US2911809A

US2911809A - Photographic flashlight apparatus

Info

Publication number: US2911809A
Application number: US547280A
Authority: US
Inventors: Nojiri Tatuo
Original assignee: Canon Camera Co Inc
Current assignee: Canon Inc
Priority date: 1955-06-08
Filing date: 1955-11-16
Publication date: 1959-11-10
Anticipated expiration: 1976-11-10

Description

Nov. 10, 1959 TATuo. NOJlRl PHOTOGRAPHIC FLASHLIGHT APPARATUS Filed Nov. 16, 1955 /N VEN TOR TA TUO NOJ/R/ AT TORNE V United States Patent() PHOTOGRAPHIC FLASHLIGHT APPARATUS Tatuo Nojiri, Setagayaku, Tokyo, Japan, assignor to Canon Camera Company, Inc., Otaku, Tokyo, Japan, a corporation of Japan Application November 16, 1955, Serial No. 547,280

Claims priority, application Japan June 8, 1955 7 Claims. (Cl. 67-31) The instant invention relates to flashlight apparatus for photography by flash exposure.

An object of the instant invention is to provide a test circuit which includes a ilashbulb and a condenser ina sub-flashlight circuit for B-C type main-flashlight apparatus.

Another object of the invention is automatically to maintain the charging circuit open when a flashlight is not 'inserted in the socket therefor thereby eliminating unnecessary drain on the battery.

A clearer concept of the features, objects and scope of the instant invention will be obtained from the following description of illustrative embodiments thereof when read in conjunction with the appended drawing, in which:

Figure 1 is the electrical circuit diagram of a first illustrative embodiment of the flashlight apparatus according to the instant invention having a test circuit by which two tests of the flash lamp can be made, in which diagram while the charging switches are shown the charging generator circuit is omitted;

Figure 2 is a longitudinal section of a second illustrative embodiment of the flashlight apparatus according to the invention provided with means to eliminate unnecessary drain on the battery when the ashlight attachment is removed from the camera. Y

Referring to Figure 1', a charging condenser 1 has connected thereto a battery 2 by way of series resistor 3 to form the charging circuit including switch contacts 4, 5 which open the charging circuit when the ilashlight attachment or the extension cord thereof is removed from the camera socket therefor and which close it on insertion of the attachment or extension cord'in such socket on the camera as below described in detail in connection with Figure 2. A iiashlamp socket 6 is connected between one side of condenser 1 and terminal 7 of the pair of terminals 7, 8, the other terminal 8 of the pair being connected to the otherterminal of condenser 1. Terminals 7 and 8, on insertion of the ashlight attachment into the camera socket, connect to the ignition switch 9. With a ilashlamp inserted in socket 6, the discharge circuit is thus switch 9, terminal 7, socket 6, condenser 1 and terminal 8.

A normally open test switch 10 has its movable arm electrically connected to a connector between terminal 7 and socket 6and its fixed contact 11 connected to a test lamp 12. Lamp 12 in turn is connected to the movable arm 13 of a two-throw switch, arm 13 being adapted sselectively to engage fixed contacts 14 and 15 of the twothrow switch, fixed contacts 14 and 15 being connected to opposite sides of condenser 1. Movable arm 13 of the two-throw switch is mechanically connected, by the rigid link 16 of insulating material to the spring-biased, central and movable terminal 17 extending through an aperture in the bottom of socket 6. While arm 13 is thus electrically insulated from terminal 17, the latter at its portion extending below socket 6, is electrically contiected to the same side kof condenser 1 as is fixed con- Hee 2. tact 14. Spring 18 biases the terminal 17 upwardly within socket 6 an amount suicient to close arm 13 on contact 14 when there is no flash-bulb inserted in the socket. However, when a ash-bulb is inserted into the socket, central terminal 17 is depressed an amount sutlcient Vfor arm 13 to leave contact 14 and to engage fixed contact 15.

With the iiashlight attachment inserted into the socket provided therefor in the camera, that is, the terminals 7 and 8 connected to terminals 20 and 21 respectively on the camera, which latter terminals in turn are electrically connected in circuit with the ignition switch 9, a bulb 22 inserted in socket 6 may be tired as in conventional fiash apparatus on closing ignition switch 9. In addition, the instant apparatus permits two desirable tests to be made of the operativeness of the firing circuit. For the first test, while the attachment is inserted into its camera socket, thus closing switch contacts 4 and 5 on each other, no ashbulb is inserted in socket 6. Test switch movable arm 10 is now manually closed on contact 11, and thereupon ignition switch 9 is closed in suitable manner, as by actuating the camera shutter release button. In that movable arm 13 of the two-throw switch is now closed on contact 14, the circuit comprising condenser 1, contact 14, test lamp 12, terminal 7,

terminal 20, ignition switch 9, terminal 21, terminal 8 back to condenser 1, is closed and the test lamp lights up, indicating that the flash circuit is functioning properly. For the second test, a iiashbulb 22 is inserted in socket 6 and the test switch movable arm 10 closed on fixed contact 11. Now the movable arm 13 engages iixed contact 15 and the closed circuit is condenser 1, central terminal 17, ashbulb 22, socket 6, movable arm 10, contact 11, test lamp 12, movable arm 13, contact 15, back to condenser 1, lighting test lamp 12. The current through this closed circuit is not ofv suiiicient magnitude due to the resistance of test lamp 12, and the lighting of the test lamp indicates that the ashbulb is in perfect condition since the flashbulb is an integral series element of this closed circuit. It is thus obvious that both tests impart visual information as to the condition of the electrical source, battery 2, in accordance with the brightness with which test lamp 12 lights up. It will be noted that auxiliary terminals 7 and 8', serially connected to terminals 7 and 8 respectively as shown in Figure 1, permit the testing of sub-tiashbulb apparatus connected to such auxiliary terminals.

It follows that the flashlight `apparatus of the instant invention has the advantage of incorporating integral test circuits derived from the electrical connections between the flashbulb socket and the ignition switch beingl ,the mere insertion of a tiashbulb into its socket. A

unique feature of the instant apparatus is the elimination of any accidental ignition of the ashbulb, since testing of the tlaslibulb is made while inserting it into its socket, and testing of the circuit can be made only without any -liashbulb in the socket, that is, completely independent of the flashbulb.

Referringv now to Figure 2, showing a longitudinal section of an actual embodiment of the flashlight apparatus in the form of an attachment which may be used either directly aixed to acamera or connected thereto by a cord, the portions of the camera 23 necessary for a clear understanding are Shown in the right hand portion of such ligure. A metal cup-shaped bushing 24 is mounted in, and extends through a lateral portion of the camera, and has an external, formed bayonet flange 25 to which, as below described, the flashlight attachment may be rigidly alixed; The ignition switch 9 and terminals 20, 21 connected thereto are within the camera body and are indicated diagrammatically in Figure 2. A rod 26, hereafter referred to as the central terminal, is electrically connected to terminal 21 and extends outwardly through an insulating sleeve 26a disposed in an annular extension 24a Within bushing 24 so that its external end is substantially flush with the plane of the formed llange 25 thereof. The bushing 24 is electrically connected to terminal 20. The outer diameter of the annular extension 24a of the bushing 24 is such that the outer conductor of standard extension cords for flashlight devices snugly fits thereover to make intimate electrical contact therewith while the central terminal 26 engages the inner conductor of such extension' cord.

All the other elements of the flash circuit of Figure l, except ignition switch 9 and terminals 20, 21, in the embodiment of Figure 2 are in the relatively elongated housing 27 .of electrical insulating material, which has a removable back of the usual type, not shown, for ready access to theelements for replacement, particularly the battery. One end of the housing 27 is provided with means for latching the flashlight housing directly to the camera bushing 24, an adjacent portion of the housing being so constituted that the flash equipment, positioned remote from the camera, may, nevertheless, be connected to the camera by a standard ash extension cord engageable to the external end of coaxial line 26 within bushing 24. A formed locking ring 28 has an internally threaded bore and is rotatably disposed on sleeve 29 mounted into the end wall of housing 27 and projecting outwardly therefrom. Metal sleeve 29 has an annular external shoulder 30 integral therewith and fitting into an annular recess 31 in the outer face of the end wall about a bore 32 through such end wall at a relatively thick portion thereof. A flanged metal bushing 33 has its outer surface threaded to mesh with the adjacent threaded inner surface portion of sleeve 29, so that on threading bushing 33 tight on sleeve 29, sleeve29 is tightly clamped by shoulder 30 against groove 31 in the housing end wall. While the locking ring 28 may be of non-conductive material it is preferably of metal in view of the forces to which it is subjected when connected to bushing 24 and supporting the weight of the attachment and the inserted llashbulb. The forward portion 34 of locking ring 28 is an internally extending flange spaced axially from the adjacent end of the internal threading of the locking ring so that ilange 25 of attachment bushing 24 on the camera may be clamped` tightly between the outer end face of sleeve 29 and the inner face of flange 34 on rotation of the locking ring, preferably a quarter of a turn. The internal aperture delined by flange 34 is of such dimensions and has such form of itsgperiphery that liange 25 readily passes thereinto when aligned and registered therewith, and locks with Flange 34 on such quarter turn of ring 28 on sleeve 29.

On the axis of bore 32 and coaxially Within sleeve 29 and bushing 33, a metal rod 35 is positioned so that the conductors thereof, on locking llange 34 to llange 25, are in electrical contact with the corresponding conductors of `coaxial line 26. Support bushing 36 fitting snugly into the bore 32 within sleeve 29 has a central aperture in which rod 35 is a smooth sliding fit. Near its end the closer to flange 34, the rod 35 has an annular shoulder37, a coiled spring 38 being biased between support bushing 36 and rod shoulder 37, tends to force bushing 36 against the adjacent end of spatially xed bushing 33 and rod shoulder 37 against the base of cupshaped insulating sleeve 39 through which the engaging end of rod 35 slidingly extends, the cup-shaped sleeve 39 being prevented from moving by an inner annular shoulder 4t) at the outer end of spatially xed sleeve 29. The engaging end of rod 35 is of such length that when its outer end engages the central terminal 26, the spring 38 is compressed on locking flange 25 to flange 34, and rod 35 is displaced along its axis sufcient to close a contact as will immediately be described, such movement being to the left in Figure 2.

The rod 35 extends with its end remote from its locking end into the housing 27, into an interior compartment through one wall of which extend two conductive bushings `4i and 42 adapted to receive the plug ends 43 and 44, of the conductors of anextension cord 45 when using the instant llash attachment positioned at a point remote from camera 23. One conductive bushing 4Z is connected electrically by an electrical connector 40 to metal bushing 33, which in turn is electrically connected to socket 6. The other conductive bushing 41 is electrically connected to one side of battery 2 by a formed conductor 47 of springy material, and mechanically supported by a portion of the housing, which beyond the battery 2 terminates in a Contact 48 of inverted V- or hairpin-shape. The projecting end of rod 35 within the housing is electrically connected to an intermediate unsupported region of electrical connector 49 of spring material, mechanically supported at an end making electrical contact with one side of condenser 1, and of such form that its other end is engageable by plug 43 on insertion into bushing 41. A stop pin 50 of insulating material prevents both the intermediate region and the free end region of conductor .49 from being deflected other than in the intended way, respectively to engage contact 48 by the intermediate region of 49, and to engage the free end region of conductor 49 to plug 43.

When the flange 25 is locked to flange 34, the rod 35 is displaced axially to the left in Fig. 2, the intermediate region of connector 49 engaging the contact 48 to complete the circuit through battery 2 to permit condenser 3 to be charged, the charging circuit being obvious in Fig. 2. The tiring circuit for llashbulb 22 is also obvious in Fig. 2, the movable contact of ignition switch 9 being connected through bushing 24, sleeve 29 when the flashlight attachment is secured, through bushing 33, and conductor 51 shown connected by phantom line to socket 6, the terminal 17 being connected by conductor 52, shown in phantom line, to one side of capacitor 1. The other side of the capacitor isconnected by conductor 49 to rod 35, through central terminal 26 to the lixed contact of the ignition switch 9. i y

When using the flash attachment of the instant invention positioned remote from the camera, the contact 48 is obviously not in engagement with the intermediate region of conductor 49 since the rod 35 is biased away therefrom by spring 38, and the circuit from battery 2v to condenser 1 is open, so that there is no drain upon the battery. Only when the plug 43 of connector cord 45 has been inserted fully into conductive bushing 41 (and plug 44 in bushing 42) after the other'rend (not shown) of the standard flashlight cord 45 has been connected to cable 26, is such connection made by way of connector 47, bushing 41, plug 43 and connector 49, by virtue of the engagement of the free end of plug 43 with the free end of conductor 49. Thus no matter in which of the two positions-direct mechanical attachment or remote from the camera-the flashlight circuit of the invention is used, the

battery toV condenser circuit is completed automatically and simultaneously with the electrical connection of the liashlight circuit to the camera terminals of the ignition minal, an axially movable central terminal and an insulated bottom, a spring about the central terminal biasing the movable central terminal upwardly within the outer cylindrical terminal, an extension of the central terminal through the socket bottom of which the upper portion is electrically conductive and the lower portion is electrically non-conductive, a first conductor connecting one side of the capacitor to the conductive portion of the extension below the socket bottom, a first double throw switch of which the movable contact is mechanically connected to the non-conductive extension portion, a first fixed contact connected to one side of the capacitor and a second fixed contact connected to the other side of the capacitor, the switch movable contact engaging the first fixed contact when no flashbulb is in the socket and the second fixed contact when a flashbulb is inserted in the socket, a second conductor, a second single throw switch of which the movable contact is connected by the second conductor to the cylindrical terminal of the socket and the fixed contact of the single throw switch is connected to the movable contact of the first double throw switch, the movable contact and the fixed contact of thesecond switch being normally disengaged, a test lamp in series between the fixed contact of the second switch and the movable contact of the first switch, a third conductor connected to the other side of the capacitor, and the second fixed contact of the first switch, and a third switch selectively connecting the second and third conductors to fire a flashbulb in the socket on closure of the third switch.

2. A B-C flash circuit according to claim 1 in which the movable contact of the second switch is connected to one terminal of a pair of terminals adapted to be connected to at least one additional flashbulb socket, the other terminal of the pair being connected to the third conductor.

3. A B-C photoflash circuit according to claim 1 in which the magnitude of the resistor is such that with a flashbulb in the socket, upon closure of the third switch to engage its movable contact with its fixed contact, the current through the closed circuit is insuflicient to flash the bulb but sufficient to light the test lamp of which the brilliance is an indication of the condition of the battery.

4. A BeC photoflash circuit according to claim 1 in which a normally open fourth switch is serially connected between the battery and the capacitor in the charging circuit, the third switch and a portion of the second and third conductors are within a camera body while all the other elements of the photoflash circuit are external to the camera body, and means closing the fourth switch on connection of the photoflash circuit to the third switch in the camera body to limit drain on the battery to the period when the third switch is interconnected to the other elements of the photoflash circuit.

5. A B-C photofiash circuit according to claim l in which a housing contains all the elements of the circuit other than the third switch and portions of the second and third conductors, the third switch is mounted in the camera and has such portions of the third conductors in the form of a first rigid coaxial cable connected to its contacts, a bushing integral with a camera wall through which the first rigid coaxial cable extends, an external radial flange integral with the bushing, a locking member projecting from the housing having an apertured rotatable locking ring for receiving the bushing flange and locking the housing to the camera on rotation of the ring, the remaining portions ofthe second and third conductors being the locking ring and a spring biased metal rod extending coaxially through the locking member and insulated therefrom, the outer end of the rod being engaged only by the outer end of the central terminal insulated from the outer terminal and the rst coaxial cable when the housing is locked to the camera, a biasing spring against which the rod is axially displaced a predetermined distance into the housing on locking of the housing to the camera, a fourth switch having a first and a second formed member normally not engaging each other, the first formed member being connected to one side of the battery and having a free end, the second formed member being connected to one side of the condenser andv having a free end with an elongated intermediate portion and a transverse end portion, the inner end of the spring biased rod being connected to the intermediate portion, the intermediate portion of the secondformed member being spaced the predetermined distance from the free end of the first formed member to close the fourth switch on locking the housing to the camera, a pair. of conductive bushings of which the first is connected to the battery and the second to fthe locking ri-ng, an extension cord having one end adapted to engage the first coaxial cable and a pair of plug terminals at its other end adapted to be inserted into the pair of conductive bushings to make electrical contact therewith, the transverse portion of the second formed member being in the path of the one plug terminal inserted into the first conductive bushing to engage therewith on insertion to close the fourth switch.

6. A B-C photoflash attachment for cameras comprising a housing, a charging circuit within the housing including a battery, a resistor, a capacitor and a first switch in series, a discharge circuit including a flashbulb socket and a second switch in shunt of the capacitor, the flashbulb socket being mounted in a wall of the housing and the second switch being within the camera, and selective means for mechanically connecting the housing directly to the camera and simultaneously closing the first switch and connecting the second switch to the flashbulb socket, and for connecting the second switch to the socket and simultaneously closing the first switch when the housing is remote from the camera.

7. A B-C photoflash attachment for cameras accord- 'ing to claim 6 in which the first switch is normally open and consists of a first formed member and a second formed member of spring conductive material, the first formed member being connected to one side of the battery and having a free end, the second formed member being connected at one end to one side of the capacitor and having a freely movable elongated intermediate portion spaced a predetermined distance from the free end of the first formed member and a freely movable end portion, a pin of insulating material projecting from the housing at the junction region of the intermediate and free end portions of the second formed member to limit the movement of such intermediate and free end portions in one direction, a first coaxial cable connected to the terminals of the ignition switch and projecting through a wall of the camera, the means for mechanically and electrically connecting the housing to the camera comprising a bushing in the camera wall through which the first coaxial cable extends, a formed flange integral with the outer end of the bushing and extending radially outward and spaced from the camera wall, a hollow sleeve extending outwardly from a wall of the housing, a locking ring rotatable on the hollow sleeve and having a formed aperture at the face thereof adjacent to the formed flange of the bushing to receive the formed flange and lock the sleeve thereto on rotation of the locking ring a quarter turn a spring biased rod within the sleeve and slidable axially therein being adapted on such rotation of the locking ring on the flange bushing to engage its outer end to the outer end of the first coaxial cable, the coiled spring about the rod biasing the rod toward the first coaxial cable, the inner end of the rod being connected to the intermediate portion of the second formed member of the first switch, the spring biased rod on such locking being displaced the predetermined distance against the spring bias to close the intermediate portion of the second formed member upon the free end of the first formed member to close the first switch, a pair of spaced conductive bushings through a portion of the housing wall adjacent to that portion of the housing wall'l througha which the sleeve extends, the lirst of the pair of bushings being electrically connected to the first formed member of the rst switch andthe second of` the pair of bushings being electrically connected to the flashbulbv socket, and an extension cord having a plug with two terminals insertable into the pair of spaced bushings at one endA and a coaxial connector at its other end for attachment to the outer end of the first coaxial cable, the free end portion of the second formed member being in the path of one plug terminal on insertion into the first bushing of the pair of bushings to make electrical contact therewith to close the first switch and to dellect the free endv portion of the second 'formed member about the pin-vof insulating material and with such free end of the second formed member its intermediate portion in the direction to increase the spacing between such intermediate portion beyond the predetermined distance to resiliently maintain the conductive connection between the inserted plug and the end portion of the second formed member.

References Cited in the file of this patent UNITED STATES PATENTS