Abstract:
A camera including a normally closed door moveable to be opened, and a sprocket wheel retractable from a film engageable position, is characterized in that an actuator is moveable simultaneously to move the door open and to retract the sprocket wheel from its film engageable position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Reference is made to commonly assigned application Ser. No. 08/898,096 entitled CAMERA WITH ACTUATOR FOR MOVING SPROCKET WHEEL TO FILM ENGAGING POSITION WHEN DOOR CLOSED and filed Jul. 22, 1997 now U.S. Pat. No. 5,799,220 in the name of Dennis R. Zander. 
     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 with an actuator for simultaneously opening a closed door and retracting a sprocket wheel from a film engageable position. 
     BACKGROUND OF THE INVENTION 
     Commonly assigned U.S. Pat. No. 5,493,358 issued Feb. 20, 1996 discloses a camera including a normally closed door moveable to be opened, and a sprocket wheel retractable from a film engageable position. When the door is opened, a return spring is allowed to urge a pivot a link bar on which the sprocket wheel is rotatably supported to the film engageable position. 
     THE CROSS-REFERENCED APPLICATION 
     The cross-referenced application discloses a camera comprising a door moveable to be closed, a sprocket wheel having respective teeth for entering successive spaced perforations in a filmstrip to engage the filmstrip and being moveable to a film engaging position for one of the teeth to enter one of the film perforations, and an actuator moveable to move the sprocket wheel to its film engaging position when the door is moved to be closed. The actuator has a compliant member which yields elastically when the actuator is moved to move the sprocket wheel to its film engaging position, but one of the teeth comes to rest against a limited section of the filmstrip between two of the film perforations rather than the tooth entering one of the perforations. Thus, the compliant member acts to prevent the tooth from perforating the limited section of the filmstrip. 
     SUMMARY OF THE INVENTION 
     A camera comprising a normally closed door moveable to be opened, and a sprocket wheel retractable from a film engageable position, is characterized in that: 
     an actuator is moveable simultaneously to move the door open and to retract the sprocket wheel from its film engageable position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a rear perspective view of a camera according to a preferred embodiment of the invention, showing a rear door for a cartridge receiving chamber closed; 
     FIG. 2 is a side elevation view of the camera as shown in FIG. 1; 
     FIG. 3 is a is a rear perspective view of the camera, showing the rear door opened; and 
     FIG. 4 is a side elevation view of the camera as shown in FIG. 3. 
    
    
     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. 1-4 partially show a camera 10 comprising a main body part or frame 12 and a front cover part 14. A combined rear and bottom cover part is not shown in order to be able to depict interior components of the camera 10. 
     The main body part 12 includes a cartridge receiving chamber 16 for a conventional 35 mm film cartridge 18 that has a filmstrip 20 with a protruding leader portion 22, a backframe opening 24 for exposing successive imaging areas of the filmstrip, a parallel pair of identical film rails 26 for supporting each of the imaging areas in a film exposure plane at the backframe opening, an exposed film take-up spool 28 rotatably supported in a take-up chamber 30, a manually rotatable thumbwheel 32 coaxially connected to the spool for being rotated in a film take-up direction (clockwise in FIG. 1) to similarly rotate the spool, and a sprocket wheel 34 having respective evenly spaced teeth 36 for entering successive similarly spaced perforations 38 in the filmstrip to drivingly engage the filmstrip. The thumbwheel 32 is drivingly connected to the sprocket wheel 34 via a gear and shaft train, which includes gears 40, 42 and 44, to cause rotation of the thumbwheel in the film take-up direction (clockwise in FIG. 1) to similarly rotate the sprocket wheel. The sprocket wheel 34 has a central hub 46 that protrudes through a slot 48 in the main body part 12 to be end-connected to a pivot arm 50 to rotatably support the sprocket wheel. The pivot arm 50 is pivotable about a shaft end 52 to move the sprocket wheel 34 between a film engaging position for one of the sprocket teeth 36 to enter one of the film perforations 38, as shown in FIGS. 1 and 2, and retracted from the film engaging position to separate the sprocket tooth from the film perforation, as shown in FIG. 3 and 4. 
     A rear door 54 is pivotally connected to the main body part 12 at a pivot pin 56 for opening movement to uncover the cartridge receiving chamber 16 and for closing movement to light-tightly cover the cartridge receiving chamber. A manual latching slide 58 for normally securing the rear door 54 closed in a well known way is translated to the right in FIG. 1, against the reverse urging of a return spring (not shown), to release the rear door, to permit the rear door to be opened. See FIG. 3. 
     An actuator slide 60 is supported at several fixed supports 62, 64 and 66 of the main body part 12 for translation to the left in FIGS. 1 and 2 and to the right in FIGS. 3 and 4. A helical tension spring 68 has its opposite ends connected to the main body part 12 and to the actuator slide 60 to urge the actuator slide to the left in FIGS. 1 and 2. A finger-like rigid projection 70 of the rear door 54 abuts a resilient (compliant) inclined cantilevered extension 72 of the actuator slide 60, when the latching slide 58 secures the rear door closed. The cantilevered extension 72 is less compliant than the tensile (pulling) force the spring 68 exerts on the actuator slide in FIGS. 1 and 2, to prevent the cantilevered extension from yielding elastically to the tensile force of the spring. 
     The sprocket hub 46 extends through an elongate opening 74 in the actuator slide 60 that is defined by a continuous cam profile 76. The cam profile 76 has a rigid inclined positioning edge 78 that is moved against the sprocket hub 46 to pivot the sprocket wheel 34 to its film engaging position in FIGS. 1 and 2, when the actuator slide 60 is translated to the right in FIGS. 3 and 4, and a rigid inclined retracting edge 80 that is moved against the sprocket hub to retract the sprocket wheel from its film engaging position, when the actuator slide 60 is translated to the left in FIGS. 1 and 2. A rigid terminal edge 82 of the cam profile 76 that is located adjacent the inclined positioning edge 78 longitudinally extends parallel to the two film rails 26 to support the sprocket hub 46 to hold the sprocket wheel 34 in the film engaging position, and a rigid terminal edge 84 of the cam profile that is located adjacent the inclined retracting edge 80 longitudinally extends parallel to the two film rails to support the sprocket hub to hold the sprocket wheel retracted from the film engaging position. 
     Operation 
     When the latching slide 58 is manually translated to the right in FIG. 1, contrary to the reverse urging of the return spring (not shown), to release the rear door, to permit the rear door to be opened, the helical tension spring 68 is free to automatically (spontaneously) translate the actuator slide 60 to the left in FIGS. 1 and 2. When the spring 68 translates the actuator slide 60 to the left in FIGS. 1 and 2, the cantilevered extension 72 of the actuator slide is pulled against the projection 70 of the rear door 54 to pivot the rear door open. See FIGS. 3 and 4. Concurrently, the inclined retracting edge 80 of the cam profile 76 is moved against the sprocket hub 46 to retract the sprocket wheel 34 from its film engaging position. Then, the terminal edge 84 of the cam profile 76 that is located adjacent the inclined retracting edge 80 supports the sprocket hub 46 to hold the sprocket wheel 34 retracted from the film engaging position. See FIGS. 3 and 4. 
     When the rear door 54 is manually closed, the projection 70 of the rear door is swung against the cantilevered extension 72 of the actuating slide 60 to translate the actuating slide to the right in FIGS. 1 and 2 contrary to the reverse urging of the spring 68. Concurrently, the inclined positioning edge 78 of the cam profile 76 is moved against the sprocket hub 46 to pivot the sprocket wheel 34 to its film engaging position. Then, the terminal edge 82 of the cam profile 76 that is located adjacent the inclined positioning edge 78 supports the sprocket hub 46 to hold the sprocket wheel 34 in the film engaging position. See FIGS. 1 and 2. 
     If the sprocket wheel 34 is pivoted towards its film engaging position, but one of the sprocket teeth 36 comes to rest against a narrow section of the filmstrip 20 between two of the film perforations 38 rather than the tooth entering one of the perforations, the cantilevered extension 72 of the actuator slide 60 will yield elastically in deference to the projection 70 of the rear door 54. This prevents the tooth from perforating the narrow section of the filmstrip. 
     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. front cover part 
     16. cartridge receiving chamber 
     18. film cartridge 
     20. filmstrip 
     22. protruding leader portion 
     24. backframe opening 
     26. pair of film rails 
     28. exposed film take-up spool 
     30. take-up chamber 
     32. thumbwheel 
     34. sprocket wheel 
     36. sprocket teeth 
     38. film perforations 
     40. gear 
     42. gear 
     44. gear 
     46. sprocket hub 
     48. slot 
     50. pivot arm 
     52. shaft end 
     54. rear door 
     56. pivot pin 
     58. latching slide 
     60. actuator slide 
     62. fixed support 
     64. fixed support 
     66. fixed support 
     68. helical tension spring 
     70. projection 
     72. inclined cantilevered extension 
     74. elongate opening 
     76. cam profile 
     78. inclined positioning edge 
     80. inclined retracting edge 
     82. terminal edge 
     84. terminal edge