referring to fig2 in accordance with one aspect of the invention , a folder type rotating - keypad mobile handset comprises a main body 100 and a cover 200 one end of which is pivotally connected by a hinge mechanism 300 . a microphone 130 is disposed at a lower portion of the main body 100 and a navigation keypad 120 for a function manipulation is disposed at a front upper portion . a disc type rotating - keypad 110 is rotatably mounted between the microphone 130 and the navigation keypad 120 , for example . a speakerphone 230 is disposed at an inner upper portion of the cover 200 , and a longitudinally oriented display screen 210 is installed at a lower side of the speaker phone 230 . in the portrait image mode , the rotating - keypad 110 is arranged in a first direction so that information displayed on the display screen 210 has an orientation that is compatible with the orientation of the rotating - keypad 110 . [ 0035 ] fig3 is a drawing illustrating the rotating - keypad mobile handset repositioned into a landscape image mode . with reference to fig3 the rotating - keypad 110 is rotated at an angle of approximately 90 ° in the clockwise direction from a portrait image mode to match the display orientation of an image displayed on the display screen 210 has been rotated at the angle of approximately 90 ° in the clockwise direction . in such a case , the up , down , left , and right direction keys 121 , 122 , 123 and 124 of the navigation keypad 120 respectively become left , right , down , and up direction keys in relation to the new orientation of the image . [ 0038 ] fig4 is a side view of the folder type rotating - keypad mobile handset of fig3 . as shown in fig4 the main body 100 comprises a base for mounting the keypad into a mounting bay 150 that is recessed into the face of the mobile terminal correspondingly to the rotating - keypad 110 , so that the rotating - keypad 110 is rotatably mounted in the mounting bay 150 . the mounting bay 150 is provided with a pair of openings 160 formed on two opposite sides of the wall formed around the mounting bay 150 such that the circumferential surface of the rotating - keypad 110 is partially exposed through the openings 160 . this allows a user to rotate the rotating - keypad 110 by manipulating the exposed portions of the rotating - keypad 110 . [ 0041 ] fig5 a and fig5 b are perspective planar and a side views illustrating the rotating - keypad 110 of the mobile handset of fig2 . as shown in fig5 a and fig5 b , in one embodiment , the rotating - keypad 110 comprises a disc - shaped keypad body , a rotation shaft 113 approximately perpendicularly connected at a center of the bottom surface of keypad body , and a preferably disc - shaped anchor 115 downwardly protruding from the bottom surface of keypad body around the rotation shaft 113 , the anchor 115 preferably having smaller diameter than that of the keypad body 110 . it should be noted that the keypad body and anchor 115 may be shaped in other geometric configurations . in one embodiment , the keypad body 110 is provided with a circumferential ridged surface 111 so as to facilitate a better grip for a user to rotate the rotating - keypad 110 by applying pressure on the ridged surface exposed through the openings 160 . the anchor 115 of the rotating - keypad includes a stopper 117 formed at one side of the circumferential surface of the anchor 115 , and a first contact portion 119 formed on the bottom surface for electrical connection with the main body 100 of the mobile handset . in some embodiments , the anchor 115 is provided with first and second fixing holes 112 a and 112 b formed on the circumferential surface thereof at respective angles of approximately 90 ° and 180 ° relative to the position of the stopper 117 in a counterclockwise direction , for example . the rotating - keypad 110 , may rotate in either clockwise or counter - clockwise directions , depending on design and implementation . [ 0046 ] fig6 is a top planar view showing a keypad - mounting bay 150 of the rotating - keypad mobile handset of the present invention , in accordance with one embodiment . as shown in fig6 the mounting bay 150 is provided with a shaft hole 153 centrally formed for receiving the rotation shaft 113 of the rotating - keypad 110 . a preferably concaved portion 155 is formed on the surface of the mounting bay 150 for receiving the anchor 115 of the rotating - keypad around the shaft hole 153 . alternatively , concaved portion 155 may be a cavity formed in any shape suitable for housing that anchor 115 . the concave portion 155 is provided with a second contact portion 156 a formed on the bottom surface thereof so as to contact the first contact portion 119 in the portrait image mode and a third contact portion 156 b formed at an approximate angle of 90 ° in the clockwise direction , for example , from the second contact portion 156 a . the third contact portion 156 b contacts first contact portion 119 in the landscape image mode . also , the concave portion 155 is provided with a guide groove 158 formed along the circumferential wall thereof as much as 90 ° on the axis of the shaft hole 113 between the second and third contact portions 156 a and 156 b for receiving the stopper 117 of the rotating - keypad 110 such that the stopper 117 slides along the guide groove 158 to limit rotation of the rotating - keypad at the angle of 90 °. the keypad - mounting bay 150 is provided with a holder passage 157 communicating outside the main body 100 through which a keypad holder 159 is inserted so as to be manipulated outside . the keypad holder 159 is downwardly biased by an elastic member ( not shown ) so that a head 159 a of the keypad holder 159 is engaged with the first and second fixing holes 112 a or 112 b through the holder fixing hole 157 a . when the rotating - keypad 110 is mounted in the keypad mounting bay 150 , the first contact portion 119 of the rotating - keypad 110 contacts the second contact portion of the keypad mounting bay 150 and the stopper 117 of the rotating - keypad 110 is positioned in the guide groove 158 of the keypad mounting bay 150 . the head 159 a of the holder 159 is inserted into the first fixing hole 112 a of the anchor 115 mounted inside the concave portion 155 by the elastic member . the operation of the rotating - keypad mobile handset constructed as above will now be explained . with reference to fig2 in a state that the rotating - keypad mobile handset of the present invention is set in a portrait image mode , the display screen 210 displays information in a vertical orientation in relation to the body of the mobile handset . when a program requiring a landscape image mode is executed by a key manipulation on the rotating - keypad 110 in the portrait image mode , the display screen 210 displays information rotated at the approximate angle of 90 ° in a clockwise direction , for example . referring to fig6 in such a case , a user pushes up a knob 159 b of the holder 159 , for example , away from the main body , and rotates the rotating - keypad 110 in a clockwise direction , for example . at this time , the rotation angle of the rotating - keypad 110 is limited at the angle of , for example , 90 ° by a guide groove 158 , so that the second fixing hole 112 b is positioned facing the fixing hole 157 a . in this state , the holder 159 is biased downwardly by the elastic force of the elastic member , and accordingly , the holder 159 a is engaged with the second fixing hole 112 b through the holder fixing hole 157 a , so that the keypad is completely rotated to be easily manipulated in the landscape image mode . in the landscape image mode , the first contact portion 119 of the rotating - keypad 110 is positioned rotated at the approximate angle of 90 ° with respect to the position of the portrait image mode and is in contact with a third contact portion 156 b of the keypad mounting bay 150 . accordingly , the operation mode of the mobile handset is converted from the portrait image mode to the landscape image mode or vice versa , and the electric connection between the rotating - keypad and the main body is maintained in so that a signal provided by the keypad is transmitted to the main body . in a case that the mobile handset is converted from the landscape image mode to the portrait image mode , the rotating - keypad 110 can be rotated at the approximate angle of 90 ° in the counterclockwise direction and fixed in the same manner as described above . the rotating - keypad 110 can be implemented in such a manner that the rotating - keypad 110 automatically rotates in a required direction in a predetermined time if the display mode is converted from the portrait image mode to the landscape image mode and vice versa . the display mode conversion of the display screen 210 can be performed according to the rotational movement of the rotating - keypad such that the display mode is converted by rotating the rotating - keypad 110 . in some embodiments , the rotating - keypad 110 may also be used as a dial for adjusting brightness of the display screen 210 . [ 0066 ] fig7 is a front view of a rotating - keypad mobile handset in accordance with a second embodiment of the present invention . fig8 is a view showing that the rotating - keypad of the mobile handset of fig7 is rotated in the counterclockwise direction , and fig9 is a side view of the rotating - keypad mobile handset of fig7 . as shown in fig7 a flip type rotating - keypad mobile handset according to the second embodiment of the present invention is similar to the folder type mobile handset in structure and function of elements , except that a display screen 650 , a rotating - keypad 610 , and a navigation keypad 620 are arranged at a main body 600 , and a flip 700 is pivotally attached at a lower end portion of the main body 600 . as described above , the rotating - keypad mobile handset of the present invention can be adaptively applied to utilize the entire screen by displaying information rotated at the approximate angle of 90 ° when a landscape image display is needed . also , in case that a landscape image is displayed on the screen rotated at the approximate angle of 90 °, the rotating - keypad of the mobile handset may be rotated to have the same orientation , so that the user can manipulate the keypad while viewing the information of the landscape image without confusion . moreover , since the up , down , left , and right direction keys on the navigation keypad respectively function to move the image in accordance with the respective direction and orientation , the user can intuitively manipulate the direction keys . 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 of the 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 meets and bounds of the claims , or equivalence of such meets and bounds are therefore intended to be embraced by the appended claims .