34 t and 35 a support bar member 36.

The support bar 36 has intermediate its end parts a threaded hole 36a for receiving screw 37 which screw communicates with a bore 38 in bracket 39 welded; to

the frame; The frame 25 is thus supported by a pair of support pins 28 to distribute the stressed grid wire loading along the glass panelinstead of concentrating such tensile loading stresses to a givenpoint. V

i It is'to be understood that various modifications and changes can be made to the structure embodied herein without departing from the true intentjand purpose, of the invention illustrated in'the instant disclosure- Q Having described the invention the following is l me s.

1. Ina grid structure'suppor t design for incorporation f into a'cathode-ray tube having afaceplatewitha'pair of transverse axes'and a phosphor coated target elec-. trode upon. which images are reconstituted :in a plurality The bracket member 31 is rigidly] of colors, the combination comprising a grid structure having a support flame with tensionally stressed spaced grid Wires mounted thereon, at least a pair of support members secured to opposing ends on one of said axes in the face plate, and means, including a distribution bar secured to the support frame, disposed to symmetrically equalize the transfer of the tensile stresses of the said grid wires about the said axis from the grid frame to the face plate and the support members secured thereto.

2. In a grid structure support design for incorporation into a cathode-ray tube having a face plate with a pair of orthogonal axes symmetrical about their intersection and a phosphor coated target electrode upon which images are reconstituted in a plurality of colors the combination comprising a grid structure having a support frame with tensionally stressed spaced grid wires mounted thereon, at least a pair of support members mounted at opposite ends of one of said axes of symmetry in the face plate and means, including a distribution bar secured to the support frame, disposed to symmetrically equalize the transfer of the tensile stresses of the said grid wire about the said axis from the grid frame to the face plate and the support members secured thereto.

3. In a grid structure support design for incorporation into a cathode-ray tube having a face plate with a horizontal and vertical axis and a phosphor coated target electrode upon which images are reconstituted in a plurality of colors the combination comprising a grid structure having a support frame with tensionally stressed horizontally spaced coplanar vertical grid Wires mounted thereon, at least a pair of support members mounted at opposite ends of said axis in the face plate, and means, including an equalization bar member secured to the grid support frame, disposed to symmetrically equalize the transfer of the tensile stresses of the said grid Wires about the said axis from the grid frame to the face plate and the support members secured thereto.

4. in a grid structure design according to claim 1 wherein the distribution bar is an elongated member having a plurality of sequentially spaced riser portions.

References Cited in the file of this patent UNITED STATES PATENTS 2,722,623 Law Nov. 1, 1955 2,736,832 Zaphiropoulos Feb. 28, 1956 2,738,437 Lloyd Mar. 13, 1956 2,772,376 Cook Nov. 27, 1956 2,821,644 Henry Jan. 28, 1958 2,832,911 Van Velzer Apr. 29, 1958 2,842,696 Fischer-Colbrie July 8, 1958 2,856,552 Evans Oct. 14, 1958 2,906,904 Woughter Sept. 29, 1959