US2333725A

US2333725A - Photoflash casing

Info

Publication number: US2333725A
Application number: US393320A
Authority: US
Inventors: Kreidler Raymond Le Roy
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-05-14
Filing date: 1941-05-14
Publication date: 1943-11-09
Anticipated expiration: 1960-11-09

Description

Nov. 9, 1943. R. LE R. KREIDLER 2,333,725

PHOTOFLASH CASING Filed ga 14, 1941 INVENTOR 1?. A 5/0; 5?. BY

ATTORNEY Patented Nov. 9, 1943.

' 2,333,725 ICE PHOTOFLASH CASING Raymond Le Roy Kreidler, Bloomfield, N. J., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 14, 1941, Serial No. 393,320

Claims.

M invention relates to photoflash lamps, and particularly to photoflash lamps having a casing of a plastic material.

An object of my invention is to provide a flash lamp of an organic plastic having efficient light output.

Another object of my invention is to provide a casing of an organic plastic capable of containing an active gas at more than atmospheric pressure. Another object of my invent-ionic to provide an easily assembled photoflash lamp of an organic plastic casing not requiring theapplication of high temperature.

Other objects and advantagesof the invention will become apparent from the following description and drawing in which:

Figure 1 is a front elevation of a preferred embodiment of my invention substantially to its preferred actual scale.

Figure 2 is a cross sectional view on a much larger scale. I I

Figure 3 is a cross sectional view on lines III- III of Figure 2.

Figure 4 is an enlarged detail view of the interlocking joint between the bulb and base in Figure 2.

Figure 5 is a cross sectional view illustrating the sealing of one of the conductors in Figure 2. Figure 6 is a view on lines VI-VI of Figure 2 prior to the cutting off of the exhaust tube.

Figure 7 is a cross sectional view tion of the base of Figure 2.

My invention constitutes an improvement over the invention of a photofiash lamp which is disclosed in the copending application of Michael D. Margitta, filed January 26, 1940, Serial No.

My invention eliminatescompletely the problem of broken glass in connection with the transportation, utilization and disposal of photoflash lamps by my choiceoi a plastic material. The preferred construction of my photoflash lamp proximately 40 mil material as this is thin enough to be self-supporting and yet thick enough to mold properly.

The preferred material is that of cellulose acetate although vinyl compounds, butyrates, methacrylates and similar materials may be used. This cylindrical portion preferably has a curved closed end H. The base portion I? of the lamp is preferably of the same material and is dishshaped having an upper edge 13 with a recessed portion M to receive the edge iii of the bulb portion I 0. The bulb portion lll preferably has a slight rounded rim 16 on its periphery near the edge l5 and this projecting rim i6 is adapted to be forced-into locking engagement with a corres ponding groove IT on the inner face of the recess M by the slight resiliency of the cellulose acetate wall l0. Theinterlocking joint between the bulb of a modificaedge l5 and the base rim l4 under the compressed bulb edge l5 has a mechanical strength to prevent separation of the two portions under any increased pressure during flashing operations.

The base has preferably a central depressed portion 20, from which extends a central tubulation 2| for the purpose of exhausting and filling the tube with an active gas such as oxygen. The lamp has two connections or

standards

22 and 23, preferably of copper and bound in spaced relationship with each other by ahead of insulation 24 which maybe of glass or ceramic material, a tungsten filament 25,- and, preferably attached :theretafigniting means 26 and 21 formed by dipping the conductors and filament into a nitro- -=cellulose binder containing powdered zirconium,

.magnesium and potassium perchlorate.

The conductors 22" and 23 where they pass through the base are preferably flattened as indicated at 28 in Figuresz and .5. Thebase has two integral tubular projections 29 surrounding this flattened portion of .the conductors. The conductorsare sealed to the projecting portions 29 by having two preferably slightly heated flat also eliminates the necessity of high temperatures during assemblage of the device. My invention also has the advantage that it permits the utilization of oxygen inside of a photoflash lamp at greater than atmospheric pressure. With glass casing lamps at the prior art, there would be danger of flying particles of glass from the posslbility of explosion as the result of the greater pressure of gas therein.

In Figure 1 I have disclosed an eievational view of my'photoflash lamp in its preferred actual size. The structure ofthis .photofiash lamp'is more clearly disclosed in Figure 2. The bulb portion H! is preferably a closed end cylinder of an I organic plastic translucent to light and prefermetal surfaces 30 and3l, pinch the cellulose acetate projection 29 about the flattened surface 28 of the conclucto'rs, as illustrated in Figures 5 and 6. The inner surface of the bulb and preferably also the base. is sprayed with a .coating. 32 of a transparent inorganic material ."that will not readily combine with oxygen zit-instantaneous h temperatures.

The material which we have found most suitable is that of sodium silicate. Other-"transparent inorganics that might be used are those sold under the trade names of "Abapon and Stacol." The interior of the'bulb is then filled with a combustible metal suchas aluminum or magnesium wire 33. :I prefer to use finely chopped aluminum foilhavingna cross sectional area ofl mil square;

The bulb. portion is then forced over the base and interlocked by the rim l8 and groove II. A suitable cement 34 is then placed at the adjoining edges or the bulb and base portions, and this cement may be covered in turn it it is desired, by an additional lacquer coating 35. The interlocking joint takes all the strain and leaves to the cement and lacquer the sole job or making the joint vacuum tight. The atmosphere is then removed from the lamp through the tubulation 2| and replaced with an active combustion supporting gas such as oxygen.

I prefer to insert oxygen at distinctly more than atmospheric pressure, and have found that a pressure of 120 to 150% of atmospheric pressure produces a satisfactory flash in combination with the combustible metal and igniting means. In case higher pressures are desired, I increase the wall thickness of the bulb up to 100 mils or more.

The tubulationfl is then sealed off by two more.,meta1 surfaces similar to 30 and 3!, and the excess tubulation cut oil? by the knives 36, as illustrated in Figure 6. A suitable socket connection can then be applied to the lamp. As disclosed in Figur 2, a cylindrical casing 40 of brass fits tightly over the base projection 20 after one of the conducting standards 22 has its end bent over between the projecting base 20 and the metal wall 40.

The overlapping tip ll of this connection is soldered to the outer wall of the cylindrical casing. The other end 42 of the other connectin wire 23 extends to a metal contact cap 43 embedded in insulation 44 in an opening at the bottom of the metal casing 40. The metal casing 40 may have the projecting lugs 45 for retaining the lamp in its socket until flashed.

If desired screw threads may be placed in the metal casing 40 if a screw threaded socket is to be utilized. Other types of socket connections can also be provided, as illustrated in Figure '7, where one of the connecting standards 46 passes through the bottom projecting tube I! used for tubulation and then sealed off at 48.

The wire issecured to a metal cap 49 at the top end or the sealed oi! tubulation 41. The other connection or standard 50 passes through the casing to one side 01 the central tabulation l1 and is attached to a conductive band surrounding the tubulation 41. Various other types of connections can obviously be made to the ig-' niting means in the interior of the lamp.

when photoflash lamps, utilizing an organic plastic as a casing, were utilized, the heat sometimes concentrated near the plastic casing with a resulting volatilization of some or the or anic constituents of the plastic envelope. These volatile compounds burn in the oxygen atmosphere, thereby reducing the oxygen availabl 'ior buming the aluminum or magnesium metal in the lamp. These volatile organic compounds would then break down with a resulting heavy deposit of carbon on the inside or the envelope. The deposit of carbon. or course, tended to reduce the light output or the lamp.

My inside coating or a transparent inorganic material, such as sodium silicate, acts as a heat insulator, preventing the burning metal from coming into direct contact with the organic plastic material or the envelope. The complete combustion or the aluminum or magnesium charge of the photoflash lamp is, accordingly, permitted with a corresponding increas in light output. This coating, while preferably sprayed on the surface, can also be placed thereon by flushing a solution or sodium silicate on the surface and then permitting it to dry.

It is apparent that many modifications may be made in my invention and, accordingly, I desire only such limitations to be imposed thereon as is necessitated by the spirit and scope or the following claims.

I claim:

1. A photoflash lamp casing subject to severe internal explosive pressure in use and comprising a base portion and a bulb portion or translucent organic plastic or a thickness to be selfsupporting and an interlocking joint between said base and bulb portion, the edge or said bulb portion being compressed within said base portion and thereby obtaining increased retentive grip between the bulb portion and base portion with increase of pressure within the lamp in excess of external pressure.

2. A photoflash lamp casing subject to severe internal explosive pressure in use and comprising a translucent plastic bulb portion, and a base portion having a rim overlapping the edge of said bulb portion, said bas portion having an interior peripheral groove therein and the bulb portion having a peripheral bead facing said groove and forming an interlocking joint therewith and thereby obtaining increased retentive grip of the interlocking joint with increase or pressure within the lamp in excess of external pressure.

3. A photoflash lamp casing subject to severe internal explosive pressure in use and comprising a translucent plastic bulb portion, a base portion having a rim overlapping the edge oi said bulb portion, said base portion having an interior peripheral groove therein and the bulb portion having aperipheral bead facing said groove and forming an interlocking joint therewith and thereby obtaining increased retentive grip of the interlocking joint with increase of pressure within the lamp in excess 01' external pressure, and cement between and at the exterior or said rim and edge thereby sealing the joint to admissionoi air to the bulb while the internal pressure is less than external pressure.

4. In a lamp provided with a radiation-permeable envelope having a neck or material oi the character or organic plastic depending therefrom, a base secured on said neck and providing space between the bottom or the neck and bottom 01 the base, lead-in support wires for a fllament extending through the bottom or said base and having flattened areas in the portion thereof where passing through the plastic material, and pressure-sealed thereat by pressure applied normal to the flattened areas thereby obtaining intimate and tight sealing engagement of the pisstic on the lead-in wires.

5. In a lamp provided with a radiation-permeable envelope having a neck 01' material of the character or organic plastic depending therefrom, a base secured on said neck and providing space between the bottom or the neck and bot tom of the base, lead-in support wires for afllament extending through the bottom or said base and having flattened areas in the portion thereof where passing through the plastic material.

the bottom or said neck having nipples thereon I surrounding the said flattened areas oi the leadin wires, and pressure-sealed thereat by pressure applied normal to the flattened areas thereby obtaining intimate and tight sealing engagement of the plastic on the lead-in wires.

/ RAYMOND LE ROY KREIDIJR.