US3706521A - Flashlamp - Google Patents

Abstract

A percussive-type flashlamp has a glass envelope, a metal base sealed to one end and having a cup portion extending from it, with an anvil fitted into said cup by crimping or the like, the anvil having a cylindrical portion terminating at one end in a flat annular rim seated at the flat bottom of the cup and having a concave portion to form an enclosed cavity with said flat bottom of the cup. This construction provides a rigid anvil which will hold firm against the action of the firing pin, and which forms a cavity for a percussive charge, the opposite flat portion of the cavity being held with a precise spacing between them. The end of the cylindrical portion of the anvil terminates in a flaring shield which spreads out to the inner diameter of the envelope to protect the metal base from molten metal particles, or agglomerates of particles, from the foil of shredded metal, for example of zirconium, with which the envelope is filled. There is also a filling of oxygen at high pressure in the envelope, which is sealed.

Description

United States Patent Kopelman et al.

[ FLASHLAMP [7 2] Inventors: Bernard Kopelman, Salem; Warren H. Hay, Beverly, both of Mass.

[73] Assignee: Sylvania Electric Products, Inc.

[22] Filed: April 6, 1971 211 Appl. No.: 131,802

Related US. Application Data [63] Continuation of Ser. No. 662,755, Aug. 23, 1967,

FOREIGN PATENTS OR APPLICATIONS 431,953 7/1935 Great Britain ..43l/93 Primary Examiner-Edward G. Favors Att0rneyNorman J. OMalley and Laurence Burns [57] ABSTRACT A percussive-type flashlamp has a glass envelope, a metal base sealed to one end and having a cup portion extending from it, with an anvil fitted into said cup by crimping or the like, the anvil having a cylindrical portion terminating at one end in a flat annular rim seated at the flat bottom of the cup and having a concave portion to form an enclosed cavity with said flat bottom of the cup. This construction provides a rigid anvil which will hold firm against the action of the firing pin, and which forms a cavity for a percussive chargefthe opposite flat portion of the cavity being held with a precise spacing between thcm. The end of the cylindrical portion of the anvil terminates in a flaring shield which spreads out to the inner diameter of the envelope to protect the metal base from molten metal particles, or agglomerates of particles, from the foil of shredded metal, for example of zirconium, with which the envelope is filled. There is also a filling of oxygen at high pressure in the envelope, which is sealed.

3 Claims, 1 Drawing Figure 1 m 2 M 5 H Y 6 PA 0 OH K 7 DH 3 R A m 3 H BW INVENTORS ATTORNEY PATENTED llEc 19 I972 FLASHLAMP This application is a continuation of application Ser. No. 662,755 filed Aug. 23, 1967 and now abandoned.

FIELD OF INVENTION This invention relates to photographic flashlarnps and the like of the type fired by the action of a firing pin on a percussive detonator, thereby eliminating the need for the electric battery used with the prior type of commercial flashlamp.

DESCRIPTION OF PRIOR ART In the percussive type lamp, an envelope of lighttransmitting glass is sealed at one end to a cup, usually of metal, which closes off one end of the tube and supports an anvil which fits on the bottom of the cup, leaving space for the percussive charge. The glass envelope has a filling of the usual shredded foil or the like, generally of zirconium metal. In operation, when the outside cup is struck by a firing pin, the percussive charge is forced against an anvil and detonates, heating up numerous particles of metal, such as zirconium, which are mixed with it, and shooting them through holes in the anvil into the shredded foil or the like, setting it off to burn in the oxygen with which the envelope is filled to a high pressure.

SUMMARY OF THE INVENTION The metal base which sealed off the bottom of the glass tube should be easily deformable by a firing pin so that a large part of the energy of the pin is available to set off the percussive material; moreover, the base should also be capable of being sealed to a glass envelope with a minimum of strain and with sufficient strength to withstand the normal high fill gas pressure as well as the very high pressure built up during the flash; and it should be capable of being easily fabricated at low cost on high speed machinery.

We have discovered that such a base can be made of the so-called No. 4 alloy metal for scaling to soft glass, although any metal which can be sealed with a strong bond to the glass can be used and if sufficiently deformable would be suitable. The cup is in a shape having an open rim for sealing to the glass, the rim having a taper narrowing toward the open end forming a frustrum of a cone and terminating at its other end on a flat, annular portion from the center of which a cylindrical cup extends downwardly to be closed by a substantially flat closure member, generally integral with the cup. The tapered rim insures good contact with the glass. The flat closure member is the portion of the base to be struck by the firing pin and the flat surface lies parallel to the flat anvil to be described. The percussive material is confined between these surfaces.

The anvil, which can be of metal, is inserted into the cup. We have discovered that the anvil can be flat in its effective region rather than pointed, in order to allow for greater variation in the striking position of the firing pin, but the spacing between the anvil and the bottom of the cup must be held very uniformly from lamp to lamp to lamp. The bottom of the anvil should have some holes through which the hot metal particles from the percussive mixture may travel upwardly to set off the shredded zirconium foil, or similar material. We have discovered that the smaller these holes are made the smaller is the likelihood of molten zirconia globules, from burning shreds, burning through the bottom of the metal base.

We have further discovered that these hot globules can burn through the metal of the base around the anvil, and that this can be prevented by flaring out the open end of the cylindrical portion of the anvil until it extends substantially to the inside of the envelope wall, to form a shield between the shredded metal foil and the metal base. The shield should be capable of being slipped into the inside of the envelope, which is tubular.

We have found that the anvil must be held rigidly and not deform much from the energy of the striking pin.

We have discovered that these results can be achieved by an anvil having its bottom portion concave, with a flat rim, and a cylindrical portion extending backwardly from the rim, the other end of the cylindrical portion being flared out to act as a shield for the cup. The concave nature of the anvil increases the resistance of the piece to deformation by the pin, and by making the central portion of the concavity flat, while the rim of the anvil seats on a flat portion of the cup, the distance between the bottom of the cup and the flat top of the cavity is fixed, and the spacing does not depend on the precision of the person or mechanism attaching the cup and anvil together.

In addition, the anvil so made can be of thinner metal because of the shorter span of the concavity. This, in turn, allows the holes in the anvil to be punched, rather than drilled, and they can consequently be made much smaller.

If it is desired to insure still further against any burn through of the metal cup from the hot' particles of metal, a copper or nickel wafer can be placed at the bottom of the metal cup and held in place by the rim of the anvil.

The cylindrical portions of the cup and the anvil can be held together by crimping.

BRIEF DESCRIPTION OF DRAWING Other features, advantages and objects of the invention will be apparent from the following specification, taken with the attached drawing in which:

The Figure is a cross-sectional view of a flashlamp embodying the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS In the Figure, the glass envelope 1 is sealed at its otherwise open end 2 to a metal base 3 having an inwardly-flared rim 4 which engages the glass envelope. The base has a flat annular portion 5 and a convexly protruding cup 6 with a flat bottom 7. Resting on this bottom 7 is the rim 8 of the anvil 9, said anvil having a concave portion 10 with slanting or curved sides extending inwardly from the rim of the anvil as a whole, to terminate in a substantially flat portion 11. The cylindrical surface 12 of the anvil fits into the cup 6 and the two are crimped together at 13.

The anvil is thus rigidly held to the cup 6 and the distance between the flat bottom 7 of cup 6 and the flat top 11 of anvil 9 is fixed. The rim 8 of the anvil being flat and in contact with the flat bottom 7 of cup 6 confines the percussive mixture 14 to a small volume at the center of the cup, which reduces the amount of the mixture needed and keeps it in a confined space, thereby getting full effect from it.

The flared-out shield at the top of anvil 9 extends outwardly and upwardly to shield the seal from hot metal particles which might otherwise hit it with deleterious effect.

The shredded foil 16 is the usual material with which modern flashbulbs are filled, for example, shreds of zirconium. The envelope 1 is filled with oxygen at a high pressure, say about 6 atmospheres, in the usual manner, the envelope being sealed off at the exhaust tube 17 at the top of the envelope 1.

ln using the words top and bottom" with reference to the device of this application, we mean top and bottom as in the drawing, that is, with the device held with the base 3 down and the exhaust tip 17 in a vertical direction. I

The anvil 9 has a number of holes in its fiat surface, so that when the percussive mixture is set off, hot particles of metal will be shot through the holes to reach the shredded foil 16 and set it off.

In one embodiment of the invention, the anvil 9 was of 0.010 inch metal stock, the cylindrical portion being about 0.145 inch outside diameter and about 0.155 inch in length. The open portion was fiaredvto a radius of about one-sixteenths inch, the outside diameter of the flare being about 0.285 inches. The glass envelope was a tube about 0.290 inches inside diameter, and 0.350 inches outside diameter, sealed at one end by an exhaust tube. The length from the rounded top of the envelope, exclusive of the exhaust tip, to its open end was about 1 inch.

The base had a maximum outside diameter of about 0.400 inches, with the open end tapering to about 0.356 inches, the cup having an inside diameter of about 0.146 inches, with the outside length of the cup being about 0.150 inches.

The anvil 9 can be made of low carbon steel or other suitable material. The No. 4 alloy mentioned above as a material of which the base 3 can be made is well-known in the art for sealing to the soft lead glass, generally known as 6-1 glass, of which the envelope 1 can be made. No. 4 alloy is a nickel-chromium steel of about 42 percent nickel, 6 percent chromium and the remainder iron.

Various modifications will be apparent to a person skilled in the art without departing from the spirit and scope of the invention, and the invention is not limited to the specific embodiment described, but is set forth in the claims.

A suitable percussive mixture is that shown in a patent application Ser. No. 662,756 of B. Kopelman and D. Seeger for a Photoflash Lamp and Composition therefor, filed Aug. 23, 1967 now abandoned.

We claim:

l. A percusive-type flashlamp comprising a glass envelope sealed at its otherwise open end to a metal base closingit, said base having a cup extending outwardly therefrom, an anvil in said cup defining therewith a cavity in which percusive material can be placed, said anvil having a flat rim fitting against the bottom of said cup and a concave portion with a flat top portion inside said rim, and percusive material in said cavity, and in which the anvil includes a metal cylinder having one end closed by said fiat annular rim with a concave tron inside said rim, said concave portion having a t lz tt inner span, and a flared portion extending upwardly and outwardly from the metal cylinder toward the side of the glass envelope.

2. A percusive-type flashlamp having a metal base, an enclosing transparent envelope afixed thereto, a filling of metal shreds in said envelope, and an anvil therein, and a metal shield, said shield being flared from the anvil to a diameter nearly as great as the inside diameter of the envelope, to protect the metal base from molten metal particles from the filling.

3. A percusive-type flashlamp comprising a glass envelope sealed at its otherwise open end to a tubular metal piece closing it, a filling of metal shreds in said envelope, and an anvil in said metal piece, said anvil having a shield above said tubular piece and in position to shield said piece from molten metal particles from the filling.

Claims (3)

1. A percusive-type flashlamp comprising a glass envelope sealed at its otherwise open end to a metal base closing it, said base having a cup extending outwardly therefrom, an anvil in said cup defining therewith a cavity in which percusive material can be placed, said anvil having a flat rim fitting against the bottom of said cup and a concave portion with a flat top portion inside said rim, and percusive material in said cavity, and in which the anvil includes a metal cylinder having one end closed by said flat annular rim with a concave portion inside said rim, said concave portion having a flat inner span, and a flared portion extending upwardly and outwardly from the metal cylinder toward the side of the glass envelope.

2. A percusive-type flashlamp having a metal base, an enclosing transparent envelope afixed thereto, a filling of metal shreds in said envelope, and an anvil therein, and a metal shield, said shield being flared from the anvil to a diameter nearly as great as the inside diameter of the envelope, to protect the metal base from molten metal particles from the filling.

3. A percusive-type Flashlamp comprising a glass envelope sealed at its otherwise open end to a tubular metal piece closing it, a filling of metal shreds in said envelope, and an anvil in said metal piece, said anvil having a shield above said tubular piece and in position to shield said piece from molten metal particles from the filling.

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