Abstract:
An electronic device includes a power supply circuit selectively providing an external power source or an internal power source, a first part determining whether the external power source is selected, a second part detecting a type of a functional unit used in the electronic device, and a third part which controls to supply the functional unit with electricity from one of the external and internal power sources on the basis of determination results obtained by the first and second parts.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to electronic devices, and more particularly to an electronic device supplied with driving power from an external power source or a built-in battery which is generally detachable. 
     Recently, there has been considerable activity in the development of portable electronic devices such as portable information processing devices, for example, portable laptop computers which can be easily carried. 
     The portable computer is supplied with power from a battery. In order to improve the portability, it is required to miniaturize the battery and reduce consumption power. 
     2. Description of the Related Art 
     A conventional electronic device is equipped with a suspend/resume function of supplying power to the minimum parts of the device and breaking a supply of power to the other parts thereof so that power consumption can be reduced. 
     The suspend/resume function is initiated when a suspend/resume button provided to the body of the electronic device is operated. Then, data in progress is saved and power is supplied to the minimum parts necessary to hold the data thus saved. The other parts of the device are in a paused state, so called, suspended state. When the suspend/resume button is operated in the suspended state, the saved data is restored and the original state immediately prior to the suspended state is retrieved. 
     The suspended state is initiated at the time of carrying the electronic device, so that a reduced amount of power can be consumed in the device. 
     Generally, the conventional portable computer is designed to handle a functional unit or a module such as a LAN card or a modem card. A connector connected to a telephone line connected to a telephone network or a LAN line connected to a LAN is connected to a modular jack of the computer. In a place in which the connector is available, commercial power source is also available. 
     The functional unit such as a modem module of a card type (also referred to as a modem card) or a LAN module of a card type (also referred to as a LAN module) can be driven by the built-in battery without a supply of electricity from an external power source obtained via an AC-DC adapter. Hence, even when a supply of power from the commercial source is available, the user is liable to use the built-in battery rather than the commercial source. In this case, the battery is not charged and the driving capability thereof is reduced because the AC-DC adapter is not connected to the electronic device and a supply of power therefrom does not take place. 
     Particularly, the LAN module has a comparatively high data transmission rate and thus consumes a large amount of energy. Thus, the driving capability of the battery is greatly reduced. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide an electronic device in which the above disadvantages are eliminated. 
     A more specific object of the present invention is to provide an electronic device in which consumption of power of the built-in battery which is generally detachable. 
     The above objects of the present invention are achieved by an electronic device comprising: a power supply circuit selectively providing an external power source or an internal power source; a first part determining whether the external power source is selected; a second part detecting a type of a functional unit used in the electronic device; and a third part which controls to supply the functional unit with electricity from one of the external and internal power sources on the basis of determination results obtained by the first and second parts. 
     A further object of the present invention is to provide a method of controlling a supply of electricity to-a functional unit in which the above-mentioned disadvantages are eliminated. 
     This object of the present invention is achieved by a method of controlling a supply of electricity to a functional module detachably attached to an electronic device, said method comprises the steps of: determining whether an external power source is selected; detecting a type of a functional unit used in the electronic device; a third part which controls to supply the functional unit with electricity from the external power source or an internal power source on the basis of determination results obtained by the first and second parts. 
     According to the present invention, the electricity can be supplied from the external power source to the functional module of the given type when the external power is available. Hence, when the internal power source is selected, the functional module is not supplied with electricity therefrom. Hence, it is possible to prevent power from being consumed by the functional module when the external power source is not selected. Of course, as will be seen from the following detailed description, the functional module can be supplied with electricity from the internal power source in response to a given instruction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a portable electronic device (portable information processing device) according to an embodiment of the present invention; 
     FIG. 2 is a perspective view of a bottom surface of the portable electronic device shown in FIG. 1; 
     FIG. 3 is a block diagram of the portable electronic device according to the embodiment of the present invention; 
     FIG. 4 is a flowchart of a module connecting process performed in the embodiment shown in FIG. 3; 
     FIG. 5 is a flowchart of a process of a power source connection control circuit used in the embodiment of the present invention; and 
     FIG. 6 is a timing chart of an operation performed at the time of activating and deactivating a module. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view of a portable computer which is an electronic device according to an embodiment of the present invention. 
     An electronic device  100  is a pen-input type personal computer. A display part  102  and a state indication part  103  are provided to a display surface  101  of the electronic device  100 . The display part  102  is arranged to the approximately whole display surface  101 . The display part  102  includes a liquid crystal display  104  and a touch panel  105 . Graphics information such as figures and characters is displayed on the liquid crystal display  104 . The touch panel  105  is used to input information. 
     The state indication part  103  includes a plurality of LEDs  103   a - 103   d , which indicate the respective operation states of the device, for example, the ON/OFF state of an external power source and the ON/OFF state of charging a battery, built in the electronic device  100  in a detachable fashion. 
     To a right side surface  110  of the electronic device  100 , there are provided an AC-DC adapter connection port  111 , a USB (Universal Serial Bus) port  112 , a communication connector port  113 , a PC card slot  114 , and a pen inlet port  115 . An AC-DC adapter  116  is connected to the AC-DC adapter connection port  111 , and an external power source is available via the AC-DC adapter  116 . 
     The USB port  112  is a port which conforms to the USB standards. A USB cable  117  is connected to the USB port  112 , so that a peripheral device can be connected to the electronic device  100 . 
     The communication connector port  113  conforms to the RJ 11 . A connector  118  of telephone line or a LAN line which conforms to the RJ 11  can be connected to the communication connector port  113 . 
     The PC card slot  114  conforms to the PCMCIA standard. A PC card  119  which conforms to the PCMCIA standard can be inserted into the PC card slot  114 . 
     A pen  120  can be inserted into and detached from the pen inlet port  115  and is used to operate the touch panel  104 . 
     A DC contact  112  and an expansion connector  113  are provided to a lower surface  121  of the electronic device  100 . The DC contact  122  is connected to a DC power source when an expanded device (not shown) is connected to the electronic device  100 . The expanded connector  113  is used to receive signals from the expanded device and output signals thereto. 
     FIG. 2 is a perspective view of the back surface of the electronic device  100 . As shown in FIG. 2, a battery pack attaching part  131  and a battery pack lock  132  are provided to a back surface  130  of the electronic device  100 . 
     A battery pack  133  is attached to the battery pack attaching part  131 . When the battery pack  133  is attached to the battery pack attaching part  133 , the battery lock  132  locks the battery pack  133 , which can be detached from the battery pack attaching part  133  by unlocking the battery lock  132 . 
     A suspend/resume button  141  is arranged on an upper surface  140  of the electronic device  100  and is used to indicate a suspend/resume function. 
     To a left side surface  150  of the electronic device  100 , there are provided a IrDA port  151 , a microphone jack  152 , a headphone jack  153  and a speaker  154 . The IrDA port  151  is a communication port which conforms to the IrDA standard. The electronic device  100  can communicate with another device which has an IrDA port conforming to the IrDA standard. 
     A voice signal can be applied to the microphone jack  153 . A voice signal is output from the speaker  154 . 
     A description will now be given of an internal structure of the electronic device  100  with reference to FIG. 3, in which parts that are the same as those shown in FIGS. 1 and 2 are given the same reference numbers. 
     The electronic device  100  includes a CPU (controller)  161 , a memory  162 , a graphics LSI  163 , bridge circuits  164  and  165 , a PC card controller  166 , an IrDA controller  167 , a PCI bus  168 , a ROM  169 , and ISA bus  170 , a sound controller  171 , a power source connection control circuit  172 , a power supply control circuit  173 , a power supply circuit  174 , a state setting circuit  175 , a bus connection control part  176 , one or a plurality of modules  177  and an HDD (Hard Disk Drive)  178 . 
     The CPU  162  executes a process in accordance with programs stored in the ROM  169  and the HDD  178 . The memory  162  is used as a working area of the CPU  161 . 
     The graphics LSI device  163  executes graphics processing. The bridge circuit  164  connects the CPU  161 , the memory  162  and the graphics LSI device  163  to the PCI bus  168 . 
     The bridge circuit  165  connects the PCI bus  168  and the ISA bus  170 . The sound controller  171  and the touch panel  105  are connected to the ISA bus  170 . The microphone jack  152 , the headphone jack  153  and the speaker  154  are connected to the sound controller  171 , which performs a variety of voice processing. 
     The USB port  112  is connected to the bridge circuit  165 , which makes a connection with a device which conforms to the USB standard. 
     The power source connection control circuit  172  is connected to the PCI bus  168 , and controls the power supply control circuit  173  and the bus connection control part  176  in response to a power on instruction supplied via the PCI bus  168 , as will be described later. Further, the circuit  172  controls a set/reset operation on each of the modules  177 . 
     The power supply control circuit  173  includes power supply control circuits  173 -1- 173 - n  respectively provided to modules and circuits. The circuits  173 -1- 173 - n  are connected to the corresponding modules and circuits, and are turned on or off in response to power supply control signals a- 1 -a- n  from the power source connection control circuit  172 . Hence, the modules and the circuits are supplied with electricity or not. 
     The bus connection control part  176  is connected between the modules  177  and the PCI bus  168 , and connects or disconnects the modules  177  to or from the PCI bus  168  in response to a bus connection control signal supplied form the power source connection control circuit  172 . 
     The state setting circuit  175  includes a power source state register  175   a  and a module register  175   b . A flag is set in the power source state register  175   a , and indicates whether electricity is supplied from an internal power source of the battery pack  133  or an external power source of the AC-DC adapter  116 . A flag is set in the module register  175   b , and indicates whether the module  177  connected to the electronic device  100  is a LAN module or a modem module. 
     At the time of activating the electronic device  100 , the power source state register  175   a  and the module register  175   b  of the state setting circuit  175  are referred to by the BIOS, and the power source connection control circuit  172  is thus controlled. 
     FIG. 4 is a flowchart of a connecting process which is carried out at the time of activating the electronic device  100 . A module connecting process is carried out each time the electronic device  100  is activated. That is, the module connecting process is carried out at the time of the power on or the suspend/resume. When the power on or resume is instructed and the activating process is executed, the BIOS or the CPU  161  refers to the module register  175   b  of the module register  175   b  and determines whether the connected module  177  is a LAN module (LAN card) or not (step S 1 - 1 ). In other words, this step is intended to detect the type of the functional unit attached to the electronic device  100 . 
     If it is determined that the connected module  177  is a LAN module, the CPU  161  refers to the register  175   a  of the state setting circuit  175 , and determines whether the electricity is supplied from the external power source, that is, that from the AC-DC adapter  116  or the internal power source of the battery pack  133  (step S 1 - 2 ). 
     When the result of step S 1 - 2  shows that the electricity is supplied from the AC-DC adapter  116 , the power on instruction directed to the LAN module is issued to the power source connection control circuit  172  (step S 1 - 3 ). 
     When it is determined at step S 1 - 2  that the electricity is supplied from the battery pack  133 , the process is ended without issuing the power instruction directed to the module  177 . 
     At step S 1 - 1 , the register  175   b  of the state setting circuit  175  is referred to and it is determined whether the connected module  177  is a modem module or not (step S 1 - 4 ). 
     When the result of step S 1 - 4  shows that the connected module  177  is a modem module, the register  175   a  of the state setting circuit  175  is referred to and it is determined whether the electricity is supplied from the external power source, that is, from the AC-DC adapter  116  or the internal power source from the battery pack  133  (step S 1 - 5 ). 
     When it is determined at step S 1 - 5  that the electricity is supplied from the AC-DC adapter  116 , the CPU  161  issues the power on instruction directed to the model module to the power source connection control circuit  172  (step S 1 - 6 ). 
     When it is determined at step S 1 - 5  that the electricity is supplied from the battery pack  133 , the CPU  161  does not issue the power on instruction directed to the module  177  and ends the process. 
     A description will now be given of a process performed by the power source connection control circuit  172  with reference to FIG.  5 . 
     The power source connection control circuit  172  monitors receipt of the power on instruction directed to the LAN module (step S 2 - 1 ). When the power on instruction directed to the LAN module is received, the power source connection control circuit  172  turns on the power supply control circuit  173 -1 provided to the LAN module (step S 2 - 2 ). When the power supply control circuit  173 -1 is turned on at step S 2 - 2 , the LAN module connected as the module  177  is supplied with electricity. 
     When the power supply control circuit  173 -1 provided to the LAN module is turned on at step S 2 - 2  and electricity is started to be supplied thereto, the power source connection control circuit  172  turns on the bus connection control circuit  176  (step S 2 - 3 ). When the bus connection control circuit  176  is turned on, the module  177  and the PCI bus  178  are connected together. 
     When the module  177  and the PCI bus  178  are connected at step S 2 - 3 , the power source connection control circuit  172  supplies the set signal to the module  177 , which is thus switched to the set state (step S 2 - 4 ). 
     If the power on instruction received at step S 2 - 1  is not the power on instruction directed to the LAN module, the power source connection control circuit  172  determines that the power on instruction received at step S 2 - 1  is directed to the modem module (step S 2 - 5 ). 
     When it is determined at step S 2 - 5  that the power on instruction received is directed to the modem module, the power source connection control circuit  172  turns on the power supply control circuit  173 -2 provided to the modem module (step S 2 - 6 ). When the circuit  173 -2 provided to the LAN module is turned on at step S 2 - 6 , electricity is supplied to the modem module connected as the module  177 . 
     When the power supply control circuit  173 -2 provided to the modem module is turned on at step S 2 - 6  and electricity is supplied thereto, the power source connection control circuit  172  executes step S 2 - 3  at which the module  177  and the PCI bus  178  are connected. 
     When the module  177  and the PCI bus  178  are connected at step S 2 - 3 , the power source connection control circuit  172  supplies the set signal to the module  177  at step S 2 - 4 , so that the module  177  is switched to the set state. 
     FIG. 6 is a timing chart of the module connection process carried out in the electronic device  100 . More particularly, FIG.  6 (A) shows power on to the module, FIG.  6 (B) shows the state of the connection between the PCI bus  168  and the module  177  in the bus connection control part  176 , and FIG.  6 (C) shows the set/reset state of the module  177 . 
     Referring to FIG. 6, when the AC-DC adapter  116  is connected to the AC-DC adapter port  111  and electricity is externally supplied from the AC-DC adapter  116 , the power supply circuit  174  detects power on of the external power source. Then, electricity is supplied to the module  177  at time t 1  by the processes shown in steps S 2 - 2  and S 2 - 6  shown in FIG.  5 . 
     After electricity is supplied to the module  177  at time t 1 , the bus connection control part  176  is controlled by step S 2 - 3  shown in FIG. 5, and the module  177  is connected to the PCI bus  168  at time t 2 . 
     Thereafter, the reset signal is supplied to the module  177  from the power source connection control circuit  172  by the process of step S 2 - 4 . Then, the module  177  is reset at time t 3  and becomes operable. 
     At the time of power off, the module  177  is released from the set state at time t 4 , and the module  177  is disconnected from the PCI bus  178  by the bus connection control part  176  at time t 5 . Then, the electricity supplied to the module  177  by the power supply control circuit  172  is stopped. 
     Hence, it is possible to avoid occurrence of a situation in which the module  177  that is in the set state (operable state) is abruptly connected to the PCI bus  178  and to prevent another operation on the PCI bus  178  from being affected. 
     According to the embodiment of the present invention described above, a supply of power or electricity to the module  177  is controlled by determining, at the time of activating a given process such as power on or resume, whether electricity is supplied from the battery pack  133  from the external power source via the AC-DC adapter  116 . Hence, while the electronic device  100  is being driven, the supply of power to the module  177  is stopped and power consumed in the electronic device  100  can be reduced. 
     The present invention is not limited to the specifically disclosed embodiment and variations and modifications may be made without departing from the scope of the present invention.