Abstract:
A six-piece optical lens system comprises, in order from the object side to the image side: a first lens element with a positive refractive power having a convex object-side surface; a second lens element with a negative refractive power having a concave image-side surface; a third lens element with a negative refractive power; a fourth lens element with a positive refractive power having a concave object-side surface; a fifth lens element with a positive refractive power having a convex image-side surface; a sixth lens element with a negative refractive power having a concave image-side surface, each of the first, second, third, fourth, fifth and sixth lens elements has at least one aspheric surface. Thereby, such a system not only can be applied to a high resolution mobile phone, but also has a wide field of view, big stop, high pixel, high resolution and low height.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an optical lens system, and more particularly to a six-piece optical lens system. 
         [0003]    2. Description of the Prior Art 
         [0004]    In recent years, with the popularity of the mobile phone cameras, the optical lens system has become smaller in size, and the electronic sensor of a general digital camera is typically a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor. Due to advances in semiconductor manufacturing, the pixel size of sensor has been reduced continuously, and miniaturized optical lens systems have increasingly higher resolution. Therefore, there&#39;s an increasing demand for an imaging lens system with better image quality. 
         [0005]    Conventional miniaturized lens systems used in portable electronic products mostly consist of four lens elements, however, the resolution of the mobile phone camera has been improved rapidly. As the pixel size of electronic imaging sensors gradually becomes smaller and smaller, the system requires higher image quality, and miniaturization and high performance have become the trend of modern electronic products. The conventional optical lens system comprising four lens elements cannot satisfy the requirements of higher resolution optical lens systems. 
         [0006]    The present invention mitigates and/or obviates the aforementioned disadvantages. 
       SUMMARY OF THE INVENTION 
       [0007]    The primary objective of the present invention is to provide a six-piece optical lens system without having an excessively long total track length, the six-piece optical lens system not only can be applied to a high resolution mobile phone, but also has a wide field of view, big stop, high pixel, high resolution and low height. 
         [0008]    A six-piece optical lens system in accordance with the present invention comprises, in order from the object side to the image side: a first lens element with a positive refractive power having a convex object-side surface, at least one of the object-side and an image-side surfaces of the first lens element being aspheric; a second lens element with a negative refractive power having a concave image-side surface, at least one of an object-side and the image-side surfaces of the second lens element being aspheric; a third lens element with a negative refractive power, at least one of an object-side and an image-side surfaces of the third lens element being aspheric; a fourth lens element with a positive refractive power having a concave object-side surface, at least one of the object-side and an image-side surfaces of the fourth lens element being aspheric; a fifth lens element with a positive refractive power having a convex image-side surface, at least one of an object-side and the image-side surfaces of the fifth lens element being aspheric; and a sixth lens element with a negative refractive power having a concave image-side surface, at least one of an object-side and the image-side surfaces of the sixth lens element being aspheric. 
         [0009]    The present six-piece optical lens system further comprises a stop which is located between the first lens element and the second lens element. 
         [0010]    The present six-piece optical lens system further comprises a stop which is located in front of the object-side surface of the first lens element. 
         [0011]    According to one aspect of the present six-piece optical lens system, the focal length of the first lens element is f1, the focal length of the second lens element is f2, and they satisfy the relation: 0.25&lt;|f1|/|f2|&lt;0.75. If |f1|/|f2| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f1|/|f2| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0012]    According to another aspect of the present six-piece optical lens system, the focal length of the second lens element is f2, the focal length of the third lens element is f3, and they satisfy the relation: |f2|/|f3|&lt;0.25. If |f2|/|f3| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f2|/|f3| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0013]    According to another aspect of the present six-piece optical lens system, the focal length of the fifth lens element is f5, the focal length of the sixth lens element is f6, and they satisfy the relation: 0.7&lt;|f5|/|f6|&lt;3.6. If |f5|/|f6| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f5|/|f6| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0014]    According to another aspect of the present six-piece optical lens system, the focal length of the first lens element, the second lens element and the third lens element combined is f123, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 0.9&lt;|f123|/|f|&lt;1.5. If |f123|/|f| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f123|/|f| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0015]    According to another aspect of the present six-piece optical lens system, the focal length of the fourth lens element, the fifth lens element and the sixth lens element combined is f456, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 3&lt;|f456|/|f|&lt;7.5. If |f456|/|f| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f456|/|f| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0016]    According to another aspect of the present six-piece optical lens system, the focal length of the first lens element is f1, the focal length of the second lens element and the third lens element combined is f23, and they satisfy the relation: 0.4&lt;|f1|/|f23|&lt;0.7. If |f1|/|f23| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f1|/|f23| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0017]    According to another aspect of the present six-piece optical lens system, the focal length of the third lens element and the fourth lens element combined is f34, the focal length of the fifth lens element and the sixth lens element combined is f56, and they satisfy the relation: 0.3&lt;|f34|/|f56|&lt;1.9. If |f34|/|f56| satisfies the above relation, a wide field of view, big stop, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, If |f34|/|f56| exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low. 
         [0018]    According to another aspect of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, the distance from the object-side surface of the first lens element to the image plane along the optical axis is TL, and they satisfy the relation: 0.65&lt;|f/TL|&lt;1. If |f/TL| satisfies the above relation, the total track length of the optical lens system can be relatively short, and the requirement of miniaturization can be satisfied. 
         [0019]    According to another aspect of the present six-piece optical lens system, the first lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the first lens element are aspheric. The second lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the second lens element are aspheric. The third lens element is made of plastic and has a concave object-side surface and a convex image-side surface, and the object-side surface and the image-side surface of the third lens element are aspheric. The fourth lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the fourth lens element are aspheric. The fifth lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the fifth lens element are aspheric. The sixth lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the sixth lens element are aspheric. 
         [0020]    According to another aspect of the present six-piece optical lens system, the first lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the first lens element are aspheric. The second lens element is made of plastic and has a convex object-side surface, and the object-side surface and the image-side surface of the second lens element are aspheric. The third lens element is made of plastic and has a convex object-side surface and a concave image-side surface, and the object-side surface and the image-side surface of the third lens element are aspheric. The fourth lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the fourth lens element are aspheric. The fifth lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the fifth lens element are aspheric. The sixth lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the sixth lens element are aspheric. 
         [0021]    According to another aspect of the present six-piece optical lens system, the first lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the first lens element are aspheric. The second lens element is made of plastic and has a convex object-side surface, and the object-side surface and the image-side surface of the second lens element are aspheric. The third lens element is made of plastic and has a concave object-side surface and a convex image-side surface, and the object-side surface and the image-side surface of the third lens element are aspheric. The fourth lens element is made of plastic and has a convex image-side surface, and the object-side surface and the image-side surface of the fourth lens element are aspheric. The fifth lens element is made of plastic and has a concave object-side surface, and the object-side surface and the image-side surface of the fifth lens element are aspheric. The sixth lens element is made of plastic and has a convex object-side surface, and the object-side surface and the image-side surface of the sixth lens element are aspheric. 
         [0022]    The present invention will be presented in further details from the following descriptions with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1A  shows an optical lens system in accordance with a first embodiment of the present invention; 
           [0024]      FIG. 1B  shows the longitudinal spherical aberration curve, the astigmatic field curve, and the distortion curve of the first embodiment of the present invention; 
           [0025]      FIG. 2A  shows an optical lens system in accordance with a second embodiment of the present invention; 
           [0026]      FIG. 2B  shows the longitudinal spherical aberration curve, the astigmatic field curve, and the distortion curve of the second embodiment of the present invention; 
           [0027]      FIG. 3A  shows an optical lens system in accordance with a third embodiment of the present invention; 
           [0028]      FIG. 3B  shows the longitudinal spherical aberration curve, the astigmatic field curve, and the distortion curve of the third embodiment of the present invention; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Referring to  FIG. 1A , which shows a six-piece optical lens system in accordance with a first embodiment of the present invention, and  FIG. 1B  shows the longitudinal spherical aberration curves, the astigmatic field curves, and the distortion curve of the first embodiment of the present invention. A six-piece optical lens system in accordance with the first embodiment of the present invention comprises, in order from the object side to the image side: 
         [0030]    A first lens element  110  with a positive refractive power made of plastic has a convex object-side surface  111  and a convex image-side surface  112 , and the object-side surface  111  and the image-side surface  112  of the first lens element  110  are aspheric. 
         [0031]    A stop  100 . 
         [0032]    A second lens element  120  with a negative refractive power made of plastic has a concave object-side surface  121  and a convex image-side surface  122 , and the object-side surface  121  and the image-side surface  122  of the second lens element  120  are aspheric. 
         [0033]    A third lens element  130  with a negative refractive power made of plastic has a concave object-side surface  131  and a convex image-side surface  132 , and the object-side surface  131  and the image-side surface  132  of the third lens element  130  are aspheric. 
         [0034]    A fourth lens element  140  with a positive refractive power made of plastic has a concave object-side surface  141  and a convex image-side surface  142 , and the object-side surface  141  and the image-side surface  142  of the fourth lens element  140  are aspheric. 
         [0035]    A fifth lens element  150  with a positive refractive power made of plastic has a concave object-side surface  151  and a convex image-side surface  152 , and the object-side surface  151  and the image-side surface  152  of the fifth lens element  150  are aspheric. 
         [0036]    A sixth lens element  160  with a negative refractive power made of plastic has a concave object-side surface  161  and a concave image-side surface  162 , and the object-side surface  161  and the image-side surface  162  of the sixth lens element  160  are aspheric. 
         [0037]    An IR cut filter  170  made of glass is located between the image-side surface  162  of the sixth lens element  160  and an image plane  180  and has no influence on the focal length of the six-piece optical lens system. 
         [0038]    The equation for the aspheric surface profiles of the first embodiment is expressed as follows: 
         [0000]    
       
         
           
             z 
             = 
             
               
                 
                   ch 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       [ 
                       
                         1 
                         - 
                         
                           
                             ( 
                             
                               k 
                               + 
                               1 
                             
                             ) 
                           
                            
                           
                             c 
                             2 
                           
                            
                           
                             h 
                             2 
                           
                         
                       
                       ] 
                     
                     0.5 
                   
                 
               
               + 
               
                 A 
                  
                 
                     
                 
                  
                 
                   h 
                   4 
                 
               
               + 
               
                 Bh 
                 6 
               
               + 
               
                 Ch 
                 8 
               
               + 
               
                 Dh 
                 10 
               
               + 
               
                 Eh 
                 12 
               
               + 
               
                 Gh 
                 14 
               
               + 
               … 
             
           
         
       
     
         [0039]    wherein: 
         [0040]    z represents the value of a reference position with respect to a vertex of the surface of a lens and a position with a height h along the optical axis  190 ; 
         [0041]    k represents the conic constant; 
         [0042]    c represents the reciprocal of the radius of curvature; 
         [0043]    A, B, C, D, E, G, . . . : represent the high-order aspheric coefficients. 
         [0044]    In the first embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, and it satisfies the relation: 
         [0000]        f= 4.27. 
         [0045]    In the first embodiment of the present six-piece optical lens system, the f-number of the six-piece optical lens system is Fno, and it satisfies the relation: 
         [0000]      Fno=2.6. 
         [0046]    In the first embodiment of the present six-piece optical lens system, the field of view of the six-piece optical lens system is 2ω, and it satisfies the relation: 
         [0000]      2ω=70°.
 
         [0047]    In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element  110  is f1, the focal length of the second lens element  120  is f2, and they satisfy the relation: 
         [0000]      | f 1 |/|f 2|=0.478. 
         [0048]    In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element  120  is f2, the focal length of the third lens element  130  is f3, and they satisfy the relation: 
         [0000]      | f 2 |/|f 3|=0.1665. 
         [0049]    In the first embodiment of the present six-piece optical lens system, the focal length of the fifth lens element  150  is f5, the focal length of the sixth lens element  160  is f6, and they satisfy the relation: 
         [0000]      | f 5 |/|f 6|=1.219. 
         [0050]    In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element  110 , the second lens element  120  and the third lens element  130  combined is f123, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 123 |/|f|= 1.0523. 
         [0051]    In the first embodiment of the present six-piece optical lens system, the focal length of the fourth lens element  140 , the fifth lens element  150  and the sixth lens element  160  combined is f456, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 456 |/|f|= 6.411. 
         [0052]    In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element  110  is f1, the focal length of the second lens element  120  and the third lens element  130  combined is f23, and they satisfy the relation: 
         [0000]      | f 1 |/|f 23|=0.554. 
         [0053]    In the first embodiment of the present six-piece optical lens system, the focal length of the third lens element  130  and the fourth lens element  140  combined is f34, the focal length of the fifth lens element  150  and the sixth lens element  160  combined is f56, and they satisfy the relation: 
         [0000]      | f 34 |/|f 56|=1.7505. 
         [0054]    In the first embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, the distance from the object-side surface  111  of the first lens element  110  to the image plane  180  along the optical axis  190  is TL, and they satisfy the relation: 
         [0000]      | f/TL|= 0.8827. 
         [0055]    The detailed optical data of the first embodiment is shown in table 1, and the aspheric surface data is shown in table 2, wherein the units of the radius of curvature, the thickness and the focal length are expressed in mm. In the tables 1 and 2, the surfaces 1 and 2 represent the object-side surface  111  and the image-side surface  112  of the first lens element  110 , respectively, the surfaces 4 and 5 represent the object-side surface  121  and the image-side surface  122  of the second lens element  120 , respectively, the surfaces 6 and 7 represent the object-side surface  131  and the image-side surface  132  of the third lens element  130 , respectively, the surfaces 8 and 9 represent the object-side surface  141  and the image-side surface  142  of the fourth lens element  140 , respectively, the surfaces 10 and 11 represent the object-side surface  151  and the image-side surface  152  of the fifth lens element  150 , respectively, and the surfaces 12 and 13 represent the object-side surface  161  and the image-side surface  162  of the sixth lens element  160 , respectively. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 (Embodiment 1) 
               
               
                 f(focal length) = 4.27 mm, Fno = 2.6, 2ω = 70°. 
               
             
          
           
               
                 Surface 
                   
                 Curvature Radius 
                 Thickness 
                 Material 
                 nd 
                 vd 
               
               
                   
               
             
          
           
               
                 0 
                 Object 
                 Infinity 
                 Infinity 
                   
                   
                   
               
               
                 1 
                 Lens 1 
                 1.435174(ASP) 
                 0.559385 
                 Plastic 
                 1.544 
                 56 
               
               
                 2 
                   
                 −35.3053(ASP) 
                 −0.02018 
               
               
                 3 
                 Stop 
                 Infinity 
                 0.086894 
               
               
                 4 
                 Lens 2 
                 −16.5411(ASP) 
                 0.335885 
                 Plastic 
                 1.632 
                 23.9 
               
               
                 5 
                   
                 4.312157(ASP) 
                 0.515215 
               
               
                 6 
                 Lens 3 
                 −3.23406(ASP) 
                 0.252965 
                 Plastic 
                 1.634 
                 23.9 
               
               
                 7 
                   
                 −3.95999(ASP) 
                 0.234474 
               
               
                 8 
                 Lens 4 
                 −3.07836(ASP) 
                 0.271091 
                 Plastic 
                 1.535 
                 56 
               
               
                 9 
                   
                 −3.06743(ASP) 
                 0.044632 
               
               
                 10 
                 Lens 5 
                 −3.04683(ASP) 
                 0.619864 
                 Plastic 
                 1.535 
                 56 
               
               
                 11 
                   
                 −0.87029(ASP) 
                 0.26439 
               
               
                 12 
                 Lens 6 
                 −1.99264(ASP) 
                 0.394581 
                 Plastic 
                 1.535 
                 56 
               
               
                 13 
                   
                 1.739494(ASP) 
                 0.25 
               
               
                 14 
                 IR-filter 
                 Infinity 
                 0.21 
                 Glass 
                 1.5168 
                 64.167336 
               
               
                 15 
                   
                 Infinity 
                 0.820622 
               
               
                 16 
                 Image 
                 Infinity 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Surface # 
                 1 
                 2 
                 4 
                 5 
                 6 
                 7 
               
               
                   
               
               
                 K = 
                 −5.01966 
                 −626.924 
                 −108.1934 
                 21.05222 
                 −2.69857 
                 1.649066 
               
               
                 A = 
                 0.214555 
                 −0.04947 
                 0.010117 
                 0.038714 
                 −0.18397 
                 −0.10892 
               
               
                 B = 
                 −0.20072 
                 0.070579 
                 0.036831 
                 0.037631 
                 −0.12622 
                 −0.09402 
               
               
                 C = 
                 0.236388 
                 −0.26547 
                 0.251311 
                 0.115499 
                 0.353786 
                 0.145546 
               
               
                 D = 
                 −0.22271 
                 0.369915 
                 −0.91576 
                 −0.27497 
                 −0.43702 
                 −0.04676 
               
               
                 E = 
                 0.041779 
                 −0.29165 
                 1.428219 
                 0.45062 
                 0.325182 
                 0.024276 
               
               
                 F = 
                 −0.01734 
                 0.080338 
                 −0.74068 
                 −0.16004 
                 5.49E−04 
                 −0.00167 
               
               
                   
               
               
                 Surface # 
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 K = 
                 2.502976 
                 2.558725 
                 2.643467 
                 −3.46684 
                 −19.62368 
                 −14.27324 
               
               
                 A = 
                 0.009445 
                 0.009372 
                 0.00855 
                 −0.06355 
                 −0.0187 
                 −0.0584 
               
               
                 B = 
                 0.039076 
                 0.038861 
                 0.038114 
                 0.095408 
                 −0.02853 
                 0.016767 
               
               
                 C = 
                 −0.22488 
                 −0.22509 
                 −0.22539 
                 −0.11625 
                 0.012291 
                 −0.00591 
               
               
                 D = 
                 0.302791 
                 0.3021 
                 0.301972 
                 0.067785 
                 −7.55E−04 
                 0.001443 
               
               
                 E = 
                 −0.17078 
                 −0.171 
                 −0.17111 
                 −0.01712 
                 −2.09E−04 
                 −2.20E−04 
               
               
                 F = 
                 0.036297 
                 0.036365 
                 0.036243 
                 0.001525 
                  2.24E−05 
                  1.49E−05 
               
               
                   
               
             
          
         
       
     
         [0056]    Referring to  FIG. 2A , which shows a six-piece optical lens system in accordance with a second embodiment of the present invention, and  FIG. 2B  shows the longitudinal spherical aberration curves, the astigmatic field curves, and the distortion curve of the second embodiment of the present invention. A six-piece optical lens system in accordance with the second embodiment of the present invention comprises, in order from the object side to the image side: 
         [0057]    A stop  200 . 
         [0058]    A first lens element  210  with a positive refractive power made of plastic has a convex object-side surface  211  and a convex image-side surface  212 , and the object-side surface  211  and the image-side surface  212  of the first lens element  210  are aspheric. 
         [0059]    A second lens element  220  with a negative refractive power made of plastic has a convex object-side surface  221  and a concave image-side surface  222 , and the object-side surface  221  and the image-side surface  222  of the second lens element  220  are aspheric. 
         [0060]    A third lens element  230  with a negative refractive power made of plastic has a convex object-side surface  231  and a concave image-side surface  232 , and the object-side surface  231  and the image-side surface  232  of the third lens element  230  are aspheric. 
         [0061]    A fourth lens element  240  with a positive refractive power made of plastic has a concave object-side surface  241  and a convex image-side surface  242 , and the object-side surface  241  and the image-side surface  242  of the fourth lens element  240  are aspheric. 
         [0062]    A fifth lens element  250  with a positive refractive power made of plastic has a concave object-side surface  251  and a convex image-side surface  252 , and the object-side surface  251  and the image-side surface  252  of the fifth lens element  250  are aspheric. 
         [0063]    A sixth lens element  260  with a negative refractive power made of plastic has a concave object-side surface  261  and a concave image-side surface  262 , and the object-side surface  261  and the image-side surface  262  of the sixth lens element  260  are aspheric. 
         [0064]    An IR cut filter  270  made of glass is located between the image-side surface  262  of the fifth lens element  260  and an image plane  280  and has no influence on the focal length of the six-piece optical lens system. 
         [0065]    The equation for the aspheric surface profiles of the second embodiment is expressed as follows: 
         [0000]    
       
         
           
             z 
             = 
             
               
                 
                   ch 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       [ 
                       
                         1 
                         - 
                         
                           
                             ( 
                             
                               k 
                               + 
                               1 
                             
                             ) 
                           
                            
                           
                             c 
                             2 
                           
                            
                           
                             h 
                             2 
                           
                         
                       
                       ] 
                     
                     0.5 
                   
                 
               
               + 
               
                 A 
                  
                 
                     
                 
                  
                 
                   h 
                   4 
                 
               
               + 
               
                 Bh 
                 6 
               
               + 
               
                 Ch 
                 8 
               
               + 
               
                 Dh 
                 10 
               
               + 
               
                 Eh 
                 12 
               
               + 
               
                 Gh 
                 14 
               
               + 
               … 
             
           
         
       
     
         [0066]    wherein: 
         [0067]    z represents the value of a reference position with respect to a vertex of the surface of a lens and a position with a height h along the optical axis  290 ; 
         [0068]    k represents the conic constant; 
         [0069]    c represents the reciprocal of the radius of curvature; 
         [0070]    A, B, C, D, E, G, . . . : represent the high-order aspheric coefficients. 
         [0071]    In the second embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, and it satisfies the relation: 
         [0000]        f= 3.90. 
         [0072]    In the second embodiment of the present six-piece optical lens system, the f-number of the six-piece optical lens system is Fno, and it satisfies the relation: 
         [0000]      Fno=2.4. 
         [0073]    In the second embodiment of the present six-piece optical lens system, the field of view of the six-piece optical lens system is 2ω, and it satisfies the relation: 
         [0000]      2ω=74°.
 
         [0074]    In the second embodiment of the present six-piece optical lens system, the focal length of the first lens element  210  is f1, the focal length of the second lens element  220  is f2, and they satisfy the relation: 
         [0000]      | f 1 |/|f 2|=0.53. 
         [0075]    In the second embodiment of the present six-piece optical lens system, the focal length of the second lens element  220  is f2, the focal length of the third lens element  230  is f3, and they satisfy the relation: 
         [0000]      | f 2 |/|f 3|=0.0057. 
         [0076]    In the second embodiment of the present six-piece optical lens system, the focal length of the fifth lens element  250  is f5, the focal length of the sixth lens element  260  is f6, and they satisfy the relation: 
         [0000]      | f 5 |/|f 6|=3.336. 
         [0077]    In the second embodiment of the present six-piece optical lens system, the focal length of the first lens element  210 , the second lens element  220  and the third lens element  230  combined is f123, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 123 |/|f|= 1.2058. 
         [0078]    In the second embodiment of the present six-piece optical lens system, the focal length of the fourth lens element  240 , the fifth lens element  250  and the sixth lens element  260  combined is f456, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 456 |/|f|= 4.0536. 
         [0079]    In the second embodiment of the present six-piece optical lens system, the focal length of the first lens element  210  is f1, the focal length of the second lens element  220  and the third lens element  230  combined is f23, and they satisfy the relation: 
         [0000]      | f 1 |/|f 23|=0.54. 
         [0080]    In the second embodiment of the present six-piece optical lens system, the focal length of the third lens element  230  and the fourth lens element  240  combined is f34, the focal length of the fifth lens element  250  and the sixth lens element  260  combined is f56, and they satisfy the relation: 
         [0000]      | f 34 |/|f 56|=0.926. 
         [0081]    In the second embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, the distance from the object-side surface  211  of the first lens element  210  to the image plane  280  along the optical axis  290  is TL, and they satisfy the relation: 
         [0000]      | f/TL|= 0.795. 
         [0082]    The detailed optical data of the second embodiment is shown in table 3, and the aspheric surface data is shown in table 4, wherein the units of the radius of curvature, the thickness and the focal length are expressed in mm. In the tables 3 and 4, the surfaces 2 and 3 represent the object-side surface  211  and the image-side surface  212  of the first lens element  210 , respectively, the surfaces 4 and 5 represent the object-side surface  221  and the image-side surface  222  of the second lens element  220 , respectively, the surfaces 6 and 7 represent the object-side surface  231  and the image-side surface  232  of the third lens element  230 , respectively, the surfaces 8 and 9 represent the object-side surface  241  and the image-side surface  242  of the fourth lens element  240 , respectively, the surfaces 10 and 11 represent the object-side surface  251  and the image-side surface  252  of the fifth lens element  250 , respectively, and the surfaces 12 and 13 represent the object-side surface  261  and the image-side surface  262  of the sixth lens element  260 , respectively. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 (Embodiment 2) 
               
               
                 f(focal length) = 3.90 mm, Fno = 2.4, 2ω = 74°. 
               
             
          
           
               
                 Surface 
                   
                 Curvature Radius 
                 Thickness 
                 Material 
                 nd 
                 vd 
               
               
                   
               
             
          
           
               
                 0 
                 Object 
                 Infinity 
                 Infinity 
                   
                   
                   
               
               
                 1 
                 Stop 
                 Infinity 
                 −0.15 
               
               
                 2 
                 Lens 1 
                 1.596546(ASP) 
                 0.529623 
                 Plastic 
                 1.544 
                 56 
               
               
                 3 
                   
                 −25.6747(ASP) 
                 0.066486 
               
               
                 4 
                 Lens 2 
                  7.86645(ASP) 
                 0.24 
                 Plastic 
                 1.634 
                 23.9 
               
               
                 5 
                   
                 2.318585(ASP) 
                 0.434229 
               
               
                 6 
                 Lens 3 
                  8.91721(ASP) 
                 0.253925 
                 Plastic 
                 1.634 
                 23.9 
               
               
                 7 
                   
                 8.686995(ASP) 
                 0.115219 
               
               
                 8 
                 Lens 4 
                 −2.21098(ASP) 
                 0.715868 
                 Plastic 
                 1.535 
                 56 
               
               
                 9 
                   
                 −0.87345(ASP) 
                 0.278673 
               
               
                 10 
                 Lens 5 
                 −0.71418(ASP) 
                 0.389269 
                 Plastic 
                 1.544 
                 56 
               
               
                 11 
                   
                 −0.71794(ASP) 
                 0.095827 
               
               
                 12 
                 Lens 6 
                  −26.082(ASP) 
                 0.347289 
                 Plastic 
                 1.535 
                 56 
               
               
                 13 
                   
                 1.186461(ASP) 
                 0.4 
               
               
                 14 
                 IR-filter 
                 Infinity 
                 0.21 
                 Glass 
                 1.5168 
                 64.167336 
               
               
                 15 
                   
                 Infinity 
                 0.826444 
               
               
                 16 
                 Image 
                 Infinity 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Surface # 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
               
               
                 K= 
                 −7.67883 
                 147.8918 
                 57.26706 
                 −7.48836 
                 −301.261 
                 −126.34 
               
               
                 A = 
                 0.212864 
                 −0.07265 
                 −0.12431 
                 0.011061 
                 −0.17358 
                 −0.08292 
               
               
                 B = 
                 −0.19149 
                 0.132786 
                 0.277298 
                 0.175179 
                 −0.13875 
                 −0.08706 
               
               
                 C = 
                 0.130194 
                 −0.25106 
                 −0.03195 
                 0.003449 
                 0.237548 
                 0.103217 
               
               
                 D = 
                 −0.12288 
                 0.236551 
                 −0.7191 
                 −0.19921 
                 −0.21948 
                 −0.03569 
               
               
                 E = 
                 0.072709 
                 −0.42558 
                 0.83351 
                 0.107166 
                 0.16931 
                 0.016203 
               
               
                 F = 
                 −0.0795 
                 0.292749 
                 −0.23332 
                 0.054539 
                 −0.05625 
                 −0.00475 
               
               
                   
               
               
                 Surface # 
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 K = 
                 0.885623 
                 −3.09255 
                 −3.0399 
                 −3.07962 
                 −399.446 
                 −9.4764 
               
               
                 A = 
                 0.110279 
                 −0.09452 
                 −0.0998 
                 −0.1006 
                 −0.04068 
                 −0.06655 
               
               
                 B = 
                 0.033922 
                 0.09376 
                 0.096269 
                 0.091029 
                 −0.02153 
                 0.018397 
               
               
                 C = 
                 −0.21063 
                 −0.0951 
                 −0.0928 
                 −0.09492 
                 0.011269 
                 −0.00656 
               
               
                 D = 
                 0.303749 
                 0.065916 
                 0.066786 
                 0.066454 
                 −0.00088 
                 0.001536 
               
               
                 E = 
                 −0.17624 
                 −0.01915 
                 −0.01923 
                 −0.01908 
                 −1.66E−04 
                 −1.95E−04 
               
               
                 F = 
                 0.036326 
                 0.002097 
                 0.001678 
                 0.001859 
                  2.04E−05 
                  9.90E−06 
               
               
                   
               
             
          
         
       
     
         [0083]    Referring to  FIG. 3A , which shows a six-piece optical lens system in accordance with a second embodiment of the present invention, and  FIG. 3B  shows the longitudinal spherical aberration curves, the astigmatic field curves, and the distortion curve of the second embodiment of the present invention. A six-piece optical lens system in accordance with the third embodiment of the present invention comprises, in order from the object side to the image side: 
         [0084]    A stop  300 . 
         [0085]    A first lens element  310  with a positive refractive power made of plastic has a convex object-side surface  311  and a convex image-side surface  312 , and the object-side surface  311  and the image-side surface  312  of the first lens element  310  are aspheric. 
         [0086]    A second lens element  320  with a negative refractive power made of plastic has a convex object-side surface  321  and a concave image-side surface  322 , and the object-side surface  321  and the image-side surface  322  of the second lens element  320  are aspheric. 
         [0087]    A third lens element  330  with a negative refractive power made of plastic has a concave object-side surface  331  and a convex image-side surface  332 , and the object-side surface  331  and the image-side surface  332  of the third lens element  330  are aspheric. 
         [0088]    A fourth lens element  340  with a positive refractive power made of plastic has a concave object-side surface  341  and a convex image-side surface  342 , and the object-side surface  341  and the image-side surface  342  of the fourth lens element  340  are aspheric. 
         [0089]    A fifth lens element  350  with a positive refractive power made of plastic has a concave object-side surface  351  and a convex image-side surface  352 , and the object-side surface  351  and the image-side surface  352  of the fifth lens element  350  are aspheric. 
         [0090]    A sixth lens element  360  with a negative refractive power made of plastic has a convex object-side surface  361  and a concave image-side surface  362 , and the object-side surface  361  and the image-side surface  362  of the sixth lens element  360  are aspheric. 
         [0091]    An IR cut filter  370  made of glass is located between the image-side surface  362  of the fifth lens element  360  and an image plane  380  and has no influence on the focal length of the six-piece optical lens system. 
         [0092]    The equation for the aspheric surface profiles of the third embodiment is expressed as follows: 
         [0000]    
       
         
           
             z 
             = 
             
               
                 
                   ch 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       [ 
                       
                         1 
                         - 
                         
                           
                             ( 
                             
                               k 
                               + 
                               1 
                             
                             ) 
                           
                            
                           
                             c 
                             2 
                           
                            
                           
                             h 
                             2 
                           
                         
                       
                       ] 
                     
                     0.5 
                   
                 
               
               + 
               
                 A 
                  
                 
                     
                 
                  
                 
                   h 
                   4 
                 
               
               + 
               
                 Bh 
                 6 
               
               + 
               
                 Ch 
                 8 
               
               + 
               
                 Dh 
                 10 
               
               + 
               
                 Eh 
                 12 
               
               + 
               
                 Gh 
                 14 
               
               + 
               … 
             
           
         
       
     
         [0093]    wherein: 
         [0094]    z represents the value of a reference position with respect to a vertex of the surface of a lens and a position with a height h along the optical axis  390 ; 
         [0095]    k represents the conic constant; 
         [0096]    c represents the reciprocal of the radius of curvature; 
         [0097]    A, B, C, D, E, G, . . . : represent the high-order aspheric coefficients. 
         [0098]    In the third embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, and it satisfies the relation: 
         [0000]        f= 3.63. 
         [0099]    In the third embodiment of the present six-piece optical lens system, the f-number of the six-piece optical lens system is Fno, and it satisfies the relation: 
         [0000]      Fno=2.2. 
         [0100]    In the third embodiment of the present six-piece optical lens system, the field of view of the six-piece optical lens system is 2ω, and it satisfies the relation: 
         [0000]      2ω=77.5°.
 
         [0101]    In the third embodiment of the present six-piece optical lens system, the focal length of the first lens element  310  is f1, the focal length of the second lens element  320  is f2, and they satisfy the relation: 
         [0000]      | f 1 |/|f 2|=0.514. 
         [0102]    In the third embodiment of the present six-piece optical lens system, the focal length of the second lens element  320  is f2, the focal length of the third lens element  330  is f3, and they satisfy the relation: 
         [0000]      | f 2 |/|f 3|=0.004. 
         [0103]    In the third embodiment of the present six-piece optical lens system, the focal length of the fifth lens element  350  is f5, the focal length of the sixth lens element  360  is f6, and they satisfy the relation: 
         [0000]      | f 5 |/|f 6|=1.135. 
         [0104]    In the third embodiment of the present six-piece optical lens system, the focal length of the first lens element  310 , the second lens element  320  and the third lens element  330  combined is f123, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 123 |/|f|= 1.246. 
         [0105]    In the third embodiment of the present six-piece optical lens system, the focal length of the fourth lens element  340 , the fifth lens element  350  and the sixth lens element  360  combined is f456, the focal length of the six-piece optical lens system is f, and they satisfy the relation: 
         [0000]      | f 456 |/|f|= 5.0723. 
         [0106]    In the third embodiment of the present six-piece optical lens system, the focal length of the first lens element  310  is f1, the focal length of the second lens element  320  and the third lens element  330  combined is f23, and they satisfy the relation: 
         [0000]      | f 1 |/|f 23|=0.521. 
         [0107]    In the third embodiment of the present six-piece optical lens system, the focal length of the third lens element  330  and the fourth lens element  340  combined is f34, the focal length of the fifth lens element  350  and the sixth lens element  360  combined is f56, and they satisfy the relation: 
         [0000]      | f 34 |/|f 56|=0.459. 
         [0108]    In the third embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, the distance from the object-side surface  311  of the first lens element  310  to the image plane  380  along the optical axis  390  is TL, and they satisfy the relation: 
         [0000]      | f/TL|= 0.7735. 
         [0109]    The detailed optical data of the third embodiment is shown in table 5, and the aspheric surface data is shown in table 6, wherein the units of the radius of curvature, the thickness and the focal length are expressed in mm. In the tables 5 and 6, the surfaces 2 and 3 represent the object-side surface  311  and the image-side surface  312  of the first lens element  310 , respectively, the surfaces 4 and 5 represent the object-side surface  321  and the image-side surface  322  of the second lens element  320 , respectively, the surfaces 6 and 7 represent the object-side surface  331  and the image-side surface  332  of the third lens element  330 , respectively, the surfaces 8 and 9 represent the object-side surface  341  and the image-side surface  342  of the fourth lens element  340 , respectively, the surfaces 10 and 11 represent the object-side surface  351  and the image-side surface  352  of the fifth lens element  350 , respectively, and the surfaces 12 and 13 represent the object-side surface  361  and the image-side surface  362  of the sixth lens element  360 , respectively. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 (Embodiment 3) 
               
               
                 f(focal length) = 3.63 mm, Fno = 2.2, 2ω = 77.5°. 
               
             
          
           
               
                 Surface 
                   
                 Curvature Radius 
                 Thickness 
                 Material 
                 nd 
                 vd 
               
               
                   
               
             
          
           
               
                 0 
                 Object 
                 Infinity 
                 Infinity 
                   
                   
                   
               
               
                 1 
                 Stop 
                 Infinity 
                 −0.18 
               
               
                 2 
                 Lens 1 
                 1.607831(ASP) 
                 0.530137 
                 Plastic 
                 1.544 
                 56 
               
               
                 3 
                   
                 −16.9731(ASP) 
                 0.053051 
               
               
                 4 
                 Lens 2 
                 7.712296(ASP) 
                 0.24 
                 Plastic 
                 1.634 
                 23.9 
               
               
                 5 
                   
                 2.323604(ASP) 
                 0.426173 
               
               
                 6 
                 Lens 3 
                 10.45147(ASP) 
                 0.230942 
                 Plastic 
                 1.634 
                 23.9 
               
               
                 7 
                   
                 10.23401(ASP) 
                 0.108656 
               
               
                 8 
                 Lens 4 
                 −2.57973(ASP) 
                 0.351374 
                 Plastic 
                 1.535 
                 56 
               
               
                 9 
                   
                 −2.27911(ASP) 
                 0.07082 
               
               
                 10 
                 Lens 5 
                 −2.12324(ASP) 
                 0.619718 
                 Plastic 
                 1.535 
                 56 
               
               
                 11 
                   
                 −0.90514(ASP) 
                 0.293824 
               
               
                 12 
                 Lens 6 
                 70.42933(ASP) 
                 0.463915 
                 Plastic 
                 1.535 
                 56 
               
               
                 13 
                   
                 1.158274(ASP) 
                 0.4 
               
               
                 14 
                 IR-filter 
                 Infinity 
                 0.21 
                 Glass 
                 1.5168 
                 64.167336 
               
               
                 15 
                   
                 Infinity 
                 0.696045 
               
               
                 16 
                 Image 
                 Infinity 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Surface # 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
               
               
                 K = 
                 −8.03083 
                 −669.517 
                 49.69245 
                 −8.16321 
                 −638.227 
                 −247.265 
               
               
                 A = 
                 0.214434 
                 −0.07389 
                 −0.1241 
                 0.006053 
                 −0.17705 
                 −0.08306 
               
               
                 B = 
                 −0.18913 
                 0.125135 
                 0.28397 
                 0.164743 
                 −0.14222 
                 −0.08298 
               
               
                 C = 
                 0.122843 
                 −0.23767 
                 −0.02356 
                 0.006625 
                 0.239429 
                 0.106728 
               
               
                 D = 
                 −0.12835 
                 0.248922 
                 −0.70371 
                 −0.17519 
                 −0.21357 
                 −0.03712 
               
               
                 E = 
                 0.082263 
                 −0.42704 
                 0.849026 
                 0.135421 
                 0.175081 
                 0.015334 
               
               
                 F = 
                 −0.07367 
                 0.277228 
                 −0.26531 
                 0.011423 
                 −0.05398 
                 −0.00601 
               
               
                   
               
               
                 Surface # 
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 K = 
                 1.089672 
                 1.248064 
                 1.112785 
                 −3.27383 
                 579.9519 
                 −7.08033 
               
               
                 A = 
                 0.107258 
                 0.09862 
                 0.099693 
                 −0.10043 
                 −0.04034 
                 −0.06318 
               
               
                 B = 
                 0.030909 
                 0.02595 
                 0.031688 
                 0.091441 
                 −0.022 
                 0.018433 
               
               
                 C = 
                 −0.21311 
                 −0.21384 
                 −0.21271 
                 −0.0942 
                 0.011214 
                 −0.00665 
               
               
                 D = 
                 0.302891 
                 0.302751 
                 0.303735 
                 0.066904 
                 −8.74E−04 
                 0.001536 
               
               
                 E = 
                 −0.17614 
                 −0.1761 
                 −0.17564 
                 −0.019 
                 −0.00016 
                 −1.93E−04 
               
               
                 F = 
                 0.036669 
                 0.036541 
                 0.036266 
                 0.00176 
                  2.06E−05 
                  1.01E−05 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                 Embodiment 1 
                 Embodiment 2 
                 Embodiment 3 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 f 
                 4.27 
                 3.90 
                 3.63 
               
               
                 Fno 
                 2.6 
                 2.4 
                 2.2 
               
               
                 2ω 
                 70 
                 74 
                 77.5 
               
               
                 |f1|/|f2| 
                 0.478 
                 0.53 
                 0.514 
               
               
                 |f2|/|f3| 
                 0.1665 
                 0.0057 
                 0.004 
               
               
                 |f5|/|f6| 
                 1.219 
                 3.336 
                 1.135 
               
               
                 |f123|/|f| 
                 1.0523 
                 1.2058 
                 1.246 
               
               
                 |f456|/|f| 
                 6.411 
                 4.0536 
                 5.0723 
               
               
                 |f1|/|f23| 
                 0.554 
                 0.54 
                 0.521 
               
               
                 |f34|/|f56| 
                 1.7505 
                 0.926 
                 0.459 
               
               
                 |f/TL| 
                 0.8827 
                 0.795 
                 0.7735 
               
               
                   
               
             
          
         
       
     
         [0110]    It is to be noted that the tables 1-6 show different data from the different embodiments, however, the data of the different embodiments is obtained from experiments. Therefore, any product of the same structure is deemed to be within the scope of the present invention even if it uses different data. Table 7 lists the relevant data for the various embodiments of the present invention. 
         [0111]    In the present six-piece optical lens system, the lens elements can be made of glass or plastic. If the lens elements are made of glass, there is more freedom in distributing the refractive power of the six-piece optical lens system. If the lens elements are made of plastic, the cost will be effectively reduced. 
         [0112]    In the present six-piece optical lens system, if the object-side or the image-side surface of the lens elements is convex, the object-side or the image-side surface of the lens elements in proximity of the optical axis is convex. If the object-side or the image-side surface of the lens elements is concave, the object-side or the image-side surface of the lens elements in proximity of the optical axis is concave. 
         [0113]    While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.