US3912104A

US3912104A - Sheet glass color tube face panel with pleated skirt

Info

Publication number: US3912104A
Application number: US437097A
Authority: US
Inventors: James W Schwartz
Original assignee: Zenith Radio Corp
Current assignee: Zenith Electronics LLC
Priority date: 1972-02-16
Filing date: 1974-01-28
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

A color television picture tube panel is fabricated of relatively thin sheet glass formed to define a substantially rectangular faceplate area surrounded by an upstanding flange having a fluted configuration over portions of its periphery. The end surface of the flange defines a seal edge for forming a glass-to-glass seal with a funnel having a seal edge of sufficient area to bridge the maximum peak to trough dimensions of the fluted portions. Methods of manufacturing such a panel are also described.

Description

United States Patent 1 [111 3,912,104 Schwartz Oct. 14, 1975 [54] SHEET GLASS COLOR TUBE FACE PANEL 3,071,280 l/1963 Mayhew et a1. 220/21 A WITH PLEATED SKIRT 3,322,522 5/1967 Meiresonne 65/44 X 75 l w Sch G] i 1 3,490,636 l/1970 Nienhuis et al .1 178/7.8 X

t rt l 1 or James Z FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee: 3 chug", 770,097 3 1957 United Kingdom 65/107 [22] Filed: Jan. 28, 1974 Primary ExaminerWilliam 1. Price Assistant Examiner-Stephen Marcus [211 App! 437097 Attorney, Agent, or Firm.lohn H. Coult Related US. Application Data [62] Division of Ser. No. 226,880, Feb. 16, 1972, Pat. No. [57] ABSTRACT 3,825,413, A color television picture tube panel is fabricated of relatively thin sheet glass formed to define a substan- [52] US. Cl 220/2.l A; l78/7.82 i l y r c ngul r faceplate area surrounded by an up- [51] Int. CL HOlJ 5/02 n ing flange having a flu ed configuration over por- [58] Field of Search 178/7.8, 7.86, 7.81, 7.82; tions of its periphery. The end surface of the flange 220/2,1 A, 23 A, 2,] R, 2,3 R; 65/44, 107 defines a seal edge for forming a glass-to-glass seal with a funnel having a seal edge of sufficient area to [56] R fere Cit d bridge the maximum peak to trough dimensions of the UNITED STATES PATENTS fluted portions. Methods Of manufacturing SUCh 21 2,878,623 3/1959 Vincent 220/2.1 A panel are also descnbed' 2,969,162 1 1961 Stutske 220/2.1 A 4 Claims, 3 Drawing Figures Oct. 14, 1975 U.S. Patent SHEET GLASS COLOR TUBE FACE PANEL WITH PLEATED SKIRT RELATED APPLICATION This application is a division of application Ser. No. 226,880, filed Feb. 16, 1972, now U.S. Pat. No. 3,825,413, issued July 23, 1974, and assigned to the assignee of this application.

BACKGROUND OF THE INVENTION This invention relates in general to color television picture tubes and in particular to glass envelopes for color television picture tubes.

The necessity of forming a phosphor mosaic image screen on the inner surface of the picture tube faceplate, which is capable of producing light of three primary colors responsive to selective excitation, dictates utilization of picture tube envelopes which are separable. The picture tube envelope consists of a panel or front section and a funnel or back section. The panel typically has an upstanding flange or skirt, which is useful for strengthening the panel, holding fluids used in screening and manufacturing, providing a seal edge, and for supporting a shadowing electrode in predetermined relationship to the image screen. In conventional tri-gun picture tubes available today, the shadow mask support consists of a plurality of inwardly directed studs embedded in the panel skirt. The shadowing electrode is removable from the mounting studs since, during normal screening operations, it must be inserted and removed a number of times. The need for a separable panel portion, the requirement of supporting a relatively heavy shadowing electrode and the necessity of withstanding high processing temperatures has resulted in the panel being made of exceptionally thick glass. As a result, the glass envelope represents the major cost in manufacturing a color television picture tube. The heavy thick glass panel imposes other restrictions on manufacturing since the various heating cycles must be programmed (in both heating and cooling phases) to preclude excessive stress buildup. In practice, substantial time is required for the gradual heat up and cool down cycles. With a panel of thinner glass, the time required for heating cycles may be reduced and manufacturing economies effected.

SUMMARY OF THE INVENTION In accordance with the invention, the massiveness of the glass panel may be greatly reduced without degradation of its strength characteristics. This is achieved by making the panel with an upstanding partially fluted flange surrounding the faceplate area. The fluted portions are readily formed in the upstanding flange or skirt in a simplified panel manufacturing technique and provide desirable strengthening of the panel member. The resultant panel, while being lighter, retains the requisite resistance to deformation during high processing temperatures encountered in color tube manufactur- The seal edge or mating surface of the panel is formed by grinding or trimming, since it must be relatively flat for frit sealing with the funnel member. The seal edge, however, includes wavelike portions in the panel corners, which requires the seal edge of the funnel to be sufficiently large to bridge the maximum peak to trough dimensions of the flutes.

The fact that a panel configuration including fluted corners may be used in conjunction with an appropriate funnel allows the panel to be fabricated from sheet glass. Consequently, the fluted construction enables manufacturing economies as well as structural economies.

Accordingly, a principal object of this invention is to provide a panel for a color cathode ray tube requiring substantially less material than prior art panels.

A further object of this invention is to provide an economical panel for a color cathode ray tube characterized by fluted portions in the panel skirt.

Another object of this invention is to provide a panel for a color cathode ray tube which is manufactured from sheet glass material formed with fluted strengthening portions in the skirt.

Other objects and advantages of this invention will become apparent upon reading the following description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a glass envelope including a partially cutaway panel section constructed in accordance with the invention and a mating funnel section.

FIG. 2 represents an enlarged partial view of the inside of the panel of FIG. 1 taken along the lines 22.

FIG. 3 represents a partial enlarged view of the funnel of FIG. 1 taken along the lines 3-3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, a clear glass panel 10 includes an upstanding flange or skirt l1 terminating in a seal edge 13. Each corner of the panel includes a fluted portion 12 although such portions need not be restricted to the corners only. Mounted about the interior of the panel on the inside of the upstanding flange is a plurality of mounting studs 15 for supporting a conventional aper ture type shadow mask (not shown).

Spaced behind panel 10 is a funnel portion 16, including a large bell-shaped portion 17 and a cylindrical neck portion 18 terminating in a slightly flared portion 19. During a stage of manufacture, an electron gun assembly will be inserted into neck 18 and sealed therein. In the process, flange 19 will be cut off. Funnel 17 also includes-a seal edge 20 for mating engagement with corresponding seal edge 13 of panel 10. Seal edge 20 is flared in the corners as shown at 21 to accommodate the fluted portions of panel 10. Except that funnel 16 includes flared portions in the corners along the seal edge and that panel I0 is made of thinner glass and has fluted strengthening portions, the tube envelope is similar to those presently in use.

FIG. 2 shows a fluted portion of panel 10 in detail. The seal edge in the fluted portions generally define a sinewave having maximum amplitude at the diagonals of the panel and diminishing with increasing distance away from the diagonals. It is, of course, obvious that the glass frit used in the glass-to-glass sealing step of the final tube manufacture be capable of maintaining the requisite vacuum in the picture tube. Consequently, an enlarged sealing area is provided on the funnel seal edge to embrace the maximum peak to trough dimension of the fluted edge. The critical dimension is that included between 12a and 12b representing the minimum glass width required to bridge the flute excursions and make an airtight seal. Naturally, because of material and manufacturing tolerances, a larger seal edge than minimum is required, and as shown in FIG. 3, a practical size is one that extends over the full range of excursion of the flutes.

FIG. 3 is an enlarged view of the seal edge of the funnel in one corner with a dashed line representation of fluted portion 12 of the panel superimposed to pictorially show the above relationship of parts. The funnel to panel sealing operation may be readily performed by laying a bead of frit material on the panel seal edge following the fluted configuration. Alternatively, the frit seal may be made by laying a wide bead of frit along the funnel seal edge, the frit dimension being large enough to surround the fluted glass portion of the panel.

A color tube panel in accordance with the invention lends itself to different techniques of manufacture also. Practically, a sheet of glass material of required thickness may be sagged over a form which defines the interior surface of the desired picture tube panel. As the glass sags over the rectangular form, fluted portions or folds will develop in the corners. After the requisite degree of cooling, the seal edge is formed, preferably by cutting off unwanted material with a high pressure flame. (The seal edge may also be formed by a grinding operation.) Mounting studs 15 may be inserted either as shown in FIG. 2, by locally softening the glass in the upstanding flange and pushing the studs into position, or by the well-known technique of fritting. lt should be understood that the orientation and position of the mounting studs are determined by tool mechanisms (not shown) which are independent of minor irregularities in the upstanding flange.

The panel may also be readily vacuum formed or pressed into the appropriate configuration while in the moldable state. The end result of each of these techniques is an economically manufactured panel of requisite strength but much lighter construction.

The provision of the fluted portions at the corners of the panel is essential to attain sufflcient strength, especially to prevent warping ofthe glass during tube manufacture. In particular, after the mosaic phosphor screen has been deposited using a suitable apertured electrode for photoexposure any distortion of the panel will upset the critical relationship between the aperture mask and the phosphor screen.

For sealing purposes, however, it may be desirable to somewhat compress the fluted portions while still in the moldable state to reduce the maximum peak to trough dimension mentioned above. In that instance, the seal edge of the funnel need not be flared as much to provide proper sealing contact.

The funnel, as shown, includes flared portions in the corners providing the requisite larger seal edge for mating with the panel fluted portions. Alternatively, the funnel may have an outwardly directed ledge formed about its periphery for defining a large area seal edge.

What has been described is a novel construction for a color television picture tube envelope. It is recognized that numerous modifications and changes in the invention may be made without departing from the invention as set out in the claims.

I claim:

1. A color television picture tube envelope comprising a sheet glass panel having a seal edge and a mating funnel having a seal edge adapted to mate with the seal edge of the panel, said panel including a clear faceplate area circumscribed by an upstanding flange, at least portions of said flange having folds which extend axially to the panel seal edge and make sealing engagement with the funnel seal edge.

2. A color television picture tube envelope as set forth in claim 1 wherein the folds have a plurality of troughs and peaks, and wherein said funnel seal edge is of sufficient area in the region of said folds to bridge the maximum trough-to-peak dimension of said folds.

3. A color television picture tube envelope as set forth in claim 1 wherein said faceplate area is of generally rectangular shape, wherein the portions of said flange adjacent the sides of the rectangle are substantially flat, and wherein said folds are located in each of the corners of said flange.

4. A color television picture tube envelope as set forth in claim 3 wherein said funnel seal edge comprises an outwardly directed ledge formed in the large end of said funnel which is enlarged in the funnel corner regions such that the seal edge of the funnel is large enough to embrace the folds at the seal edge in the corners of the panel.