Abstract:
Scan modules are provided. A scan module includes a carrier, a first lens fixed to the carrier, a second lens movably connected to the carrier, and an optical sensor fixed to the carrier. The first lens detects light from a scan area through the first lens to the optical sensor along an optical path when the second lens is in a first position and out of the optical path. The second lens intervenes and alters the optical path when in a second position.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates in general to scanners and in particular to scanners capable of different resolutions. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, scan scope of a conventional scanner corresponds to the dimensions of frequently scanned documents. When scan scope and optical focal length are determined, resolution of the scanner is fixed. As conventional scanners usually scan documents of regular sizes, they may perform poor pixel utilization and inadequate resolution when scanning small size documents, such as positive or negative films. 
         [0005]    Referring to  FIG. 1 , a conventional CCD scanner  10  includes a lens  1  and a CCD  2 , wherein optical magnification of the scanner  10  is fixed. When scanning a small document  3 , only a small region of the CCD  2  is occupied (even less than ¼ of the CCD  2 ) by the projected image of the document  3 , as shown in  FIG. 1 , thus leading to poor resolution and inefficient pixel utilization of the CCD  2 . 
         [0006]    While redesigning the lens and the CCD is a conventional solution to improve resolution when scanning small documents, it inevitably increases production cost and may be unnecessary for scanning documents of regular sizes. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    Scan modules are provided. A scan module includes a carrier, a first lens fixed to the carrier, a second lens movably connected to the carrier, and an optical sensor fixed to the carrier. The first lens detects light from a scan area through the first lens to the optical sensor along an optical path when the second lens is in a first position and out of the optical path. The second lens intervenes and alters the optical path when in a second position. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a perspective diagram of a conventional CCD scanner when scanning a small document; 
           [0010]      FIGS. 2   a  and  2   b  are perspective diagrams of optical paths of a scan module of this invention; 
           [0011]      FIG. 3  is a perspective diagram of a scanner; 
           [0012]      FIG. 4   a  is a perspective diagram of a scan module; 
           [0013]      FIG. 4   b  is a perspective diagram of the scan module in  FIG. 4   a  with a cover removed; 
           [0014]      FIG. 4   c  is an enlarged view of portion A in  FIG. 4   b;    
           [0015]      FIG. 4   d  is a perspective diagram of a second lens; 
           [0016]      FIG. 5   a  is a perspective diagram of optical paths of a scan module when a second lens is in a first position; 
           [0017]      FIG. 5   b  is a perspective diagram of optical paths of a scan module when a second lens is in a second position; 
           [0018]      FIGS. 6   a  and  6   b  are perspective diagrams of a scan module utilizing an embodiment of a driving mechanism; 
           [0019]      FIGS. 7   a  and  7   b  are perspective diagrams of a scan module utilizing another embodiment of a driving mechanism; 
           [0020]      FIGS. 8   a  and  8   b  are perspective diagrams of a scan module utilizing another embodiment of a driving mechanism; 
           [0021]      FIG. 8   c  is a perspective diagram of a linkage structure; 
           [0022]      FIG. 9   a  is a side view of a scan module when, a linkage structure is in a first state; 
           [0023]      FIG. 9   b  is a side view of a scan module when a linkage structure is in a second state; and 
           [0024]      FIG. 9   c  is a top view of the linkage structure in  FIG. 9   b.    
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The invention provides a scan module including a primary lens and a movable auxiliary lens for scanning regular documents or small documents. When scanning regular documents, the primary lens is applied. When scanning small documents, the auxiliary lens is optically incorporated with the primary lens to achieve higher scan resolution. 
         [0026]    Referring to  FIGS. 2   a  and  2   b , an embodiment of a scan module includes a primary lens  21  and a movable auxiliary lens  23 . When scanning a regular document, as shown in  FIG. 2   a , the scan module is in a first mode, wherein an optical principal surface  22  of the primary lens  21  defines a first focal length f. When scanning a small document, as shown in  FIG. 2   b , the scan module is in a second mode, wherein the auxiliary lens  23  is aligned and optically incorporated with the primary lens  21 , such that widths of conjugate scanning rays are narrowed to facilitate higher optical magnification. In  FIG. 2   b , a second focal length f′ longer than the first focal length f is defined by a new optical principal surface  24 , wherein displacement between the optical principal surfaces  22  and  24  is ΔP=(f′−f). The scan module can be switched between the first and second modes to scan regular documents or small documents by arrangement of the primary lens  21  and the movable auxiliary lens  23 . 
         [0027]    Referring to  FIG. 3 , an embodiment of a scanner  100  comprises a housing  101  and a scan module  102 . The housing  101  has a transparent plate  103  with an object  104  disposed thereon. The scan module  102  is disposed in the housing  101  and movable along Z axis, as the arrows  601  and  602  indicate in  FIG. 3 . 
         [0028]    As shown in  FIG. 3 , the scan module  102  comprises an optical sensor  106  defining a scan area  116 . In this embodiment, the scan area  116  is substantially above the transparent plate  103 . When scanning the object  104 , the scan module  102  moves along the direction  601 , such that the object  104  is located within the scan area  116  to be scanned clearly. 
         [0029]    Referring to  FIGS. 4   a  and  4   b , the scan module  102  primarily includes a carrier  105 , an optical sensor  106 , a first lens  107 , a movable second lens  108 , a positioning block  110  and a driving mechanism (not shown) for impelling the second lens  108 . As shown in  FIG. 4   a , the carrier  105  comprises a cover  117  and a main body  118 . The optical sensor  106 , such as a CCD, is disposed in the main body  118  of the carrier  105 . The first lens  107  is fixed to the main body  118  and located between the scan area  116  and the optical sensor  106 . 
         [0030]    As shown in  FIG. 4   b , the second lens  108  is connected to the main body  118  and movable between a first position  200  and a second position  201 . In this embodiment, the main body  118  has a rail  111 , and the second lens  108  has a slider  112  sliding along the rail  111 . 
         [0031]    Referring to  FIGS. 4   c  and  4   d , the positioning block  110  fixed to the main body  118  has a recess  113 , and correspondingly, the second lens  108  has a nub  114  joined in the recess  113  when the second lens  108  moves to the second position  201 , as shown in  FIG. 4   c , such that the second lens  108  is held in the second position  201 . Furthermore, the driving mechanism (not shown) is disposed in the main body  118  to impel the second lens  108  between the first and second positions  200  and  201 . 
         [0032]      FIG. 5   a  depicts optical paths  701  when the second lens  108  is in the first position  200  for scanning the object  104 . As shown in  FIG. 5   a , when scanning the object  104 , the first lens  107  and the optical sensor  106  of the scan module  102  are aligned with the object  104 , such that the object  104  is located within the scan area  116 . Hence, the optical sensor  106  detects light from the scan area  116  through the first lens  107  along the light paths  701 , and a first image  120  is formed on a sensitive area  119  of the optical sensor  106 , corresponding to the object  104  within the scan area  116 . Specifically, the second lens  108  is out of the light paths  701 , that is, light paths  701  from the scan area  116  to the optical sensor  106  are independent from the second lens  108 . 
         [0033]      FIG. 5   b  depicts new optical paths  702  when the second lens  108  moves to the second position  201  for scanning the object  104 . As shown in  FIG. 5   b , when the second lens  108  moves to the second position  201  in front of the first lens  107 , the first and second lenses  108  are centrally aligned and optically incorporated with each other, to produce new optical paths  702 , different from the first optical paths  701  shown in  FIG. 5   a . Here, the optical sensor  106  detects light from the scan area  116  through the first and second lenses  107  and  108  along the light paths  702 , such that a second image  121  is formed on the sensitive area  119  of the optical sensor  106 , corresponding to the object  104  within the scan area  116 . 
         [0034]    Comparing  FIG. 5   b  with  FIG. 5   a , the width L 2  of the second image  121  exceeds the width L 1  of the first image  120 . Namely, dimensions of the optical sensor  106  occupied by the second image  121  exceed those of the first image  120 , increasing the pixel utilization of the optical sensor  106 , such that the optical magnification increased and the resolution improved. 
         [0035]    Embodiments of the driving mechanism for moving the second lens  108  between the first and second positions  200  and  201  are disclosed. 
         [0036]      FIG. 6   a  is a perspective diagram of the scan module  102  when the second lens  108  is in the first position  200  with the cover  117  removed. In this embodiment, the scan module  102  has a driving mechanism  109   a  including an electromagnet  300  disposed on the main body  118  and a magnet  301  fixed to the second lens  108 . The second lens  108  is moved along the rail  111  by magnetic attraction or repulsion between the electromagnet  300  and the magnet  301 . 
         [0037]    When the electromagnet  300  produces a first magnetic polarity to attract the magnet  301 , the second lens  108  is moved with the magnet  301  to the first position  200 , as shown in  FIG. 6   a . When the electromagnet  300  produces a second magnetic polarity to repulse the magnet  301 , as shown in  FIG. 6   b , the second lens  108  is moved with the magnet  301  from the first position  200  to the second position  201 . 
         [0038]    Referring to  FIGS. 7   a  and  7   b , another embodiment of a driving mechanism  109   b  primarily includes a gear  400 , a motor  401  disposed in the main body  118 , and a rack  402  fixed to the second lens  108 . In this embodiment, the gear  400  is connected to the motor  401  and engaged with the rack  402 . When the motor  401  rotates the gear  400 , the rack  402  is driven to move the second lens  108  between the first and second positions  200  and  201  along the rail  111 . 
         [0039]    Referring to  FIGS. 8   a  and  8   b , another embodiment of a driving mechanism  109   c  primarily includes a linkage structure  500 , a motor  501 , a lever  502 , and a magnetic element  514 . The linkage structure  500  includes a first rod  503  and a second rod  504  pivotally connected to each other. The first rod  503  has a first end  505  and a second end  506 , and the second rod  504  has a third end  507  and a fourth end  508 . 
         [0040]    As shown in  FIGS. 8   a  and  8   b , the main body  118  of the carrier  105  has a longitudinal projecting support portion  515 , and the first end  505  is pivotally connected thereto. Furthermore, the second lens  108  has a magnetic connection portion  516  pivotally connected to the fourth end  508 , as shown in  FIGS. 9   a  and  9   b . In this embodiment, the magnetic element  514  is fixed to the main body  118 , magnetically attracting the magnetic connection portion  516 . 
         [0041]    Referring to  FIG. 8   c , the second end  506  has a first joining portion  511 , such as a slot, and the third end  507  has a second joining portion  512 , such as a tab rotatably received in the slot. When the second lens  108  moves to the second position, as shown in  FIGS. 8   b  and  9   b , a spring  513  around the support portion  515  continuously pushes against the first end  505 , to retain the second lens  108  in the second position  201 . 
         [0042]    When the linkage structure  500  is in a first state, as shown in  FIG. 8   a , the linkage structure  500  forms a V-shaped structure, such that the second lens  108  is in the first position  200 . When the linkage structure  500  moves from the first state to a second state, as shown in  FIG. 8   b , the linkage structure  500  is unfolded and impels the second lens  108  to the second position  201 , such that the first and second rods  503  and  504  have an angle approximately 170°. Here, the motor  501  is disposed in the main body  118  of the carrier  105  and connected to the lever  502  for switching the linkage structure  500  between the first state ( FIG. 9   a ) and second states ( FIG. 9   b ). 
         [0043]    Referring to  FIG. 9   a , when the linkage structure  500  is in the first state, the second lens  108  is held in the first position  200  by magnetic attraction between the magnetic connection portion  516  and the magnetic element  514 . When switching the linkage structure  500  from the first state to the second state, the motor  501  impels the lever  502  along the direction  603 , as shown in  FIG. 9   a . Subsequently, the lever  502  pushes against the joint between the second and third ends  506  and  507 , such that the linkage structure  500  is unfolded to the second state. 
         [0044]    When the linkage structure  500  moves to the second state, as shown in  FIG. 9   b , the spring  513  continuously exerts a spring force on the first end  505  to retain the second lens  108  in the second position  201 . Furthermore, when the linkage structure  500  moves to the second state, the first joining portion  511  is joined with the second joining portion  512 , as shown in  FIG. 9   c , enhancing stability and positioning accuracy of the second lens  108 . In this embodiment, the first and second rods  503  and  504  form an angle approximately 170° when the linkage structure  500  is in the second state. 
         [0045]    When returning the linkage structure  500  from the second state to the first state, the motor  501  impels the lever  502  along the direction  604 , as shown in  FIG. 9   b . Subsequently, the lever  502  pull the joint between the second and third ends  506  and  507 , such that the linkage structure  500  returns to the first state as shown in  FIG. 9   a . Since the linkage structure  500  is movable between the first and second states by the driving mechanism  109   c , the second lens  108  can be alternatively switched between the first and second positions  200  and  201  for scanning regular or small objects. 
         [0046]    The invention provides a scan module including a first lens and a movable second lens for scanning regular or small objects. Different driving mechanisms for moving the second lens are disclosed according to the embodiments. When scanning a regular object, the primary lens is applied. When scanning a small object, the second lens is optically incorporated with the first lens, facilitating efficient pixel utilization and high resolution. 
         [0047]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.