Abstract:
A normally closed shutter in a camera has at least one blade that is moved to open and close the shutter. A movable blade-driver in the camera has a supporting connection with a fixed support to support the blade-driver for movement, and has a driving connection with the shutter to drive at least the one blade to open and close the shutter when the driver is moved. A fixed blocking ramp in the way of the blade-driver stops the blade-driver once the blade-driver has moved to drive at least the one blade to close the shutter. The fixed ramp is inclined to urge or cam the blade-driver to create a high friction-type force at the supporting connection that impedes movement of the blade-driver to drive at least the one blade to re-open the shutter, whereby the shutter is prevented from being reopened unintentionally.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     Reference is made to commonly assigned, co-pending application Ser. No. ______ (Docket No. 86110RLW), filed Oct.  25 ,  2004 , entitled SYNCHRONIZING SHUTTER AND FLASH IN CAMERA, in the name of Wayne E. Stiehler.  
         [0002]     Reference is made to commonly assigned, co-pending application Ser. No. ______ (Docket No. 86111RLW), filed Oct.  25 ,  2004 , entitled DRIVER FOR OPENING AND CLOSING DUAL-BLADE SHUTTER ADAPTED TO BE RESET WITHOUT RE-OPENING SHUTTER, in the name(s) of Robert Gordon Hills, Michael L. Wirt, and Wayne E. Stiehler.  
         [0003]     Reference is made to commonly assigned, co-pending application Ser. No. ______ (Docket No. 86114RLW), filed concurrently herewith, entitled SHUTTER-OPENING/CLOSING AND SHUTTER-FLASH SYNCHRONIZATION DRIVER FOR DUAL-BLADE SHUTTER IN CAMERA, in the name of Wayne E. Stiehler. 
     
    
     FIELD OF THE INVENTION  
       [0004]     The invention relates generally to the field of photography and in particular to single-blade and multi-blade shutters in cameras. More specifically, the invention relates to preventing undesirable shutter-rebound or shutter-bounce in a camera that can cause unintended shutter-reopening to re-expose an exposed film frame.  
       BACKGROUND OF THE INVENTION  
       [0005]     Practically every film camera available today has a single-blade or multi-blade shutter. Generally speaking, the shutter opens to uncover an exposure aperture in order to permit ambient light reflected from a subject being photographed to reach a film frame behind the exposure aperture. Then, the shutter closes to recover the exposure aperture in order to end the exposure interval.  
       Single-Blade Shutters  
       [0006]     Typically, inexpensive cameras such as disposable single-use or one-time-use cameras have a single-blade shutter. The shutter blade pivots open and closed to uncover and recover the exposure aperture. To take a picture as in Patent Application Publication U.S. 2003/0118331 A1 published Jun. 26, 2003, a shutter release button is manually depressed. This unlatches a high energy lever which is pivoted via a high energy spring to impact against (strike) a strike tab upstanding on the shutter blade. The shutter blade in turn is pivoted open to uncover the exposure aperture. Then, once the high energy lever is pivoted beyond the strike tab, a return spring pivots the shutter blade closed to re-cover the exposure aperture.  
       Dual-Blade Center-Opening Shutters  
       [0007]     More complex than a single-blade shutter is a dual-blade center-opening shutter. A dual-blade center-opening shutter is one in which a pair of blades pivot open in opposite directions away from one other to uncover the exposure aperture and return to an overlapping closed relation to re-cover the exposure aperture. As in U.S. Pat. No. 5,136,324 issued Aug. 4, 1992, U.S. Pat. No. No. 5,258,797 issued Nov. 2, 1993, and U.S. Pat. No. 5,721,995 issued Feb. 24, 1998, individual fixed pivot-support posts project into respective pivot holes in the two blades, and a rotatable or pivotable shutter driver for opening and closing the two blades projects into respective overlapping slots in the two blades. Pivoting of the shutter driver in one direction within the overlapping slots pivots the two blades about the pivot-support posts to open, and pivoting of the shutter driver in an opposite direction within the overlapping slots pivots the two blades about the pivot-support posts to close.  
       The Problem of Shutter-Rebounding  
       [0008]     A shutter-rebound or shutter-bounce phenomenon can occur when closing the single-blade or dual-blade shutter. For example, during closing one or more of the blades may rebound or bounce off a fixed stop with sufficient force to partially reopen the shutter. Partially reopening the shutter can re-expose the last-exposed film frame.  
         [0009]     Prior art U.S. Pat. No. 6,554,502 B2 issued Apr. 29, 2003 purports to prevent shutter-rebound in a dual-blade center-opening shutter by adding a fixed inclined surface in the closing region of the blades. During shutter-closing, the speed of movement of the blades is reduced by the frictional drag of the inclined surface to prevent shutter-rebound.  
       The Cross-Referenced Application  
       [0010]     The cross-referenced application discloses a camera that has a single-piece shutter-opening/closing and shutter-flash synchronization driver that translates in one direction to pivot a pair of shutter blades away from one another and simultaneously push a movable switch contact of a normally open shutter-flash synchronization switch to close the switch. Then, the movable switch contact is spring-urged to move the switch contact to reopen the shutter-flash synchronization switch and push the single-piece driver in a reverse direction to move the blades towards one another.  
       SUMMARY OF THE INVENTION  
       [0011]     According to one aspect of the invention a camera comprises:  
         [0012]     a normally closed shutter having at least one blade that is moved to open and close the shutter;  
         [0013]     a movable driver having a supporting connection with a fixed object to support the driver to move, and having a driving connection with the shutter that drives at least the one blade to open and close the shutter when the driver is moved; and  
         [0014]     a fixed stop for the driver having a blocking face in the way of the driver to stop the driver once the driver has moved to drive at least the one blade to close the shutter, and being oriented to urge the driver to create a friction-type force at the supporting connection that impedes the driver to move to drive at least the one blade to re-open the shutter, whereby the shutter is prevented from being reopened unintentionally.  
         [0015]     According to another aspect of the invention camera capable of preventing shutter-bounce involving a normally closed shutter having at least one blade that is moved to open and close said shutter, comprises:  
         [0016]     means for moving a blade-drive post coupled with at least said one blade along a fixed support slot to move at least said one blade open and closed; and  
         [0017]     means for creating a friction-type relation between said blade-drive post and a peripheral edge of said fixed support slot to impede said blade-drive post from moving along said slot to move at least said one blade to reopen said shutter, whereby shutter-bounce is prevented. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is an exploded perspective view of a flash camera including a shutter-opening/closing and shutter-flash synchronization driver for a dual-blade center-opening shutter and a shutter-flash synchronization switch, and a fixed ramp for preventing shutter-rebound or shutter-bounce according to a preferred embodiment of the invention;  
         [0019]      FIG. 2  is an exploded perspective view of the driver, the dual-blade shutter, and the shutter-flash synchronization switch;  
         [0020]      FIG. 3  is an assembled perspective view of the driver, the dual-blade shutter, and the shutter-flash synchronization switch depicted in  FIG. 2 , showing the shutter closed and the switch open;  
         [0021]      FIG. 4  is a front elevation view similar to  FIG. 3 ;  
         [0022]      FIG. 5  is a top plan view similar to  FIG. 3   
         [0023]      FIG. 6  is an assembled perspective view of the driver, the dual-blade shutter, and the shutter-flash synchronization switch depicted in  FIG. 2 , showing the shutter open and the switch closed  
         [0024]      FIG. 7  is a front elevation view similar to  FIG. 6 ;  
         [0025]      FIG. 8  is a top plan view similar to  FIG. 6   
         [0026]      FIG. 9  is an assembled perspective view of the flash camera depicted in  FIG. 1 , showing the shutter open and the switch closed; and  
         [0027]      FIG. 10  is an assembled perspective view of the flash camera depicted in  FIG. 1 , showing the shutter closed and the switch open, and the fixed ramp preventing shutter-rebound or shutter-bounce.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     The invention is disclosed as preferably being embodied in a one-time-use flash camera. Since the elements of a one-time-use flash camera are generally known, the description which follows is directed mostly to those elements forming part of or cooperating with the invention. It is understood that those elements not disclosed may take various forms known to persons of ordinary skill in the camera arts.  
         [0029]     Referring now to the drawings and in particular to  FIGS. 1, 9  and  10 , there is shown a partially depicted one-time-use camera  10  including a main body part  12 , an electronic flash  14 , a dual-blade center-opening shutter  16 , a normally shutter-flash synchronization switch  18  that is closed to synchronize shutter-opening and flash-firing, an L-shaped driver or slider  20  for opening an closing the dual-blade shutter and for closing the shutter-flash synchronization switch, and a face plate  22 .  
         [0030]     As shown in  FIGS. 1, 9  and  10 , a fixed round pivot-support post  24  on the main body part  12  projects forward into a round pivot hole  26  in a first shutter blade  28  of the dual-blade center-opening shutter  16 , and a fixed round pivot-support post  30  on the main body part projects forward into a round pivot hole  32  in a second shutter blade  34  of the dual-blade shutter. The first and second shutter blades  28  and  38  are thin, and are plastic to be electrically non-conductive. The pivot-support posts  24  and  30  support the first and second shutter blades  28  and  34  for opening (parallel-axis) movement away from one another, i.e. clockwise and counter clockwise about the pivot-support posts in  FIGS. 6, 7  and  10 , to uncover a rectangular exposure aperture  36  in the main body part  12 . Also, the pivot-support posts  24  and  30  support the first and second blades  28  and  34  for return or reverse closing (parallel-axis) movement towards one another, i.e. counterclockwise and clockwise about the pivot-support posts in  FIGS. 3, 4  and  9 , to recover the exposure aperture  36 .  
         [0031]     When the first and second blades  28  and  34  of the dual-blade center-opening shutter  16  are moved away from one another to uncover the exposure aperture  36 , they form a substantially rectangular center-opening  38  over the exposure aperture. As shown in  FIGS. 6 and 7 , the center-opening  38  has a center-point  40  that is aligned with a center-line  42  of the exposure aperture  36 . As is known in the prior art, the center-line  42  of the exposure aperture  36  is coincident with an optical axis of a picture-taking lens (not shown). The pivot-support posts  24  and  30  are arranged relative one another and the center-point  40  so that, if a diagonal straight-line  44  is drawn through two opposite corners  46  and  48  of the center-opening  38 , the diagonal straight-line would intersect the center-point and the pivot-support posts. In  FIGS. 6 and 7 , the corners  46  and  48  are located upper-right and lower-left.  
         [0032]     As shown in  FIGS. 1, 9  and  10 , the electronic flash  14  has a flash circuit board  50  for flash-firing when the shutter-flash synchronization switch  18  is closed. The shutter-flash synchronization switch  18  is part of a flash-firing circuit on the flash circuit board  50  and includes a leaf-spring positive switch contact  52  and a movable negative switch contact  54 . A fixed round pivot-support post  56  on the main body part  12  projects upward into a round pivot hole  58  in the movable switch contact  54  to support the movable switch contact for pivotable movement, i.e. counterclockwise about the pivot-support post in  FIGS. 6-8  and  9 , against the leaf-spring switch contact  52  to close the shutter-flash synchronization switch  18 , and for return or reverse pivotable movement, i.e. clockwise about the pivot-support post in  FIGS. 3-5  and  10 , away from the leaf-spring switch contact to reopen the shutter-flash synchronization switch. A metal helical-tension return spring  60  has opposite ends conductively interconnecting the movable switch contact  54  and a fixed thin metal strip  62  mounted on the main body part  12 . The return spring  60  urges or biases the movable switch contact  54  away from the leaf-spring switch contact  52  to separate the movable switch contact from the leaf-spring switch contact. The metal strip  62  has one end  64  that protrudes into a battery chamber  66  in the main body part  12  to serve as a negative battery contact. A helical compression spring  68  conductively connected to the flash circuit board  50  protrudes into the battery chamber  66  to serve as a positive battery contact.  
         [0033]     The L-shaped driver or slider  20  for opening and closing the dual-blade shutter  16  and for closing the shutter-flash synchronization switch  18  is a single-piece plastic construction and has a pair of substantially right-angle horizontal and vertical driver legs  70  and  72  that essential provide the L-shape. As shown in  FIGS. 1 and 2 , the horizontal driver leg  70  has a fixed round blade-drive post  74  that protrudes forward through a elongate drive slot  76  in the first shutter blade  28  and into a straight translation-support slot  78  in the face plate  22 , and the vertical driver leg  72  has a fixed round blade-drive post  80  that protrudes forward through an elongate drive slot  82  in the second shutter blade  34  and into a straight translation-support slot  84  in the face plate. The translation-support slots  78  and  84  in the face plate  22  support the L-shaped driver  20  for translation to advance the L-shaped driver in a single forward direction  86 , to cause the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  away from one another, i.e. clockwise and counter clockwise about the pivot-support posts  24  and  30  in  FIGS. 6, 7  and  10 , to uncover the exposure aperture  36 . Also, the translation support slots  78  and  84  support the L-shaped driver  20  for translation to return the L-shaped driver in a single reverse direction  88 , to cause the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  towards one another, i.e. counterclockwise and clockwise about the pivot-support posts in  FIGS. 3, 4  and  9 , to recover the exposure aperture  36 . Thus, the blade-drive post  74  in the drive slot  76  and the blade-drive post  80  in the drive slot  82  are post-in-slot driving connections, and the blade-drive post  74  in the translation-support slot  78  and the blade-drive post  80  in the in the translation-support slot  84  are post-in-slot supporting connections.  
         [0034]     When the L-shaped driver  20  is translated in the single forward direction  86 , an upstanding switch drive finger  90  on the horizontal driver leg  70  pushes against the movable switch contact  54  (in opposition to the urging of the return spring  60 ) to pivot the movable switch contact, i.e. counterclockwise about the pivot-support post  56  in  FIGS. 6-9 , against the leaf-spring switch contact  52  to close the shutter-flash synchronization switch  18 . The shutter-flash synchronization switch  18  is closed at the same time that the blade-drive posts  74  and  80  pivot the first and second shutter blades  28  and  34  away from one another to uncover the exposure aperture  36 .  
         [0035]     Since the return spring  60  urges or biases the movable switch contact  54  to pivot away from the leaf-spring switch contact  52 , i.e. clockwise about the pivot-support post  56  in  FIGS. 3-5  and  10 , to re-close the shutter-flash synchronization switch  18 , the return spring pulls the movable switch contact continuously against the switch drive finger  90 . This allows the movable switch contact  54 , will be described below, to push against the switch drive finger  90  in order for the movable switch contact to translate the L-shaped driver  20  in the single reverse direction  88 , to cause the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  towards one another to recover the exposure aperture  36 .  
         [0036]     The face plate  22  is mounted on the main body part  12  and has a rectangular plate opening  92  that is aligned with the exposure aperture  36 . As depicted in  FIG. 1 , the face plate  22  partially covers the first and second shutter blades  28  and  34 .  
       Shutter-Opening/Closing and Shutter-Flash Synchronization  
       [0037]     A fixed round pivot-support post  94  on the main body part  10  projects upward from the main body part  12  in  FIG. 1 , through a center-coil opening  96  in a high energy spring  98  and into a round pivot hole  100  in a high energy lever  102  in  FIG. 2 . A horizontal spring leg  104  of the high energy spring  98  urges the high energy lever  102  to pivot or swing counterclockwise about the pivot-support post  94  as in  FIGS. 6-9 . As is known in the prior art, the high energy lever  102  is normally latched in place in an initial or home position shown in  FIGS. 3-5  and  10 .  
         [0038]     To make an exposure on film, a shutter release button (not shown) is manually depressed to unlatch the high-energy lever  102  as is known in the prior art. The high energy lever  102  is then pivoted counterclockwise about the pivot-support post  94  in  FIGS. 6-9 , via the horizontal spring leg  104  of the high energy spring  98 . A striker finger  106  on the high energy lever  102  swiftly impacts against (strikes) a strike tab  108  on a resilient cantilever beam  110  extending from the horizontal driver leg  70  of the L-shaped driver  20 , to quickly translate the L-shaped driver in the single forward direction  86 . As a result, the L-shaped driver is advanced to cause the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  away from one another, i.e. clockwise and counter clockwise about the pivot-support posts  24  and  30  in  FIGS. 6, 7  and  10 , to uncover the exposure aperture  36 , and to cause the upstanding switch drive finger  90  on the horizontal driver leg  70  to push the movable switch contact  54  (in opposition to the urging of the return spring  60 ) to pivot the movable switch contact, i.e. counterclockwise about the pivot-support post  56  in  FIGS. 6-9 , against the leaf-spring switch contact  52  to close the shutter-flash synchronization switch  18 . The shutter-flash synchronization switch  18  is closed at the same time that the blade-drive posts  74  and  80  pivot the first and second shutter blades  28  and  34  away from one another to uncover the exposure aperture  36 .  
         [0039]     As shown in  FIGS. 6-8 , after the striker finger  106  on the high energy lever  102  strikes the strike tab  108  on the resilient cantilever beam  110 , the striker finger swings slightly beyond the strike tab. This allows the return spring  60  to pivot the movable switch contact  54  away from the leaf-spring switch contact  52 , i.e. clockwise about the pivot-support post  56  in  FIGS. 3-5  and  10 , to re-close the shutter-flash synchronization switch  18 . The movable switch contact  54  pushes against the switch drive finger  90  on the L-shaped driver  20  to translate the L-shaped driver in the single reverse direction  88 , which causes the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  towards one another to recover the exposure aperture  36 .  
         [0040]     Then, as is known in the prior art a metering cam (not shown) is manually rotated during film rewinding to return the high energy lever  102  to its initial or home position by pivoting the high energy lever clockwise about the pivot-support post  94  in  FIGS. 3-5  and  10  (in opposition to the urging of the horizontal leg  104  of the high energy spring  98 ). As the striker finger  106  on the high energy lever  102  is being returned past the strike tab  108  on the resilient cantilever beam  110 , the beam is temporarily or momentarily deflected or bent to shift the strike tab out of the way of the striker finger. This is done without moving the L-shaped driver  20 . Once the striker finger  106  is returned past the strike tab  108 , the resilient cantilever beam  110  elastically straightens.  
       Interchangeability of the Shutter Blades  
       [0041]     The first and second shutter blades  28  and  34  are exactly identical to make them readily interchangeable as shown in  FIG. 1 , for ease of manufacture of the camera  10 . For this purpose, the first blade  28  has an unused drive slot  112  that is aligned with and below the pivot hole  26  and the used drive slot  76  in the first shutter blade, and the second blade  34  has an unused drive slot  114  that is aligned with and below the pivot hole  32  and the used drive slot  82  in the second shutter blade. See  FIGS. 1 and 2 . The unused drive slots  112  and  114  are spaced the same distance from the pivot holes  26  and  32  as are the used drive slots  76  and  82  spaced from the pivot holes.  
       Preventing Shutter-Rebound or Shutter-Bounce  
       [0042]     As shown in  FIGS. 1, 9  and  10 , the main body part  12  and the L-shaped driver or slider  20  have parallel similarly-inclined ramp and follower faces  116  and  118 . Preferably, the ramp and follower faces  116  and  118  are each flat and are each inclined at an acute angle within the range of 9°-15° (preferably 11.8°). The ramp face  116  serves as a fixed stop for the L-shaped driver  20  in  FIG. 10 .  
         [0043]     When the L-shaped driver  20  is translated in the single reverse direction  88  to cause the blade-drive posts  74  and  80  on the L-shaped driver to pivot the first and second shutter blades  28  and  34  towards one another to recover the exposure aperture  36 , the follower face  118  on the L-shaped driver is moved to abut against the ramp face  116  on the main body part  12  as in  FIGS. 9-10 . The ramp face  116 , in cooperation with the follower face  118 , stops the L-shaped driver  20  and due to its incline tends to urge or cam or lift the L-shaped driver slightly upward in  FIG. 10  to create a high friction-type relation between the blade-drive post  74  on the L-shaped driver and a peripheral edge or surface  120  of the translation-support slot  78  in the face plate  22  and between the blade drive post  80  on the L-shaped driver and a peripheral edge or surface  122  of the translation-support slot  84  in the face plate. The friction-type relation is created because the blade-drive post  74  is urged firmly the peripheral edge  120  and the blade drive post  80  is urged firmly against the peripheral edge  122 . This then acts to impede or retard translation of the L-shaped driver  20  in the single forward direction  86 , that would cause the blade-drive posts  74  and  80  to pivot the first and second shutter blades  28  and  34  away from one another to unintentionally uncover the exposure aperture  36 . Thus, there can be no shutter-round or shutter-bounce.  
         [0044]     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, the single-piece driver  20  is shown in  FIGS. 1 and 2  with an optional driver-support post  124  that projects forward to rest on the face plate  22 . The driver-support post  124  is slightly shorter than the blade-drive posts  74  and  80  on the single-piece driver  20 .