US3745896A

US3745896A - Flash apparatus

Info

Publication number: US3745896A
Application number: US00082338A
Authority: US
Inventors: G Sperti; A Gerth
Original assignee: St Thomas Institute
Current assignee: St Thomas Institute
Priority date: 1970-10-20
Filing date: 1970-10-20
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17

Abstract

Flash apparatus for use with camera equipment and the like, comprising a lamp connected across a power source and a circuit to cause current to flow through the lamp so as to bring the lamp to full brilliance simultaneously with, or immediately prior to, the opening of the camera shutter. The last mentioned circuit may comprise a timing circuit the operation of which is initiated by a trigger switch. The trigger switch may be built into the flash apparatus or it may be of the remote type. A circuit may also be provided whereby the lamp may be operated at less than full brilliance prior to the opening of the camera shutter.

Description

United States Patent 1 Sperti et al.

11 3,745,896 [451 July 17,1973

[ FLASH APPARATUS [75] Inventors: George S. Sperti; Albert E. Gerth,

both of Cincinnati, Ohio Related US. Application Data [63] Continuation-impart of Ser. No. 672,618, Oct. 3,

8/1959 Most 315/241 P X 2,877,385 3/1959 Rock 315/241 P X 1,988,022 1/1935 Smith 3,259,797 7/1966 Heine 315/247 X Primary ExaminerSamuel S. Matthews Assistant Examiner-Monroe H. Hayes Attorney-Melville, Strasser, Foster & Hoffman [57] ABSTRACT Flash apparatus for use with camera equipment and the like, comprising a lamp connected across a power source and a circuitto cause current to flow through the lamp so as to bring the lamp to full brilliance simultaneously with, or immediately prior to, the opening of the camera shutter. The last mentioned circuit may comprise a timing circuit the operation of which is initiated by a trigger switch. The trigger switch may be built into the flash apparatus or it may be of the remote type. A circuit'may also be provided whereby the lamp may be operated at less than full brilliance prior to the opening of the camera shutter.

15 Claims, 27 Drawing Figures PAFENEED 1 75m 3. 745.896

sum 2 OF 5 Fi g. 10

I NVENTOR/S GEO/20E S. SPERT/c? ALBERT E. GERTH,

XTTORNEYS PAIEN'IEB JUL 1 7 I975 SHEET 3 BF 5 1 l c A 76 2 79 Fig. 19

INVENTORE'S GEORGE 5. SPERTI ALBERT E. GERTH ATTORNEYS PATENIEBJUL 1 H975 3 [45, 896

SHEET N [If 5 lNVENTOR/S GEORGE 5. SPERTI ALBERT E, GERTH BY L%(IJJFI, fllla Wild/1 ATTORNEYS PATENTEUJUI 17mm SHEET 5 OF 5 INVENTOR/S GEORGE s SPERTI ALBERT E GERTH FLASH APPARATUS CROSS REFERENCE TO THE RELATED APPLICATION This is a continuation-in-part application of US. Pat. application Ser. No. 672,6l8 filed Oct. 3, 1967, in the name of the same inventors, George S. Sperti and Albert S. Gerth, and entitled FLASH APPARATUS.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to flash apparatus and circuitry therefor, and more particularly to flash apparatus for use with camera equipment and the like.

2. Description of the Prior Art Heretofore illumination of the subject matter in photographic procedures has been accomplished in a number of ways. For example, flash bulbs of numerous well known types have been employed. Such bulbs are capable of a single use only, and are intended to be disposable.

Flash means have also been provided which are capable of a plurality of uses. Such flash means are generally provided with a storage means for electrical energy and are rechargeable with a given number of flashes obtainable per charge.

An additional well known source of subject matter illumination is the photoflood lamp. One or-more of 7 these lamps may be used to light the subject matter, but they operate at maximum brilliance at all times, are unpleasant to the eyes and are characterized by a relatively short life.

In certain embodiments of the present invention the photoflash arrangement utilizes one or more incandescent lamps connected to a power source. Means may be provided for operating the incandescent lamp or lamps at an initial low-voltage, low-filament temperature level. Additional means are provided for operating the lamp or lamps at a high voltage, operating filament temperature level at the time the camera shutter is opened.

Operating the lamp or lamps at the initial level accomplishes several purposes. The lamps will be at partial brilliance, which is not only comfortable to the eye, but which will provide pre-photograph illumination of the subject so that the proper arrangement of lights, shadows and the like may be achieved. In addition, the operation of the lamp or lamps at the initial low level will cause them to warm up so that full brilliance may be reached immediately. If, for example, the lamps were started from a cold condition at the time the camera shutter was opened, too great a length of time would be required to bring them to full brilliance. Operating the lamps at an initial low-voltage level, and preheating them thereby, prevents mechanical shock to the filaments when full voltage is applied. In this'way, lamp life may be increased or lamps characterized by even shorter life but greater brilliance may be used. In accordance with the present invention an incandescent lamp or lamps may be flashed at an extremely high brilliance over and over again.

In another embodiment a xenon or other gaseous arc lamp is used. A first low voltage is applied to the lamp to cause it to illuminate when a second high voltage, serving as an ignition voltage, is applied to the lamp substantially simultaneously with the opening of the camera shutter.

A timing circuit may be provided in either the incandescent or are lamp embodiments so that the lamp is operated at full brilliance for a proper time duration independent of the time for which the trigger switch is held closed. As will be shown hereafter, the timing circuit provides a number of advantages including the prolonging of lamp life.

The present invention provides means whereby an incandescent or are lamp may be used in a flash apparatus over and over again. The lamp is connected directly across the power source (such as a household outlet or the like) and the need for a storage means for electrical energy and the usual time-consuming recharging step has been obviated.

SUMMARY OF THE INVENTION The embodiments of the flash apparatus of the present invention comprise at least one arc or incandescent lamp and means to operate the lamp at full brilliance substantially simultaneously with the opening of the camera shutter. By substantially simultaneously, as used here and in the claims, is meant that the lamp is brought to full brilliance simultaneously with or immediately prior to the opening of the shutter.

The flash apparatus of the present invention may also be provided with a timing circuit to remove power from the lamp or lamps as quickly as possible. The invention also relates to means whereby the triggering switch may be actuated directly, or indirectly, by electrical, hydraulic or pneumatic means.

It will be understood by one skilled in the art that the flash apparatus of the present invention may be fabricated in any suitable form. For example, the flash apparatus may comprise a unit which is an integral or detachable part of the camera itself, or the unit may comprise a completely self-contained, wholly separate apparatus. In addition, the flash apparatus of the present BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of the flash apparatus of the present invention illustrating a resistor in series with the lamp, and a triggering switch by which the resistance may be by-passed.

FIG. 2 is-a circuit diagram similar to FIG. 1 illustrating the use of a rectifier means.

FIG. 3 is a circuit diagram similar to FIG. 2 showing a resistor in series with the rectifier means.

FIG. 4 is a circuit diagram similar to FIG. 2 illustrating the use of a silicon controlled rectifier and an exemplary form of triggering circuit.

FIG. 4a is a circuit diagram similar to FIG. 4 but illus trating another form of triggering circuit.

FIG. 5 is a circuit diagram similar to FIG. 3 illustrating the use of a silicon controlled rectifier as a part of the triggering mechanism.

FIG. 6 is a circuit diagram of the flash apparatus of the present invention wherein two lamps are connected in series until triggering, at which time the lamps are switched to a parallel connection.

FIG. 7 is simialr to FIG. 6 and shows the use of a resistorin series with the lamps.

FIG. 8 is a circuit diagram showing a silicon controlled rectifier as the sole series element with the lamp.

FIG. 8a is a circuit diagram similar to FIG. 8 but illustrating the use of a silicon controlled switch.

FIG. 9 is a circuit diagram wherein four rectifier elements comprise a bridge circuit in series with the lamp. A silicon controlled rectifier is included, whereby the rectifier bridge may be short circuited over the conduction phase angle.

FIG. 10 is an electrical diagram of the flash apparatus of the present invention illustrating the use of a timing circuit.

FIGS. 11 and 12 are respectively perspective and cross sectional views of the hand actuated portion of an hydraulic or pneumatic means for remotely actuating a trigger switch.

FIGS. 13 and 14 illustrate respectively two exemplary forms of a triggering switch with pneumatic or hydraulic means for actuating them.

FIG. I is an exploded view of a portion of a finger actuated triggering switch.

FIG. 16 is a cross sectional view of the finger actuated triggering switch showing the elements of FIG. 15 in final assembly.

FIG. 17 is an electrical diagram similar to that of FIG. but without the pre-flash illumination means.

FIGS. I8 and 19 are similar to FIG. 10 but illustrate alternate embodiments of the timing circuit.

FIG. 20 is an electrical diagram somewhat similar to the circuit of FIG. 10 and illustrating the use of a gaseous arc lamp and a timing circuit.

FIGS. 21 and 22 are similar to FIG. 20 but illustrate alternate embodiments of the timing circuit.

FIG. 23 is an electrical diagram illustrating another embodiment of the present invention utilizing an arc lamp and a timing circuit.

FIGS. 24 and 25 are electrical diagrams similar to that of FIG. 23 but illustrating alternate forms of timing circuits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the flash apparatus of the present invention in one of its simplest forms. A lamp 1 is connected by

leads

2 and 3 to a source of current as at 4. The source of current may be, for example, ordinary house current. In such an instance, the

leads

2 and 3 may terminate in a conventional two-pronged plug adapted to be received in a conventional wall socket.

The lamp 1 is connected in series with a resistor 5. The resistor 5 may be so chosen as to limit the voltage at the lamp terminals to slightly less than half voltage. Thus, when the lamp I is simply connected to a source of house current or the like, it will glow with a brilliance which is comfortable to the eyes, but which is sufficient for the photographer to determine the position of lights, shadows and the like. A triggering switch 6 is connected in parallel with the resistor 5. The triggering switch is adapted to be closed at the time the camera shutter is opened, so that during the interval in which the photograph is being taken, the resistor 5 is shorted or by-passed and full line voltage appears across the lamp terminals. When the device is connected to ordinary house current, which varies from 105 to 130 volts, the lamp may be designed to reach full brilliance at about 1 17 volts.

FIG. 2 is similar to FIG. I, and like parts have been given like index numerals. The circuitry of FIG. 2 differs from that of FIG. I in that a rectifier 7 is substituted for the resistor 5. The rectifier may be of any suitable type as, for example, a silicon diode rectifier. When the lamp is connected at 4 to a source of AC house current, the rectifier reduces lamp voltage by conduction of only one half cycle. Thus, the voltage at the lamp terminals will be slightly less than one half the full AC line voltage, or approximately 45 percent of the line voltage. During the interval when the photograph is being taken, the triggering switch 6 will be closed, shorting or by-passing the rectifier 7.

FIG. 3 is similar to FIG. 2, and again like parts have been given like index numerals. The circuit illustrated in FIG. 3 differs in that a resistor 8 is placed in series with the rectifier 7. In this way, the lamp voltage may be further reduced during the standby period. As an example, the resistor 8 may be chosen so as to reduce the lamp voltage by an additional twelve to fifteen volts.

FIG. 4 is substantially the same as FIG. 2 and like parts have been given like index numeral s. The circuitry of FIG. 4 differs from that of FIG. 2 in that the circuit includes a silicon or other controlled rectifier 9 connected in parallel with the rectifier 7. The silicon controlled rectifier 9 is adapted to allow current to flow in a direction opposite to the current flow through the rectifier 7 when a gate current is applied to the rectifier 9. The silicon controlled rectifier 9 may be connected to any suitable trigger circuitry and switch. An exemplary form of trigger circuitry may include a battery 10 of sufficient voltage to provide satisfactory gate potential, a switch 11 and a resistor Ila. When the switch 11 is closed, current limited to the noted value of the rectifier 9 by the resistor 11a will be supplied to the gate. Thus the switch 11 should be closed during the interval when a photograph is being taken, at which interval the lamp 1 will receive full line voltage minus the voltage drop over the rectifying element. The lamp 1 should be designed to reach full brilliance at such voltage.

FIG. 4a, wherein like parts have been given like index numerals, illustrates another exemplary form of trigger circuitry. In this instance the gate of the rectifier 9 is connected through switch II and resistor 11a to lead 3.

The circuit of FIG. 5 is substantially the same as that of FIG. 4 and like parts have been given like index numerals. As is generally indicated at 12, the silicon controlled rectifier 9 will be connected to any suitable form of trigger circuitry and switch. The trigger circuitry and switch can, for example, be the same as that illustrated in FIGS. 4 or 42. The primary difference be tween the circuitry of FIGS. 4 and 5 lies in the provision of the resistor 13, connected in series with the rectifier 7. The resistor 13 serves substantially the same purpose as the resistor 8 in FIG. 3. The resistor I3 is added to further reduce the voltage across the terminals of the lamp I during the standby period, thus further reducing the illumination during the standby period. In this arrangement the lamp 1, on triggering, will receive a lower average voltage than in the circuitry of FIG. 4 due to the asymmetrical wave form introduced by the resistor 13. For this reason, the lamp I of FIG. 5 should be designed to reach full brilliance at a somewhat lower voltage than would be the case of the lamp 1 in FIG. 4.

FIG. 6 is a circuit diagram for an embodiment of the present invention utilizing two lamps. It will be understood by one skilled in the art that the number of lamps used does not constitute a limitation on the present invention.

As shown in the figure, two lamps l4 and are connected respectively by leads 16 and 17 to a suitable source of current (generally indicated at 18) such as house current. The lamp 14 is connected by lead 19 to switch 20. The lamp 15 is connected by lead 21 to switch 22. One contact of each of the switches and 22 are interconnected by lead 23. Thus it will be noted that when switches 20 and 22 are in the position illustrated, the lamps l4 and 15 are connected in series. The other contact of switch 20 is connected to lead 17 by lead 24. Similarly, the other contact of switch 22 is connected to lead 16 by lead 25. Thus, when switches 20 and 22 are in their alternate position, it will be understood that the

lamps

14 and 15 will be connected in parallel.

The diagram of FIG. 6 also shows a relay 26 actuable by a trigger switch 27. The broken line 28 is used to diagrammatically indicate that switches 20 and 22 constitute a part of the relay 26. Thus, when the apparatus of FIG. 6 is connected to a source of electricity, as at 18,

lamps

14 and 15 will be in series during the standby pe riod. Also, the

lamps

14 and 15 during the standby period will glow with a brilliance which will not be discomforting to the eyes. At the time the camera shutter is opened and the photograph is taken, the relay 26, including

switches

20 and 22, will be actuated by the triggering switch 27. Actuation of the triggering switch 27, and hence switches 20 and 22, will cause the lamps to be connected in parallel, thus allowing full line voltage to appear across the terminals of each lamp.

FIG. 7 is similar to FIG. 6 and like parts have been given like index numerals. The circuit of FIG. 7 differs from that of FIG. 6 in that a resistor 29 is located in the lead 23 between

switches

20 and 22. The resistor 29 is connected in series with the lamps l4 and 15 during the standby period. In this way, the illumination of

lamps

14 and 15 during the standby period is further reduced. Actuation of switch 27, and hence switches 20 and 22, causes the lamps l4 and 15 to be connected in parallel, effectively removing the resistor 29 from the circuit and causing full line voltage to appear across the terminals of both lamps.

FIG. 8 illustrates another embodiment of the present invention. A lamp 30 is connected by

leads

31 and 32 to a source of electricity such as ordinary house current (generally indicated at 33). A silicon controlled rectifier 34 is located in lead 32 and may constitute the sole element connected in series with the lamp 30. A lead 35 is connected across leads 31 and 32 and contains a resistor 36, a resistor 37 and a capacitor 38 connected in series. Gate current is supplied to the silicon controlled rectifier 34 via lead 39 which, in turn, is com nected to lead 35. During the standby or pre-flash period, illumination of the lamp 30 is achieved by gate current reaching the silicon controlled rectifier 34. This gate current is governed by

resistors

36 and 37, capacitor 33, and a neon lamp 40 having a fixed firing voltage and located in lead 39. It will be understood by one skilled in the art that the neon lamp may be replaced by any of the solid state devices designed for this purpose, such as a break-over diode or the like. It will further be understood that during the standby or preflash period, the silicon controlled rectifier 34 will be triggered at a phase angle of conduction of less than A triggering switch 41 is provided, which when closed connects lead 39 to lead 35 in such a way as to by-pass resistor 37. Upon the closing of triggering switch 41, the lamp 30 receives rectified half-wave current (by virtue of the silicon controlled rectifier 34) and the lamp 30 is accordingly designed to reach full brilliance at this lower average voltage. During flashing, the phase angle of conduction is approximately 180.

It will be understood that, in the circuit diagram of FIG. 8, the resistor 36 will control the current reaching the gate of the silicon controlled rectifier during flashing. An adjustment of the gate current to the proper pre-flash level is accomplished by resistor 37. The circuit may also be provided with a diode rectifier 42, constituting a protective diode to insure that the back gate voltage will not exceed the limit of the silicon controlled rectifier 34.

FIG. 8a is similar to FIG. 8 and like parts have been given like index numerals. The circuitry of FIG. 8a difi'ers from that of FIG. 8 in that the silicon controlled rectifier 34 has been replaced by a silicon controlled switch 34a. The silicon controlled switch 340 will, when rendered conductive, permit the passage of alternating current, and may be the type sold by the General Electric Corporation under the trademark TRiAC. In this embodiment, the lamp 30 will receive full line voltage (minus the voltage drop over the silicon controlled switch) upon the closing of switch 41. Further, there is no need for a protective diode such as is shown at 42 in FIG. 8. The voltage drop over the silicon controlled switch is generally sufficiently small that a lamp designed to reach peak brilliance at full line voltage may be used with good results.

FIG. 9 shows an embodiment somewhat simlar to that of FIG. 8, but having the advantage that a lamp of normal design for full AC power may be used. In this instance, a lamp 43 is connected by

leads

44 and 45 to a source of current (which may be ordinary house current) generally indicated at 46. The lead 45 contains a bridge circuit (generally indicated at 47) in series connected with the lamp 43.

The bridge 47 comprises two leads 48 and 49. Lead 48 contains

rectifier elements

50 and 51.

Rectifier elements

50 and 51 are so oriented in lead 48 as to render lead 48 the positive side of the bridge. Lead 49 contains

rectifier elements

52 and 53.

Rectifier elements

52 and 53 are so oriented in lead 49 as to render the lead 49 the negative side of the bridge. The rectifier elements 50-53 may be diode rectifiers.

A lead 54 containing a silicon controlled rectifier 55 is connected across leads 48 and 49. A second lead 56, containing a first resistor 57, a second resistor 58 and a capacitor 59 is also connected across leads 48 and 49. Gate current is supplied to the silicon controlled rectifier 55 by means of a lead 60 connected to the lead 56. The lead 60 contains a neon lamp 61 of fixed firing voltage. A triggering switch 62 is also provided whereby the lead 60 may be connected to the lead 56 in such a way as to by-pass resistor 58.

It will be understood by one skilled in the art that in the absence of current passing through the silicon controlled rectifier 55, the bridge circuit containing rectifier elements 50-53 will block current to the lamp 43.

In the circuit of FIG. 9, the

resistors

57 and 58, the capacitor 59, and the neon lamp 61 serve the same function as the

resistors

36 and 37, the capacitor 38 and the neon lamp 40 in FIG. 8. When connection is made with a source of electricity at 46, the lamp will glow with a pre-flash brilliance governed by the resistor 58 because the silicon controlled rectifier 55 will be triggered in the same way as is the silicon controlled rectifier 34 of FIG. 8 during the pre-flash period. A closing of the triggering switch 62 in FIG. 9 will cause a gate current governed by the resistor 57 to reach the silicon controlled rectifer 55. Once the silicon controlled rectifier 55 is rendered conductive under these circumstances, the lamp 43 will have the full line voltage (minus the voltage drop over the rectifier 55) across its terminals.

FIG. illustrates an exemplary circuit diagram for the flash apparatus of the present invention, wherein a timing circuit is used to remove power from the lamp as quickly as possible.

In this embodiment a lamp 63 is connected by means of

leads

64 and 65 to a source of current (generally indicated at 66) which, again, may be ordinary house current. The lead 64 contains a normally open switch 67. When the lamp 63 is connected to a source of power, as at 66, current will by-pass the normally open switch 67 by means of lead 68 containing a rectifier 69. The lead 68 may also contain a resistor 70 in series with the rectifier 69 to provide a further reduction of lamp voltage during the standby or pre-flash period. The circuit thus far described is similar to that described in connection with either FIGS. 2 or 3 (depending upon the presence of a resistor in series with the rectifier). The normally open switch 67 comprises one of two switches forming a part of a relay 71. The relay 71 is connected through normally open triggering switch 72 to a capacitor 73. The capacitor 73, in turn, is charged through

resistors

74 and 75. Resistors "m and 75 serve to isolate the operator from the power line circuitry and should have a sufficiently high voltage rating to prevent arc-through. The capacitor 73 is capable of furnishing a measured power pulse sufficient to close the relay 7t (thus closing switch 67) and sustain the relay in closed position for a period of time of sufficient duration to cause the lamp 63 to flash at full brilliance while the camera shutter is open and the film is exposed. The relay 71 then immediately reopens and cannot be closed again until the capacitor 73 is recharged.

The resistor 74 is connected to a lead 76 which, in turn, is connected across the

leads

64 and 65. The lead 76 contains a rectifier 77 and a capacitor 78. This rectifier-capacitor combination yields a direct current potential equal to the peak of the AC line voltage. The sole function of this circuit is to provide a direct current source from which the capacitor 73 is charged. When the capacitor 73 is in charged condition, a closing of the trigger switch 72 will enable the measured power pulse from the capacitor to actuate relay 71 and thus switch 67 causing the lamp 63 to receive full line voltage. If, however, during the operation of this embodiment the switch 72 were closed for only an extremely short period of time so that the relay was furnished with power for only such short period of time, the timing function of this embodiment would be lost. This, however, is prevented by the provision of the circuit containing switch 79. Switch 79 comprises a part of relay 7H and has its contacts so spaced that the slightest motion of the relay armature will cause normally open switch 79 to close. Switch 79 will remain closed until such time as capacitor 73 is discharged. Thus, the timing circuit of the embodiment of FIG. 10 is substantially independent of the duration of time for which switch 72 is depressed.

The embodiment of FIG. 10 is particularly suited to be located in a photoflash housing comprising an integral or separable part of a camera. The lead 64 may contain a switch 80. The switch 80 may be of any suitable type, such as a push button switch or the like. The switch 80 may be included so that lamp power may be applied just prior to the operation of the camera. Thus, the unit may be connected to a source of electricity, as at 66, but will not function until the switch 80 is closed.

As illustrated, the lead 64 may also include a thermostatic switch 81. The thermostatic switch 81 may be provided so that internal temperatures of the flash unit may be prevented from rising beyond a safe limit for the type of material from which the photoflash housing is manufactured. In this way, damage to the photoflash unit or the camera from an overheating of the flash unit may be prevented.

In all of the embodiments of FIGS. 1-10, circuit protection may be furnished by fuse means or circuit breaker means, as is usual with devices of this power demand.

In the use of incandescent bulbs of the type described, it is necessary that they be turned off after a definite short period of time since, at maximum full brilliancy, the filaments are near failure and are incapable of maintaining full brilliancy for a sustained period of time. One method of preventing filament failure is to provide a timing circuit as illustrated in FIG. 10. Other suitable means may be applied to the embodiments shown in FIGS. 1-9. For example, these embodiments may be provided with circuit breaker means of well known types, having contacts suited to such use, and provided with actuating means which causes the lamp circuit to be interrupted after a short period of time. Such 'a short period of time may typically range from one to four seconds, depending upon the nature of the incandescent lamp or lamps being used. In this way, the lamps will be shut off after an appropriate period of time, irrespective of the length of time for which the triggering switch is held in closed position. Should the circuit breaker open, it must be reset before the flash apparatus may be used again, as is common with approved devices of this sort. For purposes of an exemplary showing circuit breakers of the type described are shown at 81a in FIGS. 6-9.

It is within the scope of the present invention to have the flash apparatus thereof built into or constitute an integral part of a camera itself. In such an instance, the triggering switch of the flash apparatus should be actuated simultaneously with the camera shutter lever, bar or push button. This may be accomplished by any well known electrical or mechanical means.

In many instances it is desirable to have the triggering switch actuated remotely by means controlled by the operator. For example, this is particularly true in-instances where the trigger switch carries all of the current, as in the embodiments of FIGS. 1-3. Such trigger switch actuating means may be controlled, for example, by the hand or foot of the operator.

FIGS. 11-16 illustrate an exemplary means whereby the triggering switch may be remotely actuated. These means comprise hydraulic, pneumatic or electrical actuators which are located on that finger of the operator which is used to depress the camera shutter lever, bar or push button. An additional advantage of these devices lies in the fact that the flash apparatus of the present invention may be used with any camera without requiring special adaptation of the camera to its use.

One form of remote trigger switch actuator is illustrated in FIGS. 11 and 12. The trigger switch actuator is generally indicated at 82 and comprises a hollow,

bulb 83 and a ring-like member 84. The actuator 82 may be an integral molded member of any suitable flexible material such as vinyl, rubber, vinyl rubber, neoprene or silicone compounds.

The bulb portion 83 has an integrally molded neck 85 adapted to receive the end of an elongated, flexible, hollow tubular member 86. The tubular member 86 may be of any suitable and convenient length, and terminates in a second bulb (as will be described hereinafter). The juncture of the tubular member 86 and the bulb neck 85 should be both airtight and watertight. This may be accomplished either frictionally, or by any other suitable means such as heat sealing, bluing and the like.

FIG. 13 illustrates an exemplary form of triggering switch. In this embodiment, the switch comprises two strap-like metallic elements of U-shaped configuration. The downwardly depending end portions 870 and 88a of the

switch elements

87 and 88 terminate respectively in outwardly extending flanges 87b and 88b. These flanges may be affixed by any suitable means (such as rivets, glue or the like) to an insulative base generally indicated at 89. It will be understood that the insulative base and the switch elements may be located within a photoflash housing, a camera case or the like.

Wires

90 and 91, connecting the switch with the rest of the photoflash circuitry may be affixed to the switch elements (as shown) by any suitable means such as soldering or the like.

The contacting portions 870 and 880 of the

switch elements

87 and 88 are arranged at right angles to each other with portion 870 overlying and out of contact with portion 880. The portion 87c may be provided with a downwardly extending dimple 92.

As indicated above, the elongated tubular member 86 is provided at its other end with a second bulb. This second bulb is shown at 93 in FIG. 13. The bulb 93 may be made of the same material as the actuator 82 and has a neck portion 94 adapted to receive the end of the tubular member 96 in watertight and airtight fashion. The bulb 93 may be held in position by any suitable means (not shown). It is within the scope of the invention to make the bulb of such size as to fill the area between switch element portions 87a, 87b, 88a and 88b so that the bulb is held in place by the switch elements themselves.

The system comprising the actuator bulb 83, the bulb 93 and the elongated tubular member 86 may be filled with a fluid medium such as air, liquid or the like.

If the actuator 82 is applied to that finger of the operator which is used to depress the camera shutter lever, bar or push button, the depression of the camera shutter lever will simultaneously cause the squeezing or collapsing of the actuator bulb 83. For purposes of an exemplary showing, the bulb 83 in FIG. 12 is shown in position against a camera shutter lever 95. The sqeezing or collapsing of the bulb 83 will cause the liquid or gaseous medium in the line 86 to flow toward the bulb 93. The bulb 93 will tend to expand. Since the bulb 93 is located between the contact portion 88c of the switch element 88 and the base 89, expansion of the bulb 93 will cause the switch portion 880 to move upwardly into contact with the switch portion 87c thereby closing the triggering switch. The dimple 92 in the switch portion 87c will insure a good contact between switch portions 870 and 880.

FIG. 14 illustrates another form of triggering switch actuable by the bulb 93. In this instance two L-shaped flexible, metallic contacts 96 and 97 are affixed in spaced relationship to an insulative base 98 by any suitable means such as

rivets

99 and 100. Wires 101 and 102 are affixed by soldering or the like to the base portions of the switch elements 96 and 97 and connect these elements with the remainder of the flash apparatus circuitry. A U-shaped switch contact element 103 is located between the switch elements 96 and 97 and is affixed to the insulative base by suitable means such as rivet 104. The upstanding portions of the switch element 103 are located near and in spaced relationship to the upstanding portions of the switch elements 96 and 97. The bulb 93 is held (by suitable means not shown) between the upstanding portions of the switch element 103.

Depression of the camera shutter lever, and consequent squeezing of the actuator bulb 83, as described above with respect to FIG. 12, will cause expansion of the bulb 93. Expansion of the bulb 93 will cause the upstanding portions of switch element 103 to come into contact with the upstanding portions of switch elements 96 and 97, thereby closing the triggering switch of FIG. 14.

It will be understood by one skilled in the art that as soon as the pressure applied to the actuator bulb 83 is released, the bulb 93 will contract to its normal shape and the switches of FIGS. 13 and 14 will be caused to open.

FIGS. 15 and 16 illustrate another embodiment of the remote actuator for a triggering switch. In this instance, the actuator comprises an electrical switch which, when closed, will actuate any suitable form of triggering switch such as a relay or the like.

It will be noted from FIG. 16 that this embodiment of the remote triggering switch actuator is similar in appearance to the embodiment of FIG. 11. The actuator comprises a bulb 105 and a ring-like portion 106. The bulb and ring-like portions may be integral and may be molded of the same materials outlined with respect to the embodiment of FIG. 11. In this instance, however, the bulb portion 105 contains a small pair of spaced contacts, adapted to come together and complete the circuit when the bulb 105 is used to depress the camera shutter lever, bar or push button.

The individual switch elements are most clearly shown in the exploded view of FIG. 15. A piece of insulative material, generally indicated at 107, has a peripheral configuration similar to the figure 8 and is folded in half along the fold line 108 to form two substantially circular opposed halves 107a and 10711. The insulative member 107 may be made of any suitable material such as Mylar or the like. The member 107 is provided with a slot 109 located centrally of the fold line 108. a

A pair of contacts are shown at 110 and 111. The

contacts

110 and 111 may be substantially circular in 2 configuration, each having narrow

rearward extensions

110a and 111a respectively. The

extensions

110a and 111a are adapted to pass through the slot 109 in the member 107. Wires or leads 112 and 113 are attached (as by soldering, welding or the like) to the extensions 1 a and 1 1 1a respectively, the leads 1 I2 and 113 constituting a part of the triggering switch circuitry.

The contact extensions 110a and 1110 may be coated with an insulating resin, or they may be prevented from short-circuiting by the use of a thin T-shaped member of insulative material such as Mylar or the like. The T- shaped member is illustrated at 114. The portion 114a of the T-shaped member is adapted to extend through the slot 109 in the member 107 and to lie between the

contact extensions

110a and 111a. The portion lI4b of the T-shaped member serves not only to properly locate the T-shaped member but also as a fulcrum for the

contacts

110 and 111.

The

contacts

110 and 111 may be made of metal or metallized conducting surfaces on a substrate of insulating material. In assembly (as shown in FIG. 16) the

contacts

110 and 111 oppose each other and are affixed to the portions 107a and 107b respectively of the insulative element 107 by any suitable means such as glue, adhesive or the like.

Depending upon the materials from which it is made, the bulb 105 may be molded about the various switch elements, or it may be premolded and then slit as at 105a. The switch elements and leads may be introduced into and positioned within the bulb via the slit 105a which is then sealed by fusing, cementing or the like. It will be noted from FIG. 16 that the

contact extensions

110a and 111a, the portion 114a of the T- shaped member and the leads are located in an integral neck portion 115 of the bulb 105. To insure that the leads 1 l2 and 113 do not inadvertently become disconnected from the contact extensions, they may be fused, cemented or otherwise mechanically fastened within the neck 115. It will be understood by one skilled in the art that the leads 112 and 1113 (as is true of the flexible tubular member 86 in FIG. 11) may be of any convenient length depending upon the desired placement of the flash apparatus.

The remote trigger switch actuator of FIG. 16 is used in precisely the same manner as described with respect to the embodiment illustrated in FIG. 12. When the bulb portion 105 is used to depress the camera shutter lever, bar or push button, the contacts 1 10 and 111 will be closed completing the triggering circuit. To insure good contact between the

elements

110 and 11 1 one of them may be provided with a dimple. Such a contacting dimple is illustrated at 110b in FIGS. 15 and 16.

As indicated above, the various embodiments of the flash apparatus of the present invention may be mounted in any suitable type of housing. The housing itself does not constitute a part of this invention. For example, the housing may be an integral portion of a camera case, or it may constitute a completely selfcontained unit adapted to be attached to a camera case or to be hand held. The one or more incandescent lamps constituting a part of the flash apparatus of the present invention may be located within the flash apparatus housing, or they may be separate therefrom and connected thereto by suitably insulated wires. In the latter instance, for example, the lamps themselves may be suitably mounted in appropriate reflectors and supported in tripods or the like, in the same manner as is typical with ordinary photofloods.

In accordance with the teachings of the present invention, the provision of means for illuminating an incandescent lamp or lamps to an initial pre-flash level with the subsequent flashing of the lamps to full brilliance substantially simultaneously with the opening of the shutter, not only adds to the life of the incandescent lamp, but enables the use of incandescent lamps characterized by a shorter filament life and a greater peak brilliance.

In all of the embodiments described above, for a particular bulb or for a particular set of circumstances, it is well within the skill of one knowledgeable in the art to determine and utilize circuit elements of the proper rating. For example, in the circuit of FIG. 7, when

lamps

14 and 15 were selected such that they would reach peak brilliance at 120 volts, it was found that a resistor rated at 12 or 13 ohms would serve adequately as the resistor 29.

In the embodiment shown in FIG. 10 excellent results were achieved when the lamp 63 was chosen such as to reach maximum brilliance at 120 volts. Under such circumstances, a 6 to 12 ohm resistor may be used at 70, and a 220,000 ohm resistor may be used at 74 and 75. A relay of 5,000 ohms resistance was used successfully together with a six microfarad capacitor (at 73) capable of withstanding peak line voltage. A 0.02 microfarad capacitor capable of withstanding peak line voltage was used at 78.

FIG. 17 is an electrical diagram substantially identical to that of FIG. 10 and like parts have been given like index numerals. FIG. 17 illustrates the circuit of FIG. 10 without the pre-flash illumination feature. This is accomplished simply by eliminating from the circuit of FIG. 10 the switch 80, the lead 68 and its

elements

69 and 70. In all other respects, the operation of the circuit of FIG. 17 is identical to that described with respect to FIG. 10.

In the circuit of FIG. 17 the lamp 63 may be an ordinary photoflood. Such a lamp is particularly adapted to withstand the sudden application of power. It will be noted that the thermostatic switch 81 of FIG. 10 is not present in FIG. 17. In general, such a switch is not required because the circuit of FIG. 17 does not contain the pre-flash resistor 70 (of FIG. 10) which would have a tendency to give off heat. In addition, the lamp 63 will be illuminated for a very short time. It would be within the scope of the invention to include a fuse or curcuit breaker in the circuit of FIG. 17. However, in general these devices are also not necessary because, if the relay is properly designed, the ordinary house fuse will take care of any overcurrent.

When lamp 63 of FIG. 17 comprises a photoflood, it would be preferable to arrange the trigger switch 72 in such a way as to be closed immediately prior to actuation of the camera shutter switch. This would enable the photoflood to reach full brilliance. As a consequence, the embodiment of FIG. 17 is an ideal situation for the use of the trigger switch mechanisms of FIGS.

11 through 16.

FIG. 18 is similar to FIG. 17 and like parts have been given like index numerals. FIG. 18, however, illustrate a modified form of the timing circuit.

It will be understood that the like parts of FIGS. 17 and 18 serve the same functions. In FIG. 18, however, a silicon controlled rectifier 116 in series with the relay 71 has been substituted for relay switch 79 (FIG. 17). The normally open triggering switch 72 is connected to the gate of the silicon controled rectifier 116. A resistor 177 is in series with the triggering switch 72 so as to furnish proper current. Finally, a desensitizing resistor 1 18 may be provided, as is well known in the art.

As in the case of FIGS. and 17, the capacitor 73 is charged through

resistors

74 and 75, which also serve to isolate the operator from the power line circuitry. The capacitor 73 will be so chosen as to be capable of furnishing a measured power pulse sufficient to close relay 71 and sustain the relay in closed position for a period of time of sufficient duration to cause the lamp 63 to flash at full brilliance while the camera shutter is open and the film is exposed. The capacitor 73 will actuate the relay 71 in this manner once the triggering switch 72 is closed and gate current is applied to the silicon controlled rectifier 116. Thereafter, irrespective of whether or not the triggering switch 72 is closed, the silicon controlled rectifier 116 will permit current flow to the relay 71 until such time as the charge in the capacitor 73 is depleted below the holding current value of the silicon controlled rectifier.

FIG. 19 illustrates a circuit diagram similar to FIG. 18 (like parts having been given like index numerals) with another modification of the timing circuit. Those elements having been given like index numerals in FIGS. 18 and 19 serve the same purposes.

In this embodiment, the gate of the silicon controlled rectifier 116 is connected to the lead 65 through a capacitor 119 and a resistor 120. The normally opened triggering switch 72 is connected from this last mentioned lead to that lead containing the capacitor 73, the silicon controlled rectifier 116 and the relay 71. Again, the capacitor 73 is charged through

resistors

74 and 75. In this embodiment the operator is isolated from the power line circuitry by resistor 120, as well as

resistors

74 and 75. Finally, a lead 121 is provided, having resistors 122 and 123 therein. The resistors 122 and 123 are voltage divider resistors, as is well known in the art, and determine the proportion of the available voltage to be allotted capacitor 73 and capacitor 119. The resistor 120, in addition to its function as one of the means to isolate the operator from the power line circuitry, also serves to limit the charging current to the capacitor 1 19 through resistor 118 to a value such that the gate of the silicon controlled rectifier 116 will not be actuated.

The operation of the circuit of FIG. 19 may be described as follows. The capacitor 73 is charged through

resistors

74 and 75. The capacitor 119 is charged through resistor 120. As indicated above, the available voltage to be allotted to

capacitors

73 and 119 is regulated by the voltage divider resistors 122 and 123. When the normally open triggering switch 72 is closed, capacitor 119 discharges into the gate of silicon controlled rectifier 116 causing it to conduct, This in turn, actuates relay 71 resulting in the closure of switch 67. Relay 71 will continue to be actuated until the charge on capacitor 73 is depleted below the holding current of silicon controlled rectifier 116. At this time, capacitor 73 is substantially discharged. When the silicon controlled rectifier 116 ceases conduction, capacitors 73 and 1 19 will recharge. Thus, it will be apparent that a timing circuit has been provided, which circuit is independent of the duration for which the normally open triggering switch 72 is closed.

The timing circuit of FIG. 19 has the advantage over that of FIG. 18 in that one terminal of the normally open triggering switch is common to the ground return of the silicon controlled rectifier 116. This provides further freedom from false operation of the silicon controlled rectifier due to static impluses or the like.

In an exemplary embodiment of the circuit of FIG. 19, the resistor 122 may have a value of 220,000 ohms. The resistor 123 may have a value of 110,000 ohms. Capacitor 78 may have a value of 0.1 mfd. Resistor may have a value of l megohm. resistor 118 may have a value of 1,000 ohms. The value of capacitor 119 will be determined by the type of silicon controlled rectifier 116 used. Generally, this value may range from 0.2 to 20 mfd. It will be understood by one skilled in the art that these values are exemplary, and are not intended to be limiting since other values may be used.

In the circuits of FIGS. 17 through 19 an ordinary photofiood may be used as the lamp 63. The timing circuits of these Figures will increase the life of the photoflood lamp. In addition, the subject being photographed will be far more comfortable than he would be when photofloods are used in a conventional manner.

It will be understood by one skilled in the art that the embodiments of FIGS. 18 and 19 may be provided with pre-flash illumination means in the same manner described with respect to FIGS. 10. In such an instance, the lamp 63 should be properly choosen for maximum efficiency, as described with respect to FIG. 10.

Although the various embodiments of the present invention have been described with respect to the use of filament type lamps, it is within the scope of the invention to utilize gaseous arc lamps. In addition to the various advantages described above with respect to the filament type lamps, including pre-photograph illumination and the like, the use of gaseous arc lamps in the embodiments described will make possible a greater illumination efficiency.

In operation, the arc of the lamp may be maintained by known means including ballast means, and full power is applied by the means taught herein. Modifications of the exemplary circuits for gaseous arc lamp use will be apparent to those skilled in the art.

FIG. 20 is a diagrammatic illustration of a circuit of the present invention utilizing a gaseous arc lamp in combination with a timing circuit similar to that of FIG. 10. In this instance, a gaseous arc lamp 124 is connected by a pair of

leads

125 and 126 to a source of current (generally indicated at 127). As in the case of the embodiment of FIG. 10, the source of current 127 may be ordinary house current. The lead 126 contains a resistor 128 which serves not only to nullify any wiring resistance differences encountered when the circuit is connected to different sources of house current, but also serves to prevent overcurrent to the lamp 124. The line 126 further may contain a protective device 129 which may take the form of a fuse, circuit breaker or the like. If, for any reason the timing circuit of FIG. 20 should fail, or if for any other reason the gaseous arc lamp 124 should fail to turn off, the device 129 will not only protect the flash unit itself, but also the house fuses, or the like, which protect the current of the source 127.

Lead 130 is connected across leads 125 and 126 and contains a diode rectifier 131 and capacitor 132, which combination comprises a half-wave rectifier yielding a direct current potentially equal to the peak of the AC line voltage. A lead 133 is connected to lead 130 through a resistor 134. A lead 135 is connected to lead 125 through a resistor 136.. Lead 135 also contains a switch 137 which may be described as the trigger switch. The switch 137 may be actuated remotely, by any of the previously described means, or it may be in association with the camera shutter switch.

Across leads 133 and 135 there extends

leads

138 and 139. Lead 138 contains a capacitor 140. Lead 139 contains a capacitor 141. Finally, leads 133 and 135 are connected to an interrupter generally indicated at 142. The interrupter may be of any suitable type for generating an ignition potential between a trigger electrode 143 for the lamp 124 and one of the lamp electrodes, sufficient to ignite the arc of the lamp.

in an exemplary form, the interrupter 142 may be of the vacuum enclosed switch type. Owing to the very fast breaking characteristics of such a switch, a very high voltage is produced when the switch is used to make and break current through an inductive device. An exemplary, though non-limiting, form of inductive device may comprise a drive coil 142a, the inductance of which serves the above purpose.

While not so limited, the interrupter switch may be of single reed construction. This reed 14l2b is magnetically biased (as at 1420 and 142d) to have good sensitivity to the magnetic field provided by the surrounding coil 1420.

The interrupting frequency is preferably much higher than the line frequency, so as to insure operation of the lamp 124 at the earliest possible moment after triggering switch 137 is closed. While the interrupting frequency does not constitute a limitation on the present invention, a frequency of 300 cycles per second has given excellent results. The duration of illumination of the lamp 124 may extend over more than one-half of a power cycle. Reignition of the lamp 124 occurs so long as sufficient interrupter output voltage is available.

While an exemplary form of interrupter has been described, as indicated above it may take other forms. For example, gas filled enclosed contacts or contacts in open air or oil may be used instead of vacuum switching contacts. In addition, a single interrupting reed is not required. Standard reed switches may be used if associated with proper drive means such as magnetic bias and a series connected inductive element. The latter may be a drive coil or an indepenent inductive means.

It will further be understood by one skilled in the art that means other than an interrupter may be used to produce thee high voltage for triggering the lamp 124. Such means include spark gap-induction coil means or solid state means employing switching transistors and other types of solid state components. Another possible source of arc ignition voltage might be certain types of piezoelectric devices. Such devices can be used to initiate the operation of a symmetrically emissive arc flash lamp. Under these circumstances, the lamp would have to be turned off by means of a circuit breaker, solid state interrupting means or a fuse or fusing material.

The lamp 124 may also take various forms. In an exemplary embodiment, the lamp may comprise two electrodes of different structure located at opposite ends of a transparent enclosure. To assist in turning off the arc in the absence of trigger voltage, the electrodes may be dissimilar. in an exemplary, but non limiting example, one electrode may be of the cold cathode type coated with electron emissive material while the other electrode may be of the cold cathode type and made of molybdenum, tantalum, tungsten or other material in uncoated condition. The un-coated electrode tends to be less electron emissive than the coated one, when unheated.

Further means may be employed to assure that the arc turns off. For example, variations in electrode mass may be used to enhance turn-off characteristics. In such an instance, the larger electrode tends (for a given amount of heat) to reach a lower temperature than the first electrode, which may be coated coiled tungsten, or the like. The term coiled" is used in a non-limiting sense and is intended to encompass coiled, coiled-coil, or a further coiled configuration.

It is also within the scope of the invention to provide the first electrode in a solid, tubular, or other configuration to enhance its cold cathode characteristics, all as is common in the art.

Finally, both electrodes may be coated or un-coated if suitable circuit design precautions are observed.

The operation of the circuit of FIG. 20 may be described as follows. When the circuit is connected to the source of current 127 a low voltage line current will be applied to the lamp 124 via

leads

125 and 126. This current is sufficient to illuminate the lamp if the gas in the lamp is ionized. This current is controlled by the resistor 128.

At the same time, capacitor is charged through

resistors

134 and 136. The values of the

resistors

134 and 136 should be chosen to give a desired charging current for capacitor 140.

Resistances

134 and 136 also serve to protect the operator against accidental harmful contact with ground through the camera. The values of

resistances

134 and 136 and the size and capacity of capacitor 140 will also determine the time required to charge capacitor 140.

Upon closure of trigger switch 137, there will be a transfer of charge from capacitor 140 to capacitor 141. Again, it will be understood by one skilled in the art that the choice of size and capacity of capacitors 140 and 141 will depend upon the desired final results sought to be achieved. While this choice does not constitute a limitation on the invention, it is preferable to have capacitor 140 be of low capacity and high voltage, while capacitor 141 should be of high capacity and lower voltage. In this way, the preponderance of charge of capacitor 140 will be transferred to capacitor 141 substantially simultaneously with the closing of trigger switch 137. Thus, the function of the circuit will not be dependent upon hold-down time of trigger switch 137.

Once charged, capacitor 141 will serve as a source of direct current which will be transformed into a pulsating high voltage current by interrupter 142. This high voltage will be transmitted by lead 144 to trigger electrode 143 of lamp 124. With the trigger electrode 143 energized, the gas within the gaseous arc lamp 124 will be ionized and the line current will cause the lamp 124 to illuminate. Lamp 124 will be illuminated until the charge on capacitor 141 has dissipated below the value required to energize the trigger electrode 143. Thereafter, lamp 124 will turn off.

It will be understood by one skilled in the art that trigger electrode 143 may comprise a wire or may be a painted electrode of known type. It will further be understood that in the absence of capacitor 141, the duration of illumination of gaseous arc lamp 124 would depend upon the duration of closure of trigger switch 137. In the circuit of FIG. 20, however, even if trigger switch 137 were held closed, there would be insufficient current through

resistors

134 and 136 to keep capacitor 141 charged, so long as

resistors

134 and 136 and capacitors 140 and 141 were properly chosen with respect to their electrical properties.

A timer circuit of FIG. serves not only to render operation of the circuit substantially independent of the time for which trigger switch 137 is closed, but also to control the total power applied to lamp 124. The trigger circuit ensures that gaseous arc lamp 124 will not glow so long as to be damaged or as to get so hot that it will not turn off.

When desired, the circuit of FIG. 20 may contain a return capacitance, shown in dotted lines and generally indicated by index numeral 145. Under normal circumstances, the normal wiring capacitance will be found sufficient and return capacitance 145 will not be needed.

FIG. 21 is similar to FIG. 20, and like parts have been given like index numerals. FIG. 21 illustrates a circuit wherein the interrupter 142 is controlled by a timing circuit of the type described with respect to FIG. 18. Thus, resistor 146 corresponds to resistor 117 of FIG. 18. Similarly, the silicon controlled rectifier 147 and the resistor 148 corresponds to

elements

116 and 118, respectively, in FIG. 18. Finally, a capacitor 149 is con nected across the silicon controlled rectifier 147 to protect it, as is well known in the art.

The operation of the triggering circuit of FIG. 21 is substantially identical to that of FIG. 18. The primary difference lies in the fact that the triggering circuit of FIG. 21 drives the interrupter 142, rather than a relay such as the relay 71 in FIG. 18. Again, the capacitor 140 is charged through

resistors

134 and 136 which also serve to protect the operator. Upon closure of the normally opened triggering switch 137, gate current (regulated by resistor 146) is applied to the silicon controlled rectifier 147 which is rendered conductive. As a consequence, the interrupter 142 will be operated until the charge on the capacitor is depleted below the value of the holding current required by the silicon controlled rectifier 147.

FIG. 22 is similar to FIG. 20, and again like parts have been given like index numerals. In this instance, the triggering circuit taught with respect to FIG. 19 has been combined with the circuit of FIG. 20. As a consequence,

voltage divider resistors

150 and 151 are equivalent to resistors 122 and 123 of FIG. 19. Similarly, resistors 152 and 153 are equivalent to

resistors

120 and 118, respectively, in FIG. 19. The capacitor 154 and the silicon controlled rectifier 155 are the counterparts of capacitor 119 and silicon controlled rectifier 116 in FIG. 19. Finally, a capacitor 156 is connected across the silicon controlled rectifier 155 to protect it, as in the case of capacitor 149 in FIG. 21. The operation of lamp 124 by interrupter 142 is identical to that described with respect to FIG. 20. The operation of the interrupter 142 by the timing circuit elements is identical to that described with respect to the operation of the relay 71 in FIG. 19.

FIG. 23 illustrates yet another embodiment of the flash apparatus of the present invention. The embodiment comprises an arc lamp 157 similar to the arc lamps 124 of FIGS. 20 through 22. The lamp is connected by

leads

158 and 159 to a source of electrical current 160. The source 160 may, for example, be ordinary house current. In the lead 158 there is a resistor 161 which serves the identical purpose described with respect to the resistor 128 in FIG. 20. The circuit may also be provided with a fuse or circuit breaker 162.

Generally a 10 amp fuse will be found satisfactory for this purpose.

The circuit of FIG. 23 incorporates a timing circuit identical to that described with respect to FIG. 10. Thus, the diode 163 and capacitor 164 serve the same function as diode 77 and capacitor 78 of FIG. 10.

Resistors

165 and 166 are similar to

resistors

174 and 175 of FIG. 10. The capacitor 167, relay 168 and locking switch 169 are substantially identical to the capacitor 73, relay 7] and locking switch 79 of FIG. 10. A normally open triggering switch is illustrated at 170.

In this embodiment a lead 171 extends between

lead

158 and 159. The lead 171 contains a switch 172, a fuse 173 and the primary 174a of a transformer generally indicated at 174. The fuse 173, for purposes of an exemplary showing, may be considered a live amp fuse serving to protect the primary 174a of transformer 174. The primary can sustain operations for only a few seconds without burn out, when actuation of the triggering switch causes closing of the switch 172 via the relay 168.

When switch 172 is closed, the timed (60 cycle) pulse appears across the transformer primary 174a. The transformer secondary 174b is so configured as to have an output of approximately 2,000 volts. This output is exemplary, since greater or lesser voltages may be used. A capacitor 175 is series connected with the primary 176a of a radio frequency transformer generally indicated at 176. Again, for purposes of an exemplary showing, the transformer 176 may be of 2.5 mh. secondary inductance.

It will be evident to one skilled in the art that the combination of the capacitor 175 and the transformer primary 176a receives current from the transformer secondary 174b. A spark gap is provided, as at 177. When switch 172 is closed at some point near the maximum voltage of transformer 174, spark gap 177 breaks down, thereby causing a short circuit across transformer 174 and discharging capacitor 175 through the are. This, in turn, causes a large voltage to appear across the secondary 176b of transformer 176. The secondary 176b is connected by lead 178 to the trigger electrode 179 of the lamp 157. Again it will be understood that the trigger electrode 179 of lamp 157 may be the same as the trigger electrode 143 described with respect to FIG. 20.

Thus, when the normally open triggering switch 170 is closed, the timing circuit will operate in the manner described with respect to FIG. 10. This, in turn, will cause switch 172 to close and the lamp 157 will be illuminated in the manner just described. Since the transformer 174 produces spark gap break down on both halves of the alternating circuit cycle, a pulsating radio frequency trigger voltage is produced at l/l20 second intervals. When used with a suitable lamp 157, the operation of the timing circuit assures turn off.

The circuit of FIG. 23 is best adapted for use with cameras set for rather long exposure times, as it may be late in flashing by as much as l/ 120 second. Longer exposure time adjustments will produce smaller variations in light exposure. The embodiment of FIG. 23 has a greater delay in starting (1 [120 of a second) than do the embodiments of FIGS. through 22, which exhibit a delay of about 1/300 of a second.

FIG. 24 is similar to FIG. 23 and like parts have been given like index numerals. The electrical diagram of FIG. 24 differs from that of FIG. 23 in that it incorporates a timing circuit of the type taught with respect to FIG. 18. Thus, the locking switch 169 of FIG. 23 has been eliminated.

Resistors

180 and 181 and silicon controlled rectifier 182 correspond to resistors 117 and ll 18 and silicon controlled rectifier I 16, respectively, of FIG. 18. The timing circuit of FIG. 24 operates in the manner described with respect to FIG. 18. When the relay 168 closes the switch 172, the lamp 157 is illuminated in the manner described with respect to FIG. 23.

FIG. is again similar to FIG. 23 and like parts have been given like index numerals. FIG. 25 illustrates the application of a timing circuit of the type taught in FIG. 19 to the circuit of FIG. 23. As a consequence, voltage divider resistors 183 and 184 correspond to the resistors I22 and 123 of FIG. 19. Similarly,

resistors

185 and 186 correspond to

resistors

120 and 118 respectively, of FIG. 19. The silicon controlled rectifier 187 and the capacitor 188 correspond to the like parts 116 and 1 19 of FIG. 19. The timing circuit of FIG. 25 works in a manner identical to that described with respect to FIG. 19. When the timing circuit, upon closure of normally open triggering switch 170 causes actuation of the relay 168, this will result in a closure of switch 172. As a consequence, the lamp 157 will flash in the manner described with respect to FIG. 23.

Modifications may be made in the invention without departing from the spirit of it.

We claim:

1. Flash apparatus for use with photographic equipment and the like, which comprises a circuit containing a gaseous arc lamp and a protective current limiting device connected in series across a source of alternating current, triggering means in said circuit which when actuated causes the passage of current from said alternating current source through said lamp to illuminate said lamp, a timing circuit, said timing circuit comprising a primary energy storage capacitor, a source of high voltage to actuate said triggering means and a normally open triggering switch whereby closure of said triggering switch will cause actuation of said source of high voltage by a measured pulse from said primary energy storage capacitor resulting in the actuation of said triggering means and illumination of said lamp every half cycle of said alternating current and means for maintaining said source of high voltage in actuated condition until said primary energy storage capacitor pulse is substantially discharged.

2. The structure claimed in claim I including at least a pair of resistors isolating said timing circuit from said alternating current source, whereby to protect the operator of said photographic equipment from dangerous shock.

3. The structure claimed in claim 1 including a source of direct current, a pair of resistors being connected across said source of direct current and comprising a voltage divider system, said primary energy storage capacitor being connected to said voltage divider system via a pair of isolating resistors and in such a way as to receive the larger portion of the voltage available from said voltage divider system, said means for maintaining said source of high voltage in actuated condition comprising a silicon controlled rectifier in series with said source of high voltage and with its cathode connected to the negative terminal of said primary energy storage capacitor, the gate of said silicon controlled rectifier being connected through a triggering capacitor and a resistor in series to the negative terminal of said voltage divider system, a resistor shunting the gate to said cathode of said silicon controlled rectifier whereby to stabilize the triggering characteristics of said silicon controlled rectifier and to provide a return path for the charging current of said triggering capacitor, a protective capacitor in parallel with said silicon controlled rectifier, said triggering switch being connected between the negative terminal of said triggering capacitor and the cathode of said silicon controlled rectifier whereby said source of high voltage will be actuated until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

4. The structure claimed in claim 1 wherein said triggering means permitting said passage of current from said source of alternating current through said gaseous arc lamp to illuminate said lamp at full brilliance comprises a first relay contact switch, a high voltage step-up transformer, a spark gap, an excitation capacitor, a radio frequency transformer and a triggering electrode for said gaseous arc lamp, said first relay contact switch and the primary of said high voltage transformer being connected in series across said source of alternating current, the secondary of said high voltage transformer having at one end two leads, the first of said leads being connected to a spark gap, the second of said leads containing in series said excitation capacitor and the primary of said radio frequency transformer, the secondary of said radio frequency transformer being connected to said trigger electrode, a relay having an armature, said first relay contact switch being normally open and being movable to a closed position when said relay is actuated, said relay being connected to said primary energy storage capacitor through said triggering switch.

5. The structure claimed in claim 4 wherein said means for maintaining said relay in actuated condition comprises a second relay contact switch forming a part of said relay, said second relay contact switch being normally open and being movable to a closed position by the slightest movement of said armature when said relay is actuated, said relay also being connected to said primary energy storage capacitor through said second relay contact switch whereby said relay will be connected to said primary energy storage capacitor and said first and second relay contact switches will remain closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

6. The structure claimed in claim 4 wherein said means for maintaining said relay in actuated condition comprises a silicon controlled rectifier in series with said relay, the gate of said silicon controlled rectifier being connected to said primary energy storage capacitor through said triggering switch and a resistor in series whereby said relay will be actuated and said first relay contact switch will be closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

7. The structure claimed in claim 4 including a source of direct current, a pair of resistors being connected across said source of direct current and comprising a voltage divider system, said primary energy storage capacitor being connected to said voltage divider system via a pair of isolating resistors and in such a way as to receive the larger portion of the voltage available from said voltage divider system, said means for maintaining said relay in actuated condition comprising a silicon controlled rectifier in series with said relay and with its cathode connected to the negative terminal of said primary energy storage capacitor, the gate of said silicon controlled rectifier being connected through a triggering capacitor and a resistor in series to the negative terminal of said voltage divider system, a resistor shunting the gate to said cathode of said silicon controlled rectifier whereby to stabilize the triggering characteristics of said silicon controlled rectifier and to provide a return path for the charging current of said triggering capacitor, said triggering switch being connected between the negative terminal of said triggering capacitor and the cathode of said silicon controlled rectifier whereby said relay will be actuated and said first relay contact switch will be closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

8. The structure claimed in claim wherein said timing circuit is isolated from said main source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting said source of direct current from which said first capacitor is charged.

9. The structure claimed in claim 6 wherein said timing circuit is isolated from said source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting said source of direct current from which said first capacitor is charged.

10. The structure claimed in claim 1 wherein said source of high voltage comprises an interrupter switch and an inductive device, said interrupter switch adapted to make and break current through said inductive device.

11. The structure claimed in claim 10 wherein said interrupter switch comprises a single reed, vacuum enuum enclosed interrupter switch, said interrupter switch being magnetically biased whereby to have good sensitivity to the magnetic field provided by said surrounding coil.

12. The structure claimed in claim I wherein said means for maintaining said source of high voltage energized comprises a second capacitor connected in parallel with said primary energy storage capacitor and said source of high voltage, said triggering switch being connected between said primary energy storage capacitor and said second capacitor whereby said source of high voltage will be energized and said triggering means will be energized until said second capacitor is substantially discharged irrespective of the duration of time for which said triggering switch is closed.

13. The structure claimed in claim 12 wherein said timing circuit is isolated from said source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and third capacitor in series, said rectifier and third capacitor combination being connected through one of said resistors to said primary energy storage capacitor and constituting a source of direct current from which said primary energy storage capacitor is charged.

14. The structure claimed in claim 1 wherein said means for maintaining said source of high voltage in actuated condition comprises a silicon controlled rectifier in series with said source of high voltage, a protective capacitor in parallel with said silicon controlled rectifier, the gate of said silicon controlled rectifier being connected to said primary energy storage capacitor through said triggering switch and a resistor in series whereby said source of high voltage will be actuated until said primary energy storage capacitor is substantially discharged irrespective of the duration of time for which said triggering switch is closed.

15. The structure claimed in claim 14 wherein said timing circuit is isolated from said main source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting a source of direct current from which said primary energy storage capacitor is charged.

Claims

2. The structure claimed in claim 1 including at least a pair of resistors isolating said timing circuit from said alternating current source, whereby to protect the operator of said photographic equipment from dangerous shock.

8. The structure claimed in claim 5 wherein said timing circuit is isolated from said main source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting said source of direct current from which said first capacitor is charged.

11. The structure claimed in claim 10 wherein said interrupter switch comprises a single reed, vacuum enclosed switch, said inductive device comprising a coil, said vacuum enclosed interrupter switch being series connected with said coil, said coil surrounding said vacuum enclosed interrupter switch, said interrupter switch being magnetically biased whereby to have good sensitivity to the magnetic field provided by said surrounding coil.

12. The structure claimed in claim 1 wherein said means for maintaining said source of high voltage energized comprises a second capacitor connected in parallel with said primary energy storage capacitor and said source of high voltage, said triggering switch being connected between said primary energy storage capacitor and said second capacitor whereby said source of high voltage will be energized and said triggering means will be energized until said second capacitor is substantially discharged irrespective of the duration of time for which said triggering switch is closed.