Power circuit, power supply method, and electronic device

• US 20020036479A1
• Filed: 09/18/2001
• Published: 03/28/2002
• Est. Priority Date: 09/22/2000
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Aoyagi, Koji, Onozuka, Kuniharu
• Granted Patent: US 6,603,285 B2
• Time in Patent Office: Days
• US Class Current: 320/103
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection

Abstract

A power circuit is provided so that a charge can be normally driven even during replacement of a first battery. This power circuit comprises: first and second batteries for driving a charge; a first battery voltage detection means; a first switch for controlling a second battery power supply path based on an output of the voltage detection means; an overcharge prevention means for preventing an overcharge for the secondary battery caused by the first battery; and a switch controlled by an output of the overcharge prevention means.

Claims

1. A power circuit comprising:

a first battery for driving a charge;

a second battery for driving the charge in place of the first battery;

a voltage detection means for detecting a terminal voltage of the first battery;

a first switch for controlling a power supply path of the second battery based on an output of the voltage detection means;

an overcharge prevention means for preventing an overcharge for the second battery caused by the first battery; and

a second switch connected to a charge path for the second battery and controlled by the output of the overcharge prevention means, said power circuit characterized in that, when the first battery is lowered to a predetermined voltage or less, the charge is driven by means of the second battery.

2. A power circuit as claimed in claim 1, characterized in that the voltage detection means comprises:

a voltage divider circuit for dividing a voltage of the first battery;

and a voltage comparator in which a voltage dividing output of the voltage divider circuit and a reference voltage obtained by the charge side are supplied.

3. A power circuit as claimed in claim 2, characterized in that a display element prompting battery replacement is connected to an output stage of the voltage comparator, and, when the voltage of the first battery is lowered to the predetermined voltage or less, the display element is lit.

4. A power circuit as claimed in claim 1, characterized in that an overcharge prevention means comprises:

a voltage divider circuit for dividing a drive voltage supplied from the charge side;

and a voltage comparator for comparing a terminal voltage of the second battery.

5. A power circuit as claimed in claim 1, characterized in that a voltage increase DC-DC converter is connected onto a power supply path of the second battery.

6. A power circuit as claimed in claim 2, characterized in that the overcharge prevention means comprises:

a voltage divider circuit for dividing a drive voltage supplied from the charge side;

and a voltage comparator for comparing a terminal voltage of the second battery when a voltage dividing output of the voltage divider circuit is defined as a reference voltage.

7. A power circuit as claimed in claim 6, characterized in that a pressure increase DC-DC converter is connected onto a power supply path of the second battery.

8. A power circuit as claimed in claim 7, characterized in that a display element prompting battery replacement is connected to an output stage of the voltage comparator, and, when a voltage of the first battery is lowered to a predetermined voltage or less, the display element is lit.

9. A power supply method comprising:

a voltage detection step of detecting a terminal voltage of a first battery for driving a charge;

a step of controlling a first switch connected to a power supply path of a second battery for driving the charge in place of the first battery based on the result of the voltage detection step;

an overcharge prevention step of preventing an overcharge for the second battery caused by the first battery; and

a step of controlling a second switch for preventing an overcharge connected to a charge path for the second battery based on the result of the overcharge preventing step, said power supply method characterized in that, when the first battery is lowered to a predetermined voltage or less, the charge is driven by the second battery.

10. A power supply method as claimed in claim 9, characterized in that the voltage detection step compares a voltage dividing output having divided thereby a voltage of the first battery with a reference voltage obtained by the charge side.

11. A power supply method as claimed in claim 10, characterized in that, when a voltage of the first battery is lowered to a predetermined voltage or less, a display element is lit.

12. A power supply method as claimed in claim 9, characterized in that the overcharge prevention step defines a voltage dividing output having divided thereby a drive voltage supplied from the charge side, and compares the reference voltage with a terminal voltage of the second battery.

13. A power supply method as claimed in claim 9, characterized by further comprising the step of increasing a terminal voltage of the second battery.

14. A power supply method as claimed in claim 10, characterized in that the overcharge prevention step defines a voltage dividing output having divided thereby a drive voltage supplied from the charge side, and compares the reference voltage with a terminal voltage of the second battery.

15. A power supply method as claimed in claim 14, characterized by further comprising the step of increasing a terminal voltage of the second battery.

16. A power supply method as claimed in claim 15, characterized in that, when a voltage of the first battery is lowered to a predetermined voltage or less, a display element is lit.

18. An electronic device as claimed in claim 17, characterized in that the electronic device is a hand held electronic device.

19. An electronic device as claimed in claim 18, characterized in that the electronic device is a hand held telephone set.

20. An electronic device as claimed in claim 18, characterized in that the hand held electronic device is a hand held personal computer.

21. An electronic device as claimed in claim 18, characterized in that the hand held electronic device is a hand held digital camera.

22. An electronic device as claimed in claim 18, characterized in that the hand held electronic device is a hand held game device.

17. An electronic device comprising:

a first battery for driving a charge;

a second battery for driving the charge in place of the first battery;

a voltage detection means for detecting a terminal voltage of the first battery;

a first switch for controlling a power supply path of the second battery based on an output of the voltage detection means;

an overcharge prevention means for preventing an overcharge for the second battery caused by the first battery; and

a second switch connected to a charge path for the second battery and controlled by the output of the overcharge prevention means, said power circuit characterized in that, when the first battery is lowered to a predetermined voltage or less, the charge is driven by means of the second battery.