Abstract:
A camera shutter driving mechanism includes a film-driven ratchet mechanism rotated by a film moving through a film passage in a camera, and a shutter release sensing mechanism located adjacent to and rotated by the film-driven ratchet mechanism to convert an axial pressure applied on a shutter release button into a rotary force that is acted on a link via a pull arm of the shutter release sensing mechanism, so that the link is moved horizontally to cause pivotal turning of a shutter blade from a closed position into an open position to admit external light into the camera.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a camera structure, and more particularly to a shutter driving mechanism for a camera. 
     2. Description of the Prior Art 
     A camera generally includes a casing, a film cartridge chamber, a film take-up chamber, a taking lens, a viewfinder, a shutter, a shutter release button, a shutter driving mechanism, and other related parts. When. a user pushes the shutter release button, external light is allowed to pass through the taking lens to present an image on the film. 
     When the user pushes the shutter release button, such movement of pushing is transferred via the shutter driving mechanism to cause opening of a shutter blade for a very short time to admit external light into the camera. Therefore, the shutter driving mechanism plays a very important role in the camera. Some of the conventional shutter driving mechanisms have very complicate structures and occupy considerable spaces in the camera, while others have simplified structure but less precise functions. Various parts included in the complicate shutter driving mechanisms are interdependent and therefore tend to cause failures of the shutter driving mechanisms. On the other hand, the simplified shutter driving mechanisms might be too simple to provide precise control of shutter. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to provide a camera shutter driving mechanism capable of precisely transferring a user&#39;s movement of pushing the shutter release button to control the opening or closing of shutter. 
     Another object of the present invention is to provide a camera shutter driving mechanism having simplified structure and limited number of components to occupy a reduced space in the camera. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein: 
     FIG. 1 a front perspective view of a camera having a shutter driving mechanism according to the present invention; 
     FIG. 2 is an exploded rear perspective view of a camera frame of the camera of FIG. 1; 
     FIG. 3 is an exploded front perspective view of the camera of FIG. 1; 
     FIG. 4 is a fragmentary, enlarged exploded perspective view of FIG. 3 showing the camera shutter driving mechanism of the present invention; 
     FIG. 5 is an assembled perspective view of the camera shutter driving mechanism of FIG. 4 viewed from another angle thereof; 
     FIG. 6 shows movements of all related components of the camera shutter driving mechanism of FIG. 5 when a shutter blade thereof is in a closed position; 
     FIG. 7 shows movements of all related components of the camera shutter driving mechanism of FIG. 5 when the shutter blade thereof is in an open position; and 
     FIG. 8 shows movements of all related components of the camera shutter driving mechanism of FIG. 5 when the shutter blade thereof is returned from the open position to the closed position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to FIG. 1 that illustrates a camera having a front cover  1  and a camera frame  2  that are connected together to define an internal space between them. 
     The front cover  1  is provided near a central area with an opening  11 , via which external light needed to take a picture passes through a taking lens of the camera. A viewfinder  12  is provided on the front cover  1  above the opening  11 . Moreover, the front cover  1  is provided at a predetermined position with an integrally formed shutter release button  13 . When the shutter release button  13  is pushed, it will press against a shutter driving mechanism located in the front cover  1 . The shutter driving mechanism will be described in more details latter. 
     As shown in FIG. 2 that is an exploded rear perspective view of the camera frame  2  of the camera, the camera frame  2  is provided at two ends of a rear side thereof with a film cartridge chamber  21  and a film take-up chamber  22 , respectively, so that a film passage  23  is formed between the two chambers  21 ,  22 . A film cartridge  31  having a film  3  wound therein can be positioned in the film cartridge chamber  21 , and a leader of the film  3  in the film cartridge  31  may be drawn out to pass through the film passage  23  and connect to a film take-up reel  32  that is positioned in the film take-up chamber  22 , so that the film  3  is set in the camera. The film  3  is provided along upper and lower edges with a line of sprocket holes  30  each. 
     The film cartridge chamber  21  is provided at a top with a film winding wheel  211  that may be turned by a user to wind the film  3  in the film cartridge  31 . 
     A film-driven sprocket wheel  231  is provided near an upper side of the film passage  23  to slightly project into the film passage  23 . When the film  3  is drawn to pass through the film passage  23 , sprockets on the film-driven sprocket wheel  231  engage into the upper line of sprocket holes  30  on the film  3 . Thus, when a user turns the film winding wheel  211  to wind the film  3 , the film-driven sprocket wheel  231  is driven by the displacing film  3  to rotate. 
     At least one battery  5  is positioned in a battery compartment provided at a bottom of the camera frame  2  to supply power needed by the camera. The battery compartment is openably closed with a battery cover  24 . A rear cover  4  is pivotally connected to the camera frame  2  for closing a rear side of the camera frame  2  to provide a close and light-tight space at the rear side of the camera frame  2 . 
     Please refer to FIG.  3 . The camera frame  2  is provided at a front side with a shutter opening  25 . As can be clearly seen in FIG. 4, a flat shutter blade  6  having a shaft hole  61  and a claw  62  is located in front of the shutter opening  25  by engaging the shaft hole  61  with a locating shaft  63  fixed in the camera frame  2  above the shutter opening  25 , such that the shutter blade  6  is pivotally rotatable about the locating shaft  63 . When the shutter blade  6  is in a closed position to locate immediately in front of the shutter opening  25  to shield the latter, as shown in FIG. 5, the shutter blade  6  is pulled by a pullback spring  64  to remain in this position. And, when the shutter blade  6  is turned about the locating shaft  63  to an open position to offset from the shutter opening  25 , as shown in FIG. 7, external light is permitted to pass through the shutter opening  25 . 
     Please refer back to FIG. 3. A viewfinder frame  26  is provided in the camera frame  2  above the shutter blade  6  and includes a front lens  261  and a rear lens  262 . The front lens  261  is in a position fitly corresponding to the viewfinder  12  on the front cover  1 . 
     There is a shutter cover  71  mounted in front of the shutter blade  6 . The shutter cover  71  includes a taking lens aperture  72  provided at a central area thereof, and a forward projected ring-shaped taking lens holder  73  surrounding the taking lens aperture  72  for holding a taking lens  74  therein. A taking lens cover  75  is then fixed onto the shutter cover  71  to locate the taking lens  74  in the taking lens holder  73 . 
     There is also a shutter actuating mechanism  8  provided above the shutter blade  6  for controlling movement of the shutter blade  6 . A top cover  27  is provided to cover entire top of the camera frame  2 . The top cover  27  includes an extension arm  271  that is located below the shutter release button  13  on the front cover  1  and above the shutter actuating mechanism  8 . 
     Please refer to FIGS. 3 to  5  at the same time. The shutter actuating mechanism  8  includes a film-driven ratchet mechanism  81 , a shutter release sensing mechanism  82  located adjacent to the film-driven ratchet mechanism  81 , and a link  83 . 
     The film-driven ratchet mechanism  81  includes a shaft  810  coaxially connected to the film-driven sprocket wheel  231 , and a ratchet disc  811  provided at an upper part of the shaft  810 . The ratchet disc  811  is provided at its peripheral edge with a curved projection  812  and a recess  813  adjacent to the projection  812 . When the film  3  is wound and drives the film-driven sprocket wheel  231  to turn, the shaft  810  and the ratchet disc  811  coaxially connected to the film-driven sprocket wheel  231  rotate at the same time. 
     The shutter release sensing mechanism  82  includes a post  821  vertically fixed in the camera frame  2 , a first coupler  822  movably mounted around the post  821 , a pull arm  823  radially extended from a lower periphery of the first coupler  822  and having a hook-like free end, a spring  824  put around the first coupler  822 , a second coupler  825  mounted around the post  821  to vertically slidably engage with the first coupler  822 , a top disc  826  formed at a top of the second coupler  825 , a first lever  827  projected from a peripheral edge of the top disc  826  toward the ratchet disc  811  of the film-driven ratchet mechanism  81  to contact with the curved projection  812 , a second lever  828  projected from the peripheral edge of the top disc  826  toward the film winding wheel  211  to contact with teeth provided on a circumferential surface of the wheel  211  and to contain a predetermined angle between it and the first lever  827 , and a stud  829  upward projected from a top of the second lever  828  to locate below the extension arm  271  of the top cover  27  of the camera frame  2 . 
     A locating plate  814  is provided in the camera frame  2  above the film-driven ratchet mechanism  81  and the shutter release sensing mechanism  82 , so that the shaft  810  of the film-driven ratchet mechanism  81  and the post  821  of the shutter release sensing mechanism  82  are fixed at their upper end to the locating plate  814 . 
     The link  83  is coupled at a first end with the hook-like free end of the pull arm  823  at the bottom of the first coupler  822 , and at a second end with a pullback spring  831  fixed in the camera frame  2 . When the pull arm  823  is swung, it pulls the link  83  to move along a horizontal channel  28  provided in the camera frame  2  in a first direction I. The link  83  is provided near a middle portion of a front side facing the shutter blade  6  with a forward protrusion  832  to detachably abut on the claw  62  of the shutter blade  6 . In the illustrated embodiment of the present invention, the protrusion  832  is in the form of a triangular stub having a bevel surface  832   a  facing toward the first end of the link  83 , and a vertical wall  832   b  facing toward the second end of the link  83 . 
     Please refer to FIGS. 6 to  8 . When a user turns the film winding wheel  211 , the film  3  is wound to displace in the film passage  23  and drives the film-driven sprocket wheel  231  and accordingly the shaft  810  coaxially connected to the film-driven sprocket wheel  231  to rotate counterclockwise. Since the top disc  826  of the shutter release sensing mechanism  82  is in contact with the ratchet disc  811  of the film-driven ratchet mechanism  81 , it is brought by the latter to rotate by an angle at the same time. 
     When the film  3  displaces a distance equal to a standard frame, the curved projection  812  on the ratchet disc  811  is turned into a position of pressing against the first lever  827  of the top disc  826 . At this point, a free end of the second lever  828  of the top disc  826  is moved into a position between two teeth on the film winding wheel  211 , stopping the film winding wheel  211  from moving any further. 
     When the top disc  826  rotates, it brings the pull arm  823  to rotate clockwise at the same time, causing the link  83  connected at the first end to the free end of the pull arm  823  to move in the first direction I. When the bevel surface  832   a  of the triangular stub  832  on the link  83  passes over a top of the claw  62  of the shutter blade  6 , the vertical surface  832   b  of the triangular stub  832  will abut on a left side of the claw  62 , as shown in FIG.  6 . 
     When the user pushes the shutter release button  13 , the latter depresses the extension arm  271  of the top cover  27  for the same to press against the stud  829  on the second lever  828  of the top disc  826 , causing the entire top disc  826  to axially descend in a second direction II to finally separate the first lever  827  of the top disc  826  from the curved projection  812  of the ratchet disc  811 . At this point, the link  83  is pulled by a restore force of the pullback spring  831  to move in a direction opposite to the first direction I. When the link  83  is moved toward the pullback spring  831 , the vertical wall  832   b  of the triangular stub  832  on the link  83  pushes the claw  62  of the shutter blade  6 , causing the latter to turn about the locating shaft  63  by a predetermined angle to the open position to expose the shutter opening  25 , as shown in FIG. 7, so that external light is admitted through the shutter opening  25 . 
     When the link  83  is pulled by the pullback spring  831  to a dead point, the triangular stub  832  is moved beyond and separates from the claw  62  of the shutter blade  6 , and the latter is pulled by the pullback spring  64  back to the closed position, as shown in FIG.  8 . 
     The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications in the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.