DE2542458A1 - ELECTRICALLY LIGHTABLE PHOTO FLASH - Google Patents

Description

GTE Sylvania Inc., U.S.A. λ ι- / «-w r ο

25424bo

19th September 1975

GTE-PA 58

PATENT APPLICATION

Electrically ignitable photo flash lamp

The present invention relates to an electrically ignitable photoflash lamp having a tubular glass envelope one end of which has a suction nozzle, while the other end encloses one of the supply wires Has pinch foot, between the lead wires is a tungsten filament with a layer of ignition material at their ends For example, made of a powdered zirconium mixture, in the form of so-called ignition pearls, attached to the connection points ·· and the glass bulb is filled with oxygen and high-energy fuel, such as finely chopped zirconium, hafnium and aluminum metal foil.

It is known that flash lamps produce actinic light by burning the fuel, the filling with Oxygen for a quick burn "ensures.

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In some currently manufactured photoflash lamps, the ignition means consists of a pair of lead wires, which lead through a pinch foot and roughly parallel by means of a glass ball fused around both wires Position. Such a design can be found in US Pat. No. 3,739,166.

Another embodiment according to US-PS 3.77o.362 contains no glass ball, as Figure 1 shows here. Here the lead wires lead inside on opposite sides the lamp from the pinch foot, run obliquely to each other and run for a large part of their length within of the glass bulb parallel to their ends where the filament is attached.

In both versions, the supply lines in the glass bulb extend over about 40% of its length.

As soon as ignition voltage is supplied to the outwardly protruding ends of the lead wires, the filament becomes incandescent and triggers the ignition of the ignition material and thus the start of combustion. This becomes a predetermined one Amount of light generated.

Usually the oxygen is provided at a pressure of 8 atmospheres. When the lamp flashes, the Oxygen is heated so that the pressure rises to a peak about 60% higher than the initial value lies. At the same time, molten droplets of metals and oxides hit the inner wall of the glass flask,

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resulting from actinic burn. The resulting local thermal shock leads to overstressing of the glass, so that the glass envelope can splinter, crack and crumble. It was therefore used to strengthen the glass envelope and improve its printing performance (containment capability) a protective varnish applied on the outside, which consisted, for example, of cellulose acetate.

The mentioned peak value of the internal pressure occurs early in the flash cycle, between 13 and 20 milliseconds after tripping. The internal pressure then falls as the reaction consumes oxygen. After about The internal pressure is 1 atmosphere for 160 milliseconds. The possible risk of bursting is accordingly a time-dependent one Function. The internal pressure can be higher due to contamination and manufacturing tolerances. To that to compensate, you have an excess (over the stoichiometric ratio) of fuel (5-10% oversize) provided. In this way, the oxygen was used up more completely and used as a kind of lightning extinguisher. Then about atmospheric pressure was set in the glass flask. In recent times, however, you have it with Thicker protective lacquers, foils and / or thicker glass of the piston tried and an equal or approximately stoichiometric equilibrium applied. An improved light output was thereby achieved.

In addition to using a glass bead to separate

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keep the filament leads using certain other types of lamps such as described in U.S. Patent 3,110,054, also one around part of one lead wire located glass tube serving as insulation protection, which extends from the glass bead to the glow wire, to prevent post-ignition short circuits via the lead wires. Such a peculiarity will be for the correct operation of certain flash sequencing circuits for Control of flash lamp dipole rows needed. For example, if in one currently being launched Photo flash series execution a short circuit between the molten lead wires in the first (or one of the subsequent) lamp by the sequential circuit If the row to be flashed occurs, the whole row of lamps is rendered useless.

Although an insulating glass tube reliably provides the desired lead insulation function, it increases its Use considerable both the manufacturing and material costs of the lamp unit. E.g. after a current manufacturing method for processing the Zündträgerauf building the lead wires initially in the form made of a hairpin with the closed end pointing down. The glass bead is then attached to the lead wires melted to fix their spacing; this is the conventional bead attachment process. Next, the closed end of the hairpin is cut off in the normal way. The support structure is then rotated 180 °, and a glass tube is placed over one of the lead wires so that it rests on the ball. The end of the tube in contact with the bead then becomes just that wide

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heated so that it melts onto the bead, but without to deform its upper part. The support structure must then be rotated again by 180 ° in order for it to work to make further processing ready.

It will be noted that this method is used twice Turning the support structure by 180 ° requested. She demands also a tube feeder and a tube filler, a device for adjusting one of the wires so that the glass tube can be slipped over it, as well as great dexterity of the person operating the machine.

Another disadvantage of this relatively bulky bead-tube ignition structure is that it significantly reduces the internal volume of the lamp - a factor that contributes to the currently widespread sub-miniature lamp size is of great importance, the inner volume of which is a lot is smaller than a cubic centimeter. The presence of the bead-tube assembly gives a higher initial pressure and also causes difficulties in achieving a good filling distribution within the glass envelope want.

It is noted that the US Patent No. power. 3,817,683 a stoichiometric range is known, which includes the use of excess oxygen in a lamp with bead Zündaufbau. However, there is no reference in the patent to the use of a selected excess of oxygen for the purpose of preventing

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-B-

Post-ignition short-circuits. Further, US patents 2,272,059 and 3,263,457 flash lamp designs propose without beads, but again none of these patents is discussed avoiding restriking shorts.

In addition to the disadvantages listed above, there are many
Experiments have found that the relatively bulky, bead and bead-tube lead structures in subminiature flash lamps reduce the efficiency of flash lighting because of their heat absorbing effect. So it was found that
this effect the light output power by more than.
10-15% when compared to lamps that use ignition structures that do not contain glass beads or beads and tubes.

The invention was therefore based on the problem of the shortcomings and disadvantages of the known photoflash lamps and theirs
Avoid manufacturing methods and achieve improved flash output. It should also be ensured that lead short circuits occur in the photoflash lamp after the flash cycle. At the same time, it is required that the manufacturing cost is considerable
are lower than before.

According to the invention, these tasks and requirements are described in accordance with the identifier for the type of flash lamp mentioned of the main claim, which provides a combination of measures, solved.

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Further details can be found in the remaining claims and the description of a preferred exemplary embodiment refer to.

The characteristic combination of measures provides that a certain amount of the combustion-supporting Gas, such as oxygen, is provided which is greater than that necessary for the stoichiometric reaction Amount. It is thereby achieved, as has been found, that the leads completely during the The lightning cycle oxidizes or burns, thus eliminating the risk of a short circuit. Also will by choosing the cross section of the lead wires, namely a multiple of the diameter of the individual chips of the fuel, causes the lead wires to burn towards the end of the flash cycle and only a little or there is almost no effect on the usable light output

The amount of oxygen that is present in excess of the amount which is required in relation to the combustible material for the stoichiometry is at least 20 percent, and preferably between 25 and 50 percent of the stoichiometric amount required for the entire chemical reaction with the supply line parts inside the glass envelope is required. In order to support the supply line burn-back in such a way that an open circuit can arise, the supply lines inside the glass envelope protrude from the pinch foot at the inner end of the envelope on opposite sides and incline towards-

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each other all the way to their inner ends where the filament is attached.

The improvement in light output that results from this lamp design allows one 10-1½ percent reduction in the required amount of combustible foil shreds, while still maintaining the necessary light exit pier characteristics. if approximately the same amount of oxygen based on the previous fuel element measurement is maintained, there is enough excess to oxidize or burn off the lead wires, so after the Flashing an open circuit state is created. With this new element measurement (stoichiometry) is an effective, lower internal pressure due to the larger internal volume due to the beadless structure available. The relative simplicity of the lamp allows for improved manufacture to much lower ones Costs.

A preferred exemplary embodiment is described below with reference to the drawing.

The only figure represents an electrically ignitable photo flash lamp that has a hermetically sealed light emitting glass envelope 10 made of tubular glass, which has a pinch foot 12 delimiting it at one end and a suction tip delimiting the other end. A certain amount of combustible fuel 16, such as carved zirconium or hafnium foil, is located in the glass envelope 10. The glass envelope

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is also with a filling of incineration Gas such as oxygen. The filling amount is greater than that for the stoichiometric chemical Reaction with the fuel 16 required amount. The amount selected and the purpose of this excess oxygen element measurement is a particular one Aspect of the invention and is discussed further below.

The ignition assembly of the invention includes a pair melted by the pinch foot 12 and at one end the glass envelope 10 inwardly protruding lead wires 1Θ and 20. A filament 22 is across the leads stretched near its inner end. On the inner ends of the leads 18 and 20 at the connection points with the filament there are beads 24, 26 of ignition material. It can be seen that that End of the glass envelope, namely the pinch foot 12, the only means within the glass envelope 10 for support the leads 16 and 20 are separate from each other. The leads 18 and 20 are made of metal wire with a Thermal expansion coefficient, which corresponds essentially to that of the glass envelope 10, whereby an adapted closure (match seal] is created. If, for example, the glass envelope 10 made of borosilicate hard glass with a coefficient linear thermal expansion between 0 and 300 C in the range of 40-50 "χ 10" per degree Celsius the leads 18 and 20 made of an iron, nickel and cobalt alloy, such as Kovar, the one low thermal expansion coefficient of approx. 50 χ 10 has between 25 and 300 ° C per degree Celsius. the

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Lead wires 18, 20 within the lamp protrude from the pinch foot 12 on opposite sides of the envelope close to the tube wall and slope towards each other all the way to their inner end. In order to increase the penetration depth of the ignition structure into the interior of the To keep the glass envelope 1G as minimal as possible, the inner length of the leads 18, 20 is limited to one Expansion of approx. 20-25% of the inner length of the envelope, calculated from the pinch foot 12.

According to the invention, that in the lamp is in excess of that sufficient amount of oxygen contained for the elements measurement in relation to the fuel 16, so that when When the lamp flashes, the fuel 16 is completely burned and the leads 18 and 20 in the lamp burned back enough to be an open circuit to accomplish. To determine the additional element measurement necessary for the complete combustion of the interior The theoretical calculation shows that about 0.25 oxygen atmospheres for each Milligrams of lead material per cubic centimeter of envelope content are required. In practice, however, it is found that - if at least 20%, and preferably 25-50% of the additional oxygen requirement is provided - this meets the required post-flash condition to achieve the open circuit. The complete one Taking into account the element measurement for the system can now be easily determined by taking the weight of the fuel 16 plus the weight of the lead material within the lamp envelope is calculated to be the to determine the amount of oxygen required in the lamp envelope.

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As is known in the art, the 100% element measurement relates to the ideal chemical reaction between the combustible metal and oxygen in the flashlamp where there are enough oxygen atoms to react with each metal atom, e.g. if the metal is hafnium the reaction is Hf + 0 = HfO ₂ - The standard formula for the relationship between the oxygen gram molecules and the metal gram molecules to be burned is

W = ^PV
K ~

where W is the filling weight in milligrams, P is the pressure in mercury centimeters, V is the lamp volume in cubic centimeters and K is a derived proportionality constant, which allows the metal milligrams to the oxygen pressure in Oueckilberzentimeters and to the To relate cubic centimeters of the lamp volume. Hence, K is a function of the metal used, i.e. the atomic weight of the metal, the gas constants from the ideal gas law and the gram-molecule ratio Metal / oxygen in the final oxide product. It has been established, for example, that K equals approx. 20.4 for the Kovar alloy, 20.4 for zircon and 10.4 for hafnium. Accordingly, the above equation can be applied to the filling weight (W) dissolved to determine the metal needed to completely burn the oxygen in the lamp; or the equation can be solved for P to determine the oxygen pressure needed to achieve to burn off all of the metal in the photo flash. This relationship is called "one hundred percent element measurement".

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A typical photoflash lamp can be used in accordance with the invention a tubular borosilicate shell with pinch foot and Kovar or Rodar leads as in the drawing to have. Four layers of cellulose acetate have been applied to the outer surface of the casing. In terms of size As seen, the coated shell has an outer diameter of about 0.280 inches, an inner diameter 0.200 inches and an inside length of approximately 11/16 inches. The leads 18, 20 extend inwardly within the glass envelope 10 to about 1/8 inch, counted from the end of the envelope at the pinch foot 12. The gap between the leads 18, 20 in the pinch foot 12 is 3/16 of an inch and between their inner ends - in the Glass envelope 10 approx. 1/16 inch. The diameter of each lead 18, 20 is approximately 14 mils (0.001 inch = 0.0254 mm), although typically it can vary from 10 to 16 mils for different types of photoflashes. As in As shown in the drawing, the leads 18 and 20 made of Kovar or Rodar carry a fine tungsten thread inside the lamp with beads of ignition material 24, 26 around the inner lead ends.

The glass envelope 10 has an internal volume of approximately 0.35 cubic centimeters, and the fuel filling 16 consists from approx. 25 milligrams of chopped hafnium foil, whereby the cross-section of each hafnium foil strand is approx.

1 square mil {= 0.00065 mm ² ). With different flash lamp constructions it can also be up to

Vary 2 square mils. To determine the amount of oxygen filling in atmospheric pressure, the

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the following formula derived from the above can be used:

P = ^WK

V χ 76 cm.

According to the invention, the lamp should contain sufficient oxygen to achieve the required 100% stoichiometric chemical reaction with the flammable material hafnium plus a reasonable excess of oxygen to burn back the leads sufficiently. As mentioned above, it was found that the excess oxygen, the amount above the amount required for the element measurement in relation to the fuel is at least 20% of the stoichiometric amount, which is required for the chemical reaction with the supply line parts located within the casing. However, an excess stoichiometry of well over 50% reduces the limitation capability. Hence becomes a Range between 25 and 50% preferred as excess stoichiometric requirement for burning back the supply lines. in the present specific example is an excess of 50% of the stoichiometric amount of oxygen as it is for the chemical reaction with the supply line parts required within the envelope is used, their weight with approx. 6 milligrams has been established. The K for the lead material (Kovar or Rodar) is about twice as large like the K for hafnium, so only 50% of that required for the element measurement in relation to the lead material Excess oxygen has the effect of bringing the two constants to an average. That is called the full equation for the resolution after

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the oxygen demand would read

P " ^W 1 ^K 1 _ ° ' ^{5 W} 2 ^K 2
V χ 76 cm V χ 76 cm

where W. is the weight of the hafnium in the lamp, W _{2 is} the weight of the leads in the lamp, K. is the constant for hafnium Cd.h.10.4) and K _{2 is} the constant for the Kovar lead material (i.e. 20, 4). Since 0.5 is equal to 10.2, which is roughly _{equal to K 1} , the formula can be

CW ₁ - W ₉ ) K

ρ =! ^z

V χ 76 cm

be simplified. Then when the values are inserted, it becomes:

P = C25-6) (10.4) ₁₂ atmospheres. (0.35) (76)

Accordingly, the photo flash lamp in our example is filled with approx. 12 atmospheres of oxygen to enable a powerful light output and sufficient burn-back of the supply lines so that the Post-ignition short-circuit does not occur as desired. Furthermore, since the cross section of the supply lines is several times higher is greater than the average cross-section of each of the strands of the cut hafnium foil, burn the finer chips first to provide a powerful light output while the feed lines

burn back towards the end of the flash cycle.

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While the invention has been described in terms of a specific preferred embodiment, it is it is possible that those skilled in the art can make changes thereto without departing from the scope of the invention.

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Claims (10)

Patent claims : Electrically ignitable photo flash lamp, which has a tubular glass bulb, one of which End has a suction nozzle, while the other end surrounds the lead wires Has pinch foot, between the lead wires is a tungsten filament at their inner ends with a layer of ignition material, for example made of a powdered zirconium mixture, in the form of so-called Ignition beads, attached to the connection points and the glass flask is filled with oxygen and high-energy fuel, such as finely chopped zirconium, hafnium and aluminum metal foil, characterized by the combination of the following measures: A. An airtight, light-transmitting glass envelope (10), B. A quantity located in this glass envelope (10) Fuel (16); C. A combustion-promoting gas in the glass envelope (10), in an amount that exceeds that required for a stoichiometric chemical reaction with said fuel (16) is;. . .. C. An ignition device located in the glass envelope (10), which is in operative relation to said fuel (16) and a pair of lead wires (18,20), which in one end of the glass envelope (10), the pinch foot (12) are tightly closed and protrude into it, the end of the glass envelope (10) the only means is to carry the lead wires (18, 20) separately from one another within the same - 17 - 609816/0712 E. The amount of gas that is in excess of that for the element measurement in relation to the fuel (16) required amount and at least 20% of the stoichiometric amount is that for the chemical Reaction with the lead wires (18, 2G) inside the glass envelope (10) is required, which causes the flashing the photoflash lamp burns the fuel (16) and the lead wires (18, 20) are sufficient burn back to create an open circuit. 2. Electrically ignitable photo flash lamp according to claim 1, the characterized in that / combustion promoting gas is oxygen and its amount in excess of the amount required for element measurement in relation to said fuel is required, approx. 25-50% of the stoichiometric amount required for the chemical reaction with the Lead wires (18,20) within the sheath is required. 3. Electrically ignitable photo flash lamp according to claim 1, characterized in that the ignition device further includes a filament (22) securing across the lead wires (18,20) near their inner ends is, wherein the lead wires (18,20) within the sheath from the end of the pinch foot (12) on opposite sides Step out the sides and lean towards each other all the way to the inner ends. 4. Electrically ignitable photo flash lamp according to claim 3, characterized in that the combustion promoting Gas is oxygen. - 18 - 809816/0712 -1B- 5. Electrically ignitable photo flash lamp according to claim 1, characterized in that the fuel (16) consists of many fibers of fuel (16) and the cross section of each lead wire (18, 20) is several times larger than the average cross-section of each of the fibers of the fuel (16). 6. 'Electrically ignitable photo flash lamp according to claim 5, characterized in that the combustion-promoting gas is oxygen, the average cross section of each of the fibers of the fuel material (16) about 1-2 mil ² and the wire diameter of each of the lead wires (18,20) etwa10-16 mil.beträgt. 7. Electrically ignitable photo flash lamp according to claim 1, characterized in that the glass envelope (10) has a pinch foot (12) which delimits one end, and with a suction tip (14J ₁ which delimits its other end, the lead wires (18 , 20) extend through the pinch foot (12) and are firmly closed in it, and wherein the lead wires (18, 20) consist of metal wire which has a coefficient of thermal expansion which corresponds essentially to that of the glass of the glass envelope (10). 8. Electrically ignitable photo flash lamp according to claim 7, characterized in that the lead wires (18, 20) from the pinch foot (12) inwards into the Glass envelope (10) extend over a distance of approx. 20-25% of the inner length of the glass envelope. - 19 - 609816/0712 9. Electrically ignitable photo flash lamp according to claim 8, characterized in that the lead wires (18, 20) within the glass envelope (10) from the pinch foot (12) from opposite sides of the glass envelope (10) protrude near their tube sidewalls and extend all the way to their inner ends lean towards each other? in which further the combustion-promoting gas is oxygen and the amount of oxygen that is in the Excess to that which is required for element measurement in relation to the fuel (16), approx. 25-50% of the stoichiometric amount required for the chemical reaction with the lead wires (18,20) is required within the glass envelope (10). 10. Electrically ignitable photo flash lamp according to claim 9, characterized in that the inner diameter of the Glass envelope (10) approx. 0.2 inches, the distance between the lead wires (18, 20) in the pinch foot (12) about 3/16 inch and the distance between the inner ends of the lead wires (18,20) inside the glass envelope (10) be approximately 1/16 of an inch. 609816/0712 ι ^l0 Le e rs e ί te