US3038096A

US3038096A - Color television tube

Info

Publication number: US3038096A
Application number: US566921A
Authority: US
Inventors: William J Knochel; James A Hall
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1956-02-21
Filing date: 1956-02-21
Publication date: 1962-06-05
Anticipated expiration: 1979-06-05

Description

June 5, 1962 w. J. KNOCHEL ETAL 3,038,096

COLOR TELEVISION TUBE Filed Feb. 21, 1956 2 SheetsSheet 1 |NVENT0RS WiHiom J. Knochel 8 WITNESSES W I 7 BY James A. Hall.

ATTORNEY June 5, 1962 w. J. KNOCHEL ETAL 3,038,096

COLOR TELEVISION TUBE Filed Feb. 21, 1956 2 Sheets-Sheet 2 3,038,095 CGLOR TELEVISION TUBE William J. Knochel and James A. Halt, Elmira, NY, as-

signors to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Filed Feb. 21, 1956, Ser. No. 566,921 1 Claim. (Cl. 313-35} This invention relates to color television tubes and more particularly to means for supporting and positioning large area electrodes within said tubes. One specific application of our invention is Within a color television tube such as described in Us. Patent 2,871,087, issued January 27, 1959, entitled Method of Assembling a Color Television Tube by W. l. Knochel, and assigned to the same assignee. The above patent is directed to the shadow mask type tube utilized in color reproduction.

The shadow mask tube is comprised of means for generating three separate electron beams of different trajectories on which video modulation may be impressed representative of the three primary colors. The red video information, the green video information and blue video information are impressed on separate electron beams so that video modulation of only one color is impressed on each beam, A display screen is positioned on or near the viewing face of the cathode ray tube and consists of a symmetrical arrangement of red, green and blue elemental areas of a color emitting material such as phosphor. Between the source of the electron beams and the phosphor screen and normally adjacent the phosphor screen there is placed a thin perforated sheet of material forthe purpose of partially masking'the electron beams. By proper registration of the apertures within the shadow mask electrode with the elemental areas of phosphor on the screen it is possible for the electron beams modulated with given colors to strike only the corresponding color emitting phosphor area on the screen due to the difference of the trajectory angles of the electron beams.

The description and operation of the shadow mask tube is more fully described in the following articles A Three-Gun Shadow Mask Kineoscope by H. B. Law in the October 1951 issue of the Proceedings of the I.R.E., and The CBS. Colortron, a Color Television Tube of Advance Design by N. F. Fyler, W. E. Rowe and C. W. Cain, in the January 1954 issue of the Proceedings of the I.R.E. The latter article described briefly a version of this tube having a substantially rectangular face with bowed sides and rounded corners. This version has such substantial advantages in permitting compact receiver cabinet design that only the rectangular version will be considered in this patent.

The operation of the shadow mask tube described in the above-mentioned articles has been proven satisfactory. However, the cost of manufacturing such a tube is one of the main drawbacks in the reduction of the cost of color television receiving sets. The major difficulty in reducing the cost of the color television tube is to properly position and retain the shadow mask within the tube and also to obtain and maintain correct registration of the apertures in the shadow mask with respect to the phosphor areas of the phosphor screen.

It is therefore an object of our invention to provide a novel support arrangement for the shadow mask electrode within a color television tube.

It is another object to provide an improved support arrangement for obtaining and maintaining correct registration of a shadow mask electrode within a rectangular color television tube.

It is another object to provide an improved support arrangement for a shadow mask electrode within a rec,- tangular color television tube whereby the screen and 3,38,@% Patented June 5, 1962 shadow mask electrode may be mounted and processed within one unit prior to sealing permanently within the envelope.

It is another object to provide an improved support arrangement for accurately locating and retaining a platelike electrode within the enlarged portion of a cathode ray tub It is another object to provide an improved support arrangement for a shadow mask electrode adapted for supporting and retaining the mask within a rectangular all-glass envelope.

It is another object to provide an improved support arrangement for a rectangular shadow mask electrode within a color television tube in which the support elements cooperate and are integrated to provide an improved arrangement.

These and other objects are effected by our invention as will be apparent from the following description taken in accordance with the accompanying drawings throughout which like reference characters indicate like parts and, in which:

FIG. 1 is a perspective view partly in section of a rectangular color television tube embodying our invention;

FIG. 2 is a view illustrating the interior of the face panel of the tube shown in FIG. 1;

FIG. 3 is an exploded view partly in section illustrating one embodiment of the mounting of the shadow mask electrode and beam shield within the face panel; V

FIG. 4 is a sectional view illustrating the retaining member employed in FIGS. 1, 2 and 3; and

FIGS. 5, 6, 7 and 8 illustrate possible modifications in the retaining member illustrated in FIG. 4.

Referring in detail to FIGS. 1, 2, 3 and 4, a color television tube is shown comprising an envelope 10 having a funnel section 12 and a face panel section 14. The funnel section 12 may be further broken down into a neck portion 16 and a flared portion 18. Positioned within the neck portion 16 of the envelope 10 are three

electron guns

2G, 22 and 24 of suitable design for generating and directing three different electron beams of different trajectories. Positioned on the exterior of the neck portion 16 are suitable electromagnetic deflection coils (not shown) for causing the electron beams to scan a suitable raster.

The face panel section 14 may be broken down into a faceplate portion 26 and a skirt portion 28. Deposited on the interior surface of the viewing window or faceplate portion 26 of the face panel 14 is a phosphor screen 30. The screen 30 may be comprised of a single layer of a plurality of elemental areas 32 of phosphor materials representative of the three primary colors. Each of the areas is representative of only one color and the areas are deposited in any suitable symmetrical arrangement. An organic or lacquer film is applied using the flow-filming technique described in US. Patent 2,770,557, issued November 13, 1956, entitled Cathode Ray Tube Screen Filming by a Flow Method by E. Atti and assigned to same assignee. An electron permeable conductive coating 34 such as aluminum is deposited on the interior surface of the face panel 14 including the lac quer film and exposed surface of the phosphor screen 30 to provide an electrode for the phosphor screen 30. P0- sitioned adjacent to the phosphor screen 30 is the apertured shadow mask electrode 40 of a suitable conductive matterial such as a copper nickel alloy, iron, or 1010 steel. A conductive coating 44 is also provided of a suitable material such as a graphite suspension or evaporated aluminum on the interior surface of the flared portion 18 of the envelope 10 and extending into the neck portion 16. A suitable accelerating potential is applied to these conducting coatings 34 and 44- which are in electrical contact by means of an anode button (not shown) provided on the flared portion 18 of the envelope in a manner Well known in conventional black and white television tubes. Electrical contact between conducting

coatings

34 and 44 is assured by painting two or three strips 64, approximately /2" wide on the inside of the panel skirt, on the long sides. The strips 64 start on a support land 50 and on an opposite locating projection 52 and extend continuously up the panel wall to a distance approximately 1%" from the edge for electric seal and /1" for solder glass type bulbs. The strips 64 should be of a substantially nonoxidizable material such as silver or gold.

In the drawings only one aperture 42 is illustrated in the shadow mask electrode 40 for reason of clarity but it is understood that a plurality of apertures 42 are provided therein with a similar number of phosphor dots or areas 32 provided for each of the three colors on the phosphor screen 30.

The face panel 14 of the envelope 10 is formed by pressing or molding glass in order to obtain the desired thicknesses throughout its area to provide sufiicient strength in the assembled tube. The face panel 14 consists of the faceplate or viewing portion 26 and the skirt portion 23 provided thereon. The face panel 14 is provided with support lands 50 on the interior surface of the face panel 14- which are molded integrally with the interior surface of the faceplate 26 and the skirt 28 and disposed at the angle formed between the faceplate 26 and the skirt 28. In the specific embodiment shown seven support lands 50 are provided and are spaced about the periphery of the faceplate panel 14.

In addition to the support lands 50 provided on the interior surface of the face panel 14 there are also three ball-like projections 52 provided near the angle formed by the skirt portion 28 and the face plate 26 which pro vide means for supporting and preventing lateral movement of the masking electrode 40 when mounted within the face panel 14. The masking electrode 40 has its periphery resting on the support lands 50. In addition, three positioning members 54 in the form of a W welded to the periphery of the mask engage the three ball like projections 52 to support and prevent lateral motion of the mask. This number of lands and projections has been found sufficient to support and space the masking electrode 40 with respect to the phosphor screen 30.

The above described support lands 50 and projections 52 provide the means of spacing the mask 40 with respect to the phosphor screen 30 and also preventing lateral movement of the mask 40. It is also necessary to provide means of retaining the masking electrode within the face panel and securing the masking electrode 40 therein to prevent any movement after the color television tube is sealed off. In the specific embodiment shown in FIGS. 1, 2, 3 and 4, the retaining members 60 are molded integrally with the face panel 14. A retaining member 60 is molded integral with each support land 50, and a pair of retaining members 60 may be associated with each ball-like projection. The retaining. members 6t) therefore are thirteen in number and it is found that this number is sufficient to accurately secure the mask member 40 within the face panel 14. The embodiment shown in FIGS. 1 to 4 consists of the projection or boss 60 spaced on the skirt portion 28 of the face panel 14 with a notch 62 provided therein. The notch 62 provided within the projection 60 is disposed at an angle with respect to the inner surface of the skirt 28 with the notch 62 having its opening facing the faceplate 26 of the face panel. In this manner a resilient member such as the spring 70 illustrated is seated or engaged in the notch 62 and presses against the periphery of a beam shield 80 which is in turn provided with spring members 82 pressing against the mask 40. The shadow mask 40 is thereby retained Within the face panel 14 of the tube. In the specific embodiment intermediate spring members 82 are utilized but the spring members 70 may press directly against the mask 48. The resilient spring member 70 may be designed so as to retain the masking electrode within the face panel by simply pressing on the mask 49 or beam shield 89 or it may be necessary to fasten the spring to the member by any suitable method such as welding or crimping of the spring member 70. Altcrnately, the beam shield 89 and the

springs

32 and 70 may be eliminated and the mask secured by wire springs engaging the

notches

62 and 74 in the hold down members 60 and bearing directly on the mask. The beam shield function may then be performed by a flexible light strip, for example aluminum foil which is shaped to approximate the contour of the mask rim and touches the panel wall. This shield may be held in place by the springs which secure the mask. A groove 74 is also provided in the support lands 50 adjacent the projection 69 to provide additional means of positioning the resilient member 70 or other wire or leaf springs used to retain the aperture mask.

In FIG. 5 there is shown a modified retaining member 99 which is also molded integrally with the face panel 14 but separate from the support lands 5t} and positioned on the skirt portion 28 of the face panel 14 and provided with a notch 92 to retain the resilient spring member 70.

In FIG. 6 there is shown another embodiment in which again a projection 94 molded integral on the inner surface of the skirt 28 with a notch or slit 96 provided thereon is utilized for retaining the mask member within the face panel 14.

In FIG. 7 the retaining means is in the form of a recessed portion 98 within the wall of the skirt portion 28 and may be formed in the molding operation or removed in a cutting or grinding operation after the face panel 14 has been molded.

In FIG. 8 there is shown another possible method of mounting the mask electrode 40 Within the face panel 14 and the retaining member is in the form of a metallic projection 100 provided with recessed portion 102. The metallic member 100 may be placed in the glass while molten or immediately after casting or alternatively by local heating. The metallic members 100 are positioned on the skirt 28 and the recessed portion 102 provides a seat for the resilient wire or leaf spring member used to retain the mask.

By supporting the masking electrode 40 within the 'allglass face panel 14 it is therefore possible to form and process a unitary structure consisting of aface panel 14, phosphor screen 30 and masking electrode 40 and retaining members and then assembling the completed unitary structure to the funnel section 12 of the envelope and sealing the two glass members by suitable methods such as electrical sealing techniques described in the US. Patent 2,871,087 or by the utilization of solder glass techniques. The assembly permits sealing Without damage to mask or retaining members. The resulting tube provides an all-glass envelope thereby substantially reducing the envelope costs and also reducing the amount of shrinkage due to unsatisfactory metal-to-glass seals. The molded integral glass supporting means within the face panel substantially reduces the cost of manufacture of the shadow mask tube.

While we have shown our invention in several forms, it Will be obvious to those skilled in the art that it is not so limited but is susceptible to various other changes and modifications without departing from the spirit and scope thereof.

We claim as our invention:

A color television tube comprising an envelope, said envelope comprised of a glass funnel section and a glass face panel, said funnel section being comprised of a neck portion and a flared portion, said funnel section having a conductive coating on the inner surface thereof, said face panel being comprised of a faceplate viewing portion and a skirt portion, a phosphor coating deposited on the inner surface of said viewing portion, the adjoining glass edges of said flared portion and said skirt portion sealed together, a shadow mask electrode positioned within said face panel and substantially parallel to said faceplate portion, said faceplate portion having a conductive coating on the inner surface thereof and extending along said skirt portion beyond said mask electrode, lateral positioning means located on the inner surface of said face panel for preventing lateral movement of said shadow mask, non-flexible spacing means located on the inner surface of said face panel and integral therewith to provide bearing surfaces about the periphery of said masking electrode for spacing said shadow mask with respect to said faceplate, glass retaining means integral with the inner surface of said skirt portion for retaining said shadow mask within said face panel, said retaining means comprising a plurality of integral recessed portions spaced about the periphery of said skirt portion, removable holding means engaging said shadow mask and said recessed portions for holding said shadow mask against said non-flexible spacing means, and conductive strips deposited on the inner surface of said skirt portion to assure electrical connection between said conductive coatings.

References Cited in the file of this patent UNITED STATES PATENTS 2,690,518 Fyler Sept. 28, 1954 2,727,172 Mark Dec. 13, 1955 2,733,366 Grimm Jan. 31, 1956 2,755,405 Wilhelm July 17, 1956 2,942,129 May June 21, 1960