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CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled “A Method for Controlling Opening and Closing of Sub-Body in Automatically and Manually Foldable Portable Mobile Communication Terminal” earlier filed in the Korean Industrial Property Office on Feb. 16, 2001 and thereby duly assigned Serial No. 07886/2001 by the Office. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a mobile telephone terminal, and in particular, to an apparatus and a method for controlling opening and closing of a sub-body in an automatically and manually foldable mobile communication terminal. 
     2. Description of the Related Art 
     A mobile radio terminal is a portable mobile station that provides radio communication services to its subscriber while wirelessly communicating with a base station. Mobile telephone terminals are generally classified into two types of terminals, i.e., a bar-type terminal and a foldable terminal. The bar-type terminal with its keypad exposed to the outside, has recently trended toward less popular use due to its exposed keypad providing no protection against any careless use. On the other hand, the foldable terminal provided with a main body and a sub-body, which is foldably coupled to the main body so that it is designed to fully cover a keypad disposed on the main body, is winning much more popularity for its compact size and good protection for its keypad. 
     Conventionally, the foldable terminals are classified into a flip-type terminal, a flip-up-type terminal and a folder-type terminal. The flip-type terminal has a flip cover that serves as a sub-body for protecting the keypad mounted on a main body and concentrating a user&#39;s voice into a microphone mounted on the main body. The flip-up-type terminal is analogous to that of the flip-type in appearance, but further featured by a flip cover capable of opening up toward the upper side of the main body. The folder-type terminal has at least one display assembly consisting of one or more Liquid Crystal Display (LCD) modules mounted on either an inside or an outside, or both, of the sub-body other than a main body of the foldable terminal. 
     In recent years, customer need for a more convenient portable terminal has given rise to a so-called automatic foldable terminal designed to open and close the sub-body (usually referred to as a “folder”) automatically as well as manually, by means of driving a folder motor disposed inside the terminal. Therefore, it is noted that such an automatic foldable terminal requires a more efficient and precise control for driving the motor opening or closing the sub-body. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an apparatus and a method for more efficiently and precisely controlling the position of opening and closing a sub-body (folder) of an automatic foldable mobile communication terminal. 
     To achieve the above and other objects of the present invention, there is provided an apparatus for controlling opening and closing of a folder in a foldable mobile communication terminal having a main body and a sub-body foldably mounted on the main body. The apparatus comprises: a sensor means arranged in the vicinity of one end of the main-body and the sub-body, for detecting a fully open status or a fully closed status of the sub-body on the main-body; a sub-body opening and closing drive unit for automatically opening or closing the sub-body by means of activating a sub-body drive motor rotatably coupled with the one end of the sub-body; and a current sensing unit coupled to the control unit for sensing the amount of motor drive current applied to the sub-body drive motor and providing the sensed amount of motor drive current to a control unit. The control unit takes a measurement of the amount of the motor drive current output from the current sensing unit upon enabling of an automatic opening or closing operation of the sub-body in the sub-body opening and closing drive unit, and then discontinues to drive the sub-body drive motor when the measured amount of the motor drive current is larger than a predetermined current threshold value and the sensor means senses either one of a fully open status or a fully closed status of the sub-body. 
     Preferably, the apparatus includes a first magnet disposed in a hinge, which is provided with the sub-body opening and closing drive unit, rotatably connected to one end of the sub-body and the main-body, a second magnet mounted inwardly on an inner surface of the sub-body spaced apart from the hinge, an opening sensor disposed in the vicinity of the hinge, on one end of an lower surface of a printed circuit board inside the main-body for providing the control unit with a first sensing signal when the first magnet is placed in close proximity to the opening sensor, and a closing sensor disposed in a position opposing to the second magnet spaced apart from the hinge on the printed circuit board. The closing sensor provides the control unit with a second sensing signal when the second magnet is placed in close proximity to the closing sensor. 
     According to another aspect of the present invention, there is provided a method for controlling automatic opening and closing of a folder in a foldable mobile communication terminal having a main body, a sub-body foldably mounted on the main body, a sensor means for detecting a fully open status or a fully closed status of the sub-body with respect to the main-body, and a sub-body opening and closing drive unit for automatically opening or closing the sub-body by activating a sub-body drive motor, under control of a control unit. The method includes the steps of taking a measurement of an amount of motor driving current applied to the sub-body drive motor when there is an activation of the sub-body opening and closing drive unit to drive the sub-body drive motor for opening or closing the sub-body in compliance with a user&#39;s selection to automatic opening or closing by a switch, and of discontinuing to drive the sub-body drive motor when the measured amount of motor driving current is larger than a predetermined current threshold value and the sensor means detects either a fully open status or a fully closed status of the sub-body. 
     Preferably, the measurement of the motor driving current is carried out in a period of several tens of milliseconds. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: 
         FIG. 1A  is a perspective view illustrating a foldable mobile terminal according to a preferred embodiment of the present invention with its sub-body folded; 
         FIG. 1B  is a perspective view illustrating the foldable mobile terminal according to a preferred embodiment of the present invention with the sub-body unfolded; 
         FIG. 2  is a schematic bock diagram illustrating electrical construction of the foldable mobile terminal according to a preferred embodiment of the present invention; 
         FIG. 3  is a more detailed schematic bock diagram of a sub-body opening and closing control assembly (drive unit) of the foldable mobile terminal according to a preferred embodiment of the present invention; 
         FIG. 4  is a perspective view illustrating a sensible range of an opening sensor upon opening of a sub-body in the foldable mobile terminal according to a preferred embodiment of the present invention; 
         FIG. 5  is a flow chart illustrating a control procedure for automatically opening and closing a sub-body in the foldable mobile terminal according to a preferred embodiment of the present invention; and 
         FIG. 6  is a graphic diagram illustrating stopping positions of a sub-body upon its opening/closing in the foldable mobile terminal according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Like reference numerals are intended to represent like components. 
       FIG. 1A  shows a perspective view of a folder-type mobile terminal  100  with its sub-body folded onto a main-body, while  FIG. 1B  shows a like perspective view of the folder-type mobile terminal with the sub-body unfolded from the main-body. Referring now to  FIGS. 1A and 1B , the folder-type (foldable) mobile terminal  100  includes a main body  110  having an upper casing frame  111  and a lower casing frame  112 , and a sub-body  120  for protecting a keypad  160  mounted on the main body  110 . An opening/closing drive unit  10  for opening or closing the sub-body  120  automatically or manually, as per a user&#39;s selection, is disposed in an upper side of the main-body  110 . Further, the main body  110  is provided with an antenna device  130  mounted on a selected upper edge. The sub-body  120  coupled at its lower end to the main body  110  has an earpiece  140  preferably disposed on its upper part, and an LCD module  150  for a display internally disposed at the lower part of the earpiece  140 . The main body  110  is provided with a keypad  160  and a microphone  170  mounted thereon. Further, an automatic folder opening/closing switch  180  for opening or closing the sub-body  120  is provided to a selected side end of the main-body  110 . The opening/closing drive unit  10  drives to open or close the sub-body  120  on the main-body  110  as a user selects a desired folder operation, either automatic or manual, by means of the automatic folder opening/closing switch  180 . An opening sensor and a closing sensor used for sensing full opening and full closing of the sub-body are respectively disposed in a location indicated by a reference numeral  235  or preferably in its vicinity on the opening/closing drive unit  10  of the main-body  110 . 
     Referring now to  FIG. 2 , a schematic electrical diagram of the foldable mobile terminal  100  according to a preferred embodiment of the present invention is described in more detail. First, a control unit  200  serves to direct and perform overall control operations of the mobile terminal  100 . A radio unit  202  coupled to the control unit  200  serves to control transmitting and reception of voice data, as well as various communication control data, through an antenna ANT under control of the control unit. A voice processing unit  204  serves to convert the voice data received from the radio unit  202  to audible sound through a speaker SPK, and it also serves to convert a voice signal received from a microphone MIC to radio data so that the converted radio data is provided to the radio unit  202  for transmission, under the control of the control unit  200 . A key input unit  206  connected to the control unit  200  is designed with a set of numeral keys, character keys, and various function keys disposed on a keypad  160 , as shown in  FIGS. 1A and 1B . An automatic folder opening/closing switch  180  is arranged on a one side of the main-body  110 . The key input unit  206  supplies to the control unit  200  a respective key data corresponding to a key depressed by a user of the mobile terminal  100 . A display unit  208  serves to display thereon various messages for a user under control of the control unit  200 . A memory unit  230  connected the control unit  200  is preferably designed to have a program memory for storing a set of system operating programs and control data provided by a manufacturer, required to control the entire functions and operations of the mobile terminal  100 , and a data memory for storing various user data temporarily generated during a use of the mobile terminal  100  by a user or upon a system control. The opening/closing drive unit  10  of  FIGS. 1 and 2  includes a motor drive unit  232 , an opening sensor  236 , a closing sensor  238 , a sub-body open/close motor  234  and a current sensor  240 . 
     Referring to  FIG. 3 , a more detailed schematic bock diagram of a sub-body opening and closing drive unit of the foldable mobile terminal according to a preferred embodiment of the present invention is explained. Further,  FIG. 4  illustrates a sensible range  400  of the opening sensor  236  upon opening of the sub-body  120  in the foldable mobile terminal  100 , and the arrangement of the opening sensor  236  and the closing sensor  238  according to a preferred embodiment of the present invention. The motor drive unit  232  receives electric power from a battery of the mobile terminal and serves to drive the sub-body open/close motor  234  positioned inside a hinge  310  coupled with one end of the sub-body  120  in a clockwise or counterclockwise direction under the control of the control unit  200 . A magnet  300  for the opening sensor  236  is mounted onto a peripheral end of the hinge  310  of the sub-body opening/closing drive unit  10 , and the opening sensor  236  is arranged beneath one side of a printed circuit board  410  adjacent to the hinge  310 , the printed circuit board being inserted inside the main-body  110 . Another magnet  302  for the closing sensor  238  is mounted on an inner surface of an upper plate of the sub-body  120 , so that the magnet  302  is placed in contact with the closing sensor  238  in a closed position of the sub-body  120 , in which the closing sensor  238  is disposed on an upper side of the printed circuit board  410 , spaced apart from the hinge  310 . Accordingly, when the sub-body  120  is fully open, the opening sensor  236  is located in a closely adjacent position to the magnet  300  for the opening sensor  236 , as shown in  FIG. 4 , thereby outputting an open sensing signal corresponding to a fully open status of the sub-body  120 . However, when the sub-body  120  is fully closed onto the main-body  110 , the closing sensor  238  is located in a closely adjacent position to the magnet  302  for the closing sensor  238 , thereby outputting a closing sensing signal corresponding to a fully closed status of the sub-body  120 , to the control unit  200 . The opening sensor  236  and the closing sensor  238  are preferably of a kind of hall sensor. The sub-body opening and closing drive unit  10  is provided with a current sensor  240 , which senses a motor drive current applied to the sub-body open/close motor  234  from the motor drive unit  232  and supplies the sensed current to the control unit  200 . 
     Referring to  FIG. 4 , a sensible range  400  of the opening sensor  236  upon opening of the sub-body out of the main-body in the foldable mobile terminal is shown. Within this range, the opening sensor  236  can sense the magnet  300  correctly, but beyond this range the opening sensor  236  cannot sense the magnet  300  accurately. Existence of such a sensible range  400  is apt to mean that the control unit  200  cannot make an accurate control of fully open position of the sub-body  120 . Although  FIG. 4  illustrates the sensible range of the opening sensor  236  only upon opening of the sub-body  120 , it should be noted that a sensible range of the closing sensor  238  also exists likewise. 
     Referring now to  FIG. 5 , a flow chart of a control procedure for automatically opening and closing the sub-body  120  in the foldable mobile terminal  100  according to a preferred embodiment of the present invention is shown. The control unit  200  performs the control procedure to make a precise control of stopping position of opening and closing of the sub-body  120 . Hereinafter, operation of the control procedure of the present invention will be described in more detail with reference to the aforementioned figures. 
     Assuming that a user of the foldable mobile terminal initially performs a manipulation of automatic opening/closing of a sub-body  120  by depressing an automatic folder opening/closing switch  180 , the control unit  200  receives predetermined key data corresponding to the depressed switch  180 , so that it is recognized as a control of automatic opening or closing of the sub-body  120  in step  500  as shown in  FIG. 5 . Then, in step  502 , the control unit  200  performs a motor drive control for a given time so as to open or close the sub-body  120  from or onto the main-body  110 . That is, the control unit  200  makes a control of the motor drive  232  to have the sub-body open/close motor  234  rotate either in a clockwise direction to open the sub-body or in a counterclockwise direction to close the sub-body. In step  504 , the control unit  200  periodically makes a measurement of an amount of motor driving current sensed by the current sensor  240  by a predetermined period, for instance, every 30 milliseconds (msec), and then the amount of motor driving current is converted into a corresponding value of current code by an analog-to-digital converter (not shown) internally installed within the control unit  200  so that the converted current value can be further processed. 
     Referring now to  FIG. 6 , stopping positions of the sub-body  120  upon its opening/closing in the foldable mobile terminal according to a preferred embodiment of the present invention are graphically shown. In  FIG. 6 , a curved line A represents a profile of the current code values measured by the control unit  200  in every 30 msec period, a threshold value THR represents a given reference value used for anticipating a status of motor operation, and a reference numeral  602  represents a sensing range capable of detecting the magnet  300  by the opening sensor  236  and the closing sensor  238 . 
     Meanwhile, in step  506 , the control unit  200  makes a control to determine whether the measured current code value is more than a predetermined current threshold value THR, in which step the current code values more than this current threshold value THR will stand for an overloaded state of the sub-body open/close motor  234 . Such an overload status on the motor  234  is probably caused by a physical obstruction preventing a smooth movement during opening or closing of the sub-body  120 , a fully open situation of the sub-body  120 , or a fully closed situation thereof Hence, if the measured current code is larger than the predetermined current threshold value THR, then the control proceeds to step  508  to determine whether the opening sensor  236  or the closing sensor  238  have sensed the magnet  300 . In the step  508 , when the opening sensor  236  or the closing sensor  238  have sensed the magnet  300 , that is to say, when the previous two decision steps  506  and  508  are answered “YES”, then the control of the control unit  200  proceeds to step  514  to stop driving the sub-body open/close motor  234  immediately. 
     A position  604  as seen in  FIG. 6  represents the very position of meeting all the decision conditions (for instance, answered “YES”) on the above two steps  506  and  508 . It should be noted that this position  604  will not be formed in a certain range but at one point of location, as illustrated in  FIG. 6 . This leads to a conclusion that an opening or closing position of the sub-body  120  can be controlled properly and precisely. 
     In step  508 , when the opening sensor  236  or the closing sensor  238  have not sensed the magnet  300 , that is, answered “NO”, then the control unit  200  proceeds to step  510  to increase a number of motor driving repetition by “1” from an initial value “0” for driving the sub-body open/close motor  234  further. This situation usually occurs when a smooth movement of the sub-body is physically interfered with by any outside obstruction during its opening or closing. Preferably, a counter to count the number of motor driving repetitions is provided to the control unit  200  or in association with the control unit  200  internally or externally. Then, the control unit  200  determines in step  512  whether or not the number of motor driving repetitions counted reaches a predetermined natural number “N”, so that if the counted number has not still reached the number “N”, then the control proceeds to the previous step  504  to repeat the aforementioned similar operations. However, if the counted number has reached the number “N”, then the control proceeds to the step  514  to discontinue to drive the sub-body open/close motor  234  immediately. 
     As understood from the foregoing description, the present invention will not only achieve a very effective opening and/or closing operation of the sub-body in the foldable mobile communication terminal, but also a fully opening or closing position of the sub-body could be controlled in more safe and accurate manner. 
     While the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications in form and detail may be made therein and equivalents may be substituted for elements thereof, without departing from the spirit and scope of the invention as defined by the appended claims.

Summary:
Disclosed are an apparatus and a method for controlling a correct position of opening and closing a sub-body (folder) in an automatic foldable mobile communication terminal. A sensor means is arranged in one end of a main-body and the sub-body, for detecting a fully open status or a fully closed status of the sub-body. A sub-body opening and closing drive unit opens or closes the sub-body by activating a drive motor. A current sensing unit is coupled to a control unit for sensing an amount of motor drive current applied to the sub-body drive motor. The control unit measures the motor drive current from the current sensing unit upon an enabling of an automatic opening or closing operation of the sub-body, and then discontinues to drive the sub-body drive motor when the measured amount of the motor drive current is larger than a predetermined current threshold and the sensor means senses either one of a fully open status or a fully closed status.