Abstract:
An electronic device including a first body having a first battery; and a second body having a second battery, the second body being configured to be electrically connected to the first body and separatable from the first body; the first body including: receiving a request for charge of battery from the first body or the second body; retrieving a remaining amount of battery inside the first body and the second body; comparing the battery of the first body and the battery of the second battery on the basis of the retrieved remaining amount of battery; carrying out a charging process for the requested battery indicated by the received request in case that a power source including the not-requested battery satisfies a predetermined requirement as a result of the comparing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-253049, filed on Nov. 4, 2009, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments discussed herein relate to an electronic device and a power source control device. 
         [0004]    2. Description of the Related Art 
         [0005]    Currently, electronic devices such as mobile terminal devices or the like have an increasing range of functions. Some mobile terminal devices can be used to perform, for example, various kinds of information processing operations such as verbal communication, document creation, accessing of websites, sending and receiving of e-mail messages, video reproduction, or the like. In addition, there are electronic devices that take various kinds of modified forms in which the electronic devices can be separated into two parts and used so that users can comfortably use such functions. 
         [0006]    In order for the users to comfortably use the electronic devices, some of the electronic devices, which can be separated and used individually and independently include batteries and operate by consuming the charge of batteries thereof. 
         [0007]    Regarding this, there is known a technique in which two devices, namely, a mobile terminal and a module that can be separated from the mobile terminal, are included, and a power source in the module is charged using a battery in the mobile terminal when the power source in the module is drained (for example, refer to Japanese Unexamined Patent Application Publication No. 2001-231065). 
       SUMMARY 
       [0008]    Embodiments discussed herein are related to an electronic device including a first body having a first battery; and a second body having a second battery, the second body being configured to be electrically connected to the first body and separatable from the first body. 
         [0009]    The first body includes: a receiving unit that receives a charge request from the first body or the second body, the charge request being associated with the first battery or the second battery; a retrieval unit that retrieves a remaining amount of battery charge of the first battery and a remaining amount of charge of the second battery; a comparison unit that compares the remaining amount of battery charge of the first battery and the remaining amount of battery charge of the second battery; a control unit that carries out a charging process for the first battery or second battery associated with the charge request in a case that a power source including the first or second battery not associated with the charge request satisfies a condition based on the comparing. 
         [0010]    The object and advantages of the invention will be realized and attained by the elements and combinations particularly pointed out in the claims. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0012]      FIG. 1  illustrates an electronic device according to a first embodiment; 
           [0013]      FIGS. 2A to 2F  illustrate external appearance of a mobile terminal device according to a second embodiment; 
           [0014]      FIGS. 3A and 3B  illustrate external appearance of the mobile terminal device, which is in a mechanically separated state, according to the second embodiment; 
           [0015]      FIGS. 4A to 4F  illustrate external appearance of an input operation section according to the second embodiment; 
           [0016]      FIGS. 5A to 5F  illustrate external appearance of an information display section according to the second embodiment; 
           [0017]      FIGS. 6A to 6F  illustrate external appearance of the input operation section, which is in a stretched state, according to the second embodiment; 
           [0018]      FIGS. 7A to 7F  illustrate external appearance of the mobile terminal device, which is in a stretched state, according to the second embodiment; 
           [0019]      FIG. 8  illustrates a hardware configuration of the mobile terminal device according to the second embodiment; 
           [0020]      FIG. 9  illustrates a function of the mobile terminal device according to the second embodiment; 
           [0021]      FIG. 10  illustrates a logic circuit for a switching control section according to the second embodiment; 
           [0022]      FIG. 11  illustrates a processing operation performed when the input operation section and the information display section are charged using an adapter connected to the input operation section according to the second embodiment; 
           [0023]      FIG. 12  illustrates a flow of the processing operation performed when the input operation section and the information display section are charged using the adapter connected to the input operation section according to the second embodiment; 
           [0024]      FIG. 13  illustrates a battery power supply processing operation according to the second embodiment; 
           [0025]      FIG. 14  illustrates a flow of the battery power supply processing operation according to the second embodiment; 
           [0026]      FIG. 15  illustrates a processing operation for preferential battery charge according to the second embodiment; and 
           [0027]      FIG. 16  illustrates a flow of the processing operation for preferential battery charge according to the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0028]    Regarding the above-mentioned electronic devices that can be separated and used, a user can individually use the devices in the mechanically separated state. Therefore, there is a probability that an imbalance between the devices occurs with respect to electric power consumption. 
         [0029]    However, in a technique of related art, electric power transferred between batteries is transferred only in one direction. Therefore, for example, when the user mainly uses a device on a side that can supply electrically charging power using battery power, or the like, there occurs a case in which a battery that can supply electrically charging power has been drained first or prematurely. In such a case, although a battery on a side that can receive a supply of charging power has some energy left, the use of the side that can supply electrically charging power is disturbed. 
         [0030]    A device disclosed hereinafter is capable of adjusting individual remaining battery levels of separable electronic devices between both devices. 
         [0031]    For example, there is provided an electronic device that includes a first chassis capable of receiving electric power supplied from a second chassis. The first chassis includes a first contact section, a first switch, and a first switch control section used for controlling the first switch. The second chassis includes a second contact section configured to be electrically connected to the first contact section, a second battery section including a secondary battery configured to be electrically connected to the second contact section, and a second power source control section used for controlling battery charging for the second battery section. In addition, the second chassis is configured to take modified forms that include a first form, in which the second chassis is electrically connected to the first chassis with respect to a relationship between the first contact section and the second contact section, and a second form in which the second chassis is separated from the first chassis. The first switch is configured to set, in a switching manner, whether or not a first power source capable of supplying electric power for battery charging is electrically connected to the first contact section. When, using the first power source, the second power source control section charges the second battery section, the first switch control section causes the first switch to switch to a state in which the first contact section is electrically connected to the first power source. 
         [0032]    In addition, for example, there is provided an electronic device configured to be connected to another electronic device and to receive electric power supplied from the other electronic device. The electronic device includes a contact section configured to be electrically connected to a contact section in the other electronic device, a switch, and a switch control section used for controlling the switch. In addition, the electronic device is configured to take modified forms that include a first form, in which the electronic device is electrically connected to the other electronic device with respect to a relationship between the contact section and the contact section in the other electronic device, and a second form in which the electronic device is separated from the other electronic device. The switch is configured to set, in a switching manner, whether or not a power source for supplying electric power for battery charging is electrically connected to the contact section. When the other electronic device is charged using the power source, the switch control section causes the switch to switch to a state in which the contact section is electrically connected to the power source. 
         [0033]    In addition, for example, there is provided a power source control device that controls a power source in an electronic device configured to be connected to another electronic device and to receive electric power supplied from the other electronic device. The power source control device controls a switch configured to set, in a switching manner, whether or not a power source, which is capable of supplying electric power for battery charging, is electrically connected to a contact section, which is capable of being electrically connected to a contact section in the other electronic device, and causes the switch to switch to a state, in which the contact section is electrically connected to the power source, when the other electronic device is charged using the power source. According to the electronic device and the power source control device noted above, remaining battery levels of the separable electronic devices may be individually adjusted. 
       First Embodiment 
       [0034]      FIG. 1  illustrates an electronic device according to a first embodiment. Examples of an electronic device  1  according to a first embodiment includes a mobile terminal device, a mobile phone, a portable TV terminal, a portable video game player, and an electronic dictionary device, information processing devices such as e.g., a notebook computer and a personal digital assistant (PDA) or the like. 
         [0035]    The electronic device  1  includes a chassis  1   a  (first chassis) and a chassis  1   b  (second chassis). The chassis  1   b  is separable from the chassis  1   a . The electronic device  1  can be used in any one of a first state in which the chassis  1   a  is integrated with the chassis  1   b  and a second state in which the chassis  1   a  is separated from the chassis  1   b . In addition, the chassis  1   a  and  1   b  can use power sources such as battery sections  1   a   3  and  1   b   3  and power sources  1   a   6  and  1   b   6  or the like, respectively, so the chassis  1   a  and  1   b  are operable independent from each other in a mechanically separated state (second state). In addition, a heavy line illustrated in  FIG. 1  indicates a path through which electric power used for charging the battery section  1   b   3  is supplied from the power source  1   a   6 . 
         [0036]    The chassis  1   a  includes a switch control section  1   a   1  (first switch control section), a switch  1   a   2  (first switch), a battery section  1   a   3  (first battery section), a power source control section  1   a   4  (first power source control section), and a contact section  1   a   5  (first contact section). The chassis  1   a  may be configured to use the power source  1   a   6  (first power source). In addition, the chassis  1   a  may be configured to receive and use electric power supplied from the chassis  1   b.    
         [0037]    When a power source control section  1   b   4  charges the battery section  1   b   3  using the power source  1   a   6 , the switch control section  1   a   1  causes the switch  1   a   2  to switch to a state in which the contact section  1   a   5  is electrically connected to the power source  1   a   6 . 
         [0038]    The switch  1   a   2  is configured to set, in a switching manner, whether or not the power source  1   a   6  that can supply electric power for battery charging is electrically connected to the contact section  1   a   5 . When the switch  1   a   2  connects the power source  1   a   6  to the contact section  1   a   5 , the electric power of the power source  1   a   6  is supplied to the chassis  1   b . In addition, when the electric power of the power source  1   a   6  is not supplied to the chassis  1   b , the switch  1   a   2  does not connect the power source  1   a   6  to the contact section  1   a   5 . 
         [0039]    The battery section  1   a   3  may include a secondary battery that can be electrically connected to the contact section  1   a   5 . When there is no external power source, the chassis  1   a  may be configured to operate independently using electric power stored in the battery section  1   a   3 . 
         [0040]    The power source control section  1   a   4  controls a battery charging operation for the battery section  1   a   3 , which uses electric power supplied from the chassis  1   b  or the like. The contact section  1   a   5  is configured to be electrically connected to the contact section  1   b   5 . The contact sections  1   a   5  and  1   b   5  may include individual contact terminals, for example. In this case, the contact sections  1   a   5  and  1   b   5  are arranged so that contact terminals on the chassis  1   a  and  1   b  have contact with each other when the chassis  1   a  and  1   b  are in an integrated state. Accordingly, electric power may be transferred bidirectionally between the chassis  1   a  and  1   b.    
         [0041]    The power source  1   a   6  is used for operating the chassis  1   a  and charging the battery section  1   b   3 . The power source  1   a   6  may be included in the chassis  1   a  or be an external power source, such as a power source adapter or the like, connected to the chassis  1   a . In addition, the power source  1   a   6  may be the battery section  1   a   3 . In addition, the power source  1   a   6  may be available for charging the battery section  1   a   3 . 
         [0042]    The chassis  1   b  includes a switch control section  1   b   1  (second switch control section), a switch  1   b   2  (second switch), a battery section  1   b   3  (second battery section), a power source control section  1   b   4  (second power source control section), and a contact section  1   b   5  (second contact section). The chassis  1   b  may be configured to use the power source  1   b   6  (second power source). In addition, the chassis  1   b  may take modified forms that include a first form, in which the chassis  1   b  is electrically connected to the chassis  1   a  with respect to a relationship between the contact section  1   a   5  and the contact section  1   b   5 , and a second form in which the chassis  1   b  is separated from the chassis  1   a . In addition, the chassis  1   b  may receive electric power supplied from the chassis  1   a.    
         [0043]    When the power source control section  1   a   4  charges the battery section  1   a   3  using the power source  1   b   6 , the switch control section lbl causes the switch  1   b   2  to switch to a state in which the contact section  1   a   5  is electrically connected to the power source  1   b   6 . 
         [0044]    The switch  1   b   2  is configured to set, in a switching manner, whether or not the power source  1   b   6  that can supply electric power for battery charging is electrically connected to the contact section  1   b   5 . When the switch  1   b   2  connects the power source  1   b   6  to the contact section  1   b   5 , the electric power of the power source  1   b   6  may be supplied to the chassis  1   a . In addition, when the electric power of the power source  1   b   6  is not supplied to the chassis  1   a , the switch  1   b   2  does not connect the power source  1   b   6  to the contact section  1   b   5 . 
         [0045]    The battery section  1   b   3  includes a secondary battery configured to be electrically connected to the contact section  1   b   5 . When there is no external power source, the chassis  1   b  may operate independently using electric power stored in the battery section  1   b   3 . 
         [0046]    The power source control section  1   b   4  controls a battery charging operation for the battery section  1   b   3 , which uses electric power supplied from the chassis  1   a  or the like. The contact section  1   b   5  may be electrically connected to the contact section  1   a   5 . The contact section  1   b   5  may include a contact terminal, as mentioned above. 
         [0047]    The power source  1   b   6  is used for operating the chassis  1   b  and charging the battery section  1   a   3 . The power source  1   b   6  may be included in the chassis  1   b  or be an external power source, such as a power source adapter or the like, connected to the chassis  1   b . In addition, the power source  1   b   6  may be the battery section  1   b   3 . In addition, the power source  1   b   6  may be available for charging the battery section  1   b   3 . 
         [0048]    For example, in the electronic device  1 , when the battery section  1   b   3  is charged using electric power supplied from the power source  1   a   6 , the supplied electric power is transferred to the battery section  1   b   3  through the switch  1   a   2 , the contact sections  1   a   5  and  1   b   5 , the switch  1   b   2 , and the power source control section  1   b   4 . 
         [0049]    According to the electronic device  1 , when there is an imbalance between individual remaining battery levels of separable electronic devices, both remaining battery levels may be adjusted. In addition, since a connection line is shared through which the devices supply electric power to each other, contacts and connection lines arranged between the chassis  1   a  and  1   b  in the electronic device  1  may be simplified. 
         [0050]    In a second embodiment described hereinafter, as an application example of the electronic device  1  according to the first embodiment, a mobile terminal device will be cited. In this regard, however, as mentioned above, the electronic device  1  is applicable to various kinds of electronic devices other than the mobile terminal device. 
       Second Embodiment 
       [0051]      FIGS. 2A to 2F  illustrate the external appearance of a mobile terminal device according to the second embodiment.  FIG. 2A  illustrates the top surface of the mobile terminal device according to the second embodiment.  FIG. 2B  illustrates the left side surface of the mobile terminal device according to the second embodiment.  FIG. 2C  illustrates the front surface of the mobile terminal device according to the second embodiment.  FIG. 2D  illustrates the right side surface of the mobile terminal device according to the second embodiment.  FIG. 2E  illustrates the bottom surface of the mobile terminal device according to the second embodiment.  FIG. 2F  illustrates the back surface of the mobile terminal device according to the second embodiment. 
         [0052]    A mobile terminal device  100  according to the second embodiment is a mobile terminal device that includes a wireless verbal communication function. The mobile terminal device  100  includes an input operation section  110  and an information display section  130 . The input operation section  110  is an example of the chassis  1   a  described above in the first embodiment, and the information display section  130  is an example of the chassis  1   b  in the first embodiment. 
         [0053]    The mobile terminal device  100  illustrated in  FIGS. 2A to 2F  is integrated in a state in which the input operation section  110  overlaps with the information display section  130 . In  FIG. 2 , the input operation section  110  is not extended as described later, but is in a housed state in which the input operation section  110  is retracted. The length along a longitudinal direction (height) and the length along a lateral direction (width) of the input operation section  110  are almost the same as the height and the width of the information display section  130 , respectively. In the housed state, the side surface of the input operation section  110  nearly matches the side surface of the information display section  130 . As illustrated in  FIG. 2C , the information display section  130  includes a display  131   a  on the front thereof. 
         [0054]      FIGS. 3A to 3B  illustrate the external appearance of the mobile terminal device, which is in a mechanically separated state, according to the second embodiment.  FIG. 3A  illustrates the external appearance of an input operation section according to the second embodiment.  FIG. 3B  illustrates the external appearance of an information display section according to the second embodiment. 
         [0055]    In the mobile terminal device  100  according to the embodiment, the input operation section  110  and the information display section  130  may also be used in a state in which the input operation section  110  is separated from the information display section  130 .  FIGS. 3A and 3B  illustrate the input operation section  110  and the information display section  130  that are in a mechanically separated state. 
         [0056]    As illustrated in  FIG. 3A , the input operation section  110  includes a full keyboard section  110   a  and a numerical keypad section  110   b . By sliding the full keyboard section  110  and the numerical keypad section  110   b , the input operation section  110  can be alternately transformed into a housed state in which the numerical keypad section  110   b  is housed and a stretched state in which the numerical keypad section  110   b  is accessible. 
         [0057]    The full keyboard section  110   a  includes a mating hole section  110   a   1  that mates to a camera section  141   a  in the information display section  130 , a full keyboard  111   a  that receives the input of character information, and contact terminals  116   a  and  116   b  that may contact with and be electrically connected to contact terminals  136   a  and  136   b  included in the information display section  130 , respectively. The numerical keypad section  110   b  includes a numerical keypad  111   b  that receives the input of numeric information may be used in connection with a telephone function operation, for example. 
         [0058]    In the embodiment, in a first state in which the input operation section  110  and the information display section  130  in the mobile terminal device  100  are integrated with each other, the full keyboard  111   a  is housed in the mobile terminal device  100 . In addition, when the mobile terminal device  100  is mechanically separated into the input operation section  110  and the information display section  130 , the full keyboard  111   a  is exposed and may be used. In addition, when the mobile terminal device  100  is mechanically separated into the input operation section  110  and the information display section  130 , and, furthermore, the input operation section  110  is put into the stretched state by sliding the input operation section  110 , the numerical keypad  111   b  is exposed and may be used. 
         [0059]    As illustrated in  FIG. 3B , the information display section  130  includes the camera section  141   a  that captures a still image or a moving image, as well as the contact terminals  136   a  and  136   b  that may contact with and be electrically connected to the contact terminals  116   a  and  116   b  included in the input operation section  110 , respectively. When, as described later, the input operation section  110  is integrated with the information display section  130 , the camera section  141   a  mates to the mating hole section  110   a   1  included in the input operation section  110 . 
         [0060]      FIGS. 4A and 4F  illustrate the external appearance of the input operation section according to the second embodiment.  FIG. 4A  illustrates the top surface of the input operation section according to the second embodiment.  FIG. 4B  illustrates the left side surface of the input operation section according to the second embodiment.  FIG. 4C  illustrates the front surface of the input operation section according to the second embodiment.  FIG. 4D  illustrates the right side surface of the input operation section according to the second embodiment.  FIG. 4E  illustrates the bottom surface of the input operation section according to the second embodiment.  FIG. 4F  illustrates the back surface of the input operation section according to the second embodiment. 
         [0061]    The input operation section  110  illustrated in  FIGS. 4A to 4F  is separated from the information display section  130 , and the full keyboard  111   a  in the full keyboard section  110   a  is exposed. In addition, the input operation section  110  is in a housed state in which the numerical keypad  111   b  in the numerical keypad section  110   b  is housed. 
         [0062]    As illustrated in  FIG. 4C , when the input operation section  110  is separated from the information display section  130  and is in the housed state, a user of the mobile terminal device  100  can input character information or the like using the full keyboard  111   a . In addition, the input information may be transmitted to the information display section  130  using a wireless communication function described later. 
         [0063]      FIGS. 5A to 5F  illustrate the external appearance of the information display section according to the second embodiment.  FIG. 5A  illustrates the top surface of the information display section according to the second embodiment.  FIG. 5B  illustrates the left side surface of the information display section according to the second embodiment.  FIG. 5C  illustrates the front surface of the information display section according to the second embodiment.  FIG. 5D  illustrates the right side surface of the information display section according to the second embodiment.  FIG. 5E  illustrates the bottom surface of the information display section according to the second embodiment.  FIG. 5F  illustrates the back surface of the information display section according to the second embodiment. 
         [0064]    The information display section  130  illustrated in  FIGS. 5A to 5F  is in a state in which the information display section  130  is separated from the input operation section  110 , the display  131   a  is arranged on the front face of the information display section  130 , and the camera section  141   a  is arranged on the rear face of the information display section  130 . When, as illustrated in  FIG. 5C , the information display section  130  is separated from the input operation section  110 , the user of the mobile terminal device  100  can cause the display  131   a  to display information that the mobile terminal device  100  obtains using the wireless communication function, information or the like that the input operation section  110  inputs, and information that the mobile terminal device  10  stores, for example. In addition, the user may capture a still image or a moving image using the camera section  141   a.    
         [0065]      FIGS. 6A and 6F  illustrate the external appearance of the input operation section, which is in a stretched state, according to the second embodiment.  FIG. 6A  illustrates the top surface of the input operation section, which is in the stretched state, according to the second embodiment.  FIG. 6B  illustrates the left side surface of the input operation section, which is in the stretched state, according to the second embodiment.  FIG. 6C  illustrates the front surface of the input operation section, which is in the stretched state, according to the second embodiment.  FIG. 6D  illustrates the right side surface of the input operation section, which is in the stretched state, according to the second embodiment.  FIG. 6E  illustrates the bottom surface of the input operation section, which is in the stretched state, according to the second embodiment.  FIG. 6F  illustrates the back surface of the input operation section, which is in the stretched state, according to the second embodiment. 
         [0066]    The input operation section  110  illustrated in  FIGS. 6A to 6F  is separated from the information display section  130 , and the full keyboard  111   a  in the full keyboard section  110   a  is exposed. In addition, the input operation section  110  is in a stretched state, in which the input operation section  110  is stretched by sliding the full keyboard section  110   a  and the numerical keypad section  110   b . In the stretched state, the numerical keypad  111   b  in the numerical keypad section  110   b  is exposed. The input operation section  110  may include a rail section, not illustrated, so that the numerical keypad section  110   b  is slid and hence the input operation section  110  is alternately transformed into the stretched state and the housed state. In addition, the transformation of the state due to the sliding of the numerical keypad section  110   b  is not limited to the example but may be realized using another mechanism. 
         [0067]    As illustrated in  FIG. 6C , when the input operation section  110  is separated from the information display section  130  and is in the stretched state, the user of the mobile terminal device  100  can input character information or the like using the full keyboard  111   a , as well as numeric information by operating the numerical keypad  111   b . In addition, the input information may be transmitted to the information display section  130  using the wireless communication function described later. 
         [0068]      FIGS. 7A to 7F  illustrate the external appearance of a mobile terminal device, which is in a stretched state, according to the second embodiment.  FIG. 7A  illustrates the top surface of the mobile terminal device, which is in the stretched state, according to the second embodiment.  FIG. 7B  illustrates the left side surface of the mobile terminal device, which is in the stretched state, according to the second embodiment.  FIG. 7C  illustrates the front surface of the mobile terminal device, which is in the stretched state, according to the second embodiment.  FIG. 7D  illustrates the right side surface of the mobile terminal device, which is in the stretched state, according to the second embodiment.  FIG. 7E  illustrates the bottom surface of the mobile terminal device, which is in the stretched state, according to the second embodiment.  FIG. 7F  illustrates the back surface of the mobile terminal device, which is in the stretched state, according to the second embodiment. 
         [0069]    The mobile terminal device  100  illustrated in  FIGS. 7A to 7F  is in a stretched state, in which the input operation section  110  and the information display section  130  are integrated with each other, and the full keyboard section  110   a  and the numerical keypad section  110   b  in the input operation section  110  are slid and hence the numerical keypad  111   b  is exposed. 
         [0070]    As illustrated in  FIG. 7F , in the case in which the mobile terminal device  100  is in the stretched state, although the input operation section  110  and the information display section  130  are integrated with each other, the camera section  141   a  is exposed through the mating hole section  110   a   1  because the camera section  141   a  mates to the mating hole section  110   a   1  in the input operation section  110 . 
         [0071]    When, as illustrated in  FIG. 7C , the mobile terminal device  100  is integrated and is in the stretched state, the user of the mobile terminal device  100  can input numeric information by operating the numerical keypad  111   b  and capture a still image or a moving image using the camera section  141   a . The numeric information may be entered in connection with a telephone function operation, for example. In addition, the information input using the input operation section  110  is transmitted to the information display section  130  through the contact terminals  116   a ,  116   b ,  136   a , and  136   b.    
         [0072]      FIG. 8  illustrates the hardware configuration of the mobile terminal device according to the second embodiment. As described above, the mobile terminal device  100  according to the second embodiment includes the input operation section  110  and the information display section  130 . The input operation section  110  and the information display section  130  may perform contact communication and wireless communication in order to perform various kinds of controls including controls for power sources included in individual devices. In addition, the input operation section  110  and the information display section  130  may be used independently from each other. 
         [0073]    The input operation section  110  includes a keyboard section  111 , a microphone  112 , an operation section  113 , a control section  114 , a switching control section  115 , a contact section  116 , a detection section  117 , a power source control section  118 , a battery section  119 , and a wireless communication section  120 . 
         [0074]    The keyboard section  111  includes the full keyboard  111   a  and the numerical keypad  111   b , described above, and, by detecting a key operation thereof, receives the input of numeric information, character information, and other input information. When the keyboard section  111  detects the key operation, the keyboard section  111  outputs an input signal indicating an operated key to the control section  134  of the display section through the control section  114  of the input operation section. 
         [0075]    The microphone  112  receives an audio input signal by converting a sonic physical oscillation into an electrical signal, and outputs the received audio input signal to the control section  134  of the display section through the control section  114  of the input operation section. For example, during the user&#39;s phone call, the user&#39;s voice and a background noise on the user&#39;s side are input to the microphone  112 . 
         [0076]    The operation section  113  includes an input device such as an operation key, an operation button, a touch panel, or the like, and receives operations such as a power on/off operation and switching between various kinds of modes or the like. The control section  114  controls the entire mobile terminal device  100 . The control section  114  may be realized using, for example, a central processing unit (CPU), a random access memory (RAM), and a read only memory (ROM). In addition, for example, the control section  114  includes an interface such as an inter-integrated circuit (I2C), a serial peripheral interface (SPI), a universal asynchronous receiver transmitter (UART), a universal serial bus (USB), or the like, which can be connected to a peripheral device. The CPU reads out and deploys a program and data from the ROM and in the RAM, and executes the program. The RAM is a volatile memory used for temporarily storing a portion of the program or the data. In addition, in place of the RAM, other kinds of memories may be used. The ROM is a nonvolatile memory used for storing the program and the data that the control section  114  is to use. In addition, in place of the ROM, for example, a flash memory may be used. Control operations performed in the control section  114  include a communication control operation, an audio input/output control operation, and a key operation control operation or the like. In addition, the control section  114  controls, in a switching manner, a switch used to set whether or not individual sections in the input operation section  110 , such as the contact section  116  and the battery section  119  or the like, are connected to the external power source or the like, such as the adapter or the like. Accordingly, when the battery section  119  is charged or supplies charging power, or the like, the connection state may be switched. 
         [0077]    The switching control section  115  performs a switching control for a switch used to set whether or not individual sections in the input operation section  110  are connected to the external power source or the like, such as the adapter or the like. Accordingly, when the battery section  119  is charged or supplies charging power, or the like, the connection state may be switched. 
         [0078]    The contact section  116  is electrically connected to the contact section  136  included in the information display section  130 . In the input operation section  110 , data communicated between the input operation section  110  and the information display section  130  and electric power that the input operation section  110  and the information display section  130  supply to each other are transmitted though the contact section  116 . For example, the contact section  116  includes contact terminals such as the contact terminal  116   a  through which the input operation section  110  and the information display section  130  supply electric power to each other and the contact terminal  116   b  that performs an integration detection operation in which it is determined whether the input operation section  110  and the information display section  130  are in the integrated state or in the mechanically separated state. 
         [0079]    The detection section  117  detects voltages of individual sections in the input operation section  110 . Accordingly, it is detected whether or not the information display section  130  or the external power source supplies electric power to the input operation section  110 , or the like. The power source control section  118  controls the supply of power to individual sections in the input operation section  110  from the battery section  119  or the external power source. In addition, the power source control section  118  detects the remaining battery level of the battery section  119 . In addition, the power source control section  118  controls battery charging for the battery section  119 . In addition, the power source control section  118  detects and gives notice of the charging status of the battery section  119 . 
         [0080]    The power source control section  118  has information (for example, graph, table, function, or the like) indicating a correspondence relationship between the remaining battery level of the battery section  119  and the interelectrode voltage of the battery section  119 . The power source control section  118  detects the interelectrode voltage of the battery section  119 , and detects the remaining battery level of the battery section  119  on the basis of the information indicating the correspondence relationship and the interelectrode voltage of the battery section  119 . 
         [0081]    The battery section  119  includes a secondary battery (storage battery) that stores electric charge. The battery section  119  may be charged by receiving electric power supplied from the external power source connected to the input operation section  110  or the information display section  130 . The battery section  119  may be charged, repeatedly used as a battery, and supply electric power to the input operation section  110  using the secondary battery. While, as the battery, a lithium-ion battery is used in the embodiment, the embodiment is not limited to only the lithium-ion battery. Instead, all kinds of secondary batteries may be used as the battery according to example embodiments described herein. 
         [0082]    The wireless communication section  120  performs wireless communication with the information display section  130  in accordance with the control of the control section  114 . For example, the communications may be carried using communication methods such as e.g., Bluetooth (registered trademark), Zigbee, a wireless USB, and a wireless local area network (LAN) or the like. 
         [0083]    The information display section  130  includes a display section  131 , a speaker  132 , an operation section  133 , a control section  134 , a switching control section  135 , a contact section  136 , a detection section  137 , a power source control section  138 , a battery section  139 , a wireless communication section  140 , and an imaging section  141 . 
         [0084]    The display section  131  performs various notification operations for the user by lighting various lamps or displaying various images on the display  131   a  in accordance with the control of the control section  134 . In the display section  131 , for example, light emitting diodes (LEDs) may be used as lamps. In addition, in the display section  131 , a liquid crystal display (LCD) or an organic electro luminescence (EL) display may be used as the display  131   a . Examples of images displayed on the display  131   a  include a standby screen, an operation screen, text, and a content picture or the like. 
         [0085]    In accordance with the control of the control section  134 , the speaker  132  converts an electrical signal into a physical oscillation and reproduces sound. For example, during the user&#39;s phone call, an intended party&#39;s voice and background noise on the intended party&#39;s side may be output from the speaker  132 . 
         [0086]    The operation section  133  includes an input device such as an operation key, an operation button, a touch panel, or the like, and receives operations such as a power on/off operation and a switching between modes operation, for example. The control section  134  controls the entire mobile terminal device  100 . The control section  134  can be realized using, for example, a CPU, a RAM, and a ROM, in the same way as the control section  114 . In addition, for example, the control section  134  includes an interface such as an I2C, a SPI, a UART, a USB, or the like, which can be connected to a peripheral device. The CPU reads out and deploys a program and data from the ROM and in the RAM, and executes the program. The RAM is a volatile memory used for temporarily storing a portion of the program or the data. In addition, in place of the RAM, other kinds of memories may be used. The ROM is a nonvolatile memory used for storing the program and the data that the control section  134  is to use. In addition, in place of the ROM, for example, a flash memory may be used. Control operations performed in the control section  134  include a communication control operation, an audio input/output control operation, and a key operation control operation or the like. In addition, the control section  134  controls, in a switching manner, a switch used to set whether or not individual sections in the information display section  130 , such as the contact section  136  and the battery section  139  or the like, are connected to the external power source or the like, such as the adapter or the like. Accordingly, when the battery section  139  is charged or supplies charging power, or the like, the connection state may be switched. 
         [0087]    The switching control section  135  performs a switching control for a switch used to set whether or not individual sections in the input operation section  130  are connected to the external power source or the like, such as the adapter or the like. Accordingly, when the battery section  139  is charged or supplies charging power, or the like, the connection state may be switched. 
         [0088]    The contact section  136  is electrically connected to the contact section  116  included in the input operation section  110 . In the information display section  130 , data communicated between the input operation section  110  and the information display section  130  and electric power that the input operation section  110  and the information display section  130  supply to each other are transmitted through the contact section  136 . For example, the contact section  136  includes contact terminals such as the contact terminal  136   a  through which the input operation section  110  and the information display section  130  supply electric power to each other and the contact terminal  136   b  that performs an integration detection operation in which it is determined whether the input operation section  110  and the information display section  130  are in the integrated state or in the mechanically separated state. 
         [0089]    The detection section  137  detects voltages of individual sections in the information display section  130 . Accordingly, it is detected whether or not the information display section  130  or the external power source supplies electric power to the information display section  130 , or the like. The power source control section  138  controls the supply of power to individual sections in the information display section  130  from the battery section  139  or the external power source. In addition, the power source control section  138  detects the remaining battery level of the battery section  139 . In addition, the power source control section  138  controls battery charging for the battery section  139 . In addition, the power source control section  138  detects and gives notice of the charging status of the battery section  139 . 
         [0090]    The power source control section  138  has information indicating a correspondence relationship between the remaining battery level of the battery section  139  and the interelectrode voltage of the battery section  139 . The power source control section  138  detects the interelectrode voltage of the battery section  139 , and detects the remaining battery level of the battery section  139  on the basis of the information indicating the correspondence relationship and the interelectrode voltage of the battery section  139 . 
         [0091]    The battery section  139  includes a secondary battery (storage battery) that stores electric charge. The battery section  139  may be charged by receiving electric power supplied from the external power source connected to the information display section  130  or the input operation section  110 . The battery section  139  may be charged, repeatedly used as a battery, and supply electric power to the information display section  130  using the secondary battery. While, as the battery, a lithium-ion battery is used in the embodiment, the embodiment is not limited to only the lithium-ion battery. Instead, all kinds of secondary batteries may be used as the battery according to an example embodiment. 
         [0092]    The wireless communication section  140  performs wireless communication with the input operation section  110  in accordance with the control of the control section  134 . In addition, the wireless communication section  140  performs wireless communication with a public line in accordance with the control of the control section  134 . The wireless communication section  140  uses, for example, one of communication methods such as e.g., Bluetooth, Zigbee, a wireless USB, and a wireless LAN or the like. In addition, the wireless communication section  140  may directly wireless-communicate with the public line, using, for example, a mobile communication such as a wideband code division multiple access (W-CDMA) communication or the like, or communicate with the public line through a wireless LAN such as IEEE802.11a/b/g/n or the like. 
         [0093]    The imaging section  141  includes a camera section  141   a , and converts a still image or a moving image, captured by the camera section  141   a , into image data. In addition, the input operation section  110  and the information display section  130  include the power source control sections  118  and  138  and the battery sections  119  and  139 , respectively, so that the input operation section  110  and the information display section  130  may operate independently in the mechanically separated state. 
         [0094]    A power-off state includes a standby state in which functions other than both a power source operation for one device and a function used for monitoring the power source of the other device are restricted, and hence power consumption is reduced. For example, the power-off state includes a state in which power is not supplied to individual sections other than power source control sections (for example, the power source control section  118  in the case of the input operation section  110 ) in individual devices. 
         [0095]      FIG. 9  illustrates the function of the mobile terminal device according to the second embodiment. Descriptions relating to functions other than a battery charge control function are omitted for the sake of brevity. The mobile terminal device  100  includes the input operation section  110  (first chassis) and the information display section  130  (second chassis). The information display section  130  may be separated from the input operation section  110 . The mobile terminal device  100  may be used in a first state in which the input operation section  110  is integrated with the information display section  130  and a second state in which the input operation section  110  is separated from the information display section  130 . In addition, the input operation section  110  may receive electric power supplied from the information display section  130 . Further, the information display section  130  may receive electric power supplied from the input operation section  110 . In addition, the input operation section  110  and the information display section  130  are configured to take modified forms that include a first form (integrated state), in which the input operation section  110  is mechanically and electrically connected to the information display section  130  with respect to a relationship between the contact section  116  and the contact section  136 , and a second form (mechanically separated state) in which the input operation section  110  is separated from the information display section  130 . 
         [0096]    The control section  114  obtains signals transmitted from a detection section  117   a , the power source control section  118 , and the control section  134 . In addition, by transmitting a control signal to the switching control section  115  on the basis of the obtained signals, the control section  114  causes the switching control section  115  to control switches  122   a  and  122   b . In addition, the control section  114  controls a switch  122   c  on the basis of the obtained signals. The switching control section  115  controls the switches  122   a  and  122   b  on the basis of the control signal transmitted from the control section  114  and signals obtained from the detection section  117   a , a detection section  117   b , the power source control section  118 , and the contact terminal  116   b . The control section  114  and the switching control section  115  function as a switch control section. 
         [0097]    When a battery charging operation, described later with reference to  FIGS. 15 and 16 , is performed, the control section  114  may determine the completion of the battery charging operation by comparing the remaining battery level of the battery section  119  with a specified voltage, which is lower than a remaining battery level at the time of full charge, on the basis of the detection of the remaining battery level of the battery section  119 , performed by the power source control section  118 . Accordingly, when the battery charging operation is performed, the battery section  119  and the battery section  139  are charged effectively. 
         [0098]    When the power source control section  138  charges the battery section  139  using the adapter connected to the adapter terminal  123 , the switching control section  115  causes the switch  122   a  to switch to a state in which the contact terminal  116   a  is electrically connected to the adapter connected to the adapter terminal  123 . 
         [0099]    When the power source control section  138  charges the battery section  139  using the battery section  119 , the switching control section  115  causes the switch  122   b  to switch to a state in which the contact terminal  116   a  is electrically connected to the battery section  119 . 
         [0100]    In addition, when the remaining battery level of the battery section  119  is compared with the remaining battery level of the battery section  139 , the remaining battery level of the battery section  139  is lower than that of the battery section  119 , and a battery charging operation is performed using the adapter connected to the adapter terminal  123 , the control section  114  and the switching control section  115  can cause the switch  122   c  to switch to a state in which the battery section  119  is not electrically connected to the adapter terminal  123 , and cause the switch  122   a  to switch to a state in which the contact terminal  116   a  is electrically connected to the adapter terminal  123 . In this case, after the battery charging operation for the battery section  139  is completed, the control section  114  and the switching control section  115  cause the switch  122   c  to switch to a state in which the battery section  119  is electrically connected to the adapter terminal  123 , and cause the switch  122   a  to switch to a state in which the contact terminal  116   a  is not electrically connected to the adapter terminal  123 . Accordingly, when the remaining battery level of the battery section  119  is low, the battery charging operation in which the battery section  119  is charged is performed. 
         [0101]    In addition, when the detection section  117   b  detects a voltage supplied from the contact terminal  116   a , the switching control section  115  causes the switch  122   b  to switch to a state in which the battery section  119  is not electrically connected to the contact terminal  116   a.    
         [0102]    In addition, using the contact terminals  116   b  and  136   b , the switching control section  115  detects whether the input operation section  110  and the information display section  130  are in the integrated state or in the mechanically separated state. When, on the basis of the contact terminals  116   b  and  136   b , it is detected that the input operation section  110  and the information display section  130  are in the mechanically separated state, the switching control section  115  causes the switches  122   a  and  122   b  to switch to a state in which the adapter terminal  123  is not electrically connected to the contact terminal  116   a  and a state in which the battery section  119  is not electrically connected to the contact terminal  116   a , respectively. 
         [0103]    When the power source control section  118  charges the battery section  119  using the adapter connected to the adapter terminal  123 , the switching control section  115  causes the switch  122   a  to switch to a state in which the contact terminal  116   a  is not electrically connected to the adapter connected to the adapter terminal  123 . 
         [0104]    The contact section  116  can be electrically connected to the contact section  136 . The contact section  116  includes the contact terminals  116   a ,  116   b , and  116   c . In the contact section  116 , the contact terminals  116   a ,  116   b , and  116   c  are arranged so as to have contact with corresponding contact terminals in the contact section  136  when the input operation section  110  and the information display section  130  are in the integrated state. Accordingly, communication and power transfer may be performed between the input operation section  110  and the information display section  130 . 
         [0105]    The contact terminals  116   a ,  116   b , and  116   c  are projected a little from the surface of the input operation section  110  so as to easily have contact with the contact terminals  136   a  and  136   b  and a contact terminal  136   c  in the contact section  136  included in the information display section  130 , respectively. In addition, the peripheries of the contact terminals  116   a ,  116   b , and  116   c  may be dented and the contact section  136  may be projected so that the contact section  116  mates with the contact section  136  and the contact terminals  116   a ,  116   b , and  116   c  have contact with the contact terminals  136   a ,  136   b , and  136   c , respectively. 
         [0106]    The contact terminal  116   a  is a contact terminal that can be connected to the contact terminal  136   a  and is used for supplying electric power by having contact with the information display section  130 . The input operation section  110  supplies and receives charging power to and from the information display section  130  through the contact terminal  116   a.    
         [0107]    The contact terminal  116   b  is a contact terminal that can be connected to the contact terminal  136   b  and is used for detecting, by having contact with the information display section  130 , whether the input operation section  110  and the information display section  130  are in the integrated state or in the mechanically separated state. 
         [0108]    The contact terminal  116   c  is a contact terminal that can be connected to the contact terminal  136   c  and is used for performing contact communication with the information display section  130 . The control section  114  transmits and receives communication data and a control signal to and from the control section  134  through the contact terminal  116   c.    
         [0109]    The detection section  117   a  detects a voltage supplied from the adapter connected to the adapter terminal  123 . When the detection section  117   a  detects the voltage supplied from the adapter, the detection section  117   a  outputs the adapter voltage detection result to the control section  114  and the switching control section  115 . 
         [0110]    The detection section  117   b  detects a voltage supplied from the information display section  130  through the contact terminal  116   a . When the detection section  117   b  detects the voltage supplied from the information display section  130  through the contact terminal  116   a , the detection section  117   b  outputs the facing device voltage detection result to the switching control section  115 . 
         [0111]    The power source control section  118  controls a battery charging operation for the battery section  119 , which uses electric power supplied from the adapter, connected to the adapter terminal  123 , or the information display section  130 . In addition, the power source control section  118  notifies the control section  114  of a remaining battery level notification that gives notice of the remaining battery level of the battery section  119 . In addition, the power source control section  118  notifies the switching control section  115  of a charging status notification that indicates whether or not the battery section  119  is being charged. 
         [0112]    In the case in which the battery section  119  is being charged, when the remaining battery level of the battery section  119  reaches a full charge level during a full charge operation, the power source control section  118  determines that the battery charging operation is completed. 
         [0113]    In addition, in the case in which the battery section  119  is being charged, when the remaining battery level of the battery section  119  reaches a specified remaining battery level, which is lower than the remaining battery level of the battery section  139  at the time of full charge, the power source control section  118  may determine that the battery charging operation is completed. Accordingly, when the remaining battery level comes close to the full charge level, the control section  114  completes the battery charging operation for the battery section  119 , and the battery section  139  begins charging. Therefore, a high electric charge effect can be obtained or maintained. 
         [0114]    The battery section  119  includes the secondary battery that can be electrically connected to the contact terminal  116   a . When there is no external power source, the input operation section  110  can also operate independently using electric power stored in the battery section  119 . 
         [0115]    The switch  122   a  may be used to set, in a switching manner, whether or not the adapter terminal  123  is electrically connected to the contact terminal  116   a . When the switch  122   a  connects the adapter terminal  123  to the contact terminal  116   a , electric power can be supplied from the adapter connected to the adapter terminal  123  to the information display section  130 . In addition, when electric power is not supplied from the adapter connected to the adapter terminal  123  to the information display section  130 , the switch  122   a  does not connect the adapter terminal  123  to the contact terminal  116   a.    
         [0116]    The switch  122   b  may be used to set, in a switching manner, whether or not the battery section  119  is electrically connected to the contact terminal  116   a . When the switch  122   b  connects the battery section  119  to the contact terminal  116   a , electric power can be supplied from the battery section  119  to the information display section  130 . In addition, when electric power is not supplied from the battery section  119  to the information display section  130 , the switch  122   b  does not connect the battery section  119  to the contact terminal  116   a.    
         [0117]    The switch  122   c  may be used to set, in a switching manner, whether or not the battery section  119  is electrically connected to the adapter terminal  123 . Accordingly, the switch  122   c  can control whether or not the battery section  119  receives electronic power supplied from the adapter connected to the adapter terminal  123 . 
         [0118]    The adapter (for example, an adapter  200  described later with reference to  FIG. 11 ) that is an external power source is configured to be connected to the adapter terminal  123 . The adapter may be an adapter that converts commercial power supply to an electric current that the input operation section  110  can use and supplies the electric current, or may be an adapter that converts other power supply to an electric current that the input operation section  110  can use and supplies the electric current. In addition, the adapter terminal  123  may be able to receive electronic power supplied using a method, such as an external battery or the like, other than the adapter. 
         [0119]    The control section  134  obtains signals transmitted from the control section  114 , a detection section  137   a , and the power source control section  138 . In addition, by transmitting a control signal to the switching control section  135  on the basis of the obtained signals, the control section  134  causes the switching control section  135  to control switches  142   a  and  142   b . In addition, the control section  134  controls a switch  142   c  on the basis of the obtained signals. The switching control section  135  controls the switches  142   a  and  142   b  on the basis of the control signal transmitted from the control section  114  and signals obtained from the detection section  137   a , a detection section  137   b , the power source control section  138 , and the contact terminal  136   b . The control section  134  and the switching control section  135  function as a switch control section. 
         [0120]    When the adapter is connected to the adapter terminal  143  and the power source control section  118  charges the battery section  119  using the adapter, the switching control section  135  causes the switch  142   a  to switch to a state in which the contact terminal  136   a  is electrically connected to the adapter connected to the adapter terminal  143 . 
         [0121]    When the power source control section  118  charges the battery section  119  using the battery section  139 , the switching control section  135  causes the switch  142   b  to switch to a state in which the contact terminal  136   a  is electrically connected to the battery section  139 . 
         [0122]    In addition, when the remaining battery level of the battery section  139  is compared with the remaining battery level of the battery section  119 , the remaining battery level of the battery section  119  is lower than that of the battery section  139 , and a battery charging operation is performed using the adapter connected to the adapter terminal  143 , the control section  134  and the switching control section  135  may cause the switch  142   c  to switch to a state in which the battery section  139  is not electrically connected to the adapter terminal  143 , and cause the switch  142   a  to switch to a state in which the contact terminal  136   a  is electrically connected to the adapter terminal  143 . In this case, after the battery charging operation for the battery section  119  is completed, the control section  134  and the switching control section  135  cause the switch  142   c  to switch to a state in which the battery section  139  is electrically connected to the adapter terminal  143 , and cause the switch  142   a  to switch to a state in which the contact terminal  136   a  is not electrically connected to the adapter terminal  143 . Accordingly, when the remaining battery level of the battery section  139  is low, the battery charging operation in which the battery section  139  is charged may be performed. 
         [0123]    When a battery charging operation, described later with reference to  FIGS. 15 and 16 , is performed, the control section  134  may determine the completion of the battery charging operation by comparing the remaining battery level of the battery section  139  with a specified voltage, which is lower than a remaining battery level at the time of full charge, on the basis of the detection of the remaining battery level of the battery section  139 , performed by the power source control section  138 . Accordingly, when the battery charging operation is performed, the battery section  119  and the battery section  139  may be effectively charged. 
         [0124]    In addition, when the detection section  137   b  detects a voltage supplied from the contact terminal  136   a , the switching control section  135  causes the switch  142   b  to switch to a state in which the battery section  139  is not electrically connected to the contact terminal  136   a.    
         [0125]    In addition, using the contact terminals  116   b  and  136   b , the switching control section  135  detects whether the input operation section  110  and the information display section  130  are in the integrated state or in the mechanically separated state. When it is detected that the input operation section  110  and the information display section  130  are in the mechanically separated state on the basis of the contact terminals  116   b  and  136   b , the switching control section  135  causes the switches  142   a  and  142   b  to switch to a state in which the adapter terminal  143  is not electrically connected to the contact terminal  136   a  and a state in which the battery section  139  is not electrically connected to the contact terminal  136   a , respectively. 
         [0126]    When the power source control section  138  charges the battery section  139  using the adapter connected to the adapter terminal  143 , the switching control section  135  causes the switch  142   a  to switch to a state in which the contact terminal  136   a  is not electrically connected to the adapter connected to the adapter terminal  143 . 
         [0127]    The contact section  136  may be electrically connected to the contact section  116 . The contact section  136  includes the contact terminals  136   a ,  136   b , and  136   c . In the contact section  136 , the contact terminals  136   a ,  136   b , and  136   c  are arranged so as to have contact with corresponding contact terminals in the contact section  116  when the input operation section  110  and the information display section  130  are in the integrated state. Accordingly, communication and power transfer may be performed between the information display section  130  and the input operation section  110 . 
         [0128]    The contact terminals  136   a ,  136   b , and  136   c  are projected a little from the surface of the information display section  130  so as to easily have contact with the contact terminals  116   a ,  116   b  and  116   c  in the contact section  116  included in the input operation section  110 , respectively. In addition, the peripheries of the contact terminals  136   a ,  136   b , and  136   c  may be dented and the contact section  116  may be projected so that the contact section  136  mates with the contact section  116  and the contact terminals  136   a ,  136   b , and  136   c  have contact with the contact terminals  116   a ,  116   b , and  116   c , respectively. 
         [0129]    The contact terminal  136   a  is a contact terminal that may be connected to the contact terminal  116   a  and is used for supplying electric power by having contact with the input operation section  110 . The information display section  130  supplies and receives charging power to and from the input operation section  110  through the contact terminal  136   a.    
         [0130]    The contact terminal  136   b  is a contact terminal that may be connected to the contact terminal  116   b  and is used for detecting, by having contact with the input operation section  110 , whether the information display section  130  and the input operation section  110  are in the integrated state or in the mechanically separated state. 
         [0131]    The contact terminal  136   c  is a contact terminal that may be connected to the contact terminal  116   c  and is used for performing contact communication with the input operation section  110 . The control section  134  transmits and receives communication data and a control signal to and from the control section  114  through the contact terminal  136   c.    
         [0132]    The detection section  137   a  detects a voltage supplied from the adapter connected to the adapter terminal  143 . When the detection section  137   a  detects the voltage supplied from the adapter connected to the adapter terminal  143 , the detection section  137   a  outputs the adapter voltage detection result to the control section  134  and the switching control section  135 . 
         [0133]    The detection section  137   b  detects a voltage supplied from the input operation section  110  through the contact terminal  136   a . When the detection section  137   b  detects the voltage supplied from the input operation section  110  through the contact terminal  136   a , the detection section  137   b  outputs the facing device voltage detection result to the switching control section  135 . 
         [0134]    The power source control section  138  controls a battery charging operation for the battery section  139 , which uses electric power supplied from the adapter, connected to the adapter terminal  143 , or the input operation section  110 . In addition, the power source control section  138  notifies the control section  134  of a remaining battery level notification that gives notice of the remaining battery level of the battery section  139 . In addition, the power source control section  138  notifies the switching control section  135  of a charging status notification that indicates whether or not the battery section  139  is being charged. 
         [0135]    In addition, in the case in which the battery section  139  is being charged, when the remaining battery level of the battery section  139  reaches a full charge level during a full charge operation, the power source control section  138  determines that the battery charging operation is completed. 
         [0136]    In addition, in the case in which the battery section  139  is being charged, when the remaining battery level of the battery section  139  reaches a specified remaining battery level, which is lower than the remaining battery level of the battery section  139  at the time of full charge, the power source control section  138  may determine that the battery charging operation is completed. Accordingly, when the remaining battery level comes close to the full charge level, the control section  134  may complete the battery charging operation for the battery section  139 , in order to instead charge the battery section  119 . Therefore, a high electric charge effect may be obtained and/or maintained. 
         [0137]    The battery section  139  includes the secondary battery that may be electrically connected to the contact terminal  136   a . When there is no external power source, the information display section  130  can also operate independently using electric power stored in the battery section  139 . 
         [0138]    The switch  142   a  may be used to set, in a switching manner, whether or not the adapter terminal  143  is electrically connected to the contact terminal  136   a . When the switch  142   a  connects the adapter terminal  143  to the contact terminal  136   a , electric power may be supplied from the adapter connected to the adapter terminal  143  to the input operation section  110 . In addition, when electric power is not supplied from the adapter connected to the adapter terminal  143  to the input operation section  110 , the switch  142   a  does not connect the adapter terminal  143  to the contact terminal  136   a.    
         [0139]    The switch  142   b  may be used to set, in a switching manner, whether or not the battery section  139  is electrically connected to the contact terminal  136   a . When the switch  142   b  connects the battery section  139  to the contact terminal  136   a , electric power may be supplied from the battery section  139  to the input operation section  110 . In addition, when electric power is not supplied from the battery section  139  to the input operation section  110 , the switch  142   b  does not connect the battery section  139  to the contact terminal  136   a.    
         [0140]    The switch  142   c  may be used to set, in a switching manner, whether or not the battery section  139  is electrically connected to the adapter terminal  143 . Accordingly, the switch  142   c  may control whether or not the battery section  139  receives electronic power supplied from the adapter connected to the adapter terminal  143 . 
         [0141]    The adapter that is an external power source is configured to be connected to the adapter terminal  143 . The adapter may be an adapter that converts commercial power supply to an electric current that the information display section  130  may use and supplies the electric current, or may be an adapter that converts other power supply to an electric current that the information display section  130  may use and supplies the electric current. In addition, the adapter terminal  143  may be able to receive electronic power supplied using a method, such as an external battery or the like, other than the adapter. In addition, the adapter terminal  143  may be able to be connected to an adapter that can be connected to the adapter terminal  123 , and may be used by being connected to a power source different from the adapter. 
         [0142]    In addition, in the embodiment, the input operation section  110  includes the control section  114  and the switching control section  115 , and the information display section  130  includes the control section  134  and the switching control section  135 . However, the configuration is not limited to the example. The input operation section  110  may include a power source control device that includes the functions of the control section  114  and the switching control section  135 , and the information display section  130  may include a power source control device that includes the functions of the control section  134  and the switching control section  135 . In addition, by controlling the power sources in the input operation section  110  and the information display section  130 , the power source control devices may realize the same functions as the control section  114 , the switching control section  135 , the control section  134 , and the switching control section  135 . 
         [0143]      FIG. 10  illustrates a logic circuit for the switching control section according to the second embodiment. The switching control section  115  according to the second embodiment includes a logic circuit, which has positive logic, illustrated in  FIG. 10 . Here, while  FIG. 10  illustrates the switching control section  115 , the switching control section  135  has the same logic circuit. 
         [0144]    The switching control section  115  includes AND circuits  115   a ,  115   b ,  115   c , and  115   d , an OR circuit  115   e , NOT circuits  115   f ,  115   g ,  115   h , and  115   i , and the circuits are arranged as illustrated in  FIG. 10 . In addition, the switching control section  115  and input/output signals thereof are not limited to the logic circuit and signals illustrated in  FIG. 10 . As the switching control section  115  and the input/output signals, different logic circuit and different signals, which have the same functions, may be adopted. 
         [0145]    The switching control section  115  receives, as input signals, a facing device supply voltage detection result from the detection section  117   b , an integration detection result from the contact terminal  116   b , a control signal from the control section  114 , the charging status notification from the power source control section  118 , and an adapter voltage detection result from the detection section  117   a , and controls the switches  122   a  and  122   b  by outputting control signals to the switches  122   a  and  122   b  on the basis of the input signals. 
         [0146]    The facing device supply voltage detection result is a signal transmitted from the detection section  117   b . The facing device supply voltage detection result indicates whether or not a voltage supplied from the information display section  130  is detected. For example, when the voltage is detected, the facing device supply voltage detection result turns into a high-level signal, and when the voltage is not detected, the facing device supply voltage detection result turns into a low-level signal. 
         [0147]    The integration detection result is a signal transmitted from the contact terminal  116   b . The integration detection result indicates whether the input operation section  110  is separated from the information display section  130  or the input operation section  110  is integrated with the information display section  130 . For example, when the input operation section  110  is separated from the information display section  130 , the integration detection result turns into a high-level signal, and when the input operation section  110  is integrated with the information display section  130 , the integration detection result turns into a low-level signal. 
         [0148]    The control signal is a signal transmitted from the control section  114 . The control signal indicates whether or not electric power is to be supplied from the battery section  119  to the information display section  130  through the contact terminal  116   a  in order to charge the battery section  139 . For example, when electric power is to be supplied, the control signal turns into a high-level signal, and when electric power is not to be supplied, the control signal turns into a low-level signal. 
         [0149]    The charging status notification is a signal transmitted from the power source control section  118 . The charging status notification indicates whether or not the battery section  119  is currently charged. For example, when the battery section  119  is currently being charged, the charging status notification turns into a high-level signal, and when the battery section  119  is not currently being charged, the control signal turns into a low-level signal. 
         [0150]    The adapter voltage detection result is a signal transmitted from the detection section  117   a . The adapter voltage detection result indicates whether or not an adapter that externally supplies electric power is connected to the input operation section  110  through the adapter terminal  123 . For example, when the adapter is connected, the adapter voltage detection result turns into a high-level signal, and when the adapter is not connected, the adapter voltage detection result turns into a low-level signal. 
         [0151]    The switch  122   a  is a switch that is used to set, in a switching manner, whether or not the adapter terminal  123  is electrically connected to the contact terminal  116   a . When a signal transmitted from the AND circuit  115   c  is a high-level signal, the switch  122   a  turns into an on-state, and when the signal transmitted from the AND circuit  115   c  is a low-level signal, the switch  122   a  turns into an off-state. 
         [0152]    The switch  122   b  is a switch that is used to set, in a switching manner, whether or not the battery section  119  is electrically connected to the contact terminal  116   a . When a signal transmitted from the AND circuit  115   a  is a high-level signal, the switch  122   b  turns into an on-state, and when the signal transmitted from the AND circuit  115   a  is a low-level signal, the switch  122   b  turns into an off-state. 
         [0153]    In addition, the switching control section  135  controls the switches  122   a  and  122   b  so that the switches  122   a  and  122   b  do not simultaneously turn into the on-states. Accordingly, the adapter and the battery section  119  are inhibited or prevented from supplying electric power to the information display section  130  through the contact terminals  116   a  and  136   a  at the same time. 
         [0154]    In addition, the switching control section  135  controls the switches  122   a  and  122   b  so that both the switches  122   a  and  122   b  turn into the off-states when the input operation section  110  is mechanically separated from the information display section  130 . Accordingly, when the input operation section  110  and the information display section  130  are in the mechanically separated state, voltages supplied from the adapter and the battery section  119  are inhibited or prevented from being applied to the contact terminal  116   a.    
         [0155]    In addition, the switching control section  135  controls the switches  122   a  and  122   b  so that charging power is supplied from the adapter connected to the adapter terminal  123  to one of the input operation section  110  and the information display section  130 . Accordingly, the adapter is inhibited or prevented from becoming overloaded in case of charge, and an excessive electric current is prevented from flowing in the mobile terminal device  100 . 
         [0156]      FIG. 11  illustrates a processing operation performed when the input operation section and the information display section are charged using the adapter connected to the input operation section according to the second embodiment. In the embodiment, when an adapter terminal arranged in one of the input operation section  110  and the information display section  130  included in the mobile terminal device  100 , charging power is supplied. For example, when the adapter terminal  123  is arranged in the input operation section  110 , is connected to the adapter  200  that supplies charging power, the battery sections  119  and  139  can be charged through the input operation section  110 . 
         [0157]    As illustrated in  FIG. 11 , the adapter  200  is connected to the adapter terminal  123  arranged in the input operation section  110 .  FIG. 11  illustrates the mobile terminal device  100  in which the battery section  139  is being charged after a battery charging operation for the battery section  119 , performed by the adapter  200 , has been completed. In addition, an adapter is not connected to the adapter terminal  143  arranged in the information display section  130 . 
         [0158]    The contact terminals  116   a ,  116   b , and  116   c  are connected to the contact terminals  136   a ,  136   b , and  136   c , respectively. Using the connection between the contact terminals  116   a  and  136   a , the input operation section  110  and the information display section  130  can supply charging power to each other. Using the connection between the contact terminals  116   b  and  136   b , the switching control sections  115  and  135  detect the integration of the input operation section  110  and the information display section  130 . Using the connection between the contact terminals  116   c  and  136   c , the control section  114  can transmit and receive control signals to and from the control section  134 . 
         [0159]    The detection section  117   a  detects the voltage of the adapter  200  connected to the adapter terminal  123 , and outputs the adapter voltage detection result to the control section  114  and the switching control section  115  (e.g., a high-level signal may be output to the control section  114  and the switching control section  115 ). Since the detection section  117   b  does not detect a voltage supplied from the information display section  130  side, the detection section  117   b  does not output a facing device voltage detection result (e.g., a low-level signal is output). Since an adapter is not connected to the adapter terminal  143 , and hence the detection section  137   a  does not detect the voltage of an adapter, the detection section  137   a  does not output an adapter voltage detection result. Since the detection section  137   b  does not detect a voltage supplied from the input operation section  110 , during the battery charging operation for the battery section  119 , performed by the adapter  200 , the detection section  137   b  does not output the facing device voltage detection result. However, after that, the detection section  137   b  detects the voltage of the adapter  200  connected to the input operation section  110 , during the battery charging operation for the battery section  139 , and hence the detection section  137   b  outputs the facing device voltage detection result to the switching control section  135 . 
         [0160]    The power source control section  118  does not output the charging status notification while the adapter  200  is charging the battery section  119 . In addition, the power source control section  118  detects the completion of the battery charging operation for the battery section  119 . In addition, since the battery section  119  is not being charged after the completion of the battery charging operation for the battery section  119 , the power source control section  118  outputs the charging status notification to the switching control section  115 . In addition, the power source control section  118  notifies the control section  114  of a notification relating to the remaining battery level of the battery section  119 . 
         [0161]    The power source control section  138  does not output the charging status notification while the adapter  200  is charging the battery section  139 . In addition, the power source control section  138  detects the completion of the battery charging operation for the battery section  139 . In addition, since the battery section  139  is not being charged after the completion of the battery charging operation for the battery section  139 , the power source control section  138  outputs the charging status notification to the switching control section  135 . In addition, the power source control section  138  notifies the control section  134  of a notification relating to the remaining battery level of the battery section  139 . 
         [0162]    While the adapter  200  is charging the battery section  119 , the control section  114  controls the switch  122   c  so that the switch  122   c  is in an on-state. After that, while the adapter  200  is charging the battery section  139 , the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state, as illustrated in  FIG. 11 . 
         [0163]    While the adapter  200  is charging the battery section  119 , the switching control section  115  controls the switches  122   a  and  122   b  so that the switches  122   a  and  122   b  are in the off-states. After that, while the adapter  200  is charging the battery section  139 , the switching control section  115  controls the switches  122   a  and  122   b  that the switch  122   a  is in the on-state and the switch  122   b  is in the off-state, as illustrated in  FIG. 11 . 
         [0164]    While the adapter  200  is charging the battery section  119 , the control section  134  controls the switches  142   c  so that the switches  142   c  is in an on-state. After that, while the adapter  200  is charging the battery section  139 , the control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state, as illustrated in  FIG. 11 . 
         [0165]    While the adapter  200  is charging the battery section  119 , the switching control section  135  controls the switches  142   a  and  142   b  so that the switches  142   a  and  142   b  are in the off-states. After that, while the adapter  200  is charging the battery section  139 , the switching control section  135  controls the switches  142   a  and  142   b  so that the switch  142   a  is in an on-state and the switch  142   b  is in an off-state, as illustrated in  FIG. 11 . 
         [0166]    While the adapter  200  is charging the battery section  119 , the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the off-state. The switching control section  115  controls the switch  122   b  so that the switch  122   b  is in the off-state. The control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. The switching control section  135  controls the switch  142   a  so that the switch  142   a  is in an off-state. The switching control section  135  controls the switch  142   b  so that the switch  142   b  is in the off-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. Accordingly, while the battery section  119  is being charged, the electric power of the adapter  200  connected to the adapter terminal  123  is supplied to the battery section  119  through the switch  122   c  and the power source control section  118 . In addition, while the battery section  119  is being charged, by putting the switch  122   b  into the off-state, a countercurrent and a short circuit are prevented from occurring and the safety is ensured. 
         [0167]    While the battery section  139  is being charged, the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the on-state, as illustrated in  FIG. 11 . The switching control section  115  controls the switch  122   b  so that the switch  122   b  is in the off-state. The control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. The switching control section  135  controls the switch  142   a  so that the switch  142   a  is in the on-state. The switching control section  135  controls the switch  142   b  so that the switch  142   b  is in the off-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. Accordingly, while the battery section  139  is being charged, the electric power of the adapter  200  connected to the adapter terminal  123  is supplied to the battery section  139  through the switch  122   a , the contact terminals  116   a  and  136   a , the switches  142   a  and  142   c , and the power source control section  138 . In addition, while the battery section  139  is being charged, by putting the switch  142   b  into the off-state, a countercurrent and a short circuit are inhibited or prevented from occurring and the safety is ensured. 
         [0168]    Here, the charging status notifications that the power source control sections  118  and  138  provide may be given constantly or periodically, for example. In addition, the charging status notifications may be provided in response to requests from the control sections  114  and  134 . 
         [0169]      FIG. 12  illustrates the flow of a processing operation performed when the input operation section and the information display section are charged using the adapter connected to the input operation section according to the second embodiment. The processing operation illustrated in  FIG. 12  will be described in line with the step numbers of the sequence diagram, hereinafter. The execution of the following processing operation is started when one device connected to an adapter charges the device and a facing device. Here, while a case in which the input operation section  110  is connected to the adapter  200  will be described, a case in which the information display section  130  is connected to the adapter  200  is the same as the former case, and hence the descriptions thereof will be omitted. 
         [0170]    [Step S 11 ] The control section  114  starts charging the battery section  119  by using the adapter  200 . At this time, the control section  114  causes the switching control section  115  to control the switch  122   a  so that the switch  122   a  is in the off-state. In addition, the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. 
         [0171]    [Step S 12 ] When the battery charging operation for the battery section  119  is completed, the power source control section  118  switches a signal used for the charging status notification and notifies the switching control section  115  of the completion of the battery charging operation. In addition, by using the remaining battery level notification, the power source control section  118  notifies the control section  114  of the completion of the battery charging operation. When the switching control section  115  detects the charging status notification, the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the on-state. 
         [0172]    [Step S 13 ] The control section  114  controls the switching control section  115  to start supplying charging power for the battery section  139  by using the adapter  200  as a power source. At this time, the control section  114  causes the switching control section  115  to control the switches  122   a  and  122   b  so that the switch  122   a  is in the on-state and the switch  122   b  is in the off-state. In addition, the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. In addition, through the contact terminals  116   c  and  136   c , the control section  114  notifies the control section  134  of the start of the supply of electric power which uses the adapter  200  as a power source. 
         [0173]    [Step S 14 ] The control section  134  controls the power source control section  138  to start charging the battery section  139  by using the adapter  200  as a power source. At this time, the control section  134  causes the switching control section  135  to control the switch  142   a  so that the switch  142   a  is in the on-state. In addition, the control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. 
         [0174]    [Step S 15 ] When the battery charging operation for the battery section  139  is completed, the power source control section  138  switches a signal used for the charging status notification and notifies the switching control section  135  of the completion of the battery charging operation. In addition, by using the remaining battery level notification, the power source control section  138  notifies the control section  134  of the completion of the battery charging operation. 
         [0175]      FIG. 13  illustrates a battery power supply processing operation according to the second embodiment. In the embodiment, a battery power supply processing operation, in which, using the remaining battery charge of one (for example, the input operation section  110 ) of the input operation section  110  and the information display section  130  included in the mobile terminal device  100 , the other device is charged, may be performed. 
         [0176]      FIG. 13  illustrates the mobile terminal device  100  in which the battery section  139  included in the information display section  130  is being charged using the remaining battery charge of the battery section  119  included the input operation section  110 . In addition, at this time, neither the adapter terminal  123  included in the input operation section  110  nor the adapter terminal  143  included in the information display section  130  is connected to an adapter. 
         [0177]    As described above, the contact terminals  116   a ,  116   b , and  116   c  are connected to the contact terminals  136   a ,  136   b , and  136   c , respectively. Since neither of adapters is connected, and hence neither of the detection sections  117   a  and  137   a  detects the voltages of an adapter, neither of the detection sections  117   a  and  137   a  outputs an adapter voltage detection result. Since the detection section  117   b  does not detect a voltage supplied from the information display section  130 , the detection section  117   b  does not output a facing device voltage detection result. Since the detection section  137   b  detects the voltage of the battery section  119 , the detection section  137   b  outputs a facing device voltage detection result to the switching control section  135 . 
         [0178]    The power source control section  118  notifies the control section  114  of a notification relating to the remaining battery level of the battery section  119 . The power source control section  138  does not output the charging status notification while the battery section  139  is being charged. In addition, the power source control section  138  detects the completion of the battery charging operation for the battery section  139 . In addition, after the completion of the battery charging operation for the battery section  139 , the power source control section  138  outputs the charging status notification to the switching control section  135 . In addition, the power source control section  138  notifies the control section  134  of a notification relating to the remaining battery level of the battery section  139 . 
         [0179]    While the battery section  119  is charging the battery section  139 , the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state, as illustrated in  FIG. 13 . The switching control section  115  controls the switches  122   a  and  122   b  so that the switch  122   a  is in the off-state and the switch  122   b  is in the on-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. The switching control section  135  controls the switches  142   a  and  142   b  so that the switch  142   a  is in the on-state and the switch  142   b  is in the off-state. 
         [0180]    While the battery section  119  is charging the battery section  139 , the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the off-state, as illustrated in  FIG. 13 . The switching control section  115  controls the switch  122   b  so that the switch  122   b  is in the off-state. The control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. The switching control section  135  controls the switch  142   a  so that the switch  142   a  is in the on-state. The switching control section  135  controls the switch  142   b  so that the switch  142   b  is in the off-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. Accordingly, while the battery section  119  is charging the battery section  139 , the electric power of the battery section  119  is supplied to the battery section  139  through the switch  122   b , the contact terminals  116   a  and  136   a , the switches  142   a  and  142   c , and the power source control section  138 . In addition, while the battery section  119  is charging the battery section  139 , by putting the switch  142   b  into the off-state, a countercurrent and a short circuit are inhibited or prevented from occurring and the safety is ensured. 
         [0181]      FIG. 14  illustrates the flow of the battery power supply processing operation according to the second embodiment. The processing operation illustrated in  FIG. 14  will be described in line with the step numbers of the sequence diagram, hereinafter. The execution of the following processing operation is started when the remaining battery level of the other device falls. Here, while a case in which the remaining battery level of the input operation section  110  has room for use and the remaining battery level of the information display section  130  falls will be described, a case in which the remaining battery level of the information display section  130  has room for use and the remaining battery level of the input operation section  110  falls is the same as the former case, and hence the descriptions thereof will be omitted. 
         [0182]    [Step S 21 ] The control section  134  transmits a notification to the control section  114  through the contact terminals  136   c  and  116   c , the notification being used for confirming whether or not the information display section  130  can receive a supply of charging power, using the remaining battery charge of the battery section  119  as a power source, so as to charge the battery section  139 . 
         [0183]    Here, regarding whether or not to confirm the supply of charging power from the battery section  119  for the battery section  139 , for example, when a charging rate, which is the ratio of a currently remaining battery level to the remaining battery level of the battery section  139  at the time of full charge, is less than a specified ratio (for example, 25%), with respect to the remaining battery level of the battery section  139 , the supply of charging power may be confirmed. In addition, it may be determined whether or not to confirm the supply of charging power, using another criterion. 
         [0184]    As an example of the specified ratio, a threshold value used for a remaining battery level display shown in the information display section  130  may be used. Here, in the input operation section  110  and the information display section  130  according to the embodiment, it may be assumed that remaining battery level are displayed to indicate the individual remaining battery levels. In each of the devices that are the input operation section  110  and the information display section  130 , a remaining battery level display corresponding to the remaining battery level of the device (for example, a display where vertically long bars are horizontally aligned the number of which changes to any integer from among “zero” to “three”) is performed. 
         [0185]    For example, when the remaining battery level is more than or equal to 70% of the remaining battery level at the time of full charge, “three bars”, the maximum number of bars, are displayed on the remaining battery level display. When the remaining battery level is more than or equal to 20% of but less than 70% of the remaining battery level at the time of full charge, “two bars” are displayed on the remaining battery level display. When the remaining battery level is more than or equal to 10% of but less than 20% of the remaining battery level at the time of full charge, “one bar” is displayed on the remaining battery level display. When the remaining battery level is less than 10% of the remaining battery level at the time of full charge, “no bar” is displayed on the remaining battery level display. 
         [0186]    In such a case, when the remaining battery level of the battery section  139  in the information display section  130  is lower than “10%”, which is the lower threshold value adopted when “one bar” is displayed on the remaining battery level display, the information display section  130  may confirm with the input operation section  110  the supply of charging power from the battery section  119 . 
         [0187]    [Step S 22 ] On the basis of the notification relating to the remaining battery level, which the power source control section  118  provides, the control section  114  confirms the remaining level of the battery section  119 . If the remaining level of the battery section  119  is not enough to supply electric power to the battery section  139 , the control section  114  transmits an unavailable supply response, which indicates that the supply of electric power is not available. The supply response is provided to the control section  134  through the contact terminals  116   c  and  136   c . When the remaining battery level is enough to supply electric power to the battery section  139 , the processing operation can proceed to Step S 23 . 
         [0188]    Regarding whether or not the remaining battery level of the battery section  119  is enough to supply electric power to the battery section  139 , for example, when a charging rate, which is the ratio of a current remaining battery level to the remaining battery level of the battery section  119  at the time of full charge, is more than or equal to a specified ratio (for example, 50%), with respect to the remaining battery level of the battery section  119 , it is determined that the remaining battery level of the battery section  119  is enough to supply electric power to the battery section  139 . In addition, it may be determined whether or not the remaining battery level of the battery section  119  is enough, using another criterion. 
         [0189]    As an example of the specified ratio, in the same way as Step S 21 , a threshold value used for a remaining battery level display shown in the input operation section  110  may be used. For example, when the information display section  130  confirms with the input operation section  110  the supply of charging power from the battery section  119  to the battery section  139 , the control section  114  may determine whether or not the supply of charging power is performed, on the basis of whether the remaining battery level of the battery section  119  in the input operation section  110  is more than or equal to, or less than “70%”, which is the lower threshold value adopted when “three bars” are displayed on the remaining battery level display. At this time, when the remaining battery level of the battery section  119  is more than or equal “70%”, the control section  114  may perform the supply of charging power from the battery section  119 , and when the remaining battery level of the battery section  119  is less than “70%”, the control section  114  may not perform the supply of charging power from the battery section  119 . 
         [0190]    [Step S 23 ] The control section  114  transmits an available supply response, which indicates that electric power can be supplied using the battery section  119 , through the contact terminals  116   c  and  136   c.    
         [0191]    [Step S 24 ] The control section  134  transmits to the control section  114  through the contact terminals  136   c  and  116   c  a request relating to the start of the supply of charging power performed using the remaining battery charge of the battery section  119  as a power source. 
         [0192]    [Step S 25 ] The control section  114  controls the switching control section  115  to start supplying charging power for the battery section  139  by using the battery section  119  as a power source. At this time, the control section  114  causes the switching control section  115  to control the switches  122   a  and  122   b  so that the switches  122   a  is in the off-state and the switches  122   b  is in the on-state. In addition, the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. In addition, through the contact terminals  116   c  and  136   c , the control section  114  notifies the control section  134  of the start of the supply of charging power performed using the battery section  119  as a power source. 
         [0193]    [Step S 26 ] The control section  134  controls the power source control section  138  to start charging the battery section  139  by using the battery section  119  as a power source. At this time, by transmitting a control signal to the switching control section  135 , the control section  134  causes the switching control section  135  to control the switches  142   a  and  142   b  so that the switch  142   a  is in the on-state and the switch  142   b  is in the off-state. In addition, the control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. 
         [0194]    [Step S 27 ] The control section  114  monitors the remaining battery level notification provided by the power source control section  118 , which indicates the remaining battery level of the battery section  119 . In addition, when the remaining battery level of the battery section  119  becomes lower than a specified level, the control section  114  terminates the supply of charging power, performed using the battery section  119  as a power source. In this case, the control section  114  switches the control signal and notifies the switching control section  135  of the completion of the battery charging operation. In addition, through the contact terminals  116   c  and  136   c , the control section  114  transmits a notification relating to the completion of the supply of charging power performed using the battery section  119  as a power source. 
         [0195]    [Step S 28 ] When the battery charging operation for the battery section  139  is completed, the power source control section  138  switches a signal used for the charging status notification and notifies the switching control section  135  of the completion of the battery charging operation. In addition, in the battery power supply processing operation according to the embodiment, on the basis of whether or not the remaining battery level of the battery section  119  is enough to supply electric power to the battery section  139 , it is determined whether or not the battery power supply is performed. However, the determination operation is not limited to the example but the determination may be performed using another determination criterion such as the comparison of the remaining battery level of the battery section  119  with the remaining battery level of the battery section  139 , or the like. 
         [0196]    In addition, in the embodiment, for example, when the remaining battery level of the battery section  119  becomes lower than a specified level, the battery power supply for the battery section  139  is terminated. However, the termination of the battery power supply is not limited to the example but, for example, the termination may be performed using another determination criterion such as the case in which, when the remaining battery level of the battery section  119  becomes equal to the remaining battery level of the battery section  139 , the battery power supply is terminated, or the like. 
         [0197]      FIG. 15  illustrates a processing operation for battery charging according to the second embodiment. In the embodiment, when, using an adapter terminal arranged in one of the input operation section  110  and the information display section  130  included in the mobile terminal device  100  (e.g., the adapter terminal  123  arranged in the input operation section  110 ), the battery sections  119  and  139  are charged. Further, example embodiments also include a battery charging operation where one device, the remaining battery level of which is less than that of the other device, is charged. 
         [0198]    As illustrated in  FIG. 15 , the adapter  200  is connected to the adapter terminal  123  in the input operation section  110 .  FIG. 15  illustrates the mobile terminal device  100  in which the battery section  139  is charged using the adapter  200 . In addition, an adapter is not connected to the adapter terminal  143  in the information display section  130 . 
         [0199]    As described above, the contact terminals  116   a ,  116   b , and  116   c  are connected to the contact terminals  136   a ,  136   b , and  136   c , respectively. The detection section  117   a  detects the voltage of the adapter  200  connected to the adapter terminal  123 , and outputs the adapter voltage detection result to the control section  114  and the switching control section  115 . Since the detection section  117   b  does not detect a voltage supplied from the information display section  130  side, the detection section  117   b  does not output a facing device voltage detection result. Since an adapter is not connected to the adapter terminal  143 , and hence the detection section  137   a  does not detect the voltage of an adapter, the detection section  137   a  does not output an adapter voltage detection result. While the detection section  137   b  detects the voltage of the adapter  200 , connected to the input operation section  110 , during the preferential battery charging operation for the battery section  139 , the detection section  137   b  outputs the facing device voltage detection result to the switching control section  13 . However, after that, since the detection section  137   b  does not detect a voltage supplied from the input operation section  110 , during the battery charging operation for the battery section  119 , the detection section  137   b  does not output the facing device voltage detection result. 
         [0200]    Since the battery section  119  is not being charged during the battery charging operation for the battery section  139 , performed by the adapter  200 , the power source control section  118  outputs the charging status notification to the switching control section  115 . In addition, after that, the power source control section  118  does not output the charging status notification while the battery section  119  is being charged. In addition, the power source control section  118  notifies the control section  114  of a notification relating to the remaining battery level of the battery section  119 . 
         [0201]    The power source control section  138  does not output the charging status notification while the adapter  200  is charging the battery section  139 . In addition, when the battery charging operation for the battery section  139  is completed, the power source control section  138  detects the completion of the battery charging operation for the battery section  139 . In addition, since the battery section  139  is not being charged while the battery section  119  is being charged, the power source control section  138  outputs the charging status notification to the switching control section  135 . In addition, the power source control section  138  notifies the control section  134  of a notification relating to the remaining battery level of the battery section  139 . 
         [0202]    While the adapter  200  is charging the battery section  139 , the control section  114  controls the switch  122   c  so that the switch  122   c  is in the off-state, as illustrated in  FIG. 15 . After that, while the adapter  200  is charging the battery section  119 , the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. 
         [0203]    While the adapter  200  is charging the battery section  139 , the switching control section  115  controls the switches  122   a  and  122   b  so that the switch  122   a  is in the on-states and the switch  122   b  is in the off-states, as illustrated in  FIG. 15 . After that, while the adapter  200  is charging the battery section  119 , the switching control section  115  controls the switches  122   a  and  122   b  that the switches  122   a  and  122   b  are in the off-state. 
         [0204]    While the adapter  200  is charging the battery section  139 , the control section  134  controls the switches  142   c  so that the switches  142   c  is in the on-state, as illustrated in  FIG. 15 . While the adapter  200  is charging the battery section  119  after the power source control section  138  detects the completion of the battery charging operation for the battery section  139 , the control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. 
         [0205]    While the adapter  200  is charging the battery section  139 , the switching control section  135  controls the switches  142   a  and  142   b  so that the switch  142   a  is in the on-state and the switch  142   b  is in the off-state, as illustrated in  FIG. 15 . After that, while the adapter  200  is charging the battery section  119 , the switching control section  135  controls the switches  142   a  and  142   b  so that the switches  142   a  and  142   b  are in the off-states. 
         [0206]    While the adapter  200  is charging the battery section  139 , the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the on-state, as illustrated in  FIG. 15 . The switching control section  115  controls the switch  122   b  so that the switch  122   b  is in the off-state. The control section  114  controls the switch  122   c  so that the switch  122   c  is in the off-state. The switching control section  135  controls the switch  142   a  so that the switch  142   a  is in the on-state. The switching control section  135  controls the switch  142   b  so that the switch  142   b  is in the off-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. Accordingly, while the battery section  139  is being charged, the electric power of the adapter  200  connected to the adapter terminal  123  is supplied to the battery section  139  through the switch  122   a , the contact terminals  116   a  and  136   a , the switches  142   a  and  142   c , and the power source control section  138 . In addition, while the battery section  139  is being charged, by putting the switch  142   b  into the off-state, a countercurrent and a short circuit are inhibited or prevented from occurring and the safety is ensured. In addition, even though the remaining battery level of the battery section  119  is not enough, by putting the switch  122   c  into the off-state while the battery section  139  is being charged, an electric current between the adapter  200  and the battery section  119  is shut off, and the electric power of the adapter  200  is supplied to the battery section  139 . 
         [0207]    While the battery section  119  is being charged, the switching control section  115  controls the switch  122   a  so that the switch  122   a  is in the off-state. The switching control section  115  controls the switch  122   b  so that the switch  122   b  is in the off-state. The control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. The switching control section  135  controls the switch  142   a  so that the switch  142   a  is in the off-state. The switching control section  135  controls the switch  142   b  so that the switch  142   b  is in the off-state. The control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. Accordingly, while the battery section  119  is being charged, the electric power of the adapter  200  connected to the adapter terminal  123  is supplied to the battery section  119  through the switch  122   c  and the power source control section  118 . In addition, while the battery section  119  is being charged, by putting the switch  122   b  into the off-state, a countercurrent and a short circuit are inhibited or prevented from occurring and the safety is ensured. 
         [0208]      FIG. 16  illustrates the flow of the processing operation for battery charging according to the second embodiment. The processing operation illustrated in  FIG. 16  will be described in line with the step numbers of the sequence diagram, hereinafter. The execution of the following processing operation is started when one device connected to an adapter charges the device and a facing device and the remaining battery level of the facing device falls. Here, while a case in which the adapter  200  is connected to the input operation section  110  and the remaining battery level of the information display section  130  falls will be described, a case in which an adapter is connected to the information display section  130  and the remaining battery level of the input operation section  110  falls is the same as the former case, and hence the descriptions thereof will be omitted. 
         [0209]    [Step S 31 ] The control section  134  transmits a battery charge request to the control section  114  through the contact terminals  136   c  and  116   c , the battery charge request being used for requesting to charge the battery section  139  using the adapter  200 , connected to the adapter terminal  123 , as a power source. In addition, the battery charge request includes information indicating the remaining battery level of the battery section  139 . 
         [0210]    [Step S 32 ] On the basis of the information indicating the remaining battery level of the battery section  139 , included in the battery charge request that the control section  134  gives notice of, the control section  114  confirms the remaining level of the battery section  139 . In addition, on the basis of the notification relating to the remaining battery level, which the power source control section  118  gives notice of, the control section  114  confirms the remaining level of the battery section  119 . Next, when, by comparing the remaining battery level of the battery section  119  with the remaining battery level of the battery section  139 , it is determined that the remaining battery level of the battery section  139  is greater than or equal to that of the battery section  119 , the control section  114  transmits an unavailable battery charge supply response, which indicates that the preferential battery charging operation is not available, to the control section  134  through the contact terminals  116   c  and  136   c  while the control section  114  does not perform the preferential battery charging operation. After that, as illustrated in  FIGS. 11 and 12 , in the mobile terminal device  100 , after the battery section  119  is charged first, the battery section  139  is charged. When the remaining battery level of the battery section  139  is low, the processing operation proceeds to Step S 33 . 
         [0211]    [Step S 33 ] The control section  114  controls the switching control section  115  to start supplying charging power for the battery section  139  by using the adapter  200  as a power source. At this time, the control section  114  causes the switching control section  115  to control the switches  122   a  and  122   b  so that the switch  122   a  is in the on-state and the switch  122   b  is in the off-state. In addition, the control section  114  controls the switch  122   c  so that the switch  122   c  is in the off-state. In addition, through the contact terminals  116   c  and  136   c , the control section  114  notifies the control section  134  of the start of the battery charging operation that uses the adapter  200  as a power source. 
         [0212]    [Step S 34 ] The control section  134  controls the power source control section  138  to start charging the battery section  139  by using the adapter  200  as a power source. At this time, the control section  134  causes the switching control section  135  to control the switch  142   a  so that the switch  142   a  is in the on-state. In addition, the control section  134  controls the switch  142   c  so that the switch  142   c  is in the on-state. 
         [0213]    [Step S 35 ] When the battery charging operation for the battery section  139  is completed, the power source control section  138  switches a signal used for the charging status notification and notifies the switching control section  135  of the completion of the battery charging operation. In addition, by using the remaining battery level notification, the power source control section  138  notifies the control section  134  of the completion of the battery charging operation. 
         [0214]    Here, regarding the determination of whether or not the battery charging operation for the battery section  139  is completed, when the remaining battery level of the battery section  139  reaches a specified remaining battery level (for example, a remaining battery level corresponding to 80% of the remaining battery level of the battery section  139  at the time of full charge), the power source control section  138  may determine that the battery charging operation for the battery section  139  is completed. The charge efficiencies of some batteries decrease when the remaining battery levels thereof approach full charge levels to some extent (for example, more than or equal to 70% of full charge levels thereof). On the basis of the fact, when the remaining battery level does not reach the full charge level but reaches a specified remaining battery level (for example, 80% of the full charge level), a high electric charge effect can be obtained by completing the battery charging operation for the battery section  139  and charging the battery section  119 . 
         [0215]    [Step S 36 ] The control section  134  transmits a battery charge completion notification to the control section  114  through the contact terminals  136   c  and  116   c , the battery charge completion notification being used for giving notice of the completion of the battery charging operation for the battery section  139 . 
         [0216]    [Step S 37 ] The control section  114  starts charging the battery section  119  by using the adapter  200  as a power source. At this time, the control section  114  causes the switching control section  115  to control the switch  122   a  so that the switch  122   a  is in the off-state. In addition, the control section  114  controls the switch  122   c  so that the switch  122   c  is in the on-state. 
         [0217]    [Step S 38 ] When the battery charging operation for the battery section  119  is completed, the power source control section  118  switches a signal used for the charging status notification and notifies the switching control section  115  of the completion of the battery charging operation. In addition, by using the remaining battery level notification, the power source control section  118  notifies the control section  114  of the completion of the battery charging operation. 
         [0218]    In addition, in the battery charging operation according to the embodiment, for example, by comparing the remaining battery level of the battery section  119  with the remaining battery level of the battery section  139 , it is determined whether or not the battery charging operation is performed. However, the determination operation is not limited to the example but the determination may be performed using another determination criterion such as the comparison of the charging rate of the battery section  119  with the charging rate of the battery section  139 , or the like. 
         [0219]    As described above, according to the second embodiment, the individual remaining battery levels of the separable input operation section  110  and the separable information display section  130 , arranged in the mobile terminal device  100 , can be adjusted between both devices. 
         [0220]    In addition, if one device is connected to an adapter, the other device can also be charged. Therefore, the time and effort of the user can be simplified when a battery charging operation is performed. In addition, by connecting the adapter to one of the input operation section  110  and the information display section  130 , which are in the integrated state, both devices can be charged. 
         [0221]    In addition, for example, in the case in which, using battery power, the user uses the mobile terminal device  100  in the mechanically separated state, at the time that a battery in one device has been drained first, such as the case in which the device is mainly used, or the like, if a battery in the other device has some energy left, by using the remaining battery charge of the battery that has some energy left, the battery in the device that has been drained can be charged. Accordingly, the operation time of the device, the battery of which has been drained, can be extended, and the battery operation time of the entire mobile terminal device  100  can be lengthened. 
         [0222]    In addition, in the case in which the input operation section  110  and the information display section  130 , which are in the integrated state, are charged using the adapter, when there is an imbalance between the remaining battery levels of both devices, one device, the remaining battery level of which is lower, can be charged. 
         [0223]    In addition, since a connection line is shared through which the devices supply electric power to each other, contacts and connection lines arranged between the input operation section  110  and the information display section  130  in the mobile terminal device  100  can be simplified. Here, while the embodiment is described by citing the mobile terminal device, the mobile terminal device is just an example, and the techniques described in the embodiment can be applied to all kinds of separable electronic devices. Examples of the electronic devices that the techniques can be applied to include a mobile phone, a portable TV terminal, a portable video game player, an electronic dictionary device, a notebook computer, and PDA or the like, which can be individually separated into main bodies and cradles. However, Examples of the electronic devices are not limited to these devices mentioned above. 
         [0224]    In addition, for example, the cradle may include a function used for charging the main body, a function used for reading and writing information from and into the main body by communicating with the main body, and a function used for displaying the information read out. As mentioned above, the disclosed electronic devices and the disclosed power source control devices are described on the basis of the embodiment illustrated. However, the above descriptions are just for presenting the principle of the present invention. The disclosed techniques can be variously modified and changed by those skilled in the art, and are not limited to the accurate configurations and the application examples, illustrated and described above. In addition, the configurations of individual sections can be replaced with arbitrary configurations having the same functions. In addition, another arbitrary constituent object or another arbitrary process may be added to the disclosed techniques. In addition, more than one arbitrary configuration of the embodiment mentioned above may be combined into the disclosed techniques. In addition, all modifications and equivalents corresponding to the disclosed techniques are regarded as within the scope of the present invention, based on the appended claims or the equivalents thereof. 
         [0225]    All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention.