Abstract:
An autofocus system is disclosed. The autofocus system includes a lens assembly, an upper actuator, and a lower actuator. The upper and the lower actuators have stationary elements and movable elements. The lens assembly is attached to the movable elements of the upper and the lower actuators. The autofocus system allows three degrees of freedoms of translational adjustments and two degrees of freedoms of rotational adjustments.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims benefit of a provisional patent application 62/096,854. The disclosure made in the provisional patent application 62/096,854 is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to an autofocus system for a camera module. More particularly, the present invention relates to an autofocus system allowing three degrees of freedoms of translational adjustments and two degrees of freedoms of rotational adjustments. 
       BACKGROUND OF THE INVENTION 
       [0003]    Autofocus is now a standard function in miniature cameras. There is a constant need to improve performance of autofocus. It is advantageous to extend the autofocus technology to include more degrees of freedoms of translational and rotational adjustments. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention discloses an autofocus system that allows three degrees of freedoms of translational adjustments and two degrees of freedoms of rotational adjustments. The autofocus system includes a lens assembly, an upper actuator, and a lower actuator. The upper and the lower actuators have stationary elements and movable elements. The lens assembly is attached to the movable elements of the upper and the lower actuators. In addition to improving the autofocus function, the capabilities of the translational adjustments and the rotational adjustments may balance the shock and vibration induced by user&#39;s hands. Thus, the steady-shot function of the camera module is also improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a schematic perspective view of an autofocus system in examples of the present disclosure. 
           [0006]      FIG. 2  is a bottom view of the autofocus system of  FIG. 1 . 
           [0007]      FIG. 3  is a cross-sectioned view of another autofocus system in examples of the present disclosure. 
           [0008]      FIG. 4  is a schematic perspective view of an actuator in examples of the present disclosure. 
           [0009]      FIG. 5  is an exploded plot of the actuator of  FIG. 4 . 
           [0010]      FIG. 6  is a top view of the actuator of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]      FIG. 1  is a schematic perspective view of an autofocus system  100  in examples of the present disclosure.  FIG. 2  is a bottom view of autofocus system  100  of  FIG. 1 . As shown in  FIG. 1  and  FIG. 2 , autofocus system  100  includes a lens assembly  120 , an upper actuator  1100  and a lower actuator  2100 . Upper actuator  1100  includes one or more upper stationary elements  1500 , a first upper translation element  1200  to translate along X direction, a second upper translation element  1300  to translate along Y direction, and a third upper translation element  1400  to translate along Z direction. Lower actuator  2100  includes one or more lower stationary elements  2500 , a first lower translation element  2200  to translate along X direction, a second lower translation element  2300  to translate along Y direction, and a third lower translation element  2400  to translate along Z direction. Lens assembly  120  may attach to first upper translation element  1200  and first lower translation element  2200 . 
         [0012]    In examples of the present disclosure, the translations of translation elements  1200 ,  1300 ,  1400 ,  2200 ,  2300 , and  2400  may be driven by electrostatic comb drives. 
         [0013]    In examples of the present disclosure, lens assembly  120  moves along positive X direction when first upper translation element  1200  and first lower translation element  2200  translate a positive displacement along X axis. Lens assembly  120 , first upper translation element  1200  and first lower translation element  2200  move along positive Y direction when second upper translation element  1300  and second lower translation element  2300  translate a positive displacement along Y axis. Lens assembly  120 , first upper translation element  1200 , first lower translation element  2200 , second upper translation element  1300  and second lower translation element  2300  move along positive Z direction when third upper translation element  1400  and third lower translation element  2400  translate a positive displacement along Z axis. 
         [0014]    In examples of the present disclosure, lens assembly  120  rotates about an axis parallel to Y axis when first upper translation element  1200  translates a positive displacement along X axis and first lower translation element  2200  translates a negative displacement along X axis. Lens assembly  120 , first upper translation element  1200  and first lower translation element  2200  rotates about an axis parallel to X axis when second upper translation element  1300  translates a negative displacement along Y axis and second lower translation element  2300  translates a positive displacement along Y axis. 
         [0015]    In one example, lens assembly  120  includes a single lens. In another example, lens assembly  120  includes a barrel and one or more lenses. 
         [0016]      FIG. 3  is a cross-sectioned view of another autofocus system  300  in examples of the present disclosure. Autofocus system  300  includes a lens assembly  320 , an upper actuator  3100 , a lower actuator  4100 , and a substrate  340 . Substrate  340  may be located between upper actuator  3100  and lower actuator  4100 . Substrate  340  may have an annular opening to receive lens assembly  320 . A first set of solder balls  360  may connect substrate  340  and upper actuator  3100 . A second set of solder balls  380  may connect substrate  340  and lower actuator  4100 . 
         [0017]      FIG. 4  is a schematic perspective view of an actuator  1100  in examples of the present disclosure. Actuator  1100  includes one or more stationary elements  1500 , a first translation element  1200  to translate along X direction, a second translation element  1300  to translate along Y direction, and a third translation element  1400  to translate along Z direction. 
         [0018]    In examples of the present disclosure, first translation element  1200 , second translation element  1300 , and third translation element  1400  are in cylindrical shapes and have the same central axis (Z axis). In one example, the radius of first translation element  1200  is smaller than the radius of second translation element  1300  and the radius of second translation element  1300  is smaller than the radius of third translation element  1400 . In another example, the radius of first translation element  1200  is larger than the radius of second translation element  1300  and the radius of third translation element  1400  is larger than the radius of first translation element  1200 . 
         [0019]      FIG. 5  is an exploded plot of actuator  1100  of  FIG. 4 . Actuator  1100  may include a top layer  1111  and a bottom layer  1191 . In one example, top layer  1111  is attached to bottom layer  1191 . In another example, top layer  1111  is attached to a middle layer (not shown) and the middle layer is attached to bottom layer  1191 . In examples of the present disclosure, top layer  1111  and bottom layer  1191  are made of silicon and middle layer is made of silicon oxide. 
         [0020]    Top layer  1111  may include ground electrode member  1122 , ground electrode member  1124 , ground electrode member  1126 , X-driving electrode member  1132 , X-driving electrode member  1134 , Y-driving electrode member  1142 , and Y-driving electrode member  1144 . Ground electrode members  1122 ,  1124 , and  1126  connect to ground. X-driving electrode members  1132  and  1134  connect to driving voltage potentials. Y-driving electrode members  1142  and  1144  connect to driving voltage potentials. 
         [0021]    Bottom layer  1191  may include Z-driving electrodes  1542 ,  1544 ,  1546 ,  1548 ,  1550 ,  1552 ,  1554 , and  1556 , support ring  1322 , and support ring  1422 . 
         [0022]    First translation element  1200  may be in top layer  1111 . Second translation element  1300  may include arc member  1312 , arc member  1314 , arc member  1316 , and arc member  1318  in top layer  1111  and support ring  1322  in bottom layer  1911 . Third translation element  1400  may include arc member  1412 , arc member  1414 , arc member  1416 , and arc member  1418  in top layer  1111  and support ring  1422  in bottom layer  1911 . 
         [0023]    In examples of the present disclosure, moving electrodes  1442 ,  1444 ,  1446 ,  1448 ,  1450 ,  1452 ,  1454 , and  1456  are engaged with Z-driving electrodes  1542 ,  1544 ,  1546 ,  1548 ,  1550 ,  1552 ,  1554 , and  1556  to form eight out-of-plane comb drives. 
         [0024]      FIG. 6  is a top view of actuator  1100  of  FIG. 4 . Actuator  1100  further includes X-translational springs  1282 ,  1284 ,  1286 , and  1288 , Y-translational springs  1392 ,  1394 ,  1396 , and  1398 , and one or more Z-translational springs  1591 . X-translational springs  1282 ,  1284 ,  1286 , and  1288  connect first translation element  1200  and second translation element  1300 . Y-translational springs  1392 ,  1394 ,  1396 , and  1398  connect second translation element  1300  and third translation element  1400 . 
         [0025]    Moving electrodes  1272  and  1274  extending from first itranslation element  1200  are engaged with X-driving electrodes  1372  and  1374  extendng from second translation element  1300  to form two in-plane comb drives. Moving electrodes  1362  and  1364  extending from second translation element  1300  are engaged with Y-driving electrodes  1462  and  1464  extending from third translation element  1400  to form two in-plane comb drives. 
         [0026]    Those of ordinary skill in the art may recognize that modifications of the embodiments disclosed herein are possible. For example, the numbers of springs may vary; the springs may be linear springs, serpentine springs, or other kinds of springs; the numbers of comb drives may vary; and the numbers and the shapes of the comb teeth of the comb drives may vary. Other modifications may occur to those of ordinary skill in this art, and all such modifications are deemed to fall within the purview of the present invention, as defined by the claims.