Patent Publication Number: US-8982000-B2

Title: Watch type mobile terminal and antenna thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Pursuant to 35 U.S.C. §119, this application claims the benefit of Korean Application No. 10-2009-0064669, filed on Jul. 15, 2009, the contents of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a watch type mobile terminal that can be put on a human body such as a user&#39;s wrist, arm, and so on. 
     2. Description of the Related Art 
     A watch type mobile terminal is a device that can be carried around and has one or more functions such as voice and video call communication, inputting and outputting information, storing data, and the like. 
     As such functions become more diversified, the watch type mobile terminal can support more complicated functions such as capturing images or video, reproducing music or video files, playing games, receiving broadcast signals, and the like. By comprehensively and collectively implementing such functions, the watch type mobile terminal may be embodied in the form of a multimedia player or device. 
     In order to implement various functions of such multimedia players or devices, the multimedia player requires sufficient support in terms of hardware or software, for which numerous attempts are being made and implemented. For example, a user interface allowing users to easily and conveniently search for and select one or more functions is provided. 
     Also, as watch type mobile terminals are considered a personal mobile object that can express users&#39; personality, various designs are required. Such demand on designs may include a structural alteration and modification allowing users to conveniently use watch type mobile terminal, and as one of such structural alteration and modification, a watch-type watch type mobile terminal that can be put on the user&#39;s wrist to use can be considered. Because a watch type mobile terminal serves as a clock as well as a watch type mobile terminal, a reduction in thickness and size and simplified design are critical for designing a watch-type watch type mobile terminal. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to address the above-noted and other problems. 
     Another object of the present invention is to provide a watch type mobile terminal that can be put on the user&#39;s wrist and includes an antenna disposed within a case having a great mechanical restriction, thus improving an external appearance and accomplishing good radio performance. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention provides in one aspect a watch type mobile terminal including: a case whose both ends are connected by a band and an antenna installed in the case, wherein the antenna includes: a first conductor disposed at an inner side of the case and formed such that the first conductor can be connected to a signal feeding portion; and a second conductor disposed to be separated from the first conductor such that the second conductor is electrically coupled with the first conductor and formed such that the second conductor can be connected to a ground feeding unit. 
     The case may include: a first conductive case forming a surrounding configuration of a window; a second dielectric case assembled to a lower portion of the first case and having an accommodation space part for accommodating a component therein; and a third conductive case assembled to a lower portion of the second case and forming a ground. 
     The second case may include a slope side, and the antenna may be disposed on an inner surface of the slope side. 
     The antenna may be formed to have a plate form attached to a dielectric carrier. 
     The first conductor may include a first end portion formed to be convex, and the second conductor may include a second end portion disposed to be separated from the first end portion with a certain gap therebetween and formed to be protruded. 
     The first case may be formed to be inserted in the second case. 
     The watch type mobile terminal may further include: a first ground extending part extending a ground at an inner side of the second case to the first case. 
     The ground extending part may include a conductive layer disposed to be adjacent to the first case at a certain interval at an inner side of the second case. 
     The first ground extending part may be disposed on the opposite side of the side of the second case where the antenna is disposed. 
     A touch pad may be formed at an inner side of an upper end of the first case to detect a touch, and a controller of the touch pad may be disposed to be adjacent to the side of the second case where the first ground extending part is disposed. 
     The first ground extending part may be directly connected to the third case by a flexible printed circuit board (FPCB). 
     The watch type mobile terminal may further include: a second ground extending part extending a ground to the band. 
     The second ground part may be implemented in the form of a flexible conductive tape inserted to be parallel to the band. 
     The band may include: a support member supporting a pin; and a connection member disposed at the inner side of the support member and connected to the second ground extending part. 
     The connection member may include a protrusion such that the protrusion can be brought into contact with the third case when the band is assembled, and the third case may include an accommodation recess accommodating the protrusion therein. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention provides in another aspect a watch type mobile terminal including: a first conductive case forming a surrounding configuration of a window; a second dielectric case assembled to a lower portion of the first case and having an accommodation space part for accommodating a component therein; a third conductive case assembled to a lower portion of the second case and forming a ground; an antenna installed at an inner side of the second case; and a ground extending part extending a ground of the antenna to the first case. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a schematic block diagram of a watch type mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 2  is a top perspective view of the watch type mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 3  is an exploded perspective view of the watch type mobile terminal of  FIG. 2 ; 
         FIG. 4  is a perspective view of an antenna according to an exemplary embodiment of the present invention; 
         FIG. 5  is an exploded perspective view of the watch type mobile terminal viewed in a different direction; 
         FIG. 6  is a conceptual sectional view of a terminal main body according to an exemplary embodiment of the present invention; 
         FIG. 7  is a conceptual view for explaining the principle of increasing the length of a ground; 
         FIG. 8  is a sectional view showing a detailed configuration of the watch type mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 9  is a perspective view of the watch type mobile terminal including a second ground extending part mounted on a band; 
         FIG. 10  is a conceptual view showing the principle of the second ground extending part illustrated in  FIG. 9 ; 
         FIG. 11  is a perspective view showing a connection structure of the band for connecting the second ground extending part according to an exemplary embodiment of the present invention; and 
         FIG. 12  is a sectional view showing a connection structure of the band of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A watch type mobile terminal according to exemplary embodiments of the present invention will now be described in detail. In the following description, usage of suffixes such as ‘module’, ‘part’ or ‘unit’ used for referring to elements is given merely to facilitate explanation of the present invention, without having any significant meaning by itself. 
     The watch type mobile terminal described in the present invention may include mobile phones, smart phones, notebook computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PMPs (Portable Multimedia Player), navigation devices, and the like. 
       FIG. 1  is a block diagram of a watch type mobile terminal according to an embodiment of the present invention. 
     The watch type mobile terminal  100  may include a wireless communication unit  110 , an A/V (Audio/Video) input unit  120 , a user input unit  130 , a sensing unit  140 , an output unit  150 , a memory  160 , an interface unit  170 , a controller  180 , and a power supply unit  190 , etc.  FIG. 1  shows the watch type mobile terminal as having various components, but it should be understood that implementing all of the illustrated components is not a requirement. Greater or fewer components may alternatively be implemented. 
     The elements of the watch type mobile terminal will be described in detail as follows. 
     The wireless communication unit  110  typically includes one or more components allowing radio communication between the watch type mobile terminal  100  and a wireless communication system or a network in which the watch type mobile terminal is located. For example, the wireless communication unit may include at least one of a broadcast receiving module  111 , a mobile communication module  112 , a wireless Internet module  113 , a short-range communication module  114 , and a location information module  115 . 
     The broadcast receiving module  111  receives broadcast signals and/or broadcast associated information from an external broadcast management server (or other network entity) via a broadcast channel. The broadcast channel may include a satellite channel and/or a terrestrial channel. The broadcast management server may be a server that generates and transmits a broadcast signal and/or broadcast associated information or a server that receives a previously generated broadcast signal and/or broadcast associated information and transmits the same to a terminal. The broadcast signal may include a TV broadcast signal, a radio broadcast signal, a data broadcast signal, and the like. Also, the broadcast signal may further include a broadcast signal combined with a TV or radio broadcast signal. The broadcast associated information may refer to information associated with a broadcast channel, a broadcast program or a broadcast service provider. The broadcast associated information may also be provided via a mobile communication network and, in this case, the broadcast associated information may be received by the mobile communication module  112 . 
     The broadcast signal may exist in various forms. For example, it may exist in the form of an electronic program guide (EPG) of digital multimedia broadcasting (DMB), electronic service guide (ESG) of digital video broadcast-handheld (DVB-H), and the like. 
     The broadcast receiving module  111  may be configured to receive signals broadcast by using various types of broadcast systems. In particular, the broadcast receiving module  111  may receive a digital broadcast by using a digital broadcast system such as multimedia broadcasting-terrestrial (DMB-T), digital multimedia broadcasting-satellite (DMB-S), digital video broadcast-handheld (DVB-H), the data broadcasting system known as media forward link only (MediaFLO®), integrated services digital broadcast-terrestrial (ISDB-T), etc. The broadcast receiving module  111  may be configured to be suitable for every broadcast system that provides a broadcast signal as well as the above-mentioned digital broadcast systems. 
     Broadcast signals and/or broadcast-associated information received via the broadcast receiving module  111  may be stored in the memory  160  (or anther type of storage medium). 
     The mobile communication module  112  transmits and/or receives radio signals to and/or from at least one of a base station (e.g., access point, Node B, etc.), an external terminal (e.g., other user devices) and a server (or other network entities). Such radio signals may include a voice call signal, a video call signal or various types of data according to text and/or multimedia message transmission and/or reception. 
     The wireless Internet module  113  supports wireless Internet access for the watch type mobile terminal. This module may be internally or externally coupled to the terminal. The wireless Internet access technique implemented may include a WLAN (Wireless LAN) (Wi-Fi), Wibro (Wireless broadband), Wimax (World Interoperability for Microwave Access), HSDPA (High Speed Downlink Packet Access), or the like. 
     The short-range communication module  114  is a module for supporting short range communications. Some examples of short-range communication technology include Bluetooth™, Radio Frequency IDentification (RFID), Infrared Data Association (IrDA), Ultra-WideBand (UWB), ZigBee™, and the like. 
     The location information module  115  is a module for checking or acquiring a location (or position) of the watch type mobile terminal. A typical example of the location information module is a GPS (Global Positioning System). According to the current technology, the GPS module  115  calculates distance information from three or more satellites and accurate time information and applies trigonometry to the calculated information to thereby accurately calculate three-dimensional current location information according to latitude, longitude, and altitude. Currently, a method for calculating location and time information by using three satellites and correcting an error of the calculated location and time information by using another one satellite has been provided. In addition, the GPS module  115  can calculate speed information by continuously calculating the current location in real time. 
     The A/V input unit  120  is configured to receive an audio or video signal. The A/V input unit  120  may include a camera  121  (or other image capture device) and a microphone  122  (or other sound pick-up device). The camera  121  processes image data of still pictures or video obtained by an image capture device in a video capturing mode or an image capturing mode. The processed image frames may be displayed on a display unit  151  (or other visual output device). 
     The image frames processed by the camera  121  may be stored in the memory  160  (or other storage medium) or transmitted via the wireless communication unit  110 . Two or more cameras  121  may be provided according to the configuration of the watch type mobile terminal. 
     The microphone  122  may receive sounds (audible data) via a microphone (or the like) in a phone call mode, a recording mode, a voice recognition mode, and the like, and can process such sounds into audio data. The processed audio (voice) data may be converted for output into a format transmittable to a mobile communication base station (or other network entity) via the mobile communication module  112  in case of the phone call mode. The microphone  122  may implement various types of noise canceling (or suppression) algorithms to cancel (or suppress) noise or interference generated in the course of receiving and transmitting audio signals. 
     The user input unit  130  (or other user input device) may generate input data from commands entered by a user to control various operations of the watch type mobile terminal. The user input unit  130  may include a keypad, a dome switch, a touch pad (e.g., a touch sensitive member that detects changes in resistance, pressure, capacitance, etc. due to being contacted) a jog wheel, a jog switch, and the like. 
     The sensing unit  140  (or other detection means) detects a current status (or state) of the watch type mobile terminal  100  such as an opened or closed state of the watch type mobile terminal  100 , a location of the watch type mobile terminal  100 , the presence or absence of user contact with the watch type mobile terminal  100  (i.e., touch inputs), the orientation of the watch type mobile terminal  100 , an acceleration or deceleration movement and direction of the watch type mobile terminal  100 , etc., and generates commands or signals for controlling the operation of the watch type mobile terminal  100 . For example, when the watch type mobile terminal  100  is implemented as a slide type mobile phone, the sensing unit  140  may sense whether the slide phone is opened or closed. In addition, the sensing unit  140  can detect whether or not the power supply unit  190  supplies power or whether or not the interface unit  170  is coupled with an external device. The sensing unit  140  may include a proximity sensor  141 . The proximity sensor  141  will be described in relation to a touch screen later. 
     The interface unit  170  serves as an interface by which at least one external device may be connected with the watch type mobile terminal  100 . For example, the external devices may include wired or wireless headset ports, an external power supply ports, wired or wireless data ports, memory card ports, ports for connecting a device having an identification module, audio input/output (I/O) ports, video I/O ports, earphone ports, or the like. 
     The identification module may be a chip that stores various information for authenticating user&#39;s authority for using the watch type mobile terminal  100  and may include a user identity module (UIM), a subscriber identity module (SIM) a universal subscriber identity module (USIM), and the like. In addition, the device having the identification module (referred to as the ‘identifying device’, hereinafter) may take the form of a smart card. Accordingly, the identifying device may be connected with the terminal  100  via a port or other connection means. The interface unit  170  may be used to receive inputs (e.g., data, information, power, etc.) from an external device and transfer the received inputs to one or more elements within the watch type mobile terminal  100  or may be used to transfer data between the watch type mobile terminal and an external device. 
     In addition, when the watch type mobile terminal  100  is connected with an external cradle, the interface unit  170  may serve as a conduit to allow power from the cradle to be supplied therethrough to the watch type mobile terminal  100  or may serve as a conduit to allow various command signals inputted from the cradle to be transferred to the watch type mobile terminal therethrough. Various command signals or power inputted from the cradle may be operated as a signal for recognizing that the watch type mobile terminal is accurately mounted on the cradle. 
     The output unit  150  is configured to provide outputs in a visual, audible, and/or tactile manner (e.g., audio signal, video signal, alarm signal, vibration signal, etc.). The output unit  150  may include the display unit  151 , an audio output module  152 , an alarm unit  153 , and the like. 
     The display unit  151  may display information processed in the watch type mobile terminal  100 . For example, when the watch type mobile terminal  100  is in a phone call mode, the display unit  151  may display a User Interface (UI) or a Graphic User Interface (GUI) associated with a call or other communication (such as text messaging, multimedia file downloading, etc.). When the watch type mobile terminal  100  is in a video call mode or image capturing mode, the display unit  151  may display a captured image and/or received image, a UI or GUI that shows videos or images and functions related thereto, and the like. 
     Meanwhile, when the display unit  151  and the touch pad are overlaid in a layered manner to form a touch screen, the display unit  151  may function as both an input device and an output device. The display unit  151  may include at least one of a Liquid Crystal Display (LCD), a Thin Film Transistor-LCD (TFT-LCD), an Organic Light Emitting Diode (OLED) display, a flexible display, a three-dimensional (3D) display, or the like. 
     The proximity sensor  141  may be disposed within or near the touch screen. The proximity sensor  141  is a sensor for detecting the presence or absence of an object relative to a certain detection surface or an object that exists nearby by using the force of electromagnetism or infrared rays without a physical contact. Without the proximity sensor  141 , if the touch screen is an electrostatic type, the approach of a pointer (stylus) can be detected based on a change in a field according to the approach of the pointer. 
     The audio output module  152  may convert and output as sound audio data received from the wireless communication unit  110  or stored in the memory unit  160  in a call signal reception mode, a call mode, a record mode, a voice recognition mode, a broadcast reception mode, and the like. Also, the audio output module  152  may provide audible outputs related to a particular function performed by the watch type mobile terminal  100  (e.g., a call signal reception sound, a message reception sound, etc.). The audio output module  152  may include a speaker, a buzzer, or other sound generating device. 
     The alarm unit  153  (or other type of user notification means) may provide outputs to inform about the occurrence of an event of the watch type mobile terminal  100 . Typical events may include call reception, message reception, key signal inputs, a touch input etc. In addition to audio or video outputs, the alarm unit  153  may provide outputs in a different manner to inform about the occurrence of an event. For example, the alarm unit  153  may provide an output in the form of vibrations (or other tactile or sensible outputs). When a call, a message, or some other incoming communication is received, the alarm unit  153  may provide tactile outputs (i.e., vibrations) to inform the user thereof. By providing such tactile outputs, the user can recognize the occurrence of various events even if his mobile phone is in the user&#39;s pocket. Outputs informing about the occurrence of an event may be also provided via the display unit  151  or the audio output module  152 . 
     The memory unit  160  may store software programs or the like used for the processing and controlling operations performed by the controller  180 , or may temporarily store data (e.g., a phonebook, messages, still images, video, etc.) that have been outputted or which are to be outputted. In addition, the memory unit  160  may store data regarding various patterns of vibrations and sounds outputted when a touch is applied onto the touch screen. 
     The memory unit  160  may include at least one type of storage medium including a Flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory, etc), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read-Only Memory (ROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Programmable Read-Only Memory (PROM), a magnetic memory, a magnetic disk, an optical disk, and the like. Also, the watch type mobile terminal  100  may cooperate with a network storage device that performs the storage function of the memory unit  160  over a network connection. 
     The controller  180  typically controls the general operations of the watch type mobile terminal. For example, the controller  180  performs controlling and processing associated with voice calls, data communications, video calls, and the like. In addition, the controller  180  may include a multimedia module  181  for reproducing (or playing back) multimedia data. The multimedia module  181  may be configured within the controller  180  or may be configured to be separate from the controller  180 . 
     The controller  180  may perform a pattern recognition processing to recognize a handwriting input or a picture drawing input performed on the touch screen as characters or images. 
     The power supply unit  190  receives external power (via a power cable connection) or internal power (via a battery of the watch type mobile terminal) and supplies appropriate power required for operating respective elements and components under the control of the controller  180 . 
     The watch type mobile terminal according to an exemplary embodiment of the present invention has been described in view of the components according to the function of the watch type mobile terminal. Hereinafter, the watch type mobile terminal will be described in the aspect of mechanical components. 
       FIG. 2  is a top perspective view of the watch type mobile terminal according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 2 , the watch type mobile terminal  100  includes a terminal body  101  disposed such that the display unit  151  is exposed from an upper surface thereof, and both ends of the terminal body  101  are connected by a band  107  formed to allow the user to put the watch type mobile terminal  100  on his body such as the wrist arm, and so one. The terminal body  101  may include devices for various supplementary functions including a mobile communication module allowing for communication with a base station, a network, a server device, an external device, and the like, in a communication network. 
     The terminal body  101  includes a plurality of cases forming an external appearance. In  FIG. 2 , a first case  103  and a second case  104  are shown to be exposed. 
     A light-transmissive window  102  is installed on upper surface of the first case  103  such that the display unit  151  is seen therethrough. The audio output module  152  for outputting a sound and a camera device  121  for capturing an image are disposed at one side of the display unit  151  within the window  102 . 
     The display unit  151  includes a liquid crystal display (LCD), an organic light emitting diode (OLED) module, an e-paper, and the like, which visually displays information. The display unit  151  may include a touch pad allowing for an input in a tactile manner. Accordingly, when a touch is applied to a portion on the window  102 , content corresponding to the touched position is inputted. The content inputted in a tactile manner may be characters, numbers, a menu item that can be instructed or designated in various modes, and the like. A structure for increasing visibility of the display unit  151  at a bright area may be included at an upper portion of the display unit  151 . 
     The audio output module  152  may be a receiver in the aspect that it outputs a reception sound, and may be formed as a loud speaker for providing a louder sound in outputting a notification sound of a system or in a speaker phone mode or a multimedia reproduction mode, and the like. 
     The camera device  121  may be configured to capture a still image or video of a subject and may be used for taken an image of the user himself during video call communication. 
     A side button  131  for a manipulation is disposed on the side of the terminal body  101 . The side button  131  may be generally called a manipulation unit and receives a command for controlling the operation of the watch type mobile terminal. Various methods can be employed for the side button  131  so long as it can operate by the user in a tactile manner. Convent inputted by the side button  131  may be variably set. For example, commands such as turning on or off power, controlling the camera device  121 , adjusting the size of a sound outputted from the audio output module  152 , changing of the display unit  151  to a touch recognition mode, and the like, may be received through the side button  131 . 
     The band  107  may be formed to be flexible so as to be easily put on the user&#39;s body. For example, the band  107  may be made of leather, rubber, plastic, and the like, and may be formed to have a multi-layered structure by stacking several unit layers. 
     A fastener  108  may be provided to the band  107 . The fastener  108  may be implemented as a buckle, a snap-fit hook, or Velcro™, etc., and may have an elastic portion or may be made of an elastic material. The fastener  108  as shown in  FIG. 2  is a buckle type fastener. 
       FIG. 3  is an exploded perspective view of the watch type mobile terminal of  FIG. 2 . As shown in  FIG. 3 , the cases constituting the external appearance of the terminal body  101  include a first case  103  forming a peripheral configuration of the window  102 , and second and third cases  104  and  105  sequentially assembled to a lower portion of the first case  103 . 
     The second case  104  includes an accommodation space part for mounting various components, and a mounting recess  104   b  is formed on an upper end of the second case  104  to allow the first case  103  to be insertedly mounted therein. 
     The first case  103  is a part that can be easily in contact with an external object of the watch type mobile terminal  100  along with the window  102 , so it may be made of a metal material so as to minimize its abrasion or scratch. In addition, the first case  103  may be made of a conductive material in order to extend a ground of the antenna  200  (to be described). Also, the first case  103  may be implemented as an ‘ornament’ present on the surface of the ‘case’, as well as its role as a substantial ‘case’. 
     The second case  104  is made of a dielectric material so as to smoothly induce radiation of the antenna  200 . The second case  104  may be made of a resin or the like in order to facilitate formation of an intricate internal shape. 
     Externally, the second case  104  includes a slope side  104   a  forming a smooth side appearance of the window  102 , and the antenna  200  is disposed on an inner surface of the slope side  104   a . Thus, the antenna  200  is positioned such that it does not overlap with the first case  103  and disposed at a slope angle, maintaining a certain distance from the third case  105 , so the radiation of radio frequency energy of the antenna  200  can be less restricted. 
     The third case  105  assembled to the lower portion of the second case  104  is formed to be conductive to form a main ground of the antenna  200 . The third case  105  may include a cover  106  detachable to allow a SIM card or the like to be inserted therein. 
       FIG. 4  is a perspective view of an antenna according to an exemplary embodiment of the present invention. As shown in  FIG. 4 , the antenna  200  is illustrated to have a plate shape attached to a dielectric carrier  201 . The carrier  201  is formed to be parallel to the inner side of the slope side  104   a  so as to be easily disposed on the inner surface of the slope side  104   a.    
     The antenna  200  includes a first conductor  210  formed to be connected with a signal feeding part  211  and a second conductor  220  disposed to be separated from the first conductor  210  such that it can be electrically coupled with the first conductor  210 . 
     The first conductor  210  has a certain pattern to have a length suitable for a resonance frequency band. The first conductor  210  is connected to the signal feeding part  211 , and the signal feeding part  211  is formed to be brought into contact with a contact member  262  (See  FIG. 8 ) formed on a circuit board. The contact member  262  may be formed as an elastic spring having a channel-like shape and can be attached to the circuit board through welding. Conversely, the signal feeding part  211  itself may be formed as an elastic spring type. 
     The second conductor  220  is formed such that it can be electrically coupled with the first conductor  210  in order to extend a high bandwidth. The second conductor  220  is connected with a ground feeding part  221  so as to be connected to a ground of the watch type mobile terminal  100 . In detail, the ground feeding part  221  is connected with a ground (not shown) of the display unit  151 , and the ground of the display unit  151  is sequentially connected with a conductive layer  192  covering the battery  190  and a shield can  265  surrounding the circuit board  260 . 
     The first conductor  210  may be formed to be resonated at a multi-band including GSM800˜900, DCS1600˜1800, PCS1600˜1900, W2100, and the like. The second conductor  220  serves to generate coupling at a high band to extend the bandwidth of the high band. 
     For example, as shown in  FIG. 4 , the first conductor  210  includes a first end portion  212  formed to be convex and separated from the first end portion  212  with a certain gap therebetween. The electrical coupling structure can effectively solves a problem of insufficient space for installing the antenna required for satisfying all the bands as mentioned above when the antenna is installed at the inner side of the watch type mobile terminal. 
       FIG. 5  is an exploded perspective view of the watch type mobile terminal of  FIG. 2  viewed in a different direction. 
     As shown in  FIG. 5 , the watch type mobile terminal  100  illustrated in  FIG. 5  includes a first ground extending part  230  for extending a ground of the antenna  200  to the first case  103 . 
     The first ground extending part  230  includes a conductive layer  231  disposed to be parallel to the first case  103  at an inner side of the second case  104 . Thus, as an electrical coupling is generated between the first case  103  and the conductive layer  231 , a ground length of the antenna  200  can be lengthened. The conductive layer  231  may be formed in the form of a conductive gasket or a tape. 
     This principle will now be described with reference to  FIGS. 6 and 7 .  FIG. 6  is a conceptual sectional view of a terminal main body according to an exemplary embodiment of the present invention, and  FIG. 7  is a conceptual view for explaining the principle of increasing the length of a ground. 
     As shown in  FIG. 6 , a ground feeding part  221  connected with the antenna  200  is connected with the third case  105  forming a ground, and the antenna  200  may be disposed to be coupled with the first case  103  with a certain gap (e.g., 0.5 mm as the thickness of the second case) therebetween. The first case  103  is coupled with the third case  105  at the opposite side of the antenna  200 . 
     As a result, the ground length is limited to a length L 1  of the third case  105  in the section form as shown in  FIG. 7A , but as shown in  FIG. 7B , because of the electrical coupling between the first case  103  and the third case  105 , an effect that a ground length L 2  is equivalent to the sum of the length of the third case  105  an the length of the first case  103  can be obtained. Thus, radio performance of the antenna  200  can be improved and is less affected by a human body (also called a ‘hand effect’). 
     The conductive layer  231  and the first ground extending part  230  are disposed at the opposite side of the slope side  104   a  of the second case  104  where the antenna  200  is disposed. In particular, because a controller  105  of the touch pad is disposed in the space where the conductive layer  231  is disposed, mutual influence between the touch pad and the antenna  200  can be reduced. 
     The first ground extending part  230  is directly connected to the third case  105  by a flexible printed circuit board (FPCB)  232  in order to maximize the ground extension effect. 
       FIG. 8  is a sectional view showing a detailed configuration of the watch type mobile terminal according to an exemplary embodiment of the present invention. As shown in  FIG. 8 , the watch type mobile terminal  100  includes components assembly mounted in an accommodation space formed by the second case  104  and the third case  105 . The components assembly includes a circuit board  260 , a battery  190 , a display unit  151 , and an audio output unit  152 . 
     A socket  261  is formed on a lower surface of the circuit board  260  to mount an SIM card thereon, and a component such as a processor for radio communication, a processor for driving multimedia, or the like, is mounted on an upper surface of the circuit board  260 . The upper surface of the circuit board  260  is covered by the shield can  265 , interrupting an electromagnetic interference. 
     The battery  190  disposed at an upper side of the circuit board  260  is formed such that it can be recharged. The battery  190  receives power from an external source through a terminal exposed from the lower surface of the third case  105  so as to be charged. 
       FIG. 9  is a perspective view of the watch type mobile terminal including a second ground extending part mounted on a band. As shown in  FIG. 9 , the ground limited to the third case  105  can be extended by the second ground extending part  240  inserted to be parallel in the band  107 . 
       FIG. 10  is a conceptual view showing the principle of the second ground extending part illustrated in  FIG. 9 . 
     As shown in  FIG. 10 , it is noted that the length of the ground of the third case  105  extends by the second ground extending part  240  included in the band  107 . A 1/4 λcondition with respect to a low band such as GSM800˜900 can be easily satisfied by the band  107 , and because the second ground extending part  240  added to the band  107  is not exposed, an aesthetic appearance cannot be hampered. 
       FIG. 11  is a perspective view showing a connection structure of the band for connecting the second ground extending part according to an exemplary embodiment of the present invention, and  FIG. 12  is a sectional view showing a connection structure of the band of  FIG. 11 . 
     As shown in  FIGS. 11 and 12 , a support member  109  having a pin hole  252  for supporting a pin and a metal connection member  254  disposed at an inner side of the support member  109  are provided at an end portion of the band  107 . 
     The support member  109  is made of rubber or a plastic material in order to strengthen an adhesive force of the band made of leather or plastic, and the connection member  254  is installed at the inner side of the support member  109  in order to connect the ground of the terminal body  101  to the second ground extending part  240 . 
     In order to prevent a contact force of the connection member  254  from weakening when the band  107  is put on, the connection member  254  includes a protrusion  251  which is brought into contact with the third case  105  when the band  107  is assembled. Also, a receiving recess  105   a  for receiving the protrusion  251  is formed at an end portion of the third case  105 . Thus, when the band  107  is fixed to the second case  104  by a pin, the protrusion of the connection member  254  disposed at the end of the band  107  is received by the accommodation recess  105   a  of the third case  105  so as to be electrically connected constantly. 
     The second ground extending part  240  may be made of a flexible conductive material. Preferably, the second ground extending part  240  may be formed in the form of a conductive tape.  FIG. 12  shows that the second ground extending part  240  is attached to the connection member  254  by a fixing mold  254  inserted into the support member  109  to thereby guarantee an adhesive force with respect to the connection member  250  of the second ground extending part  240 . 
     As described above, the watch type mobile terminal according to exemplary embodiments of the present invention have the following advantages. 
     That is, because the cases having a metal component are positively used to extend the ground, radio performance of the antenna can be improved. 
     The ground of the antenna installed at the inner side of the nonmetal second case extends to the first case, so the first case can become a secondary antenna. The first case can be used as an element for forming an external ornament of the watch type mobile terminal, requirements in a design view or in view of the antenna performance can be easily satisfied. 
     As the exemplary embodiments may be implemented in several forms without departing from the 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 scope as defined in the appended claims. Therefore, various changes and modifications that fall within the scope of the claims, or equivalents of such scope are therefore intended to be embraced by the appended claims.