US2013371A - Flash light lamp - Google Patents

Description

Sept. 3, 1935. J. A. M. VAN LIEMPT ET AL- 2,013,371

FLASH LIGHT LAMP Fil ed Feb. 24, 1932 2 Sheets-Sheet 1 Sept. 3, 1935. J. A. M. VAN LIEMPT ET AL FLASH LIGHT LAMP Filed F at. 24, 1952 2 Sheets-Sheet 2 Irwenfora: JJZMuan/Lzm vfi waffle dam,

C in Patented- Sept. 3, 1935 "PATENT, OFFICE rush LIGHT. LAMP Johannes Antonius Maria van .Hempt and Pieter Leydens, Eindhoven,

Netherlands, assignors to N V. Philips Gloeila'mpenfabrieken, Eindhoven,

Netherlands Application February 24,1932, Serial No. 594,910 In the Netherlands May 5, 1931 13 Claims. The presentinvention relates to flashlight lamps.

To take photographic pictures in the dark or .in insufliciently lighted interiors in the past,

flashlight powders have been used consisting of powder mixtures which were ignited and burned in an explosive manner in the air. Such flashlight powders have various drawbacks, for instance they lose, their eifectiveness when standing in the air, they entail risk of fire, cause smoke and unpleasant odors, and have a relatively long flash-time.

As an improvement flashlight lamps have been suggested in.which the flashlight powder is provided in a sealed container and ignited by special meansand more recently flashlight lamps have been introduced which eliminate most of the above drawbacks and which consist of a gastight transparent bulb which contains a metal, for instance, aluminum or magnesium, and a gas, for instance oxygen, and in which electric ignition means are provided, for instance in the form of a filament glower. Upon ignition a rapid combustion of the metal takes place. The velocity of combustion may be increased by giving the metal a large surface area, for instance by powdering or flnely laminating same.

While such flashlight lamps have marked advantages bver flashlight powders, they are expensive to manufacture and thus their cost is relatively high, which is a very serious drawback for such lamps, which can be used only for a single exposure. Besides that there is a considerable variation in the time of exposure and of the amount of light emitted by the individual lamps due to the fact that it is extremely diflicult to provide in all of the lamps the same amounts of flashlight substance with such accuracy as to prevent the above variation; and also there is objectionable diminishing of light intensity due to the deposition of the combustion products which reduces the light output of the lamp.

The present-invention relates to novel type flashlight lamps of much lower cost, and which produce a high actinic eflect without variations between the individual lamps and without objectionable diminishing of light intensity caused by the separation of reaction products.

The flashlight lamps according to our invention, resemble the just discussed flashlight lamps in so far as they also comprise a sealed container, for instance a glass bulb, and electric ignition means, but instead of obtaining the actinic effect through the combustion of a metal or of a powder mixture, such effect is obtained by a -gas reaction which takes place between the gases of a gas mixture or through the decomposition of a single gas providedin the bulb.

To provide a flashlight lamp having a sealed container, in which the actinic effect is essentially or solely obtained by such rious difliculties have to be which are the following:

The amount of gas or gases to be provided in a normal size lamp bulb have to have suflicient actinic effect to satisfy the photographic requirement imposed on such lamps.

Also no gradual reaction between the gases of the mixture or the decomposition of the single gas should take place while the lamp is stored and the reaction should not be initiated in any way except by the proper action of the electric ignition means provided in the lamp.

Nor should the pressure developed during the reaction exceed the limits which a standard strength lamp bulb can safely stand.

Also provision should be made to avoidexplosion in the case of leaky lamps.

In the same way obstacles in the manufacture of such lamps have to be overcome. For ingas reaction, vasurmounted among stance, special means are to be provided to pre-" vent an explosion when the glass bulb containing the explosive gas or gas mixture is air-tightly sealed, as this involves the heating of part of the glass bulb to its melting. point-as a rule by means of an. open gas flameand this might easily cause ignition of the gas filling.

As stated, the present invention overcomes all of the difliculties aforesaid and provides for a flashlight lamp which gives a high actinic effect and is much cheaper and simpler to manufacture than the flashlight lamps previously made. The actinic efiectis also raised by the fact that a gas reaction is provided which does not evolve reaction products which diminish the light intensity. Referring to, the drawings which form part of this specification:

Figure 1 is a schematic side view of a flashlight lamp embodying our invention.

- Figs. 2' and 3 are fractional side views of a flashlight lamp embodying our invention, showing means to prevent explosion of the gas filling during the sealing off of the bulb by means of an opening provided in the exhaust tube and a rubber sleeve surrounding same.

Figs. 4 and 5 are fractional side views showing the exhaust tube of the lamp and means associated therewith which permit the sealing of the exhaust tube without the use of a flame.

Fig. 6 is a fractional side view of a flashlight lamp according to our invention, in which a material is provided in the exhaust tube which prevents an explosion to pass from the exhaust tube to the filling of the lamp.

Fig 'l is a front view of the lamp shown in Figs. 2 and 3 with parts broken away.

Fig. 8 shows a flashlight lamp according to the invention, in which the outside of the bulb is provided with a transparent varnish layer.

Fig. 9 shows a flashlight lamp in which both the outside and the inside of the bulb is provided with a transparent varnish layer.

Fig. 10 shows a flashlight lampin which a fuse is inserted in one of the leads of the glower.

Fig. 11 shows a flashlight lamp in which the glower is provided with salts producing a colored light.

Fig. 12 shows a flashlight lamp in which an ignition mixture is applied to the glower.

Referring now to Fig. 1, there is shown a lamp comprising an envelope I which is preferably a lamp bulb similar'to those used in connection with regular incandescent lamps. 2 is a stem, 4-! are suitable lead-in wires supporting a filamentary glower 2i which serves as electrical ignition means. A gas filling 22 is provided in the bulb.

The lamp may be provided with any suitable base,

for instance, a standard screw base to which the lead-in wires 4-4 are connected in known manner. The gas lamp is ignited by applying a suitable Voltage across the glower 2|, whereupon the gas reaction giving the actinic effect takes place. If desired an ignition mixture may be used. .However, neither the electric glower nor the ignition mixture contribute to any great extent to the actinic effect of the lamp, which is .entirely or substantially entirely obtained by the gas reaction taking place between the mixture of gases or by the decomposition of a gas.

As examples of gas mixtures the reaction of which is attended with an actinic effect, may be mentioned carbon monoxide andoxygen, carbon disulphide and oxygen, carbon oxysulphide and oxygen, laughing gas and hydrogen, ammonia and oxygen, formaldehyde and oxygen, cyanogen and oxygen, hydrogen sulphide and oxygen, etc. Of these examples the first mentioned three show a very strong actinic effect, and lend themselves especially well for carrying the invention into efinherently give the highest light quantity, and

also using as high pressure as admissible, as large volume as possible, and by avoiding the presence of indifferent materials.

However, due topracticalconsideration, limits are set on both the pressure and the size of the lamps to be used. High gas pressures would require exceedingly strong and expensive construction of the lamp bulb so as to avoid the danger of the lamp bulb bursting as a result of the reaction, and even with the strongest construction the possibility of breakage of the lamp is still present, and the bursting of the lamp in case of high gas pressures would be dangerous for the bystanders.

It is also evident that the size of the lamps has to be kept within reasonable limits so as not to increase the cost and also to make them suitable to be used in standard fixtures.

The lamps made according to our invention For instance, we have found that when using.

a carbon monoxide and oxygen mixture, the pressure should not exceed atmosphere.

As a further precaution, according to another embodiment of the invention,-the total pressure of the gas mixture is so selected that it is smaller than one atmosphere, and even should the lamp through leakage be filled with air to 1 atmosphere, the gas filling-air mixture does not cause such an explosion which might cause the bursting of the bulb. This is of considerable importance as in the manufacture it is difficult to avoid havmospheric air and the lower than atmospheric pressure of the gas filling.

Unless the gas filling is properly selected the air so leaking into a leaky lamp may cause the formation of a gas mixture in the lamp, which is explosive'in itself. For instance, if a bulb is filled with carbon monoxide and oxygen in the proportion of 2 volumes CO to 1 volume 02 having a total pressure of atmosphere, the bulb contains a quantity of carbonmonoxide having a partial pressure of A; atmosphere and a quantity of oxygen having a partial pressure of atmosphere. When a lamp provided with such a gas filling is leaky, air having a total pressure of atmosphere may enter whereby a. mixture is formed which contains of atmosphere of carbon monoxide, atmosphere of oxygen'and atmosphere of air, ate this mixture is explosive.

Itis known that in a mixture of carbon monoxide and oxygen the so-called under-explosion limit of carbon monoxide lies approximately at 16% of'carbon monoxide; i. e. if the mixture contains less than 16% of carbon monoxide it is nonexplosive. Thus taking account again of the possibility. that the lamp in case of a leak may fill up with air to 1 atmosphere, we have found that it is preferable not to introduce into the lamp more than 16/ atmosphere or 16/100x'76 cm: 12 cm. mercury pressure of carbon monoxide.

A filling which satisfies the above requirements and which gives satisfactory results is a mixture containing 10 cm. mercury pressure of carbon monoxide and 5 cm. mercury pressure of oxygen; viz.- a gas mixture that has a total pressure of about of an atmosphere. With such a gas filling the explosion pressure during the reaction does not exceed the safety limits, nor does an explosive mixture ,form in the-case of a leaky lamp.

According to one particular embodiment of the invention, explosion in the case of a leaky lamp may be avoided by adding to the gas mixture a material which raises the limits of the explosion.

Such materials are, for instance, argon, nitrogen, helium, carbon dioxide, and also chlorides, for

Carbon tetrachloride (CCh) lends itself exceedingly well for this purpose; for instance, the following gas mixtures: 15 volumes of carbon monoxide, 7 $5 volumes of oxygen and 1 volume of carbon tetrachloride, or 4 which layer counteracts the splintering due to'an explosion if such should take place. Such arrangement is shown in Figs. 8 and 9. In Fig. 8 the bulb l is provided on its outside surface with a transparent varnish or lacquer layer 30, whereas in Fig. 9 such layers 30-30 are applied both on the inside and outside of the bulb.

Also by providing a fuse in the lamp the risk of bursting of the bulb is greatly reduced. Such a fuse is shown in Fig. 10, where one of the lead wires consists partly of a fuse wire 23.

For instance, if a flashlight lamp having a glower designed to operate on a low voltage (for example at 4 volts) is used without a fuse and with the standard supply voltage of about 115 volts, the low resistance of the glower would represent a short circuit. This short circuit would blow out the usual high capacity (10430 amp.) fuse in the lighting circuit. Preceding this blowout of the fuse, an arc may have formed between the leads or supports of the glower, which are may develop suflicient heat to cause bursting of the bulb.

With the use-of a relatively low capacity fuse in the lamp itself both the danger of the house fuse being destroyed and the establishing of an are are avoided. The normal explosive reaction of the gas (whether there be a fuse or not) i does not cause bursting of the bulb.

A further method of avoiding a dangerous explosion in case of leaky lamps is by so selecting the gas filling and the glower than when air is present in the mixture the glower does not attain the temperature required to bring such mixture to an explosion. For instance, should the glower normally assume the explosion temperature of the reaction mixture when 4 volts are applied thereto, when air is present 4 volts will not bring the glower to such temperature as to ignite the gas filling air-mixture. The glower consists of a metal wire or ribbon, the material and dimensions of which are selected to obtain, upon application of voltage thereto, a glower temperature which is in proper relation to the explosion temperature of the gas mixture.

However, such provision is not foolproof as it might be possible to accidentally apply to the lamp. a higher than the designed voltage, for instance, in the stated case a. voltage higher than 4 volts,

in which case the glower might assume a sufli-.

- rial of the glower that its melting point is lower than the explosion temperature of the gas mixture obtained in a leaky lamp being-filled up with air up to 1 atmosphere. For instance, 'when using T a gas filling having an explosion temperature of approximately 600 C. which gas filling when filled up with air to 1 atmosphere forms a mixture the explosion temperatureof which is about 750 C., a glower may be used which consists of alu- .aoiasvl instance sioii, 'soacn, Coil.-

minum having a melting point of about 660 C. Assuming now that the flashlight lamp is designed to operate at 4 volts, at which voltage the glower assumes a temperature of about 630, this tem- 'perature will be sufllcien-tly high to cause explosion of the proper gas filling. However, should air have leaked into the lamp the temperature of the glower at 4 volts remains much below 750 C.,

and no explosion can take place.

Even in the case of such a leaky lamp, should now by some error a voltage higher than 4 volts be applied to the lamp, for instance, 8 volts or even more, the glower temperature increases but cannot exceed 660C. at which temperature the aluminum melts. Thus the explosion temperature of the gas filling and air mixture can be reached under no circumstances and the lamp is thus rendered safe in every respect.

The actinic effect of a flashlight lamp may be improved in various ways, for instance by the addition of mercury vapor which may be present in the gas filling, or be developed during the ignition. For this purpose mercury, mercury amalgam, or mercury salts, for instance, mercurous iodide, may be provided on the glower. Also the quality of the light may be influenced by providing on the glower, salts which produce a colored light, for instance by providing sodium salts which produce a predominantly yellow light, or strontium chloride'which produces a predominantly red light. In Fig. 11 the glower 2| isprovided with a substance 25, for instance a salt which produces a colored light. It is also possible to add neon to the gas filling or to use a colored bulb.

The efficiency of the lamp may also be increased by making the bulb of a type of glass which is highly transparent to ultra-violet rays. Although the flashlight lamp,.according to our invention, may be operated without'an ignition mixture, if desired such mixtures may be used to reduce the reaction time. Such ignition mixtures may be applied to the glower, so that the gas reaction sets in simultaneously at several points, and is thereby accelerated. This is shown in Fig. 12, where a suitable ignition mixture 3| is applied to the glower 2|.

As stated previously, when manufacturing lamps according to our invention, measures have to be taken to prevent explosion of the gas filling during the manufacture. Such danger is especially great when a gas filling is used which reacts at comparatively low temperatures, as in such' case there is great risk of igniting the gas filling when the exhaust tube of the lamp is Figures 2 to 7. One method of preventing the gas filling of the lamp from igniting during the sealing-oif operation is illustrated in Figs. 2, 3 and 7. The lamp is provided with an exhaust tube I which communicates with a hole 5' provided in the press 3 and thus connects the inside of the bulb with the exhaust tube 8, such practice being well-known in the socalled tipless sealing-off of incandescent lamps.

According to our novel method an aperture 6 is provided on the exhaust tube 5 of the lamp and the exhaust tube is surrounded by an elastic envelope, for instance, by a rubber sleeve I, also covering the aperture 6. While the lamp is being evacuated the ru'bber sleeve is placed in the position shown in Fig. 2. The pressure outside of the tube 8 being greater than inside of the tube, the rubber sleeve now closes the aperture 6. The exhaust tube is then sealed off at a point indicated by 8, whereupon the'rubber sleeve is displaced along the exhaust tube, as shown in Fig. 3. The

upper end 9 of the sleeve 1 is then connected to a conduit l through which the gas filling is admitted to the exhausted bulb. Thereby the gas filling passes through the tube l0 between tube 8 and sleeve 1, forcing the latter to uncover the opening 6 and permitting the gas to pass through opening 6 into the tube 8 and thus through opening into the inside of the lamp. After the filling operation the exhaust tube, together with the rubber sleeve 1 is immersed in a plastic sealing mass, for instance, picein or sealing wax, which subsequently is'cooled down. It is not altogether necessary to provide such a. sealing mass, and the' by a rubber tubing l3. After the bulb has been exhausted and filled with the proper gas mixture, the tubes II and I2 are somewhat separated, for instance, by pulling the tube ll downwardly, and a, portion of the slightly stretched rubber tube is air-tightly pinched by a member I. The rubber tube is then cut ofi above its pinched portion, and sealed by means of a sealing compound, as picene or sealing wax, which hardens in situ.

A still further method to prevent the gas reaction from taking place during the sealing-oft of the exhaust tube, is by providing in the exhaust tube a porous material which prevents the propagation of an explosion from the exhaust tube towards the bulb, if, such should occur in the former. Such porous material may be, for instance, glass wool or metal gauze.

This arrangement is illustrated in Fig. 6, in which a porous material IQ, for instance, a metal gauze, is arranged within the exhaust tube 8 on its end adjacent to the bulb. Should during the sealing-ofi operation an explosion occur in the exhaust tube, the metal gauze will act quite similarly to the gauze screen provided around a miner's lamp, whereby explosion of the gas filling of the bulb is avoided. If desired, a rubber sleeve and a vent-hole in the exhaust tube, as shown in Figs. 2 and 3, may be also used in conjunction with the construction shown in Fig. 6, the latter acting as a safety valve, as has been explained previously. What we claim as new and desire to secure by Letters Patent is:

In the claims.

1. A flashlight lamp comprising a closed container of actinic light-transmitting material, a gas filling therein, electric ignition means to establish a gas reaction in said gas filling, substantially the wholeactinic effect of the lamp being due to the gas reaction, the gas pressure during said reaction being too low to cause rupturing of the container.

2. A flashlight lamp comprising a closed container of actinic light-transmitting material, a gas filling consisting of carbon disulphide and oxygen. and electric ignition means to establish a reaction between said carbon disulphide and oxygen, the gas pressure during said reaction being too low to cause rupturing or the container.

3. A flashlight lamp comprising a closed con- -tai ner of actinic. light-transmitting material, a

gas filling consisting of nitrogen chloride, electric ignition means to cause decomposition of said gas, substantially the whole actinic effect of the lamp being due to the decomposition of said gas, the gas pressure during said decomposition being too low to cause rupturing of the container. 7

4. A-flashlight' lamp comprising a closed container of actinic light-transmitting glass, a gas filling and electric ignition means to establish a gas reaction inisaid gas filling, said gas filling having a sufficiently low initial pressure to forestall the occurrence of an explosion pressure which would cause bursting of the bulb.

5. A flashlight lamp comprising a closed con tainer of actinic light-transmitting glass, a gas filling, electric ignition means to establish a gas reaction in said gas filling, the pressure of said gas filling being oi?v such low value that when air tablish a gas reaction in said gas filling, and carbon tetrachloride in said gas filling to increase the explosion limit of said filling, the gas pressure during said reactionbeing too low to cause rupturing of the container. v

8. A flashlight lamp comprising a closed container of actiniclight-transmitting material, a gas filling therein having a pressure less than one atmosphere, and an electric glower to establish a gas reaction in said gas filling, the operating temperature of said glower being, above the explosion temperature of said gas filling, but below the explosion temperature of a gas mixture which consists of the said gas filling, and of an amount of air which brings the pressure of said mixture to one atmosphere.

9. A flashlight lamp comprising a closed con.- tainer of actinic light-transmitting material, a gas filling therein, having a pressure less than one atmosphere, and an electric glower consisting of a material the melting point of which is lower than the explosion temperature of a gas mixture consisting of said gas filling and-of an amount of air which brings the pressure of said mixture to one atmosphere.

10. A flashlight lamp comprising a closed container consisting of ultra-violet light transmitting vitreous material, a gas filling in said container and electric ignition means to establish gas reac-' tion in said gas filling, substantially the whole actinic effect of the lamp beingdue to said gas reaction, the gas pressure during said reaction being too low to cause rupturing of the container.

11. A flashlight lamp comprising a closed container of actinic light-transmitting material, a gas filling and electric ignition means to establish a gas reaction in said gas filling, said electric ignition means comprising a glower and an ignition mixture applied to said glower, the gas pressure during said reaction being too low to cause rupturing of the container.

12. A flashlight lamp comprisinga closed confilling thereirnand electric ignition means to estainer of actinic light-transmitting material, a gas-filling therein, electric ignition means to establish a gas reaction in said gas-filling, substantialiy the whole actinic effect of the lamp being due to the gas reaction, and an electric fuse in said lamp in series arrangement with said electric ignition means the gas pressure during said reaction being too low to cause rupturing of the container.

13. A flashlight lamp comprising a closed container of aetinic light-transmitting material, a gas filling therein, electric ignition means to establish a gas reaction in said gas filling, substantally the whole actinic efiect of the lamp being dueto the gas reaction, a tube connected to said container and provided with an aperture, resilient means to close said aperture when the pressure inside of the container is lower than the pressure outside thereof, and to open said aperture when the pressure inside 01 the container is greater than on the outside.

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