Control system for charging batteries and electronic apparatus using same

Abstract

A control system for charging enabling efficient charging of rechargeable batteries in an electronic apparatus which charges its rechargeable batteries by using a charger circuit when driving the apparatus by using an external power source, including first detecting unit for detecting a differential value between a maximum permissible charging current allowed by the rechargeable batteries and a charging current flowing to the rechargeable batteries; second detecting unit for detecting a maximum usable current by detecting a differential value between a maximum supplyable current allowed by the external power source and the current consumption of the apparatus; third detecting unit for detecting a differential value between a maximum useable current and the charging current flowing to the rechargeable batteries; and control unit for controlling the system in accordance with the differential values detected by the first and third detecting units so that the charger circuit generates the maximum charging current within the range where the charging current flowing to the rechargeable batteries does not exceed either of the permissible charging current and the maximum useable current.

Description

50 55 is read to read the charging current flowing through the sense resistor R₀ and this is integrated to update the remaining amount of battery power of the rechargeable battery 50.

Next, at step 5, it is detected whether or not an instruction for stopping the apparatus has been issued. When it is detected that no command for stopping the apparatus has been issued, the processing routine goes to step 6, at which it is decided whether or not the remaining amount of battery power has reach full charge. When it is decided that it has not reached full charge the processing routine returns to step 4, at which the remaining amount of battery power continues to be updated. When it is decided that it has reached full charge, the processing routine goes to step 7, at which the control circuit 54 is stopped. At the subsequent step 8, the remaining amount of battery power is saved and the processing is ended.

Next at step 5, when it is detected that an instruction for stopping the apparatus has been issued, the processing routine immediately goes to step 7, at which the control circuit 54 is stopped. At the subsequent step 8, the remaining amount of battery power is saved and the processing is ended.

On the other hand, when it is detected at step 1 that the AC adapter has not been attached, that is, when the power of the rechargeable battery 50 is supplied to the DC/DC converter 52, the processing routine goes to step 9, at which the remaining amount of battery power of the rechargeable battery 50 which has been saved is read out. Subsequently, at step 10, the output voltage of the current measuring circuit 55 is read to read the discharging current flowing through the sense resistor R₀ and this is integrated, thereby to update the remaining amount of battery power of the rechargeable battery 50. Subsequently, at step 11, it is detected whether or not an instruction for stopping the apparatus has been issued. When it is detected that no instruction for stopping the apparatus has been issued, the processing routine returns to step 10, at which the remaining amount of battery power continues to be updated. When it is detected mat an instruction for stopping the apparatus has been issued, the processing routine goes to step 8, at which the remaining amount of battery power is saved and the processing is ended.

In this way, the microcontroller 56 stops the charging by accurately detecting the completion of charging of the rechargeable battery 50 even if the charging current which is generated by the charger circuit 53 dynamically changes.

The example of FIG. 4 adopted a configuration of inputting the maximum current supplyable by the AC adapter to the ACADP-terminal of the control circuit 54 in advance, but by utilizing the characteristic of the AC adapter, it is also possible to automatically detect the power supply capability of this AC adapter. According to this, it is possible to make the present invention further practical.

An example of the correspondence between the output current [A] and the output voltage [V] possessed by the AC adapter will be illustrated in FIG. 10. This shows that the AC adapter has a rated output voltage of 16.0V and a rated output current of 1500 mA.

As shown in this figure, the AC adapter maintains a voltage output of the rated output voltage when the output current is less man the rated output current, such as 0 to 1500 mA. If a current more than the rated output current is required, by lowering the output voltage to for example 15.0V, an overload state is notified to the load side. This has the function of cutting off the voltage output after the ultra-overload state is reached when a further larger current is required.

This means that, when the output voltage of the AC adapter is lowered to the prescribed lowest permissible output voltage, the limit of the power supply capability of the AC adapter is reached. By utilizing this characteristic, when the output voltage of the AC adapter is lowered to the lowest permissible output voltage, the charging current of the charger 53 is limited. This means that the maximum supply current of the AC adapter required to be originally input to the control circuit 54 can be omitted in the example of FIG. 4.

A fifth embodiment of the present invention using that method is illustrated in FIG. 11.

In the figure, the same elements as those explained referring to FIG. 4 are indicated by the same reference numerals.

The point of difference from the embodiment of FIG. 4 is that a configuration is adopted wherein the resistors R₁₁ and R₁₂ for monitoring the output voltage of the AC adapter which is connected to the DC connector 51 are provided in place of the sense resistor R₆ and the resistors R₇ to R₁₀ and the output voltage of the AC adapter divided by these resistors R₁₁ and R₁₂ is input to ERR2 minus terminal of the control circuit 54. Note that, the voltage e₁ corresponding to the maximum charging current allowable by the rechargeable battery 50 is input to the ERC1 terminal of the control circuit 54. Also, in the embodiment of FIG. 4, the maximum supply voltage allowable by the rechargeable battery 50 given from the outside is produced in an internal portion of the control circuit 54.

FIG. 12 illustrates an embodiment of the control circuit 54 used in the embodiment of FIG. 11.

As shown in this figure, the control circuit 54 used in the embodiment of FIG. 11 is constituted provided with four error amplifiers 544-i (i=1 to 4) in place of the six error amplifiers 540-i (i=1 to 6) provided in the control circuit 54 (shown in FIG. 5) used in be embodiment of FIG. 4.

This first error amplifier 544-1 (ERA₁) is an amplifier for measuring the voltage drop across the sense resistor R₀ and outputs a voltage proportional to the charging current charging current flowing through the sense resistor R₀. The third error amplifier 544-3 (ERA₃) amplifies a differential value between the charging current which is output by the first error amplifier 544-1 and the maximum charging current (e₁) allowed by (he rechargeable battery 50 to be given to the ERC1 terminal and inputs this amplified differential value to the PWM comparator 542.

The second error amplifier 544-2 (ERA₂) amplifies a differential value between the voltage supplied to the rechargeable battery 50 to be input to the first error amplifier 544-1 and the maximum supply voltage value allowable by the rechargeable battery 50 which is given by the internal battery and inputs this amplified differential value to the PWM comparator 542. The fourth error amplifier 544-4 (ERA₄) amplifies a differential value between the output voltage of the AC adapter which is detected by the resistors R₁₁ and R₁₂ and the lowest permissible output voltage of the AC adapter which is given by the internal battery (set to for example 15.0V) and inputs this amplified differential value to the PWM comparator 542.

Responding to the voltages which are output by the third error amplifier 544-3, second error amplifier 544-2, and the fourth error amplifier 544-4 and the triangular wave voltage which is output by the triangular wave generator 541, the PWM comparator 542 generates a pulse having a pulse width dependent on the input voltage. Receiving this pulse, the driver 543 turns the main transistor Tr₁ ON during the period when the PWM comparator 542 outputs the high level and, at the same time, turns the main transistor Tr₁ OFF during the period when the PWM comparator 542 outputs the low level.

This PWM comparator 542 is constituted by comparison circuits which are provided corresponding to the input voltages from three error amplifiers similar to that explained referring to FIG. 6 and which compare the output voltages of the error amplifiers and the triangular wave voltage which is generated by the triangular wave generator 541, output the high level when the input triangular wave voltage is smaller, and output the low level when the input triangular wave voltage is higher and an AND gate which calculates the AND value of the output values of all of the comparison circuits and outputs the result. Due to this, the comparison circuits generate pulses having pulse widths in accordance with the output voltages of the error amplifiers. The comparison circuit corresponding to (he error amplifier with a measured value exceeding the limit value operates so as not to generate a pulse since that error amplifier outputs a negative value or “0”.

Due to this configuration, as shown in FIG. 7A, the comparison circuits in the PWM comparator 542 produce long pulses of a higher level as me margin is larger when the input voltages from the error amplifiers are within the range of the limit value and do not generate pulses when the input voltages are not within that range. The AND gate inside the PWM comparator 542 outputs a pulse matching with the output from the comparator outputting the short pulse at the highest level as shown in FIG. 7B responding to the outputs of these comparators.

Namely, the PWM comparator 542 does not generate a pulse when one or more of the input voltages from the three error amplifiers exceeds the limit value and specifies the one nearest the limit value when there is none exceeding the limit value and generates a pulse of the high level having a length in accordance with this.

Responding to the generation of pulses of this PWM comparator 542, the driver 543 turns the main transistor Tr₁ ON during the period when the PWM comparator 542 outputs the high level and turns the main transistor Tr₁ OFF during the period when the PWM comparator 542 outputs the low level. Thus, the magnitude of the charging current which is generated by the charger 53 is controlled so that the output voltage of the error amplifier which originates the pulse of the PWM comparator 542 becomes the zero value.

Due to the control circuit 54 of this configuration, the charger 53 charges the rechargeable battery 50 by a charging current limited by whichever of the charging current which is detected by the sense resistor R₀ (with a limit value of the maximum charging current allowed by the rechargeable battery 50), the voltage supplied to the rechargeable battery 50 (with a limit value of the maximum supply voltage allowable by the rechargeable battery 50), and the output voltage of the AC adapter which is detected by the resistors R₁₁ and R₁₂ (with a limit value of the lowest permissible output voltage of the AC adapter) first reaches the limit value. That is, the charging current which is generated by the charger 53 is not limited up to the maximum output current allowed by the AC adapter.

In this way, the rechargeable battery 50 is charged by the maximum charging current within a range allowed by both of the rechargeable battery 50 and the AC adapter, and therefore it becomes possible to rapidly charge the rechargeable battery 50 at the time of the operation of the electronic apparatus 1.

Now, in the fifth embodiment of FIG. 11, it is assumed that the maximum charging current allowable by the rechargeable battery 50 is 1000 mA, the battery capacity of the rechargeable battery 50 is 1000 mAH, the maximum current supplyable by the AC adapter is 1500 mA, the maximum value of the current used when the apparatus operates is 1100 mA, an average value of the current used by the apparatus at the time of operation is 400 mA, and the current consumption when the apparatus is not being operated is 0 mA. Also, it is assumed that there is no limitation of the supply voltage in the rechargeable battery 50.

When the apparatus is stopped, all of the current which is supplied from the AC adapter can be used as the charging current of the rechargeable battery 50, and therefore the charging at the maximum current value 1000 mA allowable by the battery becomes possible. Accordingly, the charging at this time ends in about 1 hour.

On the other hand, when me apparatus is being operated, the current consumption dynamically changes in a range of from 0 to 1100 mA. Here, however, it is assumed that the current consumption of the apparatus is 1000 mA. The charger 53 operates so as to output 1000 mA since the maximum permissible charging current of the rechargeable battery 50 is 1000 mA. However, when the charging current which is generated by the charger 53 reaches 500 mA, the negative current value of the AC adapter becomes 1500 mA, and from a point of time when exceeding this 1500 mA, the output voltage of the AC adapter starts to drop. The control circuit 54 operates so as to limit the output of the charger 53 at the point of time when the output voltage starts to be lowered by monitoring the output voltage of this AC adapter, and consequently, the charging current which is generated by the charger 53 is restricted to the value of 500 mA.

When the current consumption of the apparatus is increased and becomes 1100 mA, a voltage drop of the AC adapter occurs along with the increase of this current consumption. Therefore the charger 53 further decreases the charging current to be generated according to the command of the control circuit 54 and decreases the same down to 400 mA. Subsequently, when the current consumption of me apparatus is decreased and becomes 800 mA, the output voltage of the AC adapter returns to the rated voltage. As a result, the limitation by the output voltage of the AC adapter is released and therefore the charger 53 increases the charging current to be generated according to the command of the control circuit 54 and meets the voltage drop point of the AC adapter at the point of tame when increasing the charging current to 700 mA. The current limitation starts there.

In this way, in the present invention, in accordance with the capacity of the AC adapter, the charging is carried out along with the dynamic change of the current consumption of the apparatus while dynamically changing the charging current in a range of from 1000 mA to 400 mA. The average current consumption of the apparatus is 400 mA, and therefore also this charging current becomes 1000 mA on the average. This charging current of 1000 mA is a current no different from that when the apparatus is stopped, and accordingly even if the apparatus is operating, the charging can be carried out in about 1 hour.

In this way, the present invention adopted a method wherein a function of measuring the current consumption on the apparatus side by monitoring the output voltage of the AC adapter is provided. In accordance with the current consumption on this apparatus side, the charging current of the charger 53 is dynamically changed, thereby to enable constant charging by the maximum capability of the AC adapter. Due to this, the charging time of the rechargeable battery 50 can be greatly shortened.

Contrary to this, the related art does not adopt a structure for dynamically detecting the dynamically changing power consumption on the apparatus side and therefore is designed considering the maximum power consumption. Due to this, when the maximum power consumption at the time of the operation of apparatus is 1100 mA and the maximum current supplyable by the AC adapter is 1500 mA, the current useable by the charger 53 becomes 400 mA. As a result, irrespective of any current consumption of the apparatus, at the time of the operation of the apparatus, the charging is always carried out at 400 mA, and a charging time of about 3 hours becomes necessary.

In this way, in the present invention, by performing the charging in accordance with the capability of the AC adapter, it becomes possible to greatly shorten the charging time of the rechargeable battery 50.

The present invention was explained according to the illustrated embodiments, but the present invention is not restricted to this. For example, in the concrete examples, the present invention was described by using a rechargeable battery 50 in which the supply voltage is restricted, but it is also possible to use a rechargeable battery 50 in which the supply voltage is not restricted. In this case, it is not necessary to constitute the system so as to limit the charging current by this supply voltage.

As explained above, according to the present invention, where an electronic apparatus is provided with a rechargeable battery, it becomes possible to charge the rechargeable battery by the maximum charging current within a range allowed by both of the rechargeable batteries and the external power source, and therefore it becomes possible to rapidly charge the rechargeable battery at the time of operation of the electronic apparatus.

Further, according to the present invention, even if the charging current of the rechargeable batteries dynamically changes, it becomes possible to accurately detect the completion of charging of the rechargeable batteries. Further, according to the present invention, by using the same resistor for the sense resistor for the detection of the charging current of the rechargeable batteries and the sense resistor for the detection of the discharging current of the rechargeable batteries, it becomes possible to measure the charging/discharging current of the rechargeable batteries with a simple structure.

Claims

1. A system for controlling the supply of power from an external power source to rechargeable batteries in an apparatus which can be powered either by the external power source or the rechargeable batteries, comprising:

a first detector for detecting a difference between a maximum permissible charging current allowed by the rechargeable batteries and a charging current flowing to the rechargeable batteries;

a second detector for detecting a maximum useable current by detecting a difference between a maximum suppliable current allowed by the external power source and the current being consumed by the apparatus;

a third detector for detecting a difference between the maximum useable current and the charging current flowing to the rechargeable batteries; and

a controller for controlling power supplied from the external power source to the rechargeable batteries in accordance with the differences detected by the first and third detectors so that the charging current flowing to the rechargeable batteries does not exceed the maximum permissible charging current and does not exceed the maximum useable current.

2. A system for controlling as set forth in claim 1, further comprising a fourth detector for detecting a difference between a maximum permissible supply voltage allowed by said rechargeable batteries and a voltage applied to said rechargeable batteries, said control means controlling the power supplied from the external power source to the rechargeable batteries in accordance wins the difference detected by the fourth detector so mat the voltage applied to the rechargeable batteries does not exceed the maximum permissible supply voltage.

3. A system for controlling the supply of power from an external power source to rechargeable batteries in an apparatus which can be powered by either the external power source or the rechargeable batteries, comprising:

a first detector for detecting a difference between a maximum permissible charging current allowed by the rechargeable batteries and a charging current flowing to the rechargeable batteries;

a second detector for detecting a difference between a lowest permissible output voltage allowed by the external power source and an output voltage which is being output by the external power source; and

a controller for controlling power supplied from the external power source to the rechargeable batteries in accordance with the differences detected by the first and second detectors so that the charging current flowing to the rechargeable batteries does not exceed the maximum permissible charging current and the output voltage being output by the external power source is not less than the lowest permissible output voltage.

4. A control system for controlling as set forth in claim 3, further comprising a third detector for detecting a difference between the maximum permissible supply voltage allowed by the rechargeable batteries and a voltage applied to said rechargeable batteries, said control means controlling the power supplied from the external power source to the rechargeable batteries in accordance with the difference detected by the third detector so that the voltage applied to the rechargeable batteries does not exceed the maximum permissible supply voltage.

5. A system for controlling as set forth in claim 1,

wherein said controller controls the power supplied from the external power source to the rechargeable batteries by determining if either the first or third detector detects a negative difference thus indicating mat the charging current exceeds a maximum,

wherein if either of the first or third detector detects a negative difference, the controller selects the largest negative difference and controls the charging current to increase the largest negative difference to a zero difference, and

wherein if neither of the first or third detector detects a negative difference, the controller selects the largest positive difference and controls the charging current to decrease the largest positive difference to a zero difference.

6. A system for controlling as set form in claim 2,

wherein said controller controls the power supplied from the external power source to the rechargeable batteries by determining if any of the first third or fourth detector detects a negative difference thus indicating that the charging current or the supply voltage exceeds a maximum,

wherein if any of the first third or fourth detector detects a negative difference, the controller selects the largest negative difference and controls the charging current to increase the largest negative difference to a zero difference, and

wherein if none of the first third or fourth detector detects a negative difference, the controller selects the largest positive difference and controls the charging current to decrease the largest positive difference to a zero difference.

7. A system for controlling as set forth in claim 3,

wherein said controller controls the power supplied from the external power source to the rechargeable batteries by determining if either of the detector detects a negative difference thus indicating that the charging current exceeds a minimum or the output voltage is less then a minimum,

wherein if either of the detector detects a negative difference, the controller selects the largest negative difference and controls the charging current to increase the largest negative difference to a zero difference, and

wherein if neither of the detector detects a negative difference, the controller selects the largest positive difference and controls the charging current to decrease the largest positive difference to a zero difference.

8. A system for controlling as set forth in claim 4,

wherein said controller controls the power supplied from the external power source to the rechargeable batteries by determining if any of the detector detects a negative difference thus indicating that a current or a voltage is greater than a maximum or less than a minimum,

wherein if any of the detector detects a negative difference, the controller selects the largest negative difference and controls the charging current to increase the largest negative difference to a zero difference, and

wherein if none of the detector detects a negative difference, the controller selects the largest positive difference and controls the charging current to decrease the largest positive difference to a zero difference.

9. A system for controlling the supply of power from a charger circuit to rechargeable batteries, the rechargeable batteries being used to supply power to a power supply circuit, comprising:

a sense resistor having two ends, located between the rechargeable batteries and a connection point for the charger circuit and the power supply circuit, the sense resistor detecting current flowing into and out of the rechargeable batteries;

a current measurement device having two inputs connected respectively to the two ends of the sense resistor, the current measurement device determining which of the two inputs has a larger voltage and generating a voltage in accordance with the difference between the voltages of the two inputs to thereby measure the current flowing into or out of the rechargeable battery; and

a control circuit regulating to a constant current the current flowing into the rechargeable batteries, based on the current flowing into the rechargeable batteries detected by the sense resistor.

10. A system for controlling as set forth in claim 9, wherein the control circuit has two inputs connected respectively to the two ends of the sense resistor.

11. An electronic apparatus having an input section for inputting power from a power source and capable of charging a battery by using the power from the input section while the electronic apparatus makes a load operate by applying the power input from the input section to the load, an output voltage of the power source being substantially a constant voltage, the output voltage of the power source falling to less than said constant voltage when the power source outputs more than a predetermined current value, the power applied to the load from the input section varying based on the state of the load, the electronic apparatus comprising:

a power input sensor for obtaining power-input information by sensing an input of the power from the input section;

a charger for charging the battery by using the power from the input section; a charge control circuit for controlling the charging power the charger supplies to the battery based on the power input information obtained by the power input sensor so that a sum of the power applied to the load and the power charged to the battery from the input section is substantially in a current range in which said output voltage of the power source is substantially the constant voltage; and

a charging voltage detector for detecting a charging voltage of the battery, wherein the charge control circuit controls the charging voltage so that the charging voltage detected by the charging voltage detector becomes a value assigned to the battery or lower.

12. An electronic apparatus as set forth in claim 11, further comprising:

a charging current detector for detecting a charging current of the battery, wherein the charge control circuit controls the charging current based on the detected charging current so that the charging current becomes a value assigned to the battery or lower.

13. An electronic apparatus as set forth in claim 11, wherein the power source is able to supply a maximum permissible supply current of the power source in the current range.

14. A charging apparatus for an electronic apparatus that has an input section for inputting power from a power source and is capable of charging a battery by using the power from the input section while the electronic apparatus makes a load operate by applying the power input from the input section to the load, an output voltage of the power source being substantially a constant voltage, the output voltage of the power source falling to less than said constant voltage when the power source outputs more than a predetermined current value, the power applied to the load from the input section varying based on the state of the load, the charging apparatus comprising:

a charger for charging the battery by using the power from the input section;

a charge control circuit for controlling the charging power the charger supplies to the battery, based on the power input information obtained by power input sensor for obtaining the power input information by sensing an input of the power from the input section, so that a sum of the power applied to the load and the power charged to the battery from the input section is substantially in a current range in which said output voltage of the power source is substantially the constant voltage, wherein

the charge control circuit controls the charging current, based on a charging current detected by a charging current detector for detecting the charging current of the battery, so that the charging current becomes a value assigned to the battery or lower.

15. A charging apparatus as set forth in claim 14, wherein the charge control circuit further controls the charging voltage so that a voltage detected by a charging voltage detector for detecting the charging voltage of the battery becomes a value assigned to the battery or lower.

16. A charging apparatus as set forth in claim 14, wherein the power source is able to supply a maximum permissible supply current of the power source in the current range.

17. A charge control circuit for an electronic apparatus that has an input section for inputting power from a power source and a charger for charging a battery by using the power from the input section while the electronic apparatus making a load operate by applying the power input from the input section to the load, an output voltage of the power source being substantially a constant voltage, the output voltage of the power source falling to less than said constant voltage when the power source outputs more than a predetermined current value, the power applied to the load from the input section varying based on the state of the load, the charge control circuit comprising:

a control circuit for controlling the charging power the charger supplies to the battery, based on power input information obtained by a power input sensor for obtaining the power input information by sensing an input of the power from the input section, so that a sum of the power applied to the load and the power charged to the battery from the input section is substantially in a current range in which said output voltage of the power source is substantially the constant voltage, wherein

the control circuit controls the charging voltage so that a voltage detected by a charging voltage detector for detecting the charging voltage of the battery becomes a value assigned to the battery or lower.

18. A charge control circuit as set forth in claim 17, wherein the control circuit controls the charging current based a charging current detected by a charging current detector for detecting the charging current of the battery so that the charging current becomes a value assigned to the battery or lower.

19. A charge control circuit as set forth in claim 17, wherein the power source is able to supply a maximum permissible supply current of the power source in the current range.

20. An electronic apparatus having a charger for outputting a charging current to charge a battery by using power of a power source and supplying the power from the battery to a load to make the load operate, the electronic apparatus comprising:

a sense resistor provided between a connection point between the power source and the charger and the battery, for detecting a charging current flowing into the battery and for detecting a current flowing out from the battery; and

a controller for controlling the charging current from the charger based on a current value measured by using the sense resistor.

21. An electronic apparatus as set forth in claim 20, further comprising:

a current measuring section for discriminating which one of two input potentials applied to both ends of the sense resistor is larger, and for detecting both a charging current and a discharging current from a voltage generated according to a difference between the two input potentials.

22. An electronic apparatus as set forth in claim 20, further comprising:

a remaining-amount determining section for determining a remaining amount of current charged to the battery based on a charging current value measured by the sense resistor.

23. An electronic apparatus as set forth in claim 20, further comprising:

a remaining-amount determining section for determining a remaining amount of current charged to the battery based on a discharging current value measured by the sense resistor.

24. An electronic apparatus having a charger for supplying a charging current to a battery by using power of a power source to make a load operate based on the power supplied from the battery, the electronic apparatus comprising:

a sense resistor disposed between the battery and a connection point between the power source and the charger, for detecting a charging current flowing into the battery in order to control the charging current of the charger; and

a detector for detecting a discharging current by the sense resistor when the power from the battery is supplied to the load.

25. An electronic apparatus having an input section for inputting power from a power source and capable of charging a battery by using the power from the input section while making a load operate by applying the power input from the input section to the load, a current applied to the load from the input section varying based on the state of the load, the electronic apparatus comprising:

a power input sensor which obtains power-input information by sensing an input of the power from the input section;

a charger which charges the battery by using a current from the input section; a charge control circuit which controls the charger to change a current charged to the battery by determining whether an input current from the power source reaches a predetermined value or not in accordance with the power-input information sensed by the power input sensor, so that a sum of the current applied to the load and the current charged to the battery from the input section does not exceed the predetermined value; and

a charging voltage detector which detects a charging voltage of the battery, wherein the charge control circuit controls the charging voltage so that the charging voltage detected by the charging voltage detector becomes a value assigned to the battery or lower.

26. An electronic apparatus as set forth in claim 25, further comprising:

a charging current detector which detects a charging current of the battery, wherein the charge control circuit controls the charging current based on the detected charging current so that the charging current becomes a value assigned to the battery or lower.

27. An electronic apparatus as set forth in claim 25, wherein the predetermined value is a maximum permissible supply current of the power source.

28. A charging apparatus for an electronic apparatus that has an input section for inputting power from a power source and is capable of charging a battery by using the power from the input section while the electronic apparatus making a load operate by applying the power input from the input section to the load, a current applied to the load from the input section varying based on the state of the load, the charging apparatus comprising:

a charger which charges the battery by using the power from the input section;

a charge control circuit which controls the charger to change a current charged to the battery by determining whether an input current from the power source reaches a predetermined value or not in accordance with the power-input information sensed by a power input sensor which obtains the power input information by sensing an input of power from the input section, so that a sum of the current applied to the load and the current charged to the battery from the input section does not exceed the predetermined value, wherein

the charge control circuit further controls the charging voltage so that a voltage detected by a charging voltage detector for detecting the charging voltage of the battery becomes a value assigned to the battery or lower.

29. A charging apparatus as set forth in claim 28, wherein the charge control circuit controls the charging current, based on a charging current detected by a charging current detector for detecting the charging current of the battery, so that the charging current becomes a value assigned to the battery or lower.

30. A charging apparatus as set forth in claim 28, wherein the predetermined value is a maximum permissible supply power of the power source.

31. A charge control circuit for an electronic apparatus that has an input section for inputting power from a power source and a charger for charging a battery by using the power from the input section and while the electronic apparatus making a load operate by applying the power input from the input section to the load, a current applied to the load from the input section varying based on the state of the load, the charge control circuit comprising:

a charge control circuit which controls the charger to change a current charged to the battery by determining whether an input current from the power source reaches a predetermined value or not in accordance with the power-input information sensed by a power input sensor which obtains the power input information by sensing an input of power from the input section, so that a sum of the current applied to the load and the current charged to the battery from the input section does not exceed the predetermined value, wherein

the control circuit controls the charging voltage so that a voltage detected by a charging voltage detector for detecting the charging voltage of the battery becomes a value assigned to the battery or lower.

32. A charge control circuit as set forth in claim 31, wherein the control circuit controls the charging current based a charging current detected by a charging current detector for detecting the charging current of the battery so that the charging current becomes a value assigned to the battery or lower.

33. A charge control circuit as set forth in claim 31, wherein the predetermined value is a maximum permissible supply power of the power source.

34. An electronic apparatus connected to an AC adapter which supplies DC power, capable of charging a battery by using power from the AC adapter while making a load operate by using the DC power supplied from the AC adapter, the power given to the load varying based on the state of the load, the electronic apparatus comprising:

a connector which receives the DC power from the AC adapter;

a charger, connected to the battery, which supplies charging power to the battery by using the power from the connector; and

a charge control circuit which controls the charger to control the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery becomes a value assigned in advance.

35. An electronic apparatus as set forth in claim 34, further comprising a charging current detector which detects a charging current supplied to the battery, wherein the charge control circuit controls the charging current so that the charging current becomes equal to or lower than a value assigned to the battery, based on a value of the charging current to the battery detected by the charging current detector.

36. An electronic apparatus as set forth in claim 34, further comprising a charging voltage detector which detects a charging voltage supplied to the battery, wherein the control circuit controls the charging voltage so that the charging voltage becomes equal to or lower than a value assigned to the battery, based on a value of the charging voltage to the battery detected by the charging voltage detector.

37. An electronic apparatus as set forth in claim 34, wherein the value assigned in advance is a maximum permissible supply power of the AC adapter.

38. An electronic apparatus as set forth in claim 34, wherein the charge control circuit controls the charging power the charger supplies to the battery, based on sensed information on the power input from the connector, so that a sum of the power applied to the load and the power charged to the battery becomes the value assigned in advance.

39. A charging apparatus for charging a battery for an electronic apparatus that is connected to an AC adapter and that is capable of charging the battery by using power from the AC adapter while the electronic apparatus making a load operate by using DC power supplied from the AC adapter, the power given to the load varying based on the state of the load, the charging apparatus comprising:

a charger, connected to the battery, which supplies charging power to the battery by using the power from a connector that is connected to the AC adapter to receive the DC power from the AC adapter; and

a charge control circuit which controls the charger to control the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery becomes a value assigned in advance.

40. A charging apparatus as set forth in claim 39, wherein the charge control circuit controls the charging current so that a charging current becomes equal to or lower than the value assigned to the battery, based on a detected value of the charging current to the battery.

41. A charging apparatus as set forth in claim 39, wherein the charge control circuit controls a charging voltage so that the charging voltage becomes equal to or lower than a value assigned to the battery, based on a detected value of the charging voltage to the battery.

42. A charging apparatus as set forth in claim 39, wherein the value assigned in advance is a maximum permissible supply power of the AC adapter.

43. A charging apparatus as set forth in claim 39, wherein the charge control circuit controls the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery becomes the value assigned in advance, based on sensed information on the power input from the connector.

44. A charge control circuit for controlling a charger in an electronic apparatus having a connector connected to an AC adapter to receive DC power from the AC adapter, the charger being connected to a battery and supplying charging power to the battery by using the power from the connector, the electronic apparatus making a load operate by using the DC power supplied from the AC adapter, the power given to the load varying based on the state of the load, the charge control circuit comprising:

a control circuit which controls the charger to control the charging power the charge supplies to the battery so that a sum of the power applied to the load and the power charged to the battery becomes a value assigned in advance.

45. A charge control circuit as set forth in claim 44, wherein the control circuit controls a charging current based on a detected value of the charging current to the battery so that the charging current becomes equal to or lower than a value assigned to the battery.

46. A charge control circuit as set forth in claim 44, wherein the control circuit controls a charging voltage based on a detected value of the charging voltage to the battery so that the charging voltage becomes equal to or lower than a value assigned to the battery.

47. A charge control circuit as set forth in claim 44, wherein the value assigned in advance is a maximum permissible supply power of the AC adapter.

48. A charge control circuit as set forth in claim 44, wherein the control circuit controls the charging power the charger supplies to the battery, based on sensed information on the power input from the connector, so that a sum of the power applied to the load and the power charged to the battery becomes the value assigned in advance.

49. An electronic apparatus capable of charging a battery by using power from a power source while making a load operate by using the power supplied from the power source, the electronic apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source;

a detector which detects the power applied to the load;

a charging current detector detects a charging current to the battery; and

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load that has been detected becomes a value assigned in advance, and which controls the charging current based on the detected charging current so that the charging current to the battery becomes equal to or lower than a charging current value assigned in advance to the battery.

50. An electronic apparatus capable of charging a battery by using power from a power source while making a load operate by using the power supplied from the power source, the electronic apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source;

a detector which detects the power applied to the load;

a charging voltage detector which detects a charging voltage to the battery; and

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load that has been detected becomes a value assigned in advance, and which controls the charging voltage based on the detected charging voltage so that the charging voltage becomes within a voltage value assigned in advance to the battery.

51. An electronic apparatus capable of charging a battery by using power from a power source having a prescribed maximum permissible supply power while making a load operate by using the power supplied from the power source, the electronic apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source;

a detector which detects the power applied to the load; and

a control circuit which controls the charger to adjust the charger to supply the charging power so that the charging power is the prescribed maximum permissible supply power minus the detected power applied to the load.

52. A charging apparatus for an electronic apparatus capable of charging a battery by using power from a power source while the electronic apparatus makes a load operate by using the power supplied from the power source, the charging apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source; and

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load detected by a detector which detects the power applied to the load becomes a value assigned in advance, and which controls the charging current, based on a charging current value detected by a charging current detector which detects the charging current to the battery, so that the charging current to the battery becomes equal to or lower than a charging current value assigned in advance to the battery.

53. A charging apparatus for an electronic apparatus capable of charging a battery by using power from a power source while the electronic apparatus making a load operate by using the power supplied from the power source, the charging apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source; and

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load detected by a detector which detects the power applied to the load becomes a value assigned in advance, and which controls the charging voltage, based on a charging voltage detected by a charging voltage detector which detects the charging voltage of the battery, so that the charging voltage becomes within a voltage value assigned in advance to the battery.

54. A charging apparatus for an electronic apparatus capable of charging a battery by using power from a power source having a prescribed maximum permissible supply power while the electronic apparatus makes a load operate by using the power supplied from the power source, the charging apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source; and

a control circuit which controls the charger so that the charger supplies the charging power so that the charging power is the maximum permissible supply power minus the power applied to the load that has been detected by a detector which detects the power applied to the load.

55. A charge control circuit for controlling a charger for an electronic apparatus that makes a load operate by using power supplied from a power source and that has the charger for supplying charging power to a battery by using the power from the power source, the charge control circuit comprising:

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load detected by a detector which detects the power applied to the load becomes a value assigned in advance, and which controls a charging current, based on a charging current detected by a charging current detector which detects the charging current to the battery, so that the charging current supplied to the battery becomes equal to or lower than a charging current value assigned in advance to the battery.

56. A charge control circuit for controlling a charger for an electronic apparatus that makes a load operate by using power supplied from a power source and that has the charger for supplying charging power to a battery by using the power from the power source, the charge control circuit comprising:

a control circuit which controls the charger to generate the charging power so that a sum of the charging power supplied to the battery and the power applied to the load detected by a detector which detects the power applied to the load becomes a value assigned in advance, and which controls the charging voltage, based on a charging voltage detected by a charging voltage detector which detects the charging voltage to the battery, so that the charging voltage becomes within a voltage value assigned in advance to the battery.

57. A charge control circuit for controlling a charger for an electronic apparatus that makes a load operate by using power supplied from a power source having a prescribed maximum permissible supply power and that has the charger for supplying charging power to a battery by using the power from the power source, the charge control circuit comprising:

a control circuit which controls the charger so that the charger supplies the charging power which is the prescribed maximum permissible supply power minus the power applied to the load detected by a detector which detects the power applied to the load.

58. An electronic apparatus capable of charging a battery by using power from a power source while making a load operate by using the power supplied from the power source, the power applied to the load from the power source varying based on the state of the load, the electronic apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source;

a charging current detector which detects a charging current of the battery; a charge control circuit which controls the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery from the power source becomes a value assigned in advance, and which controls the charging current based on the charging current detected by the charging current detector so that the charging current becomes a limit value assigned to the battery or a lower value; and

a charging voltage detector which detects a charging voltage of the battery, wherein the charge control circuit further controls the charging voltage so that the voltage detected by the charging voltage detector becomes a value assigned to the battery or lower.

59. An electronic apparatus as set forth in claim 58, wherein the pre-assigned value is a maximum permissible supply power of the power source.

60. An electronic apparatus as set forth in claim 58, wherein the charge control circuit controls the charging power the charger supplies to the battery, based on sensed information on the input from the power source, so that a sum of the power applied to the load and the power charged to the battery from the power source becomes the pre-assigned value.

61. A charging apparatus for an electronic apparatus that is capable of charging a battery by using power supplied from a power source while the electronic apparatus making a load operate by using the power from the power source, the power applied to the load from the power source varying based on the state of the load, the charging apparatus comprising:

a charger which supplies charging power to the battery by using the power from the power source; and

a charge control circuit which controls the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery from the power source becomes a value assigned in advance, and which controls the charging current, based on a charging current detected by a charging current detector which detects the charging current to the battery, so that the charging current becomes a value assigned to the battery or a lower value, wherein

the charge control circuit further controls the charging voltage so that a charging voltage detected by a charging voltage detector which detects the voltage charged to the battery becomes a value assigned to the battery or lower.

62. A charging apparatus as set forth in claim 61, wherein the preassigned value is a maximum permissible supply power of the power source.

63. A charging apparatus as set forth in claim 61, wherein the charge control circuit controls the charging power the charger supplies to the battery, based on sensed information on the input from the power source, so that a sum of the power applied to the load and the power charged to the battery becomes the pre-assigned value.

64. A charge control circuit for an electronic apparatus that makes a load operate by using power supplied from a power source and that has a charger for supplying charging power to a battery by using the power from the power source, the power applied to the load from the power source varying based on the state of the load, the charge control circuit comprising:

a control circuit which controls the charging power the charger supplies to the battery so that a sum of the power applied to the load and the power charged to the battery from the power source becomes a value assigned in advance, and which controls the charging current based on a charging current detected by a charging current detector which detects the charging current to the battery so that the charging current becomes a value assigned to the battery or a lower value.

65. A charge control circuit as set forth in claim 64, wherein the control circuit further controls the charging voltage so that a charging voltage detected by a charging voltage detector which detects the voltage charged to the battery becomes a value assigned to the battery or lower.

66. A charge control circuit as set forth in claim 64, wherein the preassigned value is a maximum permissible supply power of the power source.

67. A charge control circuit as set forth in claim 64, wherein the control circuit controls the charging power the charger supplies to the battery, based on sensed information on the input from the power source, so that a sum of the power applied to the load and the power from the power source charged from the power source to the battery becomes the pre-assigned value.

68. A charge control circuit for an electronic apparatus that has an input section for inputting power from a power source and a charger for charging a battery by using the power from the input section while the electronic apparatus makes a load operate by applying the power input from the input section to the load, an output voltage of the power source being substantially a constant voltage, the output voltage of the power source falling to less than said substantially constant voltage when the power source outputs more than a predetermined current value, the power applied to the load from the input section varying based on the state of the load, the charge control circuit comprising:

a control circuit which controls the charging power the charger supplies to the battery, based on power input information obtained by a power input sensor which obtains the power input information by sensing an input of the power from the input section, so that a sum of the power applied to the load and the power charged to the battery from the input section is substantially in a current range in which said output voltage of the power source is the substantially constant voltage, wherein the control circuit controls a charging voltage the charger supplies to the battery so that the charging voltage detected by a charging voltage detector becomes a value assigned to the battery or lower, wherein

the control circuit controls the charging power the charger supplies to the battery, based on sensed information on the input from the power source, so that a sum of the power applied to the load and the power from the power source charged from the power source to the battery becomes the pre-assigned value.

69. An electronic apparatus connected to an AC adapter which supplies DC current, capable of charging a battery by using current from the AC adapter while making a load operate by using the DC current supplied from the AC adapter, the current given to the load varying based on the state of the load, the electronic apparatus comprising:

a connector connected to the AC adapter, which receives DC current from the AC adapter;

a charger, connected to the battery, which supplies charging current to the battery by using the current from the connector;

a charger control circuit which controls the charger to control the charging current the charger supplies to the battery so that a sum of the current applied to the load and the current charged to the battery becomes a value assigned in advance; and a charging voltage detector which detects a charging voltage supplied to the battery, wherein

the control circuit controls the charging voltage so that the charging voltage becomes equal to or lower than a value assigned to the battery, based on a value of the charging voltage to the battery detected by the charging voltage detector.

70. An electronic apparatus as set forth in claim 69, further comprising a charging current detector which detects a charging current supplied to the battery, wherein the charge control circuit controls the charging current so that the charging current becomes equal to or lower than a value assigned to the battery, based on a value of the charging current to the battery detected by the charging current detector.

71. An electronic apparatus as set forth in claim 69, wherein the value assigned in advance is a maximum permissible supply current of the AC adapter.

72. An electronic apparatus as set forth in claim 69, wherein the charge control circuit controls the charging current the charger supplies to the battery, based on sensed information on the power input from the connector, so that a sum of the current applied to the load and the current charged to the battery becomes the value assigned in advance.

73. A charging apparatus for charging a battery for an electronic apparatus that is connected to an AC adapter and that is capable of charging the battery by using current from the AC adapter while the electronic apparatus making a load operate by using DC current supplied from the AC adapter, the current given to the load varying based on the state of the load, the charging apparatus comprising:

a charger, connected to the battery, which supplies charging current to the battery by using the current from a connector that is connected to the AC adapter to receive the DC current from the AC adapter; and

a charger control circuit which controls the charger to control the charging power the charger supplies to the battery so that a sum of the current applied to the load and the current charged to the battery becomes a value assigned in advance, wherein

the charge control circuit controls a charging voltage so that the charging voltage becomes equal to or lower than a value assigned to the battery, based on a detected value of the charging voltage to the battery.

74. A charging apparatus as set forth in claim 73, wherein the charge control circuit controls the charging current so that a charging current becomes equal to or lower than the value assigned to the battery, based on a detected value of the charging current to the battery.

75. A charging apparatus as set forth in claim 73, wherein the value assigned in advance is a maximum permissible supply current of the AC adapter.

76. A charging apparatus as set forth in claim 73, wherein the charge control circuit controls the charging current the charger supplies to the battery so that a sum of the current applied to the load and the current charged to the battery becomes the value assigned in advance, based on sensed information on input from the connector.

77. A charge control circuit for controlling a charger in an electronic apparatus having a connector connected to an AC adapter to receive DC current from the AC adapter, the charger being connected to a battery and supplying charging current to the battery by using the current from the connector, the electronic apparatus making a load operate by using the DC current supplied from the AC adapter, the current given to the load varying based on the state of the load, the charge control circuit comprising:

a control circuit which controls the charger to control the charging current the charger supplies to the battery so that a sum of the current applied to the load and the current charged to the battery becomes a value assigned in advance, wherein

the control circuit controls a charging voltage based on a detected value of the charging voltage to the battery so that the charging voltage becomes equal to or lower than a value assigned to the battery.

78. A charge control circuit as set forth in claim 77, wherein the control circuit controls a charging current based on a detected value of the charging current to the battery so that the charging current becomes equal to or lower than a value assigned to the battery.

79. A charge control circuit as set forth in claim 77, wherein the value assigned in advance is a maximum permissible supply current of the AC adapter.

80. A charge control circuit as set forth in claim 77, wherein the control circuit controls the charging current the charger supplies to the battery, based on sensed information on input from the connector, so that a sum of the current applied to the load and the current charged to the battery becomes the value assigned in advance.