Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3772555 A
Publication typeGrant
Publication dateNov 13, 1973
Filing dateMar 30, 1972
Priority dateMar 30, 1972
Also published asDE2315353A1
Publication numberUS 3772555 A, US 3772555A, US-A-3772555, US3772555 A, US3772555A
InventorsMckee L, Roeber H
Original AssigneeGte Sylvania Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Color cathode ray tube of the shadow mask variety
US 3772555 A
Abstract
A shadow mask for a color cathode ray tube has a rectangular, relatively rigid, lightweight frame with an inwardly extending flange having attached thereto a circumferential side wall having a constant height. A foraminated relatively fragile face with a solid skirt portion having a portion thereof formed to provide a rectangular peripheral wall with four sides extending from the face is attached to the frame. Attachment is by means of welds between the peripheral skirt wall and the side wall of the frame. The four sides of the peripheral wall have a planar termination whereby the height of any one of the side walls is continuously variable when measured from adjacent points of the termination to the curved face. This construction provides a shadow mask having increased tolerance to permanent deformation caused by heat generated by impingement of an electron beam in a confined area for extended periods of time.
Images(2)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent [19.1

McKee et al.

[ Nov. 13, 1973 COLOR CATHODE RAY TUBE OF THE SHADOW MASK VARIETY [75] Inventors: Leffler H. McKee, Seneca Falls;

Henry W. Roeber, Waterloo, both of N.Y.

[73] Assignee: GTE Sylvania Incorporated, Seneca Falls, N.Y.

[22] Filed: Mar. 30, 1972 [21] Appl. No.: 239,516

[52] U.S. Cl. 313/85 S 3,454,813 7/1969 Lewinson 313/85 S X Primary ExaminerRoy Lake Assistant Examiner-James B. Mullins Att0rneyNorman J. OMalley et a1.

[57] ABSTRACT A shadow mask for a color cathode ray tube has a rectangular, relatively rigid, lightweight frame with an inwardly extending flange having attached thereto a circumferential side wall having a constant height. A foraminated relatively fragile face with a solid skirt portion having a portion thereof formed to provide a rectangular peripheral wall with four sides extending from the face is attached to the frame. Attachment is by means of welds between the peripheral skirt wall and the side wall of the frame. The four sides of the peripheral wall have a planar termination whereby the height of any one of the side walls isvcontinuously variable when measured from adjacent points of the termination to the curved face. This construction provides a shadow mask having increased tolerance to permanent deformation caused by heat generated by impingement of an electron beam in a confined area for extended periods of time.

3 Claims, 5 Drawing Figures mmnnnuv 13 ms 3.772.555

sum 10F 2 ji g. 5'

PRIOR ART COLOR CATHODE RAY TUBE OF THE SHADOW MASK VARIETY BACKGROUND OF THE INVENTION This invention relates to color cathode ray tubes of the shadow mask variety and more specifically to a rectangular shadow mask for use in such tubes. Color tubes of the type delineated above are in common usage and generally comprise a faceplate portion of glass having a patterned phosphor screen thereon and a plurality of electron guns for emitting streams of electrons which impinge on the patterned phosphors to cause selective color illumination. To aid in color selection and to define the beams a shadow mask is positioned between the phosphor screen and'the electron guns. This mask comprises a foraminated portion whose apertures are specifically aligned with the patterned phosphors on the screen. Such construction is well known. It has long been a desire to provide a frameless mask in this type of tube. Such a proposal was described in US. Pat. No. 2,690,518 and much later in U.S. Pat. No. 3,479,546. Both of these patents related to shadow masks which did not utilize a frame. However, neither of these various embodiments has ever been practically successful. Nevertheless, disadvantages continue to exist when a relatively heavy frame is utilized to support the very fragile foraminous mask. These disadvantages are that the heavy frame, of course, adds considerable weight to the tube and further acts as a heat sink during fabrication of the tube and during operation thereof. More particularly, one of the disadvantages of the heavy frame occurs during required drop testing of finished color television receivers. When such receivers are drop tested it has been found that a mask with a heavy frame is liable to pitch forward with such velocity that the welds which affix the supporting springs to the frame are broken. Furthermore, when such receivers pass the drop tests, problems occur during operation of the tube if, for example, a peculiar pattern is generated on the tube which requires that the full energy of all three electron beams be directed at a selected or confined area of the mask for extended periods of time. When this occurs, the fragile mask is very apt to buckle and become permanently distorted. This is due, primarily, to the difference in thermal expansion between the mask area and the heavy frame. It has been proposed that the frameless mask type of construction would avoid this problem; however, as has been stated above, such frameless masks inherently have other problems such as lack of sufficient rigidity and difficulty in manufacture.

OBJECTS AND SUMMARY OF THE INVENTION Therefore, it is an object of this invention to obviate the disadvantages of the prior art.

It is yet another object of the invention to provide a framed shadow mask which does not have the disadvantages of the prior art.

It is yet another object of the invention to provide a shadow mask that is economical to manufacture.

It is still another object of the invention to specifically provide a shadow mask that has increased tolerance to permanent deformation caused by heat generated by impingement of an electron beam in a confined area thereof for extended periods of time.

These objects are accomplished in one aspect of the invention by the provision of a shadow mask which has a relatively rigid light weight frame of substantially rectangular configuration and which is formed to provide an inwardly extending flange having an attached side wall thereabout, which side wall has a constant height. At least three areas of indentation can be formed in the side wall, one each being formed in the short sides and one in the long side of the frame. Support springs of known design and configuration are attached to the frame within the provided indentations. A relatively fragile, curved, foraminated face is provided which has a solid or imperforate skirt surrounding the face. A portion of the skirt is formed to provide a rectangular peripheral upstanding wall having four sides extending from the face and joined at the comers thereof. The four sides of the upstanding wall have a planar termination whereby the height of any one of the side walls is continuously variable when measured from adjacent points of the termination to the curved face. The peripheral wall of this foraminated face fits over the outside of the frame side wall and is attached thereto by a plurality of welds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a prior type color cathode ray tube;

FIG. 2 is an exploded perspective view of a later type of prior art shadow mask;

FIG. 3 is an exploded perspective view of a shadow mask incorporating the improvements of this invention;

FIG. 4 is a perspective detail of a spring mounting arrangement; and

FIG. 5 is an elevational view of an assembled mask and frame of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, capabilities and advantages thereof, reference is made to the following disclosure and appended claims in conjunction with the above-described drawings.

Referring now to the drawings with greater particularity, there is shown in FIG. 1 a shadow mask 10 comprising a circular frame 12 and a foraminated face 14. The face 14 has a peripheral circumferential wall 16 having a constant height which engages an upstanding wall 18 on the frame 12. This circular structure was the basic tube for many years until replaced by the rectangular variety now in'use.

An early variety of rectangular shadow mask 20 is shown in FIG. 2. Until the present invention, this construction was standard throughout the industry. Herein, the mask 20 comprises a rectangular frame 22 and a foraminated face 24. The frame in this instance has upstanding walls 25, the terminal portions 26 of which are curved to conform to the configuration of foraminated face 24. The face 24 has an upstanding wall 28 which, again, is of constant height. In assembly the face 24 and side walls 28 are fitted over the side walls 25 of frame 22 and are affixed thereto as by a plurality of welds. It will be seen in this structure, as in the structure of FIG. 1, that effectively the side walls of the frame act as the side walls of the face portion. That is, they provide a very rigid structure with the face portion being restricted in its ability to expand or contract because of the severe attachment of the peripheral wall of the face with the side walls of the frame. It is this restriction of movement which led to the buckling problems of the prior art structures.

Referring now to FIG. 3, it will be seen therein how the disadvantages of the prior art are obviated. There is here provided a shadow mask 30 having a frame 32, of substantially rectangular configuration, which is relatively rigid yet of light weight and a foraminated face 33. The frame 32 has an inwardly projecting flange 34 which has attached thereto a circumferential side wall 36 having a constant height. Elongated indentations 38 are provided in the side wall, generally three in number, with two being oppositely positioned in the short sides of the frame and one in the long side. Support springs for releasably holding the mask within the tube are affixed in these areas as will be explained hereinafter.

The foraminated face 33 is relatively fragile and is formed with a curved surface 40 surrounded by a solid skirt 42. A portion of skirt 42 is formed to provide a rectangular, peripheral, upstanding wall 44 having four sides extending from the face 33 and joined at the corners thereof. The four sides of the wall 44 have a planar termination 46 remote from the foraminated face 33. This construction provides for walls whose height is continuously variable when measured from adjacent points of the termination 46 to the curved face 33. Since the face is symmetrically curved about a centerline 47 (see FIG. it is obvious that the height variation discussed above occurs when both measuring points are on the same side of the centerline.

Before assembling the foraminated face 33 to frame 32, a plurality of leaf springs 48 are attached to the side wall 36 of frame 32 within indentations 38, as by welding. These indentations 38 have a depth substantially corresponding to the thickness of the springs; however, this relationship is exaggerated in FIG. 4 for clarity. The springs 48 have a flat area 50 which is in contact with the frame and have an outwardly angled area 52 which extends away from the frame. The distal ends 54 of springs 48 are provided with apertures 56 as is conventional in the art.

The sides 44 of face 33 fit over the side wall 36 of frame 32 and are provided with slots 58 to encompass the attached portions of springs 48. Thus, the slots have an overlying edge 60 which lies on top of attached flat area 50 and an underlying edge 62 which lies under the angled area 52. The edges of the slots 58 can be provided with an angled entry to facilitate assembly. A detail of the spring-mask assembly can be seen in FIG. 4.

The attachment of sides 44 to side 36 of frame 32 is accomplished by a plurality of welds 64 substantially equally spaced about the periphery of the mask. Further, the welds 64 are substantially the height above the flange 34 of frame 32, a definite advantage in manufacture.

If necessary, the two edges of slots 58 can be welded also. In such an instance, edge 60 is usually welded to flat area 50 of spring 48 and edge 62 is welded directly to frame wall 36. Further, it may be necessary that the latter two welds not be aligned with welds 64.

It will be seen from the above that a shadow mask constructed in accordance with the teachings contained herein provides definite advantages over the prior art structures.

The foraminated face with the planar termination of its side walls is stronger and easier to handle in assembly than its predecessor, which, before attachment to a frame, could only support itself on four corners (See FIG. 2). The novel frame provides sufficient rigidity yet is much lighter in weight than those of the prior art.

Primarily, however, is the operational improvement derived from the constant height of the frame wall and the variable height of the face wall. The greater flexibility of this construction provides for freer expansion and contraction of the mask not only in operation but also during processing and reduces the buckling problem to the point where it is practically nonexistant.

While there has been shown what is at present considered to be the preferred embodiment of the invention, it will be apparant to those of ordinary skill in the art that various changes can be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

l. A shadow mask for a color cathode ray tube, said shadow mask having increased tolerance to permanent deformation caused by heat generated by impingement of an electron beam in a confined area for extended period of time, and comprising: a relatively rigid light weight frame of substantially rectangular configuration being formed to provide an inwardly extending flange having an attached side wall thereabout having a constant height; at least three areas of indentations formed in said side wall, one each being formed in the short sides and one in the long side of said frame; and a relatively fragile portion having a curved foraminated face and a solid skirt surrounding said face, a portion of said skirt being formed to provide a rectangular, peripheral, upstanding wall having four sides extending from said face and joined at the corners thereof, said four sides of said wall having a planar termination whereby the height of any one of said side walls is continuously variable when measured from adjacent points of said termination to said curved face, said peripheral wall of said foraminated face fitting over the outside of said frame side wall and being attached thereto by a plurality of welds spaced thereabout; each of said indentations having a leaf spring attached thereto, said springs having a flat area in contact with said indentations and having outwardly angled areas, said peripheral upstanding wall having slots in at least three of said sides corresponding to said indentations and said slots being positioned so that one edge of each of said slots lies on said flat area of said spring and the other edge of said slots lies between said springs and said indentations.

2. The shadow mask of claim 1 wherein said edge of said slot lying on said spring is welded thereto and said edge of said slot lying between said spring and said indentation is welded to said frame.

3. The shadow mask of claim 2 wherein the remainder of the welds attaching said peripheral wall of said foraminated face to said frame are substantially equidistantly spaced from the jointure of said frame side wall and said frame flange.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3349272 *Nov 14, 1966Oct 24, 1967Philips CorpColor television tube with shadow mask provided with electron shielding plate coated with heat radiating material
US3449612 *Apr 24, 1968Jun 10, 1969Sylvania Electric ProdColor cathode ray tube having shadow mask frame formed to accommodate a support system
US3454813 *Sep 12, 1968Jul 8, 1969Admiral CorpMask-frame captivator
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3872345 *Oct 23, 1973Mar 18, 1975Hitachi LtdColour picture tubes
US4308485 *Mar 8, 1979Dec 29, 1981Videocolor, S. A.Shadow mask support in a color cathode ray tube
US4327307 *Mar 19, 1979Apr 27, 1982North American Philips Consumer Electronics Corp.Shadow mask for color cathode ray tube
US4565945 *May 11, 1983Jan 21, 1986North American Philips Consumer Electronics Corp.Deflection limiting means for CRT mask support means
US4645968 *May 27, 1986Feb 24, 1987Rca CorporationVibration control of color picture tube shadow mask
US5218265 *Feb 20, 1992Jun 8, 1993Nokia (Deutschland) GmbhCombined mask-frame with double spot welds
US5932957 *Apr 18, 1997Aug 3, 1999Thomson Consumer Electronics, Inc.Cathode-ray tube having detentioning rod assembly for a tension mask frame
US6278232Jan 27, 2000Aug 21, 2001Hitachi, Ltd.Color cathode ray tube
US6307310Sep 17, 1996Oct 23, 2001Hitachi, Ltd.Color cathode-ray tube
US6396203 *Jul 16, 1998May 28, 2002Nec CorporationColor shadow mask assembly with increased resistance to heat and vibration
US6483233 *Nov 12, 1999Nov 19, 2002Nec CorporationColor cathode-ray tube with expanded effective display area
US6518695 *Sep 21, 1999Feb 11, 2003Samsung Sdi Co., Ltd.Mask-frame assembly for cathode ray tube
US6518696Apr 19, 2001Feb 11, 2003Hitachi, Ltd.Color cathode ray tube with shadow mask and mask frame having round corners
US6833660Feb 27, 2003Dec 21, 2004Lg. Philips Displays Korea Co., Ltd.Cathode ray tube
US8210489 *Mar 9, 2010Jul 3, 2012Ricoh Company, LimitedFrame that supports a housing
DE3919674A1 *Jun 16, 1989Dec 20, 1990Nokia UnterhaltungselektronikMasken-rahmen-kombination fuer eine farbbildroehre
EP0004245A1 *Mar 9, 1979Sep 19, 1979VideocolorShadow-mask tube for colour television
EP1069592A2 *Jul 12, 2000Jan 17, 2001VIDEOCOLOR S.p.A.Cathode ray tube having a multifunction frame/mask support
EP1369893A1 *Feb 18, 2003Dec 10, 2003LG. Philips Displays Korea Co., Ltd.Shadow mask for cathode ray tube
WO1998048438A1 *Apr 1, 1998Oct 29, 1998Thomson Consumer ElectronicsColor crt and method of operating
Classifications
U.S. Classification313/404, 313/407
International ClassificationH01J29/07
Cooperative ClassificationH01J29/07, H01J2229/0772, H01J2229/0722
European ClassificationH01J29/07
Legal Events
DateCodeEventDescription
Aug 24, 1981AS99Other assignments
Free format text: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP. 100 EAST 42ND STREET, NEW YORK * GTE PRODUCTS CORPORATION A DE CORP. : 19810708 OTHER CASES: NONE; ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATE
Aug 24, 1981ASAssignment
Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.
Free format text: ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981.;ASSIGNOR:GTE PRODUCTS CORPORATION A DE CORP.;REEL/FRAME:003992/0284
Effective date: 19810708
Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.,