US2245794A - Photoflash lamp - Google Patents

Description

J. H. KURLANDER ET AL :PHOTOFLASH LAMP June 17, 1941.

Filed Jan. 26, 1939 Patented June 17, 1941 PHOTOFLASH LAMP John H. Kurlander, Nutley, and Raymond Le Roy Kreidler, Bloomfield, N. J., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application January 26, 1939, Serial No. 252,882

4 Claims.

The present invention relates to photoflash lamps and has particular reference to such lamps as utilized for photographic purposes.

A lamp of this type is Well known in the art wherein a material readily combustible with oxyness of approximately .0005 mm., which metals .i

are readily oxidizable upon ignition due to the gas filling within the vessel consisting of oxygen, an oxygen-gas mixture, or a gas which readily gives off oxygen. The metal foil or wire may consist of metals, metal alloys and rare earth metals, such as aluminum, copper, iron, nickel, phosphor-bronze, cerium, zirconium, magnesium, and also organic substances which are placed in the vicinity of the igniter.

Upon the passage of an electric current through the igniter there results an intense flash of light of approximately ,4 to 0 of a seconds duration caused by the combustion of the metal foil or wire in the presence of oxygen. The pressure of the gas within the envelope, being less i than atmospheric or approximately 350 mm. of mercury before combustion, is raised substantially instantaneously to a much higher pressure due to the generation of heat during combustion.

This increase of pressure is accordingly imposed upon the interior of the glass envelope and thus increases the risk of bursting of the bulb.

As the bulb is weakest at the point of seal thereof, the possibilities of bursting at such point is greatly enhanced due to this increase of pressure as well as the hot products of combustion being deposited at the point of seal.

It is accordingly an object of the present invention to provide a photoflash lamp wherein a baffle is provided to protect the neck and point of seal of the envelope from the increased gas pressure resulting from the combustion.

Another object of the present invention is to provide a photoflash lamp wherein a non combustible bafile is utilized which is yieldable so as is to absorb the shock caused by the sudden increase in gas pressure within the bulb, so that the increased pressure and the hot products of combustion are prevented from deleteriously affecting the neck and seal of the bulb and bursting the same.

Another object of the present invention is the provision of a heat deflecting non-combustible bafile disposed in the envelope between the combustible material and the neck and seal of the bulb which is yieldable' to absorb the sudden increase in gas pressure caused by combustion, so that the baffle more firmly engages the walls of the bulb and prevents the increased gas pressure and the hot products of combustion from passing through the neck and seal of the bulb, which might otherwise cause bursting thereof.

Still further objects of the present invention will become apparent to those skilled in the art by reference to the accompanying drawing wherein:

Fig. 1 is an elevational view showing a photoflash lamp wherein a 'yieldable bafile is employed in accordance with the present invention;

Fig. 2 is a cross-sectional View taken on the line IIII of Fig. 1;

Fig. 3 is a fragmentary cross-sectional view of a portion of the photoflash lamp illustrating the position of the yielclable baffle in such lamp;

Fig. 4 is a plan view of the non-combustible yieldable baiiie immediately following its fabrication and prior to its insertion into the photoflash lamp as shown in Fig. 1;

Fig. 5 is a fragmentary View of a photoflash lamp, such as shown in Fig. 1, and illustrating a slight modification which the non-combustible and yieldable baflie may take;

Fig. 6 is another fragmentary view of a photoflash lamp, such asshown in Fig. 1, and showing another modification wherein a pair of baffles are utilized, and

Fig. '7 is a fragmentary view of a photoflash lamp, such as shown in Fig. 1, wherein a still further modification of the non-combustible and yieldable baffle is shown.

Referring now to the drawing in detail, a photoflash lamp is shown. in Fig. 1 having the configuration of the usual incandescent electric lamp which comprises a bulb 5 provided with a neck portion 6. A reentrant stem 1 protrudes interiorly of the bulb and is sealed thereto at 8.

In order to transmit electrical current to an igniter or heater element 9, a pair of leading-in wires Ill and I2 extend through the reentrant stem 1 and are rigidly sealed therein by means of a press I3 which also serves to close the end of the reentrant stem 1. The bulb 5 is provided with a suitable base M, such as the customary metallic threaded base as used with incandescent lamps.

A sealed-in small tube I5 is positioned interiorly of the reentrant stem and at its upper end opens into the interior of the bulb at l6 for the purpose of exhausting the bulb and introducing the desired gaseous mixture, after which its free end is sealed 01f, as at ll. The envelope 5 is provided with a suitable combustible material,

such as magnesium wire, or, as shown, a plurality of leaves or sheets of metallic foil l8, such as aluminum, which are disposed in the vicinity of the igniter 9 within the bulbous portion of the envelope 5.

When an electric current is passed through the leading-in wires l and i2 and the igniter 9, combustion of the metallic foil l8 in the oxy enic atmosphere immediately follows with an intense flash of light. The interior of the bulb is coated with a suitable coating, such for example as cellulose acetate 59, for the purpose of preventing the hot products of combustion from contacting the glass and causing a bursting of the same.

During the process of sealing-in the reentrant stem '1, this coating in the neck of the bulb is usually burned off, thus normally exposing the glass portion of the neck to the hot aluminum oxide or unburned aluminum, as well as the sudden increase in gas pressure caused by combustion. In order to prevent a sudden increase in gas pressure, together with the hot products of combustion, rom coming in contact with the uncoated neck portion of the bulb or accumulating in the vicinity of the seal 3, a non-combustible bafiie 29 is provided.

This bafiie, which is shown more clearly in Fig. 4, may be stamped out of a suitable noncombustible material, such as sheet asbestos or the like, and as shown is provided with an elongated or elliptical opening 22 near its center which corresponds substantially to the crosssectional area of the press 13 formed upon the reentrant stem 1. In addition, the center portion of the bafile is provided with perforations 23 and extending radially adjacent the periphery of the bafile 25 are a plurality of slits 2d.

The diameter of the stamped or otherwise fabricated bafile is appreciably greater than the diameter of the neck portion 6 of the envelope 5, and in order to insert the balile interiorly of the envelope 5, the edge of the baffle is folded for the length of the slits 24 and, after filling the envelope with the combustible material l8, the press portion l3 of the stem 1 is inserted into the elliptical opening 22 on the bafile,

The mount assembly comprising the reentrant stem 1, together with the igniter element 9, is inserted into the open neck portion of the envelope with the folded edges of the bafile overlapping so as to decrease the diameter and enable the baffle to be inserted interiorly of the envelope to a point where, due to the resiliency of the bafiie material, it expands into contact with the wall of the envelope. The mount assembly is then drawn slightly downward to cause the angularly extending folded edge portions of the bafile to firmly engage the wall of the envelope, after which the mount is sealed to the envelope 5 at the point 8, as is well known in the art.

Upon the passage of an electrical current through the igniter element 9, combustion of the combustible material i8 results, together with a momentary flash of intense light, which moment of flash is usually synchronized with the complete opening of a camera shutter so as to expose a sensitized film. Simultaneously with the combustion, and due to the increase in temperature, the pressure of the gas within the envelope is suddenly increased so that it rises substantially above atmospheric pressure, with the gas naturally expanding within the envelope.

In addition, the hot products of combustion gravitate and, since the photofiash lamp is usually employed in an upright position, the expancombustion would normally pass downwardly of the envelope in the vicinity of the neck portion 6. Inasmuch as the coating [9 is usually fired off of the neck portion during the sealing-in process, such hot products have heretofore contacted the uncoated neck portion and also the seal portion 8, which is the weakest part of the envelope, frequently resulting in bursting of the envelope with possibility of danger to the photographer or persons in the vicinity of the flash lamp.

However, since the baffle 26 is supported by the press portion I3 of the reentrant stem 1. and the edge of the baffle firmly engages the wall of the envelope 5, the expanding gas as well as the hot products of combustion are prevented from passing into the neck portion 6 of the envelope 5, thus eliminating the danger previously existent in photoflash lamps.

Moreover, since the bafile 29 is of a non-combustible material, such as sheet asbestos or the I like, which by its nature is yieldable, such baille sion of the hot gases and the hot products of absorbs the shock caused by the increase in the gas pressure and, since the sudden increase in gas pressure will be imposed upon the greatest surface area of the baffle thus tending to force the same downwardly, the effect is to cause the edge of the ballie to be wedged more firmly against the side wall of the bulb, thus automatically increasing the effectiveness of the seal accordingly formed and preventing the hot products of combustion from passing into the neck portion 6.

In order to prevent the increased gas pressure from being confined too much to the bulbous portion of the envelope 5, the bafiie 29 is provided with perforations 23, as before noted, which allows the expanding gas to pass into the neck portion 6 of the envelope. However, due to the diameter of the perforations, the expanding gas is effectively retarded so that the pressure within the neck portion 5 is gradually increased as compared with the increase within the bulbous portion, with the result that while the pressure after a brief moment equalizes throughout the envelope, it nevertheless is precluded from being too suddenly imposed upon the neck portion 6 of the bulb which is the weakest part because of the thinness of the glass, the strains therein from sealing-in and basing, and the firing off or deficiency of the protective coating is, as hereinbefore mentioned.

It should also be noted that if the diameter of the baflle 2B is too small, the force of the increase in pressure may blow one side of the baflle downwardly, thus making an opening of sufficient size to permit the hot products of com bustion to strike the weak neck portion and possibly rupturing it. However, by constructing the bafile in the manner noted wherein the diameter is much greater than that of the neck portion 6 and the edgeportions are so folded as to overlap and angularly extend into frictional engagement with the envelope wall, blowing down of the edges of the baille is precluded and in lieu thereof the edges are caused to more firmly engage the wall due to the increased gas pressure.

If desired, the center section of the baflle, that is, that portion which is disposed transversely of the longitudinal axis of the envelope 5, when in position therein, may be reinforced, such as shown in the modification of Fig. 5, which reinforcing assures that the baflle will withstand the increased gas pressure when the lamp is flashed, thus more or less restricting the yieldability of the baiile 20 to the angularly extending edges rather than the flat center section.

Also, in lieu of the baffle 20 having a reinforcing'center section, such as shown in Fig. 5, a double baffle, as shown in the modification of Fig. 6, may be employed. In this modification the baflie 2t surrounds the press portion l3 as described in the previous modifications. The additional baflle 25 is thus disposed above the baffle 29 and held in contact with the extremity of the press portion l3 by the leading-in conductors l and I2.

As a still further modification, the baflle 20 may be of a funnel shape, such as shown in Fig. 7. Here again, however, the surface area of the bafile 20, which is subjected to the sudden increased gas pressure, is such that as the wall of the funnel tends to expand due to the pressure, the edge which is in contact with the wall of the bulb is nevertheless forced more firmly into frictional engagement with the Walls in the same manner as previously described with respect to the other modifications.

It thus becomes obvious to those skilled in the art that a photofiash lamp is herewith provided wherein a cup-shaped non-combustible battle is employed which is yieldable upon the sudden increase in gas pressure within the bulb due to combustion of the oxidizable material which results in the edge of the baflle being wedged more firmly against the bulb wall, thereby forming a barrier which prevents the sudden increased gas pressure and the hot products of combustion from passing into the vicinity of the neck and seal portion of the bulb, thus eliminating the possibility of bursting of the lamp.

Although several embodiments of the present invention have been shown and described, it is to be understood that still further modifications of the same may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

1. A photofiash lamp comprising a sealed gastight transparent bulb provided with an oxygenic atmopshere therein, an oxidizable material disposed in said bulk which is readily combustible with oxygen for producing an intense momentary actinic efiect, an igniting element disposed interiorly of said bulb in proximity to said oxidizable material for causing combustion of the latter with the oxygen in said bulb when electrical energy is supplied to said igniting element, and a heat deflecting bafiie disposed in said bulb of a non-combustible material and provided with upwardly extending wall portions with the edge thereof in frictional engagement with the wall of said bulb and yieldable upon an increase in gas pressure following combustion of said oxidizable material to cause the upwardly extending wall portions to more firmly engage the wall of said bulb to prevent the sudden increase in gas pressure and the hot products of combustion from deleteriously affecting the neck and seal of said bulb.

2. A photo-flash lamp comprising a sealed gastight transparent bulb provided with an oxygenic atmosphere therein, an oxidizable material disposed in said bulb which is readily comibustible with oxygen for producing an intense momentary actinic eifect, an igniting element disposed interiorly of said bulb in proximity to said oxidizable material for causing combustion of the latter with the oxygen in said bulb when electrical energy is supplied to said igniting element, and a heat deflecting non-combustible bafile disposed in said bulb between said oxidizable material and the seal of said bulb and provided with up Wardly extending wall portions with the edge thereof frictionally engaging the wall of said bulb, said baffle having a reinforced perforated center section and being yieldable upon an increase in gas pressure following combustion of said oxidizable material to cause the upwardly extending wall portions to more firmly engage the wall of said bulb and to enable the gradual expansion of the gas through said perforations for the purpose of preventing the increase in pressure from being too suddenly imposed upon the neck and seal of said bulb and for preventing the hot products of combustion from accumulating in the vicinity of the seal and neck of said bulb.

3. A photofiash lamp comprising a sealed gastight transparent bulb provided with an oxygenic atmosphere therein, an oxidizable material disposed in said bulb which is readily combustible with oxygen for producing an intense momentary actinic effect, an igniting element disposed interiorly of said bulb in proximity to said oxidizable material for causing combustion. of the latter with the oxygen in said bulb when electrical energy is supplied to said igniting element, and a cup-shaped non-combustible bafile disposed transversely of the longitudinal axis of said bulb between said combustible material and the neck and seal of said bulb and provided with an angularly disposed upwardly extending edge frictionally engaging the wall of said bulb to render said baffle yieldable upon an increase of pressure following combustion of said oxidizable materal to prevent the sudden increase in gas pressure and the hot products of combustion from passing to the vicinity of the neck and seal of said bulb and deleteriously affecting the same.

4. A photofiash lamp comprising a sealed gastight transparent bulb provided with an oxygenic atmosphere therein, an oxidizable material disposed in said bulb which is readily combustible with oxygen for producing an intense momentary actinic effect, an igniting element disposed interiorly of said bulb in proximity to said oxidizable material for causing combustion of the latter with the oxygen in said bulb when electrical energy is supplied to said igniting element, and a cup-shaped non-combustible baiile disposed transversely of the longitudinal axis of said bulb between said combustible maetrial and the neck and seal of said bulb and provided with an angularly disposed upwardly extending edge frictionally engaging the wall of said bulb having a plurality of slits to enable overlapping thereof and yieldable upon an increase of pressure following combustion of said oxidizable material to prevent the sudden increase in gas pressure and the hot products of combustion from passing to the vicinity of the neck and seal of said bulb and deleteriously affecting the same.

JOHN H. KURLANDER. RAYMOND LE ROY KREIDLER.

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