Patent Publication Number: US-7715707-B2

Title: Zoom ratio adjusting switch

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to an optical device with a zoom lens and, particularly, to a zoom ratio adjusting switch. 
   2. Description of Related Art 
   Various types of compact cameras equipped with zoom lenses have been put on the market. Motor driven compact cameras of this kind are equipped with a zoom ratio adjusting switch for actuating an electric motor to drive the zoom lens to adjust a zoom ratio. 
   One conventional zoom ratio adjusting switch comprises a camera panel and a rotary member. The panel defines three arc-shaped and elongated grooves therethrough, which are uniformly arranged in the panel, adjoining an outermost portion of a round region of the panel. The rotary member comprises a base attached to a side of the round region of the panel, and three elastic fingers extending perpendicularly from the base. The elastic fingers respectively elastically extend through the grooves and grasp an opposite side of the round region of the panel, to thereby secure the rotary member to the panel. The elastic fingers can slide in the grooves along a circumferential direction of the round region of the panel. Thus, the rotary member is kept in a neutral position until acted on by a force to rotate between a tele-angle end position and a wide-angle end position. Specifically, the electric motor rotates in one direction to shift the zoom lens toward the telephoto side while the rotary member is turned toward the tele-angle end position, and rotates in a reverse direction to shift the zoom lens toward the wide-angle end while the rotary member is turned to the wide-angle end position. 
   In order to firmly secure the rotary member to the panel, a diameter of the round region of the panel must be slightly larger than a diameter of a circle defined by innermost extremities of the elastic fingers. The elastic fingers must be expanded outwardly to extend through the grooves in the panel, and then rebound to grasp said opposite side of the round region of the panel. However, the elastic fingers are slim and at risk of being broken due to excessive force or deformation. As a result, the zoom ratio adjusting switch is unreliable. 
   What is needed, therefore, is a zoom ratio adjusting switch which is reliable and durable. 
   SUMMARY 
   In accordance with a present embodiment, a zoom ratio adjusting switch includes a panel, a rotary member, and a spring. The panel defines first and second grooves whose innermost extremities are on a circumference of a circle. Each groove includes a wide part and a narrow part. The rotary member includes a body positioned to a top side of the panel and first and second locking legs extending from the body. The first and second locking legs extend though the wide parts and slide in the narrow parts respectively. Feet extend from the locking legs respectively at the bottom side of the panel and are restrained at the bottom side of the panel. The spring is positioned to the bottom side of the panel and restrains travel of the first locking leg from the narrow part to the wide part of the first groove. 
   Other advantages and novel features will be drawn from the following detailed description of at least one preferred embodiment, when considered in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded, isometric view of a zoom ratio adjusting switch, according to a preferred present embodiment. 
       FIG. 2  is similar to  FIG. 1 , but viewed from a different angle. 
       FIG. 3  is an assembled, isometric view of  FIG. 1 . 
       FIG. 4  is an assembled, isometric view of  FIG. 2 . 
       FIG. 5  is similar to  FIG. 4 , but a rotary member of the zoom ratio adjusting switch is turned to a tele-angle end position. 
       FIG. 6  is similar to  FIG. 4 , but a rotary member of the zoom ratio adjusting switch is turned to a wide-angle end position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An embodiment of the present zoom ratio adjusting switch will now be described in detail below and with reference to the drawings. 
   Referring to  FIGS. 1-2 , a zoom ratio adjusting switch  10  in accordance with a preferred present embodiment comprises a camera panel  100 , a spring  200 , and a rotary member  300 . The rotary member  300  is rotatably secured to the camera panel  100 . The spring  200  preferably is a torsion spring in the embodiment. The torsion spring  200  forces the rotary member  300  to remain in a neutral position and can restrain circumferential travel of the rotary member  300  between a tele-angle end position designated by a sign “T” and a wide-angle end position indicated by a sign “W”. The torsion spring  200  can also facilitate return of the rotary member  300  to the neutral position. 
   The panel  100  forms a round region  110  and defines first and second elongated arch-shaped grooves  120 ,  130 . The first and second grooves  120 ,  130  extend along and adjoin an outermost circumference of the round region  110 . That is, innermost extremities of the first and second grooves  120 ,  130  are on a circumference of a circle. In the embodiment, the first groove  120  is near a front side of the panel  100  and the second groove  130  is near a rear side of the panel  100  in the embodiment. Each groove  120 / 130  comprises a wide part  122 / 132  and a narrow part  124 / 134 . First and second arch-shaped flanges  126 ,  136  are formed on the panel  100 , respectively adjoining the narrow parts  124 ,  134  away from the round region  110 . 
   Primarily referring to  FIG. 2 , at a bottom side of the panel  100 , a pole  140  extends from a central portion of the round region  110 , perpendicular to the round region  110 . A tab  142  is formed at a free end of the pole  140 , parallel to the round region  110 . The tab  142  is oriented toward the narrow part  134  of the second groove  130 . A pair of recesses  152 ,  154  is defined in the round region  110 . The recesses  152 ,  154  are separated by two ribs  162 ,  164 , which extend along radial directions of the round region  110  and cooperatively enclose a fan-shaped area adjoining an innermost extremity of the narrow part  124  of the first groove  120 . 
   The torsion spring  200  comprises a central loop  210 , first and second arms  212 ,  214  extending from opposite ends of the loop  210 . The arms  212 ,  214  are configured to sandwich the ribs  162 ,  164  of the round region  110  therebetween when the rotary member  300  is in neutral position. 
   The rotary member  300  comprises an annular body  310 , first and second locking legs  320 ,  330  extending perpendicularly from a lower side of the annular body  310 . A knob  340  is formed at an outer side of the annular body  310  near the first locking legs  320  for facilitating rotation of the rotary member  300 . The locking legs  320 ,  330  are located diametrically opposite each other. The first locking leg  320  forms a foot  322  extending outwardly from a free end thereof. The foot  322  and the free end of first the locking leg  320  commonly define a planar bottom surface. The second locking leg  330  forms a foot  332  extending outwardly from a free end thereof. The foot  332  and the free end of the second locking leg  330  commonly define a planar bottom surface. The feet  322 ,  332  are parallel to the body  310 . The flanges  126 ,  136  are disposed between the feet  322 ,  332  and the body  310 , and prevent the locking legs  320 ,  330  from escaping from the panel  100  at the narrow parts  124 ,  134  of the first and second grooves  120 ,  130 . 
   Referring to  FIGS. 1-4 , in assembly of the zoom ratio adjusting switch  10 , the locking legs  320 ,  330  respectively extend though the wide parts  122 ,  132  of the grooves  120 ,  130  from a top side of the round region  110 . The feet  322 ,  332  extend to a lower side of the round region  110 . The annular body  310  of the rotary member  300  is rested on the top side of the round region  110 . The rotary member  300  is rotated so that the locking legs  320 ,  330  enter the narrow parts  124 ,  134  of the grooves  120 ,  130 , until the rotary member  300  is in neutral position. The loop  210  of the torsion spring  200  is sleeved around the pole  140  and restrained by the tab  142  from escaping from the pole  140 . The first arm  212  is positioned in the recess  152  and the second arm  214  is positioned in the recess  154 . When the torsion spring  200  is in a normal state, the rotary member  300  remains in a neutral position, the first and second arms  212 ,  214  sandwich the first leg  320  and the ribs  162 ,  164  therebetween. 
   Particularly referring to  FIGS. 1-2  and  5 , rotating the rotary member  300  toward the tele-angle end position, the legs  320 ,  330  in the narrow parts  124 ,  134  move toward the wide parts  122 ,  132  of the first and second grooves  120 ,  130 . The first leg  320  exerts a force on the first arm  212  and pushes the first arm  212  outwardly; thus, the first arm  212  expands outwardly relative to the second arm  214 , which is blocked by the rib  164 . However, travel of the first arm  212  is restrained in the recess  152 . When the rotary member  300  arrives at the tele-angle end position, the first arm  212  restrains further movement of the legs  320 ,  330  toward the wide parts  122 ,  132  of the first and second grooves  120 ,  130 . Releasing the rotary member  300 , the first arm  212  of the torsion spring  200  rebounds and pushes the legs  320 ,  330  to move reversely to be sandwiched between the first and second arms  212 ,  214 . The rotary member  300  thereby returns to the neutral position. 
   Referring to  FIGS. 1-2  and  6 , rotating the rotary member  300  toward the wide-angle end position, the legs  320 ,  330  in the narrow parts  124 ,  134  move farther away from the wide parts  122 ,  132  of the first and second grooves  120 ,  130 . The first leg  320  exerts a force on the second arm  214  and pushes the second arm  214  outwardly; thus, the second arm  214  expands outwardly relative to the first arm  212 , which is blocked by the rib  162 . However, travel of the second arm  214  is restrained in the recess  154 . When the rotary member  300  arrives at the wide-angle end position, the second arm  214  restrains further movement of the legs  320 ,  330  in the narrow parts  122 ,  132 . It is understood that further movement of the legs  320 ,  330  can be restrained by innermost extremities of the narrow parts  124 ,  134  of the first and second grooves  120 ,  130 . Releasing the rotary member  300 , the second arm  214  of the torsion spring  200  rebounds and pushes the legs  320 ,  330  to move reversely to be sandwiched between the first and second arms  212 ,  214 . The rotary member  300  thereby returns to the neutral position. 
   In the embodiment, the locking legs  320 ,  330  extend through the grooves  120 ,  130  without being deformed. This sufficiently decreases the risk of breaking the locking legs  320 ,  330  due to excessive force or deformation, compared with conventional zoom ratio adjusting switches employing elastic fingers. Additionally, rigid material can be used to manufacture the locking legs  320 ,  330 , since the locking legs  320 ,  330  can extend through the grooves  120 ,  130  without deformation. Other components, such as a pressing button  400  can be positioned between the rotary member  300  and the camera panel  100 . 
   It will be understood that the above particular embodiments and methods are shown and described by way of illustration only. The principles and features of the present invention may be employed in various and numerous embodiments thereof without departing from the scope of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.