CA1087433A

CA1087433A - Camera fixed time delay quench strobe

Info

Publication number: CA1087433A
Application number: CA275,601A
Authority: CA
Inventors: Bruce K. Johnson; George D. Whiteside
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1976-04-08
Filing date: 1977-04-05
Publication date: 1980-10-14
Also published as: GB1577757A; DE2715829C2; FR2347700B1; JPS52124332A; DE2715829A1; FR2347700A1

Abstract

Abstract of the Disclosure A photographic camera apparatus of the type having an automatic exposer control system for controlling a pair of scanning shutter blade elements, having respective primary aperatures therethrough for collectively defining a gradually varying effective aperture size as a function of the position of the blade elements together with corresponding photocell sweep secondary apertures therethrough for movement in corresponding with the primary apertures to define a small secondary effective aperture for admitting the passage of scene light to a photocell, is adapted for use with either an ordinary flashlamp or a quench strobe. The interchangeability between flash-lamp and quench strobe is made possible by utilizing the command signal to close the shutter blade elements from the camera exposure control system and thereafter providing a signal to the quench strobe to terminate the firing of its flash tube subsequent to the expiration of a time delay after the shutter blade closing command signal. The length of the time delay depends upon whether the camera is operating in an ordinary flash mode or in a "fill-in" flash mode in which there is a high intensity of ambient light. Correct exposure in both modes is easily obtained using the invention.

Description

3~3 55~0 BACKGROUND OF THE INVENTT~N
_ _ Field of the Invention This invention relates generally to an artificial illumination control ~system for photographic apparatus and more particularly, to an artificial illumination control system for use with either ordinary flash ~amps or other sources of artificial illumination such as a quench strobe.
Descri~tion of the Prior Art Eleetronic photographic strobe devices of the type :~
in which the flashlight produced by the flasn tube of the device is automatically terminated after a prede- :
termined quantity of light has been received from the scene being photographed by a light-respons~ve control portion of the device are well known in the art. Such strobes are commonly referred to as quench strobes. In addition to having an independent light-responsive control circuit in the strobe, it is also well known to utilize the exposure control circuit associated wi~h the aetual camera apparatus to control the firing and quenching of a strobe unit as is more fully disclosed in U.S. Patent 3,776,112, ~y ~ilwerding issued 1973. Wilwerding discloses a circuit coupled to the light-integrating exposure control circuit of a camera to effect the flash quenching of an electronic flash unit. Thus, it is well known :: .
to couple an eleetronically controlled shutter camera ; with a quenchable electronic strobe unit so tnat the strobe unit is quenched simultaneously with the command signal to return the shutter blade elements to their closed position.

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3,3 :., Such an arrangement however would not be compatible with an exposure control system o~ the type described in Canadian patent application Serial ~o.
262,~14 by Edwin ~. Shenk, filed September 30, 1976.
The aforementioned exposure control system is u~ilized in con~unction with a shutter blade arrangement o~ the so-called "scanning type" which embodies a pair of shutter blade elements, each o~ which includes a primary aperture therethrough to cooperatively define a gradually varying -~
ef~ective aperture size as a function o~ the position of the shutter blade elements. Each shutter blade element additionall~ includes a photocell sweep secondary aperture which apertures also cooperati~ely define a gradually varying e~fecti~e secondary aperture in ~ront o~ the exposure control photocell as a function o~
blade position. The photocell sweep secondary apertures are generally con~igured to progressi~ely open ahead of the primary apertures so that the exposure control circuit ef~ects the closing o~ the shutter blade elements at a ti~e prior to which the ~ilm i8 ..
~ully exposed. Prematurely signalling the shutter blade elements to close prior to the time required for a full -film exposure anticipates for the additional scene light which will impinge upon the film during the ~inite time , required for the shutter blade elements to fully close.
Thus, quenching the strobe solely as a function of the exposure control system command signal to initiate closing 1 of the shutter blade elements as disclosed in United States '` Patent 3,776,112, supr~ will result in an under-exposure since , .

, the strobe is quenched almost instantaneously. It is now proposed that the actual quench signal be delayed by a predetermined time delay which correl-ates to the anticipation characteristic of the photocell secondary apertures.
Such a time delay provides for satisfactory exposures in situations where the ambient scene light intensity is so low that the photographer would customarily utilize either a flashbulb or strobe. In situations where the ambient scene light intensity is high, and particularly, where the subject is framed against a lighted background, it may still be desirable to utilize a flashlamp or strobe in order to adequately expose the features of the subject. However, in such "fill-in" flash situations, the predetermined time dslay may result in overexposing the subject since the subject is already partially illuminated by the lighted background.
Accordingly it is also proposed that if the camera is utilized in a "fill-in" flash mode rather than an ordinary flash mode the time delay of the quenching signal be shortened depending on the intensity of the ambient light.
According to the present invention there i5 provided a photographic :::
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camera comprising a housing; means for electrical connection to a source of artificial illumination; a blade assembly arranged within the housing for displacement from an ini-tial closed arrangement wherein the blade assembly precludes scene light from impinging on an exposure plane to a : second arrangement wherein the blade assembly defines a maximum aperture for the passage of scene light and then to a final closed arrangement, :
such a displacement of the blade assembly serving to define an exposure interval; scene-light detecting means for providing an output signal in correspondence with the integrated amount of scene light detected subsequent ~ :
to the commencement of an exposure interval; and means for initiating the ~ .
displacement of the blade assembly from its initial closed arrangement to- :: .

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wards its second arrangement thereby commencing the exposure interval and for initiating the energizing of the source of artiEicial illumination to effect the firing thereof subsequent to the initiation of the exposure inter-val and then, responsive to the output signal of the scene-light detecting means reaching a predetermined value, for effecting the displacement of the blade assembly into its final closed arrangement and for initiating the de-energization of the source of artificial illumination to effect the termina-tion of the firing thereof subsequent to the expiration of a selected time delay commencing immediately after the output signal of the scene-light detecting means reaches the said predetermined value.
According to another aspect of the present invention, there is provided lighting apparatus for use with a photographic camera of the type . having means for providing at least two control signals in sequence during the course of a photographic interval, the lighting apparatus comprising: a source of artificial illumination; means for accommodating at least one electrical :.
connection from the lighting apparatus to the camera in order to facilitate the transmission of the two signals from the camera to the lighting apparatus means for coupling to a source of electrical energy; and means energizable by the source of electrical energyJ and responsive to the first of the two :.
. 20 signals from the camera for initiating the energization of the source of artificial illumination to effect the firing thereof; and then responsive to the second of the two signals from the camera for initiating the de-energization of the source of artificial illumination subsequent to the :
expiration of a predetermined time delay after receipt of the second of the two signals from the camera.
The invention will now be described in greater detail with refer-ence to the accompanying drawings in which Figure 1 is a perspective view of a photographic camera apparatus . ;~
emboyding an artificial illumination control system; .~ . .

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Fig. 2 is a front cross-sectional view of the camera of Fig. 1, showing a portion of a typical exposure control system;
Fig. 3 is a schematic diagram showing a portion of the artificial illumination control system of this invention;
Fig. 4 is a schematic diagram showing, in greater detail~ a portion of the artificial illumination control system of Fig. 3;
Fig. 5 is a schematic diagram showing the variable strobe time delay circuit of this invention;
Fig. 6 is a schematic diagram showing a quench strobe circuit; and Fig. 7 is a graphical representation of the control signals provided by the strobe time delay circuit o~ Pig. S.

7~3 Descri~tion of the Preferred F~b~diment Referring now to Figures 1 and 2, it can be seen that the artificial illumination control system of this invention ma~ be associated with a photographic camera Qp- -paratus 10 contained within a housing 11. A baseblock cast-ing 12 is fixedly stationed with the housing 11 and select-ively machined to support the various components of an exposure mechanism shown generally at 13. Surrounding the front and top of the baseblock casting 12, there is pro-vided a cover section 14 which includes at least one opening through which extends a manually ad~ustable focus bezel 22. Cen~rally disposed within the base-block casting 12, there is provided a light entering exposure opening 16 which defines the maximum available -exposure aperture for the system.
An objective or taking lens 18 is provided in - -overlying relation to the light entering opening 16 wherein the ob~ective lens 18 may comprise a plurality of elements retained in predetermined spaced relation by a cylindrical lens mount 20 which is externally threaded for toothed engagement within the internally threaded focus bezel 22. As is readily apparent, focus bezel 22 is made rotatable with respect to the front cover 14 to provide translational movement of the elements of lens 18 along the center axis 24 of the optical path of the housing 11.
As is readily apparent, the central optical axis 24 is ;
illustrated in ~igure 2 as being normal to the plane o~ the drawing. Thus, rotation of the ~ocus bezel 22 may be carried out by manual rotation to provide displacement of the elements of obJective lens 18 for ~ocusing of image . :

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carrying rays through the light entering exposure opening 16 to a real~ardly positioned film plane 26 by way of a reflecting mirror 28 all of which are s-tationed within a suitable light-tight film exposure chamber 30 within the housing 11.
Intermediate the ob~ective lens 18 and light entering exposure opening 16, there are supported two over-lapping shutter blade elements 32 and 34 which will be sub-sequently described in greater detail herein. Extending from the front cover 14 there is provided a photographic cycle initiating button Sl, the depression of which commences the exposure interval by ultimately e~fec-ting the release of the shutter blade elements 32 and 34. In addition, there is p:rovided a viewfinder shown generally at 25 which enables a photographer to properly fr~le the desired scene to be photographed.
A pair of scene light ad~itting primary apertures 36 and 38 are provided respecti~ely in the blade elements 32 and 3l~-to collectively define a progressive variation of effective aperture openings in accordance with simulta-neous longitudinal and lateral displacement of one blade element with respect to the other blade element in a manner as is fully described in a United States Patent Serial No.
3,942,183 entitled "Camera With Pivoting Blades" by George D. ~hitesiae,filed July 2, 1974, ana assigned in col~mon herewith. The apertures 36 and 38 are selectively shaped so as to overlap the light entering exposure open-ing 169 thexeb~ defining a gradually varying ef~ective aperture size as a function of the position of the blade elements 32 and 34.

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' Each of the blades, 32 and 34, may additionally be configured to have corresponding photocell sweep secondary apertures shown respectively at 40 and 42. Secondary apertures 40 and 42 may be configured in correspondence with the shapes of scene light admitting primary apertures 32 and 34. As is readily apparent, -the secondary apertures 40 and 42 also move in correspondence with the primary apertures 36 and 38 to define a small secondary effective aperture for admitting the passage of scene light trans-mitted through a second opening 43 in the cover 14 from the scene being photographed. Scene light admitted by the photocell secondary apertures 40 and 42 is thereafter directed to a light detecting station shown generally at 44. The light detectinq station includes a photore-sponsive element 46 which cooperates with light inte-grating and control circuitry as shown in Fig.3 to term-inate an exposure interval as a f~mction of the amount of light received through the secondary eff3ctive aperture defined by~the overlapping photocell sweep apertures 40 and 42.
Projecting from the baseblock casting 12 at a location spaced laterally apart ~rom the light entering exposure opening 16, is a pivot pin or stud 48 which pivotally and ;
translatively engages elongate slots 50 and ~2 formed in respective shutter blade elements 32 and 34. Pin 48 -:~
; may be integrally formed with the baseblock casting 12 and blade elements 32 and 34 may be retained in engaging relation with respect to the pin 48 by any suitable means such as peening over the outside end of pin 48.
The opposite ends of the blade elements 32 and 34 _9_ ~ . . . .
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7~33 respectively include extended portions ~-hich pivotally connect to a walking beam 54. Beam 54, in turn, is disposed for rotation relative to the baseblock casting 12 by pivotal connection to a projecting pivot pin or stud 56 which may be integrally formed with the base-block casting 12 at a location spaced laterally apart from the light entering exposure opening 1~. The walking beam 54 may be pivotally retained with re,pect to the pin 56 by conventional means such as an E riny 58. In the preferred mode, the walking beam 54 is pivGtally con-nected at its distal ends to the shutter blade elements 32 and 34 by respective pin members 60 and 62 which extend laterally outward from the walking b~a~ 54. Pin memDers 60 and 62 are preferably circular J.n cross section ; 15 and extend through respective circular openings 64 and 66 in respective blade elements 32 and 34 so as to slidably ; engage respective arcuate slots or tracks 68 and 70 which may be integrally formed within the baseblock casting 12. ~he arcuate tracks 68 and 70 operate to inhibit disengagement of the blade elements 32 and 34 - from their respective pin members 60 and 62 during opera- :
tion of the exposure control system.
A tractive electromagnetic device in the form of a solenoid 72 is employed to displace the shutter blades 32 and 34 with respect to each other and the casting 12. The solenoid 72 includes an internally disposed, cylindrical plunger unit 74 which retracts inwardly into the body of the solenoid upon energization of a solenoid coil or winding ' as sho~n at ~6 in Figure 3. The solenoid plunger 74 may be affixe~ to the walking beam 54 by means of a pivot pin or stud 78 such that longitudinal displacement of the plunger 74 will operate to rotate the walking beam around the pivot pin 56 so as to appropriately displace the shutter blades 32 and 34.
The baGeblock casting 12 supports the solenoid 72 in a position above a biasing tension spring 80 which -~
operates to continuously urge the blade elements 32 and 34 into positions defining their largest effecti~e aper-ture over the light entry exposure opening 16. The movable end of spring 80 is attached to walking beam 54 by a pin 82 while the stationary end of spring 80 is grounded with respect to the baseblock casting 12. Thus, with the spring connection herein described, the exposure control system of this invention is biased to continuously urge the shutter blade elements 32 and 3~ into an open orienta- ;~
tion.
In the present arrangement, the shutter blades 32 and 34 are drawn from their open position to their closed position as shown in Figure 2 when the solenoid 72 is ; ener~ized. Consequently, energization of solenoid 72 prevents the shutt~r blades 32, 3~ from moving towards their maximum aperture opening under the urging of spring `
80. However, as should be readily understood~ the arti-ficial illumination control system of this invention would be equally applicable to photographic systems ~here the blades 32 and 3~ are spring biased in a normally cloæed position.
Continued energization of the solenoid 72 in order . . .
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:. , - ~ . . - . ,: - .: : ~ . ., ., . : .-tL~L33 to maintain the shu-t-ter blade elemen-ts 32 and 34 in their closed positions may result in an undesirable drain ln the camera apparatus power source which preferably is an electrical storage battery schematically shown in Figure 3 at 96. Thus, a mechanical latch as shown generally at 84 may be provided to move into la-teral engagemen-t with an edge of the walking beam 54 so as to maintain the blade elements 32 and 34 in their closed position regardless of the energization of solenoid 72. Additional informa-tion regarding the structure and operation of the latch 84 is described in Canadian Patent Application Serial No. 246,878 by B.K. Johnson, D. Van Allen, and G.D. Whiteside, filed March 1, 1976 and assigned to Polaroid Corporation.
I The photographic camera apparatus 10 is utilized in -I conjuction with a source of artifical illumination which ..
~¦ preferably comprises a linear array of flash lamps as shown generally at 90. The linear flash array includes a plurality of individually spaced apart flash lamps 91 which re- -spectively connect to a plurality of spaeed apart terminal - :
pads or elements 92. The linear flash array 90 may be :~
. releasably eonneeted with respeet to the camera housing ll by way of a reeeiving socket 86 whieh also includes a plurality of spaeed apart terminal pads or elements 88.
~The linear flash array 90 may be inserted and withdrawn -~
` from the reeeiving socket 86 in a manner as is fully described in U.S. Patent No. 3,757,643 enti-tled "Photo-flash Appara-tus" by John Burgarella issued Sep-tember 11, 1973, and assigned in common herewith.
Under conditions of artificial illumination wherein .

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the light ~las a relatively short duration such as from the individual flash lamps 91 of the linear array 90, the anticipated light level at the camera will depend upon the known characteristics of the flash lamps 91 and upon the distance from the subject being photographed to the light source. When the flash array 90 is mounted on the receiving socket ô6, there may be actuated a follow focus system whereby the maximum effective aperture to which the shutter blade elements 32, 34 are allowed to progress is determined in accordance with the distance from the taking lens 18 to the subject being photographed.
~hus, as the focus bezel 22 is rotated to provide the correct focus for a particular distance from the photo-graphic apparatus 10 to the subJect, a follow focus mechanism (shown generally at 174) moves to appropriately displace a ~ollo~ focus interceptor pin 176 about its locus of travel as shown by a phantom line 178. The follow focus interceptor pin 176 may be selectively actu- ;
ated to intercept the edge of walking beam 54 in a well-known manner as is more fully described in Canadian Patent ~o. 1~064,751 which issued on October 23, 1979, by George D. Whiteside, and assi~ned to Pol~roid Corpora-tion. ~hus, as is readily apparent, the walking beam 54 may be intercepted by the follow focus interceptor pin 176 -~
at various locations defining various m~ximum effective apertures which correspond to the distance ~rom ~hich the subject is spaced ~rom the camera apparatus 10.
T~rning now to Fi~ure 3, there is sho~n s schemstic ~. "'' , . ':

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diagram for the artificial illumination control circuitry including a scene light detecting and integrating cir-cuit shown generally at 94. Circuit 94 includes the photo~
responsive element 46 which may be a photovoltaic cell of the type generating an output signal in correspondence with the levels of scene light intensity incident thereon.
The photoresponsive element 46 is orientated to evaluate the light levels of a scene coincident with the field of view of the lens system of the camera and operates in con~unction with the above described aperture scanning arrangement which alters the amount of scene light reaching the photoresponsive element 46 in synchronism and correspond- -ing variation with the progressively changing aperture si~e. The photoresponsive element 46 is coupled with an `
amplifier sta6e 96 along input lines 98 and 100 wherein the amplifier 96 is of a type sometimes referred to in the art -as an "operational amplifier" which may be of a differential variety preferably fabricated in practical miniaturiæed -form. When considered ideally, the ampli~ier 96 has in-finite gain and infinite input impedence and a zero output impedence.
By virtue of a feedback path comprising an inte-gration capacitor 102 connected between the input line 98 . .
and an output line 126 from the operational amplifier 96, the photoresponsive element ~6 is permitted to operate into an apparent low-input impedence so as to function in a current mode, the current generated by the photoresponsive ~-~ element 46 bein6 limited substantially only by its own internal impedence. Thus, under such loading, the photo-responsive element 46 in conjunction with the operational i ~ - 14 -: , amplifier 96 and capacitor 102 is capabl~ of providing a desirable linear output corresponding to the time in-tegration of scene light intensity incident to the photo-responsive element 46.
Any difference of potential supplied by the photo-responsive element 46 across input leads 98 and 100 causes a voltage to be pxoduced at output line 126.
The relatively low signal voltages at the input of amp-lifier 96 which are present with tne relative.y low sig~ ~ :
nal current from the photoresponsive element 46 are acted ;
upon by the correspondingly high gain characteristic of the amplifier. Thus, although the amplifi.er 96 has a very high input impedence, the photoresponsive element 46, when connected in the circuit described, expe.riences only a very low impedence. Therefore, the curren~ output :~
of the photoresponsive element 46 is directe~ into the ~: :.
feedback path.
The initial charging of the integration ~apacitor 102 is synchronized with shutter blade actuation by means of a start cycle latch circuit shown generally at 104 which provides an output actuation signal to the opera-tional amplifier 96 by way of interconnecting line 106.
The start cycle latch circuit 104 is connected to the supply line 108 and ground line 110 by way or Lines 112

2; and 114 respectively and is made responsive to the out- :
put signal from a ripple counter 116 by way of an inter- ..
connecting line 118. The ripple counter 116, in turn, comprises a plurality of serially connected binary cir-cuits 120, each of which can provide an output control signal in a predetermined time sequence as is well known ~ .
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~7~L33 in the art. sinary circuits 120 may be ordinary "flip flops" interconnected in serial relation with respect to each other whereby the binary count r~.e is determined by an oscillator circuit 122 connected thereto by way of a line 124.
The output signal from the light detecting and inte-grating circuit 94 at line 126 is directed to a pair of level detector circuits 130 and 132 by way of inter-connecting lines 126 and 128 respectively wherein level ; 10 detector 130 controls the "fill flash" funct.ion to be subsequently described. Each level detector 130 and 132 --:
may be of any conventional design such as a Schmitt Trigger. As is readily apparent, the steady state reference voltage to tne level detector 130 is established by biàsing means comprising a first resistor 134 con- -nected between the supply line 108 and the input line 126' together with a second resistor 136 connected be-tween the input line 126' and the ground line 110. In - like manner, the steady-state reference voltage level to the detector 132 is established by biasing means comprising a thlrd reslstor 138 connected between the supply line 10~ and the input line 128' and a fourth resj.stor 140 . connected between the input line 128' and the ground line 110 .
The output signal from detector 132 is directed to the base of~an NPN transistor 144 by way of an inter-connecting line 142. The collector of transistor ~44, in turn, is connected to the supply line 108 by way of the solenoid winding 76, while the emitter of transistor 144 is connected to the qround line 110 throuqh resistor 14~. The : -16-~: ~ .. . . .

output signal from the level detector circuit 130 is directed to an OR gate 150 by way of line 148. The output from the OR gate 150 in turn is directed by way of an inter-connecting line 160 to a flash sequencing circuit 162 which will be more fully described in the following dis-cussion. The flash sequencing circuit 162 operatively connects to the linear flash array 90 upon the insertion thereof into the flash array receiving socket ~6. The operative connection is made possible by the ~lurality of spaced àpart terminal pads or elements 88 in the re-ceiving socket 86, which elements are electrically connected to the flash sequencing circuit 162 by way of lines 164 respectively. Thus, insertion of the linear flash array 90 within the receiving socket 86 operates to bring the terminal elements 92 into respective electrical connection with the terminal elements 88. The flash se~uencing circuit 162 thereafter operates to sequentially ignite the individual flashlamps.
A second input signal to thP OR gate 1~0 is derived ~ 20 from an AND gate 154 by way of an interconnecting line - 152. The AND gate 154, in turn, receives an output signal from the ripple counter 116 by way of lines 156 and 158. As is now readily apparent, the output signal from the AND gate 154 is timed to occur at a predetermined interval subsequent to the actuation of the s~art cycle latch 10~, which coincides to the initiation of the actual exposure interval period.
Referring now to Fig.~ there is shown in detail the ~lash sequencing circuit 162, which comprises a plurality of amplifiers 202, 204, 206 and 208 arranged in serial . .
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relationship to respectively driv~ a plurality of NPN
output transistors 210, 212, 214 and 216. The collector terminal of each output transistor, 210 through 216, respectively connects to an output terminal 88. The collector terminal of transistor 210 additionally con-nects to both the supply line 108 hy way of an inter~
connecting resistor 218 and to a latching circuit, shown generally at 222, by way of another intercor.necting re-sistor 220. The latching circuit 222 preferably com prises two NPN transistors, 224 and 226, conrected in common grounded emitter mode. The collectcr terminals of transistors 224 and 226 are also in ~ommon connection, with respect to the input line 230 of amplifier 204.
In like manner, the collector terminal c,f output transistor 212 is connected to both the supply line 108 by way of an lnterconnecting resistor 232 and to the input line of a second latching network 236 by way of another ... ... .
interconnecting resistor 234~ Latching network 236 also comprises two NPN transistors, 238 and 240, connected in common grounded emitter mode. The collector terminals of transistors 238 and 240 are also in common connection to both the supply line 108 by way of an interconnecting resistor 242 and to the input line 246 of amplifier 206. In like manner, the collector terminal of transistor 214 connects to both the supply line 108 by way of an interconnecting resistor 248 and to the input ~f a third ; latching network 252 by way of another interconnecting resistor 250. The latching network 252 comprises two NPN
transistors, 254 and 256, connected in common grounded emitter mode. The collector terminals of transistors .. . . .
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254 and 256 are also in common connectioll with respect to both the supply line 108 by way of an interconnecting resistor 258 and to the lnput terminal of amplifier 208 by way of an input line 260.
The base terminals of transistors 22~, 240 and 256 connect to the collector termi.nal of an NP~ transistor 264 ~y way of a common line 262. The collector of tran-sistor 264 in turn is connected to the supply line 108 by way of a resistor 270. Transistor 264 is controlled tnrough a timing circuit 266, which in turn is controlled from the input line 160 by way of an int~rconnecting line 268.
Thus, as is now readily apparent, insertion of the linear flash array 90 into the flash array receiving socket 86 operates to bring one terminal from each 1ash lamp 91 into respective electrical contact with a terminal element 88 in the flash array receiving socket. The other terminal elements from the flash lamps 91 are in common electrical connection with respect to each other and are connected to the supply line 108 by way of terminal ele-ment 88'. Also, as should be readily apparent, although the flash sequencing circuit 162 is shown as having terminal elements sufficient to accommodate îâ linear flash array having four flash lamps ~1, more or less terminal elements 88 may be included in the flash se-~uencing circuit 162 to accommodate respectively for : more or less individual flash lamps 91 in the linear : flash array 90.
Subsequent to the insertion of the lineal flash ;~ 30 array 90 within the flash array receiving socket 86, , ''~

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~s7~3~3 a low ambient light intensity photographic exposure interval may be commenced upon the aepression of the photo-graphic exposure interval initiating button Sl. As will become readily apparent, the operational sequence for the various embodiments of the exposure control system of this camera are described in relation to a photographic camera of the nonsingle lens reflex type, although the intended '-scope of the invention is by no means so limited and cameras of the well-known reflex type as described in United Sta.tes Patent ~o. 3,672,281 entitled "Reflex Camera"
by E.H. Land may be equally suitable for incorporating the expo~ure control system of this invention. Thus, closure of switch Sl operates to simultaneously move the latch :
84 out of engagement with the edge of the waIking beam 54 in a manner fully described in Canadian Patent Application, Serial No. 246j878, supra, as well as to energize the ;
exposure control circuitry of Figure 3. Disengagement of :
the latch ~4 from the edge of the walking beam 5~ permits :.
tension spring 80 to rotate the walking beam 5~ in a ~ ' clockwise direction as viewed in Figure 2. In this manner, the shutter blade elements 32 and 34 are moved from an initial closed arrangement in directions which operate ~ '~
to progressively enlarge the effective aperture over the light entry exposure opening 16. As should be readily ,: .~ ...: .
understood, in cameras of the single lens reflex type, the blade el'ements must first be closed, and thereaf-ter . :
move from this initial closed arrangement to define an ' :
exposure interval. ~he rotation of the walking beam 54 '~:
. effects simultaneous linear and angular displacement '~
: 30 of the shutter blade elements 32 and 34 about pivot pin 48, ;. .

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so that photocell sweep secondary apertures 40 and 42 simultaneously define a corresponding progressively en-larging ef~ective aperture opening over the photoresponsive element 46.
As is readily apparent, a battery supply voltage across lines 108 and 110 will be maintained only as long as the operator maintains switch Sl in its depressed state, which may be perfectly adequate for situations where the human reaction time in depressing and releasing the switch Sl substantially exceeds the longest exposure time likely to be incurred. However, in situations where the normal exposure time is likely to exceed the human reaction time in depressing and releasing switch Sl, there may be provided a latch circuit, as sho~n generally at 15g, in parallel connection with respect to the switch Sl, for maintaining continuous energization of the exposure control circuit even a~ter the release of the switch Sl A suitable automatic latch circuit is more fully described in United States Patent ~o. 3,7~l~,385 entitled "Control System ~or Photographic Apparatus'l, by Burgarella, et al, issued July 10~ 1973 and assigned in co~mon here-~ith.
Preferably, insertion of the linear flash array 90 within the flash array receiving socket ô6 ~lso operates to actuate the follow focus mechanism 174 so as to move the interceptor pin 176 into the walking beam 5~ locus of travel. As previously discussed, rotation o~ the focus bezel 22 to focus the ob~ective lens 18 also operates to mo~e the interceptor pin 176 along the phantom line 178. ~hus, the maximum ef~ective aperture to which the ., '' , .

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shutter blade elements 32 snd 34 may be progressively opened is limited by the point of interception of the pin 176 with the edge of the walking beam 54.
The photoresponsive element 46 provides an appropriate volitage response corresponding to the scene light intensity incident thereon, which voltage response is thereafter integrated by the operational amplifier 96 and feedback capacitor 102 to provide an output sign~l representative of the time integration of the scene light intensity ,:~
inci dent to the photoresponsive element 46. Under con-ditions of low ambient scene light intensity, the output signal representative of the time integr3tion of the scene light intensity incident to the photoresponsive element 46 will fail to reach the signal le~el required to trigger the level detector 130 prior to the time required for the shutter blade elements to reach their follow focus setting. Thus, after a sufficient time elapses, .
during which the scene light intensity remains inadequate to trigger the level detector 130, the ripple counter 116 ; 20 then provides positive output signals at lines 156 and 15 8 to switch ~he AND gate 154 and provide an output sig-nal at line 152 to the OR gate 150. The OR gate 150, ; in tUrn, switches to provide a flash igniting signal to :
the flash sequencing circuit 162 by way of the inter- :
connecting line 160. : -Referring now to Yig.4, it can be seen that a flash igniting signal is first applied to amplifier 202, which :
in tuxn drives transistor 210 in~o full conduction so as to effect the firing of the first flash lamp 91 in the linear flash array 90. The flash igniting signal at line 160 additionally triggers a timing circ~it 266 so ~ , ~ -22-, as to turn on transistor 264 and thereby simultaneously turn off transistors 226, 240 and 256. In this manner, the latching networks 222, 236 and 252 a.re temp~rarily disabled to permit the energization of the first flash lamp 91. As the first flash lamp 91 is burned, its imped-ence increases so as to drive transistor 210 further into saturation and thereby start to turn tran~istor 224 off.
However, prior to the turning off of transistor 224, which would ultimately turn on transistor 212 by way of amplifier 204, timing circuit 226 operates to turn off transistor 264, in turn, turning on transistors 226, 240 and 256 of respective latching networks 222, 236 and 252. Thus, as is now readily apparent, simultaneously turning on the latching networks 222, 236 and 252 operates to inhibit any further firing of the flash lamps 91.
A subsequent reoccurrence o:E the flash igniting ; signal at line 160 in the course of another photographi~ .
exposure cycle will again operate to drive ,ransistor 210 hard into saturation so as to turn off transistor 224 of latching network 222. Transistors 226, 240 and 256 Pf respective latching networks 222, 236 and 252 are again turned off in the aforementioned manner by way of transistor 264 and timing circuit 266. Thus with both transistors 224 and 226 of latching network 222 turned of~, amplifier 204 is actuated to drive transistor 212 thereby firing the second flash lamp 91 in the linear flash array.
Again, as is readily apparent, continued firing of the second fIash lamp results in a substantial increase in ~` its impedence 50 as to drive transistor 212 further into sat.uration thereby ultimately turning off transistor 238.
`` .
~ -23-, .

.

43;~

~lowever, prior to this occurrence, transistor 240 is again turned on by transistor 264 and timing circuit 266 thereby latching amplifier 206 off. In this manner, each flash lamp 91 may be sequentially fired until the last flash lamp is fired by way of transistor 216. : :.
As should now be readily apparent, the requisite output signals at lines 156 and 158 to fire a flash lamp 91, occur at a predetermined time period, cl~bsequent to the initiation of an exposure interval. The predetermined ~ .
time period is selected to be at least as lo~g as the longest time required for the shutter blade elements 32 and 34 to reach their maximum aperture defining position when tne taking lens 18 is focused to infinity. As should ~ ~
also now be readily apparent, focusing lens 18 at infinity .
oparates to move the follow focus interceptor pin 176 to the largest effective aperture defining po~ition to which the shutter blade elements 32 and 34 can possibly move. In this manner, the shutter blade elements 32 and 34 will always be at rest at their maximum aperture de~
fining position upon energization of the flash array 90.
Subsequent to the energization of an individual ..
flash lamp 91, there will occur a rapid rise in the time integration of the scene light intensity incident to the . :
photoresponsive element 46. The steady state input voltage refèrence level to the detector circuit 132 is biased by the resistors 138 and 140 to esta~li.sh the predetermined value to which the input signal at line ; 128 must increase in order to trigger the level detector 132. Thus, the light intensity is integrated until : 30 reaching a predetermined v~lue corresponding to a select .
~. , ; -~4_ : . ' '. , - ' :. - :

3~
film exposure, at which point the level detector circuit 132 is triggered into an abrupt change of state at the output line 142, from a generally 10W value which is in-sufficien-t to maintain the transistor 144 in conduction, to a su~stantially higher current level of su~ficient value to turn on the transistor 144 and thus establish a current flow from collector to emitter through the tran-sistor 144. Turning on the transistor 1~4, in turn~
operates to energize the solenoid windin~ 76 to retract the plunger unit 74 so as to rotate the walking beam 54 in a counter-clockwise direction, as viewed from Figure 2, against the biasing ~orce of tension spring oO, thereby moving the shutter blade elements into their closed position. A second transistor 145 is also turned on by the level detector 132 simultaneously uith transistor 144 so as to e~fectively ground the flash igniting signal at line 160 for reasons which will become apparent from the follo~ring discussion. APter the walking beam 54 is rotated to its full counter-clockwise position, the latch 84 may be automatically moved into intercepting relation with the edge o~ the walking beam so as to permit the ` deenergization of the solenoid in a manner as is more fully described in Canadian Patent Application Serinl ~o. 246,878 supra. In this manner the exposure interval is terminated.
In situations where the ambient light intensity levels are relatively high, but portions of the photographic sub~ect are relatively dark, the photographic apparatus is capable of operating in a so-called "fill~in ~lash"
mode of opera-tion to provide supplementary illumination in a manner as is more ~ully described in above mentioned .' .
~, . .

Canadian Patent Application Serial No. 262,414. Ho~rever, under conditions o~ increased levels o~ ambient light intensity, the film may receive its correct exposure prior to the aforementioned predetermined time period, in which case the level detector 132 will energize the solenoid winding 76 and retract the solenoid plunger 74 prior to the time in which a flash lamp 91 would other~
wise be energized. ~hus, alternate means are provided for triggering energization of a flash lamp 91 under conditions :~
of relatively high ambient light intensity where the ~ exposure interval would likely be terminated prior to the : predetermined delay period.
~he "fill-in flash" mode o~ operation is commenced :
in the previously described ma~ner upon the depression of the photographic exposure interval initiating button Sl, which operates to simultaneously move the latch 84 ~ :
out of engagement with the walking beam 54 as well as to : .
energize the control circuit of Figure ~. Disengagement :
of the latch 84 from the edge of the waIking bea~ 54 permits the tension in spring 80 to rotate the walking beam 54 in a clockwise direction as viewed in Figure 2 . . .. -.
so as to initiate the exposure inter~al and permit the shutter blade elements 32 and 34 to approach their maximum aperture defining position as limited by the follow focus interceptor pin 176. ~s a result of the increased ambient .
scene light intensity, the time integration of the scene light intensity incident to the photoresponsive element 46 proceeds substantially more rapidly than that for the pre-~.

.

~: .
, . . . .

.. , ": . .. . , .. , , . . . : ..

33~

viously discussed lower ambient scene light intensity situation. The steady state reference voltage signal level to the detector circuit 132 is biased by the resistors 138 and 140 to be above the predetermined value required to trigger the "fill-in flash" level detector 130. As is readily apparent, the predetermined trigger value for detector 130 is selected to be either below or equal to the predetermined trigger value for the level detector 132.
The output voltage signal from the light detecting and integrating circuit 94 at line 126 will now operate to trigger the level detector 130 and thereby change the output signal therefrom at line 148) from a generall~ low value~ to a substantially higher current level of sufficient value to switch the OR gate 150. The output signal at line 160 from the OR gate 150, in turn, is utilized to energize an appropriate flash lamp 91 through the flash sequencing circuit 162 in the aforementioned manner.
As is readily apparent, the linear flash array 90 is now energized at a time prior to which the flash lamp would otherwise have been energized by the output signals at~lines 156 and 158 from the ripple counter 116. The sudden incxease in light intensity attributable to the energization of a flash lamp 91 thereafter operates to ` precipitate a rapid increase in the value of the time integration of the scene light intensity. Thus, in the same manner as previously described, the outp~t voltage signal of the light detècting and integratir,g circuit 94 approaches a value corresponding to the selest film ex-'; ', -: ' ' .
.. .
~ - 27 -~'7gL~

posure, at which point the level dete^tor 132 is triggered to energize the solenoid winding 76. The shutter blade elements 32 and 34 are thereafter returned to their closed positions, terminating the exposure interval.
After the walking beam 54 is rotated to its full counter-clockwise position, the latch 64 may be auto-matically moved into intercepting relation with the edge of the walking beam so as to permit the deenergization of the solenoid as previously discussed.
As is now readily apparent, a race condition is established between the level detector 130 and the ripple ~-counter 116, so that under extremely low levels of ambient scene light intensity, the ripple counter '16 will operate to initiate the energization of a respective flash lamp 91 -at a predetermined time period subsequent tc the initia-tion of the exposure interval. Uncler conditlons of sub-sta~ltially higher ambient scene light intensity, the level detector 130 will operate to initiate the energization of a respective flash lamp 91 as a consequence of the time integration of the scene light intensity to the photore-sponsive element 46 raaching a predetermined value. In this manner, the flash illumination control svstem ma~
be automatically operated in both a normal flash mode of operation and in a "fill-in flash" mode of operation without regard to any external switches or buttons which -would otherwise have to be actuated by the photographer.
It snould also be readily understood that if a respective ~ -flash lamp 91 is energized as a consequence of the level detector 130 being triggered prior to the predetermined time delay established by the ripple counter 116, then , . - , - , . . ..

3~
the subsequent output signal from the ripple counter 116 will operate only to switch the output signal at line 152 from the AMD gate 154, but have no effect on the output signal at line 160 from the OR gate 150. The system as so ~ar described was previously disclosed in Canadian Patent ~pplication Serial Mo. 262,41~, supra.
While flash lamps are perfectly satisfactory sources of artificial illumination, it should be under-stood that other sources of artificial illumination such as strobe, would also be highly desirable for use with the aforementioned exposure control system. It is toward this end that the instant invention is directed.
Electronic photographic strobe devices of the type in which the flash light produced by the flash tube of the device is automatically terminated after a predeter-mined quantity of light has been received from the scene being photographed by a light-responsive controlled portion of the device are known in the art. Such strobes are com-monly re~erred to as quench strobes. In adaition to having an independent light-responsive controlled circuit in the strobe, it is also well known to utilize the exposure control circuits associated with the actual camera ap-paratus to control the firing and quenching of a strobe unit. The strobe ~ire signal may be generated in the identical manner as the previously described flash fire signal, however, whereas the ignition o~ an ordinary ~ ;~
flash lamp is not quenched, aaditional means must be ~-provided to quench the actual ~iring of a strobe. ~oward this end~ it is well known to couple an electronically controlled shutter camera with a quenchable electronic strobe unit so that the strobe unit is quenched simul- - -taneously with the command signal to return the shutter blade elements to their closed position.
Such an arrangement, however, would not be com-patible with the exposure control system herein described, due to the photocell sweep secondary apertures 40 a~d 42 being configured to progressively open ahead of the primary apertures 36 and 38, so that the control circuit prematurely triggers the solenoid to energize prior to the time in which the film is fully exposed. Prematurely triggering the shutter blades to close prior to the time required for full film exposure anticipates for the ad-ditional scene light incident to the film resulting from both shutter blade over-shoot and the finite time required for the shutter blade elements to close. Thu~, quenching the strobe solely as a function of the command signal to close the shutter blade elem~nts will result in an under-exposure since the strobe is quenched instant-aneously and does not provide artificial light during the ~lme required for the opening momentum of the shutter blade elements to be overcome by the solenoid (blade overshoot) and for the shutter blade elements to be thereafter re-turned to their closed position, as is the cas~ for an ordinary flash lamp.
Hence, an additional time delay circuit 300, as shown in Fig.5, must be utilized in conjunction with a quench strobe 400, as shown in Fig.6, so that both the quench strobe 400 and linear flash array 90 can be used inter-changeably with the socket 86. The actual time delay provided by the circuit 300 may be altered as a function of . .
',. : " , ' ' ', ' whether the camera is operated in a "fill-in" flash mode by way of a latch sequencing circuit 161. During the "fill-in" flash mode of operation the time delay in quenching the strobe would generally be decreased so that the shutter blade elements admit less reflected strobe light from the subject during the finite time required for the blades to close. Less reflected strobe light may be re~uired during the "fill-in" flash mode of operation when the subject is already partially illuminated by the ambient background scene light. Conversely, there may also be particular circumstances when an increase in the quench time delay would be desirable during the "fill-in" flash mode of operation. The time delay circuit herein illustrated shows means for accomplishing only a decrease in lS the quench time delay during "fill-in" flash operation although it would be within the scope of the invention to also provide an increase.
The latch sequencing circuit 161 may include two latching circuits, shown generally at 166 and 168, which respectively connect to the collectors of ~PN
transistors 170 and 172 by way of respective lines 178 and 179. Latch circuit 166 comprises a pair of inverter gate~ 192 and 194 wherein the output terminal of inverter gate 192 is tied.to the input terminal of the inverter 25 gate 194 by way of an interconnecting line 198 with the output terminal of inverter gate 194 in turn being tied to the input terminal of inverter gate 192 by way of a line 196. The input terminal of inverter gate 194 also connect-q .~ to ground by way of a capacitor 203.
In like manner, the latch circuit 168 comprises a pair of inverter gates 207 and 209 wherein the output terminal of inverter.gate 207 is tied to the input terminal of inverter gate 209 by way of an interconnecting line 213, and wherein the output terminal of inverter gate 209 is tied to the input terminal of inverter gate 207 by way of an interconnecting line 211. The input terminal to inverter gate 209 connects to ground line 110 by way of a capacitor 217. The emitter of transistor 170 is grounded by way of a line 182 while the collector connects to the supply line 108 by way of a resistor 174 and interconnecting line 176. In addition, the collector of transistor 170 also connects to the output terminal ofthe level detector -130 by way of an interconnecting line 180. In like manner, the emitter of transistor 172 is connected to the ground line 110 by way of an interconnecting line 188 while the collector is tied to the supply line 108 by way of an -interconnecting resistor 184 and line 186. The base terminal for transistor 172 is connected to receive the output signal from latch circuit 166 by way of an ~ :
interconnecting line 205. In addition, the output signal from latch circuit 168 is tied to the base terminal of transistor 170 by way of a line 215. The output sign~l :
from the AND gate 154 is also directed to the collector :~
~0 terminal of transistor 172 by way of an interconnecting line 190. rhe output signal from the latch sequenciny circuit 161 ultimately connects to a terminal element 88"' by way of an interconnecting line 201.
Referring now to Fig. 5, there is shown the schematic diAgram o~ t~e strobe time delay circuit 300 having input terminals 344, 346, 348 and 350 adapted for respective connection with terminal element~ 88', 88, 88"
and 88"' from flash sequencing circuit 162. Across the input terminals 344 and 346~ there is provided a resistor ~.

:, - ~ : .. : . :

302 having an impedence characteristic corresponding with the predetermined characteristic of one of the flash lamps 91. Resis~or 302 is provided for reasons fully explained in United States Patent No.3,858,227 entitled "Adapter Apparatus for Flash Firing System" by Seymour Ellin, et al., issued December 31, 1974.
Input terminal 346 connects to the base terminal of a PNP transistor 306 by way of an interconnecting re-sistor 304. The collector terminal of transistor 306, in turn, connects to both the anode terminal of a diode 310 and to a resistor 308, the other side of which is grounded.
The cathode terminal of diode 310, in turn, connects to one side of a timing capacitor 312, the other side of which is grounded. The cathode terminal of diode 310 also connects to the base of an NPN transistor 316 by way of an interconnecting resistor 314. Transistor 316 is connected in a grounded emitter mode with the col-lector termlnal connected to the input termi.n~l 344 by way of an interconnecting resistor 318. The collector terminal of transistor 316 additionally connects to the anode terminal of a diode 320, the cathode terminal of which connects directly to the base of an NPN transistor 322. The emitter terminal of transistor 322 is connected in common grounded emitter mode with the em tter terminal of another NPN transistor 326. Another timi.r,g capcitor 324 is provided in connection across the collector-emitter terminals of transistors 322 and 326. The base terminal of transistor 326 connects to the collector terminal of ~ransistor 306 by way of an interconnecting resistor 328. The collector terminal~ of transistors 3~2 and 326 33 ~
'~:

connect to the base of a PNP transistor 334 by way of a variable potentiometer 330. The emitter terminal of transistor 334 connects directly to the input terminal 344 while the base terminal of transistor 334 connects to the input terminal 344 by way of an interconnec~ing resistor 332. The collector terminal of transistor 334, in turn, is grounded by way of an interconnecting resistor 336, and additionally connects to the cathode terminal of a diode 338. The anode terminal of diode 338, in turn, n connects to the base of a PNP transistor 340, the collector terminal of which connects directly to the flash quench .
output terminal shown at FQ. The emitter terminal of transistor 340 is in common connection with the emitter terminal of transistor 334 so as to connect directly to the input erminal 344. The flash fire signal is derived .
from the output terminal shown at FF which connects directly to the collector,of transistor 306~ ._ ~he time delay of circuit ~00 may be selectively altered in a manner to be subsequently described through a PNP transistor 352, the emitter terminal of which connects directly to terminal element 344 and the collector terminal of which connects to the base of transistor 334.
The base terminal of transistor 352 connects to the collector terminal, of an NPN transistor 356 by way of a current limiting resistor 354. The emitter terminal of transistor 356 is grounded while the base terminal connect~ directly to the terminal element 350. The ' collector terminal of transistor 356 also connects to the terminal element 344 by way of an interconnecting resistor 358. ".
.
'''~"

~.

Referring now to Fig.6, there is shown a schematic diagram for the quench strobe 400 circuit whi~h may be utilized in conjunction with the strobe time delay cir-cuit 300 of Fig.5. It should be readily understood that the quench strobe circuit 400 is representative of only one of a broad variety of quench strobe circuits which may be utillzed in conjunction with the time delay cir-cuit 300 and which are well known in the art. Other such strobe circuits may be quenched by short circuiting the flash circuit through ignition of a quench tube.
The flash fire terminal FF connects to the base terminal of an ~PN transistor 448 by way of an interconnecting resistor 450. The emitter terminal of transistor 448 is grounded while the collector terminal connects to the base terminal of a PNP transis~or 436 by way of an inter-connecting resistor 446. The base terminal of transistor 436 additionally connects, by way of an interconnecting resistor 442, to a voltage supply Vs which may be associa~-ed with the strobe unit in a well-known manner. The emitter terminal of transistor 436 is conb-ected to ground ~y way of a capacitor 440 and also connects to the posi-tive voltage supply Vs by way of an interconnecting re-sistor 458. The collector terminal of transistor 436, in turn, connects to the gate electrode of a thyristor 422.
The flash fire input terminal FF additionally connects to the gate electrode of a silicon controlled rectifier SCR 414 by way of an interconnecting resistor 420~ The gate electrode of SCR 414 is additionally grounded by way of a oapaci~or 418. The anode terminal of SCR 414, in : . . .

;, - , - . , , :

^9L33 turn, connects to a storage capacitor 402 by way of an interconnecting resistor 416. Between the storage cap-'acitor 402 and thyristor 422, there is interconnected a flash or liyht producing tube 406. A light triggering terminal 408 of the flash tube 406 is coupled through a transformer 410 to one terminal of a capacitor 412.
The other terminal of the capacitor 412 is connected to the anode terminal of the SCR 414. Terminals 452 and 454 are provided for connection to the usual capacitor charging means which is not shown in Fig.6. Such cap-acitor charging means are well known in the art, an~ it is sufficient to say that the capacitor 402 is only main-tained in a charged state by the aforementioned capacitor charging means whereby a relatively high vo-ltage is main-tained across the capacitor 402. Terminal 452 connects to the anode terminal of a diode 404 with the cathode terminal thereof connecting directly to the capacitor

4~2.
Referring now to the flash quench input terminal FQ, it can be seen to connect to the base of a NPN tran-~; sistor 428 by way of an interconnecting resistor 432 Transistor 428 i5 connected in a grounded emitter mode, while the collector terminal thereof connects directly to both the cathode terminal of a diode 43d and to one terminal of a capacitor 426. The anode terminal of diode 430, in turn, is connected to the positive voltage sup-ply Vs by way of an interconnecting resistor 434. The other texminal of capacitor 426 connects to the gate electrode of thyristor 422.
Under conditions where the ambient scene light in- :

' ' tensity is insufficient to provicle an adequate film exposure, the quench strobe 400 may be used in place of tne linear flash array 90 to provide artificial scene illumination. Insertion of the terminals 344 and 346 within the flash array receiving socket 86 may also operate to actuate the follow focus mechanism 150 so as to move the interceptor pin 146 into the walking beam 54 locus of travel as previously discussed. Preferably, terminal elements 344 and 346 from the strobe time delay circuit 300 are brought into respective electrical contact with the terminal elements 88' and 88 from the flash sequencing circuit 162~ In addition, the ground terminal element 348 is brought into electrical contact with terminal element 88" from the flash sequencing circuit 162.
Whereas terminal element 346 may ideally connect to either one or all of the terminal elements 88 from the flash sequencing circuit 162, it is preferred that terminal element 346 electrically connect to the last terminal element 88 from transistor 216 for reasons whi.ch are too ~omplex to be further discussed herein, but wnich are :
readily apparent from United States Paten~ No.3,558,227 supra. Terminal element 350 also connects to terminal88"'.
Subsequent to the insertion of the termlnal elements 344, 346 and 348 from the strobe time delay circuit 300 into the flash array receiving socket 86, a low ambient h light intensity photographic exposure interval may ~e .::-commenced upon the depression of the photographic exposure interval initiating button Sl. Closure of switch S
operates to simultaneously move the latch 84 out of en-gagement with the edge of the walking beam 54 as well ':` ' ' `
~, ~ . ................................. . . .
: ' ': . ' - ' . , .

~3 as ~o energize the exposure co~trol circuitry of Fig.3 in the abov~ described manner. Thus, the shutter blade elements 32 and 34 are permitted to move in directions which operate to progressively enlarge the eLfective aperture over the light entering exposure opening 16.
Rotation of the walking beam 54 effects a simultaneous linear and angular displacement of the shutter blade elements 32 and 34 about pivot pin 48 so that photocell sweep secondary apertures 40 and 42 simultaneously define a corresponding progressively enlarging aperture opening over the photoresponsive element 46.
Upon initiation of an exposure interval, the output signals from the AND gate 154 and the level detector 130 will be considered to be low values approaching ground voltage hereinafter referred to as a logic zero signal level. The initial logic zero signal level at line 180 is thereafter inverted by the yate 192 to a high voltage level hereinafter referred to as a logic one signal level. The logic one signal level at line 198 is again inverted by the gate 194 to provide a logic zero signal level at line 201 which is applied to the terminal element 350 of timing circuit 300 thereby turning ;
of transistors 356 and 352. In addition, the logic zero output signal from gate 194 is also applied to the base of transistor 172 by way of line 205 so as to turn of transistor 172.
At the initiation of the exposure interval, the output signal from the AND gate 154 at line 190 also assume~ a logic zero signal ~evel which is inverted by the gate 207 to provide a logic one signal level~at line .

~7~33 213. The logic one signal level at line 213 is again inverted by the gate 209 to provide a logic zero output signal level at the base of transistor 170 so as to turn off transistor 170.
The photoresponsive element 46 again provides an appropriate voltage response corre~ponding to the scene light intensity incident thereon~ which voltage response is thereafter integrated by the operational amplifier 96 and feedback capacitor 102 to provide an output signal representative of the time integration of the scene light intensity incident to the photoresponsive element 46. As is readily apparent, the low ambient light intensity ~mains su~stantially constant during the time required for the shutter blade elements to reach their follow focus setting and for a predetermined period thereafter at which time the ripple counter 116 provides positive output signals at lines 156 and 158 to switch the AND gate 154 and providé a positive output signal at line 152 to the OR gate 150. The OR gate 150, in turn, switches to provide a positive flAsh igniting signal to the flash sequencing circuit 162 by way of interconnecting line 160.
Referring now to Fig. 5, it can be seen that the resistor 302, having an impedance characteristic corresponding with the predetermined impedance characteristic of an unfired flash lamp, is effectively connected between the terminal element 88' and the terminal element 88 from the collector of transistor 216. ThusJ a high input ~ignal level at line 160 will operate to turn on transistor 216 in a manner as previously described.
The appearance of the positive output signal from ` . ' .
. .

., .......... ............................................................. ... .-the AND gate 154 at lines 152 and 190 is also equivalent to a change from a logic zero signal level to a logic one signal level. The change in logic levels is thereafter inverted by gate 207 to provide a logic zero signal level at line 213 which signal level is again inverted by gate 209 to provide a logic one output signal level at line 215 thereby forward biasing the base-emitter junction of transistor 170. In this mannerJ
transistor 170 is turned on to effectively tie line 180 to ground line 110 for the remainder of the exposure interval regardless of whether the input voltage level to the deteator 130 thereafter reaches its predetermined trigger level. Since the input voltage level to the latch circuit 166 remains effectively tied to ground for the remainder of the exposure interval, the logic zero output signal level at line 201 will also continue to maintain the tranqistors 356 and 352 in their cutoff state for the remainder of the exposure lnterval.
Referring now to the strobe time delay circuit 300 of Fig. 5, it can be seen to assume the following condition immediately prior to the turning on of transistor 216.
Immediately prior to transistor 216 being turned on, transistor 306 is in a nonconductive state, in turn, causing transistors 316 and 326 to assume similar non-conductive state~. With transistor 316 being off, tran-sistor 322 assumes a conductive state so as to effect-ively short out capacitor 324 while als~ turning on transistor 334. With transistor 334 conducting, transistor -:- - . ~ . . -340 assumes a nonconductive state to provide a substantially zero output signal level at the flash quench terminal FQ. In like manner, with transistor 306 off, a sub-stantially æero output signal level is also provided at the flash fire terminals FF.
With the turning on of transistor 216 from the flash sequensing circuit 162, transistor 306 of the strobe time delay circuit 300 also turns on at time Tl so as to provide a positive flash fire signal level at the ~lash fire terminals FF as shown graphically in Fig.7. Turning on transistor 306 also results in transistor 316 turning on with transistor 322 being turned off. Capacitor 324, however, remains effectively short circuited by transistor 326 which is turned on simultaneously with transistor 306.
Thus, the output signal at the flash quench terminals FQ
remains unaffected by the turning on of transistor 306.
Referring now to the quench strobe diagram of Fig.6, it can be seen that a positive flash fire signal operates to turn on transistor 448 while a:Lso turning on transistor 436. Thus, a current will flow from capacitor 440 through the emitter collector junction of transistor 436 to the gate electrode of thyristor 422 thereby rendering it conductive. When the SCR 414 becomes conductive, a a lower resistance discharge path is presented across the capacitor 412 which causes the capacitor to dump its charge so as to trigger the flash tube 406. As the flash tube 406 begins to conduct, the voltage on the high voltage termin~l 452 may be reduced as the charge -~ on the capacitor 402 is dumped through the flash tube ~. .... .
406.
~ ' .

.

L3~?b Subsequent to the firing of flash tube 406, there ls again incurred a rapid rise in the time integratlon of the scene light intensity incident to the photoresponsive element 46. As previously discussed, the steady state input voltage reference level to the detector circuit 132 is biased by the resistors 138 and 140 to establish the predetermined value to which the input signal at line 126 and 128 must increase in order to trigger the level de-tector 132. Thus, the light intensity is in~egrated until reaching the predetermined value at which point the level detector circuit 132 is triggered into an abrupt change of state at the output line 142, from a generally low signal value which is insufficient to maintain the transistors 144 and 145 in conduction, to a s~stantially higher current level of sufficient value to turn on the transistors 144 and 145. Turning on the transistor 144, i in turn, operates to energize the solenoid winding 76 to retract the plunger unit 74 so as to rotate ~he walking beam 54 in a counter-clockwise direction, as viewed from 2n Fig.2, against the biasing force of tension spring 80, thereby moving the shutter blade elements into their light blocking alosed position. After the walking heam 54 is ro~ated to its full counter-clockwise position, the latch 84 may be automatically moved into intercep~ing relation with the edge of the walking beam so as to permit the deenergization of solenoid in the above described manner.
Turning on transistor 145 operates to effectively ground th~ input signal at line 160 to the flash sequencing circuit 162. Effectively grounding the in~ut signal at ~: .

, :

llne 160, in turn, operates to turn transistor 216 off thereby turning transistor 306 of the stlobe time delay circuit 300 off so as to remove the flash flre signal at time T2 as shown in the graph of Figure 7. Turning transistor 306 off also operates to turn transistor 326 off so as to allow capacitor 324 to start to charge.
Transistor 322 remains off to permit capacitor 324 to charge by virtue of the capacitor 312 which discharges through resistor 314 and the base-emitter ju~ction of transistor 316 so as to maintain transistor 316 turned on thereby keeping transistor 322 off. As is readily apparent, dlode 310 prevents capacitor 312 from dis-charging through resiqtor 308. Thus, capaci~or 324 is charged through resistor 332 and potentiometer 330 until reaching the threshold ~oltage required to turn off transistor 334 and thereby turn on transistor 340.
~urning ~n transistor 340 provides the flash quench signal a time T3 as shown graphically in Fiy.7. As is now readily apparent, the flash quench signal appears at a time T3 subsequent to the termlnation of the flash -fire signal at T2 which time also corresponds to the com-mand signal from the level detector 132 for energizing the solenoid winding 76 to close the shutter hlade ele-ments. The time delay from T2 to T3 is determined by the RC time constant of the capacitor 324 and the resistor 332 in series with the potentiometer 330. Thus, the user may vary the time delay from T2 to T3 by adjusting the potentiometer 330. As is now readily apparent, the flash quench signal is also of limited duration as a result of the time required for capacitox 312 to discharge .~ ' ~ '' .

3~

through the resistor 314 and the base-emitter junction of transistor 316. Thus, once capacitor 312 is discharged, transistor 316 turns off thereby turning on transistor 322 so as to effectively short capacitor 324. With capacitor 324 once again effectively shorted, transistor 334 turns on so as to turn off transistor 340 and return the output signal at the flash quench terminals back to a low value, as shown at T4 in Figure 7.
Referring now to the strobe circuit 400 of Fig.6, it can be seen that the appearance of the flash fire signal operated to turn on transistor 448 thereby also turning on transistor 436 so as to cause a current flow through the emitter collector ~unction thereof into the gate electrode o thyristor 422 thereby rendering it con-ductive. At the same time, the flash fire signal was also applied, by way of resistor 420, to the gate electrode of SCR 414 thereby rendering it conductive. When the SCR 414 becomes conductive, a Iow resistance discharge path is presented for the capacitor 412 which causes the capacitor 412 to dump its charge. That action induces a triggering signal to appear at the flash tube triggering terminal 408 thereby initiating conduction in ~he flash tube 406. Thus the flash tube is fired at 1'1 in cor-respondence wi~h the leading.edge of the flash fire signal as shown in the diagram of Fig.7, as previously discussed.
It should be readily appreciated that capacitor 426 is charged by way o resistor 434 and diode 430 with the positive terminal of the capacitor 426 connecting di-rectly to the cathode of diode 430 and the collector of transistor 428. The subsequent appearance of the flash -~ .
.' quench signal at tim~ T3 after the pre~eter~ined time delay, operates to turn on transistor 428 thereby ef-fectively grounding the positive terminal side of the capacitor of 426. With the positive terminal side of capacitor 426 grounded, the negative terminal side then drops to a voltage level below ground which negative voltage is applied directly to the gate elec~rode of thyristor 422 so as to render thyristor 422 ~onconductive and thereby quench flash tube 406.
Thus it can be seen that durinq the low amnient light mode of operation, the 1ash tube 406 is quenched subsequent to the expiration of a first predetermined time periocl after the triggering of level detector 132 and the enexgization of the solenoid winding 72 to retract the shutter blade elements to their closed position. The first predetermined time delay is selected so that the additional scene light admitted from the quench strobe subsequent to the triggering of detector 132 closely approximates the additional scene light which would otherwise be admitted by an ordinary flash lamp. In this mannerl the aforementioned anticipation characteristic of the photocell secondary apertures 40 and 42 which accommodates for the additional scene light admitted through the primary apertures 36 and 38 during the time required for the shutter blade elements to move to their closed position, is e~ectively correlated to the predetermined time delay to accommodate for the quench strobe which artificial light output may be substantially instantaneously terminated.

. -- ~5 -: ~ -':,. '. '" . .-., ' ~ . ' ' ' ,. . , ' ,, : , ,~ :

The predetermined time ~elay also, by insuring that at least a portion of the scene light from the strobe is admitted during the finite shutter blade closing time, effectively compensates for variations in background scene brightness in the manner of an ordinary flash lamp. Thus, with a brighter than average scene background, the shutter blade elements are triggered to close early on the rising portion of the flash curve so that more scene lig~t is admitted during the finite blade closing time thereby better exposing a subject's face against the bright background. Conversely, with a darker than average scene background~ the shutter blade elements are triggered to close later on the falling portion of the flash curve so that less scene light is admitted during the finite --blade closing time thereby better exposing a subject's face against the dark background.
The photographic apparatus is also capable of operating in the aforementioned "fill-in flash" mode of operation to provide supplementary illumination in ~0 situations ~here the ambient scene light intensity levels are relatively high. During the "fill-in flash" mode of operation) the first predetermined time delay is ` automatically shortened in the following manner in order to effectively compensate for the increased ambient scene light intensity. Thus the "fill-in flash" mode of operation is commenced in the previously described manner upon the depression of the photographic exposure interval initiating button Sl which operates to release the walking beam 54 and to energize the control circuit of Fig. 3 in the aforementioned manner~ The shutter blade elements 32 ., , . .. , . ,.,. : ~

and 34 are moved by the tension spring 80 toward their maximulll aperture defining position as l~ ited by the follow focus interceptor pin 176. As a result of the increasing ambient liyht intensity, the time integratiorl of the scene light intensity incident to the photoresponsive element ~6 pro~eeds substantially more rapidly than that for the previously discussed lower amhient scene light intensity situation. Thus the output voltage signal from ., the li.g~t detecting and integrating circuit 94 at line 126 will operate to cause the level detector 130 to ~ .' trigger and thereby change the output signal therefrom at li.ne 1.48 from a generally low value to a subs-tantia.l.l.y ' '''' higher current level of sufficient value to switch the OR
gate 1.50.
The change from a logic zero output signal : level to a logic one output signal level at line 180 ,~, is inverted by the gate 192 to provide a logic zero s.ignal level at line 198 which is again inverted by gate 194 to provi.de a logic one output signal level at line 201 so as to forward bias the base-emitter junction of transistor 356 in Fig. 5 thereby turning on transistor 352 to establish a collector to emitter current flow.
The h.igh logic one output signal level from gate 194 ls ' :
; also transmitted to the base of transistor 172 by way of ~.
line 205 so as to ~imultaneously turn on transistor 172 ' ' thereby ef~ectively tying line 190 to ground line 110, ' ~' ' Thus) if the i.nput signal levels at lines 156 and 158 should reach the requisite levels to switch the AN:D gate '~ :
: 154 subs~quent to the triggering of the level detector 130, but prior to the triggering of the level detector 132, '' ~. .
,' .
~ - 47 ~

the output signal at line 152 from the gate 154 will never-theless remain tied substantially to the ground line 110 by way of the lines 190 and 188 together with the forward biased collector-emitter junction of transistor 172.
In this manner, the quench time delay may be selectively altered as a result of the exposure control system being operated in a "fill-in flash" mode of operation. As is now readily apparent, turning on transistor 352 operates to effectively short out resistor 332 thereby reducing the RC time constant associated with the capacitor 324. Thus, a second, shorter, predetermined strobe quench time delay is automatically p.rovided in response to the "fill-in flash" mode of operation in order to compensate for the increased ambient scene light intensity as shown graphically in Fig. 7.
~he output signal at line 160 from the OR
gate 150, operates to flash the flash tube 406 through the flash sequencing circuit 162 and the strobe time delay circuit 300 as previously discussed. Subsequent :
triggering of the level detector 132 as a result of the increased scene light from the flash tube 406 will thereafter operate to quench the strobe after the second~ shorter~ predetermined time delay in the aforementioned manner.
It should be readily understood that although the time delay circuit 300 has been shown and described as having terminal elements insertable within the flash array receiving socket 86, it may alternatively be provided as ' .~ - .

either an integral part of the camera control circuit or the ~trobe circuitry. In addition, a unitary camera apparatus may be provided with both an integral strobe unit and an integral time delay circuit as shown in Fig. 5. In addition, the time delay circuit may exist independently of either the camera or strobe. In addition, the latch se~uencing circuit could also be made an integral part of either the time delay circuit 300 or the strobe 400.
Since certain changes may be made in the above described system and apparatus without departing frcm the scope of the invention herein involved, it is intended that all matter contained, this scription thereof, or shown in the accompanying drawings shall be interpreted as illustrated and not in a limiting sense.

..
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A photographic camera comprising a housing; means for electrical connection to a source of artificial illumination; a blade assembly arranged within the housing for displacement from an initial closed arrangement wherein the blade assembly precludes scene light from impinging on an exposure plane to a second arrangement wherein the blade assembly defines a maximum aperture for the passage of scene light and then to a final closed arrangement, such a displacement of the blade assembly serving to define an exposure interval; scene-light detecting means for providing an output signal in correspondence with the integrated amount of scene light detected subsequent to the commencement of an exposure interval; and means for initiating the displacement of the blade assembly from its initial closed arrangement towards its second arrangement thereby commencing the exposure interval and for initiating the energizing of the source of artificial illumination to effect the firing thereof subsequent to the initiation of the exposure interval and then, responsive to the output signal of the scene-light detecting means reaching a predetermined value, for effecting the dis-placement of the blade assembly into its final closed arrangement and for initiating the de-energization of the source of artificial illumination to effect the termination of the firing thereof subsequent to the expiration of a selected time delay commencing immediately after the output signal of the scene-light detecting means reaches the said predetermined value.

2. A photographic camera in accordance with claim 1, wherein the last-stated means provides a first signal when the camera is electrically connected to the source of illumination to initiate the energization of the source of artificial illumina-tion and a second signal subsequent to the expiration of the selected time delay, the second signal being operative to initiate the de-energization of the source of artificial illumination.

3. A photographic camera according to claim 2, in which the last-stated means further includes means for varying the said selected time delay as a function of the ambient bright-ness prior to the firing of the said source of artificial illumination.

4. A photographic camera according to claim 3, wherein the means for varying the selected time delay operates to decrease the selected time delay in response to the said output signal of the scene-light detecting means reaching a selected value within a predetermined period.

5. A photographic camera according to claim 3, wherein the last-stated means is responsive to the output signal of the scene-light detecting means reaching a first predetermined value for initiating the energization of the source of artificial illumination to effect the firing thereof and is otherwise respon-sive to the expiration of a first predetermined time delay for initiating the energization of the source of artificial illumina-tion to effect the firing thereof when the output signal of the scene-light detecting means fails to reach the said first pre-determined value prior to the expiration of the first predetermined time delay, and is further responsive to the output signal of the scene-light detecting means reaching a second predetermined value greater than the first predetermined value for effecting the dis-placement of the blade assembly into its said final closed arrangement and for initiating the de-energization of the source of artificial illumination to effect the termination of the firing thereof subsequent to the expiration of either a second or third predetermined time delay after the scene-light detecting means reaches the said second predetermined value, the second pre-determined time delay occurring in response to the output signal of said scene-light detecting means reaching the said first pre-determined value in time to initiate the energization of the source of artificial illumination and the third predetermined time delay occurring in response to energization of the said source of artificial illumination at the expiration of the first predetermined time delay.

6. A photographic camera according to claim 5, wherein the said second predetermined time delay is greater than the said third predetermined time delay.

7. A photographic camera in accordance with claim 1, wherein the source of artificial illumination is an electronic flash tube.

8. A photographic camera in accordance with claim 7, wherein said last-stated means includes a capacitor for energizing the source of artificial illumination, a switch for initiating the discharge of the capacitor through the flash tube, and means for prohibiting further discharge of the capacitor through the flash tube for initiating the de-energization of the source of artificial illumination.

9. A photographic camera in accordance with claim 1, wherein the blade assembly includes two shutter blade elements having respective primary and secondary apertures there-through wherein the primary apertures during shutter blade displacement cooperatively define a first effective aperture for admitting scene light to the exposure plane and wherein the secondary apertures move in correspondence with the primary apertures and cooperatively define a second effective aperture for admitting scene light to the scene-light detecting means, the second effec-tive aperture having an anticipated characteristic with respect to the first effective aperture to which the said predetermined time delay is correlated in order to effect the termination of the firing of the source of artificial illumination when the correct exposure value is achieved.

10. A photographic camera in accordance with claim 1, in which the camera includes means for receiving the source of artificial illumination within the camera housing.

11. Lighting apparatus for use with a photographic camera of the type having means for providing at least two control signals in sequence during the course of a photographic interval, the lighting apparatus comprising: a source of artificial illumina-tion; means for accommodating at least one electrical connection from the lighting apparatus to the camera in order to facilitate the transmission of the two signals from the camera to the light-ing apparatus; means for coupling to a source of electrical energy and means energizable by the source of electrical energy, and responsive to the first of the two signals from the camera for initiating the energization of the source of artificial illumina-tion to effect the firing thereof; and then responsive to the second of the two signals from the camera for initiating the de-energization of the source of artificial illumination sub-sequent to the expiration of a predetermined time delay after receipt of the second of the two signals from the camera.

12. Lighting apparatus according to claim 11, for use with a photographic camera wherein the timing of the first of the two control signals varies as a function of ambient brightness and the timing of the second of the two control signals indicates that a predetermined film exposure value has been reached, the light apparatus additionally comprising means for adjusting the said selected time delay according to the timing of the first of the two signals.

13. Lighting apparatus according to claim 12, wherein the timing of the first of the control signals is governed by an output signal from scene-light detecting means within the photo-graphic camera which represents the amount of scene light detected within a predetermined period.

14. Lighting apparatus according to claim 11, in com-bination with a camera including: a blade assembly mounted and arranged within the housing for displacement from an initial closed arrangement wherein the blade assembly precludes scene light from impinging on the exposure plane to a second arrangement wherein the blade assembly defines a maximum aperture through which scene light is permitted to impinge on the exposure plane and then to a final closed arrangement wherein the blade assembly again pre-cludes scene light from impinging on the exposure plane, such a displacement of the blade assembly serving to define an exposure interval during which scene light is incident upon the film exposure plane, wherein the blade assembly includes two shutter blade elements having respective primary and secondary apertures therethrough wherein the primary apertures during shutter blade displacement cooperatively define a first effective aperture for admitting scene light to the exposure plane and wherein the secondary apertures move in correspondence with the primary apertures and cooperatively define a second effective aperture having an anticipation characteristic with respect to the first effective aperture; and scene-light detecting means energizable by the source of electrical energy for providing an output signal in correspondence with the amount of scene light detected through the second effective aperture subsequent to the commencement of an exposure interval; and wherein the predetermined time delay is correlated to the anticipation characteristic in order to effect the termination of the firing of the source of artificial illumination when the correct exposure value is achieved.