Abstract:
An exemplary lens module ( 20 ) includes a lens barrel ( 5 ), a focusing mechanism ( 7 ), a resilient member ( 9 ), and a bottom seat ( 6 ). The lens barrel is mounted with a lens ( 517 ) therein. The lens barrel is axially movable relative to the bottom seat due to a rotation of the focusing mechanism and the force generated by the resilient member. Such an axial movement, in turn, would change a position of the lens relative to the bottom seat.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to lens modules and, more particularly, to a lens module with a focusing mechanism configured (i.e., structured and arranged) for use in an optical device, such as a microscope, a camera module, a digital camera module used in a portable electronic device, or the like. 
         [0003]    2. Description of Related Art 
         [0004]    With the ongoing development of microcircuitry and multimedia technologies, digital cameras are now in widespread use. High-end portable electronic devices, such as mobile phones and personal digital assistants (PDAs), are being developed to be increasingly multi-functional. Many of these portable electronic devices are now equipped with a digital camera module. These electronic devices enable consumers to enjoy capturing digital pictures anytime and anywhere. At the same time, the desire/need for improved digital picture quality has become greater and greater. 
         [0005]    In a typical camera module, a lens module is a very important element in producing high quality pictures. Generally, a camera module includes a lens module and an image sensing module. Optical image signals are focused by the lens module onto the image sensing module. The image sensing module transforms the optical image signals into electronic image signals. When a distance between the lens module and the image sensing module is adjusted, the definition of the optical image signals received by the image sensing module is also changed. Focusing mechanisms are widely used in camera modules (both digital and film-based) for creating high quality photos. 
         [0006]    In a typical focusing mechanism-equipped lens module, the focusing mechanism generally includes some driving elements such as gearings and motors. When the lens module is used to take photos, the focusing mechanism moves optical components, such as the lens module and/or the image sensing module, to an appropriate position using the drivers. However, the structure of the focusing mechanism is often complicated and is likely to undergo wear and tear during long-term operation, and the precision of the focusing mechanism tends to be reduced as a result of such wear and tear. 
         [0007]    Therefore, a new lens modules is desired in order to overcome the above-described shortcomings. 
       SUMMARY 
       [0008]    In one embodiment thereof, a lens module includes a lens barrel, a focusing mechanism, and a bottom seat. The lens barrel includes at least one lens mounted therein. The focusing mechanism is configured for facilitating a selectable axially movement of the lens barrel and is rotatable relative to the lens barrel. The focusing mechanism is configured as a cam-linear mechanism. The lens barrel is axially movable relative to the bottom seat due to a rotation of the focusing mechanism, the rotation thereby facilitating a change in a position of the at least one lens relative to the bottom seat. 
         [0009]    Other advantages and novel features of the embodiments will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the present lens module can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the lens module and its potential applications. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is an assembled, isometric view of a camera module having a lens module with a focusing mechanism, in accordance with a preferred embodiment; 
           [0012]      FIG. 2  is an exploded, isometric view of the camera module in  FIG. 1 ; 
           [0013]      FIG. 3  is similar to  FIG. 2  but viewed from another aspect; and 
           [0014]      FIG. 4  is a cross-sectional view along line IV-IV in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0015]    Referring now to the drawings in detail,  FIG. 1  shows a camera module  10  of a preferred embodiment. The camera module  10  includes a lens module  20  with focusing mechanism and an image sensing module  8 . The lens module  20 , in the illustrated embodiment, is used to concentrate image light traveling incident to the lens module  20  onto the image sensing module  8  to capture an image. While the lens module  20  is shown incorporated into the camera module  10 , it is to be understood that the lens module  20  or obvious variations thereof may prove useful in other work environments (e.g., in microscopes). 
         [0016]    Also further referring to  FIG. 2  as well as  FIG. 1 , the lens module  20  includes a lens barrel  5 , a bottom seat  6 , a focusing mechanism  7 , and a resilient member  9 . The lens barrel  5  is movably mounted in the bottom seat  6 . The focusing mechanism  7  is mounted in the bottom seat  6  and engages with the lens barrel  5 . 
         [0017]    Additionally referring to  FIGS. 3-4 , the lens barrel  5  has a substantially cylindrical body  51  and a cover  53 . The cover  53  is mounted to one end of the body  51  and defines an opening  531  in a center thereof. The opening  531  is configured for allowing image light to travel therethrough. A plurality of lenses  517  is advantageously mounted in the body  51  for concentrating image light onto the image sensing module  8 , although it is understood that a simple one-lens unit could be employed and be within the scope of the present lens module. A pair of guiding rails  511  is formed on a periphery of the body  51  and extends along an axial direction of the body  51 . The two guiding rails  511  are separated from each other by an angle of about 180 degrees. A displacement measuring module  513  is formed directly on the periphery of the body  51  and is located between the two guiding rails  511 . A pin  515  is formed on the periphery of the body  51 , in contact therewith, and faces away from the displacement measuring module  513 . 
         [0018]    The bottom seat  6  includes a lens seat  61  and a bottom board  63 . The lens seat  61  is substantially cylindrical in shape. An inner diameter of the lens seat  61  is substantially equal to an outer diameter of the body  51  of the lens barrel  5  so that the lens barrel  5  can be movable in the lens seat  61  while ensuring the alignment of the lens barrel  5  relative thereto. A side hole  611  is defined through the lens seat  61 . A pair of guiding grooves  613  is defined in an inner wall of the lens seat  61 . The guiding grooves  613  are configured for movably receiving the guiding rails  511  of the lens barrel  51  so that the lens barrel  5  can be essentially only axially movable (i.e., limited to a single degree of freedom) relative to the lens seat  61 . The bottom board  63  is mounted to and, thereby, adjacent the image sensing module  8 . 
         [0019]    A receiving groove  615  is further defined directly in the inner wall of the lens seat  61  and between the two guiding grooves  613 . The receiving groove  615  is configured for receiving the displacement measuring module  513  therewithin, allowing the displacement measuring module  513  to measure the displacement between the lens barrel  5  and the lens seat  61 . It is noted that the interaction of the receiving groove  615  and the displacement measuring module  513  also serves to axially limit the movement of the lens barrel  5  relative to the lens seat  61 . 
         [0020]    The lens seat  61  is mounted on the bottom board  63 . The bottom board  63  is rectangular in shape and defines a through hole  631  through a center thereof. A circular receiving slot  633  is defined directly in a top portion of the bottom board  63  and around the through hole  631 . It is because of the through hole  631  and opening  531  that light is able to travel through the lenses  517  and to reach the image sensing module  8 . 
         [0021]    The focusing mechanism  7  includes a motor  71  and a driving pole  73 . The motor  71  can, for example, be a step motor or any other motor facilitating highly controlled motion. The driving pole  73  can be rotated by use of the motor  71 . A cam slot  733  is defined in one end of the driving pole  73 , the cam slot  733  advantageously being elliptical. However, it is to be understood that other cam slot shapes could be chosen to permit for more complex focusing abilities. The driving pole  73  is configured for receipt in the side hole  611  of the lens seat  61 . 
         [0022]    The resilient member  9  is advantageously made of metal or, potentially, a resilient polymer and is advantageously spiral-shaped (i.e., a coil spring). A diameter of the resilient member  9  is larger than an inner diameter of the lens barrel  5  and less than or equal to the inner diameter of the lens seat  61 . One end of the resilient member  9  is configured/sized to be fittingly received in the receiving slot  633 . 
         [0023]    The image sensing module  8  includes a flexible circuit board  83  and an image sensor member  81 . The flexible circuit board  83  is electrically connected to the image sensor member  81 . The image sensor member  81  is configured for receipt in the through hole  631  of the bottom board  63 . The image sensor member  81  transforms image light signals into electronic signals. 
         [0024]    In assembly, the set of lenses  517  is mounted in the body  51  of the lens barrel  5 . One end of the resilient member  9  is placed in the receiving slot  633  of the bottom board  63 . The lens barrel  5  is mounted in the lens seat  61  and on the other opposite end of the resilient member  9 . The guiding rails  511  of the lens barrel  51  engage in the guiding grooves  613  of the lens seat  61 . The displacement measuring module  513  is received in receiving groove  615  of the lens seat  61 . The focusing mechanism  7  is mounted to the bottom seat  6 . The driving pole  73  is received in the side hole  611  of the lens seat  61 . The pin  515  is received in the slot  733  of the driving pole  73 . The image sensor member  81  of image sensing module  8  is received in the through hole  631  of the bottom board  63 . Thus, the camera module  10  is completely assembled, as represented in  FIGS. 1 and 4 . 
         [0025]    In use, when the camera module  10  is used to take photos of objects, the motor  71  of the focusing mechanism  7  is operated to drive the driving pole  73  to rotate. The rotation of the driving pole  73  and the force generated by the resilient member  9  results in axial movement of the pin  515  and the lens barrel  5 , relative to the lens seat  61 . Specifically, the driving pole  73  and the pin  515  together essentially act as a cam-linear linkage, with the resilient member  9  always pushing the pin  515  to its highest point of travel possible within the interior of the driving pole  73 . The highest point of travel depends essentially solely on the angle of displacement of the driving pole  73  (as controlled by the motor  71 ), since the pin  515  itself cannot move angularly (i.e., the lens barrel  5  being limited solely to axial movement). The displacement measuring module  513  measures the displacement between the lens barrel  5  and the lens seat  61  and transfers the displacement information to the motor  71  or a user. When the lens barrel  5  is located in a desired position, the motor  71  is stopped. 
         [0026]    It is to be understood that the resilient member  9  may alternatively be made of another material (e.g., plastic or rubber). The resilient member  9  may also have a different configuration, for example, a leaf spring or a resilient cylinder. The receiving slot  633  may be omitted and the resilient member  9  may be mounted (e.g., via an adhesive or a solder) on the bottom board  63 . The resilient member  9  may be omitted. Alternatively, the guiding rails may be formed on the inner wall of the lens seat  61 , and, accordingly, the guiding grooves may be defined in the lens barrel  5 . 
         [0027]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.