US3473880A

US3473880A - Multiple flash bulb holder

Info

Publication number: US3473880A
Application number: US567008A
Authority: US
Inventors: Richard Wick
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1965-07-30
Filing date: 1966-07-21
Publication date: 1969-10-21
Anticipated expiration: 1986-10-21
Also published as: BE684690A; DE1296520B; GB1103682A; NL6610619A

Description

4 Sheets-Sheet l IN V EN TOR. RICHARD WICK @EL 21, R W|CK MULTIPLE FLASH BULB HOLDER Filed July 2l, 1966 2. .wm m. F

UCL 21, 1969 R, W'CK MULTIPLE FLASH BULB HOLDER 4 Sheets-Sheet 2 Filed July 2l. 1966 IN V EN TOR.

RICHARD WICK 0d. 21, 1969 R, WICK' 3,473,880

MULTIPLE FLASH BULB HOLDER Filed July 2l, 1966 4 Sheets-Sheet 5 F ig.5 75a IN VEN TOR. RICHARD WICK Oct. 21, 1969 R, WICK MULTIPLE FLASH BULB HoLDER 4 Sheets-Sheet 4 Filed July 2l, 1966 INVENTOR. RICHARD WICK Cl. 431-95 12 Claims ABSTRACT 0F THE DISCLOSURE A multiple flash bulb holder with a series of discrete flash bulbs each having two main contacts connected to each other by a filament which is destroyed on firing of the respective flash bulb. The electric circuit of the holder comprises normally open switches installed in the flash bulbs and arranged to close in response to firing of the respective flash bulbs to thereby prepare the next-following bulb for firing. Each switch is connected in series between one of two terminals in the electric circuit and one main Contact of the respective flash bulb. The other main contact of each flash bulb is connected to the other terminal.

The present invention relates to flash units in general, and more particularly to an improved multiple flash bulh holder which may be utilized in a photollash unit. Still more particularly, the invention relates to a multiple flash bulb holder whose dash bulbs can lbe red in `a predetermined sequence.

It is already known to provide a holder with two or more flash bulbs and to utilize a multi-stage switch for firing the flash bulbs in a desired sequence. It is also known to replace the multi-stage switch with a series of resistors having different resistances. Such holders must be provided with complicated and expensive electric circuits.

Accordingly, it is an important object of the present invention to provide a novel and improved multiple flash bulb holder wherein the flash bulbs are automatically fired in a given sequence and wherein such sequential firing can be insured by resorting to a very simple and inexpensive electric circuit.

Another object of the invention is to provide a multiple flash bulb holder wherein only one of several flash bulbs can be connected in the flash circuit at a time and wherein sequential firing of flash bulbs requires no changes Y tical number of flash bulbs and wherein such flash bulbs can be arrayed in a number of different ways.

An additional object of the invention is to provide a novel system of very simple switches which can be utilized in the flash bulbs of my improved holder and which can be actuated in automatic response to changes in temperature which develop when the respective flash bulb is fired to thereby prepare the next flash bulb for firing.

A concomitant object of the invention is to provide the flash bulbs of my improved holder with novel circuit completing means which react automatically to firing of such flash bulbs and which, if desired, may be constructed and assembled in such a way that their operation is insured in any desired position of inclination of the holder.

A further object of the invention is to provide a multiple flash bulb holder wherein the flash bulbs can be fired hired States arent 0 Patented Oct. 21, 1969 ICC in a predetermined sequence and which functions properly irrespective of the magnitude of firing voltage and irrespective of the internal resistance of individual flash bulbs.

Briefly stated, one feature of my invention resides in the provision of a multiple flash bulb holder whose housing is preferably provided with a standard foot so that it can be introduced into a standard socket forming part of a flash unit which is built into or is usable in connection with a photographic camera. The holder comprises a plurality of flash bulbs each of which is preferably accommodated in a separate recess of the housing, these flash bulbs including a first and at least one second flash bulb, and the holder further comprises an electric circuit at least a portion of which may be printed directly onto the housing. This circuit has a pair of terminals which are connectable with a source of electrical energy and normally open switch means preferably provided in the envelope of the first flash bulb and arranged to close permanently in response to firing of the first flash bulb to thus prepare the second flash bulb for firing.

In accordance with a more `specific feature of my invention, each flash bulb comprises a first and a second main contact and a filament which connects the two main contacts and is destroyed in response to firing of the respective flash bulb. The first main contacts of all flash bulbs are connected to one terminal of the aforementioned circuit and the second main contact of the first flash bulb is connected with the other terminal so that, when the circuit is completed, the filament of the first flash bulb will be destroyed. The first flash lbulb further cornprises an auxiliary contact which is normally insulated from the second main contact of the first flash bulb and is connected with the second main contact of the second flash bulb. The first flash bulb also comprises circuit completing means for connecting its second main contact with the auxiliary contact in response to firing of the first flash bulb whereby the second main contact of the second flash bulb is automatically connected with the second terminal.

The circuit completing means may include a body of current-conducting material which melts or expands strongly at firing temperature, or such means may include a resilient element of current-conducting material which tends to engage the auxiliary contact and is free to do so when the filament of the first flash bulb is destroyed.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved multiple flash bulb holder itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat schematic front elevational view of a multiple flash bulb holder with four flash bul-bs which is constructed in accordance with a first embodiment of my invention;

FIG. 2 is an enlarged transverse vertical section as seen in the direction of arrows from the line II-II of FIG. 1;

FIG. 3 is a front elevational view of a modified multiple flash bulb holder with six flash bulbs;

FIG. 4 is a perspective view of -a still camera having a builtir1 flash unit which comprises a standard socket receiving the foot of the multiple flash bulb holder shown in FIG. 3;

FIG. 5 illustrates a portion of a flash circuit including the circuit of the holder shown in FIGS. 1 and 2;

FIG. 6 is a fragmentary axial section through a flash bulb which is provided with a first type of circuit completing means including a body of fusible currentconducting material;

FIG. 7 is a similar fragmentary axial section through a second flash bulb whose circuit completing means comprises a resilient element; and

FIG. 8 is a fragmentary axial section through a third flash bulb Whose circuit completing means comprises a body of current-conducting material which expands in response to heating.

Referring first to FIGS. l and 2, there is shown a multiple flash bulb holder comprising a relatively flat housing or support 1 which may consist of synthetic plastic material. The front face of the support 1 is provided with a row of four

recesses

2, 3, 4 and 5 which respectively accommodate

flash bulbs

6, 7, 8 and 9. The surfaces bounding the recesses 2-5 may be coated with strongly light-reflecting or light-dispersing metallic material which is sprayed onto the housing 1 or is applied in the form of a foil or the like. Each such layer or foil then forms a reflector which can reflect artificial light against the subject when the circuit of the respective flash bulb is completed. If desired, the surfaces bounding the recesses 2-5 may be formed with depressions and/or raised portions to further enhance their light reflecting and dispersing action.

Each of the flash bulbs 6-9 comprises an envelope `which accommodates two

main contacts

11, 12 connected to each other by a filament 10, and a third or auxiliary contact 13.

The housing 1 is also provided with a foot or plug 1a carrying two terminals 14, which are glued or other- Wise affixed to its front and rear surfaces, respectively. The dimensions of the foot 1a preferably equal the dimensions of a standard foot on a conventional multiple flash bulb holder so that this foot can be readily inserted into a standard socket of a photographic camera.

The base 1b of the housing 1, which extends between the upper portion 1c (provided with the aforementioned recesses 2-5) and the foot 1a, carries the conductors or leads of an electric circuit which is preferably a printed circuit and is provided in part at the front side and in part at the rear side of the base 1b. The leads of this printed circuit are connected with the contacts 11-13 of the flash bulbs 6-9 and with the

terminals

14, 15 in a manner as illustrated in FIG. 1. A first lead 1b connects the front terminal 14 with the main contacts 11 of the four flash bulbs 6-9. A second lead 17 connects the rear terminal 15 with the main Contact 12 of the first (leftmost) flash bulb 6. Additional leads 18-20 respectively connect the auxiliary contacts 13 of

flash bulbs

6, 7, 8 with the main contacts 12 of the

flash bulbs

7, 8, 9. The auxiliary contact 13 of the last (rightmost) flash bulb 9 is not connected in the circuit at all and is provided solely because the flash bulbs 6-9 are preferably identical with each other to reduce the manufacturing cost. This last flash bulb 9 can be replaced by a conventional flash bulb having a pair of contacts corresponding to the

main contacts

11, 12 of any one of the flash bulbs 6-9. The leads 16 and 18-20 are provided at the front side of the base 1b and are shown in FIG. l by solid lines. rIhe lead 17 is provided at the rear side of the base 1a and is shown in FIG. 1 by broken lines.

The function of the auxiliary contacts 13 is to automatically connect a next-following

flash bulb

7, 8, 9 in circuit with the

terminals

14, 15 in response to firing of the preceding

flash bulbs

6, 7, 8 respectively. In other words, and when the first flash bulb 6 is fired, its main contact 12 is conductively connected with the auxiliary contact 13 and hence with the lead 18 and main contact 12 of the next-following flash bulb 7. The rear terminal 15 is then connected with the main contact 12 of the flash bulb 7 through the lead 17,

contacts

12, 13 of the flash bulb 6, and lead 18. The front terminal 14 is con- 4 nected with the main contact 11 of the flash bulb l through the lead 16.

When the flash bulb 7 is fired, its

contacts

12, 13 automatically connect the terminal 14 with the contact l2 of the flash bulb 8 through the

contacts

12, 13 of the spent flash bulb 6. In response to ignition of the bulb its

contacts

12, 13 connect the main contact 12 of the last flash bulb 9 with the rear terminal 15 through the

contacts

12, 13 of the

spent flash bulbs

6 and 7. In other words, each preceding

flash bulb

6, 7, 8 has a built-

in switch

12, 13 which closes in automatic response to firing of the respective flash bulb to connect one main contact 12 of the next-following

flash bulb

7, 3, 9 with the rear terminal 15. The

switches

12, 13 of all spent flash bulbs are connected in series by the

leads

1S, 19, 20. The other main contact 11 of each flash bulb is directly connected with the front terminal 14 by the lead 16. The manner in which the

aforementioned switches

12, 13 close in response to firing of a

flash bulb

6, 7 or S will be describen in connection with FIGS. 6, 7 and 8. The filaments 10 are destroyed in response to firing of the respective flash bulb and terminate the current-conducting connection between the corresponding

main contacts

11, 12.

If the multiple flash bulb holder of FIG. 1 is attached to a still camera (for example, to a camera of the type shown in FIG. 4), its foot 1a enters the socket of the camera and the

terminals

14, 15 engage suitable complementary contacts in the flash circuit of the camera. Such flash circuit comprises a customary synchronizing switch and one or more sources of electrical energy ano can be completed in response to actuation of a release trigger for the shutter. The aforementioned socket may be built into or may be detachably mounted on the camera. In response to a first actuation of the release trigger Sila (see FIG. 4), the flash circuit is completed and the first flash bulb 6 is fired to illuminate the subject. Such firing results in destruction of the filament 10 and in closing of the

switch

12, 13 which connects the main contact 12 of the second flash bulb 7 with the rear terminal 15 through the intermediary of the lead 18. During the next actuation of the trigger 30a, the flash circuit is completed again and fires the second flash bulb 7 which illuminates the subject with attendant destruction of its filament 10 and closing of its

switch

12, 13. The switch is connected tn series with the

switch

12, 13 of the spent flash bulb e and the two switches connect the main contact 12 of the next-following fresh flash bulb 8 with the rear terminal 15. The main contact 12 of the last flash bulb *t is connected with the terminal 15 in response to closing of

switches

12, 13 in all of the preceding flash bulbs b. 7 and 8.

Referring again to FIG. 2, the front sides of the four recesses 2-5 in the upper portion 1c of the housing 1 are closed by a transparent covering or panel 21 of synthetic plastic sheet material which is glued or otherwise affixed to the housing. This panel 21 prevents escape of fragments of envelopes if a flash bulb happens to break. Also, the panel 21 preferably overlies the leads 16 and 18-20 at the front side of the base 1b to protect such leads from damage. The entire multiple flash bulb holder forms a self-contained unit which can be mass-produced and can be readily manipulated by unskilled amateurs. The covering 21 protects the flash bulbs so that the holder of FIGS. 1 and 2 can be manipulated by hand and stored in unpadded boxes Without any danger of damage or breakage.

FIG. 3 illustrates a modified multiple flash bulb holder which is provided with six recesses 22a-27a disposed in two groups and each accommodating one of six flash bulbs 22-27. The housing 28 of this holder comprises a standard foot 28a with terminals 14', 15. The printed circuit includes front leads which are shown by solid lines and rear leads shown by broken lines. The manner in which the switches 12', 13 of spent flash bulbs can connect the main Contact 12' of the next-following (unexpended) ash bulb with the front terminal 14' is selfexplanatory. lt is clear that the multiple iiash bulb holder of my invention may comprise only two or three ash bulbs as well as live, seven or even more flash bulbs, and that such dash bulbs may be distributed in any desired way, i.e., in one or more horizontal or vertical rows, in the form of a full circle or semicircle, in the form of a cross or star, or in any other array which does not take up too much space.

In this embodiment of my invention, the lead 16 which is connected with all of the main contacts 11 is provided at the rear side of the housing 28 and is connected to the terminal Referring now to FIG. 4, there is shown a still camera whose casing 3l) has a top wall 30h provided with a standard socket 29 for the foot 28a of the housing 28. The socket 29 is partially surrounded by a reliector 31 which is preferably depressible so that it can be concealed in the casing 30. This reflector 31 can be coupled with a suitable ejector (not shown) which expels the foot 28a from the socket 29 in automatic response to depression of the reflector 31. It will be seen that the foot 28a is long enough to allow for movement of the reflector 31 to its fully exposed position so that the aforementioned ejector is idle. Such relatively long foot allows for attachment of the improved multiple flash bulb holder to cameras whose reliectors 31 are dimensioned for use in connection with much smaller holders, for example, those known as Flashcubes, or in connection with individually insertable liash bulbs. The number of ilash bulbs in the housing 28 can be selected independently of the size of the reiiector 31 because the latter does not reach that (upper) part of this housing which accommodates the ash bulbs.

FlG. 5 illustrates the ash circuit of a camera which can utilize the improved multiple flash bulb holder, for example, the holder which was described in connection with FlGS. l and 2. This lash circuit includes a customary charging capacitor C1 which can be installed in the camera proper or in a detachable flash unit. The capacitor C1 can be charged through a resistor R which is connected in series with a source of electrical energy here shown as a battery 32. The release trigger of the camera can close a normally open switch S to connect the battery 32 in circuit with the first iiash bulb 6. The terminals in the socket of the camera are shown at 14a, 15a and are respectively engaged by the

terminals

14, 15 on the foot of the housing which accommodates the liash bulb 6.

The capacitor C1 discharges in response to closing of the switch S to iire the ash bulb 6 and to destroy the filament 10. In response to such destruction of the lament 10, the

switch

12, 13 of the spent ash bulb 6 closes and connects the terminal 15 with the main contact 12 of the second ash bulb 7 through the lead 18. The capacitor C1 is recharged on opening of the switch S and, when the switch S is closed again, renewed discharge of the capacitor C1 results in :tiring of the ash bulb 7 so that the lament 10 of this iiash bulb is destroyed and the

switch

12, 13 of the liash bulb 7 connects the terminal 15 with the main contact 12 of the third ash bulb 8 (not shown in FIG. 5) in the same way as described in connection with FIG. l, i.e., through the leads 17-19 and the

switches

12, 13 of the spent

ilash bulbs

6 and 7.

The additional or supplementary capacitors C2, C3 shown in FIG. 5 prevent premature iiring of the

ash bulbs

7, 8 by the remaining charge of the capacitor C1. The capacitors C2, C3 are connected in parallel with the

flash bulbs

7, 8, and a similar capacitor (not shown) is connected in parallel with the fourth and last liash bulb 9. These supplementary capacitors can intercept the major part of surplus current impulse developing on discharge ot' the capacitor C1 and thus prevent such iiow of current which would cause iiring of the associated

ash bulb

7, 8 or 9 simultaneously with tiring of the preceding lash

bulb

6, 7 or 8.

Care should be taken to insure that the duration of the tiring impulse should not exceed the time necessary for closing of the switch in the iiash bulb which is being red, i.e., that the switch S opens before the capacitor C1 discharges again to re the next-following liash bulb. Such opening of the switch S takes place automatically in presently known flash units which utilize one or more charging capacitors.

FIG. 6 shows one embodiment of a ash bulb whose switch (including a main contact 38 and an auxiliary contact 40) closes in automatic response to tiring and resultant destruction of the iilament 36. The iiash bulb comprises an envelope 35 of vitreous material and a second main contact 37 which is connected with the main contact 38 by the iilament 36. The interior of the envelope 35 further accommodates a smal] receptacle 39 which preferably consists of vitreous or ceramic material and does not conduct electric current. As clearly shown in FIG. 6, the cavity or chamber 39a of the receptacle 39 accommodates the bulbous head 41 of the auxiliary contact 40 and a portion of the adjoining main contact 38. The head 41 consists of a material which melts at temperatures developing in the chamber 39a in response t0 tiring of the ash bulb. For example, the head 41 may consist of a body of tin solder or silver solder. In order to insure that melting of the head 41 will invariably result in establishment of a current-conducting connection between the

contacts

38 and 40, the head may be surrounded by a layer of ux. As soon as the temperature in the cavity 39a reaches the melting temperature of the material of which the head 41 consists, the latter begins to melt and forms a pool 39]: in the bottom zone of the cavity and establishes a -connection between the

contacts

38 and 40. The receptacle 39 prevents shortcircuiting of the flash bulb prior to firing by holding the

contacts

37, 38 and 4G in the regions which are closely adjacent to their upper ends. Short-circuiting of the ash bulb by remnants of the metallic filler (not shown) in the envelope 35, which ller is destroyed on tiring of the ash bulb, can be prevented by providing the contact 37 with a coat of insulating material. Such insulating coat also prevents accidental shorting by the wires of the iiller prior to actual tiring ofthe flash bulb.

lf desired, the receptacle 39 can be formed as an integral part of the envelope 35, for example, as an integral part of the base 35a. However, the provision of a separate receptacle 39 which holds the free end portions of the

contacts

37, 38, 40 apart is normally preferred because the receptacle then prevents accidental shorting.

FIG. 7 illustrates a modied iiash bulb having an envelope 42 of vitreous material, two

main contacts

43, 45 connected to each other by a iilament 44, and an auxiliary contact 47 having a pointed head 48. The upper portion of the main Contact 45 is constituted by a leaf spring 46 which stores energy when the lament 44 is intact. When the filament 44 is destroyed in response to firing of the flash bulb, the spring 46 moves to its unstressed position and engages the head 48 to close the switch which includes the contacts 45 and 47. The solution shown in FIG. 7 is often preferred over that which was described in connection with FIG. 6 because the spring 46 can close the switch 45, 47 regardless of the position of inclination in which the envelope 42 is held at the time the flash bulb is tired. The spring 46 may be welded, riveted or otherwise conductively connected with the Iemainder of the main conductor 45. The length of the lament 44 is selected in such a way that the spring 46 remains deformed as long as the iilament remains intact, i.e., the main contact 43 must be rigid or its flexibility must be less than that of the spring 46 so that the spring invariably remains spaced from the head 48 as long as the circuit of the

contacts

43, 45 is not completed. The normal position of the spring 46 is preferably selected in such a way that this spring actually bears against the 7 head 48 when the filament 44 is destroyed so that the spring does not move away from the head 48 even if the multiple flash bulb holder embodying the ash bulb of FIG. 7 is shaken or otherwise agitated subsequent to firing of the flash bulb.

Referring finally to FIG. 8, there is shown a third flash bulb whose envelope 49 accommodates two main contacts 55, 56 and an auxiliary contact 54. The lower portion of the envelope 49 defines a preferably cylindrical cavity or chamber 50 which accommodates the pointed tip 54a of the auxiliary contact 54 and an intermediate portion of the main contact '55. The upper end of the chamber 50 is sealed from the remainder of the internal space of the envelope 49 by a fixed stopper or cork 51. This stopper 51 is adjacent to the upper side of a mercury drop 53 whose underside is adjacent to a vertically movable separator here shown as a diaphragm 52 preferably consisting of readily penetrable soft plastic material. The diaphragm 52 rests on the tip 54a of the auxiliary contact 54. The median portion of the main contact 55' eX- tends through the chamber 50 and passes through the diaphragm 52, drop 53 and stopper 51. The lupper'end portion of the main contact 55 is connected with the main contact 56 by a filament 57. The mercury drop 53 expands in response to rising temperature which develops on firing of the flash bulb. The expanding drop 53 pushes the diaphragm 52 against the tip 54a whereby the tip penetrates the diaphragm and comes in contact with mercury to thus close the switch including the contacts 54 and 55. As stated before, the drop 53 is in permanent contact with the main'contact 55. The well known phenomenon of surface tension insures that the switch 54, 55 remains closed even after the temperature of mercury drops.

Without further analysis, the foregoing will so fully reveal the -gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is: t

1. A multiple flash bulb holder, comprising a plurality of discrete flash bulbs including a first and a second ash bulb, each of said flash bulbs comprising separate first and second main contacts, a filament connecting said main contacts and arranged to undergo destruction in response to firing of the respective liash bulb, and a separate envelope surrounding said main contacts and said filament; an electric circuit having a pair of terminals connectable with a source of electrical energy and normally open switch means comprising two contacts and arranged to close permanently in response to firing of said first flash bulb to thus prepare said second iiash bulb for firing, each of said first main contacts being connected with one of said terminals and the second main contact of said first ash bulb being connected with the other terminal, said switch means being connected between the second main contacts of said first and second flash bulbs; and circuit completing means for connecting the contacts of said switch means to each other in response to firing of said first flash bulb, said circuit completing means comprising a body of current-conducting material provided on one contact of said switch means, said material being fusible at firing temperature of said first flash bulb to thereby establish a current-conducting connection between the contacts of said switch means.

' 2. A holder as set forth in claim 1, wherein the contacts of said switch means comprise closely adjacent portions and said body of current-conducting material is provided on such portion of said auxiliary contact.

3. A holder as set forth in claim 1, wherein said circuit completing means further comprises a receptacle consisting of heat-resistant material and having a chamber arranged to collect said current-conducting material in response to fusing of said body, each contact of said switch g means comprising a portion extending into said chamber so that the fused body connects such portions.

4. A holder as set forth in claim 3, wherein said receptacle consists of a material selected from the group consisting of vitreous and ceramic substances.

5. A multiple flash bulb holder, comprising a plurality of discrete ash bulbs including a rst, a second and a third flash bulb, each of said ash bulbs comprising a separate first main contact, a separate second main contact and a filament connecting said main contacts and arranged to undergo destruction in response to firing of the respective flash bulb; and an electric circuit having a pair of terminals connectable with a source of electrical energy andL normally open first and second switch means respectively arranged to close permanently in response to ring of said first and'second flash bulbs, each of said first main contacts b eing connected wit-hone of said terminals and the second main contact of said first flash bulb being connected with the other terminal, said first switch means being connected between the second main contacts of said first and second flash'bulbs so that said second fiash bulb can be red subsequent to firing` of said first ash bulb and onresultingclosing of said first switch means, said second switch means being connected between the second main contacts of said second and third ash bulbs so that said third iiash bulb can be fired upon firing of said second ash bulb and on resulting closing of said second switch means, the second main contact of said third ash bulb being then connected with said other terminal by way of said first and second switch means.

6. A multiple ash bulb holder as defined in claim 5, wherein each of said flash bulbs comprises a separate envelope.

7. A-multiple ash bulb holder as defined in claim e', wherein each of said switch means comprises a pair or contacts and further comprising circuit-completing means for respectively connecting the-contacts of said first and second switch means to each other in response to firing of said first andsecond fiash bulbs;

8. A multiple ash bulb holder as defined in claim 7, wherein said circuit completing means comprises a resilient element of'current-conducting material provided on the second main contact of each of said first and second flash bulbs and permanently tending to engage one contact of said first and second switch means respectively, each of said resilient elements being held away from said one contact of the respective switch means bythe filament of'said rst and. second Hash bulb respectively and being free to engage the respectiveone contact in response to destruction of thegcorresponding filament.

9. A multiple flash bulb holder as defined in claim 7, wherein said circuit completing means comprises bodies of current-conducting material each being in permanent contact with one contact of said first and second switch means and being expansible in response to-a rise in temperature on firing of said ,first andV second ash bulb respectively to thus establish a current-conducting connection between said one contact and the other contact of the respective switch means. l

10. A multiple liiash bulb holder as defined in claim 9, wherein'each of said bodies consists of mercury.

11. A multiple flash bulb holder, as defined in claim 10, wherein each of said first `and second ash bulbs comprises an envelope defining a chamber for the respective body, said circuit completing means ,further comprising a pair of'separator means each consisting Iof readily penetrablematerial and disposed between one of said bodies and a pointed portion of the other contact of the respective switch means so that, when one of said bodies expands, the pointed portion of 4the other lcontact of the respective switch meanspenetrates through the corresponding separator and moves intoA current-conducting engagement with mercury, said bodies being respectively in permanent current-conducting contact with the second main contacts of said first and second liash bulbs.

12. A multiple flash bulb holder, comprising a plurality of ash bulbs including a rst and a second ash bulb, each of said flash bulbs comprising a rst main contact, a second main contact and a iilarnent connecting said main contacts and arranged to undergo destruction in response to tiring of the respective ash bulb; and an electric circuit having a pair of terminals connectable with a source of electrical energy, said rst main contact of each ash bulb being connected with one of said terminals and the second main Contact of said rst flash bulb being connected with the other terminal, normally open switch means arranged to close permanently in response to tiring of said rst flash bulb to thus prepare said second ilash bulb for tiring, said switch means comprising the second main Contact of said rst ilash bulb and an auxiliary contact which is normally insulated from said last named Second main contact and is connected with the second main contact of said second ash bulb, circuit completing means for connecting the contacts of said switch means to each other in response to ring of 20 said rst flash bulb, a charging capacitor connected in 10 parallel with the main contacts of said first ash bulb, a source of electrical energy connected in circuit with said charging capacitor, and a second capacitor connected in parallel between the main contacts of said first and second Hash bulbs, the capacitance of said second capacitor being less than that of said rst capacitor.

References Cited UNITED STATES PATENTS 2,191,402 2/1940 Sair et al. 431-93 X 2,290,309 7/ 1942 Aquilla 431-93 2,817,963 12/1957 Scholkemeier 431-93 3,220,225 ll/1965 Baird 431-95 FOREIGN PATENTS 1,192,047 4/ 1965 Germany.

EDWARD 3'. MICHAEL, Primary Examiner US. Cl. X.R.