Power supplying system, electronic apparatus, and power supplying method

Abstract

There are provided a power supplying system, an electronic apparatus, and a power supplying method capable of surely preventing an abnormal end even in a case where supply of external power is disconnected in an apparatus having no battery with a valid voltage. The supply system includes a first power feed unit (11) that preferentially outputs external power rather than internal power from a first battery (12) in an electronic apparatus (10), a second power feed unit (21) that preferentially outputs the external power rather than internal power from a second battery (22) in a connection apparatus (20), an external power feed connection unit (external power feed connection path (L3)) that connects an external power feed path (L1) to the first power feed unit (11) and an external power feed path (L2) to the second power feed unit (21), a selection unit (13) that selects one of the first power feed unit (11) and the second power feed unit (21), and a control unit (15) that causes the selection unit (13) to select a power feed unit that receives the internal power between the first power feed unit (11) and the second power feed unit (21).

What is claimed is: 
     
         1 . A power supplying system including an electronic apparatus and a connection apparatus connectable to the electronic apparatus, the power supplying system comprising:
 a first power feed unit that is provided in the electronic apparatus, is capable of receiving internal power from a first battery in the electronic apparatus and of receiving external power, and preferentially outputs the external power rather than the internal power from the first battery;   a second power feed unit that is provided in the connection apparatus, is capable of receiving internal power from a second battery in the connection apparatus and of receiving the external power, and preferentially outputs the external power rather than the internal power from the second battery;   an external power feed connection unit that connects a power feed path of the external power to the first power feed unit and a power feed path of the external power to the second power feed unit;   a selection unit that selects one of the first power feed unit and the second power feed unit as a supplying source of use power of the electronic apparatus; and   a control unit that causes the selection unit to select a power feed unit that receives the internal power between the first power feed unit and the second power feed unit.   
     
     
         2 . The power supplying system according to  claim 1 ,
 wherein the first power feed unit preferentially outputs power with a higher voltage between the internal power from the first battery and the external power to the selection unit, and   wherein the second power feed unit preferentially outputs power with a higher voltage between the internal power of the second battery and the external power to the selection unit.   
     
     
         3 . The power supplying system according to  claim 1 ,
 wherein the control unit has a determination unit that determines presence or absence of the first battery and the second battery with a valid voltage and provides an instruction of the selection to the selection unit based on a result of the determination by the determination unit.   
     
     
         4 . The power supplying system according to  claim 3 ,
 wherein the control unit causes the selection unit to select a power feed unit set in advance between the first power feed unit and the second power feed unit in a state where both the first battery and the second battery have the valid voltage.   
     
     
         5 . The power supplying system according to  claim 3 ,
 wherein the control unit causes the selection unit to select a power feed unit connected to the battery with the valid voltage between the first power feed unit and the second power feed unit in a state where one of the first battery and the second battery has the valid voltage.   
     
     
         6 . The power supplying system according to  claim 1 ,
 wherein the electronic apparatus and the connection apparatus are respectively provided with an external power input terminal capable of receiving the external power from an external power supply,   wherein the first power feed unit is connected to the external power input terminal provided in the electronic apparatus, and   wherein the second power feed unit is connected to the external power input terminal provided in the connection apparatus.   
     
     
         7 . The power supplying system according to  claim 1 ,
 wherein one of the electronic apparatus and the connection apparatus is provided with an external power input terminal capable of receiving the external power from an external power supply, and   wherein one of the first power feed unit and the second power feed unit is connected to the external power input terminal through the external power feed connection unit and the other power feed unit is connected to the external power input terminal, not through the external power feed connection unit.   
     
     
         8 . The power supplying system according to  claim 6 , further comprising:
 a reverse current prevention circuit that prevents a current from flowing from one external power supply to the other external power supply of the external power supply connected to the external power input terminal of the electronic apparatus and the external power supply connected to the external power input terminal of the connection apparatus.   
     
     
         9 . The power supplying system according to  claim 1 , further comprising:
 a power supply OR circuit that receives the output of the first power feed unit and the output of the second power feed unit, and supplies the power to the control unit.   
     
     
         10 . An electronic apparatus to which a connection apparatus is connectable, the electronic apparatus comprising:
 a first power feed unit that is capable of receiving internal power from a first battery in the electronic apparatus and of receiving external power, and preferentially outputs the external power rather than the internal power from the first battery;   a connection apparatus power input terminal connected to a second power feed unit that is provided in the connection apparatus, is capable of receiving internal power from a second battery in the connection apparatus and of receiving the external power, and preferentially outputs the external power rather than the internal power from the second battery;   an external power feed connection unit that connects a power feed path of the external power to the first power feed unit and a power feed path of the external power to the second power feed unit;   a selection unit that selects one of the first power feed unit and the second power feed unit as a supplying source of use power of the electronic apparatus; and   a control unit that causes the selection unit to select a power feed unit that receives the internal power between the first power feed unit and the second power feed unit.   
     
     
         11 . A power supplying method supplying power to an electronic apparatus using a first power feed unit that is provided in the electronic apparatus, is capable of receiving internal power from a first battery in the electronic apparatus and of receiving external power, and preferentially outputs the external power rather than the internal power from the first battery, and a second power feed unit that is provided in a connection apparatus connectable to the electronic apparatus, is capable of receiving internal power from a second battery in the connection apparatus and of receiving the external power, and preferentially outputs the external power rather than the internal power from the second battery, the method comprising:
 connecting a power feed path of the external power to the first power feed unit and a power feed path of the external power to the second power feed unit; and   selecting a power feed unit that receives the internal power between the first power feed unit and the second power feed unit as a supplying source of use power of the electronic apparatus.