Abstract:
A lens arrangement includes two lenses. Each lens includes an optical portion having an optical axis, a non-optical portion surrounding the optical portion, and an engagement portion extending along and inclining relative to the optical axis from the non-optical portion. The engagement portions of the lenses are engaged with each other and an included angle is defined between the engagement portions. One of the lenses includes an elastic element which can be flexibly deformed relative to the other lens.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    This present disclosure relates to lenses, and particularly, to a lens arrangement and a lens module using same. 
         [0003]    2. Description of Related Art 
         [0004]    Engaging lens modules often include a first annulus protruding from a first lens and a second annulus protruding from a second lens. The inner diameter of the first annulus is equal to the outer diameter of the second annulus, thus, the second annulus can be precisely engaged in the first annulus. Injection molding is often used to form the first annulus and the second annulus. However, it is difficult to precisely mold such annuluses, and an extremely high molding pressure is required to mold the annuluses. This causes a plurality of angle deformations that can interfere with the cooperation of the first annulus with the second annulus. 
         [0005]    Therefore, it is desirable to provide a lens arrangement and a lens module, which can overcome or at least alleviate the above-mentioned limitations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a cross-sectional, exploded view of a lens arrangement, according to an exemplary embodiment. 
           [0007]      FIG. 2  is a cross-sectional, assembled view of the lens arrangement of  FIG. 1 . 
           [0008]      FIG. 3  is an enlarged view of portion III of  FIG. 2 . 
           [0009]      FIG. 4  is an assembled, cross-sectional view of a lens module, according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1 , a lens arrangement  100 , according to an exemplary embodiment, includes a first lens  10  and a second lens  20 . 
         [0011]    The first lens  10  and the second lens  20  can be plastic or glass lenses. In the present disclosure, both of the first lens  10  and the second lens  20  are plastic lenses. 
         [0012]    The first lens  10  includes a first non-optical portion  16  surrounding a first optical portion  14 . The first optical portion  14  is configured for refracting incident light rays and forming corresponding optical images, and defines a first optical axis  12 . The first non-optical portion  16  is configured for engaging with the second lens  20 . The first lens  10  further includes a first engagement portion  18  protruding along a direction substantially parallel to the first optical axis  12 . The first engagement portion  18  is substantially annular and symmetrical about the first optical axis  12 . The first engagement portion  18  includes an inner circumferential engagement surface  18   s . In the present disclosure, the inner circumferential engagement surface  18   s  inclines radially outwards from the first non-optical portion  16 . 
         [0013]    The second lens  20  includes a second non-optical portion  26  surrounding a second optical portion  24 . The second optical portion  24  is configured for refracting incident light rays and forming corresponding optical images, and defines a second optical axis  22 . The second non-optical portion  26  is configured for engaging with the first lens  10 . The second lens  20  also includes a second engagement portion  28  protruding along a direction parallel to the second optical axis  22 . The second engagement portion  28  is substantially annular and symmetrical about the second optical axis  22 . The second engagement portion  28  includes an outer circumferential engagement surface  28   s  for engaging with the inner circumferential engagement surface  18   s . In the present disclosure, the outer circumferential engagement surface  28   s  radially inclines inwards from the second non-optical portion  26 . 
         [0014]    In alternative embodiments, the geometrical shape of the cross section of the engagement portion (the first engagement portion  18  and the second engagement portion  28 ) of each of the lenses (the first lens  10  and the second lens  20 ) along the optical axis is selected from the group consisting of a rectangle, a triangle, and a right-angled trapezoid. 
         [0015]    Referring to  FIG. 3 , an example of an error in precision of molding is shown. A first included angle α between the inner circumferential engagement surface  18   s  and the first optical axis  12  is greater than a second included angle β between the outer circumferential engagement surface  28   s  and the second optical axis  22 . As such, when the first lens  10  is engaged with the second lens  20 , a third included angle θ equal to a difference between the first included angle α and the second included angle β is defined between the inner circumferential engagement surface  18   s  and the outer circumferential engagement surface  28   s . The following explains in detail how the error is overcome using the lens arrangement  100 . 
         [0016]    The smallest diameter of the inner circumferential engagement surface  18   s  is equal to or less than the largest diameter of the outer circumferential engagement surface  28   s , to ensure the first lens  10  can engage with the second lens  20 . 
         [0017]    The inner circumferential engagement surface  18   s  defines a number of grooves  181  equidistantly arranged along a circumferential direction thereof. 
         [0018]    An elastic element  30  is fixed in each groove  181  and can be flexibly deformed along a direction perpendicular to the bottom of the groove  181 . In detail, the elastic element  30  includes a spring  31  and a shim  33  fixed on a distal end of the spring  31 . In the present disclosure, the spring  31  is adhered to the bottom of the groove  181  and the shim  33  is adhered to the spring  31 . A free length of the spring  31  is longer than a distance between the inner circumferential engagement surface  18   s  and the bottom. In order to avoid scratching the second lens  20 , the elastic element  30  is made either of a soft material, a very flexible material, or both. 
         [0019]    Furthermore, an aperture stop  40  is disposed between the first engagement portion  18  and the second engagement portion  28  for imaging. 
         [0020]    Upon assembly, the first engagement portion  18  slides along the second engagement portion  28  until the first engagement portion  18  is tightly engaged with the second engagement portion  28 . Thus, the first lens  10  and the second lens  20  are tightly engaged with each other via friction between the inner circumferential engagement surface  18   s  and the outer circumferential engagement surface  28   s . The elastic element  30  is pressed by the second lens  20  to resist the first lens  10  with a resilience force. The first optical axis  12  is superposed on the second optical axis  22 , constituting a common optical axis of the lens arrangement  100 . As such, an alignment of the first lens  10  and the second lens  20  is achieved. 
         [0021]    Thus, the third included angle θ defined between the first lens  10  and the second lens  20 , due to angle deformation of the first engagement portion  18  and/or the second engagement portion  28  during molding is counteracted. Furthermore, due to the resilient force of the elastic element  30 , the first lens  10  and the second lens  20  can be engaged with each other more tightly. 
         [0022]    It should be noted that the lens arrangement  100  can include more than two lenses. Each two adjacent lenses are engaged in a similar way as the first lens  10  and the second lens  20 . In addition, the grooves  181  can also be defined in the outer circumferential engagement surface  28   s  while the elastic element  30  is fixed thereto. 
         [0023]    Further, cross sections of the first engagement portion  18  along the first optical axis  12  and the second engagement portion  28  along the second optical axis  22  can be rectangular, triangular, or right-angled trapezoid. 
         [0024]    Referring to  FIG. 4 , a lens module  200 , according to an exemplary embodiment, includes the lens arrangement  100  and a lens barrel  300 . The lens barrel  300  holds the lens arrangement  100 . 
         [0025]    While various exemplary and preferred embodiments have been described, it is to be understood that the disclosure is not limited thereto. Various modifications and similar arrangements can also be covered as would be apparent to those skilled in the art. 
         [0026]    Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.