Abstract:
A photoelectric conversion device includes a circuit board, a light emitting module, a light receiving module, and an optical coupling lens. Two protrusions apart from each other extend from the circuit board. The light emitting module and the light receiving module are mounted on the circuit board and apart from each other. The optical coupling lens includes an oblique reflection surface and a recess having a bottom surface parallel to the circuit board. Two distanced posts perpendicularly extend from the bottom surface and engage with the centers of the protrusions upon assembly to ensure automatic and alignment of the light emitting module with the first converging lens, and alignment of the light receiving module with the second converging lens.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to photoelectric conversion devices. 
         [0003]    2. Description of Related Art 
         [0004]    A photoelectric conversion device includes a circuit board, a light emitting module, a light receiving module, and an optical coupling lens. The light emitting module and the light receiving module are mounted on the circuit board. The optical coupling lens includes a first converging lens and a second converging lens. The first converging lens is intended to be aligned with and optically coupled with the light emitting module, and the second converging lens is intended to be aligned with and optically coupled with the light receiving module. Light emitted from the light emitting module passes through the first converging lens, and light from the second converging lens reaches the light receiving module. The transmission efficiency of light depends on a precise alignment between the first converging lens and the light emitting module and between the second converging lens and the light receiving module. In particular, the higher the alignment precision is, the higher is the transmission efficiency. Therefore, it is important to design a photoelectric conversion device having an automatically precise alignment between the first converging lens and the light emitting module and between the second converging lens and the light receiving module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a schematic, isometric view of a photoelectric conversion device, according to an exemplary embodiment. 
           [0006]      FIG. 2  is a partial, schematic, isometric view of the photoelectric conversion device of  FIG. 1 . 
           [0007]      FIG. 3  is a sectional view of the photoelectric conversion device of  FIG. 1 , taken along the line III-III of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    Referring to  FIG. 1 , a photoelectric conversion device  100 , according to an exemplary embodiment, includes a circuit board  10 , a light emitting module  20 , a light receiving module  30 , and an optical coupling lens  40 . 
         [0009]    The circuit board  10  includes a lower surface  12  and an upper surface  14 . The lower surface  12  and the upper surface  14  are positioned at opposite sides of the circuit board  10 , and the lower surface  12  is parallel to the upper surface  14 . Two protrusions  16  perpendicularly extend from the upper surface  14 . In this embodiment, the protrusions  16  are cylindrical. That is, if the protrusions  16  are cut in a plane parallel to the upper surface  14 , the cross-section of each of the protrusions  16  is perfectly circular. 
         [0010]    The light emitting module  20  and the light receiving module  30  are mounted on the upper surface  14  and electrically connected to the circuit board  10 . In detail, the light emitting module  20 , the light receiving module  30 , and the two protrusions  16  are arranged in a straight line, and the two protrusions  16  are located between the light emitting module  20  and the light receiving module  30 . That is, centers of the light emitting module  20 , of the light receiving module  30 , and of the two protrusions  16  are arranged in a straight line. In this embodiment, the light emitting module  20  is a vertical cavity surface emitting laser (VCSEL) diode and is configured for emitting light. The light receiving module  30  is a photo diode and is configured for receiving light. 
         [0011]    Referring to  FIGS. 1-2 , the optical coupling lens  40  includes a transparent body portion  42 , a first converging lens  43 , a second converging lens  44 , a third converging lens  45 , a fourth converging lens  46 , two posts  48 , and two supports  49 . 
         [0012]    The body portion  42  is a straight triangular prism and includes a light incident surface  422 , a reflection surface  424 , and a light output surface  426 . The light incident surface  422  is parallel to the upper surface  14 . The light output surface  426  perpendicularly extends from the light incident surface  422 . The reflection surface  424  is obliquely interconnected between the light incident surface  422  and the light output surface  426 . In this embodiment, an included angle between the light incident surface  422  and the reflection surface  424  is about  45  degrees, and an included angle between the light output surface  426  and the reflection surface  424  is about  45  degrees. A recess  420  is defined in the reflection surface  424 . The recess  420  includes a bottom surface  421  parallel to the light incident surface  422  and the upper surface  14 . 
         [0013]    The first converging lens  43  and the second converging lens  44  are formed on the light incident surface  422  and arranged apart from each other. The third converging lens  45  and the fourth converging lens  46  are formed on the light output surface  426  and arranged apart from each other. The two posts  48  are located on the bottom surface  421  and arranged apart from each other. In this embodiment, the two posts  48  are cylindrical. That is, if the posts  48  are cut in a plane parallel to the upper surface  14 , the cross-section of each of the posts  48  is perfectly circular. The two supports  49  perpendicularly extend from the light incident surface  422  and are arranged apart from each other. In this embodiment, the first converging lens  43 , the second converging lens  44 , and the two supports  49  are arranged in a straight line, and the first converging lens  43  and the second converging lens  44  are located between the two supports  49 . 
         [0014]    The first converging lens  43 , the second converging lens  44 , the protrusions  16 , the light emitting module  20 , and the light receiving module  30  can be observed along a direction perpendicular to and above the bottom surface  421  because the body portion  42  is transparent. The first converging lens  43 , the second converging lens  44 , and the two posts  48  are arranged in a straight line, and the two posts  48  are located between the first converging lens  43  and the second converging lens  44 . 
         [0015]    The locational relationship between the first converging lens  43  and the two posts  48  is substantially the same as that of the light emitting module  20  and the two protrusions  16 , and the locational relationship between the second converging lens  44  and the two posts  48  is substantially the same as that of the light receiving module  30  and the two protrusions  16 . In detail, the distance between a center of the first converging lens  43  and a center of each of the posts  48  is equal to the distance between a center of the light emitting module  20  and a center of each of the protrusions  16 . The distance between a center of the second converging lens  44  and a center of each of the posts  48  is equal to the distance between a center of the light receiving module  30  and a center of each of the protrusions  16 . The diameter of each of the posts  48  is substantially equal to the diameter of each of the protrusions  16 , and the diameters of each of the posts  48  exceeds the diameters of the first converging lens  43  and the second converging lens  44 . 
         [0016]    In alternative embodiments, the posts  48  may be may be triangular, rectangular, or elliptic and the cross-section of each of the protrusions  16  may accordingly be triangular, rectangular, or elliptic, the dimensions of each of the posts  48  always being the same as the dimensions of each of the protrusions  16 . 
         [0017]    When the photoelectric conversion device  100  is assembled, the optical coupling lens  40  is adhered onto the upper surface  14  with adhesive. In detail, first, the optical coupling lens  40  is placed on the upper surface  14 . In this situation, the two supports  49  abut the upper surface  14 . Second, the optical coupling lens  40  is moved until the centers of the protrusions  16  are aligned with the centers of the posts  48 , while the location of the protrusions  16  can be observed along a direction perpendicular to and above the bottom surface  421 . In this situation, where the protrusions  16  completely coincide with the posts  48 , the light emitting module  20  is perfectly aligned with the first converging lens  43 , and the light receiving module  30  is thus perfectly aligned with the second converging lens  44 . Third, glue is applied to sidewalls of the supports  49  to fix the optical coupling lens  40  on the upper surface  14 . Thereby, the photoelectric conversion device  100  has a high alignment precision and thus a high transmission efficiency of light. 
         [0018]    Referring to  FIG. 3 , when in use, electrical power is applied to the light emitting module  20  and the light receiving module  30  through the circuit board  10 , thus light beams emitted from the light emitting module  20  enter into the first converging lens  43  and become parallel, and are then reflected about 90 degrees toward the light output surface  426  by the reflection surface  424 , and finally exit from the light output surface  426 . Accordingly, parallel light beams passing through the light output surface  426  are reflected about  90  degrees toward the second converging lens  44 , and are finally converged into the light receiving module  30  by the second converging lens  44 . 
         [0019]    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 the matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.