Title:
PHOTOFLASH DEVICE
United States Patent 3739166
Abstract:
A photoflash device with a photoflash lamp mounted within a reflector, the lamp being mountable in the reflector only in one or the other of two 180° apart axially oriented positions, has only one moisture indicator spot so located on the inside wall of its transparent envelope as to be viewable from in front of the reflector either directly or by reflection off the reflector irrespective of which one of the axially oriented positions the lamp is mounted in within the reflector.


Inventors:
ANDERSON R
Application Number:
05/214246
Publication Date:
06/12/1973
Filing Date:
12/30/1971
Assignee:
General Electric Company (Schenectady, NY)
Primary Class:
International Classes:
G03B15/04; (IPC1-7): G03B15/02
Field of Search:
240/1.3 95
View Patent Images:
US Patent References:
3609331PHOTOFLASH LAMPSeptember 1971Fink et al.
3597602PHOTOFLASH REFLECTOR SUITABLE FOR FLASHCUBEAugust 1971Divoky et al.
2993008Moisture indicator for photoflash lampJuly 1961Anderson
2726527Flash lampDecember 1955Pipkin
Primary Examiner:
Matthews, Samuel S.
Assistant Examiner:
Braun, Fred L.
Claims:
What I claim as new and desire to secure by Letters Patent of the United States is

1. In a photoflash device comprising a base, a reflector positioned with respect to said base, and a photoflash lamp mounted on said base adjacent the innermost region of said reflector, said photoflash lamp including an elongated light-transmitting envelope disposed with its longitudinal axis extending transversely to the reflector axis of symmetry, said lamp being mountable on said base in either one of two positions spaced 180° apart about its longitudinal axis, said lamp being mountable on said base, in each of said positions, with its longitudinal axis in a mounting plane disposed approximately normal to the reflector axis, the combination therewith of a single spot of a moisture indicating material on the inside wall of said envelope, said indicator spot being located with its center on a line passing through the longitudinal axis of said envelope and extending at an angle of approximately 30° to either side of said mounting plane in each of said two positions whereby the indicator spot is visible from in front of the reflector either directly or as a reflected image off the reflector irrespective of which one of the said two positions the lamp is mounted in relative to the reflector.

2. A photoflash device as set forth in claim 1 wherein the said reflector is formed with a lamp-receiving tunnel at its innermost region within which the said envelope of the lamp is nested to a depth around 20 to 30 percent of its diameter.

3. A photoflash device as specified in claim 1 wherein a plurality of said photoflash devices are mounted adjacent one another.

4. A photoflash device as specified in claim 1 including four of said devices located adjacent one another, with adjacent ones of said devices mounted at right angles to each other and with their said reflectors facing outwardly to form four sides of a cube.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to photoflash devices comprising a photoflash lamp mounted within a reflector, and more particularly to such a device having a single moisture indicator spot on the inside wall of the lamp envelope.

2. Description of the Prior Art

Certain types of flash lamps in use at present, particularly those of miniature size such as that commonly referred to as AG-1 type flash lamps, are for the most part fixedly assembled in place within a cooperating miniature size reflector to form a combination lamp-reflector unit or assembly. Several of these lamp-reflector assemblies are commonly mounted adjacent one another to form a multiple flash lamp array of which the conventional flashcube is one well-known embodiment. Linear arrays of such flash lamp-reflector assemblies are also well-known in the art.

To provide the flash lamp manufacturer as well as user with a readily visible indication as to the operative condition of the lamp, i.e., whether or not any atmospheric air has leaked into the lamp such as would adversely affect its flashability, it has been customary practice to provide an indicator spot of a so-called chemical leak detector material on the inside wall of the lamp envelope which undergoes a change in color in the event contaminating atmospheric air along with the water vapor normally contained therein should penetrate into the interior of the envelope. The complex salt cobaltous-cobaltic cyanide is particularly effective for such purpose. In the anhydrous state, such a salt is blue; in the hydrated state, the salt is pink. However, because each of the flash lamps in the aforementioned flashcube array, as well as in most other multiple flash lamp arrays, are generally mounted in one or the other of two predetermined axially oriented positions 180° apart within the associated reflector, it has been customary heretofore to employ two such indicator spots located diametrically opposite one another on the envelope wall and spaced therearound approximately 90° from the axial mounting plane of the lamp so that no matter which of the two 180° apart oriented positions the lamp is mounted in within the reflector, one or the other of the indicator spots of the lamp envelope will always face outwardly of the reflector so as to be exposed to the view of one examining the lamp. It was reasoned that the provision of two such diametrically opposed indicator spots on the lamp envelope would thus eliminate the need for orienting and mounting the lamp in only one predetermined axially oriented position within the reflector -- an operation that would be time-consuming and very difficult to perform on the automatic high operating speed production equipment conventionally employed to manufacture such flashcube assemblies. But the provision of two indicator spots on each lamp envelope instead of one obviously entails the drawback of doubling the amount and thus the cost of the indicating material employed in the manufacture of the lamps and also introducing an extra indicator spot application step into the overall lamp manufacturing procedure.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a flash lamp and reflector assembly having only one moisture indicator spot on the inside wall of the flash lamp envelope which is visible from the front of the reflector either directly or by reflection off the reflector irrespective of which one of two 180° apart axially oriented mounting positions of the lamp it is mounted in within the reflector.

Another object of the invention is to provide a multiple flash lamp array comprised of a plurality of adjacent flash lamp and reflector assemblies the individual flash lamps of which are each provided with only one moisture indicator spot which is visible from the front of the respective reflector either directly or by reflection off the reflector irrespective of which one of two 180° apart axially oriented mounting positions of the lamp it is mounted in within the respective reflector.

Briefly stated, in accordance with one aspect of the invention, the flash lamp of a combination flash lamp and reflector assembly of the type wherein the flash lamp is mountable in either one of two 180° apart axially oriented positions within the reflector, is provided with only one moisture indicator spot on the inside wall of the flash lamp envelope, the indicator spot being located within either one of two diametrically opposite arcuate extents of the lamp envelope, each centered relative to the axial plane of the lamp envelope extending transversely to the reflector axis whereby the indicator spot is visible from in front of the reflector either directly or by reflection off the reflector irrespective of which one of the two 180° apart axially oriented positions the flash lamp is mounted in within the reflector.

Further objects and advantages of the invention will appear from the following detailed description of a species thereof and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is an elevation on an enlarged scale of a photoflash device in the form of a flashcube embodying the invention, with the moisture indicator spot of the flash lamp being shown as directly visible.

FIG. 2 is a view similar to FIG. 1 but showing the flash lamp mounted instead in the flashcube reflector in a position rotated 180° from that of FIG. 1 and showing the moisture indicator spot visible as a reflected image off the reflector instead of directly as in FIG. 1.

FIG. 3 is an elevation on an enlarged scale of the flash lamp of the photoflash device comprising the invention, and

FIG. 4 is a sectional view on the line 4--4 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, the invention is there illustrated as embodied in a conventional flashcube comprising an array of four photoflash devices or combination flash lamp-reflector assemblies 1 each embodying the invention and mounted adjacent one another, with adjacent ones of the devices 1 mounted at right angles to each other and with their reflectors 2 facing outwardly to form four sides of a cube. Each flash lamp-reflector unit or assembly 1 is comprised of a miniature size flash lamp 3, such as that commonly referred to as an AG-1 type flash lamp, mounted within the innermost part of the associated reflector 2 which, as is customary, is of generally parabolic curvature. As shown in FIG. 3, the flash lamp 3 is comprised of a tubular shaped light-transmitting hermetically sealed glass envelope 4 which is formed at one end with an external flattened press seal portion 5. Sealed into the envelope 4 is a lamp mount structure 6 comprised of a pair of lead-in wires 7, 8 which are fixedly supported in spaced side-by-side relation by a glass bead 9 fused therearound. The lead-in wires 7, 8 are sealed through the flattened press seal 5 and extend outwardly in an endwise direction therefrom. An ignition filament 10 of tungsten or a tungsten-rhenium alloy is mounted within the envelope 4, the filament being connected across the inner ends of the lead-in wires 7, 8. Coatings 11 of a suitable primer material, such as an admixture of zirconium, magnesium and potassium perchlorate powders bonded together by a binder such as nitrocellulose, are provided on the inner tip ends of the lead-in wires 7, 8 and on at least the opposite end portions of the filament 10 where it connects with the lead-in wires. The envelope 4 contains a loosely distributed quantity 12 of a suitable light-producing filamentary combustible material such as, for example, a shredded foil of zirconium, aluminum or hafnium, together with a filling of a combustion-supporting gas such as oxygen at a suitable pressure up to as high as several atmospheres, e.g., 7 atmospheres or so. The envelope 4 is formed, at the end thereof opposite its press seal end 5, with an exhaust tip 13 left by the tipping off of a glass exhaust tubulation on the envelope after the evacuation and filling thereof through the exhaust tubulation with the combustion-supporting gas filling.

While the invention is illustrated as applied to flash lamp-reflector assemblies 1 employing flash lamps 3 of the so-called electrically ignited type having an ignition filament 10 which is adapted to be heated by the passage of an electric current therethrough from a battery or other source of electric power, it should be understood that the invention is applicable as well to flash lamp-reflector assemblies 1 employing flash lamps having various other type of lamp ignition means such as, for example, the percussively ignited type flash lamps which are employed in conventional percussive-ignited flashcubes in common use at present under the commercial designation "Magicube" and which are ignited by the striking of a hammer blow against a readily deformable metal ignition tube which contains a percussively ignitable primer or fulminating material and is sealed into and opens into the interior of the lamp envelope. Such percussively ignited type flash lamps are disclosed, for example, in U.S. Pat. No. 3,535,063, Anderson et al.

The reflectors 2 of each flash lamp-reflector assembly 1 may be constituted of preformed plastic sheet material having a light-reflective coating and defining an inwardly dished individual light reflecting surface 14 of suitable shape such as generally parabolic curvature, as is conventional in customary flashcube and other multiple photoflash lamp arrays. To enable the flash lamp 3 to be positioned within the innermost region of the reflecting surface 14 of the reflector 2 and contained more or less entirely within the confines thereof, the reflector 2 may be formed with a tunnel portion 15 at its innermost region for partially accommodating therein the tubular glass envelope 4 of the flash lamp, as shown in FIG. 4. The tunnel portion 15 extends all the way down to the bottom of the reflector 2 to form a shroud portion 16 at its lower end for accommodating therein the entire lower end portion of the flash lamp 3.

The photoflash device 1 may be provided with the customary base 17 made of a suitable synthetic plastic for mounting the device on a camera. In the case of the particular flashcube array illustrated employing flash lamps 3 of the electrically ignited type, the base 17 includes a platform support portion 18 of substantially square shape, with its edges bowed outwardly a slight amount, on which platform the orthagonally arranged array of reflectors 2 rest. The platform support 18 has a plurality of apertures through which the lead-in wires 7, 8 of the respective flash lamps in the array extend to the under side where they are bent around an annular contact ring or collar 19 integral with and depending from the under side of the platform support to form the electrical contacts 7', 8' for the individual flash lamps of the array. The base 17 is also formed with a center post 20 depending from the under side of the platform support 18 and terminating in a plurality of radially outward extending retaining lugs 21 adapted to engage with locking or clamping means in the flashcube-receiving socket of a camera to retain the flashcube in place in the socket. A transparent or light-transmitting cover or shield 22 of a single molded piece of a suitable synthetic plastic material such as polystyrene and of substantially cubic shape is disposed over the array of flash lamp-reflector assemblies 1 to provide a protection from possibly rupturing flash lamps in the array as well as to prevent direct touching of the lamps while they are still in their highly heated condition immediately following the flashing thereof. The cover 22 is permanently affixed at its bottom edge to the platform support 18 by suitable means as, for example, by an adhesive or by heat-sealing or ultrasonic welding.

In the illustrated flashcube array, and as is generally customary in most other type multiple flash lamp arrays such as linear type arrays, the individual flash lamps 3 are mounted in their associated reflectors 2 with the axis X--X (FIG. 3) of the lamp envelope 4 disposed transversely to the axis R--R (FIG. 4) of the reflecting surface 14 of the associated reflector 2, and with the lamp oriented about its axis to position the plane P--P (FIG. 4) of its flattened press portion 5 transversely to the reflector axis R--R. The mounting of each flash lamp 3 in such an axially oriented position in its associated reflector 2 serves to align the outer end portions of the lead-in wires 7, 8 protruding straight out from the press seal 5 of the lamp with the outer side wall of the contact ring 19 on the flashcube base 17 so that these protruding wire portions, during the flashcube assembly operation, can be threaded straight down through the apertures provided for them in the platform support 18 and will thus extend closely alongside the outer side wall of the contact ring 19 in position for bending therearound to form the lamp contacts 7', 8' thereon. It will be apparent, however, that there are two 180° apart axially oriented positions of the flash lamp 3 in which it can be mounted in the reflector 2 with the plane of its flattened press seal portion 5 disposed in the above-specified manner extending transversely to the axis R--R of the associated reflector 2.

It has been common practice in the flash lamp art to provide a small spot of a suitable chemical leak detector or moisture indicator material, such as the complex salt cobaltous-cobaltic cyanide, on the inside wall of the flash lamp envelope near the press seal end 5 thereof to indicate to a lamp viewer, by change of color, the presence in the envelope of water vapor that may have penetrated into the envelope from the ambient atmosphere and thus indicate to the user that the lamp is a so-called "leaker" and therefore will not flash properly. In the case of the flash lamp-reflector assemblies employed heretofore in flashcube arrays, two such moisture indicator spots have generally been provided on the inside wall of each flash lamp envelope, the two indicator spots being located on more or less diametrically opposite sides of the envelope and generally in that axial plane of the lamp extending normal to the plane P--P of the lamp press portion 5 and parallel to the reflector axis. The use of two such diametrically opposed indicator spots on the lamp thus eliminated the need for performing the time-consuming and difficult manufacturing operation of orienting and mounting the lamp in only one predetermined axially oriented position within the reflector since no matter which one of the two 180° apart axially oriented positions the lamp was then mounted in within the reflector 2, one or the other of the two indicator spots would always be facing outwardly of the reflector and thus exposed to the direct view of one viewing the flash lamp array.

In accordance with the invention, it has been found that by locating a moisture indicator spot 23 of the character described hereinabove within certain predetermined arcuate extents of the flash lamp envelope 4, only one moisture indicator spot 23 need be provided on the envelope of the flash lamp 3 mounted in the reflector 2 while still being visible to the viewer, either directly or by reflection off the reflector 2, irrespective of which one of the two 180° apart predetermined axially oriented mounting positions of the flash lamp it happens to be mounted in within the reflector 2 during the manufacture of the assembly 1. To this end, the single indicator spot 23 on the envelope 4 of a flash lamp 3 mounted in a reflector 2 is located within one or the other of those diametrically opposite arcuate extents "a" (FIG. 4) of the lamp envelope 4, centered on the lamp mounting plane P--P positioned tranversely of the reflector axis R--R, which extent approximately 60° around the lamp axis X--X, i.e., approximately 30° to either side of the lamp mounting plane P--P as indicated at "b." With such a located single indicator spot 23 on the flash lamp 3, the spot 23 will be visible to the viewer of the flash lamp-reflector assembly 1, either directly or by reflection off the reflector 2 from the front thereof, if the flash lamp 3 happens to be mounted, in the reflector 2 during the production manufacture of the assembly 1, in that axially oriented mounting position of the lamp in the reflector which results in the single indicator spot 23 facing outwardly of the reflector, as shown in FIG. 1 and in solid lines in FIG. 4. On the other hand, if the flash lamp 3 happens to be mounted in the reflector 2, during the production manufacture of the assembly 1, in that axially oriented mounting position of the lamp 3 which results in the single indicator spot 23 facing inwardly of the reflector 2, as shown in dotted lines in FIGS. 2 and 4, then in that case the indicator spot 23 will be visible to the viewer, from the front of the reflector, as a reflected image 23' off the reflector 2, as indicated in FIG. 2 and by the arrows 23" in FIG. 4. Thus, irrespective of which one of its two 180° apart axially oriented mounting positions in its mounting plane P--P the flash lamp 3 happens to be mounted in within the reflector 2, the single indicator spot 23 located on the envelope 4 in the manner according to the invention nevertheless will be clearly visible to the viewer of the flash lamp-reflector assembly 1 either directly, as shown in FIG. 1, or indirectly as a reflected image 23' off the reflector 2, as shown in FIG. 2. If the single indicator spot 23 is located on the envelope 4 a substantial distance beyond the prescribed approximately 30° limit to one or the other side of the mounting plane P--P of the flash lamp 3, then in that event the indicator spot 23 most likely would not be visible by reflection off the reflector 2 in the case where the lamp 3 is mounted in the reflector with its one indicator spot 23 facing inwardly thereof, the reflected image 23' of the indicator spot 23 in such case either being obstructed or blocked off from view by the outermost side portions of the flash lamp 3 itself, or else being reflected off the generally cylindrically curved wall of the tunnel portion 15 of the reflector 2 in a direction radially back toward the center axis X--X of the flash lamp 2 so as to also be effectively blocked off from view by the lamp itself.

It will be apparent, therefore, that by making possible the employment of only one moisture indicator spot 23 on the flash lamp envelope 4 of a flash lamp-reflector assembly 1 instead of the two diametrically opposite indicator spots heretofore customarily employed in such assemblies, while still being able to see the indicator spot or its reflected image irrespective of which one of its two axially oriented positions the lamp is mounted in within the reflector 2, the invention therefore has the advantage of requiring only half the amount of moisture indicator material, in the production manufacture of the assemblies 1, as that previously required and thus effects an approximate 50 percent saving in material cost. Moreover, these advantages are realized without any need for incorporating into the manufacturing procedure for producing the flash lamp-reflector assemblies 1 any special manufacturing operation for orienting the flash lamp 3 into only one predetermined axially oriented position for mounting in the reflector 2 in order to assure that the one indicator spot will always be located in a position facing outwardly of the reflector 2 so as to be exposed to view. Such a special lamp orienting operation would be time-consuming and most difficult to perform. Also, assemblies 1 embodying the invention exhibit gains of around 3 percent in zonal lumen seconds light output.