Abstract:
A zoom lens barrel assembly includes: a first zoom ring comprising a first protrusion; a guide ring disposed around the first zoom ring comprising a first guide slot through which the first protrusion passes, and a second guide slot; a second zoom ring comprising a second protrusion, and movable in an axial direction; a first cylinder comprising a guide groove into which the second protrusion inserts, and a third protrusion passing through the second guide slot, and disposed between the first and second zoom rings; a second cylinder disposed around the guide ring comprising a fourth protrusion, a first groove portion into which the first protrusion inserts, and a second groove portion into which the third protrusion inserts, and supporting the first zoom ring and the first cylinder; and an external cylinder disposed around the second cylinder and comprising a third groove portion into which the fourth protrusion inserts.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This Application is a continuation application of U.S. patent application Ser. No. 13/280,575, filed Oct. 25, 2011, which claims the priority benefit of Korean Patent Application No. 10-2011-0012471, filed on Feb. 11, 2011, in the Korean Intellectual Property Office, the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Disclosed herein is a zoom lens barrel assembly, and more particularly, a zoom lens barrel assembly that implements a high magnification zooming function while having a small thickness or short length when the zoom lens barrel assembly is accommodated in a camera. 
         [0003]    An optical system having various focal distances is realized when a zoom lens barrel assembly that is able to adjust distances between lens groups is mounted in a camera. The zoom lens barrel assembly can be used to change the optical system of the camera between a wide angle lens system or a telephoto lens system so that a user can perform photographing at various viewing angles without moving. 
         [0004]    Relative positions of barrels that support lens groups must be changed to adjust distances between the lens groups. For example, five magnification zooming may be implemented using a 3-step zoom lens barrel assembly having 3 relatively movable barrels. However, such implementation increases the number of parts in the 3-step zoom lens barrel assembly. 
         [0005]    When no photographing is performed, elements of a zoom lens barrel assembly may be accommodated in a camera. In this regard, a thickness or length of the zoom lens barrel assembly may be minimized in order to realize a compact camera having a small thickness to meet market demand. 
         [0006]    Recently, a compact camera may be required to implement, for example, a high-performance five magnification zooming function, and thus a zoom lens barrel assembly in the camera must perform a high-performance zooming function while having a small thickness or short length. However, 3 relatively movable barrels must be disposed in the 3-step zoom lens barrel assembly to implement five magnification zooming. Thus, reduction of a minimum thickness of the zoom lens barrel assembly is difficult when the 3-step zoom lens barrel assembly is accommodated. 
       SUMMARY 
       [0007]    Disclosed herein is a zoom lens barrel assembly that implements a high-magnification zooming function while having a small thickness or short length when the zoom lens barrel assembly is accommodated within an optical device such as a camera. 
         [0008]    Also provided is a zoom lens barrel assembly having a reduced number of parts, as well as a zoom lens barrel assembly that implements a high-magnification zooming function while having a small thickness or short length and a reduced number of relatively moving barrels. 
         [0009]    According to an embodiment of the invention, there is provided a zoom lens barrel assembly including: a first zoom ring for supporting a first lens group and comprising a first protrusion protruding outward; a guide ring comprising a first guide slot extending in an axial direction, through which the first protrusion passes, and a second guide slot extending in a circumferential direction, and disposed around the first zoom ring; a second zoom ring for supporting a second lens group, comprising a second protrusion protruding outward, and movably disposed in the axial direction with respect to the first zoom ring; a first cylinder comprising a second zoom ring guide groove formed in an inner wall surface of the first cylinder into which the second protrusion is inserted and a third protrusion protruding outward so as to pass through the second guide slot, and disposed between the first zoom ring and the second zoom ring so as to rotate and move in the axial direction; a second cylinder comprising a fourth protrusion protruding outward, rotatably disposed around the guide ring, comprising a first groove portion into which the first protrusion passing through the first guide slot is inserted, and a second groove portion into which the third protrusion passing through the second guide slot is inserted, and movably supporting the first zoom ring and the first cylinder; and an external cylinder comprising a third groove portion into which the fourth protrusion is inserted, and disposed around the second cylinder to rotatably support the second cylinder. 
         [0010]    The zoom lens barrel assembly may further include: a guide portion disposed guiding a motion of the second zoom ring in the axial direction while the first cylinder rotates. 
         [0011]    The second zoom ring may include a cutting portion extending in the axial direction in the outside thereof, and the guide portion is disposed between the second zoom ring and the first cylinder, coupled to the cutting portion, and guides a motion of the second zoom ring in the axial direction. 
         [0012]    The second zoom ring may include a guide slot extending in the axial direction, and the guide portion is pin-shaped extending in the axial direction, inserted into the guide slot, and guides a motion of the second zoom ring in the axial direction. 
         [0013]    The second cylinder may include a gear disposed around the second cylinder and extending in the circumferential direction, and the zoom lens barrel assembly may include a driving portion coupled to the gear and for generating a driving force used to rotate the second cylinder. 
         [0014]    The zoom lens barrel assembly may further include: a base fixed to the external cylinder; and an optical device disposed in the base so that the optical device corresponds to the first lens group and the second lens group. 
         [0015]    The zoom lens barrel assembly may further include: a third lens group disposed between the optical device and the second lens group; a third zoom ring for supporting the third lens group and moving in the axial direction; and a focus driving unit coupled to the third zoom ring and generating a driving force. 
         [0016]    The second groove portion may extend in the axial direction, and the second guide slot may include a sustaining portion extending in the circumferential direction along or parallel to a boundary of one end of the guide ring and sustaining a position of the first cylinder in the axial direction with respect to the guide ring, and a changing portion inclined from an end portion of the sustaining portion toward a boundary of another end of the guide ring and for changing the position of the first cylinder in the axial direction with respect to the guide ring. 
         [0017]    The first groove portion may include a first inclination portion inclined from a boundary of one end of the second cylinder toward a boundary of another end thereof, extending in the circumferential direction, and moving the first zoom ring forward in the axial direction with respect to the second cylinder, and a second inclination portion inclined from an end portion of the first inclination portion toward the boundary of the one end, extending in the circumferential direction, and moving the first zoom ring backward in the axial direction with respect to the second cylinder. 
         [0018]    The second zoom ring guide groove may include a rectilinear portion rectilinearly extending in the axial direction from a boundary of one end of the first cylinder to a boundary of another end thereof, a backward inclination portion inclined from an end portion of the rectilinear portion toward the boundary of the one end of the first cylinder, extending in the circumferential direction, and moving the second zoom ring forward in the axial direction with respect to the first cylinder, and a forward inclination portion inclined from the backward inclination portion toward the boundary of the other end of the first cylinder, extending in the circumferential direction, and moving the second zoom ring forward in the axial direction with respect to the first cylinder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and other features and advantages of various embodiments of the invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0020]      FIG. 1  is a perspective view of a zoom lens barrel assembly, according to an embodiment of the invention; 
           [0021]      FIG. 2  is a cross-sectional perspective view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention; 
           [0022]      FIG. 3  is an exploded perspective view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention; 
           [0023]      FIG. 4  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention; 
           [0024]      FIG. 5  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 4  that is adjusted at a wide-angle lens and performs zooming, according to an embodiment of the invention; 
           [0025]      FIG. 6  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 4  that is adjusted at a telephoto-angle lens and performs zooming, according to an embodiment of the invention; and 
           [0026]      FIG. 7  is an exploded perspective view of a zoom lens barrel assembly, according to another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Hereinafter, various embodiments of the invention will be described more fully with reference to the accompanying drawings. 
         [0028]      FIG. 1  is a perspective view of a zoom lens barrel assembly according to an embodiment of the invention. Referring to  FIG. 1 , the zoom lens barrel assembly unfolds in 2 steps and performs a 5-magnification optical zooming function. 
         [0029]    The zoom lens barrel assembly includes an external cylinder  80  installed in a base  90 , a first zoom ring  20  movably disposed in the external cylinder  80 , and a second cylinder  70 . The second cylinder  70  is disposed to move forward or backward from the external cylinder  80  in an axial direction (in a Z direction). The first zoom ring  20  is disposed to move forward or backward from the second cylinder  70  in the axial direction. 
         [0030]    The zoom lens barrel assembly can perform a zooming function because the first zoom ring  20  and the second cylinder  70 , which move from the external cylinder  80  fixed in the base  90  in the axial direction, are unfolded in 2 steps. Thus, a whole thickness or length of the zoom lens barrel assembly can be reduced when the first zoom ring  20  and the second cylinder  70  are accommodated in the external cylinder  80 , thereby easily implementing a small-sized and thin-shaped camera. 
         [0031]    A driving unit  5  that generates a driving force for performing the zooming function and a focus driving unit  7  that generates a driving force for performing a focusing function are disposed in exterior surfaces of the base  90  and the external cylinder  80 . 
         [0032]      FIG. 2  is a cross-sectional perspective view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention.  FIG. 3  is an exploded perspective view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention. 
         [0033]    Referring to  FIGS. 2 and 3 , the zoom lens barrel assembly comprises the first zoom ring  20  that supports a first lens group  10 , a guide ring  30  disposed around the first zoom ring  20 , a second zoom ring  50  that supports a second lens group  40 , a first cylinder  60  disposed between the first zoom ring  20  and the second zoom ring  50 , a second cylinder  70  that is disposed around the guide ring  30 , and movably supports the first zoom ring  20  and the first cylinder  60 , and an external cylinder  80  that is disposed around the second cylinder  70 . 
         [0034]    The external cylinder  80  acts as a support structure that maintains a fixed state in the zoom lens barrel assembly. 
         [0035]    When the zoom lens barrel assembly operates and performs the zooming function, the first zoom ring  20  protrudes forward in the axial direction (in the Z direction) with respect to the second cylinder  70 . The first zoom ring  20  has a cylindrical shape, supports the first lens group  10 , and comprises a first protrusion  21  that protrudes to the outside of the first zoom ring  20 . The first lens group  10  is coupled to a front of the first zoom ring  20  using a lens support portion  11  disposed therebetween. The first zoom ring  20  moves forward or backward in the axial direction, and thus a position of the first lens group  10  with respect to the axial direction can be adjusted. 
         [0036]    The guide ring  30  has a hollow cylindrical shape and is disposed outside the first zoom ring  20 . An inner wall surface of the guide ring  30  comprises a first guide slot  31  that rectilinearly extends in the axial direction, through which the first protrusion  21  of the first zoom ring  20  passes, and a second guide slot  32  that is inclined in the axial direction and extends in the circumferential direction. The first guide slot  31  guides a movement of the first protrusion  21  to cause the first zoom ring  20  to perform a rectilinear motion in the axial direction. 
         [0037]    A rectilinear guide protrusion  35  that protrudes to the outside of the guide ring  30  is screwed to a rectilinear groove portion  85  that rectilinearly extends in the inner wall surface of the external cylinder  80  in the axial direction. Thus, although the guide ring  30  is disposed in the second cylinder  70 , the guide ring  30  does not rotate with respect to the external cylinder  80  and rectilinearly moves in the axial direction, together with the second cylinder  70 , when the second cylinder  70  rotates with respect to the external cylinder  80 . 
         [0038]    The first cylinder  60  is disposed in the guide ring  30 . The first cylinder  60  has a hollow cylindrical shape, comprises a second protrusion  61  that protrudes to the outside of the first cylinder  60 , and moves in the axial direction while rotating. The second protrusion  61  of the first cylinder  60  is inserted into the second guide slot  32  of the guide ring  30  so that the guide ring  30  can movably support the first cylinder  60 . 
         [0039]    An exterior diameter of the first cylinder  60  is smaller than an interior diameter of the first zoom ring  20 . Thus, when the first zoom ring  20  and the first cylinder  60  are guided by the guide ring  30  and move in the axial direction, the first cylinder  60  can be inserted into the first zoom ring  20 . 
         [0040]    The second zoom ring  50  is movably disposed in the first cylinder  60 . The second zoom ring  50  supports the second lens group  40 . The second lens group  40  is coupled to the second zoom ring  50  using a lens support portion  41  disposed therebetween. 
         [0041]    The second zoom ring  50  comprises a third protrusion  51  that protrudes to the outside of the second zoom ring  50 . The third protrusion  51  of the second zoom ring  50  is inserted into a second zoom ring guide groove  62  formed in an inner wall surface of the first cylinder  60 , and thus the rotation of the first cylinder  60  causes the third protrusion  51  to be guided by the second zoom ring guide groove  62 , and the second zoom ring  50  to rectilinearly move in the axial direction. 
         [0042]    A cutting portion  52  that extends in the axial direction is formed in an exterior wall surface of the second zoom ring  50  in order to prevent the second zoom ring  50  from rotating, and to rectilinearly move in the axial direction. A guide portion  55  that is coupled to the cutting portion  52  and guides a motion of the second zoom ring  50  in the axial direction is disposed between the second zoom ring  50  and the first cylinder  60 . The guide portion  55  is screwed to a guide portion guide groove  64  that extends in the inner wall surface of the first cylinder  60  in the circumferential direction, and thus the first cylinder  60  rotates while the guide portion  55  guides the cutting portion  52 . The guide portion  55  is coupled to the cutting portion  52 , thereby fixing a position of the second zoom ring  50  in the circumferential direction of the guide portion  55 . 
         [0043]    As described above, because the rotation of the first cylinder  60  causes the second zoom ring  50  to move in the first cylinder  60  in the axial direction, which changes a relative position of the second lens group  40  in the axial direction with respect to the first lens group  10 , the zooming function is realized. 
         [0044]    Although the cutting portion  52  and the guide portion  55  are used to guide the second zoom ring  50  to rectilinearly move in the axial direction without rotating during the rotation of the first cylinder  60  in the present embodiment, the invention is not limited thereto. For example,  FIG. 7  is an exploded perspective view of a zoom lens barrel, according to another embodiment. In  FIG. 7 , a pin  155  extending in the axial direction and a guide slot  152  extending in the second zoom ring  150  in the axial direction, through which the pin  155  is inserted, may be used to guide the second zoom ring  150  to rectilinearly move in the axial direction during the rotation of the first cylinder  60 . 
         [0045]    The second cylinder  70  is rotatably disposed around the guide ring  30 . The second cylinder  70  has a hollow cylindrical shape and comprises a fourth protrusion  71  that protrudes to the outside of the second cylinder  70 . An inner wall surface of the second cylinder  70  comprises a first groove portion  72  to which the first protrusion  21  passing through the first guide slot  31  of the guide ring  30  is screwed, and a second groove portion  73  to which the second protrusion  61  passing through the second guide slot  32  of the guide ring  30  is screwed. Thus, the second cylinder  70  movably supports the first zoom ring  20  and the first cylinder  60  and guides a movement of the first zoom ring  20  and the first cylinder  60 . 
         [0046]    The first groove portion  72  comprises a first inclination portion  72   a  that is inclined from a boundary  78  of one end of the second cylinder  70  to a boundary  79  of another end thereof and extends in the circumferential direction, and a second inclination portion  72   b  that is inclined from an end portion of the first inclination portion  72   a  to the boundary  78  and extends in the circumferential direction. 
         [0047]    The first inclination portion  72   a  performs a function of moving the first zoom ring  20  forward in the axial direction with respect to the second cylinder  70 . The second inclination portion  72   b  performs a function of moving the first zoom ring  20  backward in the axial direction with respect to the second cylinder  70 . 
         [0048]    A third groove portion  82  is formed in an inner wall surface of the external cylinder  80 . The second cylinder  70  is disposed in the external cylinder  80 , and the fourth protrusion  71  of the second cylinder  70  is screwed to the third groove portion  82 , so that the external cylinder  80  rotatably supports the second cylinder  70 . Because the fourth protrusion  71  is guided by the third groove portion  82  of the external cylinder  80 , rotation of the second cylinder  70  causes the second cylinder  70  to move in the axial direction. 
         [0049]    A gear  75  that extends in the circumferential direction is installed on an exterior wall surface of the second cylinder  70 . The driving portion  5  of  FIG. 1  is connected to the gear  75 , and thus a driving force generated by the driving portion  5  is transferred to the gear  75 , and the second cylinder  70  rotates with respect to the external cylinder  80 . 
         [0050]    The base  90  is coupled to an end portion of the external cylinder  80 . An optical device  91  that converts image light transmitted through the first lens group  10  and the second lens group  40  into an electrical signal is disposed in the base  90 . The optical device  91  is disposed at a position corresponding to the first lens group  10  and the second lens group  40 . 
         [0051]    A third lens group  100  is disposed between the optical device  91  and the second lens group  40 . The third lens group  100  can move in the axial direction so as to realize a focusing function. 
         [0052]    The third lens group  100  is supported by a third zoom ring  110 . The focus driving unit  7  is coupled to the third zoom ring  110 . The third zoom ring  110  can move in the axial direction by a driving force generated by the focus driving unit  7 , and thus a position of the third lens group  100  in the axial direction can be adjusted. 
         [0053]    The second guide slot  32  comprises a sustaining portion  32   a  that extends in the circumferential direction parallel to a boundary  38  of one end of the guide ring  30 , and a changing portion  32   b  that is inclined from an end portion of the sustaining portion  32   a  to a boundary  39  of another end of the guide ring  30  and extends in the circumferential direction. 
         [0054]    The sustaining portion  32   a  performs a function of sustaining a position of the first cylinder  60  in the axial direction with respect to the guide ring  30  during an initial predetermined section in which the second cylinder  70  starts rotating. The changing portion  32   b  performs a function of changing the position of the first cylinder  60  in the axial direction with respect to the guide ring  30 . 
         [0055]    The second zoom ring guide groove  62  formed in the inner wall surface of the first cylinder  60  comprises a rectilinear portion  62   a  that rectilinearly extends in the axial direction from a boundary  68  of one end of the first cylinder  60  toward a boundary  69  of another end thereof, a backward inclination portion  62   b  that is inclined from an end portion of the rectilinear portion  62   a  toward the boundary  68  of the one end of the first cylinder  60  and extends in the circumferential direction, and a forward inclination portion  62   c  that is inclined from the backward inclination portion  62   b  toward the boundary  69  of the other end of the first cylinder  60  and extends in the circumferential direction. 
         [0056]    The rectilinear portion  62   a  performs a function of moving the second zoom ring  50  forward in the axial direction with respect to the first cylinder  60 . The backward inclination portion  62   b  performs a function of moving the second zoom ring  50  backward in the axial direction with respect to the first cylinder  60 . The forward inclination portion  62   c  performs a function of moving the second zoom ring  50  forward in the axial direction with respect to the first cylinder  60 . 
         [0057]      FIG. 4  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 1 , according to an embodiment of the invention.  FIG. 5  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 4  that is adjusted at a wide-angle lens and performs zooming, according to an embodiment of the invention.  FIG. 6  is a cross-sectional view of the zoom lens barrel assembly of  FIG. 4  that is adjusted at a telephoto-angle lens and performs zooming, according to an embodiment of the invention. 
         [0058]    When the zoom lens barrel assembly is accommodated in a camera or other optical device, all of the second cylinder  70 , the first cylinder  60 , and the first zoom ring  20  are accommodated in the external cylinder  80 . The zoom lens barrel assembly adopts a 2-step barrel structure in which the second cylinder  70  and the first zoom ring  20  protrude in the axial direction with respect to the external cylinder  80 , and thus having a small thickness or short length when the zoom lens barrel assembly is accommodated in an optical device such as a camera, while implementing a high-magnification zooming function. 
         [0059]    If the driving portion  5  operates and generates a driving force, the second cylinder  70  rotates with respect to the external cylinder  80 . The rotational force of the second cylinder  70  is transferred to the first protrusion  21  of the first zoom ring  20  screwed to the first groove portion  72  and to the second protrusion  61  of the first cylinder  60  screwed to the second groove portion  73 . 
         [0060]    The guide ring  30  does not rotate with respect to the external cylinder  80  and rectilinearly moves in the axial direction, together with the second cylinder  70 , when the second cylinder  70  rotates with respect to the external cylinder  80 . Therefore, the first zoom ring  20  can rectilinearly move in the axial direction according to the first protrusion  21  passing through the first guide slot  31  of the guide ring  30 . The first cylinder  60  can rotate with respect to the guide ring  30  and move in the axial direction according to the second protrusion  61  passing through the second guide slot  32  of the guide ring  30 . 
         [0061]    Relative positions of the first lens group  10  and the second lens group  40  are changed owing to the rotation of the second cylinder  70 , and thus the zoom lens barrel assembly can be adjusted at a wide-angle lens as shown in  FIG. 5  or at a telephoto-angle lens as shown in  FIG. 6 . 
         [0062]    The embodiments described herein may comprise a memory for storing program data, a processor for executing the program data, a permanent storage such as a disk drive, a communications port for handling communications with external devices, and user interface devices, including a display, keys, etc. When software modules are involved, these software modules may be stored as program instructions or computer-readable codes, which are executable by the processor, on a non-transitory or tangible computer-readable media such as read-only memory (ROM), random-access memory (RAM), a compact disc (CD), a digital versatile disc (DVD), magnetic tapes, floppy disks, optical data storage devices, an electronic storage media (e.g., an integrated circuit (IC), an electronically erasable programmable read-only memory (EEPROM), and/or a flash memory), a quantum storage device, a cache, and/or any other storage media in which information may be stored for any duration (e.g., for extended time periods, permanently, brief instances, for temporarily buffering, and/or for caching of the information). The computer-readable recording medium can also be distributed over network-coupled computer systems (e.g., a network-attached storage device, a server-based storage device, and/or a shared network storage device) so that the computer-readable code may be stored and executed in a distributed fashion. This media can be read by the computer, stored in the memory, and executed by the processor. As used herein, a computer-readable storage medium excludes any computer-readable media on which signals may be propagated. However, a computer-readable storage medium may include internal signal traces and/or internal signal paths carrying electrical signals therein 
         [0063]    Any references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0064]    For the purposes of promoting an understanding of the principles of the invention, reference has been made to the embodiments illustrated in the drawings, and specific language has been used to describe these embodiments. However, no limitation of the scope of the invention is intended by this specific language, and the invention should be construed to encompass all embodiments that would normally occur to one of ordinary skill in the art. 
         [0065]    The invention may be described in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions. For example, the invention may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements, look-up tables, and the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, where the elements of the invention are implemented using software programming or software elements the invention may be implemented with any programming or scripting language such as C, C++, Java, assembler, or the like, with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Functional aspects may be implemented in algorithms that execute on one or more processors. Furthermore, the invention could employ any number of conventional techniques for electronics configuration, signal processing and/or control, data processing and the like. The words “mechanism” and “element” are used broadly and are not limited to mechanical or physical embodiments, but can include software routines in conjunction with processors, etc. 
         [0066]    The particular implementations shown and described herein are illustrative examples of the invention and are not intended to otherwise limit the scope of the invention in any way. For the sake of brevity, conventional electronics, control systems, software development and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail. Furthermore, the connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device. Moreover, no item or component is essential to the practice of the invention unless the element is specifically described as “essential” or “critical”. 
         [0067]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural. Furthermore, recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Finally, the steps of all methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as” or “for example”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. Numerous modifications and adaptations will be readily apparent to those skilled in this art without departing from the spirit and scope of the invention. 
         [0068]    According to the embodiments of the invention, 5-magnification optical zooming can be implemented using a 2-step zoom lens barrel assembly that unfolds a first zoom ring and a second cylinder in 2 steps, and thus the 2-step zoom lens barrel assembly has a reduced number of parts. Further, the number of relatively moving barrels is reduced, and thus a zoom lens barrel assembly having a small thickness or short length is realized when the zoom lens barrel assembly is accommodated in an optical device such as a camera. 
         [0069]    While various embodiments of the invention have been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims.