Abstract:
A mobile communication terminal comprising a first unit comprising a circuit; a second unit comprising a rotating camera module; and a flexible printed circuit board connecting said circuit to said rotating camera module. The rotating camera module comprising a first peg forming a first turning point for said flexible circuit board to wind around in a first direction, wherein a wound path of said flexible circuit board around said first turning point virtually divides said flexible circuit board into a first region and a second region, said first region being defined by a first portion of said flexible circuit board extending from a connection point to said rotating camera module to said first peg, said second region being defined by a second portion of said flexible circuit board extending from said first peg to an area above said connection point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2005-0063824, filed on Jul. 14, 2005, the content of which is hereby incorporated by reference herein in its entirety. 
   FIELD OF THE INVENTION 
   The present invention relates to a mobile telecommunication handset, and more particularly to a system and method for positioning a flexible printed circuit board in a mobile telecommunication handset. 
   BACKGROUND 
   A mobile telecommunication handset (hereinafter referred to as a mobile handset), which provides wireless voice and data communication on the move, traditionally provides a multimedia application where the subscriber may watch an audio or a video presentation and may click an input device to direct the presentation. Also, mobile handsets with a built-in camera are popular for use in photographing an object or recording video media and storing or transmitting the captured media as electronic information. The camera in the mobile handset is sometimes rotatable to allow a user to point the camera lens at the object to capture an image. The captured image is traditionally sent through a flexible printed circuit board (FPCB) from the built-in camera to a main circuit of the mobile handset. 
   As the length of the FPCB gets shorter, the radio frequency reception gets poorer and a rotation angle of the camera gets smaller, which makes it difficult to focus the object through the display of the mobile handset. A long FPCB is necessary to remedy these problems, which provides more than 5 dB signal-to-noise ratio, compared to a short FPCB. 
   One method of using a long FPCB is to wind the FPCB in one direction twice along the outside surface of a protruding longitudinal opening formed on a cap. This increases noise level, unfortunately. Methods and systems are needed to overcome this shortcoming. 
   SUMMARY 
   In accordance with one aspect of the invention, a camera module in a mobile telecommunication handset is provided. The camera module comprises a camera; a circuit; and a flexible printed circuit board connecting said camera to said circuit. The flexible printed circuit board comprises a first region and a second region. The first and second regions are positioned such that a direction of current flowing over said first region is opposite to a direction of current flowing over said second region to form a virtual grounding between the first region and the second region. Different sections of said flexible printed circuit board are wound in opposite directions to create a plurality of virtual groundings. 
   The camera module may further comprise a rotating element, wherein said flexible printed circuit board is wound on said rotating element to maintain said virtual grounding. The flexible printed circuit board wraps around said rotating element as said rotating element rotates. Direction of current flowing over an outside section of said flexible printed circuit board is opposite to a direction of current flowing over an inside section of said flexible printed circuit board, creating an additional virtual grounding. 
   The rotating element further comprises a protruding hook to prevent said rotating element from rotating beyond a certain position. In one embodiment, the rotating element further comprises a groove creating added traction to a surface of said rotating element to allow a user rotate said rotating element. Preferably, the rotating element is attached to the camera to allow the camera to rotate. In another embodiment, the rotating element further comprises a peg around which said flexible printed circuit board is wound, and an indicator showing a preferred path around said peg for said flexible printed circuit board. The indicator may comprise a groove, such that the flexible printed circuit board is positioned in said groove. 
   In accordance with another aspect of the invention, a camera module provided in a mobile telecommunication handset, comprises a rotation-enabled camera housing; a camera attached to said rotation-enabled camera housing; a circuit; a connection line connecting said circuit to said camera; and a cap attached to said rotation-enabled camera housing, wherein said connection line is wound around said cap. The cap comprises a first peg, wherein said connection line is wound around said first peg in a first direction. The cap may further comprise a second peg, wherein said connection line is wound around said second peg in a second direction, Preferably, the connection line is wound clockwise around said first peg, and said connection line is wound counterclockwise around said second peg, for example. 
   In accordance with yet another aspect of the invention, a mobile communication terminal comprises a first unit comprising a circuit; a second unit comprising a rotating camera module; and a flexible printed circuit board connecting said circuit to said rotating camera module. The rotating camera module comprises a first peg forming a first turning point for said flexible circuit board to wind around in a first direction, wherein a wound path of said flexible circuit board around said first turning point virtually divides said flexible circuit board into a first region and a second region. 
   The first region is defined by a first portion of said flexible circuit board extending from a connection point to said rotating camera module to said first peg. The second region is defined by a second portion of said flexible circuit board extending from said first peg to an area above said connection point, wherein a direction of a current in said first region is opposite a direction of a current in said second region, creating a first virtual grounding. 
   In one embodiment, the rotating camera module may further comprise a second peg forming a second turning point for said flexible circuit board to wind around in a second direction, wherein said wound path of said flexible circuit board around said second turning point virtually divides said flexible circuit board into a third region and a fourth region. The third region is defined by a third portion of flexible circuit board extending from a said area above said connection point to said second peg. The fourth region is defined by a fourth portion of flexible circuit board extending from said second peg to said first unit, wherein a direction of a current in said third region is opposite a direction of a current in said fourth region, creating a second virtual grounding. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a perspective view of a mobile telecommunication handset having a rotation-enabled camera according to one embodiment. 
       FIG. 2  is an exploded view of the rotation-enabled camera of  FIG. 1 , in accordance with one embodiment. 
       FIG. 3  is a view showing an embodiment in which the FPCB is positioned in the mobile telecommunication handset according to one embodiment. 
       FIG. 4  is a schematic view showing how the FPCB is wound in accordance with one embodiment. 
       FIG. 5  is a flow diagram for a method of positioning a FPCB in a mobile telecommunication handset, in accordance with one embodiment, 
   

   Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a mobile telecommunication handset in accordance with the present invention comprises a first body  10  capable of visual telecommunication, a second body  20  rotatably coupled to first body  10 , and a camera  30  with a converging lens  31 , rotatably provided on first body  10  in a manner to focus lens  31  towards an object. 
   First body  10  comprises a first body housing  11  enclosing a circuit performing functions for telecommunication and a rechargeable battery  12  detachably provided on a back side of housing  11 . 
   Second body  20  comprises a second body housing  21  for housing a main liquid crystal display (not shown) and an auxiliary liquid crystal display  22  provided on a front center side of second body housing  21 . An opening  23  is provided on the front lower side of second body housing  21  to propagate a sound wave from a speaker provided inside first body housing  11 . 
   Referring to  FIG. 2 , camera  30  comprises a converging lens  31  causing incident light rays initially parallel to a central axis to converge, a camera module  32  which senses and processes light intensities across a plane of focus of camera lens  31 , an FPCB  33  through which a signal from a camera module may be transmitted to a circuit (not shown), a rotation-enabled camera housing  34 , and a cap  36 . 
   Cap  36  closes opening  34   d  of rotation-enabled camera housing  34  after camera module  32  is inserted into rotation-enabled camera housing  34 . A camera housing support  35  on which a rotation axis opening  35   a  is formed is provided to support the rotation of rotation-enabled camera housing  34 . As shown, rotation disk  34   c  is formed on one side of cap  36  through opening  34   d  of rotation-enabled camera housing  34 . 
   The converging lens  31  causes incident light rays initially parallel to a central axis to converge. A lens frame  32   a  is formed to enclose converging lens  31 , and a pair of protruding regions  32   b  are formed on both lateral sides of lens frame  32   a  to fix camera module  32  inside rotation-enabled camera housing  34 . 
   Rotation-enabled camera  30  can be rotated at an angle of 120 degrees, for example, so that converging lens  31  may be accordingly pointed towards an object and viewed through a main liquid crystal display (not shown) on a mobile telecommunication handset. FPCB  33 , which is durable and relatively long to prevent tension, is wound, preferably at least twice, around an outside surface of a protruding longitudinal bend  36   b  formed on the cap  36 . 
   One end of FPCB  33  is connected to one side of camera module  32  and other end  33   a  is connected to a circuit (not shown) of the mobile telecommunication handset. Accordingly, FPCB  33  serves as a conduit along which current and information flows from a circuit of the mobile telecommunication handset (not shown) to camera module  32 . 
   Evenly spaced horizontal grooves  34   a  are formed on an outside surface of the rotation-enabled camera housing  34 , creating added traction to help a user rotate the rotation-enabled camera housing. The rotation-enabled camera housing  34  has an inner cylindrical space with opening  34   d  on a lateral side, into which camera module  32  is inserted. An opening  34   b  for converging lens  31  is formed on an outside surface of tie rotation-enabled camera housing  34 . 
   Rotation-enabled camera housing support  35  comprises a rotation axis opening  35   a  into which rotation disk  34   c  of rotation-enabled camera housing  36  is inserted. A protruding region  35   b  is formed on an inside surface of rotation axis opening  35   a  to limit a rotation angle of rotation-enabled camera housing  34 . In one embodiment, a position guide region  35   c  is formed to couple camera  30  to the first body  10 . 
   Cap  36  comprises a rotation disk  34   c , outside surface  36   a  for a protruding longitudinal opening  36   b . Cap  36  has a first peg  37   a  and a second peg  37   b  around which FPCB  33  turns. That is, the first and second pegs  37   a  and  37   b  upon which FPCB  33  wraps around, or a groove covering both sides of FPCB  33  to minimize electromagnetic interference (EMI) and noise, may be formed on a surface of a lateral side of the rotation disk  34   c.    
   Referring to  FIGS. 2 ,  3  and  4 , one end of FPCB  33  is fixed to camera module  32  and is inserted into rotation-enabled camera housing  34 . Preferably, the FPCB  33  is placed in cap  36  such that it protrudes from protruding longitudinal opening  36   b , as shown. FPCB  33  protrudes from protruding longitudinal opening  36   b  and is wound around second peg  37   b  in a preferably counterclockwise direction. Thereafter, FPCB  33  is wound around first peg  37   a  in preferably a clockwise direction. In one embodiment, another end of FPCB  33  is wound, for example, two times along outside surface  36   a  of protruding longitudinal opening  36   b  before it is connected to a circuit (not shown) in first body  10 . 
   FPCB  33  is preferably divided into three regions depending on the winding direction: a first winding region  52 , a second winding region  54 , and a non-winding region  57 . First winding region  52  is formed when FPCB  33  is wound (e.g., counterclockwise) around second peg  37   b  positioned near protruding longitudinal opening  36   b . Second winding region  54  is formed when FPCB  33  is wound (e.g., clockwise) around second peg  37   a  positioned near protruding longitudinal opening  36   b . As such, FPCB  33  follows a preferred winding path, starting from protruding longitudinal opening  36   b  and ending at connector  56 , around cap  36 . In an exemplary embodiment, cap  36  may comprise a groove within which FPCB  33  follows. 
     FIG. 4  is a schematic view showing how the FPCB is wound in accordance with one embodiment. In the first winding region  52 , direction of current flowing over a first signal line L 1  is opposite to that of current flowing over a second line L 2 . As a result, a potential difference is zero between first and second lines L 1  and L 2 , thus forming a first virtual grounding  51 . 
   In the second winding region  54 , direction of current flowing over a third signal line L 3  is opposite to that of current flowing over a fourth line L 4  corresponding to a point where first winding region  52  transitions to second winding region  54 . As a result, the potential difference is zero between third and fourth lines L 3  and L 4 , thus forming a second virtual grounding  53 . 
   In one embodiment, non-winding region  57  is a continuation of second winding region  54 , which in turn is a continuation of first winding region  52 . Non-winding region  57 , preferably, is in approximately a straight line along a camera housing support  35 . A connector  56  is provided on an end of non-winding region  57 , which is connected to the circuit (not shown). In non-winding region  57 , a direction of current flowing over a fifth signal line L 5  is opposite to that of current flowing over a sixth line L 6 . As a result, potential difference is zero between the fifth and sixth lines L 5  and L 6 , forming a third virtual grounding  55 . 
   Accordingly, the direction of current on outside section of FPCB  33  is opposite to a direction of current flowing over an inside section of FPCB  33 . Preferably, the direction of current from L 5  to camera housing support  35 , in one embodiment, runs towards camera housing support  35 , while the direction of current from L 2  runs towards L 6 . Thus, as cap  36  rotates counterclockwise and FPCB wraps around cap  36  even more, third virtual grounding  55  expands in length, further decreasing potential noise. In a certain embodiment, protruding region  35   b  prevents non-winding region  57  from wrapping around cap  36  past first peg  37   a  so as to prevent directions of current from enhancing each other. 
   First winding region  52  is formed as a result of winding FPCB  33  in a first direction (e.g., counterclockwise) and second region  54  is formed as a result of winding FPCB  33  in a second direction (e.g., clockwise). Signal lines L 2 , L 4 , and L 5  and signal lines L 1 , L 3 , and L 5  are symmetrical with respect to the first, second, and third virtual groundings  51 ,  53  and,  54 , respectively. The direction of current flowing on signal lines L 2 , L 4 , and L 6  are opposite to that of current flowing on signal lines L 1 , L 3 , and L 5 , thus resulting in their respective potential differences being offset and the directions of the magnetic fields being the same. This is known as the odd mode. 
   Thus, in one embodiment, FPCB  33  is arranged in such a manner that a direction of current flowing over one signal line is opposite to that of current flowing over an opposite signal line in first and second winding region  52  and  54 , and non-winding region  57 , This results in a potential difference in the two regions and causes the respective magnetic fields to cancel each other. 
   One end of FPCB  33  is connected to camera module  32 . Another end of FPCB  33  protrudes from protruding longitudinal opening  36   b  and is wound in a manner to decrease noise. That is, FPCB  33  is wound in such a manner that first, second, and third virtual grounding  51 ,  53 , and  55  are formed around the protruding longitudinal opening  36   b.    
   This arrangement of FPCB  33  in a mobile telecommunication device makes it possible for a user to point camera tens  31  towards the user by rotating horizontal grooves  34   a  of rotation-enabled camera housing  34  with, for example, the user&#39;s finger towards an outside of second body  20  or towards an inside of second body  20  after swinging second body  20  open to make or receive a call. This allows user&#39;s image to be shown on the display of another party&#39;s mobile telecommunication handset over an air interface. 
   Thus, FPCB  33  with a relatively long length can be connected to camera module  32  to allow a user to freely point camera lens  31  towards an outside or an inside of a mobile telecommunication handset by rotating rotation-enabled camera housing  34 . 
   Referring to  FIGS. 4 and 5 , a preferred method for positioning an FPCB is now described in detail FPCB  33  starts from a protruding longitudinal opening  36   b , wraps around a second peg  37   b  and forms an oval-shaped first winding unit  52 , such that a first winding region in oval shape is formed on one lateral side of cap  36  by the winding FPCB  33  (S 10 ). This is known as an odd mode where a direction of current flowing over a left signal line L 1  is opposite to a direction of current flowing over a right signal line L 2 . A first virtual grounding  51  is formed by potential difference between left and right signal lines L 1  and L 2 . 
   FPCB  33  then wraps around a first peg  37   a  and forms a second winding region  54  on the other lateral side of cap  36 , by winding FPCB  33  continuously from the first winding region  52 , which is preferably oval-shaped (S 20 ). This is also known as an odd mode where a direction of current flowing over a left signal line L 3  is opposite to a direction of current flowing over a right signal line L 4 . A second virtual grounding  53  is formed by a potential difference between the left and right signal lines L 3  and L 4 . 
   FPCB  33  then forms a non-winding region  57  by making the second winding region  54  close to the outside of the first winding region  52 , which preferably extends along camera housing support  35  (S 30 ). A connector  56  provided on an end of non-winding region  57  is connected to a circuit of a first body  10 . A direction of current flowing over a fifth signal line L 5  in non-winding region  57  is opposite to a direction of current flowing over a sixth signal line L 6  in first winding region  52 . Thus, a third virtual grounding  55  is formed by a potential difference halfway between fifth and sixth signal lines L 5  and L 6 . 
   FPCB  33  is preferably long enough to connect camera module  32  to the circuit (not shown), for example, after forming first and second winding regions  52  and  54  without creating much noise. This makes it possible to rotate rotation-enabled camera housing  30  to freely point camera lens  31  to an outside or an inside of a mobile telecommunication handset when making or receiving a call. FPCB  33  is arranged in such a manner that a direction of current flowing over one signal line is opposite to a direction of current flowing over an opposite signal line in first and second winding regions  52  and  54 , and non-winding region  57 , thereby forming first, second, and third virtual groundings  51 ,  53 , and  55 . As a result, the directions of the magnetic fields are the same. This makes it possible to reduce noise in visual telecommunication. 
   As described above, FPCB  33 , when provided on one rotation-enabled camera, can be arranged to have first and second winding regions  52  and  54  and non-winding region  57 , depending on the length of the FPCB. This makes it possible to reduce noise and improve image quality. Furthermore, this design prevents noise, such as electromagnetic waves, from being introduced into the main antenna. This leads to an improvement of up to 3 dB in the signal-to-noise ratio over a mobile telecommunication handset with a conventional camera, which uses visual telecommunication. 
   Also, this design makes it possible to adjust the length of FPCB  33  connected to camera module  32  to obtain the same sensitivity, as well as prevent a breakage of FPCB  33  due to frequent bending. The wider rotation angle of the camera helps increase transmission and reception sensitivity of the antenna. 
   As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.