Abstract:
A camera adapted to receive any one of a plurality of film loads having different film speeds includes a film speed sensing device for sensing the particular film speed of a film load in the camera, an aperture setting device adjustable to effect different-diameter film exposing apertures, a shaped memory alloy (abbreviated to SMA) wire which when subjected to electrical current for different durations corresponding to the respective film speeds of the film loads is heated to undergo corresponding shape changes to adjust the aperture setting device to the respective film exposing apertures, and a current supplying circuit connected to the SMA wire and to the film speed sensing device that subjects the SMA wire to electrical current for any one of the durations in accordance with the particular film speed of a film load in the camera.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Reference is made to commonly assigned copending application Ser. No. 09/758,810, entitled LENS DISPLACEMENT OR OTHER CONTROL USING SHAPED MEMORY ALLOY DRIVER and filed January 11, 2001 in the name of Timothy J. Fuss. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to the field of photography, and in particular to cameras. More specifically, the invention relates to a camera in which aperture adjustment for an objective lens is accomplished using a shaped memory alloy driver. 
     BACKGROUND OF THE INVENTION 
     Prior art U.S. Pat. No. 5,279,123 issued Jan. 18, 1994 mentions that shaped memory alloy (abbreviated to SMA) devices are well known in the art to undergo a martensitic (diffusionless) transition dependent upon the temperature applied to the SMA device. The SMA device when heated above its transition temperature undergoes a shape change to a memorized shape and when cooled below its transition temperature reverses the shape change from the memorized shape to an original shape. This change in shape can be used to provide mechanical work. 
     Often, as disclosed in prior art U.S. Pat. No. 5,459,544 issued Oct. 17, 1995, the SMA device is a fine metallic wire. When electrical current is applied to lead wires connected to opposite ends of the SMA wire, the SMA wire is heated to due to electrical resistance and it shrinks or contacts, i.e. recovers, to a memorized shape. When the electrical current is discontinued, the SMA wire cools to extend, i.e. deform, to an original shape. One application of the SMA wire to do mechanical work in U.S. Pat. No. 5,459,544 is a lens displacing mechanism for an objective lens, including an actuator pivotable in opposite directions to displace the objective lens in respective directions and an SMA wire which when heated contracts to its memorized shape to pivot the actuator forward to displace the objective lens forward and when cooled extends to its original shape to allow a return spring to pivot the actuator rearward to displace the objective lens rearward. The objective lens is displaced between two extreme positions, a close or near focus position and a far or infinity focus position, to change the actual distance between the lens and the film plane in a camera in order to adjust the image sharpness. Another application of the SMA wire to do mechanical work in U.S. Pat. No. 5,459,544 is an aperture adjustment mechanism, including an aperture blade which has a large diameter hole and a small diameter hole and which can be translated in opposite directions to move either one of the holes into optical alignment with the objective lens, a cantilever leaf spring that is connected to the aperture blade between the two holes and that can snap in opposite directions to alternative stable positions to translate the aperture blade in opposite directions, and a pair of SMA wires that are connected to the leaf spring and when alternately heated to contract to their memorized states urge the leaf spring to snap to its respective stable positions. 
     The Cross-Referenced Application 
     The cross-referenced application discloses a camera control mechanism comprising an actuator movable to adjust an adjustable component, such as for lens focusing or aperture adjustment, and a shaped memory alloy (abbreviated to SMA) wire which when heated contracts to a memorized shape to move the actuator to adjust the adjustable component. The SMA wire has opposite ends that are fixed in place and an intermediate movable portion between the opposite ends that directly contacts the actuator to move the actuator when the SMA wire is heated to contract. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a camera adapted to receive any one of a plurality of film loads having different film speeds comprises: 
     a film speed sensing device for sensing the particular film speed of a film load in the camera; 
     an aperture setting device adjustable to effect different-diameter film exposing apertures; 
     a shaped memory alloy (abbreviated to SMA) wire which when subjected to electrical current for different durations corresponding to the respective film speeds of the film loads is heated to undergo corresponding shape changes to adjust the aperture setting device to the respective film exposing apertures; and 
     a current supplying circuit connected to the SMA wire and to the film speed sensing device that subjects the SMA wire to electrical current for any one of the durations in accordance with the particular film speed of a film load in the camera. 
     According to another aspect of the invention, a method of adjusting an aperture setting device to effect different-diameter film exposing apertures in a camera adapted to receive any one of a plurality of film loads having different film speeds comprises: 
     sensing the particular film speed of a film load in the camera; and 
     subjecting a shaped memory alloy (abbreviated to SMA) wire to electrical current for different durations corresponding to the respective film speeds of the film loads, to heat the SMA wire to cause it to undergo corresponding shape changes and adjust the aperture setting device to the respective film exposing apertures in accordance with the particular film speed of a film load in the camera. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front exploded perspective view of a partial camera that accomplishes aperture adjustment using a shaped memory alloy (abbreviated to SMA) driver; 
     FIG. 2 is a front assembled perspective view of the partial camera; 
     FIG. 3 is a front exploded perspective view of an aperture setting device in the camera, showing an f/8 aperture setting for a film speed ISO 100 or 200; 
     FIG. 4 is a is a front elevation view of the aperture setting device as in FIG. 3; 
     FIG. 5 is a is a front exploded perspective view of the aperture setting device, showing an f/11 aperture setting for a film speed ISO 400; 
     FIG. 6 is a is a front elevation view of the aperture setting device as in FIG. 5; 
     FIG. 7 is a is a front exploded perspective view of the aperture setting device, showing an f/5.6 aperture setting for a film speed ISO 800; and 
     FIG. 8 is a is a front elevation view of an aperture setting device as in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is disclosed as being embodied preferably in a camera. Because the features of a camera are generally known, the description which follows is directed in particular only to those elements forming part of or cooperating directly with the disclosed embodiment. It is to be understood, however, that other elements may take various forms known to a person of ordinary skill in the art. 
     Referring now to the drawings, FIGS. 1 and 2 show a partial camera  10  including a main body part  12  that has a cartridge receiving chamber  14  for a standard 35 mm film cartridge  16 . and has an exposed film roll chamber  18 . As is known, the film cartridge  16  has the DX system of encoding film speed (ISO). The film speed is encoded by imprinting a pattern of conductive and non-conductive patches on an outer wall of the film cartridge  16 . For example, the patches  20 ,  22  and  24 , depending on whether they are conductive or non-conductive, indicate various film speeds. In FIGS. 1-4, the patch  20  is conductive and the patches  22  and  24  are non-conductive to indicate ISO 400. In FIGS. 5 and 6, the patches  20  and  22  are conductive and the patch  24  is non-conductive to indicate ISO 800. In FIGS. 7 and 8, the patches  20 ,  22  and  24  are conductive to indicate ISO 100 or 200. In each instance, the patch  20  is conductive as a common or ground patch. A rear door  26  is pivotally connected to the main body part  12  to be closed to light-tightly seal the cartridge receiving chamber  14  and to be opened to load/unload the film cartridge  16  into/from the chamber. 
     A film speed sensing device in the form of three separate film speed sensors  28 ,  30  and  32  are mounted on the main body part to project into the cartridge receiving chamber  14  at individual openings  34 ,  36  and  38  in the chamber. See FIG.  1 . The film speed sensors  28 ,  30  and  32  make electrical contact with the patches  20 ,  22  and  24  on the film cartridge  16  in the cartridge receiving chamber  14  and sense whether the patches  30  and  32  are conductive or non-conductive. 
     A fixed mount plate  40  is mounted on the main body part  12  over a pivotable shutter blade  42  and a pivotable aperture blade  44 . A fixed current-supplying circuit board  46 , a pivotable actuator lever  48  and a fixed trace circuit board  50  are on the main body part  12 . See FIGS. 1 and 2. The mount plate  40  has a recess  52  that contains an objective lens (not shown) and has an f/5.6 aperture  54 . The shutter blade  42  is pivotally supported on the mount plate  40  at a pivot hole  56  in the shutter blade for closing and opening movements to normally cover and momentarily uncover the f/5.6 aperture  54 . A torsion return spring (not shown) urges the shutter blade  42  closed to maintain the f/5.6 aperture  54  covered. The aperture blade  44  has an f/8 aperture  58  and an f/11 aperture  60 , and is pivotally supported on the mount plate  40  at a pivot hole  62  in the aperture blade. By comparison, the f/5.6 aperture  54  is the largest diameter hole, the f/11 aperture  60  is the smallest diameter hole, and the f/8 aperture  58  is a mid-diameter hole. The actuator lever  48  is pivotally supported on the main body part  12  via a post  64  on the main body part that projects through a pivot hole  66  in the actuator lever. An actuator pin  68  on the actuator lever  48  projects through a slot  70  in the aperture blade  44  to pivot the aperture blade clockwise in FIG. 1 when the actuator lever is pivoted counter-clockwise and to pivot the aperture blade counter-clockwise in FIG. 1 when the actuator lever is pivoted clockwise. A torsion return spring  71  at a center post  72  on the actuator lever  48  urges the actuator lever clockwise in FIGS. 1-4 to, in turn, pivot the aperture blade  44  counter-clockwise to set the f/8 aperture  58  in the aperture blade in optical alignment with the f/5.6 aperture  54  in the mount plate  40 . This effects a f/8 film-exposing aperture in FIGS. 1-4, which is a default aperture setting. If the actuator lever  48  is pivoted counter-clockwise (contrary to the urging of the torsion return spring  71 ) from its f/8 aperture setting as in FIGS. 5 and 6, the aperture blade  44  will be pivoted clockwise to set the f/11 aperture  60  in the aperture blade in optical alignment with the f/5.6 aperture  54  in the mount plate  40 . This effects a f/11 film-exposing aperture in FIGS. 5 and 6, which is a non-default aperture setting. If the actuator lever  48  is pivoted counter-clockwise (contrary to the urging of the torsion return spring  71 ) from its f/8 aperture setting as in FIGS. 7 and 8, the aperture blade  44  will be pivoted clockwise to be completely removed from the f/5.6 aperture  54  in the mount plate  40 . This effects a f/5.6 film-exposing aperture as in FIGS. 5 and 6, which is a non-default aperture setting. Thus, the aperture blade  44  and the actuator lever  48  act as an aperture setting device. 
     A shaped memory alloy (abbreviated to SMA) wire  74  has opposite ends  76  and  78  that are fixed on the current supplying circuit board  46  and an intermediate movable portion  80  between the opposite ends. The intermediate movable portion  80  of the SMA wire  74  extends partially around a catch pin  82  on the actuator lever  48  to longitudinally tension the SMA wire via the torsion return spring  71  for the actuator lever. See FIGS. 3-8. The wire end  76  is connected to the positive end  84  of a battery  86 , and the negative end  88  of the battery is connected to the film speed sensor  28  for the conductive patch  20  on the film cartridge  16 . A current limiting resistor  90  is located between the wire end  76  and the positive end  82  of the battery  86 . The wire end  78  is connected to a common or ground trace (fixed electrical contact)  91  on the trace circuit board  50 . 
     The trace circuit board  50 , in addition to the common trace  91 , has a f/5.6 trace (fixed electrical contact)  92  connected to the film speed sensor  32  for the conductive/non-conductive patch  24  on the film cartridge, and a f/11 trace (fixed electrical contact)  94  connected to the film speed sensor  30  for the conductive/non-conductive patch  22  on the film cartridge. See FIGS. 3-8. 
     The actuator lever  48  includes a switch device  96  that is affixed to the actuator lever for pivotal movement with the actuator lever and that has a pair of parallel common or ground switch elements  98  for making electrical contact with the common trace  91  on the trace circuit board  50  as in FIGS. 3-8, has a bifurcated f/5.6 switch element  100  for making electrical contact with the f/5.6 trace  92  on the trace circuit board as in FIGS.  3 - 8 ,. and has a bifurcated f/11 switch element  102  for making electrical contact with the f/11 trace  94  on the trace circuit board as in FIGS. 3-6. 
     A retainer  104  has an f/8 notch  106 , an f/11 notch  108  and an f/5.6 notch  110  that serve to alternatively engage with a finger  112  of the actuator lever  48  to hold the actuator in anyone of three positions as shown in FIGS. 4,  6  and  8 . The retainer  104  is supported on the main body part  12  for translation forward and rearward via a pair of parallel pin-in-slot connections  114 . See FIGS. 1 and 2. When the rear door  26  is closed, a push tab  116  on the rear door translates the retainer  104  forward to permit the retainer to engage with the finger  112  of the actuator lever  48 . When the rear door  26  is opened, a helical compression return spring (not shown) translates the retainer  104  rearward out of engagement with the finger  112 . 
     Operation 
     FIGS.  3  and  4 : 
     FIGS. 3 and 4 show the situation when the film cartridge  16  in the cartridge receiving chamber  14  has its respective patches  20 ,  22  and  24  conductive, non-conductive and non-conductive, the finger  112  of the actuator lever  48  is engaged with the f/8 notch  106  in the retainer  104 , the f/8 aperture  58  in the aperture blade  44  is in optical alignment with the f/5.6 aperture  54  in the mount plate  40  to effect a f/8 film-exposing aperture, the pair of common switch elements  98  of the switch device  96  make electrical contact with the common trace  91  on the trace circuit board  50 , the bifurcated f/5.6 switch element  100  of the switch device makes electrical contact with the f/5.6 trace  92  on the trace circuit board, and the bifurcated f/11 switch element  102  of the switch device makes electrical contact with the f/11 trace  94  on the trace circuit board. 
     Since the patches  22  and  24  of the film cartridge  16  are each non-conductive, the application of electrical current to the SMA wire  74  is prevented. Thus, the f/8 film-exposing aperture remains. 
     FIGS.  5  and  6 : 
     If conversely the film cartridge  16  in the cartridge receiving chamber  14  has its patches  20  and  22  each conductive (the patch  24  is non-conductive), electrical current is applied to the SMA wire  74 . The SMA wire  74  then is heated above its transition temperature, which causes it to contract in contact with the catch pin  82  on the actuator lever  48 . As a result, the actuator lever  48  is pivoted counter-clockwise in FIGS. 5 and 6 to pivot the aperture blade  44  clockwise to change the f/8 aperture  58  in the aperture blade from being in optical alignment with the f/5.6 aperture  54  in the mount plate  40  to the f/11 aperture  60  being in optical alignment with the f/5.6 aperture, to effect a f/11 film-exposing aperture, and to swing the finger  112  of the actuator lever  48  from being in the f/8 notch  106  in the retainer  104  to being in the f/11 notch  108  in the retainer, to retain the f/11 film-exposing aperture. As the finger  112  begins to enter the f/11 notch  108 , the bifurcated f/11 switch element  102  of the switch device  96  (which is pivoted with the actuator lever  48 ) separates from the f/11 trace  94  on the trace circuit board  50  to discontinue the application of electrical current to the SMA wire  74 . This allows the SMA wire  74  to begin to cool to extend. The pair of common switch elements  98  of the switch device  96  continue to make electrical contact with the common trace  91  on the trace circuit board  50 , and the bifurcated f/5.6 switch element  100  of the switch device continues to make electrical contact with the f/5.6 trace  92  on the trace circuit board. 
     FIGS.  7  and  8 : 
     If conversely the film cartridge  16  in the cartridge receiving chamber  14  has its patches  20  and  24  each conductive, electrical current is applied to the SMA wire  74 . The SMA wire  74  then is heated above its transition temperature, which causes it to contract in contact with the catch pin  82  on the actuator lever  48 . As a result, the actuator lever  48  is pivoted counter-clockwise in FIGS. 7 and 8 to pivot the aperture blade  44  clockwise to change the f/8 aperture  58  in the aperture blade from being in optical alignment with the f/5.6 aperture  54  in the mount plate  40  to the aperture blade being completely removed from the f/5.6 aperture in the mount plate, to effect a f/5.6 film-exposing aperture, and to swing the finger  112  of the actuator lever  48  from being in the f/8 notch  106  in the retainer  104  to being in the f/5.6  110  in the retainer, to retain the f/5.6 exposing aperture. As the finger  112  begins to enter the f/5.6 notch  110 , the bifurcated f/5.6 switch element  100  of the switch device  96  (which is pivoted with the actuator lever  48 ) separates from the f/5.6 trace  92  on the trace circuit board  50  to discontinue the application of electrical current to the SMA wire  74 . This allows the SMA wire  74  to begin to cool to extend. The pair of common switch elements  98  of the switch device  96  continue to make electrical contact with the common trace  91  on the trace circuit board  50 . 
     The time it takes for the finger  112  of the actuator lever  48  to swing from being in the f/ 8  notch  106  in the retainer  104  to being in the f/5.6 notch  110  in the retainer as in FIGS. 7 and 8 is longer than the time it takes for the finger to swing from being in the f/8 notch to being in the f/11 notch as in FIGS. 5 and 6. Thus, the application of electrical current to the SMA wire  74  must be longer in the first instance. That is why the bifurcated f/5.6 switch element  100  of the switch device  96  (which is pivoted with the actuator lever  48 ) separates from the f/5.6 trace  92  on the trace circuit board  50  only in FIGS. 7 and 8. 
     When the rear door  26  is opened in FIGS. 5-8, the helical compression return spring (not shown) translates the retainer  104  rearward to disengage the f/11 notch  108  in the retainer from the finger  112  of the actuator lever  48  in FIGS. 5 and 6 or to disengage the f/5.6 notch  110  in the retainer from the finger in FIGS. 7 and 8. Then, the torsion return spring  71  pivots the actuator lever  48  clockwise in FIGS. 5-8 to return the aperture blade  44  counter-clockwise to re-set the f/8 aperture  58  in the aperture blade in optical alignment with the f/5.6 aperture  54  in the mount plate  40 . This re-establishes the default aperture setting, i.e. the f/8 film-exposing aperture. 
     The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention. 
     PARTS LIST 
       10 . camera 
       12 . main body part 
       14 . cartridge receiving chamber 
       16 . film cartridge 
       18 . exposed film roll chamber 
       20 . patch 
       22 . patch 
       24 . patch 
       26 . rear door 
       28 . film speed sensor 
       30 . film speed sensor 
       32 . film speed sensor 
       34 . opening 
       36 . opening 
       38 . opening 
       40 . mount plate 
       42 . shutter blade 
       44 . aperture blade 
       46 . circuit board 
       48 . actuator lever 
       50 . circuit board 
       52 . recess 
       54 . f/5.6 aperture 
       56 . pivot hole 
       58 . f/8 aperture 
       60 . f/11 aperture 
       62 . pivot hole 
       64 . post 
       66 . pivot hole 
       68 . actuator Pin 
       70 . slot 
       71 . return spring 
       72 . center post 
       74 . SMA wire 
       76 . wire end 
       78 . wire end 
       80 . intermediate wire portion 
       82 . catch pin 
       84 . positive end 
       86 . battery 
       88 . negative end 
       90 . current limiting resistor 
       91 . common trace 
       92 . f/5.6 trace 
       94 . f/11 trace 
       96 . switch device 
       98 . common switch elements 
       100 . f/5.6 switch element 
       102 . f/11 switch element 
       104 . retainer 
       106 . f/8 notch 
       108 . f/11 notch 
       110 . f/5.6 notch 
       112 . finger 
       114 . pin-in-slot connection 
       116 . push tab