Abstract:
A portable device which incorporates a body unit and a display unit incorporating a display screen formed on the front surface and/or the rear surface. The body unit includes sidewalls formed projecting forwards from the left and right side surfaces of the body unit so as to allow the display unit to rest in a stable fashion. Each sidewall of the body unit has a holding member of which one end is secured to one region of the sidewall. A portion of the holding member is positioned inside the display unit. A movement hole is formed in the side surface of the display unit. A portion of the holding member passes through the movement hole so as to allow the display unit to slide on the main body.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY 
     This patent application claims benefit under 35 U.S.C. 119(e), 120, 121, or 365(c), and is a National Stage entry from International Application No. PCT/KR2011/005585, filed Jul. 29, 2011, which claims priority to Korean Patent Application Nos. 10-2010-0073671 which was filed Jul. 29, 2010, 10-2011-0058510 which was filed Jun. 16, 2011, and 10-2011-0073330 which was filed Jul. 23, 2011, entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     a. The present invention relates to a portable device that can slide/glide or rotate/tilt, and more particularly, to a portable device structure which has a display screen on the front or rear surface of a display unit of a portable device, in which the display unit can be slid, tilted to a predetermined angle or rotated to turn 180 degrees without interruption for use. 
     2. Background Art 
     Various types of portable devices have been proposed in response to the development of telecommunication devices. According to current trends, a variety of functions are added to portable devices for use. That is, a portable device can serve as an MPEG-1 Audio Layer-3 (MP3) player, a digital multimedia broadcasting (DMB) receiver or a personal digital assistant (PDA). In addition, a user can play moving images, enjoy application programs (apps), check email, search for information (on the Internet), edit a document (e.g. using MS Office), and so on. 
     For execution of those functions, a large display screen which can display various sorts of image information and entertainment apps is required. However, a portable device that also has the function of a mobile phone has various types of function buttons on the portion where the display screen is located. This consequently reduces the size of the display screen. 
     In the related art, a portable media player (PMP), a type of the above-described portable devices, has a large screen (e.g. 4.3″, 4.0″ or the like), which consumes more power than a small screen (e.g. 2.2″, 2.0″ or the like). Therefore, for the MP3 player (MP3P) function or the voice speaking function, the PMP unnecessarily uses “the large screen that consumes high power,” which is one factor that reduces the usage time. 
     Therefore, it is required to minimize the battery consumption and increase the usage time by using “a small screen that consumes low power” in the speaking function of a mobile communication terminal or in the MP3P function. Also, regarding the visual or functional aspect of a product, it is required that usability and convenience are provided by using the large screen (e.g. 4.3″, 4.0″ or the like) for some functions, such as PMP, navigation, ultra-mobile personal computer (UMPC), game player, web surfing and email functions, and using the small screen (e.g. 2.2″, 2.0″ or the like) for some functions, such as mobile phone, MP3P and short message service (SMS) functions. 
     In addition, since a user individually purchases various sorts of portable devices, such as an MP3P, a DMB receiver, a PMP, a PDA, a PlayStation portable (PSP), a UMPC, a navigator, a mobile phone and the like, as required, he/she spends too much money. Disposal of respective devices also causes environmental pollution and wastes of resources. 
     SUMMARY 
     The present invention has been made to solve the foregoing problems with the related art, and therefore the present invention is intended to provide a portable device structure which has a small display screen and a large display screen respectively on both surfaces of a display unit which is coupled with a body such that it can slide/glide on or rotate/tilt about the body. The small display screen is used for a voice speaking function, and the large display screen is used for displaying images and playing entertainment apps, so that a variety of functions can be carried out. It is also convenient for a user to view information on the display screens or execute an operation. 
     The present invention is also intended to provide a portable device structure in which various types of portable devices (e.g., an MP3P, a DMB receiver, a PMP, a PDA, a PSP, a UMPC, a navigator, a mobile phone and the like) which exist as separate articles to realize their own functions in the related art are integrated into one terminal such that the functions can be carried out by rotating a display unit into a desirable operation mode. Specifically, the MP3P function, the voice speaking function that is the unique function of the mobile phone, and the like can be carried out using a front display screen, whereas the PSP function, the DMB receiver function, the PMP function of playing a movie stored in a memory, the PDA function of displaying information, the function of the UMPC which is also referred to as a PC in the hand, the navigation function and the like are carried out using a rear display screen. 
     The present invention is also intended to provide a portable device structure in which front and rear display screens are erected when a display unit is raised about a slider such that a user can view information displayed on the front and rear display screens at a convenient angle, and the display unit can be rotated back and forth when the display unit is turned while the slider is pushed in one direction in the state in which the display is erected. 
     The present invention is also intended to slide a display unit on a body unit without shaking, and to prevent a cable which connects between the body unit and the display unit from being damaged by locating the cable inside the display. 
     The present invention is also intended to provide a portable device which is convenient to carry and use by reducing the thickness of a body unit, the thickness of a display unit, and the size of the display device. 
     The present invention is also intended to provide raise-preventing stepped portions which are disposed on the bottoms of the left and right outer side surfaces of a display unit. The raise-preventing stepped portions prevent the lower part of the display unit from being raised further above the horizontal line of a rotary shaft (i.e. a rotation holding member or a holding member) or the upper part of the display unit from being lowered below the horizontal line of the rotary shaft as the display unit stops sliding upward on a body unit (i.e. stops due to completion of sliding), that is, just before the display unit starts rotation to tilt to a predetermined angle or turn back 180 degrees. In addition, stepped portion slip guide recesses which correspond to the raise-preventing stepped portions are formed along both the sidewalls so that the raise-preventing stepped portions can be inserted into and slide along the inner side surfaces of the sidewalls of the body unit. 
     In order to realize the foregoing object, according to an aspect of the invention, provided is a portable device which includes a display unit and a body unit, the display unit having a display screen disposed on at least one of a front surface and a rear surface. The body unit has sidewalls which protrude forward from left and right side sections of the body unit such that the display unit can rest between the sidewalls. The sidewalls of the body unit include a fixed hinge shaft, one end of the fixed hinge shaft being fixed to a portion of the sidewalls, a portion of the fixed hinge shaft being located inside the display unit. The display unit has a movement hole in a side surface thereof, the portion of the fixed hinge shaft extending through the movement hole such that the display unit can slide on the body unit. 
     According to a characteristic of the invention, it is preferred that the display unit have protrusions on both side surfaces thereof, the protrusions extending in a vertical direction. 
     According to a characteristic of the invention, it is preferred that the protrusions be formed on the side surfaces of the display unit, and 
     the protrusions be formed on predetermined portions of the side surfaces of the display unit except for lower portions of the side surfaces such that the display unit is rotatable about the body unit. 
     According to a characteristic of the invention, it is preferred that the body unit have first guide recesses in inner side surfaces of the sidewalls, the protrusions of the display unit being insertable into the first guide recesses so as to slide, and second guide recesses in front surfaces of the sidewalls which allow the display unit to rotate about the body unit and then closely adjoin the body unit. 
     According to a characteristic of the invention, it is preferred that the portion of the sidewalls of the body unit to which the fixed hinge shaft is fixed be higher than portions where the first guide recesses are formed and be located in the inner side surfaces of the sidewalls of the body unit. 
     According to a characteristic of the invention, it is preferred that a recess which extends in a lateral direction be formed in an upper portion of an area of the body unit between the sidewalls, and that a keyboard be disposed in an area below the recess which extends in the lateral direction. 
     According to a characteristic of the invention, it is preferred that the sidewalls have a battery therein. 
     According to a characteristic of the invention, it is preferred that the battery be disposed in an orientation that is rotated to a predetermined angle to minimize a width and thickness of the sidewalls. 
     According to a characteristic of the invention, it is preferred that the body unit have a circuit board inside a central portion thereof, and that a rear side of the body unit have a metal plate which dissipates heat. 
     According to a characteristic of the invention, it is preferred that the display unit have a display screen which is provided to occupy substantially an entire area of a first surface of the display unit, another display screen which is provided to occupy a portion of a second surface of the display unit, and a printed circuit board is disposed in a remaining portion of the second surface of the display unit. 
     According to a characteristic of the invention, it is preferred that the portable device may further include a cable which transmits at least one of a signal and power between the display unit and the body unit. 
     According to a characteristic of the invention, it is preferred that a portion of the cable be introduced into the body unit through the fixed hinge shaft. 
     According to a characteristic of the invention, it is preferred that the portion of the cable be introduced downward of the body unit through an inside of the fixed hinge shaft and be bent backward of the fixed hinge shaft toward above the body unit. 
     According to a characteristic of the invention, it is preferred that the portion of the cable be attached to a ceiling of a front inner wall of the display unit and be electrically connected to a circuit inside the display unit, and that the cable has a structure that be twisted or bent once before a point where a portion of the cable is attached to the ceiling of the front inner wall. 
     According to a characteristic of the invention, it is preferred that the cable distribute resources between circuits which are respectively included by the body unit and the display unit. 
     According to a characteristic of the invention, it is preferred that the portable device may further include an interlock member having a recess in a surface which faces a sidewall of the sidewalls of the body unit, the interlock member being coupled with the fixed hinge shaft; a rotation holding member which moves integrally with the display unit when the display unit slides and is coupled with the interlock member to serve as a center of rotation when the display unit rotates; and an elastic member which provides elastic force to the rotation holding member. The fixed hinge shaft has a bent central portion. 
     According to a characteristic of the invention, it is preferred that the portable device may further include a fixing stepped portion which prevents the elastic member from being dislodged outward, the fixing stepped portion surrounding and fixing one end of the elastic member. 
     According to a characteristic of the invention, it is preferred that the interlock member have a first linear recess in a surface which is opposite the surface coupled with the corresponding fixed hinge shaft, the first linear recess being formed parallel to a direction in which the display unit slides and closed in one direction, and one or more second linear recesses formed a different angle from the first linear recess, that the rotation holding member have a linear protrusion on a surface which faces a corresponding sidewall of the sidewalls of the body unit, the linear protrusion being formed parallel to the direction in which the display unit slides, and that the linear protrusion of the rotation holding member be insertable into at least one of the first linear recess and the one or more second linear recesses. 
     According to a characteristic of the invention, it is preferred that the display unit may further include a guide rail on an inner wall of a front or rear surface thereof, the guide rail being formed along a path along which the bent central portion of the fixed hinge shaft moves when the display unit slides. 
     According to a characteristic of the invention, it is preferred that the inside of the display unit in which the portion of the fixed hinge shaft is located have a cylindrical shape. 
     According to a characteristic of the invention, it is preferred that the portable device may further include a rotation holding member having a linear protrusion on a surface thereof which faces inward, the linear protrusion being formed substantially parallel to a direction in which the display unit slides; an elastic member which provides restoring force for pushing the rotation holding member outward; and an interlock member having a first linear recess in a surface which faces the fixed hinge shaft, the first linear recess being formed parallel to the direction in which the display unit slides, and one or more second coupling recesses formed at a different angle from the first linear recess. The fixed hinge shaft has an insert recess in a terminal end thereof, the insert recess being formed such that an entrance thereof faces a central portion, the elastic member is disposed inside the insert recess, and the central portion of the fixed hinge shaft has a flat shape. 
     According to a characteristic of the invention, it is preferred that the interlock member move integrally with the display unit when the display unit slides and be coupled with the rotation holding member to serve as a center of rotation when the display unit rotates. 
     According to a characteristic of the invention, it is preferred that the insert recess have a fixing stepped portion, that the rotation holding member have a stepped portion such that an outer portion thereof is thicker, and that the fixing stepped portion of the insert recess and the stepped portion of the rotation holding member prevent the rotation holding member from being dislodged from the insert recess. 
     According to a characteristic of the invention, it is preferred that the display unit further include a protective film disposed inside a sidewall thereof, the protective film closing the movement hole from an outside, the protective film being made of an elastic material. 
     According to a characteristic of the invention, it is preferred that a portion of the protective film which adjoins the fixed hinge shaft has a circular shape. 
     According to a characteristic of the invention, it is preferred that the display unit further include a protective film-receiving recess in an upper part thereof adjacent to the inner sidewall, the protective film-receiving recess being laterally formed. A portion of the protective film enters and exits the protective film-receiving recess as the display unit slides on the body unit. 
     According to a characteristic of the invention, it is preferred that the fixed hinge shaft be divided into two sections and further include a ring which surrounds the two sections in order to prevent the two sections from being widened by external force. 
     According to a characteristic of the invention, it is preferred that raise-preventing stepped portions be disposed on the bottoms of the left and right outer side surfaces of a display unit. The raise-preventing stepped portions prevent the lower part of the display unit from being raised further above the horizontal line of a rotary shaft (i.e. a rotation holding member or a holding member) or the upper part of the display unit from being lowered below the horizontal line of the rotary shaft as the display unit stops sliding upward on a body unit (i.e. stops due to completion of sliding), that is, just before the display unit starts rotation to tilt to a predetermined angle or turn back 180 degrees. It is also preferred that stepped portion slip guide recesses which correspond to the raise-preventing stepped portions be formed along both the sidewalls so that the raise-preventing stepped portions can be inserted into and slide along the inner side surfaces of the sidewalls of the body unit. 
     According to another aspect of the invention, provided is a portable device which includes a display unit and a body unit, the display unit having a display screen disposed on at least one of a front surface and a rear surface. The body unit has sidewalls which protrude from left and right side sections of the body unit such that the display unit rests between the sidewalls. The sidewalls of the body unit include a holding member, one end of the holding member being fixed to a portion of the sidewalls, a portion of the holding member being located inside the display unit. The display unit has a movement hole in a side surface thereof, the portion of the holding member extending through the movement hole such that the display unit can slide on the body unit. 
     According to a characteristic of the invention, it is preferred that the display unit have a rotary hinge shaft in a side portion thereof, the rotary hinge shaft being configured as a C-shaped ring which has an opening, the opening being formed in a direction opposite to a direction in which the display unit slides, such that the holding member can rest into the rotary hinge shaft configured as the C-shaped ring through the opening. 
     According to a characteristic of the invention, it is preferred that an interlock member be disposed in at least a portion of the holding member, the interlock member surrounding an outer circumference of the holding member, an outer diameter of the interlock member being equal to an outer diameter of the rotary hinge shaft, the interlock member adjoining the rotary hinge shaft when the holding member rests inside the rotary hinge shaft, and that an elastic member be disposed between one end of both ends of the interlock member and one end of both ends of the holding member which are disposed on a sidewall of the sidewalls of the body unit, the elastic member surrounding the holding member. 
     According to a characteristic of the invention, it is preferred that surfaces of the rotary hinge shaft and the interlock member which adjoin each other have a plurality of protrusions and recesses, and that elastic force of the elastic member be maximum when the protrusions formed on the rotary hinge shaft adjoin the protrusions formed on the interlock member. 
     According to a characteristic of the invention, it is preferred that a cable through-hole be formed in an axial direction in the holding member. 
     According to a characteristic of the invention, it is preferred that the portable device further include a guide rail extending from the opening of the rotary hinge shaft, the guide rail guiding a movement of the holding member when the display unit slides. 
     According to embodiments, the guide recesses in the front surface of the display unit of the portable device are closed at one end. When the display unit is flipped and turned back such that the second surface of the display unit faces forward, the protrusions on the opposite side surfaces of the display unit can be fixedly inserted into the recesses in the front surface of the body unit. Since the stepped portions are formed, it is easy to hold the device with the hand. In addition, the thickness of the display unit can be advantageously reduced. 
     According to embodiments, since the body unit of the portable device has the fixed hinge shaft and the cable is drawn through a portion of the fixed hinge shaft, the cable is prevented from wearing, which is advantageous. 
     According to embodiments, since the body unit has the recesses and the display unit has the protrusions which are to be inserted into the recesses of the body unit, there is an advantageous effect in that vibration which occurs when the display unit slides on the body unit can be prevented. 
     According to embodiments, the display unit of the portable device has the movement holes through which predetermined portions of the fixed hinge shaft can move and the protective rails or protective films which close the movement holes from inside, thereby blocking the inside of the display unit from the outside. As advantageous effects, it is possible to prevent foreign matters from entering and prevent the cable or the like inside the display unit from being damaged by a pen or an awl. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a portable device according to an embodiment of the invention; 
         FIG. 2  is a view showing the display unit of the portable device according to an embodiment of the invention which is slid and rotated to a predetermined angle; 
         FIG. 3  is a view showing a second surface of the display unit of the portable device according to an embodiment of the invention which is directed upward; 
         FIG. 4A  is an exploded perspective view showing respective components of a portable device according to a first embodiment of the invention; 
         FIG. 4B  shows the display unit of the portable device according to the first embodiment of the invention; 
         FIG. 5A  to  FIG. 5D  are perspective views showing the display unit of the portable device according to the first embodiment of the invention which sequentially moves on the body unit; 
         FIG. 6A  is a front view showing the portable device according to the first embodiment of the invention; 
         FIG. 6B  is a side elevation view showing the portable device according to the first embodiment of the invention; 
         FIG. 7A  and  FIG. 7B  are enlarged views showing the fixed hinge shaft of the portable device according to the first embodiment of the invention; 
         FIG. 8A  is a perspective view showing a portable device according to another embodiment of the invention; 
         FIG. 8B  is a front view showing the portable device according to another embodiment of the invention 
         FIG. 9A  and  FIG. 9B  are enlarged views of the fixed hinge shaft of the portable device according to another embodiment of the invention; 
         FIG. 10  is an exploded perspective view illustrating the structure of a portable device according to a second embodiment of the invention; and 
         FIGS. 11A and 11B  are perspective views showing the display unit of the portable device according to the second embodiment of the invention which sequentially moves on the body unit. 
         FIG. 12  is a view showing the state in which the lower part of the display unit cannot be raised further above the horizontal line of the rotary shaft just before the display unit starts tilting or rotating after it has stopped sliding. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. It is to be understood that the accompanying drawings are illustrated for the enhancement of understanding of the present invention. It will be apparent to a person having ordinary skill in the art that the scope of the invention is not defined by the accompanying drawings. 
     EXEMPLARY EMBODIMENTS OF THE INVENTION 
     Overall Construction of Portable Device 
       FIG. 1  is a perspective view showing a portable device according to an embodiment of the invention. 
     The portable device includes a display unit  110  and a body unit  120 . The display unit  110  includes a first display  130 , and is positioned such that a first surface  135  faces forward. Buttons  140  can be positioned in the upper portions of the left and right sections of the body unit  120 . Here, the state in which the first display  130 , i.e. a wide display, faces forward is defined as a first mode of the portable device, whereas the state in which a second display  170  smaller than the first display  130  faces forward is defined as a second mode of the portable device. Although the first display  130  is defined to be greater than the second display  170  for the sake of description, the scope of the invention is not limited thereto. Rather, the sizes of displays can vary depending on the design. 
       FIG. 2  is a view showing the display unit of the portable device according to an embodiment of the invention which is slid and rotated to a predetermined angle. The display unit  110  can slide upward and parallel to the body unit  120 . After the display unit  110  has completed sliding, the display unit  110  can rotate about a reference shaft. The portable device  100  which has rotated to a predetermined angle can expose a keyboard  160  inside the body unit  120 . The keyboard  160  is exposed outward when the portable device is converted from the first mode into another mode. In this state, a user can use the portable device as a computer using the keyboard  160  and the first display  130 . 
       FIG. 3  is a view showing the second surface of the display unit of the portable device according to an embodiment of the invention which is directed upward. 
     When the display unit  110  shown in  FIG. 2  is rotated further (e.g. to 180 degrees), the display unit is coupled with the body unit. That is, the portable device is arranged such that a second surface  175  of the display unit  110  faces upward. The second display  170  and a keypad  180  can be disposed on the second surface  175 . As defined above, the state of the portable device in which the second display  170  faces upward can be defined as the second mode. The user can use the portable device as a mobile phone using the second display  170  and the keypad  180 . Although an example for the keypad  180  and the second display  170  is shown in  FIG. 3  in order to describe the concept of the invention, the scope of the invention is not limited thereto. The arrangement of keys of the keypad  180  and the shape, size or the like of the second display  170  can be changed. 
     Detailed descriptions will be given below of respective components of portable devices according to various embodiments of the invention. 
     First Embodiment 
       FIG. 4A  is an exploded perspective view showing respective components of a portable device according to a first embodiment of the invention, and  FIG. 4B  shows only the display unit of these components. 
     The body unit  120  of the portable device has sidewalls  410  on left and right sections of the body unit. The sidewalls  410  protrude such that they face left and right side surfaces of the display unit  110  so that the display unit  110  can rest therebetween. The body unit  120  also has fixed hinge shafts  400  which are respectively fixed to predetermined portions of the sidewalls  410 . The fixed hinge shafts  400  are partially located inside the display unit  110 . The display unit  110  has movement holes  425  formed in side surfaces thereof. Predetermined portions of the fixed hinge shafts  400  respectively extend through the movement holes  425  such that the display unit  110  can slide on the body unit  120 . Circular holes  435  are respectively formed on terminal ends of the movement holes  425  such that the fixed hinge shafts  400  rotate inside the circular holes  435  when the display unit  110  rotates. 
     The display unit  110  can include protrusions  430  on both side surfaces thereof, the protrusions extending in the vertical direction. The protrusions  430  can be formed on predetermined portions of the side surfaces of the display unit  110  such that the display unit  110  can rotate about the body unit  120 . First guide recesses  405  are respectively formed in inner surfaces of the sidewalls  410  of the body unit  120  such that the protrusions  430  of the display unit  110  can be inserted into and slide in the guide recesses  405 . Second guide recesses  415  can be respectively formed in the front sections of the sidewalls  410  of the body unit  120  such that the display unit  110  can closely adjoin the body unit  120  after having rotated about the body unit  120 . The first guide recesses  405  of the body unit  120  and the protrusions  430  of the display unit  110  serve to prevent vibration when the display unit  110  is sliding, so that the display unit  110  can smoothly slide. 
     Portions where the fixed hinge shafts  400  are respectively coupled with the sidewalls  410  of the body unit  120  are higher than portions in which the first guide recesses  405  are formed and are located in the inner side surfaces of the sidewalls  410  of the body unit  120 . That is, the fixed hinge shafts  400  are located adjacent to end portions of the sidewalls  410 , serve as the center of rotation when the display unit  110  rotates, and serve as a stopper which prevents the display unit  110  from sliding any further when the display unit  110  is moving in the second mode after having slid in the first mode. 
     A recess  480  which extends in the lateral direction, i.e. in the left-right direction, can be formed in the upper portion of the area of the body unit  120  between the sidewalls  410 . The recess  480  helps the display unit  110  smoothly rotate without interruption, and serves to support and guide the display unit  110 . The keyboard  160  can be disposed in a portion below the recess  480 . 
     Recesses can be respectively formed in the surfaces of the body unit  120  that face the sidewalls. Due to this configuration, interlock members  450  which are coupled with the fixed hinge shafts  400  can be formed on terminal ends of the fixed hinge shafts  400 . Here, it is preferred that the interlock members have a cylindrical shape such that the display unit  110  can rotate. 
     Rotation holding members  485  can also be provided. When the display unit slides, the rotation holding members  485  integrally move along with the display unit  110 . When the display unit  110  rotates, the rotation holding members  485  are coupled with the interlock member  450  and serve as the center of rotation together with the interlock member  450 . 
     Each of the rotation holding members  485  can have an elastic member  475  on one end thereof which provides elastic force. The side cross-section of the rotation holding members  485  can have a shape selected from among a circle, a quadrangle, a polygon or the like. 
     It is preferred that the fixed hinge shafts  400  be configured such that the central portion thereof is bent. 
     Each of the interlock members  450  can have a first linear recess  455  in a surface which is opposite the surface coupled with the corresponding fixed hinge shaft  400 . The first linear recess  455  is formed parallel to the direction in which the display unit  110  slides. Each of the interlock members  450  can also has one or more second linear recesses  460  which are formed at a different angle from the first linear recess  455 . Each of the rotation holding members  485  has a linear protrusion  470  on the surface thereof that faces the corresponding sidewall  410  of the body unit  120 . The linear protrusion  470  is parallel to the direction in which the display unit slides. Each linear protrusion  470  of the rotation holding member can be configured such that it can be inserted into at least one of the first linear recess  455  and the second linear recesses  460 . 
     The first linear recesses  455  are closed only in one direction. This is because the first linear recesses  455  must be closed in one direction such that the linear protrusions  470  of the rotation holding members  485  are caught so that the display unit  110  which has slid from the first mode is fixed just before it rotates. 
     In addition, the display unit  110  can also include guide rails  420  on inner walls of the front or rear surface thereof. The guide rails  420  are formed along a path along which the bent central portions of the fixed hinge shafts  400  move during the sliding. The guide rail  420  can protect the inside of the display unit  110  which would otherwise be exposed through the movement holes  425 . In particular, since cables or the like which are located inside the display unit  110  can be damaged through the movement holes  425 , the guide rails  420  protect these components. The guide rails also serve to help the display unit move along the fixed hinge shafts  400  without vibration. 
     In addition, it is preferred that the inside of the display unit  110  in which predetermined portions of the fixed hinge shafts  400  are located have a cylindrical shape. That is, the circular holes  435  formed in the display unit  110  have a cylindrical shape. 
       FIG. 5A  to  FIG. 5D  are perspective views showing the display unit of the portable device according to an embodiment of the invention which has sequentially moved about the body unit. 
       FIG. 5A  shows the display unit  110  and the body unit  120  of the portable device which closely adjoin each other, in which the first surface of the display unit  110  faces forward. In this state, a user can slide the display unit  110  by applying force thereto in two o&#39;clock direction on the paper surface. Then, the display unit  110  can smoothly move and slide, since the protrusions  430  closely adjoin the first guide recesses of the sidewalls, thereby reducing vibration. The elastic members  475  and the rotation holding members  485  integrally move with the display unit  110 , since they are fixed to the display unit  110 . 
       FIG. 5B  is a view showing the state in which the display unit  110  has completed sliding and cannot slide any further. After the display unit  110  has started sliding, the display unit  110  stops sliding at the moment that the linear protrusions  470  of the rotation holding members  485  are inserted into the recesses of the interlock members  450 . Since the recesses of the interlock members  450  are partially closed by stepped portions, the display unit cannot move further outward in the horizontal direction. While the display unit  110  is sliding, the movement holes  425  stay closed by the guide rails  420 . Therefore, it is possible to prevent external foreign matters from entering the inside of the display unit  110 . It is also possible to prevent a cable from being damaged by a sharp tool such as an awl. 
     In addition, the cable  510  is disposed such that it is drawn from the body unit  120  and extends through the central portion of the fixed hinge shaft  400 . After the cable  510  is drawn downward of the display unit  110  from the central portion of the fixed hinge shaft  400 , it is twisted or bent once, and extends across the space below the fixed hinge shaft  400 . After the cable  510  passes through the space below the fixed hinge shaft  400 , it is twisted or bent once and then adjoins and is coupled with the area of the display unit  110  adjacent to the ceiling. Alternatively, the cable  510  adjoins and is coupled with the area of the display unit  110  opposite the ceiling without being twisted or bent. 
       FIG. 5C  is a view showing the display unit  110  which has rotated and is at an incline when the display unit  110  is rotated about the sidewalls  410 . When the display unit has completed sliding, the linear protrusions  470  of the rotation holding members are inserted into the horizontal recesses of the interlock members  450  attached to the terminal ends of the fixing hinge shafts  400  of the display unit  110 . When force for rotating the display unit  110  is applied in this state, the rotation holding members  485 , each of which has each elastic member  475  inserted into one end thereof, slightly retract due to elastic contraction. When the display unit  110  is rotated further from this position, the linear protrusions  470  of the rotation holding members  485  can be engaged into one or more recesses that have a different angle from the horizontal recesses of the interlock members  450 . That is, the linear protrusions  470  of the rotation holding members  485  are inserted into the recesses of the interlock members  450  due to elastic force generated by the elastic members  475 . 
     In this fashion, the display unit  110  is fixed at a predetermined angle (e.g. 30°, 45°, 60° or the like) with respect to the body unit  120 . Consequently, the user can use the portable device as a small computer using the keyboard  160  disposed on the body unit  120  and the first display  130  of the display unit  110 . A variety of commercially distributed operating systems (OS) loaded in the portable device in order to control the operation of the portable device. 
       FIG. 5D  is a view showing the display unit  110  which has been rotated further from the position shown in  FIG. 3C  so that the second display  170  and the keypad of the display unit face forward. 
     When force for rotating the display unit  110  is applied, the linear protrusions  470  on terminal ends of the rotation holding members of the display unit are forced to dislodge from the interlock members  450 . This force causes the elastic members  475  to be pushed backward and the linear protrusions  470  are dislodged from the recesses. Since the linear protrusions  470  of the rotation holding members  485  are dislodged from the recesses of the interlock members  450 , the display unit  110  can be rotated by a small amount of force. The rotation fixing shafts  400  act as the center of rotation, and are surrounded by the circular holes  435  which are formed in the side surfaces of the display unit  110  and have the shape of a cylinder, so that the rotation can be smoothly carried out. 
     When the rotation has been completed, the protrusions  430  of the display unit  110  are closely inserted into the second guide recesses  415  of the body unit  120 . It is preferred that the sidewalls  410  and the inserted protrusions  430  be designed such that there are no stepped portions therebetween. 
       FIG. 6A  is a front view showing a portable device according to an embodiment of the invention. 
     In addition to the above-described features, the body unit  120  has another advantage in that the thickness of the central portion of the body unit  120  can be reduced by disposing batteries  610  in both side sections such that they are oriented at predetermined angles. In addition, the bottom of the body unit  120  can be made of metal. When the bottom of the body unit  120  is made of metal, it is possible to easily dissipate heat that has been generated from a printed circuit board (PCB)  615  which is located in the central portion of the body unit and on which components and circuits are mounted. Consequently, it is not required to dispose an additional heat dissipating member inside the body unit  120 , which is advantageous. The body unit  120  also has the keyboard  160  on the top portion thereof. The display unit  110  includes the first display  130 , the second display  170  and the keypad  180 . 
     The first display  130  of the display unit  110  basically operates together with the keyboard  160  of the body unit  120 , and is operated by a processor, a memory or the like which is equipped in the body unit  120 . Signals can be transmitted between the keyboard  160  and the first display  130  via the cable  510 . 
     In addition, the cable  510  also allows semiconductor components, processors and memories which are disposed on the PCB  615  of the body unit  120  to share resources with semiconductor components, processors and memories which are disposed on a PCB  630  of the display unit  110 . That is, the processors or memories in one part can use resources of the processors or memories in the other part when their capacities are insufficient. 
       FIG. 6B  is a side elevation view showing the portable device according to an embodiment of the invention. 
     The movement holes  425  or protrusions  430  can be formed in both side surfaces of the display unit  110 , and the circular holes  435  can be formed on the terminal ends of the movement holes  425 . The protrusions  430  are configured such that they can respectively rest in the second guide recesses  415  of the body unit. 
       FIG. 7A  and  FIG. 7B  are enlarged views showing one of the fixed hinge shafts  400  of the portable device according to an embodiment of the invention. 
     The fixed hinge shaft  400  is fixed to the sidewall  410  of the body unit  120 , and stays fixed to the body unit  120  without movement while the display unit  110  is rotating. In addition, the cable  510  is disposed through the inside of the fixed hinge shaft  400 , such that it is not damaged by external impacts in spite of rotation of the display unit  110 . The protrusion  430  of the display unit  110  rests in the first guide recess  405  of the body unit  120 . Consequently, when the display unit  110  is sliding, vibration is not applied. 
     The guide rail  420  is configured such that it can close the movement hole, thereby preventing foreign matters from entering and the inside cable or circuit from being damaged by a sharp object. The elastic member  475  provides the rotation holding member  485  with restoring force. The restoring force allows the protrusion  470  to be attached to or detached from the linear recess  455 . The body unit  120  can also include the PCB therein. A fixing stepped portion  476  which prevents the elastic member  475  from being dislodged outward, the fixing stepped portion  476  surrounding and fixing one end of the elastic member  475 . The elastic member  475  is disposed inside the insert recess  411 , and the central portion of the fixed hinge shaft has a flat shape. 
       FIG. 8A  is a perspective view showing a portable device according to another embodiment of the invention, and  FIG. 8B  is a front view showing the portable device according to another embodiment of the invention. 
     In this embodiment, fixed hinge shafts  800  have a linear shape (linear fixed hinge shafts). The advantage is that the width of the display unit  110  can be decreased more. The display unit  110  can include protective films  850  inside the sidewalls thereof such that the fixed hinge shafts  800  have the linear shape. The display unit  110  includes the protective films  850  disposed inside the sidewalls thereof. The protective films  850  close the movement holes  425  of the display unit  110  from the outside, and can be made of an elastic material. Since the protective films  850  which can close the movement holes  425  are provided in place of the guide rails  420  which were described in the foregoing embodiment, the inside of the display unit  110  is protected. Since the protective films  850  are made of an elastic material, they can be bent while the display unit  110  is sliding. In addition, each protective film  850  has a circular hole, which surrounds each central portion of the fixed hinge shafts  800 . 
     Protective film-receiving recesses  860  are formed in the horizontal direction in the upper part of the display unit  110  adjacent to the inner sidewall. As the display unit  110  slides on the body unit  120 , portions of the protective films can enter or exit the protective film-receiving recesses  860 . According to the embodiment shown in  FIG. 8A , it shall be assumed that the display unit  110  slide in the first mode and be separated from the body unit  120 . Specifically, the protective films  850  are located inside the protective film-receiving recesses  860  when the display unit  110  is in the first mode. As the display unit slides in the first mode, the protective films  850  slip from the protective film-receiving recesses  860 , thereby closing the movement holes  425  formed in the display unit  110 . 
     In this embodiment, each of the fixed hinge shafts  800  is configured as two sections, and can also include a ring which surrounds the two sections in order to prevent the two sections from being widened by external force. 
       FIG. 9A  and  FIG. 9B  are enlarged views of one of the fixed hinge shafts  800  of the portable device according to another embodiment of the invention. 
     The fixed hinge shaft  800  has a linear shape without bends, and an elastic member  810  is located adjacent to the fixed hinge shaft  800 . A coupling protrusion  830  is formed at a position outside the elastic member, and one or more coupling recesses  840  are formed in a rotation fixing section  820  which is opposite the coupling protrusion. Since the horizontal recess of one or more coupling recesses  840  is closed at one end thereof as described above, the display unit  110  which has been sliding in the horizontal direction is fixed and stops. When rotating force is applied to the display unit  110 , the coupling protrusion  830  which has been supported by the elastic member  810  is decoupled from the coupling recess  840  and is then coupled with the coupling recess  840  having a different angle. Based on this principle, the display unit  110  can be fixed at a predetermined angle with respect to the body unit  120 . 
     According to this embodiment, the fixed hinge shaft  800  has a linear shape instead of a curved shape, it is possible to remove as much empty space as possible inside the display unit  110 , thereby advantageously reducing the width of the display unit  110 . 
     Second Embodiment 
       FIG. 10  is an exploded perspective view illustrating the structure of a portable device according to a second embodiment of the invention. 
     In the second embodiment, the structures of a body unit  120   a , a display unit  110   a , sidewalls  410   a , protrusions  430   a , guide recesses  405   a , grooves  480   a , and a keyboard  160   a  are the same as those of the first embodiment which are designated with corresponding reference numerals. Therefore, descriptions thereof will be omitted herein for the sake of brevity. 
     According to the second embodiment, holding members  485   a  that can be considered to correspond to the rotation holding members  485  of the first embodiment are partially inserted into the sidewalls  410   a  instead of the inside of the display unit  110   a . Each of the holding members  485   a  is configured such that one portion thereof is inserted into the sidewall  410   a  and the other portion thereof is inserted into the display unit  110   a  such that it can move. In addition, unlike the first embodiment, rotary hinge shafts  400   a  which can be considered to correspond to the fixed hinge shafts  400  of the first embodiment are inserted into the display unit  110   a . Each of the rotary hinge shafts  400   a  is configured as a C-shaped ring in which a portion of the respective holding member  485   a  that is inserted into the display unit  110   a  can rest in the ring. Thus, when the display unit  110   a  slides on the body unit  120   a , the holding members  485   a  are introduced into the openings of the rotary hinge shafts  400   a  which are configured as a C-shaped ring. After the holding members  485   a  have been introduced into the rotary hinge shafts  400   a , the rotary hinge shafts  400   a  serve as a stopper, thereby causing the display unit  110   a  to stop sliding on the body unit  120   a.    
     The display unit  110   a  has movement holes  425   a  formed in the side surfaces thereof. Predetermined portions of the holding members  485   a  respectively extend through the movement holes  425   a  such that the display unit  110   a  can slide on the body unit  120   a . The width of each movement hole  425   a  is determined to be equal to or greater than the width of the sliding surface of each holding member  485   a  which protrudes beyond protrusions and recesses formed in the circumference of an interlock member  470   a , such that the holding member  485   a  can smoothly move without friction. 
     Each holding member  485   a  is located in the inner surface of the sidewall  410   a  of the body unit  120   a , specifically, adjacent to one end of the inner surface (i.e., an end portion), and serves as the center of rotation when the display unit  110   a  rotates. When the display unit  110   a  is moving in the second mode after having slid from the first mode, the holding member also acts as a stopper which prevents the display unit from sliding any further. 
     The interlock member  470   a  is formed on at least a portion of the holding member  485   a . The interlock member  470   a  surrounds the outer circumference of the holding member  485   a  and engages with the rotary hinge shaft  400   a . One end of the interlock member  470   a  engages with the rotary hinge shaft  400   a , and the other end of the interlock member  470   a  and one end of opposite ends of the holding member  480   a  which is disposed inside the body unit  120   a  are connected to each other via an elastic member  475   a  which surrounds the outer circumference of the holding member  485   a . The elastic member  475   a  provides the interlock member  470   a  with elastic force that is in the axial direction of the holding member  485   a , using one end of the holding member  485   a  as a fixed end. In the opposite ends of the elastic member  475   a , one end is fixed to the terminal end of the fixed member  485   a  and the other end is fixed to one end of the interlock member  470   a  in order to prevent the interlock member  470   a  which surrounds the outer circumference of the holding member  485   a  from being separated from the holding member  485   a . According to a preferred embodiment, as shown in  FIG. 10 , one end of the opposite ends of the holding member  485   a  which is disposed inside the body unit  102   a  has a fixing stepped portion. An insert recess can be formed in the fixing stepped portion. The distal end of the elastic member  475   a  which has the shape of a spring can be inserted into the insert recess. The distal end that has been inserted into the insert recess can be bent and fixed to the insert recess. In addition, as shown in  FIG. 10 , a fixing stepped portion can also be formed on one end of the opposite ends of the interlock member  470   a  which adjoins the elastic member  475   a . The distal end of the elastic member  475   a  can be inserted into the insert recess formed in the fixing stepped portion of the interlock member  470   a . The distal end that has been inserted into the insert recess can be bent and fixed to the insert recess. In this fashion, the elastic member  475   a  can be fixed between one end of the holding member  485   a  and the interlock member  470   a , thereby preventing the interlock member  470   a  from being separated or dislodged. 
     The outer diameter of the interlock member  470   a  is formed to be equal to the outer diameter of the rotary hinge shaft  400   a , such that the outer circumference of the interlock member  470   a  adjoins and engages with the outer circumference of the rotary hinge shaft  400   a . A protrusion and a recess are respectively formed in the circumference of the interlock member  470   a  and the circumference of the rotary hinge shaft  400   a . It is preferred that the circumference of the interlock member  470   a  and the circumference of the rotary hinge shaft  400   a  be formed in the shape of waves. When the recess of the interlock member  470   a  and the protrusion of the rotary hinge shaft  400   a  engage with each other or the protrusion of the interlock member  470   a  and the recess of the rotary hinge shaft  400   a  engage with each other, the elastic force of the elastic member  475   a  is minimized. In contrast, when the protrusion of the interlock member  470   a  and the protrusion of the rotary hinge shaft  400   a  adjoin each other, the elastic force of the elastic member  475   a  is maximized. Consequently, the interlock member  470   a  and the rotary hinge shaft  400   a  can firmly engage with each other at a point where the elastic force of the elastic member  475   a  is minimized. That is, the interlock member  470   a  and the rotary hinge shaft  400   a  engage with each other such that the display unit  110   a  and the body unit  120   a  are fixed at a predetermined angle (e.g. 30°, 45°, 60° or the like) with respect to each other, and rotate in this state. 
       FIGS. 11A and 11B  are perspective views showing the display unit  110   a  of the portable device according to the second embodiment of the invention which sequentially moves on the body unit  120   a.    
       FIG. 11A  shows the display unit  110   a  and the body unit  120   a  of the portable device which closely adjoin each other in the state where the first surface of the display unit  110   a  faces forward. In this state, the user can slide the display unit  110   a  by applying force thereto in two o&#39;clock direction on the paper surface. 
       FIG. 11B  is a view showing the display unit  110   a  which has completed sliding and cannot slide any further. After the display unit  110   a  has started sliding, it stops sliding when the holding member  485   a  is inserted into the opening of the rotary hinge shaft  400   a  which is configured as the C-shaped ring and is stopped by the hinge shaft  400   a . The opening of the rotary hinge shaft  400   a  can be in contact with the guide rail  420   a . The guide rail  420   a  helps the holding member  485   a  to reliably move when the display unit is sliding, and allows the holding member  485   a  to safely rest inside the rotary hinge shaft  400   a.    
     At the moment that the holding member  485   a  rests inside the rotary hinge shaft  400   a , the protrusion of the interlock member  470   a  which surrounds the outer circumference of the holding member  485   a  and the recess of the rotary hinge shaft  400   a  engage with each other and the recess of the interlock member  470   a  and the protrusion of the rotary hinge shaft  400   a  engage with each other. 
     Afterwards, the holding member  485   a  rotates inside the rotary hinge shaft  400   a . When the holding member  485   a  rotates, the interlock member  470   a  and the rotary hinge shaft  400   a  engage with each other. When the interlock member  470   a  and the rotary hinge shaft  400   a  rotate in the engaged state, the elastic force of the elastic member  475   a  is adjusted in the axial direction of the holding member  485   a . As the holding member  485   a  and the rotary hinge shaft  400   a  rotate about each other, the display unit  110   a  rotates at a predetermined angle about the body unit  120   a . Here, the interlock member  470   a  and the rotary hinge shaft  400   a  also rotate about each other. In this process, when the protrusion of the interlock member  470   a  and the protrusion of the rotary hinge shaft  400   a  adjoin each other, the elastic force of the elastic member  475   a  becomes maximum. Therefore, the interlock member  470   a  and the rotary hinge shaft  400   a  are characterized in that their protrusion and recess engage with each other. Consequently, the interlock member  470   a  and the rotary hinge shaft  400   a  stop rotation whenever the protrusion and the recess engage with each other. Accordingly, the display unit  110   a  engages with and rotates about the body unit  120   a  such that it is fixed at a predetermined angle (e.g., 30°, 45°, 60° or the like) with respect to the body unit. 
     The display unit  110   a  continuously rotates until it has the relationship with respect to the body unit  120   a  as shown in  FIG. 5C  and  FIG. 5D . This process is the same as that of the first embodiment, and thus descriptions thereof will be omitted. 
     A cable through-hole H axially extends through the holding member  485   a , and the cable (not shown) which is drawn from the body unit  120   a  passes through the cable through-hole H. The cable which has passed through the cable through-hole H can be drawn to the display unit  110   a  and be fixed thereto. The cable may be implemented as a flexible printed circuit board (FPCB) or the like. 
     According to the second embodiment of the invention, the rotary hinge shaft  400   a  is configured as a C-shaped ring. The width of the rotary hinge shaft is the same as the width of the guide rail  420   a . Since the holding member  485   a  and the elastic member  475   a  are disposed on the body unit  120   a  instead of the display unit  110   a , components which are housed in the display unit  110   a  can be simplified. Accordingly, the width of the display screen of the display unit  110   a  can be further increased, whereas the thickness thereof can be decreased. 
       FIG. 12  is a view showing the state in which the lower part of the display unit  110  or  110   a  cannot be raised further above the horizontal line of the rotary shaft (i.e. the rotation holding member or the holding member) just before the display unit  110  or  110   a  starts tilting or rotating after it has stopped sliding. 
     Raise-preventing stepped portions  201  are disposed on the bottoms of the left and right outer side surfaces of the display unit  110  or  110   a . The raise-preventing stepped portions  201  prevent the lower part of the display unit  110  or  110   a  from being raised further above the horizontal line of the rotary shaft (i.e. the rotation holding member or the holding member) or the upper part of the display unit  110  or  110   a  from being lowered below the horizontal line  200  of the rotary shaft as the display unit  110  or  110   a  stops sliding upward on the body unit  120  or  120   a  (i.e. stops due to completion of sliding), that is, just before the display unit  110  or  110   a  starts rotation to tilt to a predetermined angle or turn back 180 degrees. In addition, stepped portion slip guide recesses  202  which correspond to the raise-preventing stepped portions  201  are formed along both the sidewalls so that the raise-preventing stepped portions  201  can be inserted into and slide along the inner side surfaces of the sidewalls of the body unit  120  or  120   a.    
     As set forth above, it is apparent to a person having ordinary skill in the art that various changes in forms and details may be made therein without departing from the spirit and essential features of the present invention. 
     Accordingly, the foregoing embodiments should be regarded as illustrative rather than limiting. The scope of the present invention is not defined by the detailed description as set forth above but by the accompanying claims of the invention. It should also be translated that all alterations or modifications derived from the definitions and scopes of the claims and their equivalents fall within the scope of the invention.