US3895902A - Photoflash lamp - Google Patents

Photoflash lamp Download PDF

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Publication number
US3895902A
US3895902A US179056A US17905671A US3895902A US 3895902 A US3895902 A US 3895902A US 179056 A US179056 A US 179056A US 17905671 A US17905671 A US 17905671A US 3895902 A US3895902 A US 3895902A
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US
United States
Prior art keywords
envelope
lamp
strands
combustible
filamentary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US179056A
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English (en)
Inventor
David R Broadt
Donald E Armstrong
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GTE Sylvania Inc
Original Assignee
GTE Sylvania Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE788531D priority Critical patent/BE788531A/xx
Application filed by GTE Sylvania Inc filed Critical GTE Sylvania Inc
Priority to US179056A priority patent/US3895902A/en
Priority to GB4046372A priority patent/GB1401314A/en
Priority to JP8674772A priority patent/JPS5441204B2/ja
Priority to ZA726043A priority patent/ZA726043B/xx
Priority to CA150,900A priority patent/CA975572A/en
Priority to DE2244182A priority patent/DE2244182A1/de
Priority to AU46490/72A priority patent/AU4649072A/en
Application granted granted Critical
Publication of US3895902A publication Critical patent/US3895902A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B15/00—Special procedures for taking photographs; Apparatus therefor
    • G03B15/02—Illuminating scene
    • G03B15/03—Combinations of cameras with lighting apparatus; Flash units
    • G03B15/04—Combinations of cameras with non-electronic flash apparatus; Non-electronic flash units
    • G03B15/0478—Combinations of photographic apparatus with percussion type flash ignition systems
    • G03B15/0484—Constructional details of the flash apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K5/00—Light sources using charges of combustible material, e.g. illuminating flash devices
    • F21K5/02—Light sources using charges of combustible material, e.g. illuminating flash devices ignited in a non-disrupting container, e.g. photo-flash bulb
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K5/00—Light sources using charges of combustible material, e.g. illuminating flash devices
    • F21K5/02—Light sources using charges of combustible material, e.g. illuminating flash devices ignited in a non-disrupting container, e.g. photo-flash bulb
    • F21K5/023—Ignition devices in photo flash bulbs

Definitions

  • This invention relates to photoflash lamps and particularly to subminiature and smaller photoflash lamps containing a filamentary combustible of the shredded foil type.
  • Subminiature photoflash lamp i.e. lamps having an envelope volume of less than one cubic centimeter, are presently mass produced in large quantities for use in the small photographic flashlamp units referred to as flashcubes.
  • flashlamp units of this type comprise: a container hav ing a plurality of closed transparent sides; a plurality or reflectors disposed in the container, one along each side thereof; and a photoflash lamp disposed in operative relationship with respect to each of the reflectors.
  • Each of the subminiature flashlamps employed in the unit consist of a hermetically sealed, light transmitting glass envelope which contains a filamentary combustible material, such as shredded zirconium foil, and a combustion-supporting gas, such as oxygen.
  • the envelope also includes an electrical ignition system comprising a tungsten filament supported on a pair of lead-in wires having a quantity of ignition paste on the inner ends thereof adjacent to the filament. This type of lamp is operated by the passage of electric current through the lead-in wires.
  • a mechanical primer is sealed in one end of the lamp envelope.
  • the primer may comprise a metal tube extending from the lamp envelope and a charge of fulminating material on a wire supported in the tube. Operation of the percussive photoflash lamp is initiated by an impact onto the tube to cause deflagration of the fulminating material up through the tube to ignite the combustible disposed in the lamp envelope.
  • the percussive-type lamps are employed in multi-lamp cubical units having respective pre-energized striker springs for each lamp as described in U.S. Pat. No. 3,597,604.
  • the combustible mate rial commonly employed in presently available photoflash lamps consists of a loosely distributed quantity of filamentary material of a type commercially known as shredded foil.
  • the material is made by cutting or shredding a thin sheet of ribbon of suitable metal foil into thin strands.
  • Aluminum and magnesium foil have been used for this purpose, although more recently, the use of zirconium has been found to provide significant photometric advantages, as described in U.S. Pat. No. 3,067,601.
  • the use of such long strands in small size lamps increased the difficulty of obtaining good distribution of the shredded foil by the pneumatic foilloading methods which are conventionally used.
  • the use of these shorter strands of shredded foil has the advantage, of affording a great many more loose ends serving as ignition points for a given weight or charge of shredded foil in the lamp, thereby facilitating the ignitionof the shredded foil in a manner which tends to produce increased useful light output therefrom. It is observed that if the strands of shredded foil are too short, they will not maintain themselves in place in the lamp envelope in distributed position, but instead will drop down or collapse into the bottom region of the lamp.
  • the Anderson patent teaches that it is necessary to maintain the individual foil strands above a minimum length of the order of 1 inch or a length such that the ratio of the individual strand length in inches to the maximum envelope diameter in inches is at least approximately 1.3.
  • the Anderson patent instructs that the filamentary material should be distributed loosely within the bulb and as uniformly as possible throughout the space occupied thereby in order to insure the most favorable combustion conditions for the material.
  • one of the principal objects of this invention is to provide a photoflash lamp which provides an improved efficiency of combustion, thus improved light output, using the more common combustible materials, such as zirconium, without having to resort to expensive and exotic metals such as, hafnium, scandium, indium, alloys, or laminates.
  • a particular object of the invention is to improve the photometric output of subminiature and smaller photoflash lamps by improving the efficiency of the burning shredded combustible.
  • Another object is to provide a high light output photoflash lamp which may be more economically produced than like-sized lamps heretofore available for providing similar light output characteristics.
  • the strands of shredded combustible may be shortened to a length even less than the internal diameter of the lamp to provide an increased efficiency of combustion without loss of supportability by recognizing that optimum shred length can be determined by a relationship involving the inside diameter of the lamp, the effective internal bulb length, the quantity, or weight, of the combustible, and the composition and cross-section of the strands.
  • the photoflash lamp in accordance with the invention employs a filamentary combustible having a strand length inversely related to the weight of the filamentary material, with the filamentary material being made selfsupporting within the lamp envelope by appropriately increasing the density of the strands.
  • FIG. 1 is an elevational view of an electrically ignitable photoflash lamp containing a filamentary combustible in accordance with the invention
  • FIG. 2 is a sectional elevation of a precussive-type photoflash lamp containing a filamentary combustible in accordance with'the invention.
  • FIG. 3 is a plot of light output in terms of zonal megalumens against time in milliseconds for 4 inch shreds and short shreds in similar envelopes.
  • FIGS. 1 and 2 respectively illustrate electrically ignited and percussive-type photoflash lamps embodying the principles of the invention.
  • the electrically ignitable lamp comprises an hermetically sealed lamp envelope 2 of glass tubing having a press 4 defining one end thereof and an exhaust tip 6 defining the other end thereof.
  • an ignition means comprising a pair of lead-in wires 8 and 10 extending through and sealed into the press.
  • a filament l2 spans the inner ends of the lead-in wires, and beads of primer 14 and 16 are located on the inner ends of the lead-in wires 8 and 10 respectively at their junction with the filament;
  • the lamp envelope 2 has an ID. of less than one-half inch, and an internal volume of less than 1 cc.
  • a combustion-supporting gas, such as oxygen, and a filamentary combustible material 18, such as shredded zirconium foil, are disposed within the lamp envelope as will be described in more detail hereinafter.
  • the primer 28 comprises a metal tube 30, a wire anvil 32 and charge of fulminating material 34.
  • a combustible such as filamentary zirconium 36 and a combustionsupporting gas such as oxygen are disposed within the lamp envelope, as will be detailed hereinafter.
  • the wire anvil 32 is centered within the tube 30 and is held in place by a circumferential indenture 38 of the tube 30 which laps over the head 40 or other suitable protuberance at the lower extremity of the wire anvil.
  • Additional means such as lobes 42 on wire anvil 32 for example, may also be used in stabilizing the wire anvil, supporting it substantially coaxial within the primer tube 30 and insuring clearance between the fulminating material 34 and the inside wall of the tube 30.
  • a refractory bead 44 is fused to the wire anvil 32 just above the inner mouth of the primer tube 30 to eliminate burnthrough and function as a deflector to deflect and control the ejection of hot particles of fulminating material from the primer.
  • the lamp of FIG. 2 is also typically a subminiature type having envelope dimensions similar to those described with respect to FIG. 1.
  • the lamp of FIG. 1 is electrically ignited, usually from a battery source, and the lamp of FIG. 2 is percussion-ignitable, the lamps are similar in that in each the ignition means is attached to one end of the lamp envelope and disposed in operative relationship with respect to the filamentary combustible material. More specifically, the igniter filament 12 of the flash lamp in FIG. 1 is incandesced electrically by current passing through the metal filament support leads 8- and 10, whereupon the incandesced filament ignites the beads of primer 14 and 16 which in turn ignite the combustible 18 disposed within the lamp envelope. Operation of the percussive-type lamp of FIG. 2 is initiated by an impact onto tube 30 to cause deflagration of the fulminating material 34 up through the tube to ignite the combustible 36 disposed within the lamp envelope.
  • the filamentary combustible employed in flash lamp envelopes normally comprises a shredded metallic foil, such as zirconium.
  • the metallic foil manufactured for this application is normally provided in thicknesses of about or somewhat less than 1 mil and in widths of about 2 to 4 inches.
  • the foil is then processed through standard shredding equipment to produce desirable cross sections of about 1.2 to 2.0 square mils, depending upon the characteristics of the various photoflash lamps. Accordingly, the strands of shredded foil are normally about 2 to 4 inches long and in some instances, as described by the aforementioned Anderson et al patent, the foil may be split in half to provide 1 inch strand lengths for the filamentary combustible.
  • this relatively short strand combustible has been found useful for improving the light output in smaller sized flashlamps, with the prior art teaching that a minimum length of 1 inch or 1.3 times the bulb diameter was necessary to render the combustible self-supporting. Even when using these relatively short shreds of metallic foil, however, there still results an undesirably low efficiency of combustion in subminiature flashlamps. It will be noted that these strand lengths, although relatively short, are nevertheless more than two times greater than the ID. of a submarine lamp envelope, which is typically much less than one-half inch.
  • the subminiature lamp envelope can be successfully rendered self-supporting by appropriate selection of the strand density, or more specifically the weight of the combustible.
  • the use of such short strands causes the distribution of the combustible to be minimal at the envelope walls and more dense toward the center of the lamp, a feature which appears to particularly counteract the efficiency reducing effects attributable to the wall hugging characteristics of conventional longer shreds.
  • an optimum strand length, with respect to maximizing the efficiency of combustion is dependent upon a relationship involving the inside diameter of the lamp envelope, the effective internal bulb length, the weight of the combustible, and the composition and cross-section of the strands.
  • the strand length, in inches, of the filamentary combustible mate rial for photoflash lamps is determined by the following formula:
  • K Strand Length K
  • [D is the inside diameter of the lamp envelope in inches
  • W is the weight of the filamentary material within the lamp envelope in milligrams
  • L is the average effective internal length of the lamp envelope in inches
  • K is a constant dependent upon the composition and cross-section of the strands of filamentary material.
  • the constant K is determined empirically, for example, a constant K 22.3 has been found suitable for shredded zirconium with a 1.1 to 1.2 square mil crosssection; and a constant K 36.6 appears to be suitable for shredded hafnium with a 1.1 to 1.2 mill crosssection.
  • the above formula tends to optimize the length of the combustible strands for the various lamp envelope sizes and till arrangements that may be desired.
  • K takes into consideration the fact that the composition of the combustible shreds may vary for different lamp designs dependent upon the cost considerations and the light output requirements of the applications for which that lamp is directed. As the crosssection of the shredded strands is significant factor in the determination of flash timing, K also takes this design factor into consideration.
  • the strand cross-section also determines individual strand rigidity or supportability as well as the number of strands; hence it is desirable to optimize to the smallest usable cross-sections so as to obtain the greatest I number of individual strands.
  • the formula also accounts for the variation in internal diameter of various lamp types.
  • the relationship indicates that strand length decreases faster than a reduction in the envelope internal diameter.
  • the strand length can be significantly shorter than the ID. of the lamp envelope.
  • strand length and fill weight are the remaining variables. If the strand length is shortened, the number of strands loaded into the lamp envelope must be increased to provide the necessary selfsupporting characteristics. To achieve a maximum efficiency of combustion, it is desirable to make the strand length as short as possible; hence, the primary limitation on strand length is the practical maximum that must be placed on fill weight. There is a certain point beyond which an increase in fill weight will pose containment problems in economically feasible envelope designs, and another point beyond which further increases in the density of the combustible fill will actually reduce the efficiency of combustion and thus the light output.
  • a further enhancement of photomeric output is obtained if the body of combustible material is concentrated in the upper two-thirds of the lamp envelope; i.e. the filamentary material occupies approximately twothirds of the envelope toward the end thereof opposite to that to which the ignition means is attached.
  • This arrangement of the fill wherein it occupies the upper twothirds of the envelope and has a density gradient increasing toward the center of the envelope is illustrated by the distribution of the filamentary combustible materials l8 and 36 in FIGS. 1 and 2 respectively. Restriction of the combustible to the upper two-thirds of the envelope is provided by subjecting the glass envelope to a mechanical shock subsequent to the foil-filling process.
  • the following table illustrates the strand lengths and fill weight concentration of zirconium shredded foil determined in accordance with the invention for four different lamp sizes along with the substantial increase in light output obtained in each case.
  • the strand length figures vary slightly from that obtained by use of the aforementioned formula as attempts were made to equally divide the available foil stock widths to avoid the creation of unusable scrap.
  • the lamp was of the electrically ignitable type, and the ordinate axis in FIG. 3
  • curve B shows the light output characteristic for a similar envelope filled with conventional 4 inch shreds of zirconium.
  • a further advantage of the relationship for determining strand length in accordance with the invention is the greater concentration of fill weight which results, thereby further contributing to increased light output.
  • the fill concentration will never be less than approximately milligrams per cubic centimeter.
  • the respective concentrations of the zirconium fill from left to right are 105 mg./cc., 77 mg./cc., 29.5 mg./cc., and 38.5 mg./cc.
  • the short shreds of the present invention also provide a significantly higher color temperature thereby enabling a reduction in density of the blue coating required for the photoflash lamp to provide a further improvement in photometric output.
  • the integrated correlated color temperature (0 msec) for the 0.270 O.D. lamp in the above table is experimentally determined to be approximately 4,872K, plus or minus 75K, as compared to a color temperature of 4,725K, plus or minus 25K, for a similar size lamp filled with 4 inch strands of zirconium.
  • Test data obtained from thousands of flashed lamps has also indicated a further unexpected advantage of using short shred lengths in accordance with the invention, namely, the combustion appears to be less violent thereby providing a much safer lamp having a substantially lower probability of explosive failure.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Luminescent Compositions (AREA)
US179056A 1971-09-09 1971-09-09 Photoflash lamp Expired - Lifetime US3895902A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
BE788531D BE788531A (fr) 1971-09-09 Lampe photo-eclair
US179056A US3895902A (en) 1971-09-09 1971-09-09 Photoflash lamp
JP8674772A JPS5441204B2 (ja) 1971-09-09 1972-08-31
GB4046372A GB1401314A (en) 1971-09-09 1972-08-31 Photoflash lamps
ZA726043A ZA726043B (en) 1971-09-09 1972-09-05 Photoflash lamp
CA150,900A CA975572A (en) 1971-09-09 1972-09-05 Photoflash lamp
DE2244182A DE2244182A1 (de) 1971-09-09 1972-09-08 Fotoblitzlampe
AU46490/72A AU4649072A (en) 1971-09-09 1972-09-08 Photoflash lamps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US179056A US3895902A (en) 1971-09-09 1971-09-09 Photoflash lamp

Publications (1)

Publication Number Publication Date
US3895902A true US3895902A (en) 1975-07-22

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Application Number Title Priority Date Filing Date
US179056A Expired - Lifetime US3895902A (en) 1971-09-09 1971-09-09 Photoflash lamp

Country Status (8)

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US (1) US3895902A (ja)
JP (1) JPS5441204B2 (ja)
AU (1) AU4649072A (ja)
BE (1) BE788531A (ja)
CA (1) CA975572A (ja)
DE (1) DE2244182A1 (ja)
GB (1) GB1401314A (ja)
ZA (1) ZA726043B (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217089A (en) * 1975-02-03 1980-08-12 Gte Products Corporation Photoflash lamp

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2857752A (en) * 1954-04-07 1958-10-28 Gen Electric Flash lamp
US2982119A (en) * 1959-04-27 1961-05-02 Gen Electric Flash lamp

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1189852B (de) * 1962-02-09 1965-03-25 Patra Patent Treuhand Elektrische Blitzlichtlampen und Verfahren zu ihrer Herstellung

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2857752A (en) * 1954-04-07 1958-10-28 Gen Electric Flash lamp
US2982119A (en) * 1959-04-27 1961-05-02 Gen Electric Flash lamp

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217089A (en) * 1975-02-03 1980-08-12 Gte Products Corporation Photoflash lamp

Also Published As

Publication number Publication date
BE788531A (fr) 1973-03-08
GB1401314A (en) 1975-07-16
AU4649072A (en) 1974-03-14
ZA726043B (en) 1973-07-25
DE2244182A1 (de) 1973-03-15
JPS4857625A (ja) 1973-08-13
CA975572A (en) 1975-10-07
JPS5441204B2 (ja) 1979-12-07

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