Method and apparatus for maximizing the sustainable flash of a handheld portable electronic device
First Claim
1. A method for maintaining a maximum sustainable flash current over the duration of a flash using a programmable current drive in a handheld electronic portable device powered by a battery of a given type, the handheld electronic portable device placing variable loads on the battery in addition to the flash, comprising:
- initiating a flash command;
prior to initiating the flash in response to the flash command;
measuring the voltage across the battery (Vb1) under normal system load;
recording any high current load occurring during the measurement of Vb1;
initiating the flash at an initial flash current;
calculating a maximum current that can be drawn from the battery without adversely affecting operation of the handheld electronic portable device by;
measuring the voltage across the battery with flash (Vb2) after a predetermined period;
recording any high current load occurring during the measurement of Vb2;
calculating an equivalent series resistance (ESR) of the battery at the end of the predetermined period factoring in any high current loads determined to have occurred during measurement of Vb1 and Vb2;
determining an ESR value for a predetermined flash current pulse duration based on the ESR of the battery at the end of the predetermined period;
calculating the maximum current based on the ESR value and potential high current loads due to the variable loads; and
adjusting the flash current to approximate the calculated maximum current to maintain the maximum sustainable flash current over the duration of the flash current pulse.
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Accused Products
Abstract
A method and apparatus for maintaining a maximum sustained flash current over the whole length of a flash using a programmable current drive in a handheld portable device powered by a battery. The method involves measuring the battery voltage before and after a flash is initiated and calculating the equivalent series resistance (ESR) of the battery. The calculated ESR is then used to adjust the flash current. The process may be repeated to correct for errors in the flash current.
9 Citations
20 Claims
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1. A method for maintaining a maximum sustainable flash current over the duration of a flash using a programmable current drive in a handheld electronic portable device powered by a battery of a given type, the handheld electronic portable device placing variable loads on the battery in addition to the flash, comprising:
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initiating a flash command; prior to initiating the flash in response to the flash command; measuring the voltage across the battery (Vb1) under normal system load; recording any high current load occurring during the measurement of Vb1; initiating the flash at an initial flash current; calculating a maximum current that can be drawn from the battery without adversely affecting operation of the handheld electronic portable device by; measuring the voltage across the battery with flash (Vb2) after a predetermined period; recording any high current load occurring during the measurement of Vb2; calculating an equivalent series resistance (ESR) of the battery at the end of the predetermined period factoring in any high current loads determined to have occurred during measurement of Vb1 and Vb2; determining an ESR value for a predetermined flash current pulse duration based on the ESR of the battery at the end of the predetermined period; calculating the maximum current based on the ESR value and potential high current loads due to the variable loads; and adjusting the flash current to approximate the calculated maximum current to maintain the maximum sustainable flash current over the duration of the flash current pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A handheld portable electronic device powered by a battery of a given type comprising:
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a flash device; a programmable current drive for initiating the flash device at an initial flash current; at least one voltage measuring device for measuring, prior to initiating the flash, the voltage across the battery (Vb1) under normal system load, and for measuring the voltage across the battery with flash (Vb2) a predetermined period after the flash device is initiated; at least one recording device for recording any high current load occurring during the measurement of Vb1 and for recording any high current load occurring during the measurement of Vb2; a microprocessor configured to calculate a maximum current that can be drawn from the battery without adversely affecting operation of the handheld portable electronic device by; calculating an equivalent series resistance (ESR) of the battery at the end of the predetermined period factoring in any high current loads determined to have occurred during measurement of Vb1 and Vb2, determining an ESR value for a predetermined flash current pulse duration based on the ESR of the battery at the end of the predetermined period, and calculating the maximum current based on the ESR value and potential high current loads due to variable operating loads on the device, and cause the programmable current drive to adjust the flash current to approximate the calculated maximum current to maintain the maximum sustainable flash current over the duration of the flash current pulse. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification