Abstract:
A focus retaining mechanism of a camera is disclosed. The camera includes a base, a focusing lens, a retaining member, and a retaining hook. The base has a cylindrical and vertical opening in it. The focusing lens is rotationally fixed within the opening. The retaining member is horizontally and movably fixed in the base. The horizontal sides of the retaining member include a ratchet side, a smooth side, a first end and a second end positioned over the connecting portions of the ratchet side and the smooth side. The retaining hook has a horizontal arm and a vertical arm installed under the horizontal arm. The horizontal arm can move horizontally across the upper side of the retaining member, and the vertical arm can thus contact each of the horizontal sides of the retaining member.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a focus retaining mechanism, and more particularly, to a focus retaining mechanism of a camera. 
     2. Description of the Prior Art 
     Please refer to FIG. 1 of a top view of a conventional lens driving device  10  of a camera. The lens driving device  10  is disclosed in U.S. Pat. No. 5,680,649 “LENS DRIVING DEVICE FOR AUTO-FOCUS CAMERA”. The lens driving device  10  comprises a base  12  comprising a cylindrical opening 16 , a focusing lens  14  rotatably mounted within the opening 16 , a lens setting ring  40  rotatably mounted on the periphery of the opening  16  on the base  12 , a driving ring  44  mounted on the base  12  by hooking the lens setting ring  40 , a cam portion  42 , a lens barrel  18  mounted on the base  12  by hooking the lens setting ring  40  and the cam portion  42 , a first bi-directional driving motor  20  and a second bidirectional driving motor  30  mounted on the base  12 , a spring  34  mounted on the base  12 , and a retainer member  22  disposed on the base  12 . In addition, a cylindrical projection  46  disposed on the lens setting ring  40  hooks an engaging portion  19  of the lens barrel  18 . Thus, when the lens setting ring  40  is rotated, the lens barrel  18  and the focusing lens  14  are also rotated. The second bidirectional driving motor  30  is used to rotate the driving ring  44  for controlling a shutter. The first bi-directional driving motor  20  is used to drive the retainer member  22  for mounting the cam portion  42  in a predetermined position so as to rotate the focusing lens  14  to a corresponded position. Moreover, an idler gear  70  and a first ratchet  50  are used for the transmission between the cam portion  42  and the retainer member  22 . 
     As shown in FIG. 1, when the second bi-directional driving motor rotates the driving ring  44  toward a positive direction via a second ratchet  32  to control an opening position of the shutter, the driving ring  44  moves the lens setting ring  40  so as to rotate the lens barrel  18  and focusing lens  14 . At the same time, the lens setting ring  40  also moves the retaining member  22  so that a plurality of gear portions  43  hook with a hold lever  60  one by one. The retaining member  22  rotates the first ratchet  50  by hooking the idler gear  70 . 
     When the second bi-directional driving motor  30  moves the driving ring  44  toward a positive direction to a predetermined position, which is an appropriate position for focusing, the first bi-directional driving motor  20  controls the retainer member  22  to stop rotating the first ratchet  50 . At this time, a pull-back action to the retaining member  22  generated by the flexible component  34  is stopped due to the stop action of the retainer member  22 . Thus, the lens barrel  19  and the driving ring  44  do not circumrotate so that the lens driving device  10  can focus and retain position. At this time, the driving ring  44  moves to a predetermined shutter position and opens the shutter, and the lens barrel  18  also drives the focusing lens  14  to rotate to a corresponding position. 
     The second bi-directional driving motor  30  continues to rotate in a positive direction and moves the driving ring  44  to an utmost position  45 . At the same time, the first bi-directional driving motor  20  drives the retainer member  22  to rotate the first ratchet  50  so that the first ratchet  50  and the cam portion  42  rotate to corresponding utmost positions. At this time, the second bi-directional driving motor  30  provides no power to the lens driving device  10 . That means after the second bi-directional driving motor  30  moves the driving ring  44  to a utmost position  45 , only the first bi-directional driving motor  20  provides a small amount of power to back focus retaining structures such as the first ratchet  50 , the cam portion  42 , the lens barrel  18 , the driving ring  44 , and the flexible component  14  to an initial state. After the first bi-directional driving motor  20  drives the retainer member  22  and the first ratchet  50  to their utmost positions, the first ratchet  50  does not contact with the retainer member  22 , and a spring  62  disposed on the base  12  pulls the hold lever  60  back to the initial state. This is an action of closing the shutter. In addition, the flexible component  34  also pulls the cam portion  42  back to the initial state so that the driving ring  44 , lens barrel  18 , and the first ratchet  50  are also moved back to the initial states. 
     As described above, the conventional lens driving device  10  has a complicated focus retaining structure, and a retainer member and a gear assembly are needed. Thus, the complexity and costs of components are increased. This highly complicated structure hardly reduces costs of assembly. In addition, although the retainer member  22  acts effectively, the available space of the lens driving device  10  is decreased with the use of the retainer member  22 . 
     SUMMARY OF INVENTION 
     It is therefore a primary objective of the claimed invention to provide a focus retaining mechanism to solve the above-mentioned problems. 
     The claimed invention provides a focus retaining mechanism of a camera. The camera comprises a base, a focusing lens, a retaining member, and a retaining hook. The base comprises a cylindrical and vertical opening therein. The focusing lens is rotationally fixed within the opening. The retaining member is horizontally and movably fixed in the base. The horizontal sides of the retaining member include a ratchet side, a smooth side, a first end and a second end positioned over the connecting portions of the ratchet side and the smooth side. The retaining hook has a horizontal arm and a vertical arm installed under the horizontal arm. The horizontal arm can move horizontally across the upper side of the retaining member, and the vertical arm can thus contact each of the horizontal sides of the retaining member. 
     It is an advantage of the claimed invention that a focus retaining mechanism of a camera with a simple design is used for simplifying the focus retaining mechanism 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a top view of a lens driving device in the prior art. 
     FIG. 2 is a simplified top view of a lens driving device in the first embodiment of the present invention. 
     FIG. 3 is an exploded diagram of all components of the lens driving device shown in FIG.  2 . 
     FIG. 4 is a simplified front view of the lens driving device shown in FIG.  3 . 
     FIG. 5 is a simplified front view of a lens driving device in the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     In the present invention, mechanisms for moving a shutter and method thereof are the same as the prior art shown in FIG.  1  . Please refer to FIG. 2, FIG. 3, and FIG.  4 . FIG. 2 is a simplified top view of a lens driving device  100  of a first embodiment of the present invention. FIG. 3 is an exploded diagram of components of the lens driving device  100  in FIG.  2 . FIG. 4 is a simplified front view of the lens driving device  100  in FIG. 3 after assembly. 
     As shown in FIG.  2  and FIG. 3, the lens driving device  100  comprises a base  102  comprising a cylindrical lens barrel  106 , a focusing lens  104  rotatably mounted on the lens barrel  106 , a connecting ring  114 , a retaining member  120  and a driving ring  110  rotatably mounted on the periphery of the base  12 , a retaining hook  130  mounted on the base  102 , a flexile component  136  mounted on the base  102 , a driving motor  140  mounted on the base  102 , and a first gear  142  and a second gear  144  mounted on the base  102  by hooking with the driving ring  110  and the retaining member  120  respectively. 
     The retaining member  120  is an arc-shaped component with a ratchet side in the horizontal direction on an outer side of the retaining member  120 , a smooth side  124  with a sidewall of a guide groove  125  on an inner side of the retaining member  120 , a first end  126  and a second end  128  disposed on two ends between the ratchet side  122  and the smooth side  124 . A gear side  123  disposed on the bottom of the ratchet side  122  comprises a plurality of gears as a transmission interface. In addition, the retaining hook  130  comprises a horizontal arm  132  movably mounted on the base  102  and a vertical end  134  mounted beneath the horizontal arm  132 . The horizontal arm  132  and the vertical end are monolithically formed by a flexible material such as metallic wire. The middle portion of the metallic wire is ring like and surrounds a shaft  103  on the base  102 . Both ends of the metallic wire extended from the middle portion together form a “V” shape. The horizontal arm  132  and the vertical end  134  are formed on one end. The other end props up the sidewall of the base  102 . Thus, one end of the horizontal arm  132  is mounted on the shaft  103  so as to rotate flexibly. 
     The flexible components  36  is connected to a transmission lever  113  on the connecting ring  114  for mounting the connecting ring  114  flexibly so as to move and hook the driving ring  110  and the retaining member  120 . The driving ring  110  comprises a gear side  111  extruded to the ringlike edge for hooking a top gear portion  143  of the first gear  142 . The driving motor  140  drives the first gear  142  to rotate via the bottom gear portion  141  of the first gear  142 . Since the top gear portion  143  of the first gear  142  has a smaller diameter than the bottom gear portion  141 , the first gear  142  shrinks the rotating momentum of the related motion of the driving ring  110  to the driving motor  140 . The second gear  144  is an amplifying gear with an upside-down design of the first gear  142 . The second gear  144  comprises a bottom gear portion  145  hooking with the gear side  115  of the connecting ring  114  and a top gear portion  146  hooking with the gear side  123  of the retaining member  120 . The connecting ring further comprises a lens connecting lever  117 . When the driving motor  140  drives the first gear  142  to rotate, a front end  112  of the gear side  111  of the driving ring  110  urges the lever  118  on the driving ring  114  so that the connecting ring  114  urges the second gear  144  to rotate so as to move the retaining member  120 . At the same time, the lens connecting lever  117  on the connecting ring  114  moves the focusing lens  104  downward rotatably. The horizontal arm  132  on the retaining hook  130  moves horizontally above the retaining member  120  so that the vertical end  134  of the horizontal arm  132  touches each horizontal side of the retaining member  120 . In addition, the sidewall of a guide groove  125  on the smooth side  124  of the retaining member  120  is used to place the vertical end  134  of the retaining hook  120 . When vertical end  134  of the retaining hook  130  passes through the second end  128  of the retaining member  120 , the vertical end  134  is guided to the sidewall of a guide groove  125  of the smooth side  124 . The sidewall of the guide groove  125  of the smooth side  124  guides the vertical end  134  along the smooth side  124  to the first end  126  of the retaining member  120 . 
     As shown in FIG. 4, when the driving motor  130  urges the driving ring  110  to rotate in a positive direction via the first gear  142 , the driving ring  110  moves the connecting ring  114  so that the lens connecting lever  117  on the connecting ring  114  moves the focusing lens  104  downward rotatably along the lens barrel  106 . At the same time, the connecting ring  114  moves the retaining member  120  via the second gear  144 . A pull-back force generated by the flexible component  136  acts on the transmission lever  116  on the connecting ring  114 . The vertical end  134  of the retaining hook  130  contacts the ratchet side  122  of the retaining member  120  at the first end  126  and slides along the ratchet side  122 . When the driving motor  140  keeps the driving ring  110  moving in the positive direction to a predetermined position, which is a proper position for focusing, the driving motor  140  stops to move the focusing lens  104  downward via the connecting ring  114 . At the same time, the vertical end  134  of the retaining hook  130  hooks with the ratchet side  122  of the retaining member  120 . Thus, the position of the retaining member  120  is fixed without moving by the elastic force generated by the flexible component  136  to achieve functions of focusing and retaining. 
     The ratchet side  122  comprises a plurality of ratchets. Each ratchet provides the focusing lens with a focusing position for satisfying the requirement of different focusing positions. Since a number of the ratchets is corresponding to a number of focusing levels, more focusing positions can be obtained by increasing a number of teeth in the first gear  142  and the second gear  144 . Therefore, the focus control can be improved. 
     After the focusing lens  104  completes the action of focusing and retaining, the driving motor  140  reverses. At this time, the retaining member  120  and the connecting ring  114  remain in the retained position, but the driving ring  110  is urged to rotate in an opposite direction so as to move a shutter switch using another end  113  of the gear side  111  to complete a photographing action. 
     After finishing the photographing action, the driving motor  140  turns to rotate in the positive direction and moves the focusing lens  10  downward rotatably via the connecting ring  114 . Finally, the vertical end  134  of the retaining hook  130  leaves the ratchet side  122  of the retaining member  120 , passes through the second end  128  of the retaining member  120  and contacts with the smooth side  124  of the retaining member  120 . At this time, the focus retaining mechanisms of the lens driving device  100 , such as the driving ring  110 , retaining member  120  and the flexible component  126 , already reach corresponded limiting positions. After that, the flexible component  136  pulls the connecting ring  114  so that the lens connecting lever  117  on the connecting ring  114  moves the focusing lens  104  upward rotatably along the lens barrel  106  and the retaining member  120  is rotated in an opposite direction due to the transmission of the second gear  144 . When the flexible component  136  pulls the connecting ring  114  and makes the retaining member  120  rotate reversibly, the driving motor  140  also rotates reversibly so as to prevent generating a reverse rotating force on the retaining member  120 . At this time, the vertical end  134  of the retaining hook  130  slides along the sidewall of the guide groove  125  on the smooth side  124  of the retaining member  120  until passing through the first end  126  of the retaining member  120  to the initial state. In the same manner, the focus retaining mechanism of the lens driving device  100 , such as the driving ring  110 , the retaining member  120  and the flexible component  136 , also back to their initial positions. Thus, a focus retaining process of the lens driving device of the camera  100  is completed. 
     Please refer to FIG. 5 of a simplified top view of a lens driving device  150  of a second embodiment in the present invention. As with the first embodiment, the lens driving device  150  also comprises a base  152  comprising a cylindrical lens barrel  156 , a focusing lens  154  rotatably mounted in the lens barrel  156 , a driving ring  160  rotatably mounted on the periphery of the lens barrel  156 , a retaining member  170  rotatably mounted on the periphery of lens barrel  156 , a flexible component  186  mounted on the base  152 , a connecting ring  164  mounted on the base  152  with hooking the driving ring  160 , a retaining hook  180  disposed on the base  152 , a driving motor  190  mounted on the base  152 , and a first gear  192  and a second gear  194  disposed on the base  152  by hooking with the driving ring  160  and the connecting ring  164  respectively. The retaining member  170  is ring like with an arc-shaped side in a horizontal direction which comprises a ratchet side  172  in an outer side and a smooth side  174  with a sidewall of a guide groove  175  thereof in an inner side, a first end  176  and a second end  178  disposed on two ends between the ratchet side  172  and the smooth side  174 . In addition, the retaining hook  180  comprises a horizontal arm  182  with one end mounted on the base  152  and a vertical end  184  mounted on a bottom of the horizontal arm  182 . The horizontal arm  182  and the vertical end  184  can be formed monolithically by a flexible material such as a metallic wire. 
     The flexible component  186  is connected to a transmission lever  166  of the connecting ring  164  so as to mount the connecting ring  164  flexibly and drive a fixing effect of the driving ring  160  and the retaining hook  180 . The driving motor  190  is used to rotate the first gear  192  so that the retaining member  170  rotates in a first direction. The flexible component  186  is used to provide a driving force of rotating in the first direction or a second direction, which is opposite to the first direction. The connecting ring further comprises a lens connecting lever (not shown in FIG.  5 ). When the driving motor  190  rotate the first gear  192 , the transmission effect of the driving ring  160  and the connecting ring  164  makes the second gear  194  rotate. At the same time, the lens connecting lever on the connecting ring  164  urges the focusing lens  154  to move downward rotatably. The horizontal arm  182  on the retaining hook  180  moves horizontally over the retaining member  170  so that the vertical end  184  mounted beneath the horizontal arm  182  can touch horizontal sides of the retaining member  170 . In addition, the sidewall of the guide groove  175  on the smooth side  174  of the retaining member  170  is used to place the vertical end  184  of the retaining hook  180 . When the vertical end of the retaining hook  180  passes through the second end  178  of the retaining member  170 , the vertical end  184  is guided into the sidewall of the guide groove  175  on the smooth side  174 . The sidewall of the guide groove  175  on the smooth side  174  guides the vertical end  184  to slide along the smooth side  174  to the first end  176  of the retaining member  170 . 
     When the driving motor  190  urges the driving ring  160  to rotate toward a first rotating direction via the first gear  192 , the driving ring  160  urges the connecting ring  164  so as to urge the lens connecting lever on the connecting ring  164  in advance so that the focusing lens  152  moves downward rotatably along the lens barrel  156 . An elastic force of the flexible component  186  acts on the transmission lever  166  of the connecting ring  164 . At this time, the vertical end  184  of the retaining hook  180  moves from the first end  176  of the retaining member  170  to the ratchet side  172  of the retaining member  170  and slides along the ratchet side  172 . 
     When the driving motor  190  continues to urge the driving ring  160  to rotate in the first direction to a predetermined position, which is a proper focusing position, the driving motor  190  stops moving the focusing lens  154  downward via the connecting ring  164 . At this time, the vertical end  184  of the retaining hook  180  hooks with the ratchet side  172  of the retaining member  170  so that the position of the retaining hook  180  is fixed without moving by the elastic force generated by the flexible component  136  to achieve functions of focusing and retaining. 
     The driving motor  190  continues to move the focusing lens  154  rotatably downward via the retaining member  170 , the vertical end  184  of the retaining hook  180  leaves the second end  178  of the retaining member  170  and moves toward the smooth side  174  of the retaining member  170 . At this time, the focus retaining mechanisms of the lens driving device  150 , such as the driving ring  160 , the connecting ring  164 , and the flexible component  186 , are in the limiting position. After that, the flexible component  186  pulls the retaining member  170  via the connecting ring  164  so that the vertical end  184  of the retaining hook  180  slides along the sidewall of the guide grooves  175  on smooth side  174  of the retaining member  170  in the opposite direction until it passes the first end  176  of the retaining member  170  and back to the initial state. At the same time, the lens connecting lever on the connecting ring  164  also urges the focusing lens  154  to move upward rotatably along the lens barrel  156 . Thus, a focus retaining process of the lens driving device of the camera  150  is completed. 
     Comparing FIG.  4  and FIG. 5, the retaining hooks  130  and  170  are used to fix the retaining members  120  and  170  in a way of hooking or propping respectively. Of course, there are some other ways to stop the retaining member from reversing. In addition, the retaining hooks can be movably disposed on the connecting ring or other mechanism rotating with the periphery of the lens barrel. At this case, the retaining member is fixed but the retaining hook is movable. An opposite operating method of the embodiment described above is also a modification or alteration of the claimed invention. In addition, the driving motors and the flexible components shown in FIG.  4  and FIG. 5 can be replaced by other proper driving devices. 
     The ratchet side and the smooth side or the shape of the guide groove shown in FIG. 2 to FIG. 5 can be rearranged in other ways which can provide the retaining member sliding path for rotating in a positive and a negative direction. Besides the composition of a horizontal arm and a vertical end substantially as shown in FIG. 2 to FIG. 5, the retaining hook can be formed of other materials or shapes. The only requirement is the portion of the retaining member hooking with the gear can slide along the ratchet side flexibly when the retaining member rotates in a positive direction. The flexible components in FIG. 2 to FIG. 5 can be replaced by any other driving components that can provide a reverse driving force for rotating. 
     In contrast with the prior art, the lens driving devices  100  and  150  in the present invention are obviously different. The focus retaining mechanisms of the lens driving devices  100  and  150  only use retaining hooks  130  and  180 , which is designed simply, for retaining without adding any other electric device or gear sets. Thus, more space inside the lens driving device of camera is available and the manufacturing cost is also reduced. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.