US2107784A - Envelope shield and method of depositing metal areas - Google Patents

Description

w R 1933; 7 B. c. GARDNER 3 2,107,734

ENVELOPE SHIELD AND-METHODOF,DEPOSITINGMETAL AREAS F iled May 21, 1957 INVENTOR. Baa/ 2120 C GARDNER A TTORNEYS.

Patented Feb. 8, 1938 PATENT OFFICE ENVELOPE SHIELD AND METHOD OF DE- POSITING METAL AREAS Bernard 0. Gardner, Philadelphia, Pa., assignor to Farnsworth Television Incorporated, San Francisco, Calif., a corporation-of California Application May 21, 1937, Serial No. 143,942

2 Claims. My in'vention relates to. a means and method of forming metal areas in an envelope, and more particularly to a means and method of confining these metal areas to specific locations.

This application is a continuation-in-part of my priorapplication, Serial No. 82,915, filed June 1, 1936, entitled "Means for-forming metal areas".

Among the objects of my invention are: To provide a means and method of confining metal areas formed by evaporation of metal within a container to predetermined areas of the container; to provide an expandible shield for an envelope which may be inverted through a narrow opening in the envelope and expanded to cover the walls thereof in specific locations; to provide a meansand method of forming metallic mirrors and the like on specific interior areas of an envelope" wall; and to provide a simple removable shield'gfor an envelope wherein metal areas a'a'e to be deposited.

my t inventionpossessesgnumerous otherv objects and featuresoi'" advantage, somatic! which, together with the'foregoinfif wi {be set forth in the gfollowing description or -specific apparatus embodying and utilizing my It is therefore to be understood that my method is applicable to otherapparatus, and that I do not limit myself, in any way, to the apparatus of the present application, as I may adopt various other apparatus embodiments, utilizing the method,

within the scope of the appended claims.

In my prior application, referred to above, I

. have described and claimed an expandible cupshaped shield that may be inserted in an envelope to cover certain definite portions of the wall thereof while metal is being evaporated therein,

to the end that the evaporated metal may be con- 1 fined to those areas of the tube not covered by the shield.

The present invention deals with a similar problem, but in this case the shield is simpler in construction and is prepared for placing within the envelope by being rolled upon itself. The shield is made of a resilient material so that it may be rolled into a small volume, inserted through anarrow opening, andthen expanded to cover the walls of the envelope in predetermined locations.

My. present invention isadaptedfor use on both cylindrical walls and conical walls.

My invention may be more fully understood by direct reference to the drawing, wherein- Figure 1 is a perspective view of a cylindrical walled envelope showing two shields; one inserted ing sizes of envelopes.

and expanded, and the other rolled preparatory to insertion.

Figure 2 is a perspective view of 'a conical walled envelope showing an inserted shield and one prepared for' insertion. v 5

Figure 3 is a sectional view and diagram showing a metallic filament in position to evaporate metal onto the inner walls of the container shown in Figure 2, with shield in place.

Referring directly to Figure i; an envelope I 10 of glass, quartz. or similar non-conducting material, preferably vitreous, has a narrow neck portion 2. As it may be desirable to evaporate metal in the form of a thin layer on the interior of the envelope, particularly 'on the closed end 3, 15 I prefer to insert a metallic shield within the envelope. In this case the metallic shield comprises a split band I of resilient material, such as thin phosphor bronze, for example, which will expand to the form of a cylinder when uncon- 20 fined.

In order to insert the shield within the envelope I the split band 4 is wound into a tight roll 5 so that the diameter of the roll is less than the size of the opening of the narrow portion 2. The 25 roll I is then pushed into the container, and the natural resiliency of the material will expand it to contact the walls of the container. It is obvious that containers having different size openings and different diameters of the expanded 30 portions may be accommodated by the use of the same split band 4, inasmuch as the overlap 0 will be greater or less in accordance with the diameter of the expanded portion. It is clear that the shield may be adjusted up and down in the 5 container to cover specific areas of the walls, and also, that the split band may be of different lengths to accommodate long or short shielded areas.

In Figure 2, I have shown a modification of 40 my invention adapted for use within envelopes vhaving conical walls, and here the envelope i is provided with an expanded portion having conical walls 1 The split band in thiscase is preferably not a rectangle, but is so shaped that when 45 it is expanded to the conical shape desired, in contact with the walls of the envelope, the upper edge will describe a circle in the envelope. Such shapes may be readily cut from metal for very- In this case, a conical 50 split band 8 is wound into a conical roll 9, having its greatest diameter less than the diameter of the narrow portion 2, and is inserted in the same manner as split band I, whereupon it will expand to fit the container. 55

proper location within the envelope metal may then be evaporated therein, as shown in Figure 3. Here, the envelope I, havng conical walls 1 and conical split band 8,. is mounted on a base plate 9 and sealed thereto by a vacuum tight cement I0, such as sealing wax, for example. Extending upwardly from base plate 9' are two filament leads H passing through insulators 12 into the base plate, and carrying at their upper end a metallic filament M, such as'nickelor silver. The interior of the envelope l is in contactwith a vacuum pump l5'through a vacuum'li-ne l5 extending through base 9. Filament is energized by filament source l1. under the control of filae ment resistor l8;

In operation, the shield- 8,'isadjusted in the proper location within the tube. The narrow end 2 is sealed to the base 9 and the pump 15 is started to partially exhaust the air in the container to the point where oxidation of the filament will not take place to any great extent. After this amount of vacuum has been. reached .the filament H is gradually heated by, passing" current from source I! therethroughmp'to the vaporization pointiof'r the filamentmateri'aL Atthispoint metallic vapor. is emitted and'will.de posit onthe walls of the envelope above the shield 8, the upper edge of the shielddrawing a sharp line of demarcation between the depositedv metal layer and the clearremainde'r of. the: envelope covered. by theshield." 'After a deposit of surficient thicknesshas beerrobtained on the exposed wall the envelope is let down to atmospheric pressure, removed from the base plate, and the shield removed by re-rolling and withdrawing through the opening. The envelope may then be utilized as desired, as a lamp, for example, or as a cathode ray tube.

It is obvious that my invention is adapted to containers having various types of walls,.and the embodiments shown herein areto be considered, therefore, asexamples only, of my method as practiced.

I claim:

1. In combination with an envelope having a narrow neck, means ithin said envelope for evaporating a'wall coating on the inner surface thereof, and means for limiting the area covered by said wall coating comprising a rolled metal sheet of sufiicient sizeto enter saidjaarrow neck and of sufiicient resiliency to expand after insertion to coverthe areas to be protected from evaporation.

- 2. The method of temporarily covering the inner wall of anenvelope having a narrow openingwith aresilient sheet during the evaporation of metalv therein which comprises rolling said sheet upon itself until the roll is of small enough diameter to enter the opening, releasing the roll toexpandsaid sheet to form a band covering an area of said wall, evaporating metal within said envelope, re-rolling said'sheet andv removing it while rolled through said opening.

. BERNARD c. GARDNER.

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