Battery capacity detection apparatus and detection method

• US 7,235,949 B2
• Filed: 06/21/2004
• Issued: 06/26/2007
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Ikeda, Makoto
• Primary Examiner(s): Easthom; Karl
• Assistant Examiner(s): Berhanu; Samuel
• Application Number:
  US10/873,030
• Publication Number:
  US 20050024018A1
• Time in Patent Office: 1,100 Days
• Field of Search: 320/132, 320/127, 320/134
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm

Abstract

A detection device and method for accurately detecting the battery capacity remaining in the device independent of the operating mode of the device. When the battery-powered device is operating in a low load mode, the battery discharge voltage is A/D converted and the remaining battery capacity is determined based on the resulting digital signal. When the battery-powered device is operating in a high load mode, the battery discharge voltage is compared with specific threshold voltages, and an interrupt process is run based on the comparison result to calculate the remaining battery capacity.

Claims

1. A battery capacity detection apparatus for detecting the remaining capacity in a battery installed in a device capable of operating in either a high load mode or a low load mode, comprising:

a microprocessor for determining if the device is in the low load mode or in the high load mode of operation;

an operating mode detection circuit for detecting the analog discharge voltage of the battery;

an A/D converter for converting the detected analog discharge voltage of said battery into a digital output signal; and

a comparator for comparing the detected analog discharge voltage of said battery with a specific reference voltage;

wherein when said microprocessor determines that the operating mode of the device is the low load mode said microprocessor calculates the battery capacity remaining in said battery directly from said digital output signal from the A/D converter and wherein when said microprocessor determines that the operating mode of the device is in the high load mode said microprocessor calculates the battery capacity remaining in said battery from an output of said comparator based upon an interrupt process of the microprocessor.

2. A battery capacity detection apparatus as described in claim 1, further comprising a thermistor for measuring battery temperature and for providing a thermistor output corresponding to the measured temperature, with said microprocessor calculation of the remaining battery capacity dependent upon said thermistor output.

3. A battery capacity detection apparatus as described in claim 1 wherein said microprocessor determines the operating mode of the device based on the on/off status of a predetermined mechanical or thermal operating part of the device.

4. A battery capacity detection apparatus as described in claim 2 wherein said microprocessor determines the operating mode of the device based on the on/off status of a predetermined mechanical or thermal operating part of the device.

5. A battery capacity detection apparatus as described in claim 1 wherein the comparator is a parallel arrangement of multiple comparators with each comparator providing a given output signal when the comparison voltage from such comparator is lower than a given threshold voltage corresponding to different levels of remaining capacity in said battery during the high load mode of operation.

6. A battery capacity detection apparatus for detecting remaining capacity in a battery installed in a device capable of operating in either a high load mode or a low load mode, comprising:

circuit means for determining if the device is operating in a low load mode or a high load mode;

an A/D converter for converting the analog discharge voltage of the battery to a digital value;

a comparator for comparing the battery analog discharge voltage with a specific threshold reference; and

wherein when said circuit means determines that the operating mode of the device is the low load mode, the circuit means calculates remaining battery capacity according to a program directly from the digital output value from the A/D converter and calculating the remaining battery capacity from an output of the comparator when the circuit means determines that the operating mode of the device is in the high load mode based upon an interrupt process.

7. A battery capacity detection method for detecting remaining capacity in a battery installed in a device capable of operating in either a high load mode or a low load mode, comprising steps of:

determining if the device is operating in the low load mode or in the high load mode;

converting the analog discharge voltage of the battery into a digital output signal;

comparing the battery analog discharge voltage with a specific threshold reference to generate a comparator output and

using a microprocessor for calculating the capacity remaining in the battery directly from the digital output signal only when the device is operating in the low load mode; and

for calculating the capacity remaining in the battery from said comparator output based upon an interrupt process of the microprocessor only when the device is operating in the high load mode.

8. A battery capacity detection method as described in claim 7, wherein battery temperature is measured and the measured temperature is referenced by said microprocessor to calculate remaining battery capacity.

9. A battery capacity detection method for detecting remaining capacity in a battery installed in a device, comprising:

an operating mode detection step for determining if the device is operating in a low load mode or a high load mode;

an A/D conversion step for converting an analog battery output to a digital value;

a comparison step for comparing battery output with a specific reference output; and

a calculation step for calculating remaining battery capacity directly from the digital output from the A/D conversion step when the operating mode detection step determines the device is operating in the low load mode, and for calculating remaining battery capacity based on the comparison step using a microprocessor to perform the calculation step when the operating mode detection step determines the device is operating in the high load mode.