Positioning a flexible printed circuit board in a mobile telecommunication terminal

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.

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.

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 toFIG. 1, a mobile telecommunication handset in accordance with the present invention comprises a first body10capable of visual telecommunication, a second body20rotatably coupled to first body10, and a camera30with a converging lens31, rotatably provided on first body10in a manner to focus lens31towards an object.

First body10comprises a first body housing11enclosing a circuit performing functions for telecommunication and a rechargeable battery12detachably provided on a back side of housing11.

Second body20comprises a second body housing21for housing a main liquid crystal display (not shown) and an auxiliary liquid crystal display22provided on a front center side of second body housing21. An opening23is provided on the front lower side of second body housing21to propagate a sound wave from a speaker provided inside first body housing11.

Referring toFIG. 2, camera30comprises a converging lens31causing incident light rays initially parallel to a central axis to converge, a camera module32which senses and processes light intensities across a plane of focus of camera lens31, an FPCB33through which a signal from a camera module may be transmitted to a circuit (not shown), a rotation-enabled camera housing34, and a cap36.

Cap36closes opening34dof rotation-enabled camera housing34after camera module32is inserted into rotation-enabled camera housing34. A camera housing support35on which a rotation axis opening35ais formed is provided to support the rotation of rotation-enabled camera housing34. As shown, rotation disk34cis formed on one side of cap36through opening34dof rotation-enabled camera housing34.

The converging lens31causes incident light rays initially parallel to a central axis to converge. A lens frame32ais formed to enclose converging lens31, and a pair of protruding regions32bare formed on both lateral sides of lens frame32ato fix camera module32inside rotation-enabled camera housing34.

Rotation-enabled camera30can be rotated at an angle of 120 degrees, for example, so that converging lens31may be accordingly pointed towards an object and viewed through a main liquid crystal display (not shown) on a mobile telecommunication handset. FPCB33, which is durable and relatively long to prevent tension, is wound, preferably at least twice, around an outside surface of a protruding longitudinal bend36bformed on the cap36.

One end of FPCB33is connected to one side of camera module32and other end33ais connected to a circuit (not shown) of the mobile telecommunication handset. Accordingly, FPCB33serves as a conduit along which current and information flows from a circuit of the mobile telecommunication handset (not shown) to camera module32.

Evenly spaced horizontal grooves34aare formed on an outside surface of the rotation-enabled camera housing34, creating added traction to help a user rotate the rotation-enabled camera housing. The rotation-enabled camera housing34has an inner cylindrical space with opening34don a lateral side, into which camera module32is inserted. An opening34bfor converging lens31is formed on an outside surface of tie rotation-enabled camera housing34.

Rotation-enabled camera housing support35comprises a rotation axis opening35ainto which rotation disk34cof rotation-enabled camera housing36is inserted. A protruding region35bis formed on an inside surface of rotation axis opening35ato limit a rotation angle of rotation-enabled camera housing34. In one embodiment, a position guide region35cis formed to couple camera30to the first body10.

Cap36comprises a rotation disk34c, outside surface36afor a protruding longitudinal opening36b. Cap36has a first peg37aand a second peg37baround which FPCB33turns. That is, the first and second pegs37aand37bupon which FPCB33wraps around, or a groove covering both sides of FPCB33to minimize electromagnetic interference (EMI) and noise, may be formed on a surface of a lateral side of the rotation disk34c.

Referring toFIGS. 2,3and4, one end of FPCB33is fixed to camera module32and is inserted into rotation-enabled camera housing34. Preferably, the FPCB33is placed in cap36such that it protrudes from protruding longitudinal opening36b, as shown. FPCB33protrudes from protruding longitudinal opening36band is wound around second peg37bin a preferably counterclockwise direction. Thereafter, FPCB33is wound around first peg37ain preferably a clockwise direction. In one embodiment, another end of FPCB33is wound, for example, two times along outside surface36aof protruding longitudinal opening36bbefore it is connected to a circuit (not shown) in first body10.

FPCB33is preferably divided into three regions depending on the winding direction: a first winding region52, a second winding region54, and a non-winding region57. First winding region52is formed when FPCB33is wound (e.g., counterclockwise) around second peg37bpositioned near protruding longitudinal opening36b. Second winding region54is formed when FPCB33is wound (e.g., clockwise) around second peg37apositioned near protruding longitudinal opening36b. As such, FPCB33follows a preferred winding path, starting from protruding longitudinal opening36band ending at connector56, around cap36. In an exemplary embodiment, cap36may comprise a groove within which FPCB33follows.

FIG. 4is a schematic view showing how the FPCB is wound in accordance with one embodiment. In the first winding region52, direction of current flowing over a first signal line L1is opposite to that of current flowing over a second line L2. As a result, a potential difference is zero between first and second lines L1and L2, thus forming a first virtual grounding51.

In the second winding region54, direction of current flowing over a third signal line L3is opposite to that of current flowing over a fourth line L4corresponding to a point where first winding region52transitions to second winding region54. As a result, the potential difference is zero between third and fourth lines L3and L4, thus forming a second virtual grounding53.

In one embodiment, non-winding region57is a continuation of second winding region54, which in turn is a continuation of first winding region52. Non-winding region57, preferably, is in approximately a straight line along a camera housing support35. A connector56is provided on an end of non-winding region57, which is connected to the circuit (not shown). In non-winding region57, a direction of current flowing over a fifth signal line L5is opposite to that of current flowing over a sixth line L6. As a result, potential difference is zero between the fifth and sixth lines L5and L6, forming a third virtual grounding55.

Accordingly, the direction of current on outside section of FPCB33is opposite to a direction of current flowing over an inside section of FPCB33. Preferably, the direction of current from L5to camera housing support35, in one embodiment, runs towards camera housing support35, while the direction of current from L2runs towards L6. Thus, as cap36rotates counterclockwise and FPCB wraps around cap36even more, third virtual grounding55expands in length, further decreasing potential noise. In a certain embodiment, protruding region35bprevents non-winding region57from wrapping around cap36past first peg37aso as to prevent directions of current from enhancing each other.

First winding region52is formed as a result of winding FPCB33in a first direction (e.g., counterclockwise) and second region54is formed as a result of winding FPCB33in a second direction (e.g., clockwise). Signal lines L2, L4, and L5and signal lines L1, L3, and L5are symmetrical with respect to the first, second, and third virtual groundings51,53and,54, respectively. The direction of current flowing on signal lines L2, L4, and L6are opposite to that of current flowing on signal lines L1, L3, and L5, 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, FPCB33is 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 region52and54, and non-winding region57, This results in a potential difference in the two regions and causes the respective magnetic fields to cancel each other.

One end of FPCB33is connected to camera module32. Another end of FPCB33protrudes from protruding longitudinal opening36band is wound in a manner to decrease noise. That is, FPCB33is wound in such a manner that first, second, and third virtual grounding51,53, and55are formed around the protruding longitudinal opening36b.

This arrangement of FPCB33in a mobile telecommunication device makes it possible for a user to point camera tens31towards the user by rotating horizontal grooves34aof rotation-enabled camera housing34with, for example, the user's finger towards an outside of second body20or towards an inside of second body20after swinging second body20open to make or receive a call. This allows user's image to be shown on the display of another party's mobile telecommunication handset over an air interface.

Thus, FPCB33with a relatively long length can be connected to camera module32to allow a user to freely point camera lens31towards an outside or an inside of a mobile telecommunication handset by rotating rotation-enabled camera housing34.

Referring toFIGS. 4 and 5, a preferred method for positioning an FPCB is now described in detail FPCB33starts from a protruding longitudinal opening36b, wraps around a second peg37band forms an oval-shaped first winding unit52, such that a first winding region in oval shape is formed on one lateral side of cap36by the winding FPCB33(S10). This is known as an odd mode where a direction of current flowing over a left signal line L1is opposite to a direction of current flowing over a right signal line L2. A first virtual grounding51is formed by potential difference between left and right signal lines L1and L2.

FPCB33then wraps around a first peg37aand forms a second winding region54on the other lateral side of cap36, by winding FPCB33continuously from the first winding region52, which is preferably oval-shaped (S20). This is also known as an odd mode where a direction of current flowing over a left signal line L3is opposite to a direction of current flowing over a right signal line L4. A second virtual grounding53is formed by a potential difference between the left and right signal lines L3and L4.

FPCB33then forms a non-winding region57by making the second winding region54close to the outside of the first winding region52, which preferably extends along camera housing support35(S30). A connector56provided on an end of non-winding region57is connected to a circuit of a first body10. A direction of current flowing over a fifth signal line L5in non-winding region57is opposite to a direction of current flowing over a sixth signal line L6in first winding region52. Thus, a third virtual grounding55is formed by a potential difference halfway between fifth and sixth signal lines L5and L6.

FPCB33is preferably long enough to connect camera module32to the circuit (not shown), for example, after forming first and second winding regions52and54without creating much noise. This makes it possible to rotate rotation-enabled camera housing30to freely point camera lens31to an outside or an inside of a mobile telecommunication handset when making or receiving a call. FPCB33is 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 regions52and54, and non-winding region57, thereby forming first, second, and third virtual groundings51,53, and55. 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, FPCB33, when provided on one rotation-enabled camera, can be arranged to have first and second winding regions52and54and non-winding region57, 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 FPCB33connected to camera module32to obtain the same sensitivity, as well as prevent a breakage of FPCB33due to frequent bending. The wider rotation angle of the camera helps increase transmission and reception sensitivity of the antenna.