US2755405A

US2755405A - Color television tube

Info

Publication number: US2755405A
Application number: US386167A
Authority: US
Inventors: John F Wilhelm
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1953-10-15
Filing date: 1953-10-15
Publication date: 1956-07-17
Anticipated expiration: 1973-07-17

Description

y 17, 1956 I J. F. WILHELM 2,755,405

COLOR TELEVISION TUBE Filed Oct. 15, 1953 INVENTOR.

United States Patent CQLOR TELEVISION TUBE John F. Wilhelm, Lancaster, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application October 15, 1953, Serial No. 386,167

Claims. (Cl. 3'1392) This invention relates to improvements in cathode-ray tubes and to improvements in the art of manufacturing the same.

In the art of manufacturing glass cathode ray tubes of the color kinescope type certain difliculties are encountered. One of the principal difficulties arises due to the fact that optimum performance can be achieved only when the gun elements and the target, or screen elements, are mounted in substantially perfect alignment. In order for tubes of this type to be manufactured in large numbers and utilizing mass production techniques, this alignment must be accomplished in a very simple manner.

There are presently available several known methods of supporting the gun, or battery of guns, in glass envelopes that satisfy the requirements of mass production. However, when using glass envelopes many problems remain in the presently available means of support for the target assembly. Some of these latter problems are: simplicity of the support members, to permit manufacturing in large quantities without the cost thereof being a prohibitive factor; strength of the support members, to insure rigidity of the target when the tube is moved; ease of assembly, to permit the use of non-skilled labor when assembling the tubes; expansion characteristics of the target support means must substantially match the expansion characteristics of the glass envelope and the target or, in the alternative, the support means must be constructed to permit differences in the expansion characteristics, to avoid undue stresses and strains in the various elements; and, the target support means should be of a type that would not require extra steps in the assembly of the tube such as orientation of the target.

It is therefore an object of this invention to provide a new and novel means to support a target in a glass envelope of a tri-color cathode ray tube.

It is another object of this invention to provide a tube structure which shall lend itself readily for use in mass production of color kinescopes of the glass envelope type.

It is a further object of this invention to provide a method of and means for aligning a screen assembly of the masked target variety with respect to an electron gun, or a battery of guns, in a glass envelope for a color television cathode ray tube.

The foregoing and other objects are accomplished in accordance with this invention by providing a mount for a tri-color screen assembly in a glass bulb which includes a plurality of glass registry-support means in the funnel portion of the glass envelope, and matching support means in the glass face panel portion of the envelope. Placed between the support assemblies is a spring mount for the tri-color target, or screen, assembly which supports the screen assembly in rigid suspension within the envelope. In the alternative the glass face panel may be so shaped as to engage a spring mount whereby a restraining influence is exerted, and the tri-color screen assembly is held in suspension within the envelope.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof will best be understood by reference to the following description when read in connection with the single sheet of accompanying drawings in which:

Figure 1 is a diagrammatic view of a cathode ray tube utilizing a glass envelope;

Figures 2 through 4 are enlarged fragmentary sectional views of a cathode ray tube each utilizing an embodiment of this invention;

Figures 5 and 6 are enlarged fragmentary sectional views of embodiments of the target support means in accordance with this invention; and

Figure 7 is a diagrammatic view of an end of a cathode ray tube showing possible orientation of the support means in accordance with this invention.

Referring in detail to Figure 1, there is shown a diagrammatic View of a cathode ray tube 10 of the tri-color kinescope variety. The glass envelope of tube 10 comprises a hollow glass frustrum portion 12 having a glass face panel 14 sealed across the larger of the two apertures,

and a glass neck 16 sealed across the smaller aperture.

Enclosed within the neck portion 16 is an electron gun, or battery of guns, 18 which may be any of the conventional types of electron guns. Arranged closely adjacent the glass face panel 14 is a target assembly 20. The target assembly 20 may be of the masked target variety wherein the correct spacing between the thin metal mask, and the alignment of its apertures with respect to the color emitting phosphor elements may be fixed by a suitable frame or other spacing elements during the manufacture of this sub-assembly in the manner taught in U. S. Patent 2,625,734 granted to H. B. Law on January 20, 1953. In the alternative the target assembly 20 may include only the shadow mask while the color emitting phosphors are supported on the face panel 14. When the latter arrangement is utilized the shadow mask is curved to equal the radius of curvature of the glass face panel 14. The alignment of the shadow mask and the phosphors in the latter arrangement are described hereinafter. For purposes of this invention it is assumed that the battery of guns 18 has previously been aligned with respect to each other as a separate sub-assembly.

Even though the battery of guns 18, have been previously aligned one with the other there remains the problem of alignment, or registration, of the target assembly 20 with the electron guns 18. In other words the entire target assembly 20 must be located within the envelope in such a manner as to have the electron beams from guns 18 bombard the target 20 in the proper location. The solution of this alignment problem is complicated by the fact that certain types of elements are excellent support members but they are subject to movement when heated due to expansion and contraction as a result of variations in temperature. Any movement of the target assembly 20 is undesirable in that the electron beams will no longer land on the correct areas of the target. Furthermore, if metal elements of conventional design are used to support the target assembly 20, differences in the coefiicient of expansions of the metal support members and the glass portions of the envelope are likely to produce strains and cracks in the glass at points where the metal touches glass.

Referring now to Figure 2 there is shown an enlarged fragmentary view of a support structure for the target assembly 20 in accordance with this invention. In this embodiment of the invention the target assembly 2% is supported by a plurality of circumferentially spaced spring elements 22 which are supported between a plurality of circumferentially spaced glass protuberances, or posts 24 on the glass frustrum 12 and a plurality of circumferentially spaced protuberances, or posts 26 on the glass face panel 14. For simplicity in the drawings only one support means is shown in Figures 2 through 6. The spring elements 22 may be of a material such as tungsten or high grade steel, or the like and are connected to the frame 30 of target assembly 20 by a weld 28 or other similar bonding operation. The

glass support posts

24 and 26 on the frustrum 12 and face panel 14 respectively may be formed as the glass is molded, or as an alternative, the glass posts or

protuberances

24 and 26 may be added after the frustrum 12 and face panel 14 have been formed by being fused or by other conventional means of bonding glass-to-glass.

Each of the

glass posts

24 and 26 preferably includes a

grooved portion

24 and 26 respectively into which the springs 22 snap fit and thus prevent movement of the springs 22 whereby any rotation of the target assembly 20 is eliminated. The springs 22 may extend into the target assembly 20 as shown adjacent post 24 as long as the springs 22 do not interfere with the elements included within the target assembly 20 and do not interfere with the elements included within the target assembly 20 and do not extend out to a point where they will be seen when the cathode ray tube is in operation. The number and location of the springs 22 and

posts

24 and 26 will be discussed hereinafter.

When practicing this invention the assembly of the cathode ray tube 10 may be as follows: When the glass frustrum 12 is molded a plurality of posts 24 are also molded at various circumferentially spaced locations around the axis of the envelope. During the process of molding the glass face panel 14 the glass posts 26 may also be molded at spacings to match the locations of posts 24. When the neck portion 16 is sealed to the smaller aperture of the glass frustrum 12 the battery of electron guns are aligned with respect to a particular spot on the frustrum 12. One such spot could be one of the glass posts 24. When these steps have been com pleted and the plurality of springs 22 bonded to the frame 30 for the target assembly 20 by a weld 28, the springs are snapped in the grooves 24 of posts 24 on the glass frustrum 12. At this time the glass face panel 14 is placed on top of the springs 22 and pressed until the frustrum 12 and face panel 14 are in contact. The elements are held in this relation until a suitable vacuum tight seal is made between the various glass portions. By pressing on the frustrums 12 the target assembly is actually held in suspension by means of the springs 22.

The seal between the frustrum 12 and face panel 14 is preferably a low temperature seal to avoid damaging, by heat, the various phosphor particles in the target assembly 20. One such low temperature seal is the type of seal obtained when a low melting point glass is used as a frit. In the alternative a thin metallic coating may be applied to the glass and a radio frequency current seal utilized. When these seals are utilized a vacuum seal may be made at temperatures in the order of 400 C.

Due to the fact that no portion of the target assembly 20 is in direct contact with any portion of the glass supporting means, and due to the resilient action of the springs 22, expansion and contraction of the various elements is immaterial in that any expansion or con traction of the elements is absorbed by the resilient properties of the springs 22. Thus, even though the target assembly 20 expands, no movement of the target assembly as a whole occurs but merely greater compression of springs 22. When the target assembly contracts the springs 22 are less compressed and the target assembly as a whole remains in the same position.

When the phosphor particles are placed directly on the face panel 14 the alignment between the phosphor particles and the shadow mask is obtained by selecting a predetermined spacing between these elements. After the spacing has been determined the size of springs 22 is selected so that when the springs 22 are under compression within the envelope, i. e. the snap fit is obtained, the correct spacing is automatically obtained.

Referring now to Figure 3 there is shown an enlarged fragmentary view of an embodiment of this invention. In this embodiment the frame 30 which supports the apertured shadow mask 31 of the tri-color screen assembly are supported by being placed between springs 32 and springs 34. The springs 32 are arranged to snap fit into grooves or apertures in the posts 26 on the face panel 14 as was described above. The springs 34 are of the type shown and are locked into position by having one end snapped into grooves 25 in posts 24 on the glass frustrum 12. Due to the fact that springs 34 are locked to the posts 24 rotary movement of the target assembly about the axis of the tube is eliminated. Due to the tensile properties of springs 32 and 34 movement of the target assembly along the axis of the envelope is also eliminated.

The assembly of this embodiment is substantially the same as that described in connection with Figure 2 except for the presence of the locking grooves 25 in the support posts 24. The locking grooves 25 may be formed in the glass posts 24 when the frustrum 12 is molded, or at a later time. The springs 34 are preferably attached to the posts 24 before the tri-color screen frames 30 are inserted to avoid as much stress on the frames 30 as is possible whereby damage to the phosphors is prevented. The phosphor particles (not shown) may be supported by the frame 30 or may be supported by face panel 14 as desired.

Expansion and contraction of the various elements shown in Figure 3 is absorbed by springs 32 and 34 substantially the same as was described in connection with springs 22 of Figure 1. Therefore, further description thereof is not deemed necessary at this time.

Referring now to Figure 4 there is shown a fragmentary sectional view of an embodiment of this invention wherein the target assembly 20 is supported entirely within the front face panel 14. In this embodiment the face panel 14 includes a plurality of locking slots, or gutters, 40 and 41. The locking

slots

40 and 41 may be formed when the face panel 14 is molded or may be cut thereafter and are preferably just large enough to receive the curved ends of spring 44 so that rotary movement of the target assembly 20 around the axis of the tube is eliminated. The springs 44 may be attached to the target assembly by a weld 43, or by being bolted or fitted.

In the embodiment of Figure 4 the battery of electron guns 18 are aligned in the neck 16 with respect to a particular spot on the glass frustrum 16. When the springs 44 have been locked into position in the face panel 14 the target assembly is locked into position. If the seal between glass frustrum 12 and glass face panel 14 is now made the guns 18 are automatically aligned with the elements of the target assembly 20.

In any of the embodiments of the invention shown in Figures 2 through 4 it should be understood that the target assembly 20 may comprise the three color emitting phosphor particles, the shadow mask 31 and the target frame 30. Or, in the alternative, the phosphors may be placed on the inner surface of the face panel 14 and the target assembly includes only the shadow mask 31 and the mask frame 30. When the latter arrangement is utilized the shadow mask is preferably curved (not shown) to match the radius of curvature of the face panel 14.

Referring now to Figure 5 there is shown a modification of the invention wherein a spring 50 is joined to the extended surface of the target assembly 20 by

welds

51 and 52. In this modification the spring 50 may be connected to frame 30 of the target assembly by means of bolting or fitting as an alternative to

welds

51 and 52. When the target assembly is fitted into an envelope similar to that shown in Figure 1 the target assembly 20 will be in suspension as was explained previously.

Referring now to Figure 6 there is shown a modification of this invention wherein the springs 6-9 are bolted to the internal surface of the frame 3% for the tri-color screen assembly by bolts 61 and 62. As is understood by those skilled in the art the spring 69 could also be attached to the frame 30 by means of a weld or by being fitted.

Referring now to Figure 7 there is shown a possible orientation for the target support means described in connection with Figures 2 through 6. In this orientation the support means are arranged at

positions

70, 71 and 72 which are arranged 120 from each other within the cathode ray tube 10. Other orientations may also be used as well as a larger or smaller numbers of support means. However, for the sake of economy the smallest number that results in rigid support of the screen assembly 20 is desirable. Therefore, three supporting positions as shown in Figure 7 are preferable. As can be seen when support positions 79, 71, and 72 are utilized movement of the target assembly is eliminated. Due to the grooves in the support posts no rotational movement is possible, i. e. the target is oriented or indexed within the tube 10. Furthermore movement of the target assembly transverse the axis of the tube is also eliminated by the tensile properties of the springs and the fact that in order for the target to move two of the springs must move out of their respective grooves.

What is claimed is:

1. A cathode-ray tube comprising, an envelope, said envelope having supporting means within said envelope, an apertured member, spring means secured to said apertured member, said spring means being in contact with and supported by said supporting means said supporting means and said spring means having interengaging index means for determining the angular orientation of said apertured member with respect to said envelope.

2. A cathode-ray tube comprising, a glass envelope having supporting means comprising recesses spaced around the axis of said envelope, an apertured member within said envelope, resilient springs secured to said apertured member, each of said resilient springs being under compression and engaging one of said recesses.

3. A cathode-ray tube comprising, a glass envelope including a target assembly having outwardly extending resilient support members thereon, mounting lugs integral with the inner surface of said envelope and positioned around the axis of said envelope and each of said support members engaging a pair of said lugs.

4. A cathode-ray tube comprising, a glass envelope having a neck portion containing an electron gun, and a main chamber containing a target assembly, said target assembly having a plurality of circumferentially spaced outwardly extending resilient support members thereon, a plurality of circumferentially spaced inwardly extending glass support means integral with the inner surface of said envelope and receiving said resilient support members whereby said target assembly is resiliently supported in a predetermined radially oriented spaced relationship with respect to said envelope.

5. A cathode-day tube assembly comprising an envelope, said envelope including a frustrum portion having a glass face panel closing the larger opening thereof and a neck portion including at least one electron gun closing the smaller opening thereof, a target assembly within said envelope and arranged adjacent said face panel, resilient support means connected to said target assembly, and indexing means within said envelope receiving a portion of said resilient support means to resiliently support and index said target assembly within said envelope.

6. In a cathode-ray tube assembly, a hollow frustrum forming a portion of the envelope for said cathode-ray tube, a glass neck portion closing the smaller opening of said frustrum and forming a portion of said envelope, a glass face panel closing the larger opening of said frustrum and forming a portion of said envelope, a plurality of indexing means mounted in circumferentially spaced array on the inner surface of said envelope and adjacent said larger opening of said frustrum, a target assembly, resilient members arranged in substantially the same circumferentially spaced array as said indexing means and connected to said target assembly, and said resilient members being supported by said indexing means, whereby said target assembly is resiliently supported within said envelope.

7. A cathode-ray tube assembly comprising, a glass envelope, a plurality of pairs of grooved glass support posts mounted in circumferentially spaced array on the inner surface of said envelope and adjacent the larger end thereof, a target assembly, resilient springs mounted in circumferentially spaced array on said target assembly, the spacing of said support posts and the spacing of said springs being substantially the same, each of said springs being in contact with and supported between a pair of said support posts while under compression, whereby said target is resiliently suspended Within said envelope and radially oriented with respect to said envelope.

8. A cathode-ray tube assembly as in claim 7 wherein each of said springs are connected to said target assembly by a single connection, and said single connection is substantially in the center of said target assembly with each of said springs extending outwardly therefrom and curving back toward said target assembly.

9. A cathode-ray tube assembly as in claim 7 wherein the ends of each of said springs are connected to the external surface of said target assembly with the balance of each of said springs extending outwardly therefrom.

10. A cathode-ray tube assembly as in claim 7 wherein the ends of each of said springs are connected to the internal surface of said target assembly, each of said springs extending from one of said connections around the external surface of said target assembly and back to the other of said connections.

References Cited in the file of this patent UNITED STATES PATENTS 2,123,957 Orth s- July 19, 1938 2,195,444 Brett Apr. 2, 1940 2,425,980 Baird Aug. 19, 1947 2,546,828 Levy Mar. 27, 1951 2,661,437 Beckers Dec. 1, 1953