Abstract:
A zoom lens assembly includes an optical system forming an optical axis and having at least one lens group, a base member ( 1 ), a macro ring member ( 2 ) rotatably engaged with the base member for accomplishing both zooming and focusing operations, a lens holder ( 3 ) received in the macro ring member and having the at least one lens group received therein, a resilient member ( 4 ) compressively engaged with the lens holder, and an interengaging means ( 13, 21; 16, 25 ) provided between the macro ring member and the base member. The macro ring member has a driving member ( 22, 27 ) disposed thereon for manual manipulating. When the driving member is manipulated, the macro ring member is rotated and moved along the optical axis relative to the base member by the action of the interengaging means, and thus the focal length of the optical system is varied for effecting both normal photography and macro photography.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a zoom lens assembly capable of effecting both macro (close-up) photography and normal photography, and particularly relates to such a zoom lens assembly of a simple structure.  
         [0003]     2. Description of Prior Art  
         [0004]     It is well known that, due to the limited space, photographing lenses used in camera phones have dimensions much smaller than those in photographic cameras, video cameras and digital cameras. To obtain the best image quality, camera phones generally employ fixed focal length lenses. However, since the focal length is fixed rather than adjustable, the focus range for such fixed focal length lenses is limited, and thus it would be unavailable to take the scenes out of the focus range or take them ambiguously.  
         [0005]     To address the above problem, camera phones with zoom lens for effecting macro photography have been designed. Various focusing devices of zoom lenses capable of focusing to a macro photographing distance range just beyond the close distance position in a normal photographing distance range which enables zoom magnification change have been proposed and are already known. These focusing devices are disclosed in U.S. Pat. Nos. 4,720,182; 4,806,000; 6,778,333 and U.S. Pat. Pub. No. 20040263999.  
         [0006]     A zoom lens in which zoom magnification change and focusing from the normal photography area to the macro area can be accomplished by an operation member is also known, for example, from U.S. Pat. No. 4,448,496. In the above-described prior art, there is shown a zoom lens in which focusing in the normal photography area is accomplished by rotating an operating member and subsequently focusing in the macro area can be accomplished by further rotation of the operating member beyond the normal photography area. However, the mechanical operating device for the above-described conventional zoom lens is rather complicate and thus occupies a large space, which deviates from the miniaturization trend of modern consuming products such as camera phones.  
         [0007]     The components of a conventional zoom lens assembly with macro photography capabilities are illustrated in  FIGS. 1-2 . The conventional zoom lens assembly includes a base  6 , a macro ring  7 , a focus ring  8 , a lens holder  9 , a helicoidal spring  10 , an outer cap  11 , a pair of bolts  12  and an image sensing element  13 . The base  6  has an annular socket  61  formed at a central portion thereof for supporting the macro ring  7  therearound and for receiving the focus ring  8  and the lens holder  9  therein. A pair of opposing guide posts  62  and a pair of opposing retention portions  63  are formed at corners of the base  6 . Each retention portion  63  defines a threaded hole  65  therein for engaging with the bolt  12 , thereby assembling the components into a unit. An opening  66  is defined in the bottom of the base  6  in communication with the annular socket  61  chamber. Three inverted U-shaped supporters  64  are arranged at equal intervals around the outer periphery of the annular socket  61 . The macro ring  7  has a bottom surface  72 , three projections  71  downwardly projecting from the bottom surface  72 , and a transition slope  74  connecting the bottom of each projection  71  with the bottom surface  72 . A driving arm  73  projects outwardly from the outer periphery of the macro ring  7 . The focus ring  8  includes a barrel  81  for receiving the lens holder  9  therein, a top rim  82  having an outer diameter larger than that of the barrel  81 , and a pair of opposite guide portions outwardly projecting from the top rim  82  and each defining a semicircular guide slot  84  therethrough. The image sensing element  13  is a CCD (Charge-Coupled Device) sensor or a CMOS (Complimentary Metal-Oxide Semiconductor) sensor.  
         [0008]     A side view of the conventional zoom lens assembly in an assembled state is shown in  FIGS. 3 and 4 . It should be noted that, for facilitating description of the operation process of the mechanical operating device of the conventional zoom lens assembly, the helicoidal spring  10 , the outer cover  11 , the bolts  12  and the image sensing element  13  are omitted from  FIGS. 3 and 4 . As shown in  FIGS. 3 and 4 , the macro ring  7  is mounted over the annular socket  61  of the base  6 . In a normal photographing position as shown in  FIG. 3 , the bottom surface  72  of the macro ring  7  is supported on the supporters  64  of the base  6 . The focus ring  8  with the lens holder  9  received therein is inserted into the annular socket  61  with the rim  82  thereof abutting against the top edge of the macro ring  7 . The semicircular guide slots  84  of the focus ring  8  receive corresponding guide posts  62  of the base  6  therein so as to allow upward and downward movements of the focus ring  8 . When macro photography is desired, the driving arm  73  of the macro ring  7  is rotated leftwardly as viewed from  FIG. 3  from the normal photographing position of  FIG. 3  to the macro photographing position of  FIG. 4 , where the bottoms of the projections  71  of the macro ring  7  are supported on the supporters  64  of the base  6 . That is, the macro ring  7  rotates in a certain angle whereby the slope  74  slides over the supporter  64  and then the bottom of the projection  71  engages with the supporter  64 . As a result, the focus ring  8  coupled to the macro ring  7  and the lens holder  9  received in the focus ring  8  are both upwardly moved a certain distance, whereby focus length adjustment is achieved and thus macro photography is effected. As illustrated in  FIG. 5 , in the case of a fixed position of the image plane “M” (i.e., where the image sensing element  13  is arranged) of the optical system, when the object to be photographed is at a normal distance, the lens holder  9  is located at position “L”, and a clear image A′-B′ of such an object A-B is formed on the image plane “M”. When the object to be photographed is at a close-up distance less than a normal object distance, the lens holder  9  is moved from the position “L” to position “L 1 ”, and a clear image A 1 ′-B 1 ′ of such an object A 1 -B 1  is also formed on the image plane “M”.  
         [0009]     Although the conventional zoom lens assembly as described above is capable of macro photography by the adoption of a mechanical adjustment device, it requires a number of components and thus is complex in configuration, which results in increased costs and bulky configuration of the zoom lens assembly and thus the photographic device applying such a zoom lens assembly. This deviates from the miniaturization trend of modern consuming products and thus restricts wide application of such a zoom lens assembly.  
         [0010]     Further, in the conventional zoom lens assembly as described above, there are provided both a focus ring for the normal photography and a macro ring for the macro photography (an operating member for zoom magnification change). Therefore, when photography is to be continuously effected from the normal photography area to the macro photography area or from the macro photography area to the normal photography area, the two rings must be operated cooperatively. Accordingly, the operation for focusing is complicated and quick focusing cannot be accomplished. In addition, the focusing is discontinuous and this leads to the possibility of missing the opportunity to photograph an object in motion whose distance gradually changes.  
       SUMMARY OF THE INVENTION  
       [0011]     Accordingly, one object of the present invention is to provide a compact zoom lens assembly capable of effecting both macro (close-up) photography and normal photography.  
         [0012]     Another object of the present invention is to provide a zoom lens assembly provided with a macro photography change-over device in which zooming and focusing from the normal photography area to the macro photography area can be accomplished by an operating member.  
         [0013]     To achieve the above objects, a zoom lens assembly in accordance with the present invention includes an optical system defining an optical axis, a base member, a macro operating ring member rotatably engaged with the base member for both zooming and focusing operations, a lens holder received in the macro operating ring member and adapted for receiving at least one lens group therein, and a resilient member compressively engaged with the lens holder. An interengaging means is disposed between the macro operating ring member and the base member. The macro operating ring member is rotated and moved a certain distance by the action of the interengaging means along the optical axis relative to the base member. A driving portion is provided on the macro operating ring member for effecting rotation of the macro operating ring member. In this way, focal length adjustment of the optical system can be accomplished, and thus both normal photography and macro photography can be effected.  
         [0014]     Accordingly to one embodiment of the present invention, the base member has an annular socket with a cam slot defined in the outer periphery thereof. The cam slot includes a first slot portion, and a second slot portion offset from the first slot portion in the optical axis direction. An outwardly projecting cam pin is correspondingly formed on the macro operating ring member for being received in the cam slot of the base member. The cam pin is movable between the first and second slot portions for focal length adjustment.  
         [0015]     Accordingly to another embodiment of the present invention, the base member has an annular socket with female threads formed on an inner diameter side thereof. The macro operating ring member has male threads formed on the outer periphery thereof, and an outwardly projecting driving pin for effecting rotation. The male and female threads constitute an interengaging means between the base member and the macro operating ring member, by the action of which focal length adjustment is accomplished.  
         [0016]     Accordingly to a further embodiment of the present invention, the base member has an annular socket with male threads formed on an inner diameter side thereof. The macro operating ring member has male threads formed on the outer periphery thereof, and a large-dimensioned upper flange for effecting rotation. The male and female threads constitute an interengaging means between the base member and the macro operating ring member, by the action of which focal length adjustment is accomplished. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The present invention may best be understood through the following description with reference to the accompanying drawings, in which:  
         [0018]      FIG. 1  is an exploded, perspective view of a conventional zoom lens assembly;  
         [0019]      FIG. 2  is a view similar to  FIG. 1 , but viewed from a different angle;  
         [0020]      FIG. 3  is a side view illustrating a normal photographing state of the conventional zoom lens assembly, the conventional zoom lens assembly being in an assembled state but with a spring, an outer cap and a pair of bolts thereof removed for simplicity;  
         [0021]      FIG. 4  is a side view illustrating a macro photographing state of the conventional zoom lens assembly, the conventional zoom lens assembly being in an assembled state but with a spring, an outer cap and a pair of bolts thereof removed for simplicity;  
         [0022]      FIG. 5  is a schematic view provided for explaining the focal length adjustment in the normal photography position and the macro photography position;  
         [0023]      FIG. 6  is an exploded, perspective view of a zoom lens assembly in accordance with a first embodiment of the present invention;  
         [0024]      FIG. 7  is a view similar to  FIG. 6 , but viewed from a different angle;  
         [0025]      FIG. 8  is an assembled view of  FIG. 6 ;  
         [0026]      FIG. 9  is a side view showing the zoom lens assembly of  FIG. 8  in a normal photography position;  
         [0027]      FIG. 10  is a side view showing the zoom lens assembly of  FIG. 8  in a macro photography position;  
         [0028]      FIG. 11  is an exploded, perspective view of a zoom lens assembly in accordance with a second embodiment of the present invention; and  
         [0029]      FIG. 12  is an exploded, perspective view of a zoom lens assembly in accordance with a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     Referring to  FIGS. 6 and 7 , a zoom lens assembly in accordance with a first embodiment of the present invention includes a base member  1   a , a macro operating ring member  2   a , a lens holder  3  and a resilient member  4 . The lens holder  3  receives at least one lens group therein. The at least one lens group and an image sensor  5 , such as a CCD sensor or a CMOS sensor, constitute an optical system defining an optical axis. The base member  1   a  has a rectangular base plate  10  and an annular socket  11   a  integrally formed on the base plate  10 . The annular socket  11   a  is preferably in the form of a cylinder, although other forms may also be taken. An opening  14  is defined in the base plate  10  in communication with the annular socket  11   a  chamber for receiving the image sensor  5  therein. Three latch arms  12   a  project upwardly from a top side of the annular socket  11   a  at equal intervals. A cam slot  13  is defined in the outer periphery of the annular socket  11   a  between every two adjacent latch arms  12   a . The cam slot  13  includes a guide portion  13   a  extending in the optical axis direction, and first and second opposite slot portions  13   b ,  13   c  transverse to the guide portion  13   a . The first slot portion  13   b  provides a first flat surface  13   d  at the bottom side thereof, and the second slot portion  13   c  provides a second flat surface  13   f  at the bottom side thereof. The first and second flat surfaces  13   d  and  13   f  are connected with each other via an inclined surface  13   e  right below the guide portion  13   a . Accordingly, the first and second flat surfaces  13   d  and  13   f  are offset from each other in the optical axis direction. The second flat surface  13   f  is at a level higher than that of the first flat surface  13   d.    
         [0031]     The macro operating ring member  2   a  includes a hollow cylindrical body  20   a , and three cam pins  21  extending from the outer periphery of the body  20   a  at equal intervals adjacent to the bottom of the body  20   a . One of the three cam pins  21  projects a further distance to act as a driving pin  22   a  for facilitating handling. The body  20   a  includes a first receiving portion  23   a , and a second receiving portion  24  having an inner diameter smaller than that of the first receiving portion  23   a . The lens holder  3  is substantially in the form of a hollow cylinder, and includes a first hollow cylinder portion  30 , a second hollow cylinder portion  34  having an outer diameter smaller than that of the first hollow cylinder portion  30 , and a polygonal top portion  32  formed on an upper surface  31  of the first hollow cylinder portion  30 . The second hollow cylinder portion  34  forms threads on the outer periphery thereof. A central aperture  33  is defined in the polygonal top portion  32  for allowing passage of the light that is then incident on the at least one lens groups received in the lens holder  3 . The resilient element  4  is a belleville spring that includes a first ring  41 , a second ring  42  having a diameter smaller than that of the first ring  41 , and three connecting pieces  43  arranged at equal intervals connecting the first and second rings  41 ,  42 .  
         [0032]     Also referring to  FIG. 8 , in assembly, the first and second hollow cylinder portions  30 ,  34  of the lens holder  3  are retentively received in the respective first and second receiving portions  23   a ,  24  of the macro operating ring member  2   a . The macro operating ring member  2   a  is received into the annular socket  11   a  of the base member  1   a  with the cam pins  21 ,  22   a  sliding into the transverse portions of corresponding cam slots  13  via the guide portions  13   a . The second ring  42  of the resilient member  4  abuts against the top side of the body  20   a  of the macro operating ring member  2   a , and the first ring  41  is latched with the latch arms  12   a  of the base member  1   a , whereby the resilient member  4  is compressed to exert a force on the lens holder  3  and the macro operating ring member  2   a . Thus, free upward movement of the lens holder  3  and the macro operating ring member  2   a  along the optical axis is prevented.  
         [0033]     Now referring to  FIG. 9 , when the object to be photographed is at a normal distance, the driving pin  22   a  of the macro operating ring member  2   a  is received in the first slot portion  13   b  of the cam slot  13  and engages with the first flat surface  13   d  of the first slot portion  13   b . When the object to be photographed is at a macro (close-up) distance less than the normal distance, as shown in  FIG. 10 , the driving pin  22   a  of the macro operating ring member  2   a  is actuated to move from the first slot portion  13   b  to the second slot portion  13   c  at a higher level via the inclined surface  13   e . The driving pin  22   a  engages with the second flat surface  13   f  of the second slot portion  13   c . Since the first and second flat surfaces  13   d ,  13   f  of the cam slot  13  are offset from each other in the optical axis direction, the macro operating ring member  2   a  and the lens holder  3  received in the macro operating ring member  2   a  are thus upwardly moved a predetermined distance relative to the stationary base member  1   a  along the optical axis. That is, the cam pin  21 ,  22   a  of the macro operating ring member  2   a  and the corresponding cam slot  13  of the base member  1  constitute an interengaging means, by the action of which the macro operating ring member  2   a  is moved relative to the annular socket  11   a  of the base member  1   a , whereby an axial movement of the macro operating ring member  2   a  and the lens holder  3  relative to the annular socket  11   a  is accomplished. In this manner, when the macro operating ring member  2   a  is rotated, the lens holder  3  with at least one lens group received therein is upwardly moved from the normal photography position of  FIG. 9  to the macro photography position of  FIG. 10  along the optical axis through the action of the interengaging means. In this way, the interengaging means drives the at least one lens group toward the object at a macro distance for adjusting the focal length. By the reverse operation, the lens holder  3  can be downwardly moved from the macro photography position to the normal photography position.  
         [0034]     In the embodiment as described above, the three outwardly projecting cam pins  21 ,  22   a  formed on the movable macro operating ring member  2   a  are fitted into the respective cam slots  13  defined in the annular socket  11   a  of the fixed base member  1   a  to guide the movable macro operating ring member  2   a  along the optical axis. However, it should be understandable that, the cam slots may also be defined in the movable macro operating ring member  2   a , while the cam pins that are engaged in the cam slots may be formed on an inner side of the annular socket  11   a  of the fixed base member  1   a . The driving pin  22   a  remains on the macro operating ring member  2   a.    
         [0035]     A zoom lens assembly in accordance with a second embodiment of the present invention is shown in  FIG. 11 . In this embodiment, threads  16  formed on an inner diameter side of the annular socket  11   b  of the base member  1   b  replace the cam slots  13  in the first embodiment, and threads  25   b  formed on the outer periphery of the macro operating ring member  2   b  at a lower portion replace the cam pins  21  in the first embodiment. In addition, a threaded hole  26  is defined in the macro operating ring member  2   b , and the driving pin  22   b  is formed with threads  221  at one end thereof for engaging with the threaded hole  26 . The macro operating ring member  2   b  with the lens holder  3  received therein is received in the annular socket  11   b  of the base member  1   b  by the threaded engagement between the male threads  25   b  and the female threads  16 . When the driving pin  22   b  is manipulated, the macro operating ring member  2   b  is rotated and may be upwardly moved a distance relative to the annular socket  11   b  along the optical axis by the action of the threads  16  and  25   b . Thus, the focal length of the optical system is adjusted and macro photography is effected. In this embodiment, the female threads  16  on the annular socket  11   b  and the male threads  25   b  on the macro operating ring member  2   b  constitute the interengaging means, by the action of which axial movement of the macro operating ring member  2   b  and the lens holder  3  relative to the annular socket  11   b  is accomplished, and thus both normal photography and macro photograph can be effected.  
         [0036]     A zoom lens assembly in accordance with a third embodiment of the present invention is shown in  FIG. 12 . This embodiment is different from the second embodiment in that an upper flange  27  replaces the threaded hole  26  and the driving pin  22   b  in the second embodiment, and three latch arms  12   c  each with an inward free end replace the three latch arms  12   a ,  12   b  each with an outward free end in the first and second embodiments. The three latch arms  12   c  are formed on the outer periphery of the annular socket  11   c  rather than on the top side of the annular socket  11  as in the first and second embodiments. This provides rotation space for the flange  27  that has an outer diameter larger than that of the body  20   c  of the macro operating ring member  2   c . The flange  27  is rotatable in 360 degrees, whereby the focus range of the macro operating ring member  2   c  is increased. Three cutouts  28  are defined in the outer edge of the flange  27  corresponding to the latch arms  12   c  for facilitating assembly. In this embodiment, the female threads  16  on the annular socket  11   c  and the male threads  25   c  on the macro operating ring member  2   c  constitute the interengaging means, by the action of which axial movement of the macro operating ring member  2   c  and the lens holder  3  relative to the annular socket  11   c  is accomplished, and thus both normal photography and macro photograph can be effected.  
         [0037]     In the second and third embodiments as described above, the male threads  25   b ,  25   c  and the female threads  16  that constitute the interengaging means are respectively formed on the outer periphery of the macro operating ring member  2   b ,  2   c  and the inner diameter side of the annular socket  11   b ,  11   c  of the base member  1   b ,  1   c . However, it should be understood that, the male threads and the female threads may also be respectively formed on the outer periphery of the annular socket  11   b ,  11   c  of the base member  1   b ,  1   c  and the inner diameter side of the macro operating ring member  2   b ,  2   c.    
         [0038]     As is clear from the description of the above three embodiments, the mechanical focal length adjustment device of the present zoom lens assembly only requires four components to accomplish both normal and macro photography, i.e., the base member  1 , the macro operating ring member  2 , the lens holder  3  and the resilient member  4 . Therefore, the present zoom lens assembly is of a simple structure and thus manufacturing costs can be significantly decreased. This compact design also facilitates its wide application to various consuming products such as camera phones, personal digital assistance and digital cameras with a miniaturization design. Further, in accordance with the present invention, zooming and focusing from the normal photography area to the macro photography area is accomplished by rotating a micro operating ring member rather than two cooperative operating members as in the prior art. Accordingly, the operation for focusing and zooming is facilitated and quick focusing can be accomplished.  
         [0039]     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.