Abstract:
A lens device includes a base unit, a rotatable barrel component, a press plate, and a lens unit. The base unit includes a base plate, and a stationary barrel component connected to the base plate and extending there from a long an axis. The rotatable barrel component is sleeved rotatably on the stationary barrel component. The press plate has at least one fixing end portion secured to the base unit, and a press section connected to the fixing end portion. The press section is elastically deformable relative to the fixing end portion and is disposed to abut against an annular outer surface of the rotatable barrel component to resist axial movement of the rotatable barrel component. The lens unit is driven to move relative to the base unit along the axis upon rotation of the rotatable barrel component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of Taiwanese Application No. 095119869, filed on Jun. 5, 2006. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to optical equipment, more particularly to a lens device that can operate precisely during zoom adjustment. 
         [0004]    2. Description of the Related Art 
         [0005]    As shown in  FIG. 1 , a conventional lens device includes a base  1 , a stationary barrel component  2  mounted to the base  1 , a rotatable barrel component  3  sleeved rotatably on the stationary barrel component  2 , a first lens unit  4  extending into the stationary barrel component  2 , a second lens unit  5 , a third lens unit  6 , and an anti-slip component  7  disposed between the stationary barrel component  2  and the rotatable barrel component  3 . 
         [0006]    The stationary barrel component  2  is mounted to the base  1  through a plurality of screws  201  (only one is shown), and has an inner barrel surface  203  that surrounds an axis (K) and that defines an inner space  202 , an outer barrel surface  204  that is disposed opposite to the inner barrel surface  203  in radial directions relative to the axis (K), and a stop flange  206  that is disposed opposite to the base  1  along the axis (K) and that extends radially and outwardly from the outer barrel surface  204 . The stationary barrel component  2  is formed with a plurality of elongated slots  205  that extend through the inner and outer barrel surfaces  203 ,  204 , and that extend parallel to the axis (K). The rotatable barrel component  3  has an annular inner surface  301  that confronts the outer barrel surface  204  of the stationary barrel component  2 . The rotatable barrel component  3  is formed with a plurality of first cam slots  302  that correspond respectively in position to the elongated slots  205  in the stationary barrel component  2  and that extend around the axis (K), and a plurality of second cam slots  303  that are staggered relative to the first cam slots  302  and that also correspond respectively in position to the elongated slots  205 . The first lens unit  4  extends into the inner space  202  in the stationary barrel component  2 , is movable relative to the third lens unit  6  along the axis (K), and includes a first lens barrel  401  and a first lens  402  that is disposed in the first lens barrel  401 . The first lens barrel  401  has a plurality of first guide pins  403  that extend through the elongated slots  205  in the stationary barrel component  2 , and that are guided by the first cam slots  302  in the rotatable barrel component  3 . The second lens unit  5  is disposed in the inner space  202  in the stationary barrel component  2 , is also movable relative to the third lens unit  6  along the axis (K), and includes a second lens barrel  501  and a second lens  502  that is disposed in the second lens barrel  501 . The second lens barrel  501  has a plurality of second guide pins  503  that extend through the elongated slots  205  in the stationary barrel component  2 , and that are guided by the second cam slots  303  in the rotatable barrel component  3 . The anti-slip component  7 , such as an annular piece of flock paper, can position the rotatable barrel component  3  relative to the stationary barrel component  2  through friction. When the rotatable barrel component  3  rotates, it will drive the first and second lens units  4 ,  5  to move relative to the third lens unit  6 , thereby resulting in zoom adjustment for the conventional lens device. 
         [0007]    The rotatable barrel component  3  is positioned relative to the stationary barrel component  2  along the axis (K) through the base  1  and the stop flange  206  of the stationary barrel component  2 . In order for the rotatable barrel component  3  to rotate smoothly relative to the stationary barrel component  2 , there is a gap  8  formed between the stop flange  206  and a radial end face of the rotatable barrel component  3  that confronts the stop flange  206 . However, the gap  8  also provides room for the rotatable barrel component  3  to be movable along the axis (K) while rotating. Therefore, the first and second lens units  4 ,  5  driven by the rotatable barrel component  3  are not able to move precisely during zoom adjustment. Moreover, axial movement of the rotatable barrel component  3  while rotating will result in an image shaking effect. 
         [0008]    In addition, the anti-slip component  7  is disposed in order to increase the friction between the stationary barrel component  2  and the rotatable barrel component  3 , and to eliminate the image shaking effect. However, installation of the anti-slip component  7  results in a relatively long manufacturing time and a relatively high manufacturing cost. Moreover, since the anti-slip component  7  is made of flock paper, flocks thereof may fall off, thereby resulting in an unstable quality for the conventional lens device. 
       SUMMARY OF THE INVENTION 
       [0009]    Therefore, the object of the present invention is to provide a lens device having rotatable components that can be positioned along an axis and that are able to rotate smoothly relative to stationary components during zoom adjustment. 
         [0010]    Accordingly, a lens device of the present invention comprises a base unit, a rotatable barrel component, a press plate, and a lens unit. The base unit includes a base plate that has a positioning surface, and a stationary barrel component that is connected to the base plate, and that extends from the positioning surface of the base plate along an axis. The stationary barrel component has an inner barrel surface that surrounds the axis and that defines an inner space, and an outer barrel surface that is disposed opposite to the inner barrel surface in radial directions relative to the axis. The stationary barrel component is formed with a plurality of elongated slots that extend through the inner and outer barrel surfaces and that extend parallel to the axis. The rotatable barrel component is sleeved rotatably on the stationary barrel component, and has a first end face abutting against the positioning surface of the base plate, a second end face disposed opposite to the first end face along the axis, an annular inner surface interconnecting the first and second end faces and confronting the outer barrel surface of the stationary barrel component, and an annular outer surface disposed opposite to the annular inner surface in radial directions relative to the axis. The annular inner surface is formed with a plurality of cam slots that correspond respectively in position to the elongated slots in the stationary barrel component and that extend around the axis. The annular outer surface has a large diameter portion, a small diameter portion, and a shoulder portion interconnecting the large and small diameter portions. The press plate has at least one fixing end portion secured to the base unit, and a press section connected to the fixing end portion. The press section is elastically deformable relative to the fixing end portion and is disposed to abut against the shoulder portion of the annular outer surface of the rotatable barrel component. The lens unit extends into the inner space in the stationary barrel component of the base unit and is movable relative to the base unit along the axis. The lens unit includes a first lens barrel, and a first lens disposed in the first lens barrel. The first lens barrel has a plurality of guide pins that extend through the elongated slots in the stationary barrel component of the base unit, and that are guided by the cam slots in the rotatable barrel component. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
           [0012]      FIG. 1  is an assembled partly sectional view of a conventional lens device; 
           [0013]      FIG. 2  is an assembled perspective view of a preferred embodiment of a lens device according to the invention; 
           [0014]      FIG. 3  is a top view of the preferred embodiment; 
           [0015]      FIG. 4  is an assembled sectional view of the preferred embodiment taken along line  4 - 4  in  FIG. 3 ; 
           [0016]      FIG. 5  is an assembled sectional view of the preferred embodiment taken along line  5 - 5  in  FIG. 3 ; 
           [0017]      FIG. 6  is a side view of the preferred embodiment, illustrating a driving unit thereof; 
           [0018]      FIG. 7  is another side view of the preferred embodiment, illustrating how a press plate is connected to a base plate; and 
           [0019]      FIG. 8  is a partly exploded side view of the preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    As shown in  FIGS. 2 to 5 , the preferred embodiment of a lens device according to the present invention comprises a base unit  10 , a rotatable barrel component  20  sleeved rotatably on the base unit  10 , a driving unit  30  for driving rotation of the rotatable barrel component  20 , a press plate  40  for positioning the rotatable barrel component  20  relative to the base unit  10 , a first lens unit  50 , a second lens unit  60 , a third lens unit  70 , and a spring  80  disposed between first and second lens units  50 ,  60 . 
         [0021]    The base unit  10  includes a base plate  11  that has a positioning surface  111 , and a stationary barrel component  12  that is connected integrally to the base plate  11 , that extends from the positioning surface  111  of the base plate  11  along an axis (L), and that has an inner barrel surface  122  surrounding the axis (L) and defining an inner space  121 , and an outer barrel surface  123  disposed opposite to the inner barrel surface  122  in radial directions relative to the axis (L). The stationary barrel component  12  is formed with a plurality of first elongated slots  124  (see  FIG. 5 ) that extend through the inner and outer barrel surfaces  122 ,  123  and that extend parallel to the axis (L), and a plurality of second elongated slots  125  (see  FIG. 4 ) that extend through the inner and outer barrel surfaces  122 ,  123  and that are staggered relative to the first elongated slots  124 . The base unit  10  further includes an annular ornamental component  13  disposed opposite to the base plate  11  and engaging fittingly the stationary barrel component  12 . The annular ornamental component  13  includes a stop portion  131 , and a plurality of engaging portions  132  that extend from the stop portion  131  along the axis (L) to engage the stationary barrel component  12 . 
         [0022]    The rotatable barrel component  20  is sleeved rotatably on the stationary barrel component  12 , and has a first end face  21  that abuts against the positioning surface  111  of the base plate  11 , a second end face  22  that is disposed opposite to the first end face  21  along the axis (L), an annular inner surface  23  that interconnects the first and second end faces  21 ,  22  and that confronts the outer barrel surface  123  of the stationary barrel component  12 , and an annular outer surface  24  that is disposed opposite to the annular inner surface  23  in radial directions relative to the axis (L). The annular inner surface  23  is formed with a plurality of first cam slots  231  (see  FIG. 5 ) that correspond respectively in position to the first elongated slots  124  in the stationary barrel component  12  and that extend around the axis (L), and a plurality of second cam slots  232  (see  FIG. 4 ) that correspond respectively in position to the second elongated slots  125  and that are staggered relative to the first cam slots  231 . The annular outer surface  24  has a large diameter portion  241 , a small diameter portion  242 , and a shoulder portion  243  that interconnects the large and small diameter portions  241 ,  242 . In this embodiment, the large diameter portion  241  is formed with gear teeth  244 . 
         [0023]    The base unit  10  further includes a pair of positioning blocks  112  that protrude from the positioning surface  111  of the base plate  11  and that are disposed at two sides of the shoulder portion  243  of the annular outer surface  24  of the rotatable barrel component  20 , a pair of screws  113  that are fastened respectively to the positioning blocks  112 , and a pair of positioning pins  114 , each of which protrudes from a respective one of the positioning blocks  112  in a direction away from the positioning surface  111  of the base plate  11  and is disposed adjacent to a respective one of the screws  113 . 
         [0024]    The driving unit  30  is mounted to the base plate  11  of the base unit  10 , and includes a motor  31  and a transmission gear unit  32  driven by the motor  31  and meshing with the gear teeth  244  on the large diameter portion  241  of the annular outer surface  24  of the rotatable barrel component  20  (see  FIGS. 3 and 6 ). 
         [0025]    The press plate  40  is a leaf spring, and has a pair of fixing end portions  41  mounted respectively to the positioning blocks  112  of the base plate  11  of the base unit  10 , and a press section  42  interconnecting the fixing end portions  41 . With further reference to  FIGS. 7 and 8 , the press section  42  has a press surface  43  facing the shoulder portion  243  of the annular outer surface  24  of the rotatable barrel component  20 , a plurality of curved press protrusions  44  protruding from the press surface  43 , and a pair of pin holes  411  (see  FIG. 8 ) formed respectively in the fixing end portions  41  and through which the positioning pins  114  of the base unit  10  respectively extend. When the screws  113  of the base unit  10  are fastened respectively to the positioning blocks  112 , the screws  113  press the fixing end portions  41 , and the press section  42  elastically deforms relative to the fixing end portions  41  due to abutment of the press protrusions  44  against the shoulder portion  243  (see  FIG. 7 ). 
         [0026]    The first lens unit  50  extends into the inner space  121  in the stationary barrel component  12  of the base unit  10 , and is movable relative to the base unit  10  along the axis (L). The first lens unit  50  includes a first lens barrel  51  and a first lens  52  that is disposed in the first lens barrel  51 . The first lens barrel  51  has a plurality of first guide pins  511  (see  FIG. 5 ) that extend through the first elongated slots  124  in the stationary barrel component  12  of the base unit  10 , and that are guided by the first cam slots  231  in the rotatable barrel component  20 . 
         [0027]    In this embodiment, the second lens unit  60  is disposed in the inner space  121  in the stationary barrel component  12  of the base unit  10 , and is movable relative to the base unit  10  along the axis (L). The second lens unit  60  includes a second lens barrel  61  and a second lens  62  that is disposed in the second lens barrel  61  and that is optically aligned with the first lens  52  of the first lens unit  50 . The second lens barrel  61  has a plurality of second guide pins  611  (see  FIG. 4 ) that extend through the second elongated slots  125  in the stationary barrel component  12  of the base unit  10 , and that are guided by the second cam slots  232  in the rotatable barrel component  20 . 
         [0028]    In this embodiment, the third lens unit  70  is disposed in the inner space  121  in the stationary barrel component  12  of the base unit  10 , and includes a supporting seat  71  that is secured on the base plate  11  of the base unit  10 , and a third lens  72  that is disposed in the supporting seat  71  and that is optically aligned with the first lens  52  of the first lens unit  50  and the second lens  62  of the second lens unit  60 . The second lens  62  is disposed between the first and third lenses  52 ,  72  along the axis (L). 
         [0029]    In this embodiment, the spring  80  is a compression spring with two opposite ends abutting against the first lens barrel  51  of the first lens unit  50  and the second lens barrel  61  of the second lens unit  60 , respectively. The spring  80  forces the first guide pins  511  of the first lens unit  50  and the second guide pins  611  of the second lens unit  60  to abut respectively against the first and second cam slots  231 ,  232  in the rotatable barrel component  20 , thereby preventing the optical axes of the first and second lens units  50 ,  60  from tilting. 
         [0030]    As shown in  FIGS. 2 ,  4 , and  5 , the rotatable barrel component  20  is disposed such that the first end face  21  thereof abuts against the positioning surface  111  of the base plate  11  of the base unit  10 , and the press plate  40  elastically deforms relative to the fixing end portions  41  of the press plate  40  due to abutment of the press protrusions  44  of the press plate  40  against the shoulder portion  243  of the annular outer surface  24  of the rotatable barrel component  20 . Therefore, the large diameter portion  241  of the annular outer surface  24  of the rotatable barrel component  20  is positioned between the positioning surface  111  and the press plate  40  and is unable to move along the axis (L). Moreover, the first and second lens units  40 ,  50  driven by the rotatable barrel component  20  can move precisely during zoom adjustment, and the drawback of image shaking can be eliminated effectively. Furthermore, since the press plate  40  is disposed to abut elastically against the shoulder portion  243  of the annular outer surface  24  of the rotatable barrel component  20 , possible slipping between the rotatable barrel component  20  and the stationary barrel component  12  can be eliminated effectively. 
         [0031]    Compared to the aforementioned conventional lens device, the disposition of the press plate  40  is simpler, thereby resulting in a lower manufacturing cost. In addition, it is easy to adjust the friction between the press section  42  of the press plate  40  and the shoulder portion  243  of the annular outer surface  24  of the rotatable barrel component  20  by loosening or tightening the screws  113  of the base unit  10 . 
         [0032]    It should be noted that, while this invention is exemplified using first, second, and third lens units  50 ,  60 ,  70 , only one lens unit  50  may be employed in other embodiments of this invention, such as in lower end lens devices. Moreover, while in this preferred embodiment, the rotatable barrel component  20  is driven to rotate through a gear configuration, the rotatable barrel component  20  can be driven to rotate through a cam structure, or even by manual adjustment in other embodiments of this invention. 
         [0033]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.