Abstract:
A strip of photographic film is moved relative to the photographic film cassette from which the strip extends. A rewinding apparatus can be selectably engaged or disengaged from the film spool of the photographic film cassette. The techniques can be used in cameras, including low-cost or disposable cameras.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims the benefit of priority from U.S. Provisional Application Serial No. 60/231,772, filed on Sep. 12, 2000. 
     
    
     
       BACKGROUND  
         [0002]    This invention relates to photographic cameras and more particularly to film cassette engagement and disengagement in connection with reloading/preloading the film in a camera.  
           [0003]    Disposable cameras provide a convenient and low cost way of taking pictures. A user does not have to purchase expensive and complicated photography equipment, and does not have to be an expert in photography to take pictures. After all exposures are taken, the camera is given to a photo shop or photo laboratory without the user having to remove the film. If the user wants to take more pictures, he simply has to buy another camera.  
           [0004]    Disposable cameras have disadvantages in that the casing of the camera is discarded, creating waste of materials and hazards to the environment. The inability to reuse the camera creates these disadvantages. Disposable cameras are not reusable because they are designed to be opened only by destroying the case. As a consequence, there is no way to reload the camera with film. Some disposable cameras have the ability to be rewound. However, there is a need for a disposable camera that is reusable. It would be desirable to have a camera in which new film could be reloaded and rewound, and a device that would be useable in such a camera to rewind and reload film.  
         SUMMARY  
         [0005]    An arrangement is disclosed which permits a user of a camera to cause the strip of film, which is attached to a film winding spool inside that photographic film cassette, to translate with respect to the photographic film cassette, e.g., to be rewound back within the photographic film cassette after having been extracted from same. An aspect of the arrangement includes an advance wheel which is rotatably secured within the camera and a claw arrangement which is attached to the advance wheel by virtue of rails on a top surface of the advance wheel passing through sleeves in the claw arrangement. The combination of the claw arrangement with the advance wheel is termed the advance wheel mechanism. The connection between the advance wheel and the claw arrangement prevents them from rotating with respect to one another, but allows the claw arrangement to move up and down along the rails. An uppermost limit to the distance the claw arrangement can move along the rails exists and prevents the advance wheel and claw arrangement from becoming separated. A resilient member tends to urge the claw arrangement upward along the rails, causing it to reach the uppermost limit of its vertical traverse when no obstruction exists to prevent such upward movement. As the arrangement is deployed within a camera, when the claw arrangement is at the upper limit of its vertical traverse, no rotatable engagement is possible between it and the film winding spool of the photographic film cassette. However, the user can selectably urge the claw arrangement down along the rails to a point where the rotatable engagement will occur. When the claw arrangement is in this position, the user can use the advance wheel mechanism to move the strip of photographic film in the rewind direction, i.e., back into the photographic film cassette.  
           [0006]    Another aspect of the arrangement includes means for automatically locking the advance wheel mechanism in its rotatably engaged position with respect to the film winding spool once the user moves the claw arrangement downward past a certain point in its vertical traverse. Yet another aspect of the invention prevents the user from unlocking the claw arrangement from its rotatably engaged position with respect to the film winding spool until the rear door of the camera is released, the lock is automatically released, and the large resilient member urges the claw arrangement back up to the uppermost limit of its vertical traverse. Still another aspect of the invention includes a cantilevered ratchet arm, engaged with knurling on the advance wheel, which prevents the user (once the claw arrangement mechanism is in its rotatably engaged and locked position with regard to the photographic film cassette) from using a pre-winding key attached to a pre-wound film take-up spool to move the strip of photographic film in the pre-wind (opposite to rewind) direction. A further aspect of the invention includes a preventer which prevents a user from rotating the pre-wound film take-up spool in any other direction than the pre-wind direction.  
           [0007]    In a related aspect of the invention, a method is disclosed which allows a user to move a strip of photographic film within a camera relative to the photographic film cassette from which the strip extends. An aspect of the method provides rewinding means for rotating the film winding spool of the photographic film cassette in the rewind direction. Another aspect of the method provides disengagement means which prevent rotatable engagement between the rewinding means and the film rewinding spool. Yet another aspect of the method provides engagement means for selectably establishing rotatabe engagment between the rewinding means and the film rewinding spool. A further aspect of the method involves using the disengagement means to prevent rotatable engagement between the rewinding means and the film rewinding spool while pre-winding the strip of photographic film out of the photographic film cassette and into a pre-wound film storage area. Yet another aspect of the present method involves utilizing the engagement means to establish rotatable engagement between the rewinding means and the film winding spool. Still another aspect of the present method involves and utilizing the rewinding means to rewind the strip of photographic film back into the photographic film cassette.  
           [0008]    Accordingly, the invention describes an arrangement and a method associated with a low cost and convenient camera which can be reused and reloaded each time all exposures of a film cassette are used. The invention also provides a mechanism to allow a user to rewind and reload film. The mechanism prevents a user from advancing film in a cassette until a prewinding process is complete. In addition, the invention prevents a user from rewinding or prewinding used film in the middle of the roll.  
           [0009]    The details of an embodiment both of the arrangement and of the method are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description, and drawings, and from the claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1A is an exposed rear view of a camera with an implementation of a film engagement and disengagement apparatus.  
         [0011]    [0011]FIG. 1B is an exposed top view of a camera with an implementation of a film engagement and disengagement apparatus.  
         [0012]    [0012]FIG. 2 is an exploded view of an implementation of the engagement and disengagement apparatus; FIG. 2A is a detail view of a portion of FIG. 2.  
         [0013]    [0013]FIG. 3A and FIG. 3B are top and side views, respectively, of a camera at a first point of the film cycle of the present invention, i.e., that point at which the camera is in its reset condition, after the rear door is released and the photographic film cassette is inserted in the camera, but prior to pre-winding of the film.  
         [0014]    [0014]FIG. 4A and FIG. 4B are top and side views, respectively, of a camera at a second point of the film cycle of the present invention, i.e., that point when the leader portion of the strip of photographic film is attached to the pre-wound film take-up spool, and the rear door is ready to be replaced.  
         [0015]    [0015]FIG. 5A and FIG. 5B are top and side views, respectively, of a camera at a third point of the film cycle of the present invention, i.e., that point when the rear door of the camera has been replaced and the camera is ready for pre-winding of the strip of photographic film.  
         [0016]    [0016]FIG. 6A and FIG. 6B are top and side views, respectively, of a camera at a fourth point of the film cycle of the present invention, i.e., the winding key is inserted into the rotation interface and rotated, thus rotating the pre-wound film take-up spool, and also pulling the strip of photographic film from the photographic film cassette, causing it to be wrapped around the pre-wound film take-up spool.  
         [0017]    [0017]FIG. 7A and FIG. 7B are top and side views, respectively, of a camera at a fifth point of the film cycle of the present invention, i.e., the strip of photographic film has been pre-wound, and the advance wheel knob is depressed, triggering the deployment of a locking component (knob stopper) which holds the advance wheel mechanism in rotatable engagement with the film winding spool of the photographic film cassette.  
         [0018]    [0018]FIG. 8A and FIG. 8B are top and side views, respectively, of a camera at a sixth point of the film cycle of the present invention, i.e., the point when photographs are taken and the strip of photographic film is gradually rewound back within the photographic film cassette.  
         [0019]    [0019]FIG. 9A and FIG. 9B are top and side views, respectively, of a camera at a seventh point of the film cycle of the present invention, i.e., the film has been fully exposed and rewound, and the rear door may be released (causing the camera to revert to the reset condition), and the photographic film cassette can be removed. 
     
    
     DETAILED DESCRIPTION  
       [0020]    Referring to FIG. 1A, an exposed rear view of a camera  100  is shown which includes an implementation of a film engagement and disengagement apparatus  105 . The apparatus  105  includes a top plate  202 , a knob stopper  204 , an advance wheel mechanism  203 , a sprocket mechanism  230  and pre-winding arrangement  250 . FIG. 1B is an exposed top view of the camera  100 .  
         [0021]    [0021]FIG. 2 and FIG. 2A illustrate an exploded view of an implementation of the film engagement and disengagement apparatus  105  shown in FIGS.  1 A- 1 B. A typical photographic film cassette  201  is shown with a film cassette housing  201   a , film winding spool  201   b , and strip of photographic film  201   c . The apparatus  105  includes the top plate  202 , having four knob stopper retention prongs  202   a  (two aligned prongs are shown, two opposing prongs are obscured), knob clearance hole  202   b , shaft spindle clearance hole  202   c , resilient member mounting post  202   d , top plate upper surface  202   e , and top plate lower surface  202   f . Counter dial  240  is shown with counter dial mechanical fastener  241  above its rotatable mounting location on top plate  202 . Counter dial knurling  240   a  is also shown. Knob stopper  204  is shown in FIG. 2A with two rearward facing knob stopper lateral surfaces  204   a  (one is indicated), knob stopper upper surface  204   b , knob stopper lower surface  204   c , knob stopper angled surface  204   d , and knob clearance hole  204   e.    
         [0022]    The components of advance wheel mechanism  203  are also indicated in FIG. 2, all of which are arranged around a common central axis. Advance wheel knob  205  is shown, with claw engagement rail  205   a , knob engagement rail sleeve  205   b , conical side surface  205   c , knob upper surface  205   d , knob lower surface  205   e , claw mounting fastener hole  205   f , and knob depression button  205   g . Advance wheel  206  is shown, with knob engagement rails  206   a  (four are shown), claw engagement rail clearance hole  206   b , claw retention projection  206   c  (shown in FIG. 3B), advance wheel upper surface  206   d , advance wheel lower surface  206   e , and advance wheel knurling  206   f . Advance wheel claw  207  is shown, with claw engagement rail hole  207   a , two film winding spool engagement teeth  207   b , film winding spool engagement surface  207   c , spiral-shaped rear portion  207   d  of teeth  207   b , claw upper surface  207   e , and claw lower surface  207   f . Large diameter resilient member  208 , small diameter resilient member  209 , and claw mounting fastener  210  are also shown.  
         [0023]    The components of sprocket mechanism  230  are also indicated in FIG. 2, all of which are arranged around a common central axis. Sprocket  231  is shown, with sprocket lower surface  231   a , sprocket upper surface  231   b , film engagement teeth  231   c , and shaft engagement hole  231   d . Shaft  232  is shown, with sprocket engagement post  232   a , sprocket engagement plate  232   b , ratchet plate engagement holes  232   c , shaft spindle  232   d , and counter dial engagement gear  232   e . Ratchet plate  233  is shown, with two shaft engagement tabs  233   a  and two cam engagement prongs  233   b . Cam plate  234  is shown, with cam engagement prong engagement channel  234   a , two cam engagement prong engagement teeth  234   b  (shown in FIG. 6A and FIG. 8A), top plate engagement face  234   c , and shaft spindle sleeve  234   d.    
         [0024]    The components of pre-winding arrangement  250  are also indicated in FIG. 2, all of which, with the exception of preventer  251 , are arranged around a common central axis which they share with pre-wound film take-up spool  242 . Bottom plate  252 , rotation interface  253  and winding key  260  are all shown. Winding key  260  is shown again above knob depression button  205   g.    
         [0025]    Top plate resilient member is shown in Detail  2 A of FIG. 2 mounted on resilient member mounting post  202   d.    
         [0026]    Referring to FIG. 3A and FIG. 3B, a first point is shown of a film cycle which includes the processes of loading film in the camera, pre-winding the film within the camera, exposing the film within the camera, and removing the exposed film from the camera, leaving it ready for insertion of a new unexposed photographic film cassette. At the first point, the camera is at the reset position. The rear door of the camera is released, there is no film inside the camera, and the counter dial may be set to indicate ‘S’, or if it indicates a different number, it can be moved to indicate ‘S’ by manual rotation until it stops at ‘S’. The knob stopper  204  remains in the open position by the force of top plate resilient member  211 , with rearward-facing knob stopper lateral projections  204   a  resting against their respective knob stopper retention prongs  202   a . Advance wheel knob  205  is kept in its pop-up position by the force of large resilient member  208  urging lower surface  205   e  of the advance wheel knob upward, with knob engagement rails  206   a  located within knob engagement rail sleeves  205   b . The advance wheel claw  207  is kept in its default low position by the force of small resilient member  209  urging claw upper surface  207   e  downward. Because claw upper surface  207   e  also rests against advance wheel lower surface  206   e , the knob and claw portion of advance wheel knob mechanism  203  is prevented from moving upward any more than what is shown in FIG. 3. Advance wheel claw  207  is fixed in a centered position against the advance wheel  206  by claw locating projection  206   c.    
         [0027]    Referring to FIG. 4A and FIG. 4B, a second point of the film cycle is shown. At the second point, an unexposed photographic film cassette  201  is inserted within the film cassette storage chamber of the open camera housing, a leader portion of strip  201   c  of photographic film is manually pulled from the film cassette housing  201   a , edge-located gear-engaging perforations  201   d  of strip  201   c  of photographic film are caused to be engaged with film engagement teeth  231   c  of sprocket  231 , and the end of the leader portion of the strip  201   c  of photographic film is attached to at least one film engagement hook  242   a  of the pre-wound film take-up spool  242 . Once this is done, the rear door of the camera housing can be replaced, thus completing the camera housing.  
         [0028]    Referring to FIG. 5A and FIG. 5B, a third point of the film cycle is shown. At the third point, the rear door of the camera housing is replaced, the photographic film cassette  201  is in place within the camera, and the camera is ready for pre-winding of the strip  201   c  of photographic film. The location of the advance wheel mechanism  203 , the knob and claw portion of which is maintained in the pop-up position by the force of large resilient member  208 , is unchanged. The knob stopper  204  is urged by the superior force of the rear door from its default rear position to a more forward position at which it presents an obstruction to the previously unobstructed downward path of the advance wheel knob  205 . More specifically, the upward-facing knob stopper angled surface  204   d  is located near or against the downward facing conical side surface  205   c  of the advance wheel knob  205 . FIG. 5A shows the advance wheel knob  205  obscuring the knob stopper angled surface  204   d , thus demonstrating the pop-up position of the advance wheel mechanism  203  occurring contemporaneously with the more forward position of the knob stopper  204 . Further describing the condition of the camera at the third point of the film cycle, the advance wheel claw  207  remains in its default upward position against the advance wheel  206 , and the film winding spool  201   b  of the photographic film cassette  201  remains unengaged.  
         [0029]    Referring to FIG. 6A and FIG. 6B, the fourth point of the film cycle is shown. At the fourth point, winding key  260  is inserted into the rotation interface  253  and rotated in the pre-wind direction, rotating the pre-wound film take-up spool  242 , pulling the strip  201   c  of photographic film from the film cassette housing  201   a , causing it to pass to the other side of the camera, and to be wound around the pre-wound film take-up spool  242 . Preventer  251  prevents a user from using the winding key  260  to rotate the pre-wound film take-up spool in the direction opposite from the pre-wind direction. Because gear-engaging perforations  201   d  are engaged with film engagement teeth  231   c  of sprocket  231 , the pre-winding movement of the strip of photographic film causes the sprocket to spin, which causes the ratchet plate  233 , attached to sprocket  231  by means of shaft engagement tabs  233   a , to spin in unison with the sprocket. However, in this direction of sprocket spin (i.e., pre-wind) the cam engagement prongs  233   b  of the ratchet plate skip past the teeth  234   b  of the cam plate  234  with which they are designed to engage in the opposite direction of sprocket spin (rewind). As a result, though the shaft spindle  232   d , attached to the sprocket by sprocket engagement post  232   a , is sleeved within the shaft spindle sleeving hole  234   d  of the cam plate  234 , and spins in unison with the sprocket, the cam plate is not subject to any appreciable torquing force from the ratchet plate and does not spin during pre-wind of the film. However, because the shaft spindle  232   d  does spin during pre-wind, the counter dial engagement gear  232   e  of the shaft spins as well, driving the counter dial  240  to spin, and the count of available exposures, indicated by numerals visible to the user as they pass under a viewing hole in the camera housing, to rise in proportion to the length of film removed from the film cassette housing  201   a . As such, if the photographic film cassette  201  holds sufficient film for  27  exposures, and the film is completely pre-wound, the numeral appearing through the viewing hole will be  27 ; if a complete pre-wind produces sufficient film for  24  exposures, the numeral appearing will be  24 , and so on.  
         [0030]    Referring to FIG. 7A and FIG. 7B, a fifth point of the film cycle is shown. The switch from the fourth point to the fifth point is to be undertaken after the user has completed pre-winding the film, and is accomplished by the user urging the advance wheel knob  205  downward so that the advance wheel claw  207  can engage the film winding spool  201   b  of the photographic film cassette  201 . The winding key  260  can be used to urge the advance wheel knob downward by the user holding the key upright, placing the small diameter end of the key against the center of the top surface of the knob depression button  205   g , and pushing downward on the winding key. Initially, this will cause the downward facing conical side surface  205   c  of the advance wheel knob  205  to press and slide against the knob stopper angled surface  204   d , which will cause the advance wheel mechanism  203  to tilt slightly forward, and the knob stopper to move rearward to the extent the rear door of the camera can flex to accommodate the rearward movement of the knob stopper  204 . Once the upper surface  205   d  of the advance wheel knob moves below the lower surface  204   c  of the knob stopper, the knob stopper will ‘snap’ forward by the force of the relaxing flex of the rear door to a position over the upper surface  205   d  of the knob stopper, and the slight forward tilt of the advance wheel mechanism  203  will be relieved, since the angled surface  204   d  of the knob stopper will no longer be in interference with the downward facing conical side surface  205   c  of the advance wheel knob. The large resilient member  208  is thus placed in a more compressed state. In this way the upper surface  205   d  of the knob stopper, which is biased toward its pop-up position by the force of large resilient member  208 , will be prevented from moving upward by the presence of the ‘ceiling’ now formed by the lower surface  204   c  of the knob stopper. At this point, the downward force applied to the knob depression button  205   g  can be removed, because the advance wheel claw will be held in proper position to engage the film winding spool  201   b  of the photographic film cassette. The advance wheel mechanism  203  itself will thus be locked in an engaged position with regard to the film winding spool  201   b  of the photographic film cassette  201 , a condition which will persist until such time as the knob stopper is allowed to move rearward (i.e., when the rear door of the camera housing is removed, which happens after the film is fully rewound). If for any reason (e.g., initial angular misalignment) the advance wheel claw  207  is not fully engaged with the film winding spool  201   b  of the photographic film cassette  201  immediately after the depression and downward-locking of the advance wheel knob  205 , it will become so engaged once the user begins to utilize the advance wheel to rewind the film. This gradual ‘seating’ of what may be an initially misaligned advance wheel claw occurs because a) the spring force of small resilient member  209  tends to force the advance wheel claw  207  downward along claw engagement rail  205   a  toward full engagement with the film winding spool  201   b , and b) the spiral-shaped rear portions  207   d  of the spindle engagement teeth  207   b  of the advance wheel claw  207  allow the advance wheel to slide along corresponding structure of the film winding spool  201   b  and gradually drop into its spindle-engaging position. FIG. 7A shows the upper surface  204   b  and angled surface  204   d  of the knob stopper  204  obscuring the upper surface  205   d  of the advance wheel knob, thus demonstrating the downward-locked position of the advance wheel mechanism  203 .  
         [0031]    It is noted that if, at a time just prior to the switch from the fourth point of the film cycle to the fifth point, the user has not yet pre-wound all of the available film out of the film cassette housing  201   a , stopping for example at a point when the counter dial indicated  24  available exposures although sufficient film for  36  exposures was in fact available, and the user then switches to the fifth point of the film cycle, the  12  exposures which were yet to be pre-wound out of the film cassette housing at that point will, in accordance with the present invention, remain thereafter within the housing, not to be removed unless for film development purposes after the photographic film cassette  201  is removed from the camera. This is because advance wheel claw  207 , from that point forward, will be engaged with the film winding spool  201   b  of the photographic film cassette  201 , and the advance wheel  206 , which would otherwise rotate with the advance wheel claw if the strip  201   c  of photographic film were to be pulled back out of the film cassette housing  201   a  by further winding of winding key  260 , is prevented from so rotating in the pre-wind direction by a cantilevered ratchet arm  750  which constantly engages the advance wheel knurling  206   f  and allows rotation in the rewind direction only. Such an arrangement prevents any portion of film, once exposed by a user, from being exposed again.  
         [0032]    Referring to FIG. 8A and FIG. 8B, the sixth point of the film cycle is shown. The camera  100  is now prepared for the user to begin taking photographs. At first, the user begins to turn the advance wheel  206  in the rewind direction, thus beginning the process of rewinding the strip  201   c  of photographic film back into the film cassette housing  201   a . Because the edge-located gear-engaging perforations  201   d  of the film are engaged with the film engagement teeth  23   1   c  of the sprocket  231 , the shaft spindle  232   d  will begin to turn the counter dial (not shown), and the ratchet plate  233  will engage the ratchet prong engagement teeth  234   b  of the cam plate  234 , beginning to turn it as well. As will be readily appreciated by those of skill in the art, mechanisms (not shown) within the camera driven by the cam plate  234  operate to a) lock the advance wheel before every exposure, b) trigger the displacement of the shutter (not shown) to expose the film, and c) release the advance wheel for further winding of the film after exposure. This pattern is repeated until the counter dial indicates (whether with an ‘S’ or some other appropriate indicator) that all the film is exposed and rewound back into the film cassette housing  201   a . The user will be prevented from accomplishing any further pre-wind of the film, whether by using the winding key  260  to turn the rotation interface  253  in the pre-wind direction, or by using any other method of turning the pre-wound film take-up spool  242 , because of the combination of a) the engagement of the film winding spool  201   c  of the photographic film cassette  201  by the advance wheel claw  207  (which will persist until the rear door is released from the camera housing), and b) the ratchet action of the cantilevered ratchet arm  750  of the top plate which constantly engages the knurling  206   f  of the advance wheel  206  and prevents the advance wheel from rotating in any other way than the rewind direction.  
         [0033]    Referring to FIG. 9, the seventh point of the film cycle is shown. The counter dial indicates with an ‘S’ that the film is fully exposed and rewound. At this point, the rear door may be released from the camera housing without risking unwanted exposure of the film. After the rear door is released, the knob stopper  204 , because it is no longer urged forward by the superior force created by the presence of the rear door, is once again urged rearward by the lesser force of the top plate resilient member  211 . This moves the knob stopper away from its obstructing ‘ceiling’ position relative to the advance wheel knob top surface  205   d , and the knob and claw portion of the advance wheel mechanism  203  is urged upward by the large resilient member  208 . The photographic film cassette  201  can be removed from the camera at this time and the film cycle described above can be begun again at the first point with a new roll of film.