Abstract:
The invention provides a zoom lens, including a plurality of lens groups. When the zoom lens is in operation, the plurality of lens groups are aligned on a common optic axis, and the zoom lens forms a first plane and a second plane conjugated with the first plane. To retract the zoom lens, at least one of the lens groups is rotated around an axis perpendicular to the common optical axis and toward the first plane, and at least one of the rest of the lens groups is moved toward the second plane along the common optical axis. As a result, overall length of the zoom lens is shortened when it is retracted to obtain the miniaturization.

Description:
[0001]    This Application claims priority of Taiwan Patent Application No. 097115917, filed on Apr. 30, 2008, the entirety of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a zoom lens, and in particular, to zoom lens applied to miniaturized electronic devices. 
         [0004]    2. Description of the Related Art 
         [0005]    With technological progress, portable electronic devices, such as notebooks, mobile phones, personal digital assistances (PDAs) or portable projectors, are being integrated with optoelectronic technology. For example, a mobile phone may be integrated with optical lenses to form a camera phone. Camera phones not only require fine image quality, but also a relatively small size and low cost. 
         [0006]    For miniaturization of lenses and low cost, aspheric lenses are usually selected for portable electronic devices with optoelectronic technology, as a preferred lens. The aspheric lenses are utilized to eliminate spherical aberration produced by spherical lenses. In addition, a single aspheric lens can replace multiple spherical lenses to compensate for aberration, and further simplify the optical design within the lenses, reducing size and weight of the lenses. However, further miniaturization of aspheric lenses has been limited, especially for lens requiring a wide zoom range. 
         [0007]    In Japanese Patent No. 3742645, the storage length of a collapsible lens can be further shortened by shifting a portion of the zoom lens in an optical direction. Meanwhile, in Japanese Laid-Open No. 2004-341154, instead of shifting the lens groups, the cam barrel for extending the lenses is designed to be shortened. 
         [0008]    Although methods for miniaturizing the zoom lens have been disclosed by various publications, the eccentricity of lenses when the zoom lens is in operation has not been satisfactorily dealt with. Therefore, a method for minimizing the zoom lens is required to avoid the eccentricity of lenses when the zoom lens is in operation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The invention provides a zoom lens, and in particular, a shortened zoom lens with characteristics of low cost, low tolerance sensitivity, short length and high resolution. 
         [0010]    Accordingly, the zoom lens comprises a plurality of lens groups. When the lens is in operation, the plurality of lens groups are aligned on a common optic axis and the zoom lens forms a first plane and a second plane conjugated with the first plane. When retracting the zoom lens, at least one of the lens groups is rotated around an axis perpendicular to the common optical axis to be off line with the common optical axis, and toward the first plane and at least one of the rest of the lens groups is moved toward the second plane along the common optical axis. 
         [0011]    Accordingly, another zoom lens is provided. The zoom lens comprises N lens groups, from the first lens group to the N lens group, characterized by when the zoom lens is in operation, the N lens groups are aligned on a common optical axis, and the zoom lens forms a first plane and a second plane conjugated to the first plane. When retracting the zoom lens, any of the lens groups except for the first lens group is rotated around an axis perpendicular to the common optical axis to be off line with the common optical axis, and toward the first plane, and at least one of the rest of the lens groups is moved from the first plane toward the second plane along the common optical axis. 
         [0012]    The zoom lens comprises a seat adjacent to the second plane, a protrusion protruding from the seat toward the first plane and extending in parallel with the common optical axis, at least one rotating shaft of a frame disposed perpendicular to the common optical axis, and a gear set, with a cam, disposed on the rotating shaft. When retracting the zoom lens, the cam abuts the protrusion to rotate the lens group around the rotating shaft toward the first plane. 
         [0013]    The zoom lens further comprises an outer frame assembled with the rotating shaft. When retracting the zoom lens, the outer frame moves toward the seat with rotation, and moves the cam to abut the protrusion. 
         [0014]    The zoom lens further comprises an elastic member. When the lens groups are rotated around the axis perpendicular to the common axis to be off line with the common axis, the elastic member is accumulated with elastic potential energy. When the zoom lens is in operation, at least one of the lens groups is rotated to align with the common optical axis by the elastic member. Preferably, the elastic member is a torsion spring disposed on the rotating shaft and abutting the outer frame. When retracting the zoom lens, at least one of the lens groups rotates around the rotating shaft toward the first plane and the torsion spring is accumulated with elastic potential energy, such that the torsion spring releases energy to rotate the lens group to align with the common optical axis when the zoom lens is in operation. 
         [0015]    The zoom lens further comprises a fixing tube assembled with the seat, a rotary tube disposed in the fixing tube, rotating around and moving along the common optical axis, and a straight tube inrotatably disposed in the rotary tube and moving along the common optical axis. The fixing tube comprises an inner surface with a first cam recess formed thereon, and the first cam recess is not in parallel with the common optical axis. The rotary tube is rotated and moved by the first cam recess. The rotary tube comprises an inner surface with a second cam recess formed thereon, and the second cam recess is not in parallel with the common optical axis. 
         [0016]    The outer frame of the zoom lens further comprises a cam latch gearing with the second cam recess and the third cam recess simultaneously, allowing the outer frame to move between the first plane and the second plane with rotation. 
         [0017]    The zoom lens further comprises a motor driving the rotary tube to rotate and move. 
         [0018]    In the zoom lens, at least one of the lens groups is rotated around the rotating shaft toward the first plane, and an optical axis thereof is perpendicular to the common optical axis. 
         [0019]    Compared to the conventional design, the zoom lens of the invention minimizes its length by rotating at least one of the lens groups toward the first plane when it is retracted, successfully achieving miniaturization. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0021]      FIGS. 1A and 1B  are schematic views of a zoom lens of the invention showing an extended status and a retracted status, respectively; 
           [0022]      FIG. 2  is an exploded view of the zoom lens of an embodiment of the invention; 
           [0023]      FIG. 3  is a schematic view of the zoom lens viewed from a first plane to the second plane, wherein the zoom lens of the embodiment is held with a seat, a second lens group and an aperture diaphragm; 
           [0024]      FIG. 4A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens before retraction; 
           [0025]      FIG. 4B  is a sectional view from line B-B′ of  FIG. 3 , and it is viewed from A′ to A to show the zoom lens before retraction; 
           [0026]      FIG. 4C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens before retraction; 
           [0027]      FIG. 5A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens being retracted; 
           [0028]      FIG. 5B  is a sectional view from line B-B′ of  FIG. 3 , and it is viewed from A′ to A to show the zoom lens being retracted; 
           [0029]      FIG. 5C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens being retracted; 
           [0030]      FIG. 6A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens after retraction; 
           [0031]      FIG. 6B  is a sectional view from line B-B′ of  FIG. 3 , and it is viewed from A′ to A to show the zoom lens after retraction; and 
           [0032]      FIG. 6C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens after retraction. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]      FIGS. 1A and 1B  are schematic views of a zoom lens of the invention showing an extended status and a retracted status, respectively. As shown in  FIGS. 1A and 1B , the zoom lens comprises four lens groups as arranged as follows: a first lens group  1 , a second lens group  2 , an aperture diaphragm S, a third lens group  3  and a fourth lens group  4 . When the zoom lens is in operation, the lens groups are aligned on a common optical axis OA, and the zoom lens forms a first plane P 1  and a second P 2  conjugated with the first plane P 1 . For example, when the zoom lens is applied to a camera, the first plane P 1  corresponds to an object side while the second plane P 2  corresponds to an image side. When the zoom lens is applied to a projector, the first plane P 1  corresponds to a magnifying side while the second plane P 2  corresponds to a reduction side. When the zoom lens is in operation, at least one of the lens groups move along the common optical axis OA. 
         [0034]    When retracting the zoom lens, at least one of the lens groups rotates around an axis perpendicular to the common optical axis OA and toward the first plane P 1 , at least one of the rest of the lens groups moves in a direction parallel to the common optical axis OA from the first plane P 1  toward the second plane P 2 . Referring to  FIG. 1A , the third lens group  3  first moves off line with the common optical axis OA, then rotates around an axis perpendicular to the common optical axis OA, and finally moves toward the first plane P 1 . Otherwise, referring to  FIG. 1B , the third lens group  3  directly rotates around an axis perpendicular to the common optical axis OA, and moves simultaneously toward the first plane P 1 . 
         [0035]    Referring to  FIGS. 1A and 1B , when the zoom lens of the embodiment is retracted, the third lens group  3  has been rotated off line with the common optical axis OA and moved toward the first plane P 1 , such that the first lens group  1 , the second lens group  2  and the aperture diaphragm S are able to move toward the second plane P 2 , allowing the second lens group  2  and the fourth lens group  4  to be adjacent to each other. As a result, the length of the retracted zoom lens is significantly reduced. 
         [0036]      FIG. 2  is an exploded view of the zoom lens of an embodiment of the invention. Referring to  FIG. 2 , the zoom lens comprises a first lens group G 1 , a second lens group G 2 , a third lens group G 3 , a seat  62 , a fixing tube  41 , a first straight tube  30 , a first rotary tube  29 , a second straight tube  35  and a second rotary tube  34 . The aperture diaphragm S is disposed between the first lens group G 1  and the second lens group G 2 . The first lens group G 1  comprises a first lens L 1 , a second lens L 2 , a third lens L 3  and a first frame  19 , wherein the first lens L 1 , the second lens L 2  and the third lens  13  are accommodated and fixed in the first frame  19 . The first frame  19  comprises a first cam latch  191  on an outer periphery thereof. 
         [0037]    The second lens group G 2  comprises a first lens L 4 , a fifth lens L 5 , a second frame  24 , a second outer frame  20 , a torsion spring  21 , a rotating latch shaft  22  and a gear set  23 . The fourth lens L 4  and the fifth lens L 5  are accommodated and fixed in the second frame  24 . The second frame  24  comprises a pair of support arms  241   a ,  241   b . When the second frame  24  is involved in the operation, the pair of support arms  241   a ,  241   b  are substantially parallel to the common optical axis OA. The second outer frame  20  comprises a second cam latch  201 , a shaft hole  202  and a fixing arm  203 . The rotating latch shaft  22  passes through the shaft hole  202  and the torsion spring  21  and is fixed to one of the support arms  241   a . In the embodiment, the other support arm  241   b  connects with the second outer frame  20  in the same fashion of the connection between the outer frame  20  and the support arm  241   a , allowing the second frame  24  to rotate around the axis perpendicular to the common optical axis OA by the rotating latch shaft  22 . The gear set  23  comprises a first sector gear  231  and a second sector gear  232 , wherein the second sector gear  232  comprises a cam  2321 . The first sector gear  231  is fixed on the support arm  241   b  and the second sector gear  232  is rotatably disposed on the fixing arm  203  by a latch  2322 , allowing the first sector gear  231  to gear with the second sector gear  232 . 
         [0038]    The third lens group G 3  comprises a sixth lens L 6  and a first driving module  31 . Driven by the driving module  31 , the sixth lens L 6  moves along the common optical axis OA to adjust the focus. 
         [0039]    The seat  62  comprises a protrusion  621  extending in parallel with the common optical axis OA. The fixing tube  41  is assembled with the seat  62 . The fixing tube  41  comprises a first cam recess  411 , formed on an inner surface of the fixing tube  41 , in parallel with the common optical axis OA and a second cam recess  412  not in parallel with the common optical axis OA. The first rotary tube  29  comprises a gear  291  disposed on a periphery, adjacent to the seat  62 , of an outer surface of the first rotary tube  29 , and a third cam recess  292  and a fourth cam recess  293 , formed on an inner surface of the first rotary tube  29 , in parallel with the common optical axis OA. Additionally, a third cam latch  294 , disposed on the periphery, adjacent to the seat  62 , of the outer surface of the first rotary tube  29  gears with the second cam recess  293 , allowing the first rotary tube  29  to rotate around and move along the common optical axis OA within the fixing tube  41 . 
         [0040]    The first straight tube  30  comprises a fifth cam recess  301 , formed on an inner surface of the first straight tube  30 , not in parallel with the common optical axis OA and a sixth cam recess  302 , formed on the inner surface of the first straight tube  30 , in parallel with the common optical axis OA. The first straight tube  30  comprises a fourth cam latch  303  disposed on a periphery, adjacent to the seat  62 , of an outer surface of the first straight tube  30  and a fifth cam latch  304 , disposed on a periphery, away from the seat  62 , of the outer surface of the first straight tube  30 . The fifth cam latch  304  gears with the third cam recess  292  and then engages with a periphery  295 , away from the seat  62 , of an inner surface of the first rotary tube  29 . The fourth cam latch  303  gears with the first cam recess  411  of the fixing tube  41 . Therefore, when the first rotary tube  29  rotates around and moves along the common optical axis OA within the fixing tube  41 , the first rotary tube  29  moves the first straight tube  30  along the common optical axis OA. 
         [0041]    The second rotary tube  34  comprises a seventh cam recess  345  and an eighth cam recess  346 , formed on an inner surface of the second rotary tube  34 , not in parallel with the common optical axis OA. The second rotary tube  34  further comprises a sixth cam latch  341  disposed on a periphery, adjacent to the seat  62 , of an outer surface of the second rotary tube  34 . The fifth cam recess  301 , a groove, allows the sixth cam latch  341  to pass therethrough and to gear with the fourth cam recess  293 . Therefore, when the first rotary tube  29  rotates around the common optical axis OA, the second rotary tube  34  is driven to rotate around the common optical axis OA. 
         [0042]    The second straight tube  35  comprises a ninth cam recess  353  and a tenth cam recess  354 , formed on an inner surface of the second straight tube  35 , in parallel with the common optical axis OA. The second straight tube  35  further comprises a seventh cam latch  352  disposed on a periphery, adjacent to the seat  62 , of an outer surface of the second straight tube  35 . The seventh cam latch  352  gears with the sixth cam recess  302 , such that when the first straight tube  30  move along the common optical axis OA, the second straight tube  35  is driven to move along the common optical axis OA. 
         [0043]    The ninth cam recess  353 , a groove, allows the first cam latch  191  of the first frame  19  to pass therethrough and to gear with the seventh cam recess  345 . The tenth cam recess, a groove, allows the second cam latch  201  of the second outer frame  20  to pass therethrough and to gear with the eighth cam recess  346 . 
         [0044]    When the zoom lens is in operation, the first rotary tube  29  drives the second rotary tube  34  to rotate around the common optical axis OA, and the first lens group G 1  is moved along the common optical axis OA by the first cam shaft  191 , the ninth cam recess  353  and the seventh cam recess  345 , and the second lens group G 2  is moved along the common optical axis OA by the second cam latch  201 , the tenth cam recess  354  and the eighth cam recess  346 . 
         [0045]    The second driving module  50 , disposed on the outer surface of the fixing tube  41 , gears with the gear  291  of the first rotary  29 . When the zoom lens is in operation, the second driving module  50  drives the first rotary  29  to rotate around the common optical axis OA. 
         [0046]      FIG. 3  is a schematic view of the zoom lens viewed from a first plane to the second plane, wherein the zoom lens of the embodiment is held with the seat, the second lens group and the aperture diaphragm. 
         [0047]      FIG. 4A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens before retraction.  FIG. 4B  is a sectional view from line B-B′ of  FIG. 3 , and it is viewed from A′ to A to show the zoom lens before retraction.  FIG. 4C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens before retraction. Referring to  FIGS. 4A-4C , before retraction of the zoom lens of the embodiment, the cam  2321  of the second sector gear  232  of gear set  23  abuts the protrusion  621  of the seat  62 . 
         [0048]      FIG. 5A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens being retracted.  FIG. 5B  is a sectional view from line B-B′ of  FIG. 3 , and it is viewed from A′ to A to show the zoom lens being retracted.  FIG. 5C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens being retracted. Referring to  FIGS. 5A-5C , when retracting the zoom lens of the embodiment, the cam  2321  of the second sector gear  232  of gear set  23  abuts the protrusion  621  of the seat  62 , allowing the second sector gear  232  to rotate the second frame  24  around the rotating latch shaft  22  toward the first plane. 
         [0049]      FIG. 6A  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B′ to B to show the zoom lens after retraction.  FIG. 6B  is a sectional view from line B-B′ of FIG.  3 , and it is viewed from A′ to A to show the zoom lens after retraction.  FIG. 6C  is a sectional view from line A-A′ of  FIG. 3 , and it is viewed from B to B′ to show the zoom lens after retraction. Referring to  FIGS. 6A-6C , when the zoom lens of the embodiment has been retracted, the second frame  24  has been rotated off line with the common optical axis. The optical axis of the second frame  24  is substantially perpendicular to the common optical axis. 
         [0050]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.