Extended life smoke detector
First Claim
1. A smoke detector of the type powered by a battery, said smoke detector having means for triggering an alarm in response to a concentration of smoke above a threshold value, said smoke detector having means for triggering an alarm when the battery voltage falls below a threshold voltage, said battery having a service life within said smoke detector of at least one year, wherein the improvement comprises:
- a) a lithium anode primary battery powering said smoke detector; and
b) means for providing a periodic pulse current to said battery, the magnitude of said pulse current falling within the range of zero to about 11 mA.
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Accused Products
Abstract
The present invention is an improvement in battery powered smoke detectors. A smoke detector is powered by a series connection of two Li/SOCl2 cells having a capacity of about 2 amp hours. The smoke detector draws a quiescent current of about 7 μA. A low voltage alarm activates when the battery voltage falls below about 6.0 volts upon the periodic application of about a 250 μA to about a 1 mA battery test pulse. The cells are soldered directly into the smoke detector PC board and the smoke detector is placed in an unopenable case to deter battery removal. Smoke detector life expectancy including the battery is 15 years.
This invention was made with Government support under grant number SOH (AHR-B) 1 R43 CE00014-01 awarded by the Centers for Disease Control (CDC), Center for Environmental Health and Injury Control (CEHIC), Division of Injury Control. The Government has certain rights in this invention.
24 Citations
10 Claims
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1. A smoke detector of the type powered by a battery, said smoke detector having means for triggering an alarm in response to a concentration of smoke above a threshold value, said smoke detector having means for triggering an alarm when the battery voltage falls below a threshold voltage, said battery having a service life within said smoke detector of at least one year, wherein the improvement comprises:
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a) a lithium anode primary battery powering said smoke detector; and b) means for providing a periodic pulse current to said battery, the magnitude of said pulse current falling within the range of zero to about 11 mA. - View Dependent Claims (2, 3, 4, 5)
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6. A smoke detector comprising:
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(a) an electronic circuit, said electronic circuit having means for triggering an alarm in response to a concentration of smoke above a threshold value, said electronic circuit having means for triggering an alarm in response to its supply voltage falling below a threshold voltage, said threshold voltage having a range of about 7.0 volts to about 5.6 volts; and (b) a battery, said battery providing said supply voltage to said electronic circuit, said battery comprising a series connection of two Li/SOCl2 primary cells, said battery having a capacity of about 2 amp hours; and (c) means for providing a periodic pulse current to said battery, the magnitude of said pulse current falling within the range of zero to about 5 mA. - View Dependent Claims (7, 8, 9, 10)
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Specification