Battery-powered electronic equipment with charge control circuit

• US 7,336,053 B2
• Filed: 03/30/2004
• Issued: 02/26/2008
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: Ablic Inc. (Minebea Mitsumi, Inc.)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Furuta, Kazuyoshi, Utsunomiya, Fumiyasu, Tamachi, Tsuneaki, Iwasaki, Fumiharu, Sarata, Takafumi, Yanase, Norimasa
• Primary Examiner(s): Tso; Edward H
• Application Number:
  US10/812,437
• Publication Number:
  US 20040207361A1
• Time in Patent Office: 1,428 Days
• Field of Search: 320/103, 320/104, 320/134, 320/136, 320/140, 320/166
• US Class Current: 320/103
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

An electric equipment has a battery and an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery. A charge control circuit controls a charge current originating from the electric power of the battery and flowing from the battery to the electric condenser. The charge control circuit controls the charge current in accordance with a self-discharge rate of the battery. A load is driven with the electric power accumulated in the electric condenser.

Claims

1. An electric equipment comprising:

a battery;

an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery;

a charge control circuit that controls a charge current originating from the electric power of the battery and flowing from the battery to the electric condenser; and

a load driven with the electric power accumulated in the electric condenser;

wherein the charge control circuit controls the charge current in accordance with a self-discharge rate of the battery so that a battery voltage drop developed across the battery falls within a range of 5 to 20% of a battery voltage when the battery is in an open state.

2. An electric equipment comprising:

a battery;

an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery;

a charge control circuit that controls a charge current originating from the electric power of the battery and flowing from the battery to the electric condenser; and

a load driven with the electric power accumulated in the electric condenser;

wherein the charge control circuit controls the charge current in accordance with a self-discharge rate of the battery so that a battery voltage drop developed across the battery falls within a range of 10 to 40% of a battery voltage when the battery is in an open state.

3. An electric equipment comprising:

a battery;

an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery;

a charge control circuit that controls a charge current originating from the electric power of the battery and flowing from the battery to the electric condenser; and

a load driven with the electric power accumulated in the electric condenser;

wherein the load is driven in a first operation mode or a second operation mode consuming more current than in the first operation mode; and

wherein the charge control circuit charges the electric condenser in a first charge control mode with a charge current larger than a current consumed when the load is driven in the first operation mode and with a charge current smaller than a current consumed when the load is driven in the second operation mode.

4. An electric equipment according to claim 3;

wherein the charge control circuit controls the charge current so that a battery voltage drop developed across the battery falls within a range of 5 to 20% of the battery voltage when the battery is in an open state.

5. An electric equipment according to claim 3;

wherein a self-discharge rate of the battery is equal to or larger than 10%; and

wherein the charge control circuit controls the charge current so that a battery voltage drop developed across the battery falls within a range of 10 to 40% of the battery voltage when the battery is in an open state.

6. An electric equipment according to claim 3;

wherein the charge control circuit has a DC-DC converter for converting the electric power of the battery inputted into a conversion electric power having a different voltage; and

wherein a quantity of the conversion electric power of the DC-DC converter is controlled to control the charge current.

7. An electric equipment according to claim 3;

wherein the charge control circuit charges the electric condenser in a second charge control mode with a charge current equal to or larger than the current consumed when the load is driven in the second operation mode;

wherein when a quantity of accumulated electric power of the electric condenser exceeds a quantity of desired electric power, the electric condenser is charged in the first charge control mode; and

wherein when the quantity of accumulated electric power of the electric condenser is equal to or less than the quantity of desired electric power, the electric condenser is charged in the second charge control mode.

8. An electric equipment according to claim 7;

wherein a voltage of the electric condenser becomes equal to a predetermined voltage so that the quantity of accumulated electric power of the electric condenser becomes equal to the quantity of desired electric power.

9. An electric equipment according to claim 8;

wherein the charge control circuit has a DC-DC converter for converting the electric power of the battery into a conversion electric power having a different voltage; and

wherein a quantity of the conversion electric power of the DC-DC converter is controlled to control the charge current.

10. An electric equipment according to claim 9;

wherein the DC-DC converter includes a voltage control function of controlling the conversion electric power so that the voltage of the electric condenser becomes equal to the predetermined voltage; and

wherein the voltage control function operates in the second charge control mode.

11. An electric equipment according to claim 9;

wherein the DC-DC converter includes a first DC-DC converter for controlling the charge current so that a battery voltage drop developed across the battery becomes a predetermined amount, and a second DC-DC converter for controlling the charge current so that the voltage of the electric condenser becomes equal to the predetermined voltage; and

wherein in the first charge control mode, the electric condenser is charged using the first DC-DC converter, and in the second charge control mode, the electric condenser is charged using the second DC-DC converter.

12. An electric equipment comprising:

a battery;

an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery;

a charge control circuit that controls a charge current originating from the electric power of the battery and flowing from the battery to the electric condenser; and

a load driven with the electric power accumulated in the electric condenser;

wherein the charge control circuit controls the charge current in accordance with a self-discharge rate of the battery and has a first charge control mode that controls the charge current with a first charged electric power and a second charge control mode that controls the charge current with a second charged electric power greater than the first charged electric power; and

wherein the charge control circuit monitors a quantity of electric power accumulated by the electric condenser so that when the quantity of electric power accumulated by the electric condenser exceeds a preselected quantity, the charge control circuit controls the charge current to the electric condenser in the first charge control mode, and when the quantity of electric power accumulated by the electric condenser is less than or equal to the preselected quantity, the charge control circuit controls the charge current to the electric condenser in the second charge control mode.

13. An electric equipment comprising:

a battery;

an electric condenser that has an internal resistance lower than that of the battery and accumulates therein an electric power of the battery;

a charge control circuit that controls a charge current originating from the electric power of the battery and flowing to the electric condenser so that when a self-discharge of the battery is less than 10%, a battery voltage drop across the battery falls within a range of 5% to 20% of a battery voltage when the battery is in an open state, and so that when the self-discharge of the battery is equal to or larger than 10%, the battery voltage drop of the battery falls within a range of 10% to 40% of the battery voltage when the battery is in the open state; and

a load driven with the electric power accumulated in the electric condenser.

14. An electric equipment according to claim 13;

wherein the charge control circuit has a DC-DC converter for converting the electric power of the battery into a conversion electric power having a different voltage; and

wherein a quantity of the conversion electric power of the DC-DC converter is controlled to control the charge current.

15. An electric equipment according to claim 13;

wherein the battery comprises a fuel cell; and

wherein the electric condenser comprises a Ni-MR secondary battery or a lithium secondary battery.