Method and apparatus for battery charging with constant current, constant voltage, and pulsed charging

• US 7,098,627 B2
• Filed: 07/25/2003
• Issued: 08/29/2006
• Est. Priority Date: 07/30/2002
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nishida, Junji
• Primary Examiner(s): Easthom, Karl
• Assistant Examiner(s): PIGGUSH, AARON C
• Application Number:
  US10/626,732
• Publication Number:
  US 20040195996A1
• Time in Patent Office: 1,131 Days
• Field of Search: 320157-159, 320/155, 320137-139, 320110-114, 320/141, 320/148, 320/149, 320/152, 320/160, 320/162, 320/164, 324426-429, 324/433, 324/436
• US Class Current: 320/159
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A second battery charging apparatus includes a voltage detecting circuit, a current detecting circuit, a charging circuit, and a charge control circuit. The voltage detecting circuit detects a battery voltage of the second battery and accordingly outputs a signal. The current detecting circuit detects a battery current supplied to the second battery and accordingly outputs a signal. The charging circuit executes a current supply control to perform the charging to the second battery such that the battery voltage becomes equal to a voltage predetermined based on control signals and also that the charging current becomes equal to a current predetermined based on the control signals. The charge control circuit instructs the charging circuit with the control signals to set the battery voltage and the charge current in response to a voltage indicated by the signal from the voltage detecting circuit.

Claims

1. A battery charging apparatus which charges a battery, comprising:

a voltage detecting circuit arranged and configured to detect a battery voltage of said battery and for outputting a signal in response to a detected battery voltage;

a current detecting circuit arranged and configured to detect a charging current supplied to said battery and for outputting a signal in response to a detected charging current;

a charging circuit arranged and configured to control said charging current such that said detected battery voltage increases to become substantially equal to a first pre-set voltage in response to a first input control signal and also such that said detected charging current becomes substantially equal to a constant current predetermined in response to a second input control signal; and

a charge control circuit that instructs said charging circuit by said first and said second input control signals to set said first pre-set voltage and said constant current in response to said signal from said voltage detecting circuit,

wherein the charge control circuit is arranged and configured to instruct the charging circuit to perform constant current charging to flow a first constant current to the battery and subsequently to flow a second constant current greater than the first constant current to the battery when the detected battery voltage of the battery is smaller than a second pre-set voltage, and to instruct the charging circuit to perform pulse charging, in which flowing current to said battery and pausing current flow to said battery are alternately performed at intervals of a pre-determined time period,

wherein the charge control circuit instructs the charging circuit to control the charging current flowing to the battery such that a charging voltage applied across said battery becomes substantially equal to a third constant voltage during the constant current charging during the pulse charging and also such that the charging voltage becomes substantially equal to a first constant voltage smaller than the third constant voltage during the pausing in the pulse charging, and

wherein the charge control circuit instructs the charging circuit to control the charging current flowing through the battery such that the charging voltage becomes substantially equal to the first constant voltage when the battery voltage is smaller than the first pre-set voltage which is smaller than the second pre-set voltage and also such that the charging voltage becomes substantially equal to the second constant voltage which is less than the third constant voltage and greater than the first constant voltage, during the constant current charging before the pulse charging is executed.

3. The battery charging apparatus as defined in claim 1, wherein the charging circuit further comprises:

a constant voltage generating circuit that generates the first, second, and third constant voltages;

a voltage switching circuit that selects and outputs one of the first and third constant voltages output from the constant voltage generating circuit in accordance with the control signals from the charge control circuit;

a control transistor that outputs a current to the second battery in response to a control signal input thereto; and

a control circuit that controls the control transistor such that the battery voltage represented by a signal output from the voltage detecting circuit becomes substantially equal to a voltage represented by a signal output from the voltage switching circuit and that the charging current represented by a signal output from the current detecting circuit becomes substantially equal to a constant current represented by a signal received from a signal switching circuit.

5. The battery charging apparatus as defined in claim 3, wherein the current detecting circuit comprises:

a resistor through which the charging current to be supplied to the battery flows; and

a current detector that detects the charging current based on a voltage across the resistor and outputs a signal in response to the detected charging current,

wherein the voltage detecting circuit, the current detector of the current detecting circuit, the charge control circuit, a charge-end detecting circuit, and several components of the charging circuit including a constant voltage generating circuit, a voltage switching circuit, a constant current reference signal generating circuit, a signal switching circuit, and a control circuit are integrated into a single integrated circuit chip.

2. A battery charging apparatus which charges a battery, comprising:

a voltage detecting circuit arranged and configured to detect a battery voltage of said battery and for outputting a signal in response to a detected battery voltage;

a current detecting circuit arranged and configured to detect a charging current supplied to said battery and for outputting a signal in response to a detected charging current;

a charging circuit arranged and configured to control said charging current such that said detected battery voltage increases to become substantially equal to a first pre-set voltage in response to a first input control signal and also such that said detected charging current becomes substantially equal to a constant current predetermined in response to a second input control signal; and

a charge control circuit that instructs said charging circuit by said first and said second input control signals to set said first pre-set voltage and said constant current in response to said signal from said voltage detecting circuit.

wherein the charge control circuit is arranged and configured to instruct the charging circuit to perform constant current charging to flow a first constant current to the battery and subsequently to flow a second constant current greater than the first constant current to the battery when the detected battery voltage of the battery is smaller than a second pre-set voltage, and to instruct the charging circuit to perform pulse charging, in which flowing current to said battery and pausing current flow to said battery are alternately performed at intervals of a pre-determined time period.

wherein the charge control circuit instructs the charging circuit to control the charging current flowing to the battery such that a charging voltage applied across said battery becomes substantially equal to a third constant voltage during the constant current charging during the pulse charging and also such that the charging voltage becomes substantially equal to a first constant voltage smaller than the third constant voltage during the pausing in the pulse charging,

wherein the charge control circuit instructs the charging circuit to control the charging current flowing through the battery such that the charging voltage becomes substantially equal to the third constant voltage during the constant current charging before the pulse charging is executed, and

wherein the charging circuit further comprises;

a constant voltage generating circuit that generates said first, second, and third constant voltages;

a voltage switching circuit that selects and outputs one of the first and third constant voltages output from the constant voltage generating circuit in accordance with the control signals from the charge control circuit;

a control transistor that outputs a current to the battery in response to a control signal input to the control transistor; and

a control circuit that controls the control transistor such that the battery voltage represented by a signal output from the voltage detecting circuit becomes substantially equal to a voltage represented by a signal output from the voltage switching circuit and that the charging current represented by a signal output from the current detecting circuit becomes substantially equal to a constant current represented by a signal output from the a signal switching circuit arranged and configured to supply signals to said control circuit.

4. The battery charging apparatus as defined in claim 2, wherein the current detecting circuit comprises:

a resistor through which the charging current to be supplied to the battery flows; and

a current detector that detects the charging current based on a voltage across the resistor and outputs a signal in response to the detected charging current,

wherein the voltage detecting circuit, the current detector of the current detecting circuit, the charge control circuit, a charge-end detecting circuit, and several components of the charging circuit including a constant voltage generating circuit, a voltage switching circuit, a constant current reference signal generating circuit, a signal switching circuit, and a control circuit are integrated into a single integrated circuit chip.

6. A charging method for a battery, comprising the steps of:

first performing a first constant current charging by supplying a first constant current to the battery when a battery voltage of the battery is smaller than a first pre-set voltage;

second performing a second constant current charging by supplying a second constant current greater than the first constant current to the battery when the battery voltage of the battery is greater than the first pre-set voltage; and

operating a pulse charging of the battery when the battery voltage of the battery increases to be equal to or greater than a second pre-set voltage greater than the first pre-set voltage by alternately carrying out, at intervals of a predetermined time period, a constant current charging in which the second constant current is supplied to the battery and a pausing in which the supply of the constant current charging is stopped,

wherein the operating step comprises controlling a charging current to the battery such that a charging voltage of the battery becomes substantially equal to a third constant voltage during the constant current charging of the pulse charging and such that the charging voltage of the battery becomes substantially equal to a first constant voltage smaller than the third constant voltage during the pausing of the pulse charging, and

wherein the charging current to the battery is controlled such that the charging voltage of the battery becomes substantially equal to the first constant voltage when the battery voltage of the battery is smaller than the first pre-set voltage during the first constant current charging and such that the charging voltage of the battery becomes substantially equal to a second constant voltage smaller than the third constant voltage and greater than the first constant voltage during the first constant current charging.

7. A battery charging apparatus which charges a battery, comprising:

a voltage detecting circuit arranged and configured to detect a battery voltage of said battery and for outputting a signal in response to a detected battery voltage;

a current detecting circuit arranged and configured to detect a charging current supplied to said battery and for outputting a signal in response to a detected charging current;

a charging circuit arranged and configured to control said charging current such that said detected battery voltage increases to become substantially equal to a first pre-set voltage in response to an input control signal and also such that said detected charging current becomes substantially equal to a constant current predetermined in response to the input control signal; and

a charge control circuit that instructs said charging circuit by the input control signal to set said first pre-set voltage and said constant current in response to said signal from said voltage detecting circuit,

wherein the charge control circuit is arranged and configured to instruct the charging circuit to perform constant current charging to flow a first constant current to the battery and subsequently to flow a second constant current greater than the first constant current to the battery when the detected battery voltage of the battery is smaller than a second pre-set voltage, and to instruct the charging circuit to perform pulse charging, in which flowing current to said battery and pausing current flow to said battery are alternately performed at intervals of a pre-determined time period,

wherein the charge control circuit instructs the charging circuit to control the charging current flowing to the battery such that a charging voltage applied across said battery becomes substantially equal to a third constant voltage during the constant current charging during the pulse charging and also such that the charging voltage becomes substantially equal to a first constant voltage smaller than the third constant voltage during the pausing in the pulse charging, and

wherein the charge control circuit instructs the charging circuit to control the charging current flowing through the battery such that the charging voltage becomes substantially equal to the first constant voltage when the battery voltage is smaller than the first pre-set voltage which is smaller than the second pre-set voltage and also such that the charging voltage becomes substantially equal to the second constant voltage which is less than the third constant voltage and greater than the first constant voltage, during the constant current charging before the pulse charging is executed.

9. The battery charging apparatus as defined in claim 7, wherein the charging circuit further comprises:

a constant voltage generating circuit that generates the first, and third constant voltages;

a voltage switching circuit that selects and outputs one of the first and third constant voltages output from the constant voltage generating circuit in accordance with the control signals from the charge control circuit;

a control transistor that outputs a current to the battery in response to a control signal input thereto; and

a control circuit that controls the control transistor such that the battery voltage represented by a signal output from the voltage detecting circuit becomes substantially equal to a voltage represented by a signal output from the voltage switching circuit and that the charging current represented by a signal output from the current detecting circuit becomes substantially equal to a constant current represented by a signal received from a signal switching circuit.

10. The battery charging apparatus as defined in claim 7, wherein the current detecting circuit comprises:

a resistor through which the charging current to be supplied to the battery flows; and

a current detector that detects the charging current based on a voltage across the resistor and outputs a signal in response to the detected charging current,

wherein the voltage detecting circuit, the current detector of the current detecting circuit, the charge control circuit, a charge-end detecting circuit, and several components of the charging circuit including a constant voltage generating circuit, a voltage switching circuit, a constant current reference signal generating circuit, a signal switching circuit, and a control circuit are integrated into a single integrated circuit chip.

11. The battery charging apparatus as defined in claim 9, wherein the current detecting circuit comprises:

a resistor through which the charging current to be supplied to the battery flows; and

a current detector that detects the charging current based on a voltage across the resistor and outputs a signal in response to the detected charging current,

wherein the voltage detecting circuit, the current detector of the current detecting circuit, the charge control circuit, a charge-end detecting circuit, and several components of the charging circuit including a constant voltage generating circuit, a voltage switching circuit, a constant current reference signal generating circuit, a signal switching circuit, and a control circuit are integrated into a single integrated circuit chip.

8. A battery charging apparatus which charges a battery, comprising:

a voltage detecting circuit arranged and configured to detect a battery voltage of said battery and for outputting a signal in response to a detected battery voltage;

a current detecting circuit arranged and configured to detect a charging current supplied to said battery and for outputting a signal in response to a detected charging current;

a charging circuit arranged and configured to control said charging current such that said detected battery voltage increases to become substantially equal to a first pre-set voltage in response to an input control signal and also such that said detected charging current becomes substantially equal to a constant current predetermined in response to the input control signal;

a charge control circuit that instructs said charging circuit by the input control signal to set said first pre-set voltage and said constant current in response to said signal from said voltage detecting circuit;

a constant voltage generating circuit that generates said first, and third constant voltages;

a voltage switching circuit that selects and outputs one of the first and third constant voltages output from the constant voltage generating circuit in accordance with the control signals from the charge control circuit;

a control transistor that outputs a current to the battery in response to a control signal input to the control transistor; and

a control circuit that controls the control transistor such that the battery voltage represented by a signal output from the voltage detecting circuit becomes substantially equal to a voltage represented by a signal output from the voltage switching circuit and that the charging current represented by a signal output from the current detecting circuit becomes substantially equal to a constant current represented by a signal output from a signal switching circuit arranged and configured to supply signals to said control circuit,

wherein the charge control circuit is arranged and configured to instruct the charging circuit to perform constant current charging to flow a first constant current to the battery and subsequently to flow a second constant current greater than the first constant current to Like battery when the detected battery voltage of the battery is smaller than a second pre-set voltage, and to instruct the charging circuit to perform pulse charging, in which flowing current to said battery and pausing current flow to said battery are alternately performed at intervals of a pre-determined time period,

wherein the charge control circuit instructs the charging circuit to control the charging current flowing to the battery such that a charging voltage applied across said battery becomes substantially equal to a third constant voltage during the constant current charging during the pulse charging and also such that the charging voltage becomes substantially equal to a first constant voltage smaller than the third constant voltage during the pausing in the pulse charging, and

wherein the charge control circuit instructs the charging circuit to control the charging current flowing through the battery such that the charging voltage becomes substantially equal to the third constant voltage during the constant current charging before the pulse charging is executed.