US3420593A - Getter assembly - Google Patents

Description

Jan. 7,1969 A, J; IN 3,420,593

9 GET'IER ASSEMBLY Filed Feb. 23, 1957 INVENTOR.

' ADEN J. KING.

ATTORNQEY.

United States Patent 3,420,593 GETTER ASSEMBLY Aden J. King, Syracuse, N.Y., assignor to King Laboratories, Inc., Syracuse, N.Y., a corporation of New York Filed Feb. 23, 1967, Ser. No. 618,096 US. Cl. 316-30 Int. Cl. H01j 7/20 6 Claims ABSTRACT OF THE DISCLOSURE In gettering cathode ray tubes, the getter is positioned in the neck of the tube, or in the rear portion of the conical section of the tube. In either event, the getter is positioned in close proximity to the glass envelope of the tube. This is so because of the limited available space in the neck portion, and when positioned in the conical section, which is more often the case, the getter must be positioned near the glass envelopeotherwise, the getter will interfere with the electron beam and produce a shadow at the edge of the picture.

Upon the flashing of the getter, the temperature of the getter increases from room temperature toas high as 1200 C., within a period of five to ten seconds. This rapid rise in temperature creates a strong thermal stress in the glass envelope in the area adjacent to the getter. This results, on occasion, in the envelope cracking whereupon the tube, which at that time has been completed, is lost.

This invention has as an object a getter assembly including a thermal barrier, or insulating shield, which is effective to greatly reduce the amount of heat from the flashing getter reaching the inner surface of the tube envelope and thereby to prevent or reduce the possibility of the cracking of the envelope as a result of thermal shock.

In the drawings- FIGURE 1 is a view diagrammatically illustrating the getter assembly mounted in a cathode ray tube.

FIGURE 2 is a view taken on line 2-2, FIGURE 1.

FIGURE 3 is a view taken on line 33, FIGURE 2.

FIGURE 4 is a view taken on line 4--4, FIGURE 3.

FIGURE 5 is a plan view of the supporting strip employed in the assembly shown in the previous figures.

FIGURE 6 is a view, similar to FIGURE 3, of a modified form of attachment of the assembly to the supporting strip.

FIGURE 7 is a view taken on line 7-7, FIGURE 6.

FIGURE 8 is a bottom plan view of the getter assembly showing a further modified arrangement for attaching the thermal barrier to the getter body.

FIGURE 9 is a view on line 99, FIGURE 8.

FIGURES l0 and 11 are cross sectional views of the barrier of the type shown in FIGURES 8 and 9, illustrating different configurations thereof.

In FIGURE 1, the neck portion of a cathode ray tube is indicated at 10, and the conical section at 11. The greater assembly 12 is shown positioned in the conical section 11, the getter being carried by a support 13 fixed to the gun 14. The getter comprises an annular metallic body member 15, U-shaped in cross section, the annular trough member containing the gettering alloy 16. The body 15 is fixed to the supporting strip 13, as by spot welding, or the like. A circular thermal barrier 17 having a diameter comparable to the diameter of the getter body 15, is fixedly secured to the body 15 at the under side thereof.

In FIGURES 2 to 5, the barrier 17 is formed with a Patented Jan. 7, 1969 diametrically extending rib 20, formed at each end with an inwardly extending slot 21. The support strip 13 is formed at its end with a tab 22, which is bent downwardly and inwardly into one of the slots formed in the rib 20. The supporting strip 13 is also formed with a tab 23 located in spaced relation to the end tab 22. The tab 23 is bent downwardly from the plane of the strip and inwardly into the slot or recess formed at the opposite end of the rib 20, see FIGURE 4.

By this arrangement, the barrier 17 is fixedly secured to the getter by simple tooling in the mass production of the getter assembly. The rib 20 serves as a means for orienting the barrier for correctly positioning the slots in the rib 20 to receive the tabs 22, 23, as the body and supporting strip are moved in juxtaposition to the barrier, with the support strip extending in a direction parallel to the rib 20. The tabs are then bent into the slots in the rib by reciprocating punches mounted in the assembly jig.

-In 'FIG'UR'ES 6 and 7, the barrier 17 is formed with a circular projection 27 located centrally of the barrier. The projection has a through aperture, the outer portion of which is counterbored. A metal disk 30 is positioned in the counter-bore and is formed with a central projection 33 extending through the aperture in the barrier into engagement with the support strip 13. The projection 33 is spot welded to the supporting strip 13, this operation being readily performed as one electrode of the welder can be passed through the central aperture of the getter body into engagement with the strip 13, and the other electrode can be applied to the member 30.

It will be apparent other constructions may be employed to attach the barrier to the getter. For example, the supporting strip 13 may be formed with a downwardly extending dimple for engagement with the member 30 in fiat disk form. Also, the getter body 15 may be provided at its periphery with downwardly extending tabs 31 which may be bent about the periphery of the barrier, see FIGURES 8 and 9 in which the under side of the barrier is formed with notches 33 to receive the inwardly bent ends of the diametrically opposed tabs 31. The barrier, in the arrangement shown in FIGURES 8 and 9, may be formed with a peripheral flange 35, as shown in FIGURES 10 and 11, and may be formed with a central recess 38, as in FIGURE 10.

The barrier 17 may be formed of material such as mica, or glass. It formed of glass, it is necessary that the glass be opaque to radiant heat. Preferably, the barrier is formed of ceramic material which should be vitrified and have high density so as not to contain any gases, or moisture, which could be released to the tube during the high temperature rise incident to the flashing of the getter. The material from which the barrier is formed should also have a low coefiicient of heat conductivity and a low thermal expansion coelficient. The former is particularly important if the getter is positioned in direct contact with the barrier, as in FIGURES 8-11, and the latter is required for resistance to breaking under the severe thermal shock occuring during flashing of the getter.

In the two forms disclosed in FIGURES 2 to 7, the barrier is spaced a slight distance from the getter body as determined by the thickness of the support strip 13. It is also positioned a distance from the glass envelope 11 by the rib 20, or the circular projection 27. Since the intensity of thermal radiation decreases with the square of the distance, these spacings are particularly helpful in effectively reducing heat transfer from the getter to the envelope of the tube. The projections either in the form of the rib 20, or the projection 27, are rounded and smooth. This is of importance when the getter assembly is mounted in the conical section of the tube, as the supporting strip 13 is in the form of a curved spring. When the electron gun 14 is inserted into the neck portion of 3 the tube, the getter assembly slides along the Dag covering the inner wall of the tube. With the barrier formation on the getter being rounded and smooth, the Dag is not scraped, or abraded, from the inner surface of the tube.

What I claim is:

1. A getter assembly comprising a body containing getter material, a support fixedly secured to said body for supporting the same in the tube in proximity to the inner surface of the tube envelope, a thermal barrier fixed relative to said body and positioned intermediate said body and said envelope.

2. A getter assembly as defined in claim 1, wherein said barrier is formed of ceramic material.

3. A getter assembly as defined in claim 1, wherein said barrier is formed of dense vitrified ceramic material.

4. A getter assembly as defined in claim 1, wherein said barrier is of discoidal form and provided with a projection extending toward the tube envelope.

5. A getter assembly as defined in claim 1, including means located at the center of said barrier for fixedly securing the same to said body.

6. A getter assembly as set forth in claim 1, wherein said support is provided with tabs interlocking with said barrier.

References Cited UNITED STATES PATENTS 3/1959 Gray 316-25 7/1958 Coltrin 31630

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