Abstract:
A zoom lens includes a first lens unit, a second lens unit, a third lens unit and a fourth lens unit. The third lens unit includes a movable barrel, a first slidable member able to move in a first direction perpendicular to the optical axis, and a second slidable member able to move along a second direction perpendicular to the optical axis and also perpendicular to the first direction. The movable barrel includes a first Hall member and a first coil, the first slidable member comprises a second Hall member and a second coil. A first magnet is aligned with the first coil, and a second magnet is aligned with the second coil, both coils can be independently energized to compensate any shaking movements experienced by the Hall members.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to zoom lenses and imaging devices, and particularly, relates to a zoom lens and an imaging device with image stabilizing function. 
         [0003]    2. Description of Related Art 
         [0004]    Many imaging devices, such as digital cameras, digital video cameras, and monitoring devices, have image stabilizing function for correcting image blur due to shaking of the imaging device during shooting. 
         [0005]    An imaging device with image stabilizing function will include a shake detecting unit for detecting any shaking of the imaging device, a calculating unit for calculating the degree of the shaking, and a blur correcting unit with a compensating lens for correcting image blur due to the shaking. However, the detecting unit, the calculating unit and the blur correcting unit each have a complicated structure and add to the overall complexity of the imaging device, and increase the overall size of the imaging device. 
         [0006]    Therefore, it is desirable to provide a zoom lens and an imaging device which can overcome the limitations described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The components of the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views. 
           [0008]      FIG. 1  is an exploded view of an imaging device in accordance with a first exemplary embodiment of the present disclosure, the imaging device including a fixed barrel, a gear barrel, an outer guiding barrel, a front guiding barrel, a cam barrel, an inner guiding barrel, a first lens unit and a third lens unit. 
           [0009]      FIG. 2  is an enlarged view of the fixed barrel of the imaging device of  FIG. 1 . 
           [0010]      FIG. 3  is an enlarged view of the gear barrel of the imaging device of  FIG. 1 . 
           [0011]      FIG. 4  is an enlarged view of the outer guiding barrel of the imaging device of  FIG. 1 . 
           [0012]      FIG. 5  is an enlarged view of the front guiding barrel of the imaging device of  FIG. 1 . 
           [0013]      FIG. 6  is an enlarged view of the cam barrel of the imaging device of FIG.  1 . 
           [0014]      FIG. 7  is an enlarged view of the inner guiding barrel of the imaging device of  FIG. 1 . 
           [0015]      FIG. 8  is an enlarged view of the first lens unit of the imaging device of  FIG. 1 . 
           [0016]      FIG. 9  is an exploded view of the third lens unit of the imaging device of  FIG. 1 , the third lens unit including a first magnet. 
           [0017]      FIG. 10  is similar to  FIG. 9  but viewing the third lens from another angle. 
           [0018]      FIG. 11  is a schematic view of the first magnet of  FIG. 9 . 
           [0019]      FIG. 12  is an assembled and isometric view of the imaging device of  FIG. 1 . 
           [0020]      FIG. 13  is a sectional view along line VI-VI of the imaging device of  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Embodiments of the disclosure will be described with reference to the accompanying drawings. 
         [0022]    Referring to  FIG. 1  and  FIG. 5 , an imaging device  100 , according to a first exemplary embodiment, includes a zoom lens  10  for capturing images of objects, an image sensing module  20  for sensing the images captures by the zoom lens  10 , a first driving unit  30  and a second driving unit  40 . 
         [0023]    The zoom lens  10  includes, from an object side to an image side, a lens barrel unit  11 , a first lens unit  12 , a second lens unit  13 , a third lens unit  14  and a fourth lens unit  15 . The first lens unit  12 , the second lens unit  13 , the third lens unit  14  and the fourth lens unit  15  are aligned with each other from the object side to the image side along one optical axis. 
         [0024]    The lens barrel unit  11  includes a fixed barrel  111 , a gear barrel  112 , an outer guiding barrel  113 , a front guiding barrel  114 , a cam barrel  115  and an inner guiding barrel  116 . 
         [0025]    Referring also to  FIG. 2 , the fixed barrel  111  defines a number of first straight guiding grooves  111   a  and a number of first inclined guiding grooves  111   b.  The straight guiding grooves  111   a  extend along a direction that is substantially parallel to the optical axis, and the first inclined guiding grooves  111   b  represent straight lines which have been imposed on a cylinder standing vertically, where each line is slanted at a single predetermined angle from the vertical (in the following description, the words “straight” and “inclined” respectively have the same meaning as used here). The fixed barrel  111  further defines an entrance  111   c  in the side surface thereof for allowing the first driving unit  30  to enter into the fixed barrel  111 . 
         [0026]    The outer diameter of the gear barrel  112  is less than the inner diameter of the fixed barrel  111 . Referring also to  FIG. 3 , the gear barrel  112  includes a number of first protrusions  112   a  and a teeth portion  112   b.  The first protrusions  112   a  are formed on an outer surface of the gear barrel  112  nearby an object side end of the gear barrel  112 . The teeth portion  112   b  is formed on the outer surface of the gear barrel  112  and extends a distance along a circumferential direction of the gear barrel  112 . In this embodiment, the length of the teeth portion  112   b  is substantially one third of the outer perimeter of the gear barrel  112 . The gear barrel  112  defines a number of second straight guiding grooves  112   c  in the inner surface thereof. The gear barrel  112  includes a number of first engaging blocks  112   d  formed on the inner surface thereof. In this embodiment, each first engaging block  112   d  corresponds to a second straight guiding groove  112   c,  and each first engaging block  112   d  is positioned at an end of a corresponding second straight guiding groove  112   c  towards the object side. 
         [0027]    The outer diameter of the outer guiding barrel  113  is less than the inner diameter of the gear barrel  112 . Referring also to  FIG. 4 , the outer guiding barrel  113  defines a number of through second inclined guiding grooves  113   a  each corresponding to a second straight guiding groove  112   c.  The outer guiding barrel  113  includes a first stop plate  113   b  formed on an end thereof towards the image side. The first stop plate  113   b  includes a number of second protrusions  113   c  formed on a peripheral edge thereof corresponding to the first straight guiding grooves  111   a.  The outer guiding barrel  113  defines a first engaging groove  113   d  in the outer surface thereof corresponding to the first engaging blocks  112   d.  The engaging groove  113   d  is positioned at an end of the outer guiding barrel  113  towards the object side. The outer guiding barrel  113  further defines a number of third straight guiding grooves  113   e  and a number of fourth straight guiding grooves  113   f  in an inner surface thereof. 
         [0028]    The outer diameter of the front guiding barrel  114  is less than the inner diameter of the outer guiding barrel  113 . Referring also to  FIG. 5 , the front guiding barrel  114  includes a number of guiding blocks  114   a  formed on an outer surface thereof, and the guiding blocks  114   a  are near an end of the front guiding barrel  114  towards the image side. The front guiding barrel  114  defines a number of fifth straight guiding grooves  114   b  and a number of second engaging grooves  114   c  in an inner surface thereof. The second engaging grooves  114   c  are at an end of the front guiding barrel  114  towards the image side. 
         [0029]    The outer diameter of the cam barrel  115  is less than the inner diameter of the front guiding barrel  114 . Referring also to  FIG. 6 , the cam barrel  115  includes a number of third protrusions  115   a  formed on an outer surface thereof each corresponding to a second inclined guiding groove  113   a  and a second straight guiding groove  112   c . The third protrusions  115   a  are positioned at an end of the cam barrel  115  towards the image side. The cam barrel  115  defines a number of first lens guiding grooves  115   b  for guiding the second lens unit  13 , a number of second lens guiding grooves  115   c  for guiding the third lens unit  14 , and a third engaging groove  115   d.  The first lens guiding grooves  115   b  are at the object side of the second lens guiding grooves  115   c.  The third engaging groove  115   d  extends around the circumference of the cam barrel  115 , at an end of the cam barrel  115  towards the image side. The cam barrel  115  includes a number of connecting blocks  115   e  each formed between a second protrusion  115   a  and the outer surface of the cam barrel  115 . The connecting blocks  115   e  each include a second engaging block corresponding to a second engaging groove  114   c.    
         [0030]    The outer diameter of the inner guiding barrel  116  is less than the inner diameter of the cam barrel  115 . Referring also to  FIG. 7 , the inner guiding barrel  116  defines a number of through sixth straight guiding grooves  116   a  corresponding to the number of first lens guiding grooves  115   b  and a number of through seventh straight guiding grooves  116   b  corresponding to the number of second lens guiding grooves  115   c . The inner guiding barrel  116  includes a second stop plate  116   c  formed on an end thereof towards the image side. The second stop plate  116   c  includes a number of fourth protrusions  116   e  formed on a peripheral edge thereof corresponding to the number of fourth straight guiding grooves  113   f.  The inner guiding barrel  116  further includes a number of third engaging blocks  116   d  corresponding to the number of third engaging grooves  115   d.  The third engaging blocks  116   d  are formed on an outer surface of the inner guiding barrel  116  near the second stop plate  116   c.    
         [0031]    Referring also to  FIG. 8 , the first lens unit  12  includes a first lens group  121  and a first lens holder  122  for holding the first lens group  121 . The first lens holder  122  includes a number of fifth protrusions  122   a  corresponding to the number of fifth straight guiding grooves  114   b.  The fifth protrusions  122   a  are formed on an outer surface of the first lens holder  122  and at an end of the first lens holder  122  towards the image side. The first lens holder  122  defines a number of inclined cutouts  122   b  in an end surface thereof facing toward the image side. The inclined cutouts  122   b  correspond with the connecting blocks  115   e.    
         [0032]    The second lens unit  13  includes a second lens group  131  and a second lens holder  132  for holding the second lens group  131 . The second lens holder  132  includes a number of sixth protrusions  132   a  corresponding to the number of sixth straight guiding grooves  116   a  and the first lens guiding grooves  115   b.  The sixth protrusions  132   a  are formed on an outer surface of the second lens holder  132  at an end of the second lens holder  132  towards the image side. 
         [0033]    The third lens unit  14  includes a third lens group  141  and a third lens holder  142  for holding the third lens group  141 . 
         [0034]    Referring to  FIG. 9  and  FIG. 10 , the third lens holder  142  includes a movable barrel  1421  to carry the third lens group  141  along the optical axis, a first slidable member  1422  configured to carry the third lens group  141  along a first direction substantially perpendicular to the optical axis, and a second slidable member  1423  configured to carry the third lens group  141  along a second direction which is substantially perpendicular to the optical axis and substantially parallel to the first direction. 
         [0035]    The movable barrel  1421  includes a main portion  1421   a  with a central opening (not labeled) defined therein, a first coil  1421   b,  a first Hall element  1421   c,  and a first guiding bar  1421   d.  The main portion  1421   a  includes a number of seventh protrusions  1421   e  corresponding to the number of seventh straight guiding grooves  116   b  and second lens guiding grooves  115   c.  The seventh protrusions  1421   e  are formed on an outer surface of the main portion  1421   a  at an end of the main portion  1421   a  towards the object side. The first coil  1421   b  is fixed on the main portion  1421   a  and is configured for driving the first slidable member  1422  along the first direction. The first Hall element  1421   c  is fixed on the main portion  1421   a  near the first coil  1421   b  and is configured for detecting any movement of the first slidable member  1422  in the first direction. The first guiding bar  1421   d  is positioned on the main portion  1421   a  and has a lengthwise direction substantially parallel to the first direction and is configured for guiding the first sliding member  1422  to slide along the first direction. Positioned on the movable barrel  1421  is a first auxiliary guiding bar  1421   f  substantially parallel to the first guiding bar  1421   d.  The first auxiliary guiding bar  1421   f  is shorter than the first guiding bar  1421   d.    
         [0036]    The first sliding member  1422  includes a first frame  1422   a,  a second coil  1422   b,  a second Hall member  1422   c,  a first magnet  1422   d  and a second guiding bar  1422   e.  The first frame  1422   a  includes a first side S 1 , a second side S 2 , a third side S 3  and a fourth side S 4 . The sides S 1 , S 2 , S 3  and S 4 , are connected end to end. The first side S 1  is substantially parallel to the third side S 3 , the second side S 2  is substantially parallel to the fourth side S 4 , and the first side S 1  is substantially perpendicular to the fourth side S 4 . The first side S 1 , the second side S 2 , the third side S 3  and the fourth side S 4  cooperatively define a central opening O therebetween. The first frame  1422   a  includes a first yoke portion  1422   f  formed on a peripheral surface of the first side S 1  and a first auxiliary yoke portion  1422   h  formed on a peripheral surface of the third side S 3 . The first frame  1422   a  defines a first mounting groove  1422   g  in the second side S 2  corresponding to the first magnet  1422   d.  The second coil  1422  is fixed on the first side S 1  and is configured for driving the second slidable member  1423  to slide along the second direction. The second Hall member  1422   b  is fixed on the first side S 1  near the second coil  1422  and is configured for detecting any movement of the second slidable member  1423  along the second direction. The first magnet  1422  is substantially cuboid. Referring to  FIG. 11 , in this embodiment, the first magnet  1422  includes two north (N) poles and two south (S) poles. The N poles and the S poles alternate as if around a clock face, where the first and third quarters hold a N pole, and the second and fourth quarters hold a S pole. The second guiding bar  1422   e  is substantially parallel to the second side S 2 , and an end of the second guiding bar  1422   e  is connected to the first side S 1  and another end to the third side S 3 . The second guiding bar  1422   e  is configured for guiding the second slidable member  1423  to slide along the second direction. The first frame  1422   a  further includes a second auxiliary guiding bar  1422   i  formed on an inner surface of the fourth side S 4  substantially parallel to second guiding bar  1422   e.  The second auxiliary guiding bar  1422   i  is shorter than the second guiding bar  1422   e.    
         [0037]    The second slidable member  1423  includes a second frame  1423   a  and a second magnet  1423   b.  The second frame  1423   a  includes a first side S 11 , a second side S 12  and a third side S 13 . The first side S 11 , second side S 12  and third side S 13  are connected end to end. The first side S 11 , second side S 12  and third side S 13  cooperatively define a fixing hole H therebetween for receiving and fixing the third lens group  141  therein. The first side S 11  is substantially perpendicular to the second side S 12 , and the third side S 13  is arc-shaped. The second frame  1423   a  includes a second yoke portion  1423   c  formed on a peripheral surface of the first side S 11  and a second auxiliary yoke portion  1423   e  formed on a peripheral surface of the third side S 13  near the second side S 12 . The second slidable member  1423  defines a second mounting groove  1423   d  in the second side S 12  corresponding to the second magnet  1423   b.  The second magnet  1423   b  has a structure similar to that of the first magnet  1422   d.    
         [0038]    In assembly of the third lens unit  14 , referring to  FIG. 1 , the first magnet  1422   d  is fixedly received in the first mounting groove  1422   g,  the first yoke portion  1422   f  is a sliding fit on the first guiding bar  1421   d , and the first auxiliary yoke portion  1422   h  is a sliding fit on the first auxiliary bar  1421   f.  The second magnet  1423   b  is fixedly received in the second mounting groove  1423   d,  the second yoke portion  1423   c  is a sliding fit on the second guiding bar  1422   e,  and the second auxiliary yoke portion  1423   e  is a sliding fit on the second auxiliary guiding bar  1422   i.  In the assembled third lens unit  14 , the first Hall member  1421   c  and the first coil  1421   b  are aligned with the first magnet  1422   d  along the optical axis, and the second Hall member  1422   c  and the second coil  1422   b  are aligned with the second magnet  1423   b  along the optical axis. 
         [0039]    Referring again to  FIG. 1 , the fourth lens unit  15  includes a fourth lens group  151  and a fourth lens holder  152  for holding the fourth lens group  151 . The fourth lens holder  152  carries the fourth lens group  151  along the optical axis of the zoom lens  10  to correctly focus the images of the objects onto the image sensing module  20 . 
         [0040]    The image sensing module  20  is configured for receiving and sensing images captured by the zoom lens  10 . The image sensing module  20  can be charge coupled device (CCD) module or complementary metal oxide semiconductor (CMOS) module. 
         [0041]    The first driving unit  30  drives the zoom lens  10  in or out. The first driving unit  30  includes a driving motor  31  and a transmission portion  32 . The transmission portion  32  transmits the rotation of the driving motor  31  into moving the zoom lens  10 . In this embodiment, the transmission portion  32  employs a gear-driven mechanism. The transmission portion  32  includes a driving gear  321  corresponding to the teeth portion  112   b  of the gear barrel  112 , for driving the gear barrel  112 . 
         [0042]    The second driving portion  40  is configured for driving the fourth lens unit  15  along the optical axis. 
         [0043]    Referring to  FIG. 1 ,  FIG. 12  and  FIG. 13 , in assembly of the imaging device  100 , the gear barrel  112  is put into the fixed barrel  111 , the first protrusions  112   a  are inserted into the first inclined guiding grooves  111   b,  and a part of the teeth portion  112   b  faces toward the entrance  111   c.  The outer guiding barrel  113  is put into the gear barrel  112 , the first stop plate  113   b  resists on an end surface of the gear barrel  113  towards the image side, the first engaging blocks  112   d  are inserted into the first engaging groove  113   d,  and the second protrusions  113   c  mate with the corresponding first straight guiding grooves  111   a.  The front guiding barrel  114  is put into the outer guiding barrel  113 , the guiding blocks  114   a  are manipulated into the corresponding third straight guiding grooves  113   e.  An object side end of the cam barrel  115  is put into the front guiding barrel  114 , the third protrusions  115   a  pass through the corresponding second inclined guiding grooves  113   a  and insert themselves into the corresponding second straight guiding grooves  112   c,  and the second engaging blocks  115   f  are inserted into the corresponding second engaging grooves  114   c.  The first lens holder  122  is mounted between the cam barrel  115  and the front guiding barrel  114 , the fifth protrusions  122   a  mate with the corresponding fifth straight guiding grooves  114   b,  and the connecting block  115   e  goes through the corresponding inclined cutouts  122   b  and resist on the first lens holder  122 . An object side end of the inner guiding barrel  116  is put into the cam barrel  115 , the second stop plate  116   c  resists on an image side end surface of the cam barrel  115 , the third engaging blocks  116   d  engage with the corresponding third engaging grooves  115   d,  and the fourth protrusions  116   e  are inserted into the corresponding fourth straight guiding grooves  113   f.  The second lens holder  132  is received in the inner guiding barrel  116 , the sixth protrusions  132   a  go through the corresponding sixth straight guiding grooves  116   a  and insert themselves into the corresponding first lens guiding grooves  115   b.  The third lens holder  142  is received in the inner guiding barrel  116 , the seventh protrusions  1421   e  go through the corresponding seventh straight guiding grooves  116   b  and mate with the corresponding second lens guiding grooves  115   c.  The fourth lens unit  15  is received in the fixed barrel  111  and is movable along the optical axis. 
         [0044]    In the assembled zoom lens  10 , the gear barrel  112  and the cam barrel  115  can rotate about the optical axis and so move along the optical axis relative to the fixed barrel  111  and the outer guiding barrel  113 . The inner guiding barrel  116 , the front guiding barrel  114 , the first lens unit  12 , the second lens unit  13  and the third lens unit  14  can move along the optical axis relative to the fixed barrel  111 . 
         [0045]    The assembled zoom lens  10  is aligned with the image sensing module  20  along the optical axis, and the fixed barrel  111  is fixedly connected to the imaging module  20 . The first driving unit  30  and the second driving unit  40  are fixed on the image sensing module  20 . The driving gear  321  is inserted into the fixed barrel  111  through the entrance  111   c  and meshes with the teeth portion  112   b  of the gear barrel  112 . 
         [0046]    In use, the imaging device  100  zooms in and zooms out by means of the movements of the first lens unit  12 , the second lens unit  13  and the third lens unit  14  along the optical axis. In detail, the first driving unit  30  drives the gear barrel  112  to rotate about the optical axis, the first protrusions  112   a  move along the first inclined guiding grooves  111   b,  thus the gear barrel  112  moves along the optical axis at the same time. During this movement, the gear barrel  112  carries the outer guiding barrel  113  along the optical axis. The cam barrel  115  rotates about the optical axis driven by the gear barrel  112 , at the same time, the second protrusions  115   a  move along the second inclined guiding grooves  113   a  to drive the cam barrel  115  along the optical axis. During this movement, the cam barrel  115  drives the inner barrel  116  and the first lens holder  122  along the optical axis. The second lens holder  132  and the third lens holder  142  move along the optical axis under the driving of, and limitation of, the cam barrel  115  and the inner guiding barrel  116 . 
         [0047]    The imaging device  100  also moves the third lens group  141  along the first direction and/or the second direction to correct image blur due to any shaking of the imaging device  100  during the capturing of images. 
         [0048]    In detail, the first magnet  1422   d  forms a first magnetic field around the first coil  1421   b  and the first Hall member  1421   c,  and the second magnet  1423   b  forms a second magnetic field around the second coil  1422   b  and the second Hall member  1422   c . If no shaking occurs, the intensities of the first magnetic field and the second magnetic field are constant. If any shakes happen, the first slidable member  1422  may deviate from its original position along the first direction, and/or the second slidable member  1423  may deviate from its original position along the second direction. 
         [0049]    If the first slidable member  1422  deviates along the first direction, the intensity of the first magnetic field around the first Hall member  1421   c  will accordingly change, then the first Hall member  1421   c  can detect the changing of the intensity of the first magnetic field around the first Hall member  1421   c.  Therefore, the amount of any deviation of the first slidable member  1422  along the first direction can be calculated according the changing of the intensity of the first magnetic field detected by the first Hall member  1421   c,  and a compensating offset can be calculated for the first slidable member  1422 . If the second slidable member  1423  deviates along the second direction, the intensity of second magnetic field around the second Hall member  1423   c  will accordingly change, then the second Hall member  1422   c  can detect the changing of the intensity of the second magnetic field around the second Hall member  1422   c.  Therefore, any deviation of the second slidable member  1423  along the second direction can be calculated according to the changing of the intensity of the second magnetic field detected by the second Hall member  1422   c,  and a compensating offset for the second slidable member  1423  can be calculated. 
         [0050]    The first coil  1421   b  can produce a magnetic force to alter the natural position(s) of the first slidable member  1422  so as to compensate for the deviation, by outputting a current calculated to negate the deviation of the first slidable member  1422 . The second coil  1422   b  can function in exactly the same manner in relation to the second slidable member  1423 . By these means, image blur because of any shaking of the image device  100  can be prevented. 
         [0051]    Particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.